Community-acquired methicillin-resistant Staphylococcus aureus pneumonia in a children's hospital. Our ten-year experience. / Neumonía por Staphylococcus aureus resistente a meticilina adquirido de la comunidad en un hospital pediátrico. Nuestra experiencia de 10 años.

INTRODUCTION: Community-acquired methicillinresistant Staphylococcus aureus (CA-MRSA) infections have increased in recent years. CAMRSA necrotizing pneumonia and empyema are now more common in children. OBJECTIVES: To determine the prevalence of CA-MRSA pneumonia and its clinical and epidemiological characteristics compared to Streptococcus pneumoniae (SP) pneumonia in the same population. MATERIAL AND METHODS: Descriptive, observational, cross-sectional study of patients hospitalized due to CA-MRSA pneumonia at Hospital de Niños Víctor J. Vilela (period: January 2008-December 2017). RESULTS: Out of 54 Staphylococcus aureus pneumonia cases, 46 (85 %) corresponded to CA-MRSA. The rate of CA-MRSA pneumonia ranged from 4.9/10 000 (2008) to 10/10 000 hospital discharges (2017). Sepsis/septic shock was observed in 41 %; empyema, in 96 %; pneumothorax, in 35 %; 90 % of cases required pleural drainage and 55 %, surgical debridement. Also, 65 % of patients were admitted to the intensive care unit (ICU); half of them required assisted mechanical ventilation. Two patients died. Strain resistance: 17 %, gentamicin; 13 %, erythromycin; and 11 %, clindamycin. Compared to SP pneumonia, CAMRSA pneumonia showed a higher risk for sepsis (95 % confidence interval; relative risk: 7.38; 3.32- 16.38) and admission to the ICU (RR: 4.29; 2.70- 6.83). No patient died due to SP pneumonia. CONCLUSIONS: The prevalence of CA-MRSA pneumonia doubled in the past decade. Compared to SP pneumonia, CA-MRSA pneumonia was more commonly accompanied by sepsis and septic shock, admission to the ICU, and ventilatory support requirement.

Introducción. Las infecciones por Staphylococcus aureus resistente a meticilina adquirido de la comunidad (SARM-AC) se han incrementado en los últimos años. Neumonías necrotizantes y empiemas por SARM-AC son cada vez más frecuentes en niños. Objetivos. Determinar la prevalencia de neumonías por SARM-AC y sus características clínico-epidemiológicas, en comparación con las neumonías por Streptococcus pneumoniae (SP) en la misma población. Material y métodos. Estudio descriptivo, observacional, transversal, de pacientes internados con neumonía por SARM-AC en el Hospital de Niños Víctor J. Vilela (período: 1/2008-12/2017). Resultados. De 54 neumonías por Staphylococcus aureus, 46 (el 85 %) fueron SARM-AC. El índice de neumonías por SARM-AC varió de 4,9/10 000 (2008) a 10/10 000 egresos (2017). Presentaron sepsis/shock séptico el 41 %; empiema, el 96 %; neumotórax, el 35 %; requirieron drenaje pleural el 90 % y toilette quirúrgica el 55 %. Ingresaron a Terapia Intensiva el 65 %; la mitad necesitó asistencia respiratoria mecánica. Hubo dos muertes. Resistencia de las cepas: el 17 % a gentamicina, el 13 % a eritromicina, el 11 % a clindamicina. En las neumonías por SARM-AC vs. las neumonías por SP, se observó mayor riesgo de sepsis (IC 95 %; RR 7,38; 3,32-16,38) e ingreso a Terapia Intensiva (RR 4,29; 2,70-6,83). No hubo muertes por SP. Conclusiones. La prevalencia de neumonías por SARM-AC se duplicó durante la última década. Comparadas con las neumonías por SP, las neumonías por SARM-AC se acompañaron, más frecuentemente, de cuadros de sepsis y shock séptico, ingreso a Terapia Intensiva y asistencia respiratoria.

