Biofilm Formation and Antibiotic Susceptibility Profile of Clinical Isolates of Staphylococcus aureus Isolated from Clinical Samples in Zaria, Nigeria

Background: Staphylococcus aureus is one of the common pathogens associated with nosocomial as well as community acquired infections due to its ability to form biofilms.

Research aim: The aim of this study was to observe the biofilm forming abilities and to study the antibiotic susceptibility profile of clinical isolates of S. aureus.

Methodology: A total of 56 isolates from clinical samples were identified using standard techniques and the isolates were further tested for biofilm formation, using microtiter plate assay and antibiotic susceptibility testing was carried out using Kirby-Bauer method.

Results: The results showed that out of the 56 S. aureus isolated, biofilm formation was observed in 27 (48.2%). Strong biofilm formation was observed in 5.4% (3) of the isolates, moderate biofilm formation in 8.9% (5) of the isolates, weak biofilm formation in 33.9% (19) of the isolates, while 51.8% (29) of the isolates were non-biofilm formers. Prevalence of S. aureus infection was higher in females (67.9%) compared to males (32.1%). The isolates were highly susceptible to Gentamicin (100%), Tigecycline (98.21%), Sulphamethoxazole-Trimethoprim (89.29%), Ciprofloxacin (89.29%) and Linezolide (75%), while the isolates showed low susceptibility to Erythromycin (28.55%), Clindamycin (35.71%) and Vancomycin (41.07%). None of the isolates showed inducible Clindamycin resistance phenotypically. 9 (16.67%) of the isolates showed constitutive phenotype, 3 (5.36%) showed Methicillin-Sensitive (MS) phenotype while 44 (78.57%) showed none of the above phenotypes.

Conclusion: Clinical isolates of S. aureus have the potential of producing biofilm and this could influence the rate of resistance.