Antimicrobial resistance profiles of Enterobacteriaceae in Periplaneta americana from Dar es Salaam

Antimicrobial-resistant infections are rising globally, with synanthropic pests such as cockroaches facilitating spread through food and environmental contamination in urban low-resource settings. Despite their close association with human habitats, cockroaches remain an underestimated vector in AMR transmission. This study investigated the abundance and antibiotic resistance profiles of Enterobacteriaceae isolated from the gut of the domestic cockroach ( Periplaneta americana ) in Dar es Salaam, Tanzania. Ninety (90) P. americana specimens were collected from households and restaurants in selected areas of the city and transported aseptically to the University of Dar es Salaam microbiology laboratory for bacteriological isolation and antimicrobial susceptibility testing. Standard microbiological methods were used for bacterial isolation and identification, while antimicrobial susceptibility testing was performed using the Kirby–Bauer disk diffusion method. On other hand, resistance genes were detected using PCR amplification with gene-specific primers. A total of 123 Enterobacteriaceae isolates were recovered, comprising Klebsiella spp. (53%), Escherichia coli (30%), and Enterobacter spp. (17%). Overall, 69% of isolates exhibited phenotypic resistance to at least one antibiotic. Resistance was highest to amoxicillin (100%), ampicillin (98%), cephalexin (97%), erythromycin (96%), tetracycline (73%), chloramphenicol (67%), and trimethoprim–sulfamethoxazole (67%). Moderate resistance was observed for ciprofloxacin, azithromycin, and gentamicin (54% each), while lower resistance was noted for norfloxacin (40%) and ceftriaxone (29%). Resistance genes bla TEM, aac(3) -IV , catA1 and tet(A) were significantly associated with phenotypic resistance (χ² > 6.32, p < 0.043). The linkage between resistance genes and phenotypic resistance in cockroach-derived Enterobacteriaceae highlights synanthropic insects as key reservoirs of transferable AMR, supporting a One Health approach.