Prior oropharyngeal colonization and ventilator-associated pneumonia.

This study evaluated the relationship between previous colonization of the oropharynx and development of ventilator-associated pneumonia through the classification of genomic fingerprint pattern by pulsed-field gel electrophoresis of both oxacillin-resistant and oxacillin-susceptible Staphylococcus aureus isolates obtained from hospitalized patients in an intensive care unit.

Prior oropharyngeal colonization and ventilator-associated pneumonia

This study evaluated the relationship between previous colonization of the oropharynx and development of ventilator-associated pneumonia through the classification of genomic fingerprint pattern by pulsed-field gel electrophoresis of both oxacillin-resistant and oxacillin-susceptible Staphylococcus aureus isolates obtained from hospitalized patients in an intensive care unit.

Prior oropharyngeal colonization and ventilator-associated pneumonia

This study evaluated the relationship between previous colonization of the oropharynx and development of ventilator-associated pneumonia through the classification of genomic fingerprint pattern by pulsed-field gel electrophoresis of both oxacillin-resistant and oxacillin-susceptible Staphylococcus aureus isolates obtained from hospitalized patients in an intensive care unit.

[Clinical features and outcome of community-acquired methicillin-resistant Staphylococcus aureus pneumonia]. / Características clínicas y pronóstico de la neumonía adquirida en la comunidad causada por Staphylococcus aureus resistente a la meticilina.

INTRODUCTION: The aim of this study is to describe the epidemiological and clinical features, treatment and prognosis of community-acquired pneumonia (CAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) in two different geographic regions where community-acquired MRSA (CA-MRSA) infections have different frequencies. METHODS: Observational study of patients admitted to two hospitals (one in Argentina, the other in Spain) between March 2008 and June 2012. RESULTS: We documented 16 cases of CAP caused by MRSA. MRSA accounted for 15 of 547 (2.7%) cases of CAP in Hospital Rodolfo Rossi and 1 of 1258 (0,08%) cases at the Hospital Universitari de Bellvitge (P ≤ .001). Most patients were young and previously healthy. Multilobar infiltrates, cavitation and skin and soft tissue involvement were frequent. All patients had positive blood cultures. Five patients required admission to the intensive care unit. Early mortality (≤ 48 hours) was 19%, and overall mortality (≤ 30 days) was 25%. CONCLUSION: CAP caused by MRSA causes high morbidity and mortality rates. It should be suspected in areas with a high prevalence of CA-MRSA infections, and especially in young and healthy patients who present with multilobar pneumonia with cavitation. Mortality is mainly related to septic shock and respiratory failure and occurs early in most cases.

Nosocomial ventilator-associated pneumonia in Cuban intensive care units: bacterial species and antibiotic resistance.

INTRODUCTION: Nosocomial pneumonia associated with use of mechanical ventilators is one of the greatest challenges confronted by intensivists worldwide. The literature associates several bacteria with this type of infection; most common in intensive care units are Acinetobacter baumannii, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and some of the Enterobacteriaceae family. OBJECTIVES: To identify the causal agents of nosocomial ventilator-associated pneumonia in patients receiving mechanical ventilation in the intensive care units of Havana's Hermanos Ameijeiras Clinical-Surgical Teaching Hospital in 2011, and to characterize their antibiotic resistance. METHODS: A cross-sectional descriptive study was conducted using hospital administrative data of quantitative cultures from positive tracheal aspirates for January through December, 2011. Records were analyzed from 77 intensive care unit patients who developed nosocomial ventilator-associated pneumonia. Variables examined were age and sex, and pathogens identified from culture of tracheal aspirate and related antibiotic susceptibility. RESULTS Species most frequently isolated were: Acinetobacter baumannii in 53 patients (68.8%), Pseudomonas aeruginosa in 34 patients (44.2%), other species of Pseudomonas in 15 patients (19.5%), and Serratia marcescens, Klebsiella pneumoniae, and Escherichia coli in 12 patients each (15.6%). Some patients presented more than one pathogen in concurrent or successive infections. Antimicrobial susceptibility testing found high percentages of resistance to antibiotics in all these pathogens. Least resistance was found to colistin. CONCLUSIONS: The prevalence of antibiotic resistance in bacteria causing nosocomial ventilator-associated pneumonia is of concern. Colistin is the drug of choice among the antibiotics reviewed, but sensitivity to other antibiotics should be assessed to search for more appropriate broad-spectrum antibiotics for treating nosocomial ventilator-associated pneumonia. Our results also suggest the need to strengthen infection control efforts, particularly in intensive care units, and to reassess compliance with quality control procedures. Multidisciplinary research involving microbiologists, epidemiologists, internists and intensivists is needed to fully understand the etiological and resistance patterns observed.

