[Consolidation of a Staphylococcus aureus multiresistant clone not related to the Iberian in a hospital from Mallorca]. / Consolidación de un clon multirresistente de Staphylococcus aureus no relacionado con el clon Ibérico en un hospital de Mallorca.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) was seldom isolated in our hospital until the first outbreak in 1999. A recently documented increase in antibiotic multiresistance in MRSA strains in our setting prompted the design of this molecular epidemiology study to investigate the basis for this tendency. METHODS: All MRSA isolates from clinical samples of patients admitted from July 2002 to June 2003 were studied. Susceptibility testing was performed by disk diffusion. Clonal relatedness of MRSA isolates was determined by pulsed-field gel electrophoresis (PFGE). Results were compared with data from MRSA isolates from patients admitted to the hospital in 1999-2000. RESULTS: MRSA was isolated in 110 patients (30% of patients with S. aureus-positive cultures). PFGE detected three major clones (in 93% of patients), all of which had been present in 1999-2000, although in different proportions. Whereas the predominant clone in 1999 was clone A (clone A 63%, clone B 20%), clone B was now found to predominate (clone B 58%, clone A 19%). None of these major clones were related to the five pandemic clones, including the Iberian clone, but two of them seemed to be related to the two most prevalent clones in Spain at this time. The new predominant clone was more resistant than the others, and showed uniform resistance to ciprofloxacin, erythromycin, clindamycin, and gentamicin. CONCLUSION: In recent years, a formerly predominant MRSA clone has been replaced by a multiresistant S. aureus clone that is unrelated to the Iberian clone.

Consolidación de un clon multirresistente de Staphylococcus aureus no relacionado con el clon Ibérico en un hospital de Mallorca / Consolidation of a Staphylococcus aureus multiresistant clone not related to the Iberian in a hospital from Mallorca

INTRODUCCIÓN. El primer brote de Staphylococcus aureusresistente a meticilina (SARM) en nuestro hospital se detectó en 1999. Recientemente se ha observado un incremento de la multirresistencia asociada a SARM, lo que ha motivado la realización de un estudio de epidemiología molecular para averiguar las bases de esta tendencia. MÉTODOS. Se documentaron todos los pacientes con aislamiento de SARM en muestras clínicas ingresados entre julio de 2002 y junio de 2003. El perfil de sensibilidad antibiótica se determinó mediante difusión con discos. El estudio de epidemiología molecular se realizó por electroforesis de campo pulsado (PFGE). Se han comparado los resultados obtenidos con datos históricos de 1999-2000. RESULTADOS. Se aisló SARM en 110 pacientes (30% de los pacientes con aislamiento de S. aureus). Mediante PFGE se detectaron tres clones mayoritarios (93% de pacientes). Estos clones estaban ya presentes en el estudio previo realizado en 1999-2000, aunque con un cambio en su distribución. Mientras que en 1999-2000 el mayoritario fue el clon A (clon A, 63%; clon B, 20%), actualmente ha sido desplazado por el clon B (clon B, 58%; clon A, 19%). Ninguno de los clones mayoritarios está relacionado con los cinco clones pandémicos (incluido el Ibérico)pero dos de ellos parecen relacionados con los dos clones más frecuentemente encontrados actualmente en España. El nuevo clon mayoritario presentó de forma uniforme resistencia a ciprofloxacino, eritromicina, clindamicina y gentamicina. CONCLUSIÓN. En los últimos años se ha producido un desplazamiento de un clon de SARM inicialmente predominante por otro multirresistente no relacionado con el clon Ibérico (AU)

INTRODUCTION. Methicillin-resistant Staphylococcus aureus(MRSA) was seldom isolated in our hospital until the first outbreak in 1999. A recently documented increase inantibiotic multiresistance in MRSA strains in our setting prompted the design of this molecular epidemiology study to investigate the basis for this tendency. METHODS. All MRSA isolates from clinical samples ofpatients admitted from July 2002 to June 2003 werestudied. Susceptibility testing was performed by disk diffusion. Clonal relatedness of MRSA isolates was determined by pulsed-field gel electrophoresis (PFGE). Results were compared with data from MRSA isolates from patients admitted to the hospital in 1999-2000. RESULTS. MRSA was isolated in 110 patients (30% ofpatients with S. aureus-positive cultures). PFGE detected three major clones (in 93% of patients), all of which had been present in 1999-2000, although in different proportions. Whereas the predominant clone in 1999 was clone A (clone A 63%, clone B 20%), clone B wasnow found to predominate (clone B 58%, clone A 19%).None of these major clones were related to the fivepandemic clones, including the Iberian clone, but twoof them seemed to be related to the two most prevalentclones in Spain at this time. The new predominant clone was more resistant than the others, and showed uniform resistance to ciprofloxacin, erythromycin, clindamycin,and gentamicin. CONCLUSION. In recent years, a formerly predominant MRSA clone has been replaced by a multiresistant S. aureus clone that is unrelated to the Iberian clone (AU)