Molecular Epidemiology of Community Associated Methicillin Resistant Staphylococcus aureus in Argentina.

GARDELLA N; DI GREGORIO S; CUIROLO A; VON SPECHT M; GUKIND G; MOLLERACH M

Buenos Aires, Argentina

Simposio; International Symposium Advances in Biomedical Sciences.; 2008

Universidad de Friburgo - Universidad de Buenos Aires

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Distinct genetic lineages associated with community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) colonization and infection have been described Colonization by MRSA was associated with an increase in the risk of infection. In Latin America, CA-MRSA have been described in Uruguay, Brazil, and Colombia. Although generally susceptible to many antimicrobial agents other than β-lactams, community associated MRSA exhibit high virulence, due, in part, to Panton-Valentine leukocidin (PVL).  However the role of this toxin in CA-MRSA pathogenesis is a matter of much debate.   We retrospectively studied a total of 69 CA-MRSA isolates that were obtained from six healthcare centers located in the northeastern and eastern of Argentina from June 2004 to March 2006 recovered from patients suffering different infection types. Simultaneously we studied the rate of S. aureus and MRSA colonization in healthy children younger than 6 years of age who were attending to kindergarten in a city of Buenos Aires Province. Based on PFGE data, four major clones were detected among patients suffering different type of infections. Pulsotype A was the largest cluster, containing 33 isolates recovered from the 6 healthcare centers included in this study. Isolates of this group belonged to ST 5. Panton Valentine leukocidin coding gene was detected in MRSA isolates recovered from infected patients but not in isolates recovered from asymptomatic carriers.  All MRSA isolates carried SCCmec type IV. Of 316 children evaluated in the colonization study, 84 carried MSSA and 14 MRSA.. Only 2 of 14 MRSA isolates were resistant to erythromycin. All of these isolates harbored SCCmec IV and 4 carried PVL gene.   Our results should be considered as an alert for the health system since: 1-  the main clone circulating in the community possesses a genetic background (ST5) with demonstrated plasticity and efficiency to be established as prevalent in the hospital environment; and 2- it presents epidemic characteristics. 3- A variant of the main clone causing CA-MRSA infections was detected in 8/14 MRSA colonized children More surveillance studies are necessary to evaluate the extent of the dissemination of this apparently well-adapted pathogen in community infections in Argentina.