Molecular detection of PVL, msrA genes and antibiotic susceptibility pattern of staphylococcus aureus from skin and soft tissue infections in Zaria, Nigeria

Abstract

Skin and soft tissue infections are infections involving the non-skeletal tissues i.e., exclusive of bone, ligaments, cartilage, and fibrous tissue. The aim of this research was to isolate, determine the antibiotic susceptibility pattern and detect molecularly, PVL and msrA genes from Staphylococcus aureus isolated from skin and soft tissue infections in Zaria. Four hundred skin and soft tissue (SSTI) specimens were collected from some hospitals in Zaria and screened for the presence of Staphylococcus aureus. The male-to-female ratio of patients with SSTIs was approximately 2:1 (62.30% in male and 37.70% in female). The highest frequency of 30% was observed in the 51-60 years age group. Antibiotic susceptibility test was done on the isolates using Kirby Bauer’s Disc Diffusion Technique and it was found that the highest level of resistance of S. aureus was recorded in Ceftazidime (49.28%), followed by Chloramphenicol (28.99%), Cefoxitin (27.54%), Oxacillin (26.09%) and Linezolid (7.25%). All isolates were sensitive to Vancomycin. Molecular assay was carried out on 25 selected isolates using Panton Valentine Leukocidine (PVL which codes for Community Acquired MRSA) and macrolide efflux resistance determinant (msrA, since Hospital Acquired MRSA shows high resistance to macrolides) as gene markers. PCR amplification showed 4 positive isolates (16%) for PVL genes and 7 positive isolates (28%) for msrA. There was high rate of antibiotic resistance. Vancomycin is the drug of choice while Linezolid can be considered in its absence. There was higher prevalence in HA-MRSA than CA-MRSA. Both strains showed multi-drug resistance to antibiotics. There is need for strict antibiotic policy, continuous monitoring of antibiotic susceptibility pattern of all S. aureus and observation of infection control measures to curtail the evolution of these resistant strains. Further molecular study on S. aureus SSTIs and Methicillin-Resistant S. aureus epidemiology in future is desirable.