Screening of essential oils against oxacillin - resistant Staphylococcus aureus strains isolated from bovine mastitis / Screening de aceites esenciales frente a Staphylococcus aureus oxacilino - resistentes extraidos de aislados de mastitis bovina

Bovine mastitis is a disease wi th far - reaching consequences for the dairy industry. Staphylococcus aureus is a pathogen that is especially resistant to antibiotics. The objective of this study was to evaluate the antimicrobial activity of the essential oils Lippia citriodora (Lam.), Thy mus vulgaris (L), and a mixture of the essential oils Lippia citriodora and Thymus vulgaris (50/50 v/v), against isolates of oxacillin - resistant Staphylococcus aureus (n=15) of positive cases of bovine mastitis. For the statistical analysis, the IBM SPSS s tatistical package was used. The mixture of essential oils ( Lippia citriodora and Thymus vulgaris (50/50 v/v)) obtained the most significant antimicrobial activity in relation to pure essential oils. It is therefore concluded that the mixture of these oils boosts their antimicrobial activity ( p <0.05). The minimum inhibitory and bactericidal concentration of this mixture for the total isolations was 12 µL/L and 25 µL/mL, respectively.

La mastitis bovina es una enfermedad de gran impacto para la industria lechera. El Staphylococcus aureus es uno de los principales patógenos, especialmente aquellos resistentes a los antibióticos. El objetivo de este estudio fue evaluar la actividad antimicrobiana de los aceites esenciales de Lippia citriodora (Lam.), Thymus vulgaris (L), y una mezcla de aceites esenciales de Lippia citriodora y Thymus vulgaris (50/50 v/v), frente a aislamientos clínicos de Staph ylococcus aureus oxacilino - resistentes (n=15) de mastitis bovina. Se utilizó p rograma estadístico IBM SPSS y se concluyó la diferencia significativa a un p <0.05. La mezcla de aceites esenciales ( Lippia citriodora y Thymus vulgaris (50/50 v/v)), obtuvo la m ayor actividad antimicrobiana en relación a los aceites esenciales puros, se concluye que la mezcla de estos aceites potencia su actividad antimicrobiana ( p <0.019). La concentración mínima inhibitoria y bactericida de esta mezcla fue del 12 µL/mL y 25 µL/m L, respectivamente, y puede ser una alternativa terapéutica.

Occurrence of high level methicillin resistance Staphylococcus aureusin patients from health facilities in Akwa Ibom State, Nigeria

Background:Methicillin resistant S. aureus(MRSA) has become a major public health predicament worldwide. This is owing to its involvement in the evolution of MDR strains and difficulty in therapeutic management of infected patients. This study was conducted to investigate the prevalence of methicillin resistance Staphylococcus aureusamong patients in two health facilities in Akwa Ibom State, Nigeria.Materials and Methods:Clinical isolates of patients from University of Uyo Teaching Hospital (UUTH), Uyo and General Hospital, Ikot Abasi (GHIA) were investigated based on the strategic location of the hospitals. The study design was a descriptive cross-sectional study. Three hundred clinical samples were collected from male and female in and out-patients of all ages and processed using standard bacteriological methods. Detection of Staphylococcus aureusand MRSAstrains were done according to standard protocols while antibiotic susceptibility testing of MRSAisolates was conducted using Kirby-Bauer disc diffusion method and interpreted following the CLSI 2021 guidelines. Results:The prevalence of MRSAstrains in this study was 42.9%. Majority of patients with MRSAwere from UUTH (44%) closely followed by patients from GHIA(40%). High antibiotics resistant rates of MRSAwere recorded for ampicillin (96.6%), ciprofloxacin (73.3%), erythromycin (63.3%) and cotrimoxazole (60%). Gentamicin and ceftriaxone sensitivity rates were 53.3% and 63.4%, respectively. Conclusion:Health facilities in the state should institute effective antimicrobial stewardship, intensify surveillance and screening of Staphylococcus aureusfor MRSAstrains to guard against dissemination of multidrug resistant strains in both hospital and community settings because of the clinical implications.

Endocarditis Infecciosa Mural Apical del Ventrículo Izquierdo: Presentación de caso clínico y revisión bibliográfica / Infectious Apical Mural Endocarditis of the Left Ventricle: Clinical case presentation and bibliographic review

RESUMEN La endocarditis mural es una forma infrecuente de infección intracardiaca que afecta al endocardio no valvular que pue- de presentarse con complicaciones similares a la endocarditis infecciosa valvular. Se recomienda la ecocardiografía para confirmar el diagnóstico cuando exista un alto índice de sospecha. Con respecto al tratamiento, existe evidencia limitada acerca de las estrategias terapéuticas en la endocarditis mural, sin embargo en la mayoría de casos reportados se recomienda iniciar antibioticoterapia dirigida asociado a una intervención quirúrgica precoz. A continuación, se presenta un caso clínico de un paciente masculino de 74 años con fenómenos embólicos sistémicos, en quien se documenta por ecocardiograma transesofágico una endocarditis mural en ápex del ventrículo izquierdo asociado a una bacteriemia por Staphylococcus aureus. Este caso pone de manifiesto la importancia de una valoración ecocardiográfica detallada de las válvulas y cámaras cardíacas ante la sospecha de una endocarditis infecciosa.

