Characteristics of antimicrobial resistance and molecular epidemiology of Staphylococcus aureus isolated from patients in intensive care units

Abstract:

ObjectiveTo study the characteristics of antimicrobial resistance and molecular epidemiology of Staphylococcus aureus (S. aureus) in the intensive care units(ICUs) of a hospital. MethodsClinical isolates of S. aureus collected from ICUs between January and December 2014 were identified and performed antimicrobial susceptibility testing, then typed by staphylococcal protein A (spa) typing and multilocus sequence typing (MLST) methods. ResultsOf 160 isolates of S. aureus, 120 (75.00%) were methicillinresistant S. aureus (MRSA). Resistance rates of  MRSA to erythromycin, clindamycin,and levofloxacin were all >80%; methicillinsensitive S. aureus (MSSA) were sensitive to cefazolin, resistance rates to erythromycin, clindamycin, and levofloxacin were 62.50%,35.00%, and 10.00%  respectively. spa typing and MLST results showed that the main types of 120 isolates of MRSA were ST239t030,ST239t037, and ST5t2460, the major epidemic strains were ST239t030 (n=105,87.50%）, and were isolated from 8 ICUs; MSSA had more types, ST59t437 were detected only from department of neurology(n=8) and department of digestive diseases（n=2）, ST6t701,ST398t3625,ST398t1793, and ST121t2092 were isolated  from departments of neurology（n=7）,  anesthesiology（n=5）, neurosurgery（n=4）,and cardiac surgery（n=4）respectively.  ConclusionIsolation rate of MRSA in ICUs in this hospital is high, ST239t030 is the main type, which prevailed in hospital; different types of MSSA have epidemic trends in various departments.