Multidrug and vancomycin resistance among clinical isolates of Staphylococcus aureus  from different teaching hospitals in Nigeria.

Olajuyigbe Olufunmiso, Ikpehae Tolulope, Coopoosamy Roger
1. Department of Microbiology, School of Sciences and Technology, Babcock University, PMB 4005, Ilisan-Remo,
Ogun State, Nigeria.
2. Department of Nature Conservation, Faculty of Natural Sciences, Mangosuthu University of Technology, Durban,
South Africa.

Abstract
Backgrounds: Staphylococcus aureushas emerged as a major public health concern because of the occurrence of multi-drug  resistant strains. This study aimed at investigating the multi-drug and vancomycin resistance profile of S. aureusfrom different  infection sites in some teaching hospitals in Nigeria.

Methods: Swabs were collected from different infection sites from out-patients in three teaching hospitals from October 2015  to May, 2016. The antibiotic-susceptibility test was carried out with selected antibiotics usually administered anti-microbials in  the treatment of infections in these hospitals. The prevalence of multi-drug and vancomycin resistance strains of S. aureusfrom  clinical samples was determined using disk diffusion and agar dilution methods respectively.

Results: The result showed (165)82.5% of the isolates were resistant to ≥3 antibiotics tested. They were highly resistant to  ceftazidime 180(90%), cloxacillin 171(85.6%) and augmentin 167(83.3%), but susceptible to ofloxacin 150(75%), gentamicin  142(71.7%), erythromycin 122(61.1%), ceftriaxone 111(55.6%) and cefuroxime 103(51.7%). All the isolates from the HVS were  all multidrug resistant strains. While (56)90.16% were multidrug resistant (MDR) in urine samples, followed by (8)88.89% MDR  strains in sputum, (37)88.81% MDR strains in semen, (49)71.64% MDR strains in wounds and (6)60% MDR strains in ear  swabs samples. Although (147)73.5% of the isolates were vancomycin susceptible S. aureus (VSSA), (30)15% were vancomycin  intermediate resistant S. aureus(VISA) and (89)44.5% of the isolates were considered vancomycin resistant S. aureus(VRSA).

Conclusions:The high percentage of the VRSA could have resulted from compromising treatment options and inadequate antimicrobial therapy. The implication, infections caused by VRSA would be difficult to treat with vancomycin and other effective  antibiotics of clinical importance. Ensuring proper monitoring of drug administration will, therefore, enhance the legitimate role  of vancomycin as an empiric choice for both prophylaxis against and treatment of staphylococcal infections.

Keywords: Bacterial resistance, vancomycin resistant S. aureus, susceptibility studies, agar dilution