Antibiogram of Staphylococcal Isolates and Molecular Characterisation of Coagulase Negative Staphylococci Obtained from a Hospital in Port Harcourt, Nigeria

Abstract

Difficulty in the treatment and eradication of bacterial infections as a result of the development of resistance to antibiotics has in recent time remained a serious problem confronting public health. This study investigated the antibiogram of Staphylococcal isolates and molecular characterisation of Coagulase Negative Staphylococci (CoNS) obtained from female patients visiting Rivers State University Teaching Hospital (RSUTH) in Port Harcourt, Nigeria. A total of 103 clinical samples were collected and processed using the standard laboratory procedures. Antibiotic susceptibility test of the isolates was performed using Kirby-Bauer disc diffusion method, following Clinical and Laboratory Standards Institute (CLSI) guidelines. Molecular characterisation as well as screening for the detection of antibiotics resistance MecA gene was carried out using Polymerase Chain Reaction (PCR) dependent molecular techniques. From the study, 22.3% S. aureus and 1.9% CoNS were recovered. The 16SrRNA gene sequencing revealed two species of CoNS namely S. saprophyticus and S. arlettae. The antibiotics susceptibility test results revealed that all the Staphylococcus aureus isolates were 100% resistant to six of the antibiotics tested: Ampicillin, Augmentin, Ceftazidime, Cefuroxime and Cephalexin (β- lactams), 78.3% resistant to Tetracycline and Cotrimoxazole, 73.9% to Vancomycin, 65.2% to Ciprofloxacin, 56.5% to Gentamicin and 47.8% to Erythromycin but 52.2% sensitive to Erythromycin, followed by Gentamicin (34.8%), Ciprofloxacin (17.4%), Vancomycin and Cotrimoxazole (13%) and Tetracycline (8.7%). All (100%) of the Coagulase negative Staphylococci species were resistant to every antibiotics tested. Data obtained from the study showed all the isolates displayed multidrug resistance, with MAR indices greater than 0.2 and Methicillin (MecA) gene was detected in 66.6% of the isolates. The study has reported the presence of Coagulase Negative Staphylococci showing resistance to all the tested antibiotics, hence indicating alarming public health threats. Strict regulation of antimicrobial usage is therefore vital.