Antimicrobial Resistance Patterns of ESBL-Producing Escherichia coli in Dogs from Thailand: Evaluation of Algal Extracts as Novel Antimicrobial Agents.

Background/

Objectives

Multidrug-resistant (MDR) bacteria, including extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, in companion animals pose a growing public health concern due to the close interactions between pets and humans. This study aimed to investigate antimicrobial resistance patterns and the prevalence of ESBL-producing E. coli isolated from healthy dogs in Thailand, as well as the potential of algal extracts obtained through ethanol extraction and enzymatic hydrolysis as alternative antimicrobial agents against these drug-resistant organisms.

Methods

Antimicrobial susceptibility testing was performed on 43 E. coli isolates from healthy dogs. ESBL production was confirmed using standard phenotypic methods, and resistance genes were detected by PCR. The algal extracts were tested for antibacterial activity against MDR isolates.

Results

Among the 43 E. coli isolates, 67.44% were classified as MDR, with high resistance rates observed for ampicillin (79.07%), tetracycline (65.12%), and ciprofloxacin (62.79%), highlighting significant antimicrobial resistance concerns. Of the MDR isolates, 31.03% (9/29) were confirmed as ESBL producers. Gene analysis revealed blaTEM as the most prevalent gene (53.49%), followed by blaCTX-M (9.30%), while blaSHV was detected in a single isolate resistant only to ampicillin and was absent in all MDR strains. Ethanol extracts of Haematococcus pluvialis and Caulerpa lentillifera demonstrated inhibitory effects against MDR E. coli.

Conclusions

MDR and ESBL-producing E. coli are prevalent in healthy dogs, posing a potential public health risk. Algal extracts from H. pluvialis and C. lentillifera show promise as alternative antimicrobials. Further research is necessary to optimize their efficacy and investigate their in vivo applications, including clinical and environmental settings.