ABSTRACT Mural endocarditis is an uncommon form of intracardiac infection affecting the non valvular endocardium that can present with complications similar to valvular infective endocarditis. Echocardiography is recommended to confirm the diagnosis when there is a high index of suspicion. Regarding treatment, there is limited evidence about therapeutic strategies in mural endocarditis, however in most reported cases it is recommended to initiate targeted antibiotic therapy associated with early surgical intervention. The following is a clinical case of a 74-year-old male patient with systemic embolic phenomena, in whom a transesophageal echocardiogram documented mural endocarditis in the apex of the left ventricle associated with Staphylococcus aureus bacteremia. This case highlights the importance of a detailed echocardiographic assessment of the cardiac valves and chambers when infective endocarditis is suspected.

Celulitis facial por Staphylococcus aureus con metástasis infecciosas y evolución tórpida. Caso pediátrico / Facial cellulitis due to Staphylococcus aureus with metastatic infection and torpid course. A pediatric case report

La bacteriemia por Staphylococcus aureus se define como el aislamiento de dicho germen en al menos un cultivo de sangre. Las metástasis infecciosas se originan por diseminación hematógena y su posterior localización en un sitio distinto al órgano en donde se originó el proceso infeccioso. La prevalencia en la presentación de estos focos infecciosos secundarios es baja en la edad pediátrica, por lo que representa un desafío diagnóstico. Se presenta el caso de un paciente pediátrico con una celulitis facial por Staphylococcus aureus, con metástasis infecciosas y evolución tórpida.

Bacteremia due to Staphylococcus aureus is defined as the isolation of this microorganism in at least one blood culture. A metastatic infection is caused by the hematogenous dissemination and subsequent location of the microorganism in a site other than the one where the infection started. The prevalence of these secondary sources of infection is low in the pediatric population, which is a diagnostic challenge. Here we describe the case of a pediatric patient with facial cellulitis due to Staphylococcus aureus, with metastatic infection and torpid course.

Osteomielitis primaria de esternón / Primary sternal osteomyelitis

La osteomielitis primaria de esternón es muy infrecuente en niños, con menos de 100 casos publicados hasta la actualidad. Su presentación clínica es a menudo inespecífica, lo que causa un retraso en el diagnóstico. Se presentan dos nuevos casos de osteomielitis primaria de esternón. Ambos referían un cuadro de fiebre, malestar general, dolor torácico y rechazo del decúbito, con eritema preesternal en uno de los casos. La velocidad de sedimentación globular y la proteína C-reactiva estaban elevadas en ambos casos. El diagnóstico se confirmó mediante estudios de imagen y en un caso se aisló Staphylococcus aureus sensible a meticilina en el hemocultivo. Ambos se recuperaron sin complicaciones con tratamiento antibiótico. Debe tenerse en cuenta la osteomielitis primaria de esternón en el diagnóstico diferencial del dolor torácico, especialmente si se acompaña de fiebre, signos inflamatorios locales, intolerancia al decúbito o elevación de reactantes de fase aguda.

Primary sternal osteomyelitis is very rare in children, with less than 100 cases published to date. Its clinical presentation is often non-specific, which results in a diagnostic delay. Here we describe 2 new cases of primary sternal osteomyelitis. Both referred fever, malaise, chest pain, and refusal to lie down, with pre-sternal erythema in one of the cases. The erythrocyte sedimentation rate and C-reactive protein values were high in both cases. The diagnosis was confirmed by imaging studies; methicillin-sensitive Staphylococcus aureus was isolated in the blood culture of one of them. Both recovered without complications with antibiotic treatment. Primary sternal osteomyelitis should be considered in the differential diagnosis of chest pain, especially if accompanied by fever, local inflammatory signs, intolerance to lying down, or increased acute phase reactants.

Detection and expression of SapS, a class C nonspecific acid phosphatase with O-phospho-L- tyrosine-phosphatase activity, in Staphylococcus aureus isolates from patients with chronic osteomyelitis / Detección y expresión de SapS, una fosfatasa ácida no específica de clase C con actividad de fosfatasa O-fosfotirosina, en aislamientos de Staphylococcus aureus de pacientes con osteomielitis crónica

Introduction. The identity of Staphylococcus aureus virulence factors involved in chronic osteomyelitis remains unresolved. SapS is a class C non-specific acid phosphatase and a well-known virulence factor that has been identified in S. aureus strain 154 but in protein extracts from rotting vegetables. Objective. To identify the SapS gene and characterize the activity of SapS from S. aureus strains: 12 isolates from bone infected samples of patients treated for chronic osteomyelitis and 49 from a database with in silico analysis of complete bacterial genomes. Materials and methods. The SapS gene was isolated and sequenced from 12 S. aureus clinical isolates and two reference strains; 49 S. aureus strains and 11 coagulase-negative staphylococci were tested using in silico PCR. Culture media semi-purified protein extracts from the clinical strains were assayed for phosphatase activity with p-nitro-phenyl- phosphate, O-phospho-L-tyrosine, O-phospho-L-serine, and OphosphoL-threonine in conjunction with various phosphatase inhibitors. Results. SapS was detected in the clinical and in-silico S. aureus strains, but not in the in silico coagulase-negative staphylococci strains. Sec-type I lipoprotein-type N-terminal signal peptide sequences; secreted proteins, and aspartate bipartite catalytic domains coding sequences were found in the SapS nucleotide and amino acid sequence analysis. SapS dephosphorylated with p-nitro-phenyl-phosphate and ophosphoLtyrosine were selectively resistant to tartrate and fluoride, but sensitive to vanadate and molybdate. Conclusion. SapS gene was found in the genome of the clinical isolates and the in silico S. aureus strains. SapS shares biochemical similarities with known virulent bacterial, such as protein tyrosine phosphatases, suggesting it may be a virulence factor in chronic osteomyelitis.