Neumonía Estafilocócica. Hospital Infantil General Milanés Tamayo, 2011 / Staphylococcic Pneumonia. General Milanés Tamayo Children´s Hospital, 2011

La neumonía estafilocócica guarda relación con la resistencia del huésped a las infecciones, y con la virulencia del microorganismo. El estafilococo es el agente de infección, que produce una amplia gama de enfermedades de gravedad extrema con riesgo para la vida. Presentamos un caso de una paciente con una neumonía por estafilococo, que su tórpida evolución la conduce a la Unidad de Cuidados Intensivos Pediátricos del Hospital Infantil General Milanés. Se concluye que la neumonía estafilocócica adquirida en la comunidad, se desarrolla con un cuadro grave, por lo que necesita de un diagnóstico precoz y oportuno(AU)

The staphylococcic pneumonia keeps a close relation with the guest ressistance to the infections, and with the virulence of the microorganism. The staphylococcus is the agent of infection that produces a wide range of illnesses of extreme severity with risks for the life. We present a case of a patient with staphylococcus pneumonia, and its torpid evolution leads to the Pediatric Intensive Care Unit of General Milanés Children´s Hospital. It was concluded that the staphylococcic pneumonia acquired in the community, is developed with severe clinical manifestations, for which it needs a precocious and oportune diagnosis(EU)

Necrotizing pneumonia in children submitted to thoracoscopy due to pleural empyema: incidence, treatment and clinical evolution.

OBJECTIVE: To assess the incidence of necrotizing pneumonia (NP) in children submitted to thoracoscopy, comparing patients with and without NP in terms of the presentation and clinical evolution. METHODS: A retrospective study of children with pleural empyema submitted to thoracoscopy. Thoracoscopy was performed in patients not previously submitted to thoracic drainage and in whom there was evidence of loculated effusion or pneumothorax, as well as in those previously submitted to thoracic drainage and in whom there was persistent pneumothorax or fever with purulent discharge. On the basis of the thoracoscopy findings, patients were distributed into two groups: those with NP (NP group) and those without (no-NP group). RESULTS: The study sample comprised 52 patients. Of the 24 patients with NP, 19 (79%) had undergone thoracic drainage prior to thoracoscopy, 11 (46%) presented with pneumothorax, and 16 (67%) developed bronchopleural fistula. In the NP group, the median drainage time and the median length of hospital stay were 18 and 19 days, respectively. Of the 28 patients without NP, 10 (36%) had undergone thoracic drainage prior to thoracoscopy, 9 (32%) presented pneumothorax, and 5 (18%) developed bronchopleural fistula. In the no-NP group, the median drainage time and the median length of hospital stay were 6 and 10 days, respectively. CONCLUSIONS: Pneumothorax should raise the suspicion of NP. Early thoracoscopy can be a valuable treatment option for NP in children because it hastens recovery in comparison with the medical treatment alone and avoids extensive late thoracotomy lung resections.

