Antibiotic resistance profile of Staphylococcusaureus clinical isolates from Nigeria

Introduction

Hospital-acquired infections with Staphylococcus aureus have increased over the years and the rise in incidence has been accompanied by a rise in antibiotic-resistant strains notably methicillin-resistant S aureus (MRSA) and more recently vancomycin-resistant strains. In order to have adequate information for treatment of infections caused by S. aureus, it is important to understand trends in the antibiotic-resistance patterns as well as diversity of strains across geographical regions.

Objectives

The aim of this study was to provide information on the antibiotic resistance profile and molecular characteristics of S. aureus strains from Nigeria.

Methods

A total of 209 non-duplicate S. aureus isolates obtained from clinical infections in eight medical centres were analyzed. Identification and antimicrobial susceptibility profile was performed with the automated VITEK-2 system. Detection of antibiotic resistance and virulence genes in the S. aureus strains was by polymerase chain reaction.

Results

Resistance was observed against penicillin (97.1%); trimethoprim/sulfamethoxazole (83.7%), tetracycline (13.8%), levofloxacin (5.7%) and gentamicin(4.8%). All strains were susceptible to azithromycin, clarithromycin, erythromycin, clindamycin, linezolid, vancomycin, nitrofurantoin, fusidic acid, mupirocin and rifampicin. The β-lactamase (blaZ)gene was found in 95% of allstrains (n=198) while 2.87% (n=6) possessed the mecA gene. The staphylococcal cassette chromosome mec (SCC mec) typing of MRSA strains detected SCC mec type IV in one strain. A particular MRSA strain was the only strain found to be resistant to teicoplanin, tigecycline and fosfomycin. Fifty-six percent of the strains possessed the panton valentine leukocidin (PVL) encoding gene.

Conclusion

A rise in PVL-positive S. aureus strains in Africa is of great concern as this could promote the emergence of highly virulent strains. The continuous surveillance of antibiotic resistance in S. aureus is important to prevent the spread of multidrug resistant strains.

Disclosure of interest

None declared.