Distinct microbial species in acute and chronic wounds in community-recruited injection drug users: Antimicrobial sensitivity more common than not
Methods: Acute (duration <8 weeks) and chronic wounds (duration ≥8 weeks) in clients of the BNEP were cleaned and debrided prior to sampling for aerobic and anaerobic culture. Cultures were processed using standard microbiologic procedures for aerobes and anaerobes, and routine antimicrobial sensitivity testing was performed. Statistical analysis included t-tests and logistic regression.
Results: Fifty wounds from 35 participants were cultured. Of these, 52% were chronic wounds and 48% were acute wounds. Rates of methicillin-sensitive Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) were equivalent, 36%. Pseudomonas aeruginosa was the most common gram-negative organism overall and was present in chronic wounds exclusively (27%). P. aeruginosa isolates were highly antibiotic-sensitive with only one isolate showing resistance to piperacillin. Escherichia coli was the second most common gram-negative organism (12%), and isolates were also highly antibiotic sensitive. Four of six E. coli isolates were resistant to only ampicillin and trimethoprim/sulfamethoxazole (67%), and two of six isolates were pan-sensitive (33%). Chronic wounds were more common in African Americans (OR 4.25, 95% CI 1.25–14.50), and more often had anaerobic bacteria (OR 4.38, 95% CI 1.03–18.56). Women had greater risk of MRSA-positive cultures (OR 6.50, 95% CI 1.38–30.68). MRSA was not seen preferentially in one wound type versus the other.
Conclusion: Highly antibiotic-sensitive gram-negative bacteria were seen in this population, suggesting that this community-based sample of individuals may have limited historical interactions with the health care system. There are also differences in cultivatable wound microbiome by race, gender and wound type among IDUs that warrant additional investigation. The potential implications of these differences regarding microbial wound communities may inform treatment and prevention efforts.
M. E. Smith,
C. P. Chaulk, None
K. Johnson, None