The relationship between phylogenetic groups and antibiotic susceptibility patterns of Escherichia coli strains isolated from feces and urine of patients with acute or recurrent urinary tract infection

Abstract

Background and Objectives: B2 and D have been mentioned as the most common phylogenetic groups among uropatho- genic Escherichia coli. However, there is still controversy about the importance of these phylo-groups. This study was con- ducted to investigate the probable relation between these groups and antibiotic resistance patterns of E. coli isolates derived from urine and feces of the patients with acute or recurrent UTI.

Materials and Methods: 10 isolates were recovered from urine and feces samples of patients with different phases of UTI in whom E. coli was causative pathogen. Biochemical fingerprinting was performed to classify the isolates and select their appropriate representatives. Phylogenetic grouping was performed using multiplex PCR, and antibiotic resistance was deter- mined by disk diffusion method.

Results: Five-hundred-sixty E. coli isolates were derived from 56 UTI patients (27 acute, 29 recurrent). Among them, 261 isolates were selected using biochemical fingerprinting. All the isolates were sensitive to imipenem and nitrofurantoin. Com- pared to other phylo-groups, the isolates in group D showed considerably different frequencies in acute vs. recurrent phase of UTI, in urine vs. stool samples, in males vs. females, and in- vs. out-patients. They were more resistant to the antibiotics (except norfloxacin), and in contrast to others, this was seen more in acute UTI, especially in urine samples. Multi-drug resistance pattern was also meaningfully higher in group D.

Conclusion: Although phylo-groups B2 and D of E. coli bacteria are more responsible for UTI, group D isolates seem to be more resistant and probably more virulent, even than the ones from group B2.