A retrospective analysis of clinical characteristics and prognostic factors for 152 cases of Staphylococcus aureus bloodstream infection / 中华预防医学杂志

To understand the clinical characteristics of Staphylococcus aureus bloodstream infection and the main risk factors affecting clinical prognosis, providing a reference for clinical prevention and control of Staphylococcus aureus bloodstream infection. In this study, the clinical data of 152 patients with Staphylococcus aureus bloodstream infection admitted to Guangdong Provincial People's Hospital from January 2019 to December 2021 were retrospectively analyzed by reviewing the electronic medical record system, including underlying diseases, clinical characteristics, risk factors, and bacterial resistance. Statistical methods such as Chi-Squared Test and t Test were used to analyze the related risk factors that may affect the clinical characteristics and prognosis of patients with Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection, then the variables with P<0.05 in univariate analysis were included in the multivariate logistic regression model to analyze the independent risk factors of poor prognosis. The results showed among 152 patients with Staphylococcus aureus bloodstream infection, 50 patients (32.89%) were infected with MRSA. In comparison, 102 patients (67.11%) were infected with methicillin-sensitive Staphylococcus aureus (MSSA). Except for rifampicin, the resistance rate of MRSA to commonly used antibiotics was all higher than that of MSSA, and the difference was statistically significant (Chi-square values were 8.272, 11.972, 4.998, 4.776, respectively;all P-values are less than 0.05). Strains resistant to vancomycin, linezolid, and quinupristin/dalfopristin were not found. In the MRSA group, indwelling catheter and drainage tube, carbapenems, and β-lactamase inhibitor treatment were significantly higher than the MSSA group. The difference was statistically significant (P<0.05). The incidence of poor prognosis of bloodstream infection in the MRSA group was higher than that in the MSSA group (34.00% vs 13.73%), and the difference was statistically significant (χ2=8.495, P<0.05). No independent risk factors associated with poor prognosis were found in the included patients with MRSA bloodstream infection.Multivariate Logistic regression model analysis showed that solid malignant tumors (OR=13.576, 95%CI: 3.352-54.977, P<0.05), mechanical ventilation (OR=7.468, 95%CI: 1.398-39.884, P<0.05) were the most important independent risk factors for poor prognosis in patients with Staphylococcus aureus bloodstream infection. In summary, the poor prognosis rate of MRSA bloodstream infection is higher than that of MSSA. The clinical evaluation of related risk factors should be strengthened, targeted prevention and control interventions should be taken to improve the prognosis of patients with Staphylococcus aureus bloodstream infection, and the use of antibiotics should be rational and standardized, to control bacterial infection and drug resistance effectively .

Prevalencia de portación nasal de Staphylococcus aureus sensible y resistente a la meticilina en candidatos a artroplastia total de cadera o rodilla / Prevalence of nasal carriage of methicillin-sensitive and methicillin-resistant Staphylococcus aureus in candidates for total hip or knee arthroplasty

INTRODUCIÓN Las infecciones perioperatorias en cirugía de reemplazo articular son fuente importante de morbimortalidad, así como de altos costos económicos y sociales, tanto para el paciente como para su entorno. La colonización preoperatoria por Staphylococcus aureus ha sido reconocida como un factor de riesgo importante para desarrollar una infección de sitio quirúrgico.El objetivo de este estudio es conocer la prevalencia de portación nasal de S. aureus, tanto sensible a la meticilina (SASM) como resistente a la meticilina (SARM), en pacientes candidatos a cirugía de reemplazo articular de cadera o rodilla. MATERIALES Y MÉTODOS Se realizó un estudio observacional de una cohorte retrospectiva de pacientes con indicación de artroplastia total de cadera (ATC) y rodilla (ATR) electiva por artrosis severa en un hospital público de Chile. Los pacientes fueron sometidos a tamizaje preoperatorio de portación, cultivándose muestras obtenidas mediante hisopado de ambas fosas nasales. Los datos del laboratorio fueron recopilados y presentados como porcentaje de portación de S. aureus. RESULTADOS Se estudiaron 303 pacientes consecutivos de ATC y 343 de ATR. En total, 483 de los 646 pacientes (74,7%) tuvieron estudio preoperatorio de portación nasal. Se identificaron 123 pacientes (25,4%) portadores de S. aureus, de los cuales sólo 2 (0,41%) casos correspondieron a SARM. CONCLUSIÓN La prevalencia de portación nasal de S. aureus obtenida fue de 25%, similar a lo reportado en otras series. La prevalencia de SARM (0.41%), sin embargo, estuvo bajo lo descrito en la literatura internacional (0,6­6%). Sería de utilidad, dada la alta prevalencia de portación descrita en nuestro trabajo y de acuerdo a evidencia publicada recientemente, realizar protocolos de descolonización universales, sin necesidad de realizar tamizaje preoperatorio.

INTRODUCTION Surgical-site infections in joint replacement surgery are an important source of morbidity and mortality that entail high economic and social burden both for the patient and their environment. Preoperative colonization by Staphylococcus aureus has been recognized as an important risk factor for the development of surgical-site infection. The aim of the present study is to determine the prevalence of nasal colonization by S. aureus, both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) in patients who are candidates for total replacement of the hip or knee joints. MATERIALS AND METHODS A retrospective observational study of a cohort of 646 patients with an indication to undergo total hip arthroplasty (THA) or total knee arthroplasty (TKA) due to severe osteoarthritis was performed in a Public Hospital in Chile. The patients were submitted to a preoperative screening for S. aureus carriage, and the culture samples were obtained by swabbing both nostrils. The laboratory data was collected and presented as a percentage of carriage. RESULTS We consecutively examined 303 THA and 343 TKA patients. A total of 483 of the 646 patients (74.7%) underwent a preoperative study of nasal carriage. We identified 123 (25.4%) S. aureus carriers, and only found 2 (0.41%) cases corresponding to MRSA. CONCLUSION We found a prevalence of nasal carriage of S. aureus of 25.4%, a rate similar to that reported in other series. The prevalence of MRSA (0.41%), however, was lower than that reported in the international literature (0.6­6%). Given the high prevalence of carriage described in our work and according to recently published data, it would be worthwhile to carry out universal decolonization protocols, without the need for preoperative screening.