Introducción. Se desconoce la identidad de los factores de virulencia de Staphylococcus aureus implicados en la osteomielitis crónica. Sin embargo, SapS, una fosfatasa ácida no específica de clase C, es un factor de virulencia reconocido y ya fue identificada en la cepa 154 de S. aureus, pero en extractos proteicos de vegetales podridos. Objetivo. Detectar el gen SapS y caracterizar la actividad de la fosfatasa SapS en cepas de S. aureus aisladas de pacientes con osteomielitis crónica y en las reportadas en una base de datos de análisis in silico de genomas bacterianos completos. Materiales y métodos. Se aisló y secuenció el gen SapS en los 12 aislamientos clínicos de S. aureus y en dos cepas de referencia; estas secuencias se analizaron junto con las secuencias de las cepas reportadas en la base de datos de genomas bacterianos: 49 cepas de S. aureus y 11 cepas de estafilococos negativos para coagulasa. Se evalúo la actividad de la fosfatasa SapS, presente en los extractos de los sobrenadantes de los cultivos de las cepas clínicas, mediante la hidrólisis de fosfato p-nitrofenil, O-fosfo-L- tirosina, O-fosfo-L serina y O-fosfo-L treonina junto con varios inhibidores de fosfatasas. Resultados. Se detectó el gen SapS en el genoma de las cepas clínicas y en las 49 cepas de S. aureus analizadas in silico, pero no en las 11 cepas de estafilococos negativos para coagulasa. La secuenciación de SapS reveló un péptido señal presente en el extremo N-terminal de proteínas extracelulares y los dominios bipartitos de aspartato (DDDD) en su sitio catalítico. SapS hidroliza selectivamente el fosfato p-nitrofenil y la O-fosfo-L-tirosina, pero es sensible a vanadato y molibdato. Conclusión. Se encontró SapS en el genoma de S. aureus de las cepas clínicas y de las cepas de simulación computacional. La SapS con actividad específica para la hidrólisis de la O-fosfo-L-tirosina comparte similitudes bioquímicas con las fosfatasas-tirosina bacterianas, por lo que puede formar parte de la red de factores de virulencia de la osteomielitis crónica.

Shock séptico en niños con bacteriemia por Staphylococcus aureus de la comunidad en un hospital pediátrico de alta complejidad / Septic shock in children with community acquired Staphylococcus aureus bacteremia in a high complexity pediatric hospital

INTRODUCCIÓN: La información disponible sobre los factores de riesgo para el desarrollo de shock séptico es escasa, especialmente en población pediátrica. OBJETIVO: Describir las características epidemiológicas y clínicas de los niños con bacteriemia adquirida en la comunidad por Staphylococcus aureus y comparar las características de los pacientes con y sin shock séptico. PACIENTES Y MÉTODOS: Estudio de cohorte retrospectivo. Criterios de inclusión: niños entre 30 días y 16 años de edad, internados en el Hospital de Pediatría Juan P. Garrahan entre enero de 2017 y diciembre de 2019 por infecciones adquiridas en la comunidad con desarrollo de S. aureus en hemocultivos. Criterios de exclusión: antecedente de internación dentro de los 3 meses previos al ingreso, vivir en una comunidad cerrada, presencia de catéter de larga permanencia, dispositivos intraventriculares o intraperitoneales. Análisis estadístico: STATA 16. RESULTADOS: Se incluyeron 142 niños. 21 niños (15%) presentaron shock séptico. En el análisis multivariado, se asociaron con shock séptico, la bacteriemia persistente (OR 7,15; IC95% 4,39-23,81; p: 0,001) y el foco secundario de infección (OR 6,72; IC 95% 2,02-22,2; p 0,002). La mortalidad relacionada con la infección fue 3,5% (5 pacientes). CONCLUSIONES: El shock séptico se asoció con la bacteriemia persistente y la presencia de focos secundarios de infección.

BACKGROUND: Available information about risk factors for the development of septic shock is scarce, especially in the pediatric population. AIM: To describe the epidemiological and clinical characteristics of children with community-acquired Staphylococcus aureus bacteremia and to compare the characteristics of children with and without septic shock. METHODS: Retrospective cohort study. Inclusion criteria: Children between 30 days and 16 years old, hospitalized in the Juan P. Garrahan Pediatric Hospital between January 2017 and December 2019 for community-acquired infections with S. aureus isolation in blood cultures. Exclusion criteria: History of hospitalization within 3 months prior to admission, living in a closed community, presence of long-term catheter, intraventricular or intraperitoneal devices. Statistical analysis: STATA 16. RESULTS: 142 children were included. 21 children (15%) experienced septic shock. On multivariate analysis, persistent bacteremia (OR 7.15, 95% CI 4.39-23.81, p: 0.001) and secondary focus of infection (OR 6.72, 95% CI 2.02-22.2, p 0.002) were associated with septic shock. The infection-related mortality rate was 3.5% (5 patients). CONCLUSIONS: Septic shock was associated with persistent bacteremia and the presence of secondary foci of infection.

