Antimicrobial Resistance Patterns and Prevalence of tetA/tetB Genes in Uropathogenic Escherichia coli Isolated from Urinary Tract Infections in Swat, Pakistan: Original Article

Aftab Ali; Sadaf Anwar Qureshi; Aamir Sohail; Dildar Khan; Muhammad Salahuddin; Sofia Bano

doi:10.69837/pjammr.v4i2.135

Authors

Aftab Ali PhD Scholar, Institute of Pathology and Diagnostic Medicine, Khyber Medical University, Peshawar, Pakistan
Sadaf Anwar Qureshi Assistant Professor, Department of Pathology, Ayub Medical College, Abbottabad, Pakistan
Aamir Sohail PhD Scholar, Department of Microbiology, University of Haripur, Haripur
Dildar Khan M Microbiologist, Public Health Reference Laboratory, Khyber Medical University, Peshawar, Pakistan
Muhammad Salahuddin B5. Microbiology Student, Institute of Pathology and Diagnostic Medicine, Khyber Medical University, Peshawar, Pakistan
Sofia Bano BS Microbiology Student, Institute of Pathology and Diagnostic Medicine, Khyber Medical University, Peshawar, Pakistan

DOI:

https://doi.org/10.69837/pjammr.v4i2.135

Keywords:

Urinary tract infection; Uropathogenic Escherichia coli; Antibiotic Resistance; Tetracycline resistance genes; tetA and tetB genes

Abstract

Objective: To characterize uropathogenic Escherichia coli isolated from urinary tract infections in non-hospitalized patients in Swat, Pakistan, by assessing demographic distribution, antimicrobial susceptibility patterns, and the prevalence of tetracycline resistance genes (tetA and tetB).

Methods: We collected 250 midstream urine samples from outpatients with suspected UTI at a tertiary care hospital in Swat, Khyber Pakhtunkhwa, Pakistan. Samples were cultured on Cystine Lactose Electrolyte-Deficient (CLED) and MacConkey agar, and isolates meeting the threshold for significant bacteriuria (≥10⁵ CFU/mL) were identified using Gram staining and standard biochemical tests (indole, urease, lactose fermentation), with identification confirmed by PCR targeting the 16S rRNA gene. We determined antibiotic susceptibility of confirmed isolates by the Kirby-Bauer disk diffusion method on Mueller-Hinton agar and interpreted results according to CLSI M100 (35th edition, 2025) breakpoints for Enterobacterales. PCR subsequently screened isolates phenotypically resistant to tetracycline for the tetA and tetB resistance genes.

Results: Of the 250 samples screened, 150 (60.0%) were presumptively identified as E. coli, of which 145 (58%) were confirmed by 16S rRNA PCR. Women accounted for the substantial majority of confirmed isolates (80.7%, 117/145), with infections concentrated in the 20–30-year age group, whereas male isolates peaked later, in the 60–70-year group. Resistance was highest against ampicillin (97.2%), cefixime (87.6%), ciprofloxacin (56.6%), and tetracycline (55.2%), while piperacillin-tazobactam (2.1%), amikacin (4.1%), fosfomycin (4.8%), imipenem 6.9%, and meropenem 13.1% retained the greatest in vitro activity. Among the 80 phenotypically tetracycline-resistant isolates, tetA was detected more frequently (61.3%, 49/80) than tetB (45.0%, 36/80).

Conclusion: UPEC isolates in this study showed extensive resistance to first-line agents, including ampicillin, cefixime, and fluoroquinolones, while carbapenems, fosfomycin, and piperacillin-tazobactam remained largely reliable. The predominance of tetA over tetB adds region-specific molecular detail to the local tetracycline resistance landscape. These findings support revising empirical prescribing guidance in this setting and reinforce the need for robust antimicrobial stewardship, ongoing resistance surveillance, and safe antibiotic use