Portación nasal, antibiotipo y genotipo de cepas de Staphylococcus aureus aisladas en estudiantes de Medicina y de Enfermería Campus San Felipe, Universidad de Valparaíso, Chile, durante el año 2017 / Nasal carriage, antibiotype and genotype of isolated Staphylococcus aureus from Medicine and Nursing students of Campus San Felipe, University of Valparaiso, Chile, during 2017

INTRODUCCIÓN. Staphylococcus aureus es parte de la microbiota nasal en 20-30% de la población general, colonización que constituye un reservorio para su transmisión, lo que es preocupante en cepas resistentes a meticilina (SARM). OBJETIVO: Determinar la prevalencia de S. aureus en estudiantes de Medicina y Enfermería del Campus San Felipe y caracterizar sus aislamientos. MATERIAL Y MÉTODOS: El 2017 se midió la portación nasal a 225 estudiantes, a las cepas aisladas se le analizó su antibiotipo por difusión en agar, la relación clonal por electroforesis de campo pulsado y MLST. En SARM se determinó el cassette SCCmec y gen de la leucocidina de Panton-Valentine. RESULTADOS: 61 estudiantes portaron S. aureus (27,1%) incluyendo dos cepas SARM (0,9%). Staphylococcus aureus mostró resistencia a penicilina (75%), eritromicina (14%) y clindamicina (10%), cloranfenicol (1,6%) y levofloxacina, oxacilina, cefoxitina (3,3%). Se diferenciaron diecinueve pulsotipos y el secuenciotipo coincidió con complejos clonales descritos a nivel mundial en portadores de S. aureus: CC30, CC8, CC97, CC15, CC22 y CC1. Las dos cepas SARM correspondieron con los clones chileno/cordobés y USA100NY/J, ambas del CC5. CONCLUSIÓN: La portación nasal de S. aureus y SARM en los estudiantes coincidió con la portación en la población general y las cepas sensibles a meticilina mostraron diversidad clonal y alta susceptibilidad antimicrobiana, exceptuando a penicilina.

BACKGROUND: Staphylococcus aureus is part of the nasal microbiota in 20-30% of the population. This colonization is also a reservoir for its dissemination, which is worrying in the case of strains with resistance to methicillin (MRSA). AIM: To determine S. aureus nasal carriage in nursing and medical students of San Felipe Campus and characterize theirs isolates. METHODS: During 2017, nasal swabs were taken from 225 students and seeded in salt manitol agar. Antibiotypes were determined by agar diffusion and the genetic clonality was assessed by PFGE and MLST in isolated S. aureus. SCCmec cassette and Panton-Valentine leukocidin gene (pvl) presence were determined in the MRSA isolates. RESULTS: 61 students carried S. aureus (27.1%) including two MRSA strains (0.9%). S. aureus showed resistance to penicillin (75%), erythromycin (14%) and clindamycin (10%), chloramphenicol (1.6%) and levofloxacin, oxacillin, cefoxitin (3.3%). Nineteen PFGE-types were differentiated, and their sequence-types coincided with main clonal complexes described in S. aureus carriers from different places worldwide: CC30, CC8, CC97, CC15, CC22 and CC1. MRSA strains belonged to CC5 and they corresponded to the Chilean/Cordobes and USA100NY/J clones. CONCLUSION: Nasal carriage of S. aureus and MRSA in students, coincided with the general population and sensitive-methicillin strains showed clonal diversity and high antimicrobial susceptibility except for penicillin.

Piomiositis, artritis séptica y osteomielitis aguda porStaphylococcus aureus meticilino resistente de la comunidad enpaciente pediátrico / Pyomyositis, septic arthritis and acute osteomyelitis due tocommunity methicillin-resistant Staphylococcus aureus in apediatric patient

Las infecciones osteoarticulares y musculoesqueléticas son patologías infecciosas relativamente infrecuentes en la infancia, afectando generalmente a varones y menores de 5 años. Países desarrollados reportan una incidencia anual de osteomielitis de 10 a 80/100.000 niños y de 4 casos/100.000 niños para artritis séptica. En países tropicales, la piomiositis tiene una incidencia de un caso por cada 2.000 habitantes. El Staphylococcus aureus es el principal agente causal. En la infancia la vía más común del legada del germen a la articulación es la hematógena. Hasta en un 30% de niños coexisten osteomielitis aguda y artritis séptica. Se presenta el caso de preescolar masculino de 3años, quien posterior a aplastamiento de miembro inferior izquierdo, presenta aumento de volumen, dolor y limitación para la marcha, asociándose 9 días después fiebre de 39.5°C,acudiendo al Hospital Universitario de Caracas. La anamnesis, evaluación clínica y estudios paraclínicos fueron sugestivos depiomiositis de muslo izquierdo, osteomielitis de fémur izquierdo y artritis séptica de rodilla izquierda. Se indica antibioticoterapiacon cobertura para Staphylococcus aureus (ciprofloxacina y clindamicina). Se realizó artrotomía evacuadora y limpieza quirúrgica de estructuras afectadas. El cultivo reportó Staphylococcus aureus sensible a ciprofloxacina, gentamicina, linezolid, rifampicina, trimetropin/sulfametoxazol; resistentea clindamicina, eritromicina, oxacilina, por lo que se omitióclindamicina y se indicó trimetropin/sulfametoxazol. Cumplió21 días de tratamiento intravenoso, observándose evolución satisfactoria por lo que se decidió egreso, dando continuidad con tratamiento vía oral por cuatro semanas y seguimiento interdisciplinario. El abordaje oportuno y adecuado de estas patologías disminuye el riesgo de desarrollar complicaciones(AU)

Osteoarticular and musculoskeletal infections are relatively rare infectious diseases in childhood, generally affecting men and children under 5 years of age. Developed countries report an annual incidence of osteomyelitis of 10 to 80 / 100,000 children and 4 cases / 100,000 children for septicarthritis. In tropical countries, pyomyositis has an incidence of one case for every 2,000 inhabitants. Staphylococcus aureusis the main causative agent. In childhood the most commonroute of arrival of the germ to the joint is hematogenous.Up to 30% of children coexist acute osteomyelitis and septic arthritis. We present the case of a 3-year-old male preschoolerwho, after crushing his left lower limb, presented an increasein volume, pain, and limited gait, and was associated witha fever of 39.5 ° C 9 days later, going to the University Hospital of Caracas. the anamnesis, clinical evaluation and paraclinical studies were suggestive of pyomyositis of the leftthigh, osteomyelitis of the left femur and septic arthritis of the left knee. Antibiotic therapy with coverage for Staphylococcus aureus (ciprofloxacin and clindamycin) is indicated. Evacuating arthrotomy and surgical cleaning of affected structures were performed. The culture reported Staphylococcus aureus sensitiveto ciprofloxacin, gentamicin, linezolid, rifampin, trimetropin /sulfamethoxazole; resistant to clindamycin, erythromycin,oxacillin, therefore clindamycin was omitted and trimetropin /sulfamethoxazole was indicated. He completed 21 days ofintravenous treatment, observing satisfactory evolution so hisdis charge was decided, continuing with oral treatment for four weeks and interdisciplinary follow-up. The timely and adequate approach to these pathologies reduces the risk of developing complications(AU)

