Dam methylation has profound effect on antibiotic resistance in uropathogenic Escherichia coli

Medical Microbiology & Diagnosis

ISSN: 2161-0703

Open Access

Dam methylation has profound effect on antibiotic resistance in uropathogenic Escherichia coli

Joint Conference International Congress on Nosocomial and Healthcare Associated Infections & 2nd Global Medical Microbiology Summit & Expo

October 02-04, 2017 Las Vegas, USA

Paul D Brown

The University of the West Indies, Jamaica

Posters & Accepted Abstracts: J Med Microb Diagn

Abstract :

Urinary tract infections (UTIs) are primarily caused by uropathogenic Escherichia coli (UPEC) bacteria and result in high morbidity and high economic costs. Because many of these bacteria are resistant to standard therapeutic strategies, the need for alternative strategies arises. Since differential DNA methylation is often observed in pathogenic gene regulation, this study sought to assess the influence of DNA methylation (mediated by the dam gene) on antibiotic resistance regulation in UPEC strains and its potential as a therapeutic target. We knocked out the dam gene in selected UPEC strains via one-step allelic exchange, and assessed growth rate, susceptibility to antibiotics, and ability to form biofilms in the presence of antibiotics and oxidative stress in these dam mutants. To restore dam function, mutants were complemented with a plasmid containing the dam gene and the qnrA gene (where appropriate). The absence of DNA methylation among dam mutants was apparent: ├?┬?dam mutant cells were elongated and filamentous; had ├ó┬?┬Ą2-fold reduced growth rate, cell numbers and an extended lag phase (90-180 min). Further, there was an 8-fold decrease in resistance for strain cC119 versus cC119├?┬?dam against amoxicillin/clavulanic acid (AMC), trimethoprim/sulfamethoxazole (SXT) and gentamicin, and 4-fold against ciprofloxacin. Finally, there were increases in biofilm formation (including in the presence of oxidative stress) by the mutants relative to the parental strains. Phenotypic characteristics of parental strains were restored in dam-complemented strains. It was clear that the dam gene plays a vital role in DNA methylation and antibiotic resistance in UPEC strains.

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