Pneumonia necrosante em crianças submetidas à toracoscopia por empiema pleural: incidência, tratamento e evolução clínica / Necrotizing pneumonia in children submitted to thoracoscopy due to pleural empyema: incidence, treatment and clinical evolution

OBJETIVO: Analisar a incidência de pneumonia necrosante (PN) em crianças submetidas a toracoscopia e comparar pacientes com e sem PN em relação às diferentes apresentações e evolução clínica. MÉTODOS: Estudo retrospectivo de crianças portadoras de empiema e submetidas a toracoscopia. A toracoscopia foi realizada em pacientes não submetidos a drenagem torácica prévia e evidência de derrame septado ou pneumotórax, assim como naqueles submetidos previamente a drenagem torácica e pneumotórax persistente ou febre e secreção purulenta. Baseado na presença de PN durante a toracoscopia, os pacientes foram divididos em dois grupos: com PN e sem PN. RESULTADOS: Participaram do estudo 52 pacientes. Dos 24 pacientes com PN, 19 (79 por cento) foram submetidos a drenagem torácica anterior à toracoscopia, 11 (46 por cento) apresentaram pneumotórax, e 16 (67 por cento) evoluíram com fístula broncopleural. Neste grupo, as medianas do tempo de drenagem e de hospitalização foram, respectivamente, 18 e 19 dias. Dos 28 pacientes sem PN, 10 (36 por cento) foram submetidos a drenagem torácica anterior à toracoscopia, 9 (32 por cento) apresentaram pneumotórax, e 5 (18 por cento) evoluíram com fístula broncopleural. Neste grupo, as medianas do tempo médio de drenagem e de hospitalização foram, respectivamente, 6 e 10 dias. CONCLUSÕES: A PN deve ser suspeitada na presença de pneumotórax. A toracoscopia precoce pode ser uma opção terapêutica de grande valor na PN da infância, pois acelera a recuperação quando comparada ao tratamento médico isolado e evita ressecções pulmonares extensas da toracotomia tardia.

OBJECTIVE: To assess the incidence of necrotizing pneumonia (NP) in children submitted to thoracoscopy, comparing patients with and without NP in terms of the presentation and clinical evolution. METHODS: A retrospective study of children with pleural empyema submitted to thoracoscopy. Thoracoscopy was performed in patients not previously submitted to thoracic drainage and in whom there was evidence of loculated effusion or pneumothorax, as well as in those previously submitted to thoracic drainage and in whom there was persistent pneumothorax or fever with purulent discharge. On the basis of the thoracoscopy findings, patients were distributed into two groups: those with NP (NP group) and those without (no-NP group). RESULTS: The study sample comprised 52 patients. Of the 24 patients with NP, 19 (79 percent) had undergone thoracic drainage prior to thoracoscopy, 11 (46 percent) presented with pneumothorax, and 16 (67 percent) developed bronchopleural fistula. In the NP group, the median drainage time and the median length of hospital stay were 18 and 19 days, respectively. Of the 28 patients without NP, 10 (36 percent) had undergone thoracic drainage prior to thoracoscopy, 9 (32 percent) presented pneumothorax, and 5 (18 percent) developed bronchopleural fistula. In the no-NP group, the median drainage time and the median length of hospital stay were 6 and 10 days, respectively. CONCLUSIONS: Pneumothorax should raise the suspicion of NP. Early thoracoscopy can be a valuable treatment option for NP in children because it hastens recovery in comparison with the medical treatment alone and avoids extensive late thoracotomy lung resections.

Management of methicillin-resistant Staphylococcus aureus pneumonia.