Staphylococcus aureus sensible a meticilina, productor de leucocidina de Panton Valentine: a propósito de dos casos pediátricos de infección osteoarticular / Panton-Valentine leukocidin toxin associated methicillin-susceptible Staphylococcus aureus infection: a report of two pediatric cases

Resumen Staphylococcus aureus coloniza la nasofaringe en un tercio de los individuos sanos y además es causante de infecciones graves en pediatría, como endocarditis, neumonía e infecciones osteoarticulares. Posee varios mecanismos de virulencia, siendo la leucocidina de Panton Valentine (LPV) uno de ellos, una exotoxina que causa muerte celular. Su producción está comúnmente relacionada con Staphylococcus aureus resistente a meticilina (SARM) e infecciones pulmonares y musculo-esqueléticas graves. Sin embargo, la producción de LPV no es exclusiva de SARM. Se presentan dos casos clínicos de pacientes con infección por Staphylococcus aureus sensible a meticilina productora de esta exotoxina.

Abstract Staphylococcus aureus colonizes the nasopharynx in one third of healthy individuals and is also responsible for several infections in pediatrics such as endocarditis, pneumonia and osteoarticular infections. It has several virulence mechanisms, such as Panton Valentine leukocidin (PVL), which is an exotoxin that causes cell death. It is commonly related to methicillin-resistant Staphylococcus aureus (MRSA) and more serious pulmonary and musculoskeletal infections. However, PVL is not exclusive to MRSA. Two clinical cases of patients with infection by methicillin-sensitive Staphylococcus aureus producing this exotoxin are presented.

Sodium fluoroacetate poisoning: A case report / Intoxicación por fluoroacetato de sodio, un reporte de caso

Abstract Introduction: Sodium fluoroacetate, known as compound 1080, was discovered in Germany during the Second World War. It is usually used as a rodenticide, it is an odorless and tasteless substance, with a lethal dose in humans of 2 mg / kg that is why it was withdrawn from the market in some countries, including Colombia; however, it is obtained illegally. This substance has biochemical and physiological effects at the cellular level that alter the transport of citrate at the mitochondrial level, generating accumulation of lactic acid and alteration of the glucose use. The clinical manifestations are nonspecific since there is no any cardinal symptom. Therefore, its diagnosis is made due to high clinical suspicion associated with establishment of exposure to the compound in view of the difficulty to obtain paraclinical confirmation in a timely manner. Methods: We present a case report of intentional ingestion of sodium fluoroacetate in an adolescent that is associated with an infection added to the bloodstream by methicillin- sensitive Staphylococcus aureus (MSSA). The patient developed multiple complications that lead to support in the Intensive Care Unit (ICU) with a satisfactory outcome. In view of the lack of a specific antidote, she was treated with ethanol in order to increase the level of acetate; thus, offering an alternative substrate to the Krebs cycle. It is suggested that the ethanol offers benefits in the acute treatment of these patients. Results: The patient with sodium fluoroacetate poisoning and kidney failure received renal replacement therapy with a favorable evolution and survival at discharge from the intensive care unit of a third-level hospital in the city of Pereira, Risaralda, Colombia. Conclusions: Sodium fluoroacetate poisoning is relatively rare and can cause acute kidney injury and multi-organ failure with a high rate of complications and death. A case of self-inflicted poisoning that received a timely manner continuous renal replacement therapy with a favorable outcome in terms of ICU survival was presented.

Resumen Introducción: El fluoroacetato de sodio ⎯conocido como compuesto 1080⎯, fue descubierto en Alemania durante la segunda guerra mundial, suele ser utilizado como raticida y se caracteriza por ser una sustancia inodora e insabora. En humanos, una dosis de 2 a mg/kg es letal; debido a su toxicidad fue retirado del mercado en algunos países, incluyendo Colombia, no obstante, se consigue de forma ilegal. Esta sustancia tiene efectos bioquímicos y fisiológicos a nivel celular que altera el transporte del citrato a nivel mitocondrial, generando acumulación de ácido láctico y alteración en la utilización de la glucosa. Las manifestaciones clínicas son inespecíficas y no existe un síntoma cardinal. Por ende, su diagnóstico se realiza por alta sospecha clínica, asociado al establecimiento de la exposición al compuesto, ya que la confirmación paraclínica es difícil de realizar oportunamente. Métodos: Se presenta un reporte de caso de ingestión intencional en un adolescente, asociado con infección agregada al torrente sanguíneo por Estafilococos Aureos Meticilino Sensible (EAMS). El paciente desarrolló múltiples complicaciones y requirió asistencia en Unidad de Cuidados Intensivos (UCI) con desenlace satisfactorio. Ya que no se cuenta con antídoto específico , se le dio tratamiento con etanol para aumentar el nivel de acetato, ofreciendo así un sustrato alterno al ciclo de Krebm. Se estima que el etanol puede ofrecer beneficios en el tratamiento agudo de estos pacientes. Resultados: Paciente con intoxicación por fluoroacetato de sodio e insuficiencia renal, recibe terapia de reemplazo renal con un evolución favorable y supervivencia al alta de la Unidad de Cuidados Intensivos de un hospital de tercer nivel en la ciudad de Pereira, Risaralda, Colombia. Conclusiones: La intoxicación por fluoroacetato de sodio es relativamente poco frecuente y puede causar injuria renal aguda y falla multiorgánica con alta tasa de complicaciones y muerte. Se presentó un caso de intoxicación autoinfligida que recibió terapia de reemplazo renal continua temprana con un desenlace favorable en términos de supervivencia en la UCI.

Antibiotic resistance profile in intrahospital pediatric services at third level centers in Dominican Republic / Perfil de resistencia a antibióticos en servicios pediátricos intrahospitalarios en centros de tercer nivel en República Dominicana

Objectives: The Dominican Republic lacks reliable information on antimicrobial resistance (AMR), which would allow physicians to prescribe the best treatment for common infectious diseases. This study aimed to define the antimicrobial resistance profiles of the more common pathogens from pediatric services, where data is even more important due to the vulnerability of the population. Methods: We collected data from patients admitted in the pediatric unit of three third level hospitals in the city of Santiago de los Caballeros, Dominican Republic, showing positive bacterial cultures, during a period of two years. Results: Half of the Gram negative pathogens exhibited third generation cephalosporins (3GC) resistance, 17% were resistant to carbapenems. Serratia marcescens presented an exceptionally high proportion of resistance to 3GC (95.9%). Staphylococcus aureus showed elevated resistance to methicillin (58.4%) and even to clindamycin (35.8%). Conclusion: There are elevated levels of antimicrobial resistance among the Enterobacteriaceae family and the Staphylococcus genus isolated from the pediatric population. Necessary measures should be taken to tackle AMR in the country.

