PP 12 - Microbiological profile and antibiotic susceptibility patterns in wound infections: A comparative analysis in a base hospital settingase hospital setting

Ranasinghe RATK¹, Adikari AMDR², Sandamali RMI²  ,  ¹University of Sri Jayewardenepura, ²Colombo East Base Hospital

Abstract

Introduction

Wound cultures are essential for guiding targeted antimicrobial therapy in wound infections. Accurate identification of the pathogens depends on the type and quality of the specimen submitted for microbiological analysis.

Objectives

To describe the spectrum of bacterial pathogens isolated from different types of wound specimens and to evaluate their antibiotic susceptibility patterns.

 Design, setting, and methods

During this observational study, wound culture samples received by the microbiology laboratory in a base hospital over three months were cultured on standard media. Pathogens were identified using biochemical methods, and antibiotic susceptibility testing was performed.

Results

A total of 195 samples were analysed, comprising 29 pus samples, 84 wound tissue samples, 80 wound swabs, and two bone samples.  Of these, 60.5% (118/195) yielded positive cultures. Both bone samples were culture-positive (100% yield). From the rest of the samples, culture positivity rate was highest in wound tissue samples at 70.2% (59/84), followed by wound swabs at 53.8% (43/80) and pus samples at 48.3% (14/29).

The predominant organisms isolated were coliforms (71.8%, n=97), followed by Pseudomonas spp. (19.3%, n=26), Staphylococcus aureus (7.4%, n=10), and Streptococcus spp. (1.5%, n=2). Among coliforms, 53.6% showed resistance to cefotaxime and ceftriaxone. Resistance to ceftazidime was observed in 26.9% of Pseudomonas isolates. Notably, 70% (n=7) of Staphylococcus aureus isolates were methicillin-resistant (MRSA). Two Streptococcus isolates were susceptible to penicillin.

Conclusion

Bone and wound tissue samples demonstrated higher culture positivity compared to swabs, indicating their superiority in detecting the true pathogens. The predominant isolation of coliforms and Pseudomonas spp. warrants correlation with clinical findings to determine their clinical significance. Knowledge of the local microbiological profile demonstrated in this study may help optimise wound management, guide effective empiric antibiotic therapy, and support antimicrobial stewardship practices.