ANTIBIOTIC SUSCEPTIBILITY PROFILE AND PLASMID CURING IN STAPHYLOCOCCUS AUREUS FROM CHICKEN DROPLETS IN ZARIA, NORTHWEST NIGERIA

Abstract

Staphylococcus aureus is one of the major bacterial pathogens associated with hospital, community acquired
infection and recently livestock associated methicillin resistant Staph. aureus (MRSA). The aim of this study was to
isolate and determine the antibiotic susceptibility profile and plasmid curing in Staph. aureus from chicken droplets
in Zaria. A total of 250 samples were collected from 5 poultry farms. Sample were evaluated for the presence of
staphylococci using Gram staining reaction, growth on mannitol salt agar, catalase, coagulase and DNAse tests.
Antibiotic susceptibility was carried out using disc agar diffusion method. Plasmid curing was demonstrated using
0.5mg/ml acridine orange on antibiotic resistant isolates and beta lactamase production using nitrocefin test. The
results revealed 98 Staph.aureus,88 was β- lactamase producers. Most isolates showed high resistance pattern to
tetracycline (74.7%) and ampicillin (50.4%). A high percentage of the isolates were sensitive to ciprofloxacin
90.9%, vancomycin 76.1%, pefloxacin 72.3%, and gentamycin 65.9%. The percentage of phenotypic MRSA was
39.8%. Most (97.7%) of the β- lactamase producers had multiple antibiotic resistant index ≥0.3 indicating they
originated from the environment where antibiotics are frequently used. The result of plasmid curing revealed that
ampicillin (22%), oxacillin, (19%) and gentamycin (17%) showed the highest percentage reduction in 40% of the
isolates after plasmid curing, indicating that the genes were not largely resided within the plasmid which may
suggest partial involvement of chromosome in resistance. This study shows that, there is high incidence of
Staph.aureus and high level of resistance to antibiotics which is mediated by β-lactamase and partial involvement of
R-plasmid in mediating resistance