Portación nasal deStaphylococcus aureus y sus perfiles de resistencia a antibióticos en niños que viven en zonas de gran altitud del sudoeste de China / Staphylococcus aureus nasal carriage and its antibiotic resistance profiles in children in high altitude areas of Southwestern China

Antecedentes/Objetivo. Describir el perfil epidemiológico de la portación nasal de cepas de Staphylococcus aureus (S. aureus), su resistencia a antibióticos y la presencia de los genes de leucocidina de Panton-Valentine (LPV) y mecA en niños en edad escolar que viven en zonas de gran altitud del sudoeste de China. Métodos. En el estudio transversal, se analizaron hisopados nasales de estudiantes a fin de detectar S. aureus. Se realizó la prueba de la reacción en cadena de la polimerasa (RCP) para identificar los genes de LPV y mecA. Resultados. Del total de 314 niños, se detectó S. aureus en el 5,10% (16/314). La resistencia de las cepas aisladas a la penicilina, eritromicina, clindamicina, rifampicina y cefoxitina fue del 100%, 81,3%, 81,3%, 0,0% y 6,3%, respectivamente. Ninguna de las cepas mostró resistencia a la vancomicina. Se detectó la expresión del gen mecA en 3 cepas aisladas, y 10 cepas aisladas dieron resultado positivo para el gen de LPV. Conclusión. Se detectó S. Aureus en el 5,10% (16/314) de la población del estudio; el 0,96% (3 /314) presentó S. Aureus resistente a la meticilina (SARM). Además, se detectó la expresión de los genes de LPV y mecA en 10 y 3 cepas aisladas, respectivamente.

Background/Aim. To describe the epidemiological profile of nasal carriage of Staphylococcus aureus (S. aureus) strains, its antibiotic resistance and mecA and Panton Valentine leukocidin (PVL) genes presence, in school children residing in high altitude areas of Southwestern China. Methods. The cross sectional study screened nasal swabs taken from students for S. aureus. PCR was performed to identify mecA and PVL genes. Results. Of the total 314 children 5.10% (16/314) was detected S. aureus. The resistance of isolated strains to penicillin, erythromycin, clindamycin, rifampicin and cefoxitin was 100%, 81.3%, 81.3%, 0.0%, and 6.3% respectively. No strains demonstrated resistance to vancomycin; expression of mecA gene was detected in 3 isolates and 10 isolates were PVL-positive. Conclusion. S. aureus was detected in 5.10% (16/314) of the study population; 0.96% (3/314) had methicillin resistant S. aureus (MRSA); expression of the mecA and PVL genes were detected in 3 and 10 isolates respectively.

Local circulating clones of Staphylococcus aureus in Ecuador

ABSTRACT The spread of pandemic Staphylococcus aureus clones, mainly methicillin-resistant S. aureus (MRSA), must be kept under surveillance to assemble an accurate, local epidemiological analysis. In Ecuador, the prevalence of the USA300 Latin American variant clone (USA300-LV) is well known; however, there is little information about other circulating clones. The aim of this work was to identify the sequence types (ST) using a Multiple-Locus Variable number tandem repeat Analysis 14-locus genotyping approach. We analyzed 132 S. aureus strains that were recovered from 2005 to 2013 and isolated in several clinical settings in Quito, Ecuador. MRSA isolates composed 46.97% (62/132) of the study population. Within MRSA, 37 isolates were related to the USA300-LV clone (ST8-MRSA-IV, Panton-Valentine Leukocidin [PVL] +) and 10 were related to the Brazilian clone (ST239-MRSA-III, PVL−). Additionally, two isolates (ST5-MRSA-II, PVL−) were related to the New York/Japan clone. One isolate was related to the Pediatric clone (ST5-MRSA-IV, PVL−), one isolate (ST45-MRSA-II, PVL−) was related to the USA600 clone, and one (ST22-MRSA-IV, PVL−) was related to the epidemic UK-EMRSA-15 clone. Moreover, the most prevalent MSSA sequence types were ST8 (11 isolates), ST45 (8 isolates), ST30 (8 isolates), ST5 (7 isolates) and ST22 (6 isolates). Additionally, we found one isolate that was related to the livestock associated S. aureus clone ST398. We conclude that in addition to the high prevalence of clone LV-ST8-MRSA-IV, other epidemic clones are circulating in Quito, such as the Brazilian, Pediatric and New York/Japan clones. The USA600 and UK-EMRSA-15 clones, which were not previously described in Ecuador, were also found. Moreover, we found evidence of the presence of the livestock associated clone ST398 in a hospital environment.