Prevalencia de sepsis neonatal confirmada microbiológicamente en una maternidad de la Ciudad Autó noma de Buenos Aires / Prevalence of microbiologically confirmed neonatal sepsis at a maternity center in the City of Buenos Aires

Introducción. En neonatos internados es frecuente sospechar sepsis neonatal, pero solo en el 25 % al 30 % se confirma con cultivos positivos. La selección del esquema antibiótico basándose en la epidemiología local favorece el uso racional y minimiza sus efectos colaterales. Objetivo primario. Describir la prevalencia de sepsis precoz y tardía con rescate microbiológico y sus características clínicas. Población y método. Estudio transversal retrospectivo, realizado del 1 de enero de 2013 al 31 de diciembre de 2017, en una maternidad pública de Argentina, que incluyó todos los recién nacidos internados en la unidad con diagnóstico de sepsis precoz y tardía con rescate microbiológico, y aquellos reingresados dentro del mes de vida. Resultados. Ingresaron 3322 recién nacidos, 1296 evaluados por sospecha de sepsis precoz, cultivos positivos en 25 (1,9 %; tasa: 0,86 ‰). El 52 % eran menores de 33 semanas de edad gestacional. Microorganismos: Escherichia coli 5, Listeria monocytogenes 4, Streptococcus agalactiae (SGB) 3, Streptococcus pneumoniae 3. Sepsis tardía (tasa 8,73 ‰), el 68 % ocurridas en menores de 33 semanas. Microorganismos intrahospitalarios: Staphylococcus coagulasa negativos 115, Staphylococcus aureus 47, Escherichia coli 30, Cándida spp. 16, Enterococcus faecalis 13, Klebsiella pneumoniae 11 y Streptococcus agalactiae 10. En los reingresos: E. coli 11, S. aureus 12, SGB 3 y Haemophilus influenzae 3. Conclusiones. Se observa en el período estudiado una frecuencia de sepsis precoz similar a los reportes internacionales, con predominio de E. coli y L. monocytogenes. La tasa de sepsis tardía presentó una tendencia descendente en los años analizados, con predominio de los cocos grampositivos

Introduction. Neonatal sepsis is often suspected in hospitalized newborn infants, but only in 25­30% of cases it is confirmed via a positive culture. Selecting the antibiotics based on local epidemiology favors their rational use and minimizes their side effects. Primary objective. To describe the prevalence of early- and late-onset sepsis with microorganism isolation and their clinical characteristics. Population and method. Retrospective, cross-sectional study conducted between 01-01-2013 and 12-31-2017 in a public maternity center of Argentina in all hospitalized newborn infants with a diagnosis of early- and late-onset sepsis with microorganism isolation, and those re-admitted in their first month of life. Results. A total of 3322 newborn infants were admitted; 1296 were assessed for suspected early- onset sepsis; 25 had a positive culture (1.9%; rate: 0.86‰). Of these, 52% were born before 33 weeks of gestation. Microorganisms: Escherichia coli 5, Listeria monocytogenes 4, Streptococcus agalactiae (SGB) 3, Streptococcus pneumoniae 3. Also, 68% of late-onset sepsis cases (rate: 8.73‰) occurred in infants born before 33 weeks of gestation. Hospital-acquired microorganisms: coagulase-negative Staphylococcus 115, Staphylococcus aureus 47, Escherichia coli 30, Candida spp. 16, Enterococcus faecalis 13, Klebsiella pneumoniae 11, and Streptococcus agalactiae 10. In re-admissions: E. coli 11, S. aureus 12, SGB 3, and Haemophilus influenzae 3. Conclusions. During the study period, the frequency of early-onset sepsis was similar to international reports, with a predominance of E. coli and L. monocytogenes. The rate of late-onset sepsis showed a downward trend in the analyzed years, with a predominance of Gram-positive cocci.

Atividade in vitro de extratos e frações de Copernicia prunifera (Arecaceae) contra bactérias de importância clínica em saúde pública / In vitro activity of extracts and fractions of Copernicia prunifera (Arecaceae) against bacteria of clinical importance in public health / Actividad in vitro de extractos y fracciones de Copernicia prunifera (Arecaceae) frente a bacterias de importancia clínica en salud pública

Introdução: O aumento contínuo da resistência bacteriana aos antibióticos convencionais é um problema de importância global. Encontrar produtos como alternativas terapêuticas naturais é essencial. As plantas medicinais possuem uma composição química muito rica, que podem ser estruturalmente otimizadas e processadas em novos antimicrobianos. Objetivo: Avaliar o potencial antibacteriano frente a microrganismos humanos potencialmente patogênicos do extrato etanólico e frações de Copernicia prunifera. Metodologia: A triagem fitoquímica de plantas foi realizada usando métodos de precipitação e coloração e a atividade antibacteriana utilizando o método de difusão em disco e microdiluição em caldo contra cepas padronizadas de Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa e Staphylococcus aureus. Resultados: A triagem fitoquímica revela a presença de taninos, flavonoides, esteroides, triterpernóides, saponinas e alcaloides. Os extratos etanólico e frações da casca do caule e folhas tiveram atividade inibitória contra S. aureus e K. pneumonie com zona de inibição que variou de 7,0±1,73 a 9,33±0,58 mm pelo método de difusão em disco. Pelo método de microdiluição em caldo os extratos foram satisfatórios somente contra K. pneumoniae (CIM = 125 a 1000 µg/mL) S. aureus, P. aeruginosa e E. coli se mostraram resistentes aos testes (CIM > 1000 µg/mL). Conclusão: Esses resultados fornecem uma base para futuras investigações em modelos in vivo, para que os compostos de C. prunifera possam ser aplicados no desenvolvimento de novos agentes antimicrobianos contra K. pneumoniae.

