Characterization of secondary bacterial infections in Buruli ulcer disease in Ghana: a focus on antimicrobial resistant Staphylococcus aureus

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BACKGROUND: Buruli ulcer (BU), caused by Mycobacterium ulcerans, is a chronic necrotizing skin disease often complicated by secondary bacterial infections that may delay healing and worsen clinical outcomes. Among these, Staphylococcus aureus is frequently implicated; however, the broader spectrum of bacterial colonizers and their antimicrobial resistance patterns in BU lesions remain inadequately characterized. This study aimed to characterize secondary bacterial infections in BU lesions, with a particular focus on the frequency, antimicrobial resistance profile, and methicillin resistance determinants of S. aureus. METHODS: From October 2023 to March 2025, wound swabs were collected from PCR-confirmed BU patients across three endemic districts in Ghana before the start of BU-specific antibiotic treatment. Bacterial isolates were cultured and identified using standard microbiological techniques and the BioMérieux VITEK 2 compact system. Antimicrobial susceptibility testing was interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Molecular detection of the mecA gene was performed using conventional polymerase chain reaction (PCR) with agarose gel electrophoresis confirmation. RESULTS: A total of 83 bacterial isolates representing 18 genera were recovered from 31 of 40 BU patients. Gram-positive bacteria accounted for 56.6% (47/83) of isolates, while Gram-negative organisms constituted 43.4% (36/83). Staphylococcus aureus was the predominant species (17/83; 20.4%). The isolates exhibited high resistance to benzylpenicillin (94%) and tetracycline (82%), but retained complete susceptibility (100%) to linezolid, moxifloxacin, and quinupristin/dalfopristin. The mecA gene was detected in 94.1% of S. aureus isolates, indicating a high prevalence of methicillin-resistant S. aureus (MRSA). Notably, PCR-based detection identified a higher proportion of MRSA compared with phenotypic methods (94.1% vs. 58.8%). CONCLUSION: Secondary bacterial infections in BU lesions are microbiologically diverse, with S. aureus emerging as a predominant and clinically significant pathogen. The high prevalence of MRSA highlights the need for integrated management strategies addressing both M. ulcerans and co-infecting bacteria. Furthermore, reliance on phenotypic methods alone may underestimate MRSA burden, underscoring the importance of incorporating molecular diagnostics into routine surveillance and clinical care in endemic settings. CLINICAL TRIAL NUMBER: Not applicable.

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