Antibiotics Susceptibility Study of Staphylococcus aureus Isolates from Dry Catfish Sold in Some Open Markets in Zaria - Nigeria

Aim: The aim of this study was to determine the antibiotics susceptibility of Staphylococcus aureus isolated from dry catfish sold in some open markets in Zaria.

Place and Duration of Study: Department of Pharmaceutical Microbiology, Ahmadu Bello University, Zaria, from December 2017 to February 2019.

Methodology: Two hundred dry catfish samples were collected aseptically, wrapped in foil paper, packaged in clean polyethylene bags from open markets in Zaria and analysed by standard microbiological methods. Antibiotics susceptibility of the isolates was tested using the disc diffusion method. Eight antibiotics belonging to eight classes were employed in the study. The β-lactamase test was done using the acidimetric method while the plasmid curing was done by exposing the multidrug resistant isolates to varying concentrations of acridine orange in Mueller Hinton broth.

Results: From the 200 samples of dry catfish, 138 presumptive staphylococcal isolates were obtained. Amongst the 138 staphylococcal isolates out of which 109 (79%) were confirmed as Staphylococcus aureus by Microgen Staph ID kits. The susceptibility test showed that 46.8% of the S. aureus isolates were multidrug resistant. The isolates were sensitive to Gentamicin (100.0%) and Vancomycin (100.0%). The phenotypic expression of resistance showed that 27.8% of isolates were resistant to Cefoxitin, Clindamycin and Linezolid. Eighteen (35.3%) out of the total resistant isolates were β-lactamase producers. From the study, 50% of isolates resistant to Cefoxitin and Clindamycin became sensitive to the drugs after exposure to sub-MIC concentration of acridine orange solution.

Conclusion: This study showed that some S. aureus isolates from dry catfish in this study were resistant to commonly used antibiotics in the study area whereas others were sensitive this may be because of the use of these drugs in animal feeds.