Introduction: The continuous increase in bacterial resistance to conventional antibiotics is a problem of global importance. Finding products as natural therapeutic alternatives is essential. Medicinal plants have a very rich chemical composition, which can be structurally optimized and processed into novel antimicrobials. Objective: To evaluate the antibacterial potential against potentially pathogenic human microorganisms of the ethanolic extract and fractions of Copernicia prunifera. Methodology: Phytochemical screening of plants was performed using precipitation and staining methods and antibacterial activity using the disk diffusion and broth microdilution method against standardized strains of Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Results: Phytochemical screening reveals the presence of tannins, flavonoids, steroids, triterpernoids, saponins and alkaloids. The ethanolic extracts and fractions of stem bark and leaves had inhibitory activity against S. aureus and K. pneumonie with zone of inhibition ranging from 7.0±1.73 to 9.33±0.58 mm by disc diffusion method. By broth microdilution method the extracts were satisfactory only against K. pneumoniae (MIC = 125 to 1000 µg/mL) S. aureus, P. aeruginosa and E. coli were resistant to the tests (MIC > 1000 µg/mL). Conclusion: These results provide a basis for further investigation in in vivo models, so that compounds from C. prunifera can be applied in the development of new antimicrobial agents against K. pneumoniae.

Introducción: El continuo aumento de la resistencia bacteriana a los antibióticos convencionales es un problema de importancia mundial. Es esencial encontrar productos como alternativas terapéuticas naturales. Las plantas medicinales tienen una composición química muy rica, que puede optimizarse estructuralmente y transformarse en nuevos antimicrobianos. Objetivo: Evaluar el potencial antibacteriano frente a microorganismos humanos potencialmente patógenos del extracto etanólico y fracciones de Copernicia prunifera. Metodología: Se realizó el cribado fitoquímico de las plantas mediante los métodos de precipitación y tinción y la actividad antibacteriana mediante el método de difusión en disco y microdilución en caldo frente a cepas estandarizadas de Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa y Staphylococcus aureus. Resultados: El cribado fitoquímico revela la presencia de taninos, flavonoides, esteroides, triterpernoides, saponinas y alcaloides. Los extractos etanólicos y las fracciones de la corteza del tallo y las hojas presentaron actividad inhibitoria contra S. aureus y K. pneumonie con una zona de inhibición que osciló entre 7,0±1,73 y 9,33±0,58 mm por el método de difusión en disco. Por el método de microdilución en caldo, los extractos sólo fueron satisfactorios frente a K. pneumoniae (CMI = 125 a 1000 µg/mL). S. aureus, P. aeruginosa y E. coli fueron resistentes a las pruebas (CMI > 1000 µg/mL). Conclusiones: Estos resultados proporcionan una base para futuras investigaciones en modelos in vivo, de modo que los compuestos de C. prunifera puedan aplicarse en el desarrollo de nuevos agentes antimicrobianos contra K. pneumoniae.

Synthesis and evaluation of toxicity and antimicrobial activity of rifampicin associated with iron oxide nanoparticles

Rifampicin has broad-spectrum antimicrobial activity, but it can cause nephrotoxic and hepatotoxic damage because high doses are required. Nanosystems emerge as a perspective to improve the transport systems of this drug. In this work, iron oxide nanoparticles were synthesised, functionalized with lauric acid, and rifampicin was incorporated into the nanosystem. The samples were characterized by spectroscopic techniques: electronics in the visible ultraviolet region (UV-vis), vibrational absorption in the infrared region (IR), X-ray diffractometry (XRD), and dynamic light scattering (DSL). The toxicity of the nanocompounds and the antimicrobial activity against Staphylococcus aureus ATCC 25923 were studied by the Artemia salina lethality and disc diffusion techniques, respectively. As a result, IR analysis showed characteristic vibrations of laurate and rifampicin on the surface of the nanosystem. The presence of magnetic iron oxide was confirmed by XRD and the mean diameter of the crystallites was 8.37 nm. The hydrodynamic diameter of rifampicin associated with the nanosystem was 402 nm and that of the nanosystem without rifampicin was 57 nm. The compounds did not show toxicity to Artemia salina and the in vitro antimicrobial activity against Staphylococcus aureus was slightly decreased when rifampicin was associated with the nanosystem. In general terms, the results showed that iron oxide nanoparticles showed no toxicity and reduced the toxicity of rifampicin by 41.54% when carried compared to free rifampicin. Therefore, magnetic iron oxide nanoparticles may have the potential to act as a platform for associated drugs.

