Correlation between antibiotic resistance and phylogenetic types among multidrug-resistant Escherichia coli isolated from urinary tract infections

OBJECTIVE(S): Emergence of multidrug resistance has reduced the choice of antimicrobial regimens for UTIs. To understand the association of phenotype and genotype among uropathogens. MATERIALS AND METHODS: Six hundred and twenty-eight (628) urine samples were collected and analyzed. Antibiotic sensitivity pattern was determined by the Kirby-Bauer Disc Diffusion Method and minimum inhibitory concentration (MIC) was tested by the E test. Fluoroquinolone resistant mutations in QRDR of gyrA and ParC, phylogenetic groups, and PAIusp subtype were detected by PCR. RESULTS: Most prevalent uropathogens were Escherichia coli (53.2%) followed by Klebsiella pneumoniae (21%). Multidrug- resistance was observed in > 50% cases for third-generation cephalosporins and ciprofloxacin and lowest in meropenem. E. coli (66.2%) and K. pneumonia (64.4%) were extended-spectrum β-lactamases (ESBLs) producers. MIC to trimethoprim-sulfamethoxazole was highest in E. coli (>1024 µg/ml). In 80 (24%) of the 334 E. coli isolates analyzed in detail, 54 fluoroquinolones (FQ) resistant isolates carried mutations (S83L, D87N, S80I, E84V) in QRDR of gyrA and ParC. Out of 54 FQ-resistant isolates, 43 (79.6%) isolates belonged to the phylogenetic group B2, and 11(20.4%) belonged to group D. Isolates belonged to group B2, 38 (88.4%) of the 43 isolates carried PAIusp subtype IIa and high frequency of mutation E84V in ParC was detected in 37 (97.4%). Other mutations, such as S80I, S83L in gyrA and D87N in ParC were found in all resistant isolates. CONCLUSION: Correlations between phenotype and genotype provided a basis to understand the resistance development in uropathogens, and PAIusp subtyping indicated that E. coli belonged to the B2 group.