Abstract
BACKGROUND: The increasing prevalence of β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in community-acquired urinary tract infections (CA-UTIs) represents a growing public health challenge in low-resource settings. Data from Central Africa remain limited. This study investigated antimicrobial resistance profiles and phylogenetic diversity of these pathogens in southeastern Gabon. METHODS: Patients presenting with CA-UTIs were screened, and isolates of E. coli and K. pneumoniae were collected. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method and interpreted according to EUCAST 2024 guidelines. Phenotypic screening identified extended-spectrum β-lactamase (ESBL), AmpC, and carbapenemase production. Polymerase chain reaction (PCR) was used to detect ESBL genes (bla-CTX-M-gp1, bla-CTX-M-gp2, bla-CTX-M-gp9, bla-TEM, bla-SHV), plasmid-mediated AmpC genes (bla-CMY-1, bla-CMY-2, bla-ACT-1, bla-ACC, bla-FOX, bla-DHA), and the carbapenemase gene bla-OXA-48. Phylogenetic grouping of ESBL-producing E. coli was determined using PCR targeting chuA, yjaA, TspE4.C2, and arpA. RESULTS: Among 3,026 screened patients, 949 CA-UTIs were confirmed, including 589 cystitis and 360 pyelonephritis cases, yielding 200 isolates: E. coli (124) and K. pneumoniae (76). Of these, 68 (34.0%) were ESBL producers, 17 (9.0%) AmpC producers, and 2 (1.0%) carbapenemase producers. ESBL producing isolates were significantly associated with male sex (47.0%, p = 0.02) and children ≤5 years of age (48.2%, p = 0.007). ESBL- and AmpC-producing isolates exhibited high resistance rates (20-100%) to β-lactams, fluoroquinolones, and trimethoprim-sulfamethoxazole, while retaining susceptibility to carbapenems, ceftazidime-avibactam, and nitrofurantoin (up to 100%). Molecular analysis showed predominance of bla-CTX-M-gp1 in E. coli (40% alone; 31% in combination with bla-TEM). In K. pneumoniae, bla-SHV + bla-TEM (49%) and bla-SHV + bla-CTX-M-gp1 + bla-TEM (42%) were the most frequent gene combinations; one isolate carried bla-OXA-48. ESBL-producing E. coli predominantly belonged to phylogroup A (48.6%). CONCLUSION: Multidrug-resistant ESBL-, AmpC-, and OXA-48-producing E. coli and K. pneumoniae are circulating in community settings in southeastern Gabon. These findings underscore the need for strengthened antimicrobial resistance surveillance and evidence-based community-level interventions.