Antibiotic resistance in uropathogenic Escherichia coli strains at Brazzaville University Hospital, Congo and the therapeutic consequences

Background: Urinary tract infections (UTIs) are a very frequent reason for consultations and antibiotic prescriptions in everyday practice. Excessive and inappropriate use of antibiotics is responsible for the emergence and spread of multidrug-resistant (MDR) uropathogenic bacteria. The aim of this study was to determine the frequency of isolation and antibiotic resistance of uropathogenic strains of Escherichia coli (UPEC) isolated in the bacteriology-virology laboratory of the University Hospital Centre (CHU) in Brazzaville, Congo. Methodology: This was a descriptive retrospective study over a 6-month period (from 1 April to 31 September 2022) that included all non-redundant uropathogenic UPEC strains isolated from urine samples of patients with UTIs referred to the bacteriology-virology laboratory of the University Hospital of Brazzaville, Congo. The strains were isolated from urine samples after inoculation onto Cystine Lactose Electrolyte Deficient agar (CLED), and incubating aerobically at 37°C for 24 hours. Identification was carried out using BioMérieux API 20 E galleries and antibiotic susceptibility testing was performed on Mueller Hinton agar medium using selected antibiotic discs. Extended spectrum β-lactamase (ESBL) production by the isolates was confirmed by double disc synergy test. Data were analysed using Microsoft Office Excel 2013. Results: Of the 187 non-repetitive uropathogenic Enterobacteriaceae isolated from urine samples of 187 patients with clinical UTIs, 81 were strains of UPEC, giving an overall frequency of UPEC isolation of 43.0%. The modal age of patients from whom UPEC strains were isolated was 57 years (age range 2 to 86 years), with 49 from females and 32 from males (F: M ratio of 1.5). The UPEC strains showed high rates of resistance to amoxicillin (94.0%), amoxicillin-clavulanic acid (84.0%), piperacillin-tazobactam (73.0%), ceftriaxone (52.0%), cefixime (54.0%), cefotaxime (55.0%), ceftazidime (58.0%), gentamicin (42.0%), ciprofloxacin (55.0%) and sulfamethoxazole-trimethoprim (90.0%) but relatively low resistance rates were observed with imipenem (4.0%), fosfomycin (8.0%) and amikacin (18.0%). The ESBL-producing strains accounted for 24.5% (46/187) of all uropathogenic Enterobacteriaceae isolates, and compared to the non-ESBL producing strains, had significantly higher resistance rates to gentamicin (p=0.018), ciprofloxacin (p=0.0003), ceftazidime (p<0.0001), ceftriaxone (p<0.0001), cefixime (p<0.0001), cefotaxime (p<0.0001), piperacillin-tazobactam (p=0.0006), and amoxicillin-clavulanate (p=0.0024). Conclusion: Our results show high rates of in vitro resistance of UPEC strains to commonly used antibiotics, which potentially limits therapeutic options and therefore a real public health challenge in Congo.