Objetivos: La República Dominicana carece de información confiable sobre las resistencias antimicrobianas en el país, lo que permitiría al personal médico prescribir los mejores tratamientos para infecciones comunes. El objetivo de este estudio es definir los perfiles de resistencia antimicrobiana de los patógenos más comunes en servicios pediátricos, donde esta información es esencial, debido a la vulnerabilidad de la población. Métodos: Se tomaron los datos de reportes microbiológicos con cultivo bacteriano positivo procedentes de pacientes admitidos en la unidad pediátrica de tres hospitales de tercer nivel en la ciudad de Santiago de los Caballeros, República Dominicana, durante un periodo de dos años. Resultados: La mitad de los patógenos Gram negativos mostraron resistencia a cefalosporinas de tercera generación (3GC), 17% eran resistentes a carbapenémicos. Serratia marcescens presentó una resistencia excepcionalmente elevada a 3GC (95.9%). Staphylococcus aureus mostró alta resistencia a meticilina (58.4%) e incluso a clindamicina (35.8%). Conclusión: Existen elevados niveles de resistencia antimicrobiana entre las enterobacterias y los estafilococos en la población pediátrica dominicana. Es necesario tomar medidas para abordar este problema en el país.

Characteristics of oral methicillin-resistant Staphylococcus epidermidis isolated from dental plaque / 国际口腔科学杂志·英文版

The oral microbial community is widely regarded as a latent reservoir of antibiotic resistance genes. This study assessed the molecular epidemiology, susceptibility profile, and resistance mechanisms of 35 methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from the dental plaque of a healthy human population. Broth microdilution minimum inhibitory concentrations (MICs) revealed that all the isolates were nonsusceptible to oxacillin and penicillin G. Most of them were also resistant to trimethoprim (65.7%) and erythromycin (54.3%). The resistance to multiple antibiotics was found to be largely due to the acquisition of plasmid-borne genes. The mecA and dfrA genes were found in all the isolates, mostly dfrG (80%), aacA-aphD (20%), aadD (28.6%), aphA3 (22.9%), msrA (5.7%), and the ermC gene (14.3%). Classical mutational mechanisms found in these isolates were mainly efflux pumps such as qacA (31.4%), qacC (25.7%), tetK (17.1%), and norA (8.6%). Multilocus sequence type analysis revealed that sequence type 59 (ST59) strains comprised 71.43% of the typed isolates, and the eBURST algorithm clustered STs into the clonal complex 2-II(CC2-II). The staphyloccoccal cassette chromosome mec (SCCmec) type results showed that 25 (71.43%) were assigned to type IV. Moreover, 88.66% of the isolates were found to harbor six or more biofilm-associated genes. The aap, atlE, embp, sdrF, and IS256 genes were detected in all 35 isolates. This research demonstrates that biofilm-positive multiple-antibiotic-resistant ST59-SCCmec IV S. epidermidis strains exist in the dental plaque of healthy people and may be a potential risk for the transmission of antibiotic resistance.

Left hemifacial lymphatic malformation in a nine-year-old boy

@#<p style="text-align: justify;">The diagnosis of lymphatic malformations can present problems with diagnosis and treatment. Non-response to a chosen procedure can magnify the initial problems or create new ones. We present such a case.</p><p style="text-align: justify;"> </p><p style="text-align: justify;"><strong>CASE REPORT</strong></p><p style="text-align: justify;">            A 9-year-old boy initially presented with a 3-year history of soft upper eyelid mass with red-violet discoloration after hitting his head on a wooden post. About 2 years before this presentation, progressive enlargement in size of the mass with extension to the left maxillary and left scalp region prompted an ophthalmologic consult, and Magnetic Resonance Imaging (MRI) of the orbit and Magnetic Resonance Angiography (MRA) of intracranial vessels revealed a venous-lymphatic malformation. (Figure 1) He was then referred to our institution for further management.</p><p style="text-align: justify;">            The patient was noted to have a 4x2 cm reddish vascular mass over the left eyelid with no thrill or bruit and a surrounding 9x9 cm bluish left facial swelling in the periorbital region extending to the maxillary area corresponding to the MRI images. A repeat MRI/MRA showed a prominent branch of the left external carotid artery coursing towards the mass. (Figure 2)</p><p style="text-align: justify;">An angiogram of the neck for possible coil insertion into the prominent vessel from the external carotid artery was performed by interventional radiology. However, the left common carotid, left external carotid, and left vertebral arteries showed no evidence of high- or low-flow arteriovenous malformation. (Figure 3) This favored a hypovascular, space-occupying lesion consistent with a cystic lymphatic malformation and the boy was referred back to our service for possible surgery.</p><p style="text-align: justify;">Meanwhile, the mass continuously increased in size and by the time he was seen again in our clinic, the mass measured 15x15x20 cm occupying the left hemifacial area from the midportion of the parietal bone superiorly to the body of the mandible inferiorly, with violaceous skin discoloration and verrucous infraorbital lesions. (Figure 4) The patient was not considered a good candidate for surgical excision due to the size of the mass relative to his body, and initial sclerotherapy was planned to possibly decrease the size of the mass enough for excision of any residuals.</p><p style="text-align: justify;">Percutaneous Sclerotherapy was performed using a guidewire-catheter replacement technique. An initial drainage of 800mL of non-clotting serosanguinous fluid was followed by infusion of 3% sodium tertradecyl sulfate, followed by 99% ethanol infusion. There was gross decrease in the size of the mass after the procedure. (Figure 5) A pigtail drainage catheter was maintained to continuously drain fluid from the lesion. On the 10th hospital day, the boy had febrile episodes associated with enlargement of the left hemifacial mass. Blood cultures showed no bacterial growth. Culture of the pigtail catheter tip grew Morganella morganii. Amikacin 170mg IV every 8 hours was started but fever was unrelenting. Wound cultures grew Methicillin Resistant Staphylococcus Aureus, and Co-trimoxazole 40mg/200mg per 5ml Pediatric Suspension, 10ml every 12 hours and Metronidazole 200mg/5mL oral suspension, 5mL every 8 hours were initiated.</p><p style="text-align: justify;">During this month-long post-operative period, the mass continued to expand to its preoperative size. (Figure 6) Due to lack of funds, the antibiotics were given by mouth and the patient was discharged. On 3-month follow up, the mass had grown to even larger than the pre-embolization stage.</p><p style="text-align: justify;"> <strong>DISCUSSION</strong></p><p style="text-align: justify;">            Lymphatic malformations (LM) are made up of variously dilated lymphatic channels or cysts, lined by endothelial cells with a lymphatic phenotype.1  Histologically, LM is classified into the macrocystic type, consisting of cysts larger than 2 cm with clear boundaries, and the microcystic type consisting of cysts smaller than 2 cm that appear diffuse and sprouted without clear boundaries. The two types coexist in the combined type.2  </p><p style="text-align: justify;">            A 5-stage clinicoradiologic staging system has been devised by de Serres et al. based on cervical LM laterality and relationship to the hyoid bone predicting operative risk and surgical outcome.3 The higher the clinicoradiologic stage, the greater the potential risk of intraoperative and postoperative complications.  In general, bilateral microcystic suprahyoid LMs are more difficult to treat than infrahyoid LMs, especially when there are microcystic LMs involving the oral cavity, tongue, and/or pharynx. In this case, confirming whether it was a high-flow or a low-flow disease presented a dilemma early on. We relied on the initial MRI/MRA findings of a possible arterial feeding vessel, considering that MRI/MRI is more than 90% accurate in the diagnosis of high-flow vascular anomalies.4 However, during angiography for coil insertion, there were no feeding vessels found and a low-flow disease was considered. Thus, there were further delays in management associated with these procedures.</p><p style="text-align: justify;">            In our case, the patient had a unilateral suprahyoid LM that has a complication rate of 41% with an average of 1.5 procedures to treat and cure the disease.3 The possible complications that were considered included facial nerve palsy, seroma, exsanguination and most importantly, functional compromise due to the projected large post-operative defect and location of the mass which could affect function of the left eye, feeding problems and long term facial disfigurement.5</p><p style="text-align: justify;">            Considering these possible complications, we planned to attempt initial sclerotherapy before considering surgery. However, we encountered infection of the pigtail site and wound, and sclerotherapy failed to decrease the size of the mass. At the moment, subjecting the patient to repeat sclerotherapy may have a higher chance of failure.</p><p style="text-align: justify;"><strong>            </strong>Noting that the treatment of lymphatic malformation should be directed towards preservation of functional and aesthetic integrity,5 we present our case for consideration.</p>

