MOLECULAR CHARACTERIZATION AND ANTIBIOTIC SUSCEPTIBILITY PROFILE OF VANCOMYCIN RESISTANT STAPHYLOCOCCUS AUREUS ISOLATED FROM FROZEN CHICKEN MEATS SOLD IN NIGER STATE

Abstract

Introduction: Community-acquired Staphylococcus aureus (CA-SA) has emerged as an important

human pathogen in various parts of the world, particularly in developing nations including Nigeria.

Aim: This study investigated the incidence, antibiotic resistance patterns, biofilm formation

ability, and molecular characteristics of Staphylococcus aureus isolated from chicken meat in four

Local government area (L.G.A) of Niger states, Nigeria.

Methods: Staphylococcus aureus isolation and identification were done via inoculation on a Brain

Heart Infusion media plate containing 4% NaCl and 16SrRNA PCR, while the antimicrobial

susceptibility profile was determined by the disc diffusion method on Mueller-Hinton agar. The

phenotypic detection of Vancomycin-resistant S. aureus was carried out using the Vancomycin

Agar Screen (VAS) method. Vancomycin resistance and biofilm-forming genes were characterized

using PCR methods.

Results: A total of 188 frozen chicken meats were screened for S. aureus; 50% (94 samples) were

positive for Staphylococcus aureus. Suleja had the highest incidence of 63.8%, while Bosso had

the lowest (42.5%). The isolates were highly resistant to tetracycline {87 (92.6%)}, augmentin 61

(64.9%) and 60 (63.8%) ampicillin. The resistance rates varied among locations in the State. High

percentage of the Staphylococcus aureus isolated 80(85.1%) were susceptible to Vancomycin

(VSSA), 9(9.5%) were VISA while 1(1.1%) was VRSA. The VRSA isolates harbored the vanA

gene, while it does not habour the vanB and vanXY genes. Additionally, this isolate form biofilms

phenotypically but does not possess the adherence determinant (icaA and icaD genes respectively).

Conclusion: This study reported incidences of 50% Staphylococcus aureus with high resistant

profile to commonly prescribed antibiotics, 9.5% VISA and 1.1% VRSA in frozen chicken sold in

Niger state. The S. aureus were also observed to exhibit biofilm formation ability phenotypically

the genes encoding for adherence determinant (icaA and icaD genes respectively) were absent

when they were molecularly characteristics. This study therefore highlight the importance of

monitoring antibiotic resistance in foodborne pathogens and its implications for public health.