Effect of polycaprolactone nanocapsules loaded with essential oils on biofilm formation by Staphylococcus aureus strains isolated from bovine mastitis cases

Abstract Bovine infectious mastitis is largely resistant to antibacterial treatment, mainly due to mechanisms of bacterial resistance in the biofilms formed by Staphylococcus aureus. Melaleuca (MEO) and citronella essential oils (CEO) are promising agents for reducing or eliminating biofilms. Free melaleuca oil presented a medium Minimum Inhibitory Concentration (MIC) of 0.625% and a Minimum Bactericidal Concentration (MBC) of 1.250%, while free citronella oil showed medium MIC and MBC of 0.313%. Thus, free CEO and MEO demonstrate bacteriostatic and bactericidal potential. We generated polymeric nanocapsules containing MEO or CEO and evaluated their efficacy at reducing biofilms formed by S. aureus. Glass and polypropylene spheres were used as test surfaces. To compare the responses of free and encapsulated oils, strains were submitted to 10 different procedures, using free and nanoencapsulated essential oils (EOs) in vitro. We observed no biofilm reduction by MEO, free or nanoencapsulated. However, CEO nanocapsules reduced biofilm formation on glass (p=0.03) and showed a tendency to diminish biofilms on polypropylene (p=0.051). Despite nanoencapsulated CEO reducing biofilms in vitro, the formulation could be improved to modify the CEO component polarity and, including MEO, to obtain more interactions with surfaces and the biofilm matrix

Clinical and etiological characteristics of infectious vulvovaginitis in children in Zhejiang province from 2009 to 2019 / 中华儿科杂志

Objective: To explore the clinical characteristics, common pathogens in children with vulvovaginitis. Methods: This was a retrospective cases study. A total of 3 268 children with vulvovaginitis were enrolled, who visited the Department of Pediatric and Adolescent Gynecology, Children's Hospital, Zhejiang University School of Medicine from January 2009 to December 2019. Patients were divided into 3 groups according to the age of <7, 7-<10 and 10-18 years. Patients were also divided in to 4 groups according to the season of first visit. The pathogen distribution characteristics of infective vulvovaginitis were compared between the groups. Their clinical data were collected and then analyzed by χ2 test. Results: The were 3 268 girls aged (6.2±2.5) years. There were 1 728 cases (52.9%) aged <7 years, 875 cases (26.8%) aged 7-<10 years, and 665 cases (20.3%) aged 10-18 years. Of these cases, 2 253 cases (68.9%) were bacterial vulvovaginitis, 715 cases (21.9%) were fungal vulvovaginitis and 300 cases (9.2%) were vulvovaginitis infected with other pathogens. Bacterial culture of vaginal secretions was performed in 2 287 cases, and 2 287 strains (70.0%) of pathogens were detected, of which the top 5 pathogens were Streptococcus pyogenes (745 strains, 32.6%), Haemophilus influenzae (717 strains, 31.4%), Escherichia coli (292 strains, 12.8%), Staphylococcus aureus (222 strains, 9.7%) and Klebsiella pneumoniae (67 strains, 2.9%). Regarding different age groups, H.influenzae was the most common in children under 7 years of age (40.3%, 509/1 263), S.pyogenes (41.9%, 356/849) was predominantly in children aged 7 to 10 years, and E.coli was predominant in children aged 10 to 18 years (26.3%, 46/175). Susceptibility results showed that S.pyogenes was susceptible to penicillin G (610/610, 100.0%), ceftriaxone (525/525, 100.0%), and vancomycin (610/610, 100.0%); the resistance rates to erythromycin and clindamycin were 91.9% (501/545)and 90.7% (495/546), respectively. For H.influenzae, 32.5% (161/496) produced β-elactamase, and all strains were sensitive to meropenem (489/489, 100.0%) and levofloxacin (388/388, 100.0%), while 40.5% (202/499) were resistant to ampicillin. Among E.coli, all strains were sensitive to imipenem(100%, 175/175). The resistance rates of E.coli to levofloxacin and ceftriaxone were 29.1% (43/148) and 35.1% (59/168), respectively. A total of 48 strains of methicillin-resistant Staphylococcus aureus (MRSA) were isolated with a proportion of 28.3% (45/159) in 3 268 patients. The results of drug susceptibility test showed that all MRSA strains were sensitive to linezolid 100.0% (40/40), vancomycin (45/45, 100.0%), and tigecycline (36/36, 100.0%); the resistance rates of MRSA to penicillin G, erythromycin and clindamycin were 100% (45/45), 95.6% (43/45) and 88.9% (40/45), respectively. All methicillin-sensitive Staphylococcus aureus (MSSA) strains were sensitive to oxacillin (114/114, 100.0%), linezolid (94/94, 100.0%), vancomycin (114/114, 100.0%), and tigecycline (84/84, 100.0%); it's resistance rates to penicillin G, erythromycin and clindamycin were 78.1% (89/114), 59.7% (68/114) and 46.5% (53/114), respectively. The drug resistance rate of MSSA to penicillin G, erythromycin and clindamycin were lower than those of MRSA (χ²=11.71,19.74,23.95, respectively, all P<0.001). Conclusions: The age of consultation for pediatric infectious vulvovaginitis is mainly around 6 years. The most common pathogens are S.pyogenes, H.influenzae and Escherichia coli. Third generation cephalosporins can be used as the first choice of empirical anti-infection drugs. However, the results of drug susceptibility should be considered for targeted treatment.

