Molecular epidemiology of MRSA isolates in the intensive care unit during a 4-year-period

Abstract

Objective: Methicillin resistant Staphylococcus aureus (MRSA) is a common cause of nosocomial infections in hospitalized patients, particularly in those who stay in intensive care unit(ICU). We aimed to compare MRSA strains isolated from ICU in order to detect relatedness between them since accurate epidemiological typing by reproducible and rapid methods is a major step in determining MRSA clones and sources of transmission for immediate infection control. Methods: From February 1998 to November 2001, 56 MRSA isolates from various clinical specimens from different patients who were hospitalized in ICU of Marmara University Hospital were included in the study. These isolates were identified as MRSA by standard methods. Genotyping analysis was done by APPCR(arbitrarily primed polymerase chain reaction). Results and conclusion: The specimens which the MRSA strains isolated were as follows: 38(67.8%) from respiratory tract(deep tracheal aspirate and sputum), 10(17.8%) from blood, 4(7.1%) from wound infection and abscess, 2(3.6%)from catheters, 1(1.8%) from urine sample and 1(1.8%) from joint fluid. By AP-PCR analysis 28/56 isolates exhibited 11 incidences of clusters throughout the study period. The longest time for a given incidence was 3 months and a given incidence affected 4 patients at most. We conclude that the AP-PCR method can easily be used in order to evaluate genotypic relatedness between MRSA isolates in our institution.