# Antibiogram and molecular characterization of extended-spectrum β-lactamase-producing pathogens implicated in chronic suppurative otitis media

## TL;DR

This study examines antibiotic-resistant bacteria in chronic ear infections, finding that ESBL-producing pathogens are common and often resistant to multiple drugs.

## Contribution

The study provides new insights into the prevalence and molecular characteristics of ESBL-producing bacteria in chronic suppurative otitis media.

## Key findings

- ESBL-producing GNB pathogens were found in 18.3% of CSOM patients.
- blaSHV was the most common ESBL gene detected in isolates.
- Isolates showed high resistance but remained susceptible to ciprofloxacin, imipenem, and amikacin.

## Abstract

beta-lactamase-producing bacteria, especially extended-spectrum beta-lactamase (ESBL) producers have strong clinical relevance and have been implicated in chronic suppurative otitis media (CSOM) treatment failures. This study aimed to determine the frequency, antibiogram, and molecular characteristics of ESBL-producing gram-negative bacterial (GNB) pathogens isolated from patients with CSOM.

three hundred (300) ear swab samples collected from patients with active CSOM were analysed using standard microbiological techniques. Antibiogram of pathogens was determined by Kirby-Bauer disk diffusion technique. Phenotypic detection and molecular characterization of ESBL-producing GNB pathogens were performed by double disk synergy test (DDST) and polymerase chain reaction (PCR).

Escherichia coli and P. aeruginosa were more prevalent among CSOM patients with a duration of discharge >2 weeks. The frequency of ESBL producers among the GNB pathogens was 18.3%. Isolates were generally multidrug-resistant but very susceptible (100% - 70.4%) to ciprofloxacin, imipenem, and amikacin. Multiple antibiotic resistance values of the isolates ranged from 0.7-0.8. Polymerase chain reaction showed that blaSHV (47.6%) was the most predominant ESBL genotype. This was followed by blaTEM (25.2%) and blaCTX-M (10.7%) as the least predominant ESBL gene. Concomitant expression of ESBL gene was observed in 13.6% of the isolates.

this study reported the occurrence and spread of β-lactamase-producing bacteria in patients with CSOM infections. It is therefore very crucial to screen for antibiotic-resistant pathogens at early stages of CSOM infections, for proper antimicrobial therapy and to curb the increasing spread of antimicrobial resistance.