Disinfectant resistance in multiple antibiotic resistant bacteria isolated from clinical cases in animals

The aim of this study was to investigate the presence of disinfectant resistance genes, including qacA/B, qacC/D, qacE, qacΔE1, qacG, qacH, qacJ, and acrA, in bacteria exhibiting multiple antibiotic resistance (MDR) isolated from clinical cases using the PCR method. For this purpose, a total of 44 bacterial isolates were examined, comprising 10 Staphylococcus aureus, 22 Escherichia coli, 6 Pseudomonas aeruginosa, 3 Klebsiella pneumoniae, and one isolate each of Salmonella Kentucky, Salmonella Typhimurium, and Salmonella Infantis. Antibiotic susceptibilities of these bacterial isolates were determined using commercially available antibiotic-impregnated paper discs containing Penicillin (P, 10 UI), Imipenem (IMP, 10 μg), Marbofloxacin (MAR, 5 μg), Ampicillin (AM, 10 μg), Oxytetracycline (T, 30 μg), Erythromycin (E, 15 μg), Spiramycin (SP, 100 μg), Enrofloxacin (ENR, 5 μg), Gentamicin (CN, 10 μg), Tylosin (TY, 15 μg), Amoxicillin/Clavulanic Acid (AMC, 20/10, 30 μg), Ceftriaxone (CRO, 30 μg), Streptomycin (S, 10 μg), and Trimethoprim/ Sulfamethoxazole (SXT, 1.25/23.75, 25 μg). For the detection of disinfectant resistance genes, two multiplex PCR assays were conducted. The first group targeted qacG (275 bp), qacJ (306 bp), qacE (350 bp), and acrA (567 bp), while the second group focused on qacC/D (249 bp), qacH (295 bp), qacΔE (335 bp), and qacA/B (629 bp). Minimum inhibitory concentration (MIC) values were determined for isolates harboring resistance genes using commercially available preparations containing benzalkonium chloride and chlorhexidine gluconate. Among the 22 E. coli isolates, two exhibited resistance to 5 antibiotics, three to 6, four to 7, one to 8, one to 9, eight to 10, two to 11, and one to 13 different antibiotics. Of the 6 P. aeruginosa isolates, one was resistant to 3 antibiotics, two to 4, two to 7, and one to 8. Among the 3 K. pneumoniae isolates, two were resistant to 7 antibiotics and one to 12. S. Kentucky exhibited resistance to 5 antibiotics, while S. Typhimurium and S. Infantis were each resistant to 7 antibiotics. Among the S. aureus isolates, one exhibited resistance to 5 antibiotics, one to 6, six to 7, and two to 12 antibiotics. Overall, antibiotic resistance rates ranged from 0% to 100%. Multiplex PCR results showed that qacG (275 bp), qacJ (306 bp), qacE (350 bp), acrA (567 bp), qacC/D (249 bp), and qacH (295 bp) genes were negative in all isolates. However, in E. coli strains, the qacΔE (335 bp) gene was detected in 7 isolates, while the qacA/B (629 bp) gene was present in 13 isolates. All 7 isolates positive for qacΔE (335 bp) also harbored the qacA/B (629 bp) gene, whereas the remaining 6 isolates contained only the qacA/B (629 bp) gene. MIC values for isolates harboring resistance genes ranged from 32 to 128 mg/L for benzalkonium chloride and from 2 to 32 mg/L for chlorhexidine gluconate. In conclusion, investigating biocide/disinfectant resistance and its potential association with cross-antibiotic resistance is crucial within the One Health framework. Therefore, while raising awareness about antibiotic resistance, the importance of disinfectant resistance should not be overlooked.