Prevalence of MRSA among Healthy Children in a City of Buenos Aires Province. Molecular Characterization of Isolates (2008

S. MURZICATO; N. GARDELLA; J. DESSE; S. DI GREGORIO; A. CUIROLO; F. SPINA MARKMAN; C. LUCHETTI; G. GUTKIND; F. CRUDO; M. MOLLERACH

San Francisco, USA

Congreso; 49th Interscience Conference on Antimicrobial Agents and Chemotherapy; 2009

American Society for Microbiology

Background: Despite de widespread emergence of CA-MRSA causing infections in our country, no studies of S. aureus carriage have been performed in Argentina.Our goal was to determine carriage rates of S. aureus and MRSA in a small city of Buenos Aires Province, using as the study the whole population of healthy children (and their contacts) who where attending to the last year of kindergarten, and characterizing molecular characterization of the recovered isolates. Methods: nasal, inguinal, axillary and pharyngeal swabs where taken from a total of 316 healthy kids. Samples where inoculated directly onto mannitol-salt agar and Chromagar MRSA plates. Antimicrobial susceptibility was performed by disc difussion tests. Detection of mecA, Panton-Valentine gene and SCCmec typing where done by PCR. MRSA isolates where genotyped by spa typing and PFGE.Results: Of 316 children evaluated, 84 carried MSSA and 14 MRSA. Contacts of these group were screened and MRSA was detected in 5/14 families. Only 2 of 14 MRSA isolates were resistant to erithromycin. All of these isolates harbored SCCmec IV and 4 carried PVL gene. By contrast, not a single contact from a control population of 25 MSSA positive children carried a CA-MRSA.8/14 CA-MRSA could be grouped into one major clonal type as detected by PFGE, which could be divided in two subtypes. One of them, including the 4 PVL positive isolates, was recovered from children attending the same institution.During the follow up, not a single case of infection caused by MRSA was registered among the studied population.Conclusions: Carriage rate was 4,5% among healthy children, and it was not always present among members of their family. The PVL positive subtype is closely related to the prevalent CA-MRSA clone, (SCCmec IV, spa 311, ST 5) causing severe CA-MRSA infections in our country.