Chronic Recurrent Methicillin Resistant Staphylococcus Hemolyticus Endophthalmitis after Cataract Surgery

PURPOSE: To report a case of recurrent endophthalmitis due to methicillin resistant Staphylococcus hemolyticus after phacoemulsification and posterior chamber intraocular lens (IOL) implantation. CASE SUMMARY: A 76-year-old female visited our outpatient clinic with decreased vision 40 days after uncomplicated cataract surgery in her right eye. At the visit, anterior chamber inflammation and cloudy fluid between the posterior capsule and IOL were observed. Uveitis due to residual cortex of lens or capsular block syndrome was suspected, so YAG laser capsulotomy and subconjunctival injection of dexamethasone were performed. Two days later, hypopyon and vitreous opacity were seen. The patient underwent an emergency vitrectomy and intravitreal antibiotic injection with suspicion of bacterial endophthalmitis. The culture was negative. Twenty days after the vitrectomy, anterior chamber inflammation and vitreous opacity developed. The recurrence of endophthalmitis was suspected due to infection by bacteria in the surrounding tissue of the IOL, so the patient underwent an IOL and lens capsule removal with intravitreal antibiotic injection. At this time, the culture revealed methicillin resistant staphylococcus hemolyticus. Systemic and topical vancomycin was then administered, resulting in decreased inflammation. Twenty days after the IOL removal, decreased vision, anterior chamber inflammation, and vitreous opacity developed. Endophthalmitis was decreased by intravitreal antibiotic injection and topical antibiotic treatment. CONCLUSIONS: Methicillin resistant staphylococcus hemolyticus should be considered in the differential diagnosis of chronic recurrent endophthalmitis after cataract surgery.

Clinical Analysis of Staphylococcus Keratitis According to Coagulase Positivity

PURPOSE: To analyze clinical aspects in a cohort of patients with Staphylococcus keratitis according to coagulase positivity (coagulase negative Staphylococcus [CNS], coagulase positive Staphylococcus [CPS]). METHODS: Epidemiology, predisposing factors, clinical characteristics, treatment outcomes, and antibiotic susceptibility were comparatively analyzed in 138 cases of culture-proven Staphylococcus keratitis (94 eyes with CNS and 44 eyes with CPS) over 20 years (1998–2017) at Yeungnam University Hospital. Poor clinical outcomes were defined as a final corrected visual acuity <0.1, a decreased visual acuity after treatment, complications, or surgical treatment. Risk factors for poor clinical outcomes were evaluated in the total cohort and analyzed using multivariate logistic regression. RESULTS: The most common predisposing factors were corneal trauma in the CNS group (47.9%) and previous ocular surface disease in the CPS group (31.8%). No significant differences were observed in mean age, sex, previous ocular surface disease, epithelial defect size, and hypopyon between the two groups. Methicillin susceptibility (39.4% vs. 72.7%, p < 0.001) was significantly lower in the CNS group, and poor clinical outcomes (28.0% vs. 43.9%, p = 0.076) were more common in the CPS group. The significant risk factors for poor clinical outcomes were initial best-corrected visual acuity <0.1, epithelial defect size ≥ 5 mm², symptom duration ≥10 days, and hypopyon. CONCLUSIONS: No significant differences were observed in epidemiological factors and initial clinical characteristics between the two study groups, but predisposing factors and methicillin susceptibility differed between the two groups. Treatment outcomes were relatively worse in the CPS group than in the CNS group, but the difference was not statistically significant. Poor clinical outcomes were more associated with long symptom duration and poor initial clinical characteristics than with coagulase positivity.

Effect of augmented renal clearance on plasma concentration of vancomycin and treatment outcome in children with methicillin-resistant Staphylococcus aureus infection / 中国当代儿科杂志

OBJECTIVE@#To investigate the effect of augmented renal clearance (ARC) on plasma concentration of vancomycin, bacteriological outcome, and clinical outcome in children with methicillin-resistant Staphylococcus aureus (MRSA) infection treated by vancomycin.@*METHODS@#A retrospective analysis was performed for the clinical data of 60 critically ill children who were treated with vancomycin due to MRSA infection from January 2013 to July 2017 and underwent plasma concentration monitoring. According to estimated glomerular filtration rate, these children were divided into an ARC group with 19 children and a normal renal function group with 41 children. The two groups were compared in terms of the use of vancomycin, plasma concentration of vancomycin, and treatment outcome.@*RESULTS@#The children in the ARC group had an age of 1-12 years, and the ARC group had significantly higher body weight and body surface area than the normal renal function group (P0.05), but the ARC group had significantly longer length of stay in the pediatric intensive care unit (PICU) and length of hospital stay than the normal renal function group (P<0.05).@*CONCLUSIONS@#ARC can significantly reduce the trough concentration of vancomycin and prolong the length of PICU stay and the length of hospital stay in children with MRSA infection. Idividualized medication should be administered to children with ARC.