Causative Microorganisms Isolated from Patients with Intra-Abdominal Infections and Their Drug Resistance Profiles: An 11-Year (2011-2021) Single-Center Retrospective Study / 生物医学与环境科学（英文）

OBJECTIVE@#To investigate the distribution and antimicrobial susceptibility of causative microorganisms recovered from patients with intra-abdominal infections (IAIs).@*METHODS@#A total of 2,926 bacterial and fungal strains were identified in samples collected from 1,679 patients with IAIs at the Peking Union Medical College Hospital between 2011 and 2021. Pathogenic bacteria and fungi were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing (AST) was performed using the VITEK 2 compact system and the Kirby-Bauer method. AST results were interpreted based on the M100-Ed31 clinical breakpoints of the Clinical and Laboratory Standards Institute.@*RESULTS@#Of the 2,926 strains identified, 49.2%, 40.8%, and 9.5% were gram-negative bacteria, gram-positive bacteria, and fungi, respectively. Escherichia coli was the most prevalent pathogen in intensive care unit (ICU) and non-ICU patients; however, a significant decrease was observed in the isolation of E. coli between 2011 and 2021. Specifically, significant decreases were observed between 2011 and 2021 in the levels of extended-spectrum β-lactamase (ESBL)-producing E. coli (from 76.9% to 14.3%) and Klebsiella pneumoniae (from 45.8% to 4.8%). Polymicrobial infections, particularly those involving co-infection with gram-positive and gram-negative bacteria, were commonly observed in IAI patients. Moreover, Candida albicans was more commonly isolated from hospital-associated IAI samples, while Staphylococcus epidermidis had a higher ratio in community-associated IAIs. Additionally, AST results revealed that most antimicrobial agents performed better in non-ESBL-producers than in ESBL-producers, while the overall resistance rates (56.9%-76.8%) of Acinetobacter baumanmii were higher against all antimicrobial agents than those of other common gram-negative bacteria. Indeed, Enterococcus faecium, Enterococcus faecalis, S. epidermidis, and S. aureus were consistently found to be susceptible to vancomycin, teicoplanin, and linezolid. Similarly, C. albicans exhibited high susceptibility to all the tested antifungal drugs.@*CONCLUSION@#The distribution and antimicrobial susceptibility of the causative microorganisms from patients with IAIs were altered between 2011 and 2021. This finding is valuable for the implementation of evidence-based antimicrobial therapy and provides guidance for the control of hospital infections.

In vitro antibacterial and antibiofilm activities of Piper betle L. ethanolic leaf extract on staphylococcus aureus ATCC 29213

Background and Objective@#Staphylococcus aureus is the leading cause of skin and soft tissue infections such as abscesses, furuncles, and cellulitis. Biofilm forming strains of S. aureus have higher incidence of antimicrobial resistance to at least three or more antibiotics and are considered as multidrug resistant. Since S. aureus biofilm-producing strains have higher rates of multidrug and methicillin resistance compared to non-biofilm-producing strains, the need for alternative therapeutic option is important. Furthermore, rates of methicillin-resistant Staphylococcus aureus (MRSA) in Asia remain high. Results of the study may provide support for the clinical uses of P. betle as a topical antibacterial and antiseptic in the treatment and prevention of infections involving the skin, mouth, throat, and indwelling medical devices. Thus, this study aimed to evaluate the in vitro antibacterial and antibiofilm activities of Piper betle L. ethanolic leaf extract (PBE) against a biofilm-forming methicillin-sensitive Staphylococcus aureus ATCC 29213 (MSSA).@*Methods@#The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PBE against MSSA were determined using the agar dilution assay. The biofilm inhibition and eradication assays using crystal violet were done to quantify the antibiofilm activities of PBE on MSSA biofilm.@*Results@#PBE showed activity against MSSA in agar dilution assay with MIC and MBC values of 2500 μg/mL and 5000 μg/mL, respectively. At subinhibitory concentrations, PBE showed biofilm inhibition activity at 1250 μg/mL but a lower percent eradication of biofilms as compared to oxacillin was noted.@*Conclusion@#PBE showed antibacterial activities including biofilm inhibition against methicillin-sensitive Staphylococcus aureus ATCC 29213 (MSSA).

Screening of pathogenic molecular markers of Staphylococcus aureus in children based on whole genome sequencing technology / 中国当代儿科杂志

OBJECTIVES@#To explore the molecular characteristics of Staphylococcus aureus (S. aureus) in children, and to compare the molecular characteristics of different types of strains (infection and colonization strains) so as to reveal pathogenic molecular markers of S. aureus.@*METHODS@#A cross-sectional study design was used to conduct nasopharyngeal swab sampling from healthy children in the community and clinical samples from infected children in the hospital. Whole genome sequencing was used to detect antibiotic resistance genes and virulence genes. A random forest method to used to screen pathogenic markers.@*RESULTS@#A total of 512 S. aureus strains were detected, including 272 infection strains and 240 colonization strains. For virulence genes, the carrying rates of enterotoxin genes (seb and sep), extracellular enzyme coding genes (splA, splB, splE and edinC), leukocytotoxin genes (lukD, lukE, lukF-PV and lukS-PV) and epidermal exfoliating genes (eta and etb) in infection strains were higher than those in colonization strains. But the carrying rates of enterotoxin genes (sec, sec3, seg, seh, sei, sel, sem, sen, seo and seu) were lower in infection strains than in colonization strains (P<0.05). For antibiotic resistance genes, the carrying rates of lnuA, lnuG, aadD, tetK and dfrG were significantly higher in infection strains than in colonization strains (P<0.05). The accuracy of cross-validation of the random forest model for screening pathogenic markers of S. aureus before and after screening was 69% and 68%, respectively, and the area under the curve was 0.75 and 0.70, respectively. The random forest model finally screened out 16 pathogenic markers (sem, etb, splE, sep, ser, mecA, lnuA, sea, blaZ, cat(pC233), blaTEm-1A, aph(3')-III, ermB, ermA, ant(9)-Ia and ant(6)-Ia). The top five variables in the variable importance ranking were sem (OR=0.40), etb (OR=3.95), splE (OR=1.68), sep (OR=3.97), and ser (OR=1.68).@*CONCLUSIONS@#The random forest model can screen out pathogenic markers of S. aureus and exhibits a superior predictive performance, providing genetic evidence for tracing highly pathogenic S. aureus and conducting precise targeted interventions.

