Chronic wounds in Sierra Leone: pathogen spectrum and antimicrobial susceptibility

Chronic wounds are frequently caused by, or super-infected with, a broad spectrum of bacteria. To guide treatment, healthcare providers need to know the bacterial spectrum and antimicrobial resistance rates to be anticipated. As these data are largely missing for Sierra Leone, we performed a microbiological study on chronic wound infections.

Wound swabs were analysed for bacteria using culture-based methods. Antimicrobial susceptibility testing was done with Vitek2® automated system and EUCAST clinical breakpoints. Selected resistance phenotypes were confirmed by molecular methods (e.g. mecA/C) and genotyping.

Of 163 included patients, 156 (95.7%) had a positive wound culture. Pseudomonas aeruginosa (n = 75), Klebsiella pneumoniae (n = 42), Proteus mirabilis (n = 31), Staphylococcus aureus-related complex (n = 31) were predominant. Among Gram-negative rods, resistance rates were high for piperacillin/tazobactam (3-67%), cefotaxime (19-71%), and ciprofloxacin (13-60%). Among isolates of the S. aureus-related complex, 55% were methicillin resistant (CC8, PVL-negative).

The high antimicrobial resistance rates in bacteria from chronic wounds strongly speaks against the use of empirical systemic antibiotic therapy if patients do not show signs of systemic infections, and supports the strategy of local wound care.