Identification and Antibiotic Resistance Profile of Biofilm-forming Methicillin Resistant Staphylococcus aureus (MRSA) Causing Infection among Orthopedic Wound Patients

Background and Objectives: The biofilm-forming ability of Methicillin-Resistant Staphylococcus aureus(MRSA) strains have demonstrated the involvement of MRSA biofilm in antibiotic resistance, recalcitrant and persistent infections in humans. Despite a deeper understanding of the biofilm-forming ability of MRSAstrain, it is still essential to extend the research on the identification and antibiotic resistance profile of biofilm-forming MRSA causing infection among orthopedic wound patients.

Methodology: A total of three hundred and thirty (303) patient-isolate of non-repeatable Staphylococcus aureus strains were obtained during the period of 2021 until 2022 from fracture and post-surgical orthopedic wound patients with wound duration >2months at the National Orthopedic Hospital, Enugu (NOHE). S. aureus were identified using conventional microbiological cultures Technique followed by confirmation of MRSA strain through Brilliance MRSA 2 Agar. Antibiotic Susceptibility testing (AST) of biofilm-forming MRSA was performed using the Kirby–Bauer disk diffusion method and the results were interpreted using the Clinical Laboratory Standard Institute (CLSI) zone diameter breakpoints. Multidrug Resistance (MDR) was determined for biofilm-forming MRSA.

Result:Of the 303 isolate of S. aureus, MRSA strain accounted 86(28.4 %) and 78(25.7 %) from post-surgical wound and fracture wound respectively while biofilm forming MRSA was identified in 101(33.4%) MRSA strain consisting of high proportion 66(21.8 %) fromPost-surgical wound followed by fracture wound samples recording 35(11.6 %). Association between MRSA production and biofilm formation was considered statistically significant at P< .05. The proportion of biofilm-forming MRSA resistance to β-lactam accounted 71.4-100%, macrolide resistance recorded 65.7-92.4 %, lincosamideresistance 74.3-100 %, glycopeptide resistance proportion ranged from 62.8-100 % while low level of resistance to fluoroquinolones 19.7-42.9 % and Aminoglycoside 8.6-10.6 % was observed. Biofilm-forming MRSA isolate were MDR to one or more antibiotic antimicrobial agents in at least three categories withMDRIndex range ≥ 0.3 but majority of the isolate were 91.4% and 100% susceptible to Gentamicin and Imipenem.

Conclusion: The invitro expression of biofilm formation among MRSA strain and their antibiotic resistance profile in this study makes them a potential threat and challenging pathogens with the ability to cause persistent infections in humans, especially among orthopedic wound patients. Thus the development of an antimicrobial stewardship program and regular detection of biofilm production is needed for timely intervention while judicious use of Imipenem and Gentamicin as a drug of choice for effective treatment of infection caused by biofilm-forming MRSA among orthopedic patients will avert the severity of infection. Further research of these sort should investigate the genotyping expression of a biofilm gene variant in other human diseases, different bacteria species, and orthopedic medical implant devices.