Staphylococcus aureus adquiridos en la comunidad: caracterización clínica, fenotípica y genotípica de aislados en niños paraguayos / Community-acquired Staphylococcus aureus isolated from Paraguayan children: clinical, phenotypic and genotypic characterization

Introduction: The prevalence of Staphylococcus aureus in the community has increased, being the pediatric population the most affected. This fact highlights the need for epidemiological surveillance. Aim: To characterize clinical, phenotypic and genotypic isolates of S. aureus children’s samples with community-acquired infections, collected in hospitals of Asuncion and the Central Department, between November 2009 and December 2010. Materials and Methods: Descriptive and transverse analysis with analytical component. Clinical data collected by medical records, antibiotic susceptibility according to CLSI criteria and detection of mecA (encoding methicillin resistance) and luk-PV genes (encoding Panton Valentine leucocidin) by PCR using specific oligonucleotides. Results: 123 isolates of S. aureus, 76% came from skin and soft tissue infections and 20% from sepsis. 18.7% (n = 23) were resistant to methicillin (MRSA). The presence of the mecA gene, a variant there and the PVL was detected in 12.2 and 48 isolates respectively. 43% of MRSA (n = 10) was carrying luk-PV. The clinical and demographic differences between patients infected with MRSA or MSSA were not statistically significant. Discussion: This study constitutes the first phenotypic and genotypic characterization of S. aureus associated with pediatric patients in Paraguay.

Introducción: La prevalencia de infecciones por Staphylococcus aureus en la comunidad ha aumentado, siendo la población pediátrica la más afectada; poniendo de relieve la necesidad de una vigilancia epidemiológica. Objetivo: Caracterizar clínica, fenotípica y genotípicamente aislados de S. aureus de muestras de niños con infecciones adquiridas en la comunidad, recolectadas en hospitales de Asunción y el Departamento Central, entre noviembre de 2009 y diciembre de 2010. Materiales y Métodos: Estudio descriptivo de corte trasverso. Datos clínicos fueron recabados de fichas, la susceptibilidad a antimicrobianos se hizo según criterio del CLSI y la detección de genes mecA y luk-PV se realizó por RPC empleando oligonucleótidos específicos. Resultados: De 123 aislados de S. aureus, 76% provenían de infecciones de piel y tejidos blandos y 20% de pacientes con bacteriemias. 18,7% (n: 23) fueron resistentes a meticilina (SARM). Se detectó la presencia de genes mecA, una variante del mismo y luk-PV en 9,8%, 1,6 y 39% de los aislados, respectivamente. El 43% de los SARM (n: 10) fue portador de luk-PV. Las diferencias clínicas y demográficas entre pacientes infectados por SARM o SASM no fueron estadísticamente significativas. Discusión: Este estudio constituye la primera caracterización clínica, fenotípica y genotípica de S. aureus asociados a la comunidad en población pediátrica realizada en Paraguay.

Community-associated methicillin-resistant Staphylococcus aureus in non-outbreak skin infections

The aim of this study was to determine the prevalence of Staphylococcus aureus and risk factors for the acquisition of MRSA (Methicillin Resistant Staphylococcus aureus) as the main cause of skin and soft tissue infections. S. aureus were characterized for the presence of PVL, TSST-1 and mecA genes. SCCmec typing was carried out in mecA positive strains and PFGE was performed only in these strains. During the study period, 127 outpatients attending a dermatology clinical the Botucatu Medical School, a regional tertiary hospital in Botucatu, Sao Paulo, Brazil, were diagnosed with active skin infections. A total 66 (56.9%) S. aureus strains were isolated. The methicillin resistance gene mecA was detected in seven (10.6%) S. aureus strains. The SCCmec types detected in the seven mecA-positive S. aureus strains were type Ia in one, type II in three, and type IV in three. The PVL gene was detected in 10 (15.1%) in sensitive strains. Pulsed field gel electrophoresis revealed non-clonal diversity among the isolates. The risk factors associated with MRSA acquisition in this study were previous ciprofloxacin use and working in a healthcare environment. The risk factors indicate plausible routes of CA-MRSA transmission among the subjects studied.