Genetic Variability of Methicillin Resistant Staphylococcus Aureus Strains Isolated from Burns Patients

OBJECTIVES: Staphylococcus aureus is a nosocomial pathogen that provides a major challenge in the healthcare environment, especially in burns units where patients are particularly susceptible to infections. In this study, we sought to determine molecular types of S. aureus isolates collected from burns patients, based on staphylococcal protein A and coagulase gene polymorphisms. METHODS: Antibiotic susceptibility testing of 89 S. aureus strains isolated from burn wounds of patients was assessed using the Kirby-Bauer disk diffusion method. Strains were characterized by spa typing, coa typing, and resistance and toxin gene profiling. RESULTS: A total of 12 different spa types were identified with the majority being t790 (18%). Panton-Valentine leucocidin encoding genes were identified in spa types t044 (5.6%), t852 (2.2%) and t008 (2.2%). The most commonly detected antibiotic resistance gene was ant (4′)-Ia (60.7%). Ten different coa types were detected and the majority of the tested isolates belonged to coa III (47.2%). All the high-level mupirocin-resistant and low-level mupirocin resistant strains belonged to coa type III. CONCLUSION: The present study illustrated that despite the high frequency of coa III and spa t790 types, the genetic background of S. aureus strains in Iranian burns patients was diverse. The findings obtained are valuable in creating awareness of S. aureus infections within burns units.

Comparación de métodos fenotípico y genotípico en la detección de Staphylococcus aureus meticilino resistente en centros hospitalarios de Pereira / Comparison between phenotype and genotype methods in the detection of Methicillin-Resistant Staphylococcus aureus in Center Hospital of Pereira

Resumen Introducción: Staphylococcus aureus es un importante patógeno, puede causar infecciones leves de piel, hasta enfermedades con compromiso vital. La aparición de Staphylococcus aureus meticilino-resistentes, MRSA; ha aumentado su resistencia antimicrobiana, especialmente a β-lactámicos; dificultando el manejo de las infecciones, aumentando las tasas de morbi-mortalidad, convirtiéndose en un problema de salud pública. La expresión fenotípica de la resistencia suele ser heterogénea, dificultando su detección en el laboratorio por métodos convencionales; lo cual, incrementa los costos en la atención hospitalaria de infecciones por MRSA. Objetivo: Comparar métodos fenotípico y genotípico para la identificación de aislamientos hospitalarios de MRSA en centros hospitalarios de Pereira. Métodos: A partir de aislamientos de S. aureus obtenidos de tres instituciones de salud de alta complejidad clasificadas como A, B y C; se determinó la resistencia a meticilina por concentración mínima inhibitoria en sistemas automatizados y el gen mecA por PCR múltiple. Resultados: La prevalencia fenotípica de MRSA fue 44,4%, la institución A presentó la mayor tasa con 48,65%. La prevalencia genotípica fue 57,4%; en las instituciones A, B y C fue 55,2%, 41,7% y 75%, respectivamente, con diferencia estadísticamente significativa (p<0.05). La sensibilidad y especificidad del método fenotípico fue 99,0% y 94,7%, respectivamente, frente al método gold estándar de la PCR. El índice Kappa fue 0,942 indicando un nivel de concordancia muy bueno entre métodos. Conclusión: La prevalencia de aislamientos MRSA en las instituciones de Pereira fue alta. Los índices de concordancia de los métodos fenotípicos demostraron que son confiables para el diagnóstico de infecciones por MRSA.

Abstract Introduction: Staphylococcus aureus is an important pathogen, can cause mild skin infections, to diseases with compromise vital. The appearance of Methicillin-Resistant Staphylococcus aureus MRSA; It has increased its antimicrobial resistance, especially to β-lactam; hampering the handling of them infections, increasing the rates of morbidity-mortality, becoming a health public problem. The phenotype expression of the resistance tend to be heterogeneous, hindering its detection in the laboratory by conventional methods; which increases costs in the hospital care of MRSA infections. Objective: To compare the phenotypes and genotypes methods for identification of hospital isolates MRSA in Pereira. Methods: From isolates of S. aureus obtained of three high complexity institutions of health classified as A, B and C; determined resistance to Methicillin by minimum inhibitory concentration in automated systems and mecA gene by multiplex PCR. Results: The phenotype prevalence of MRSA was 44.4%, the institution A presented the highest rate with 48.65%. The genotype prevalence was 57.4%; in the institutions A, B and C was 55.2%, 41.7% and 75%, respectively, with difference statistically significant (p < 0.05). The sensitivity and specificity of the phenotype method were 99.0% and 94.7%, respectively, against the gold standard of the PCR method. The Kappa index was 0,942 indicating a very good level of concordance between methods. Conclusion: The prevalence of isolates MRSA in the institutions of Pereira was high. The concordance index of phenotype methods showed that they are reliable for the diagnosis of MRSA infections.

Comparación de las características y curso clínico de la endocarditis infecciosa por Staphylococcus aureus meticilino sensible versus meticilino resistente / Characteristics and clinical course of endocarditis due to Methicillin-sensitive versus methicillin-resistant Staphylococcus aureus

Resumen Introducción: Staphylococcus aureus es uno de los agentes causales más comunes de la endocarditis infecciosa. Se reportan pocos estudios en Latinoamérica acerca de las diferencias entre los perfiles de resistencia a la meticilina. Objetivo: Describir las características y el curso clínico de los pacientes con S. aureus sensible a meticilina frente al resistente. Métodos: Estudio observacional retrospectivo, cohorte histórica de pacientes adultos con diagnóstico confirmado de endocarditis entre los años 2011 y 2015. Se seleccionaron pacientes positivos para S. aureus comparando las características y el curso clínico entre los casos S. aureus sensible a meticilina frente al resistente. Resultados: Se estudiaron 86 pacientes con endocarditis. 28 (33%) tenían infección por S. aureus. 21 (75%) tenían endocarditis por S. aureus sensible a meticilina y 7 (25%) por S. aureus resistente a meticilina. En el grupo S. aureus sensible a meticilina, 11 (52,3%) fueron infecciones asociadas a atención en salud. La mayoría de casos de S. aureus resistente a meticilina fueron (85,7%) adquiridos en comunidad. La mortalidad de endocarditis por S. aureus sensible a meticilina fue superior a la causada por el resistente (33,3% vs. 14%). Conclusiones: S. aureus sigue siendo el agente más frecuente en endocarditis, más comúnmente el sensible a la meticilina. Los eventos embólicos y la gravedad fueron mayores en S. aureus sensible a meticilina. La mayor proporción de endocarditis debido a S. aureus resistente a meticilina se adquirió en la comunidad, por lo que se sugiere iniciar cobertura empírica contra S. aureus resistente a meticilina en todo caso de endocarditis adquirida en la comunidad.