PURPOSE OF REVIEW: Staphylococcus aureus, and particularly methicillin-resistant Staphylococcus aureus (MRSA) has become an increasingly important etiology of pneumonia, both in healthcare and community settings. Associated with highest morbidity, mortality and costs in public health, it represents a major challenge for the management of this group of patients. RECENT FINDINGS: MRSA is one of the most common pathogens of ventilator associated pneumonia, whereas its estimated incidence for hospital acquired pneumonia, healthcare associated pneumonia and community acquired pneumonia has risen in the past decades. Although vancomycin at standard doses remains as the mainstay for its treatment, the increasing rate of treatment failure has prompted other strategies of use (more frequent administration, continuous infusion, combination therapy), and the use of newer antimicrobials, particularly linezolid, with pharmacokinetic and pharmacodynamic profiles which produce promisingly improved clinical results. SUMMARY: Overall, MRSA is an important cause of pneumonia; optimal management strategies for improving morbidity and mortality are still under development.

[Necrotizing pneumonia by community-acquired, methicillin-resistant Staphylococcus aureus in Colombia]. / Neumonía necrosante por Staphylococcus aureus extrahospitalario resistente a la meticilina: reporte de dos casos en Colombia.

The emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) as a cause of severe infections has been described in the recent years. In 2006, the first report of skin and soft tissue infection by CA-MRSA was published in Colombia. Herein, two additional cases of CA-MRSA are reported with a clinical course characterized by rapid progression, prolonged stay in the intensive care unit and complication of pneumonia with the onset of empyema. Both adult patients developed acute renal failure, and were treated with linezolide; the subsequent clinical response showed adequate treatment response. Molecular characterization of the isolates indicated the presence of the mecA gene carrying the cassette SCCmec type IV and the production of the toxin panton-valentine leukocidin.

[Risk factors associated with the presence of pneumonia in patients with brain injury]. / Factores de riesgo asociados a neumonía en pacientes con trauma craneoencefálico grave.

INTRODUCTION: Pneumonia in patients with head trauma occurs commonly; however, few data are available to evaluate the effects of the infection on the prognosis. OBJECTIVE: The incidence and microbiological findings were described, and the associated risk factors were established with the appearance of pneumonia in patients with severe brain trauma. MATERIALS AND METHODS: A prospective cohort study was conducted that included 39 patients with severe brain trauma and who required mechanical ventilation; initially, none had pneumonia. These patients were observed during a 24-month period in an attempt to discern the principal risk factors associated with the onset of pneumonia. RESULTS: Pneumonia occurred in 31 (80%) of the 39 patients, and 28 of these presented early pneumonia. The most frequent germ in patients with pneumonia was Staphylococcus aureus with a percentage of the 42.4%. In the multivariate analysis, the single statistically significant risk factor was the presence of hypotension and vasopressor support with a RR = 27.9 (95% CI = 1.0-749.9, p < 0.05). No significant differences in the days of mechanical ventilation or mortality in both groups. The major mortality-associated risk factor in patients with pneumonia was a low Glasgow score at admittance with an OR = 2.19 (95% CI 1.03 - 4.65), p < 0.05. CONCLUSIONS: The incidence of pneumonia in patients with severe brain trauma is high; however, its appearance does not affect the prognosis. The single significant risk factor was the presence of hypotension and vasopressor support.

Community-acquired staphylococcal pneumonia.

OBJECTIVE: Staphylococcal pneumonia typically presents high rates of morbidity and mortality. It typically occurs in cases of influenza (airborne transmission) or during episodes of bacteremia (blood-borne transmission). METHODS: A retrospective and descriptive study was conducted in patients admitted to our hospital between January of 1992 and December of 2003. All of he patients included had been diagnosed with community-acquired pneumonia caused by Staphylococcus aureus. All were older than 14 years of age, and none were intravenous drug users. RESULTS: Community-acquired pneumonia was identified in 332 cases, of which 24 (7.3%) were identified as cases of staphylococcal pneumonia. Age ranged from 14 to 89 years. Fifteen patients were male, and nine were female. Twelve patients met the criteria for severe pneumonia. Chest X-rays showed unilateral consolidation in 14 cases, bilateral consolidation in 10, pleural effusion in 15, rapid radiological progression of pulmonary lesions in 14, cavitation in 6 and pneumothorax in 1. Most of the patients presented comorbidities, of which diabetes mellitus was the most common. Twelve patients presented complications such as empyema and septic shock. Four patients died, translating to a mortality rate of 16.6% in our sample. CONCLUSIONS: The clinical presentation of pneumonia caused by S. aureus is similar to that of pneumonia caused by other etiological agents. Radiological findings, epidemiological data and risk factors provide important clues to the diagnosis. These factors are important for clinical suspicion, since S. aureus is not typically addressed in empirical treatment.

