Multiple antibiotic resistance indexing and molecular identification of Escherichia coli isolated from clinical and nonclinical sources in Port Harcourt Metropolis, Nigeria

Otis Isaiah, Doubra; Otokunefor, Kome; Agbagwa, Obakpororo

Multiple antibiotic resistance indexing and molecular identification of Escherichia coli isolated from clinical and nonclinical sources in Port Harcourt Metropolis, Nigeria

Otis Isaiah, Doubra, Otokunefor, Kome and Agbagwa, Obakpororo ORCID: https://orcid.org/0000-0003-2063-621X (2025) Multiple antibiotic resistance indexing and molecular identification of Escherichia coli isolated from clinical and nonclinical sources in Port Harcourt Metropolis, Nigeria. Pan African Medical Journal, 51 (11).

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Official URL: http://dx.doi.org/10.11604/pamj.2025.51.11.38524

Abstract

Introduction: the emergence of antibiotic resistance in E. coli strains has led to a variety of clinical illnesses in both humans and animals, with consequences for human health and the environment.

Methods: this cross-sectional study was conducted to determine the risk of increased antibiotic resistance by calculating the multiple antibiotic resistance (MAR) index of E. coli in Port Harcourt, Rivers State, Nigeria. A higher MAR index close to 1 was interpreted as having a higher level of antibiotic resistance, while a lower MAR index close to 0 is an indicative of little to no resistance. In this study, a total of 200 samples from clinical (urine and stool) and non-clinical sources (soil and poultry) were randomly collected following ethical approval. Escherichia coli was isolated on Eosin Methylene Blue agar and identified using standard biochemical tests. The antimicrobial susceptibility profile was determined using the disk diffusion methodology with Mueller-Hinton agar according to the instructions of the Clinical and Laboratory Standards Institute (CLSI). Escherichia coli isolates were amplified in this investigation using a 16s rRNA gene-based polymerase chain reaction (PCR) technique.

Results: for both 73% clinical (n=100) and 35% non-clinical (n=100) isolates, amoxicillin/clavulanic acid showed the highest rate of resistance with 82.2% (60 of 73) and 100% (35 of 35) respectively, whereas nitrofurantoin showed the lowest rate of resistance at 1.4% (1 of 73) clinical and no resistance was found for the nonclinical E. coli isolates. The study presumptively finds a higher resistance to 4 drug classes, with 42%, and the lowest of 1% to 6 drug classes of antibiotics. Additionally, MAR indices > 0.2 were observed in this study, which indicates excessive use of antibiotics. MAR index of 0.4 was the most frequent, with a 25% prevalence. The results of this investigation show that a MAR index of 0.4 suggests widespread antibiotic resistance, with 25% of the bacterial isolates from both sources exhibiting resistance to the tested antibiotics. A MAR index > 0.2 in this study indicates that 14.8% of the E. coli isolates were ineffective against the tested antibiotics. The bacteria isolates in this study have developed resistance to multiple antibiotics if the MAR index is greater than 0.2, which is an indication of overuse or inappropriate antibiotic use. The genotypic test verified 82.9% non-clinical E. coli (found in environmental soil and poultry samples) and 82.2% clinical E. coli (found in patient urine and stool samples). In this study, E. coli isolates were genotypically identified using the 16s rRNA gene.

Conclusion: the high levels of MAR indices in E. coli as presented in this study could be indicative of antibiotic treatment failures in both clinical and nonclinical settings, which can serve as a potential reservoir of drug-resistant E. coli that are harmful and therefore require continuous monitoring.