Abstract Introduction: Staphylococcus aureus is one of the most common sources of infectious endocarditis. There are few studies in Latin America that report on the differences between the methicillin resistance profiles. Objective: To describe the characteristics and clinical course of patients with methicillin-sensitive S. aureus (MSSA) compared to methicillin-resistance S. aureus (MRSA) Methods: An observational, retrospective study was conducted on a historical cohort of adult patients with a confirmed diagnosis of endocarditis between the years 2011 and 2015. Patients positive for S. aureus were selected and the characteristics and clinical course and the cases of MSSA were compared with those of MRSA. Results: A total of 86 patients with endocarditis were included, of whom 28 (33%) had an infection due to S. aureus, and 21 (75%) had endocarditis due to methicillin-sensitive S. aureus, and 7 (25%) due to MRSA. In the MSSA group, 11 (52.3%) were infections associated with health care. The majority (85.7%) of cases of MRSA were community acquired. The endocarditis mortality due to MSSA was higher than that caused by MRSA (33.3% vs. 14%). Conclusions: S. aureus continues to be the most common agent in endocarditis, with MSSA being more common. The embolic events and the severity were greater in MSSA. The majority of endocarditis due to MRSA is acquired in the community, and for this reason it is suggested starting empirical cover against MRSA in all cases of community acquired endocarditis.

Análisis MLVA y perfil de virulencia de aislamientos de Staphylococcus aureus resistentes a la meticilina adquiridos en la comunidad causantes de infecciones pediátricas en Paraguay

Staphylococcus aureus resistente a la meticilina adquirido en la comunidad (SARM-AC) es uno de los principales patógenos causantes de infecciones de piel y partes blandas, aunque también se lo implica en infecciones graves, como osteomielitis y neumonía. El objetivo de este estudio descriptivo fue determinar el tipo de cassette SCCmec, el perfil de virulencia y la variabilidad genética de 21 aislamientos de SARM-AC que infectaron a niños paraguayos en el año 2010. Se determinó por PCR el tipo de cassette SCCmec y los factores de virulencia, en tanto que la variabilidad genética se determinó por la técnica multiple locus variable analysis (MLVA). Todos los aislamientos (100%) presentaron cassette SCCmec IV; algunos portaron factores de virulencia como hla, hlb y sea (el 28,6, el 9,5 y el 4,8%, respectivamente). El análisis MLVA mostró gran variabilidad genética, con datos de antibiotipo y perfil de virulencia congruentes. Este trabajo pone de manifiesto por primera vez en Paraguay la presencia de SARM-AC portador del cassette SCCmec IV con elevada diversidad genética.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is one of the first causes of skin and soft tissue infections, and can also produce severe diseases such as osteomyelitis and pneumonia. The aim of this descriptive study was to determine the SCCmec type and virulence profile and to study the genetic diversity by MLVA analysis of 21 CA-MRSA isolates that infected Paraguayan children in 2010. The SCCmec type and virulence factors were performed by PCR and genetic diversity by MLVA (multiple locus variable analysis). All the isolates carried SCCmec cassette IV. hla, hlb and sea genes were detected in 28,6%, 9,5% and 4,8% respectively. The MLVA analysis showed high genetic diversity with congruent antibiotic resistance and virulence profiles. This study revealed the presence of CA-MRSA harbouring SCCmec IV with high genetic diversity, providing information not available in our country.

Caracterización fenotípica de cepas de Staphylococcus aureus productoras de ß-lactamasas y resistente a la meticilina / Phenotypic characterization of Staphylococcus aureus strains that produce ß-lactamases and are resistant to methicillin / Caracterização fenotípica de cepas de Staphylococcus aureus pro-dutoras de ß-lactamases e resistentes à meticilina

Introducción.Staphylococcus aureus resistente a la meticilina (SARM) es una bacteria Gram positiva que hace parte de la microbiota normal y es causa importante de infecciones de origen hospitalario o adquiridas en la comunidad.Objetivo. Caracterizar fenotípicamente los aislamientos de cepas de S. aureus productoras de ß-lacta-masas y resistentes a la meticilina (SARM), aisladas en infecciones asociadas con la atención en salud en un centro hospitalario de tercer nivel.Métodos. Se llevó a cabo un estudio observacional, descriptivo y de corte transversal, que incluyó 141 cepas aisladas de 1.761 muestras clínicas que presentaban crecimiento bacteriano, en una insti-tución de salud de II nivel de complejidad de Duitama (Boyacá). En la identificación bacteriana y en las pruebas de sensibilidad, se utilizó el método automatizado Phoenix 100™ Becton Dickinson (BD). Los fenotipos de resistencia por ß-lactamasas y a la meticilina se confirmaron siguiendo la metodología del Clinical and Laboratory Standards Institute del 2017.Resultados. De 1.761 muestras clínicas que presentaron crecimiento bacteriano, se obtuvieron 141 cepas de S. aureus, de las cuales 40 presentaron el fenotipo de resistencia por betalactamasas y 19 fueron resistentes a meticilina. Conclusión. Se revela una importante prevalencia de fenotipos de resistencia circulantes en Duitama (Boyacá), con mayor prevalencia de producción de betalactamasas y menor prevalencia del fenotipo resistente a meticilina (SARM). Esto corrobora que a nivel regional y en el municipio de Duitama, S. aureus es una importante causa de infección y constituye un problema de salud pública, el cual debe continuar siendo objeto de futuras investigaciones.

Introduction: Methicillin resistant Staphylococcus aureus (MRSA) is a Gram positive bacteria that is part of the normal flora and a major cause of infections related to medical care and associated with the community.Objective: To characterize phenotypically the resistance of S. aureus with ß-lactamases resistance and methicillin-resistant strains isolated in infections associated with health care in a tertiary hospital center.Materials and methods: An observational, descriptive cross-sectional study was carried out by analy-sis of 141 S. aureus isolates obtained from a III level health institution of Duitama (Boyacá). Bacterial identification and sensitivity tests were determined by the automated method Phoenix 100™ Becton Dickinson (BD). The phenotypes of resistance to ß-lactamases or methicillin were confirmed following the 2017methodology of the Clinical and Laboratory Standards Institute.Results: One hundred and forty-one S. aureus cultures were collected, of these 40 strains were de-termined with the resistance phenotype type ß-lactamases extended spectrum and 19 resistant to methicillin (MRSA). Conclusions: High prevalence of circulating resistance phenotypes is revealed in Duitama, with a higher prevalence of ß-lactamases and a lower prevalence of the methicillin-resistant S. aureus phe-notype (MRSA), that in the region and in the municipality Duitama is an important cause of infection and constitutes a public health problem, which should continue to be the subject of future research.

