Antibiotic susceptibility of wound swab isolates in a tertiary hospital in Southwest Nigeria

Background: Wounds are commonly encountered in the clinical practice. Microbacterial colonization and infection negatively affect wound outcomes. With increasing emergence of antibiotic-resistant strains, it is essential to determine local patterns of wound microbiological profile and antibiotic susceptibility to guide rational empirical antibiotic use. Materials and Methods: Consecutive patients who presented to the plastic surgery unit were recruited to the study over a 6-month period. Wound swab cultures were performed at presentation using standard protocols and media. The wound swab was performed by the Levine technique and data were analyzed using a statistical software package. Results: Eighty-five microbial isolates were obtained from the eighty patients (55 males and 25 females) recruited. Gram-positive isolates were 35 (41.2%) and Gram-negative were 50 (58.8%). There was equal distribution of acute and chronic wounds. Pseudomonas aeruginosa was the most common isolate at 30.6%, followed by Staphylococcus aureus (27.1%), Escherichia coli (9.4%), Streptococcus species (8.2%), and Morganella morganii (7.1%). The isolates demonstrated resistance to amoxicillin-clavulanate, ampicillin, cloxacillin, cefuroxime, ceftazidime; low-to-moderate sensitivity to erythromycin, gentamicin, streptomycin, tetracycline, ciprofloxacin, and ofloxacin; and a moderate sensitivity to ceftriaxone and a high sensitivity to imipenem. There was significant difference in antibiotic resistance patterns between Gram-positive isolates from acute and chronic wound infections but not for acute and chronic wound Gram-negative isolates. Conclusion: Most of the microbial isolates, particularly the Gram-negative isolates demonstrated low sensitivity to commonly used antibiotics and moderate-to-high sensitivity to less commonly used newer antibiotics.