Population structure of food-borne Staphylococcus aureus in China / 中华流行病学杂志

Objective: To understand the population structure of food-borne Staphylococcus (S.) aureus in China. Methods: Whole genome sequencing was used to analyze 763 food-borne S. aureus strains from 16 provinces in China from 2006 to 2020. Multilocus sequence typing (MLST), staphylococcal protein A gene (spa) typing, and staphylococcal chromosome cassettemec (SCCmec) typing were conducted, and minimum spanning tree based on ST types (STs) was constructed by BioNumerics 7.5 software. Thirty-one S. aureus strains isolated from imported food products were also included in constructing the genome phylogenetic tree. Results: A total of 90 STs (20 novel types) and 160 spa types were detected in the 763 S. aureus isolates. The 72 STs (72/90, 80.0%) were related to 22 clone complexes. The predominant clone complexes were CC7, CC1, CC5, CC398, CC188, CC59, CC6, CC88, CC15, and CC25, accounting for 82.44% (629/763) of the total. The STs and spa types in the predominant clone complexes changed over the years. The methicillin-resistant S. aureus (MRSA) detection rate was 7.60%, and 7 SCCmec types were identified. The ST59-t437-Ⅳa (17.24%, 10/58), ST239-t030-Ⅲ (12.07%, 7/58), ST59-t437-Ⅴb (8.62%, 5/58), ST338-t437-Ⅴb (6.90%, 4/58) and ST338-t441-Ⅴb (6.90%, 4/58) were the main types in MRSA strains. The genome phylogenetic tree had two clades, and the strains with the same CC, ST, and spa types clustered together. All CC7 methicillin sensitive S. aureus strains were included in Clade1, while 21 clone complexes and all MRSA strains were in Clade2. The MRSA strains clustered according to the SCCmec and STs. The strains from imported food products in CC398, CC7, CC30, CC12, and CC188 had far distances from Chinese strains in the tree. Conclusions: In this study, the predominant clone complexes of food-borne strains were CC7, CC1, CC5, CC398, CC188, CC59, CC6, CC88, CC15, and CC25, which overlapped with the previously reported clone complexes of hospital and community-associated strains in China, suggesting that close attention needs to be paid to food, a vehicle of pathogen transmission in community and food poisoning.

Bacteriological analysis of nasal secretions in patients with nasal lymphoma / 临床耳鼻咽喉头颈外科杂志

Objective:To investigate the etiological characteristics of nasal bacterial infection in patients with nasal lymphoma. Methods:The results of bacterial culture of nasal secretions from 39 healthy people and 86 patients with nasal lymphoma in the Affiliated Hospital of Qingdao University from January 2019 to June 2022 were retrospectively analyzed, and the differences in nasal bacteria distribution between nasal lymphoma and healthy people were analyzed and compared. Results:Corynebacterium（38.90%） was the most common bacteria in the nasal cavity of healthy people, followed by coagulase-negative Staphylococcus（31.95%）, Staphylococcus epidermidis（15.28%） and Staphylococcus aureus（6.95%）. The most common bacteria in nasal lymphoma patients was Staphylococcus aureus（30.37%）, followed by Corynebacterium（9.63%）, Staphylococcus epidermidis（7.41%） and coagulase negative Staphylococcus（6.67%）. A total of 81 nasal lymphoma patients were detected with bacteria, positive rate is as high as 94.19%（81/86）. Conclusion:Staphylococcus aureus is the main pathogenic bacteria in nasal secretion of patients with nasal lymphoma, which provides guiding significance for the clinical prevention and treatment of nasal lymphoma complicated with infection or not.

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 .

On-Site Assessment of a Cryogenic Disinfectant for the Alpine Environment and Outer Packaging of Frozen Items / 生物医学与环境科学（英文）

OBJECTIVE@#To study the effectiveness and feasibility of cryogenic disinfectants in different cold scenarios and analyze the key points of on-site cryogenic disinfection.@*METHODS@#Qingdao and Suifenhe were selected as application sites for the manual or mechanical spraying of cryogenic disinfectants. The same amount of disinfectant (3,000 mg/L) was applied on cold chain food packaging, cold chain containers, transport vehicles, alpine environments, and article surfaces. The killing log value of the cryogenic disinfectant against the indicator microorganisms ( Staphylococcus aureus and Escherichia coli) was used to evaluate the on-site disinfection effect.@*RESULTS@#When using 3,000 mg/L with an action time of 10 min on the ground in alpine regions, the surface of frozen items, cold-chain containers, and cold chain food packaging in supermarkets, all external surfaces were successfully disinfected, with a pass rate of 100%. The disinfection pass rates for cold chain food packaging and cold chain transport vehicles of centralized supervised warehouses and food processing enterprises were 12.5% (15/120), 81.67% (49/60), and 93.33% (14/15), respectively; yet, the surfaces were not fully sprayed.@*CONCLUSION@#Cryogenic disinfectants are effective in disinfecting alpine environments and the outer packaging of frozen items. The application of cryogenic disinfectants should be regulated to ensure that they cover all surfaces of the disinfected object, thus ensuring effective cryogenic disinfection.