Molecular characterization of antimicrobial resistance and virulence factors in coagulase – negative staphylococci nasal isolates among adult patients in a tertiary hospital in North-Western Nigeria

Abstract

Coagulase-negative staphylococci are harmless microorganisms that can become pathogenic when the host resistance is impaired. Their ability to exhibit multidrug-resistance and form biofilm limit treatment options and contributes to the health and financial burden on health care systems worldwide. This study aimed to provide data on the acquisition and expression of genetic elements associated with resistance and virulence in the organisms from nasal colonization of adults admitted to a University Teaching Hospital in Nigeria. One hundred and twenty-three presumptive staphylococci isolates were obtained from the medical microbiology laboratory of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria. The isolates were characterized, and the antibiotics susceptibility pattern assessed. Biofilm formation was evaluated by the micro-titre plate method, and polymerase chain reaction was used to detect resistance genes (mecA and ermB), virulence gene (psm-mec) and adhesin genes, (icaAB, icaC and icaD) in the isolates.

Out of the 60 coagulase-negative staphylococci isolates, 50 (83.3%) were strong biofilm formers, 5 (8.3%) were moderate biofilm formers and 5 (8.3%) were weak biofilm formers. For the 14 isolates that were characterized by PCR, mecA and ermB resistance genes were detected in 78% and 71% of the isolates respectively. Twenty-one percent had psm-mec virulence gene while biofilm adhesin genes, icaAB and icaD were detected in 36% and 57% respectively, icaC gene was not detected.

This study confirmed formation of biofilm, carriage of resistance and virulence genes which have been shown to play a role in pathogenesis. This study shows the necessity of the periodical monitoring of the drug resistance pattern and virulence factors of coagulase-negative staphylococci.