Gene homology analysis on methicillin resistant Staphylococcus aureus isolated in intensive care unit

Objective To understand the drug susceptibility and gene homology of methicillin-resistant Staphylococcus aureus (MRSA) isolates from the patients and environmental samples in intensive care unit (ICU). Methods The swabs of medical personnel hands and equipment surfaces frequently contacted in ICU were collected and ICU patients' clinical samples were taken for the culture of bacteria. The identification and drug susceptibility of the strains were tested with Vitex Compact system, the homology was detected by using enterobacterial repetitive intergenic sequence (ERIC)-PCR, the cluster analysis was performed with software NTSYS-PC 2.0.Results A total of 33 strains of S. aureus was detected from ICU patients, 16 strains were identified as MRSA, the positive rate was 48.48%. Six strains of S. aureus were isolated from ICU medical personnel hands and environment, in which 5 were MRSA (83.33%). The resistant rates of 21 strains of MRSA to vancomycin, linezolid, teicoplanin were 0. The resistant rate to penicillin was 100%, the resistant rates to ciprofloxacin, erythromycin and levofloxacin were 80%; ERIC-PCR electrophoresis results showed that the maximum molecular band was about 450 bp, the smallest molecule was about 100 bp, with different profiles for 21 different strains of MRSA. The homologies of 21 strains ranged from 46.00% to 67.00%, when homology was 68.00%, it could be divided into 3 categories, the strain 1, 2, 3, 4, 5, 6, 9, 11, 13 and 17 had close relation.Conclusion The clinical MRSA isolates in ICU were multi drug resistant, clinicians should use antibiotics according to the drug susceptibility test results; the MRSA isolates in ICU environment also showed multi drug resistance, and the resistant phenotypes had certain homogeneity with clinical isoaltes, but the gene homology had no obvious relation. The environment of ICU was a MRSA infection source.