Introdução. Staphylococcus aureus resistente à meticilina (MRSA) é uma bactéria Gram-positiva que faz parte da microbiota normal e é uma causa importante de infecções de origem hospitalar ou ad-quiridas na comunidade.Objetivo. Caracterizar fenotipicamente isolados de cepas de S. aureus produtoras de ß-lactamases e resistentes à meticilina (MRSA), isolados em infecções relacionadas à assistência à saúde em um centro hospitalar de terceiro nível.Materiais e métodos. Foi realizado um estudo observacional, descritivo e transversal, que incluiu 141 cepas isoladas de 1.761 amostras clínicas que evidenciaram crescimento bacteriano, em uma ins-tituição de saúde do nível II de complexidade de Duitama (Boyacá). Na identificação bacteriana e nos testes de sensibilidade, foi utilizado o método automatizado Phoenix 100 ™ Becton Dickinson (BD). Os fenótipos de resistência para ß-lactamases e meticilina foram confirmados seguindo a metodologia do Clinical and Laboratory Standards Institute de 2017.Resultados. Das 1.761 amostras clínicas que apresentaram crescimento bacteriano, foram obtidas 141 cepas de S. aureus, das quais 40 tiveram o fenótipo de resistência às beta-lactamases e 19 resis-tiram à meticilina.Conclusão. Foi revelada uma importante prevalência de fenótipos de resistência circulante em Duitama (Boyacá), com maior prevalência de produção de beta-lactamases e menor prevalência do fenótipo resistente à meticilina (MRSA). Isso corrobora que, ao nível regional e no município de Duitama, S. aureus é uma importante causa de infecção e constitui um problema de saúde pública, que deve con-tinuar sendo objeto de pesquisas futuras.

Bases moleculares de la resistencia a meticilina en Staphylococcus aureus / Molecular basis of methicillin-resistance in Staphylococcus aureus

Resumen Desde el inicio de la era antimicrobiana se han ido seleccionando gradualmente cepas de Staphylococcus aureus resistentes a antimicrobianos de amplio uso clínico. Es así como en 1960 se describen en Inglaterra las primeras cepas resistentes a meticilina, y algunos años después son informadas en hospitales de Chile. Actualmente, S. aureus resistente a penicilinas antiestafilocóccicas es endémico en los hospitales de nuestro país y del mundo, siendo responsable de una alta morbimortalidad. La resistencia es mediada habitualmente por la síntesis de una nueva transpeptidasa, denominada PBP2a o PBP2' que posee menos afinidad por el β-lactámico, y es la que mantiene la síntesis de peptidoglicano en presencia del antimicrobiano. Esta nueva enzima se encuentra codificada en el gen mecA, a su vez inserto en un cassette cromosomal con estructura de isla genómica, de los cuales existen varios tipos y subtipos. La resistencia a meticilina se encuentra regulada, principalmente, por un mecanismo de inducción de la expresión del gen en presencia del β-lactámico, a través de un receptor de membrana y un represor de la expresión. Si bien se han descrito mecanismos generadores de resistencia a meticilina mec independientes, son categóricamente menos frecuentes.

Staphylococcus aureus isolates resistant to several antimicrobials have been gradually emerged since the beginning of the antibiotic era. Consequently, the first isolation of methicillin-resistant S. aureus occurred in 1960, which was described a few years later in Chile. Currently, S. aureus resistant to antistaphylococcal penicillins is endemic in Chilean hospitals and worldwide, being responsible for a high burden of morbidity and mortality. This resistance is mediated by the expression of a new transpeptidase, named PBP2a or PBP2', which possesses lower affinity for the β-lactam antibiotics, allowing the synthesis of peptidoglycan even in presence of these antimicrobial agents. This new enzyme is encoded by the mecA gene, itself embedded in a chromosomal cassette displaying a genomic island structure, of which there are several types and subtypes. Methicillin resistance is mainly regulated by an induction mechanism activated in the presence of β-lactams, through a membrane receptor and a repressor of the gene expression. Although mec-independent methicillin resistance mechanisms have been described, they are clearly infrequent.

Interaction study between vancomycin and liposomes containing natural compounds against methicillin-resistant Staphylococcus aureus clinical isolates

ABSTRACT The treatment of infections caused by resistant microorganisms is limited, and vancomycin (VAN) treatment failures for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia are not uncommon, even when MRSA clinical isolates are susceptible to VAN. Thus, this study proposed the association of VAN with usnic acid and ß-lapachone encapsulated into liposomes as a novel therapeutic option for infections caused by MRSA. Liposomes containing ß-lap (ß-lap-lipo) or usnic acid (UA-lipo) were prepared by the thin lipid film hydration method followed by sonication. Antimicrobial activity against MRSA clinical isolates was investigated by the microdilution method according to the Clinical and Laboratory Standards Institute (CLSI). The interaction studies were carried out using the checkerboard method and epsilometer test (Etest). The interaction between VAN and ß-lap or ß-lap-lipo was synergistic (FICI = 0.453 and FICI = 0.358, respectively). An additive interaction between VAN and UA (FICI = 0.515) was found. UA-lipo resulted in synergism with VAN (FICI = 0.276). The Etest reproduced the results obtained by the checkerboard method for approximately 82% of the analysis. Thus, the present study demonstrated that VAN in combination with UA-lipo, ß-lap or ß-lap-lipo synergistically enhanced antibacterial activity against MRSA

Recurrent Familial Furunculosis Associated with Panton-Valentine Leukocidin-Positive Methicillin-Susceptible Staphylococcus aureus ST1

Staphylococcus aureus is now a major community-acquired pathogen worldwide, notably associated with skin and soft tissue infections. Staphylococci are present in the form of colonizers or environmental contaminants at home and increase the risk of recurrent infection. We are describing recurrent familial furunculosis caused by Panton-Valentine Leukocidin-positive methicillin susceptible S. aureus ST1 in Korea. An infant, his father and mother had furunculosis due to methicillin-sensitive S. aureus (MSSA) infection with identical susceptibility patterns. ST1 accounted for all 3 isolates and they were confirmed of having agr group I. Both sec and seh were detected in all isolates using polymerase chain reaction (PCR) assays, and all isolates contained Panton-Valentine leukocidin (PVL) genes. Risk factors for the household spread of S. aureus include skin conditions and close physical contact among household members. The relationship between S. aureus colonization of household contacts and the occurrence of S. aureus infection should be studied into more detail.