Pneumonia estafilocócica adquirida na comunidade / Community-acquired staphylococcal pneumonia

OBJETIVO: A pneumonia estafilocócica geralmente apresenta uma elevada taxa de morbidade e mortalidade. Normalmente ocorre em infecções por influenza (via aerógena) ou durante episódios de bacteremia (via hematogênica). MÉTODOS: Um estudo retrospectivo e descritivo foi realizado com os pacientes que foram admitidos em nosso hospital entre janeiro de 1992 e dezembro de 2003 com diagnóstico de pneumonia adquirida na comunidade causada por Staphylococcus aureus. Todos eles eram maiores de 14 anos e não usuários de drogas endovenosas. RESULTADOS: De um total de 332 casos de pneumonia adquirida na comunidade, foram encontrados 24 pacientes (7,3 por cento) com pneumonia estafilocócica. A idade mínima e máxima eram de, respectivamente, 14 anos e 89 anos. Quinze pacientes eram homens e nove eram mulheres. Doze pacientes preenchiam critérios para pneumonia grave. O radiograma de tórax evidenciou consolidação unilateral em 14 casos, bilateral em 10, derrame pleural em 15, rápida progressão radiológica das lesões pulmonares em 14, presença de cavitação em 6 e pneumotórax em 1 paciente. A maioria dos pacientes apresentou co-morbidades e diabetes mellitus foi a mais freqüente. Doze pacientes apresentaram complicações como empiema e choque séptico. Houve quatro óbitos, o que representou 16,6 por cento da amostra. CONCLUSÕES: A apresentação clínica da pneumonia causada por S. aureus é similar à apresentação das pneumonias originadas por outros agentes etiológicos. Os achados radiológicos, os dados epidemiológicos e os fatores de risco fornecem importantes indícios para o diagnóstico. Estes fatores são importantes para uma suspeição clínica, já que o S. aureus normalmente não é incluído nos tratamentos empíricos.

OBJECTIVE: Staphylococcal pneumonia typically presents high rates of morbidity and mortality. It typically occurs in cases of influenza (airborne transmission) or during episodes of bacteremia (blood-borne transmission). METHODS: A retrospective and descriptive study was conducted in patients admitted to our hospital between January of 1992 and December of 2003. All of he patients included had been diagnosed with community-acquired pneumonia caused by Staphylococcus aureus. All were older than 14 years of age, and none were intravenous drug users. RESULTS: Community-acquired pneumonia was identified in 332 cases, of which 24 (7.3 percent) were identified as cases of staphylococcal pneumonia. Age ranged from 14 to 89 years. Fifteen patients were male, and nine were female. Twelve patients met the criteria for severe pneumonia. Chest X-rays showed unilateral consolidation in 14 cases, bilateral consolidation in 10, pleural effusion in 15, rapid radiological progression of pulmonary lesions in 14, cavitation in 6 and pneumothorax in 1. Most of the patients presented comorbidities, of which diabetes mellitus was the most common. Twelve patients presented complications such as empyema and septic shock. Four patients died, translating to a mortality rate of 16.6 percent in our sample. CONCLUSIONS: The clinical presentation of pneumonia caused by S. aureus is similar to that of pneumonia caused by other etiological agents. Radiological findings, epidemiological data and risk factors provide important clues to the diagnosis. These factors are important for clinical suspicion, since S. aureus is not typically addressed in empirical treatment.

