Bacterial Aetiology and Antibiotic Susceptibility Profile of Post-Operative Sepsis among Surgical Patients in a Tertiary Hospital in Rural Eastern Uganda

Background: Post-operative wound sepsis remains a surgical challenge of public health concern constituting approximately 20% of the health care-associated nosocomial infections. This study aimed at determining the prevalence and antimicrobial resistance patterns of bacterial pathogens isolated from post-operative wound infections at Mbale Regional Referral Hospital.

Materials and Methods: This was a descriptive cross-sectional study conducted from June to October 2015. Study participant samples were sub-cultured upon reception in the Microbiology laboratory and the isolated bacterial pathogens were analysed. Phenotypic antimicrobial susceptibility profiles were determined using the Kirby-Bauer method. Interpretation of the zone diameters was done following the Clinical and Laboratory Standards Institute guidelines. Phenotypic screening for Methicillin-resistant Staphylococcus aureus (MRSA) was performed using oxacillin (1 µg). D-test was also performed for phenotypic screening of inducible clindamycin resistant Staphylococcus aureus. Data were entered into Microsoft Excel and analysed using IBM SPSS statistics (version 16).

Results: Overall post-operative sepsis was 69/80 (86.2%) with Staphylococcus aureus as the most predominant organism 41/104 (39.4%) followed by Escherichia coli 22/104 (21.2%) and Klebsiella species 15/104 (14.4%). Of the 41/104 isolated Staphylococcus aureus, 27/41(65.9%) were MRSA strains and 5/41 (12.2%) were inducible clindamycin resistant Staphylococcus aureus strains. The isolated Staphylococcus aureus was resistant to multiple drugs though susceptible to vancomycin and clindamycin. In addition, none of the isolated Enterococci species was vancomycin resistant. Although most of the isolated Gram-negative organisms were sensitive to imipenem, resistance was observed for tetracycline, trimethoprim/sulphamethoxazole, and ceftriaxone.

Conclusion: Staphylococcus aureus was the most common causative agent associated with post-operative sepsis with most of the strains being MRSA. Multi-drug resistance was observed in 63/104 (60.6%) of the isolated organisms in our study. Hence the need to better develop and strengthen antimicrobial stewardship programs as well as to understand the carriage of antimicrobial resistance genes among these organisms.