Methicillin-resistant Staphylococcus aureus causes both c ommunity-associated and health care-associated infections in children at the Hospital Universitario de Santander / Staphylococcus aureus resistente a meticilina causante de infecciones comunitarias y de infecciones asociadas a la atención en salud en pacientes pediátricos del Hospital Universitario de Santander

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of infection in the pediatric population. Initially, MRSA was restricted to hospitals; however, outbreaks in the community among people without health care-related risk factors have been reported worldwide. Currently, MRSA is a frequent cause of both hospital and community-associated infections. Objective: To describe the relationships between the molecular characteristics of MRSA isolates (staphylococcal cassette chromosome mec (SCCmec) type and Panton-Valentine leukocidin (PVL) carriage) and the characteristics of infection (the origin and localization of infection) in pediatric patients at the Hospital Universitario de Santander in Bucaramanga, Colombia. Materials and methods: A total of 43 MRSA isolates were obtained from hospitalized pediatric patients. SCCmec typing (I-V), SCCmec IV subtyping and PVL carriage were determined and related to the clinical characteristics. Results: Among the MRSA isolates studied, SCCmec IVc was present in 77%, followed by 16% for SCCmec I and 2% for SCCmec IVa. Two isolates were not typeable (NT). PVL genes were carried by 88% of the MRSA isolates, including the SCCmec IVc/IVa and SCCmec I isolates. SCCmec IV caused both community-acquired infection (CAI) (47%) and nosocomial infection (HAI) (53%). SCCmec IV, PVL-positive MRSA was associated with both CAI (47%) and HAI (53%) and caused mostly SSTI and osteoarticular infection. Conclusions: These findings suggest that the presence of community-associated MRSA (CA-MRSA) (SCCmec IV and PVL positive) causes both health care-associated infection (HCAI) and nosocomial infection (HAI) in pediatric patients in Colombia.

Introducción. Staphylococcus aureus resistente a la meticilina (SARM) es un agente frecuente de infección en la población pediátrica. Aunque inicialmente las cepas de SARM estaban restringidas a los hospitales, se han reportado a nivel mundial brotes de infección por SARM en individuos sin factores de riesgo y, actualmente, SARM es una causa frecuente de infecciones hospitalarias y comunitarias. Objetivo. Describir la relación entre las características moleculares de aislamientos de SARM (casete cromosómico estafilocócico mec SCCmec y leucocidina Panton-Valentine) y el origen de la infección y su presentación clínica en pacientes pediátricos del Hospital Universitario de Santander en Bucaramanga, Colombia. Materiales y métodos. Se incluyeron 43 aislamientos de SARM obtenidos de niños hospitalizados. La clasificación del SCCmec (I-V) y la subclasificación del SCCmec-IV se realizaron en todos los aislamientos. Además, los genes de la leucocidina Panton-Valentine se detectaron mediante amplificación por PCR. Las características moleculares fueron asociadas con las características clínicas de cada paciente. Resultados. Entre los 43 SARM tipificados, el SCCmec-IVc fue el más frecuente con 77 %, seguido por el SCCmec-I con 16 % y el SCCmec-IVa con 2 %. Tres aislamientos no pudieron ser tipificados. Los genes de la leucocidina Panton Valentine se detectaron en 88 % de los SARM en aislamientos portadores del SCCmec-IVc/IVa y el SCCmec-I. Los SARM SCCmec-IV positivos para la leucocidina Panton-Valentine se asociaron con infecciones adquiridas en la comunidad (47 %) y en el hospital (53 %) con compromiso de piel y tejidos blandos, y en los casos más graves, con compromiso osteoarticular. Conclusiones. Estos resultados sugieren la presencia de cepas SARM-CO (SCCmec-IV positiva para PVL) causantes de infecciones adquiridas en la comunidad y en el medio hospitalario en pacientes pediátricos en Colombia.

Hospital-associated methicillin-resistant Staphylococcus aureus carrying the PVL gene outbreak in a Public Hospital in Rio de Janeiro, Brazil

Hospital associated methicillin-resist Staphylococcus aureus has long been associated to outbreaks in the hospital environment. In this work, we investigated an outbreak of Hospital associated methicillin-resist Staphylococcus aureus carrying the Panton-Valentine leukocidin gene, which occurred in a large community hospital in Rio de Janeiro, Brazil.

