Antibiotic susceptibility profiles and detection of genes mediating extended-spectrum β-lactamase (Esbl) production in escherichia coli isolates from National Hospital, Abuja

Abstract

Background: Extended-spectrum beta-lactamases (ESBL) are the most widespread of the new beta-lactamases and are a significant threat to patient care in the hospital and the community. Aim: The study assessed the prevalence, antibiotic susceptibility profile, and major ESBL encoding genes among Escherichia coli isolated from clinical specimens of patients in the National Hospital, Abuja (NHA).

Materials and methods: E. coli isolated from diverse clinical specimens obtained from clinically proven cases of infection managed at the NHA were included in the study. The antimicrobial susceptibility was performed by the Kirby-Bauer method and E-test was used to confirm the ESBL phenotype. Multiplex polymerase chain reaction (PCR) was used to detect the genes mediating ESBL production.

Results: Meropenem, fosfomycin, and tigecycline demonstrated excellent activities against all isolates: of the 400 isolates, 392 (98%), 386 (96.5%), and 362 (90.5%) were susceptible, respectively. Similarly, 358 (89.5%) were susceptible to amikacin, 323 (80.3%) nitrofurantoin, 281 (70.3%) ceftazidime, and 279 (69.8%) cefotaxime. A total of 271 (67.8%), 219 (54.8%), and 208 (52.0%) were resistant to amoxicillin-clavulanate, ciprofloxacillin, and gentamicin, respectively. However, all the isolates were resistant to ampicillin. There was a significantly higher proportion of multidrug resistance among ESBL-producing isolates compared to non-ESBL-producing isolates (P = 0.0001). Of the 121 phenotypically detected ESBL isolates, 119 (98.3%) harbored genes mediating the production of Cefotaximase- Munich (CTX-M), Temoniera (TEM) or Sulfhydryl Variable (SHV) enzymes.

Conclusion: The prevalence of ESBLs among E. coli was relatively high, at 30.2%. About 81% of all blood isolates were ESBL-producers. bla_CTX-M is the predominant type of ESBL gene among E. coli. A high proportion of the ESBL-producing isolates expressed a combination of two or three genes together.

Keywords: Antibiotic resistance; ESBL; Escherichia coli.