[Community-acquired methicillin-resistant Staphylococcus aureus infections in a hospital for acute diseases]. / Infecciones adquiridas en la comunidad por Staphylococcus aureus resistente a meticilina en un hospital de agudos.

Community-acquired methicillin-resistant Staphylococcus aureus infections in a hospital for acute diseases. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens associated with nosocomial infections. However, most recently, MRSA has arisen as an emerging community pathogen, causing serious infections, mainly among young patients. We herein describe 33 cases of infections caused by community-acquired MRSA (C-MRSA), diagnosed between May 2005 and June 2006, at "Eva Perón" Hospital. The isolations were retrospectively studied. Methicillin resistance was confirmed by means of the detection of the mecA gene, and the genes for two virulence factors (Panton-Valentine Leucocidin -PVL- and gamma-haemolysin) as well as the cassette mec type were screened by PCR. All the patients were previously healthy. Four patients under 12, presented bacteremia, one had serious pneumonia, and the three remaining patients had osteoarticular infections; all the patients over 12, had skin and soft tissue infections without systemic damage. The C-MRSA strains harboured cassette mec type IV, and the PVL and gamma-haemolysin genes. They were methicillin-resistant, with no other associated resistances. It is important to consider the presence of these community- acquired strains in order to develop strategies for their correct treatment.

Infecciones adquiridas en la comunidad por Staphylococcus aureus resistente a meticilina en un hospital de agudos / Community-acquired methicillin-resistant Staphylococcus aureus infections in a hospital for acute diseases

Staphylococcus aureus resistente a meticilina (SAMR) es uno de los principales agentes asociados a infecciones intrahospitalarias; sin embargo, en los últimos años ha surgido como un patógeno emergente de la comunidad, causando infecciones graves, principalmente en jóvenes. Se describen 33 casos de infecciones por SAMR de origen comunitario, diagnosticadas entre mayo de 2005 y junio de 2006 en el HIGA "Eva Perón". Se estudiaron retrospectivamente los aislamientos; se confirmó la resistencia a meticilina mediante la detección del gen mecA, se investigó la presencia de genes que codifican dos factores de virulencia (leucocidina de Panton-Valentine -LPV- y g-hemolisina) y el tipo de casete mec mediante PCR. Todos los pacientes se encontraban sanos previamente. Cuatro pacientes menores de 12 años presentaron bacteriemia, uno con neumonía grave y los 3 restantes con infección osteoarticular; todos los pacientes mayores de 12 años presentaron infecciones de piel y partes blandas sin compromiso sistémico. Se constató la presencia de casete mec tipo IV en todos los aislamientos; la resistencia a meticilina no se acompañó de resistencia a otros antimicrobianos; los aislamientos fueron portadores de genes que codifican para LPV y para g-hemolisina. Es importante considerar la presencia de estas cepas de origen comunitario a fin de elaborar estrategias para su correcto tratamiento.

Methicillin- resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens associated with nosocomial infections. However, most recently, MRSA has arisen as an emerging community pathogen, causing serious infections, mainly among young patients. We herein describe 33 cases of infections caused by community-acquired MRSA (CMRSA), diagnosed between May 2005 and June 2006, at "Eva Perón" Hospital. The isolations were retrospectively studied. Methicillin resistance was confirmed by means of the detection of the mecA gene, and the genes for two virulence factors (Panton-Valentine Leucocidin -PVL- and g-haemolysin) as well as the cassette mec type were screened by PCR. All the patients were previously healthy. Four patients under 12, presented bacteremia, one had serious pneumonia, and the three remaining patients had osteoarticular infections; all the patients over 12, had skin and soft tissue infections without systemic damage. The C-MRSA strains harboured cassette mec type IV, and the PVL and g-haemolysin genes. They were methicillin-resistant, with no other associated resistances. It is important to consider the presence of these community- acquired strains in order to develop strategies for their correct treatment.