Community-acquired methicillin-resistant Staphylococcus aureus from skin and soft tissue infections (in a sample of Egyptian population): analysis of mec gene and staphylococcal cassette chromosome

BACKGROUND: Staphylococcus aureus has been recognized as an important pathogen associated with inpatients and community infections. Community-acquired methicillin-resistant S. aureus (CA-MRSA) infections commonly present as skin and soft-tissue infections (SSTIs). Treatment often includes incision and drainage with or without adjunctive antibiotics. OBJECTIVES: This study aimed to identify CA-MRSA infections both phenotypically and genotypically, to determine their spectrum of antibiotic resistance, and to establish the best scheme for molecular distinction between hospital-acquired MRSA (HA-MRSA) and CA-MRSA by staphylococcal cassette chromosome mec (SCCmec) typing and detection of Panton Valentine leukocidin (PVL). MATERIALS: 50 swabs, from skin and soft tissue of infected lesions of outpatients attending the dermatology department of the Medical School, Alexandria University, were collected. Additionally, a nasal swab was taken from every participant. METHODS: Collection of swabs from the infected skin and soft tissues, followed by laboratory testing to phenotypically and genotypically identify MRSA. Also, nasal swabs were taken from every patient to identify MRSA colonization. RESULTS: Staphylococcus aureus strains were identified in 38 (76%) of the 50 clinical isolates. 18 (47.37%) out of the 38 S. aureus strains were resistant to oxacillin and cefoxitin discs, were penicillin binding protein 2a (PBP2a) producers, and were initially diagnosed as MRSA. All of the 18 strains were definitively diagnosed as MRSA by mecA gene detection using real time PCR, while only six (33.33%) strains were PVL positive. Using the sets of primers of Zhang et al.: nine (50%) out of the 18 CA-MRSA strains were SCCmec type V, and one (5.56%) was SCCmec type IVc. Then, using the set of primers by Oliveira et al., two (25%) out of the eight untypable MRSA strains were found to be SCCmec type IV, and six (75%) remained untypable. CONCLUSIONS: CA-MRSA must be considered when treating skin and soft tissue infections, especially in developing countries. Empirical use of agents active against CA-MRSA is warranted for patients presenting with serious SSTIs.

Molecular identification and antimicrobial susceptibility of Staphylococcus aureus nasal isolates from medical students in Cartagena, Colombia

Staphylococcus aureus (SA) remains a major cause of nosocomial and community-acquired infections worldwide. Nasal carriage of this bacterium among hospital personnel constitutes an important source for nosocomial infections. A cross-sectional study enrolling the whole medical student population (n = 387) of the School of Medicine at the Universidad de Cartagena, Colombia, was conducted to evaluate the carriage rates of both methicillin sensitive-and methicillin resistant-SA, the frequency of Panton-Valentine leukocidin genes in the isolates, and risk factors associated with carriage in this selected population. After signing an informed consent, participants completed a survey related to possible risk factors for colonization, and nasal swabs were collected from anterior nares. Staphylococcus aureus strains isolated from carriers were subjected to DNA extraction and PCR assays to determine the presence of MecA and Panton-Valentine leukocidin genes. Typing of the staphylococcal chromosomal cassette was performed for methicillin resistant strains. Molecular analysis was performed for only one strain per carrier. Prevalence of carriage for methicillin sensitiveand methicillin resistant-SA was 25% and 1.6% respectively. Most of the methicillin resistant isolates carried the staphylococcal chromosomal cassette type IV and the genes for Panton-Valentine leukocidin. To determine carrier types among medical students, each participant was subjected to four additional swabs, each taken two weeks apart. 9.8% persistent carriers, 53.1% intermittent carriers, and 37.1% non-carriers of SA were found. There was no association between risk factors analyzed and carriage of the bacterium. The study was conducted from April to September 2009 and found a persistent carriage of methicillin resistant-SA strains bearing the genes for Panton-Valentine leukocidin among medical students, evidencing the potential contribution of this portion of healthcare personnel either to the spread or introduction of these strains into the healthcare environment.

A novel multiplex PCR for molecular characterization of methicillin resistant Staphylococcus aureus recovered from Jeddah, Kingdom of Saudi Arabia.

Background: Molecular characterization of staphylococcal cassette chromosome mec (SCCmec) types of methicillin-resistant Staphylococcus aureus (MRSA) is very essential for studying the epidemiology of MRSA. Objectives: This study reports two multiplex PCR for molecular typing of MRSA collected from Jeddah, Kingdom of Saudi Arabia. Materials and Methods: A total of 101 clinical isolates of strains were collected from major hospital laboratories and public health centres, Jeddah, Kingdom of Saudi Arabia during the period from August 2009 to May 2011. All the strains were tested phenotypically by conventional methods and genotypically by a novel multiplex PCR targeting at the same time S. aureus 16S rRNA, Panton - valentine leucocidin (PVL) and mecA resistance genes. All the strains were tested also by multiplex PCR for typing of SCC mec types. Results: All the 101 strains previously identified phenotypically as S. aureus with bacteriological examination were positive for amplification of 756 base pair fragments specific for 16S rRNA of S. aureus. Moreover, all the strains were positive for amplification of 1339 base pair fragments specific for mecA gene, while only 38 strains (37.6%) showed positive amplification of 433 base pair fragments specific for PVL gene. The most predominant SCC mec type among the examined isolates is type V 43 (42.5) followed by SCCmec type III 39 (38.6%). Conclusion: The newly modified multiplex PCR is rapid and sensitive method for detection of MRSA. Moreover, the most predominant SCC mec type among the examined isolates from Jeddah, King Saudi Arabia is type V (42.5%), followed by Type III (38.6%).

Prevalence of methicillin-resistant staphylococcus aureus carrying panton- valentine leukocidin gene in cutaneous infections in the city of Isfahan

Methicillin-Resistant Staphylococcus aureus [MRSA] is a major cause of Nosocomial and community infections that are becoming increasingly difficult to combat, because of emerging resistance to all classes of antibiotics. Moreover Panton-Valentine leukocidin [PVL] is an important virulence factor in S. aureus and causes white blood cell destruction, necrosis and accelerated apoptosis. The aim of this study was to determine the frequency of PVL-positive MRSA in cutaneous infections, for epidemiological purposes and also to determine antibiotic resistance of the isolates. Collectively, 56 isolates of S. aureus were obtained from Isfahan University of Medical sciences affiliated hospitals and confirmed with biochemical tests [coagulase, mannitol fermentation, and DNase]. Then polymerase chain reaction [PCR] was used to detect pvl gene. Coagulase gene was used as internal control. The antibiotic susceptibility of all isolates to methicillin was determined using disk diffusion method. Out of 56 isolates 14.3% were PVL positive that 37.5% were from abscess and 62.5% were from wound. Among all of these isolates 67.8% were MRSA and also 75% of PVL-positive isolates were MRSA. The prevalence of PVL positive MRSA in cutaneous isolates is high. Future works are necessary for a more complete understanding of distribution of these virulent isolates in nasal carriers to decrease the risk of infections.

Nasal carriage of Panton Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus in healthy preschool children / Colonización nasal de Staphylococcus aureus Meticilino Resistente portador de la Leucocidina Panton-Valentine en preescolares

Objective Determining the prevalence of nasal carriage of S. aureus, both sensitive to methicillin and resistant to it, in preschool children and evaluating the presence of Panton-Valentine leukocidin genes in the isolates. Methods This was a cross-sectional study in which cultures from anterior nares were obtained from healthy preschool children. Isolates were identified as S. aureus based on morphological and biochemical tests. Antibiotic susceptibility profiles were determined by the disk diffusion method. All the isolates were further analyzed by multiplex PCR to determine the presence of mecA and PVL genes; methicillin-resistant isolates were also SCCmec typed by multiplex PCR. Results Overall S. aureus nasal colonization prevalence was 38.5 % and 4.8 % for methicillin-resistant strains. All the methicillin-resistant isolates carried the genes for PVL; two isolates possessed the SCCmec type IV, two were SCCmec type I and one was SCCmec type II. Conclusion This study revealed high PVL-positive, methicillin-resistant S. aureus colonization prevalence in healthy preschool children from Cartagena, which may play a key role in the epidemiology of community-associated infection by methicillin-resistant S. aureus in healthy children from this particular geographical area.

Objetivo Determinar la prevalencia de colonización nasal de S. aureus, tanto sensible como resistente a meticilina, en niños preescolares y evaluar la presencia de los genes de la leucocidina Panton-Valentine en estos aislamientos. Métodos Estudio de corte transversal en el que se realizaron cultivos de flora nasal de niños preescolares. Los aislamientos fueron identificados como S. aureus con base en su morfología y pruebas bioquímicas. La susceptibilidad a antibióticos se determinó por el método de difusión en disco. Todos los aislamientos fueron analizados por PCR múltiple para determinar la presencia de los genes mecA y PVL, y para la tipificación del casete cromosómico SCCmec de los aislamientos resistentes a meticilina. Resultados La colonización nasal por S. aureus fue 38,5 %, y la de cepas meticilino-resistentes fue 4,8 %. Todos los aislamientos SARM portaban los genes para PVL, dos portaban el elemento SCCmec tipo IV, dos fueron tipo I y uno fue tipo II. Conclusión Encontramos una alta prevalencia de colonización por cepas meticilino-resistentes, PVL-positivos en la población estudiada, lo que podría jugar un papel clave en la epidemiología de las infecciones por S.aureus meticilino-resistente en esta área geográfica.