Molecular epidemiology of fosfomycin resistance and effect on biological properties in clinical Enterobacteriaceae isolates
Project no. 21813 · Status: Kapanmış · 2020
Summary
<p>Fosfomycin has a different mechanism of action from other antibiotics and does not cause</p><p>cross-resistance. Also its activity against many gram-positive and ESBL-positive gramnegative</p><p>bacteria makes fosfomycin a point of interest. It is thought that the use of fosfomycin</p><p>against Escherichia coli and Klebsiella pneumoniae isolates, will increase because infections</p><p>of these microorganisms are difficult to treat due to various virulence factors and increasing</p><p>antibiotic resistance rates. Therefore it is important to foresee the possible effects of expanding</p><p>the use of fosfomycin. In our study, we aimed to examine the possible differences between the</p><p>virulence factors of fosfomycin-resistant and susceptible E. coli and K. pneumoniae strains</p><p>from a phenotypic and molecular point of view. A total of 112 strains, constitute of 78 E. coli</p><p>and 34 K. pneumoniae isolated from different clinical specimens at Ege University Medical</p><p>Faculty Hospital, were included in the study. The minimum inhibitory concentrations of</p><p>fosfomycin of the strains were determined by agar dilution method. 13 (16.66%) of 78 E. coli</p><p>strains and 8 (23.5%) of 34 K. pneumoniae strains were found to be resistant to fosfomycin. In</p><p>the fosfomycin resistant E. coli (13) and K. pneumoniae (8) strains, genes related to resistance</p><p>(murA, glpT, uhpT, fos), adhesion (fimH, papC, mrkD), polysaccharides in the capsule structure</p><p>(uge, ycfM, wabG), gene involved in uropathogenicity (usp) and siderophore synthesis (entb)</p><p>gene have been investigated. Then, fosfomycin-sensitive 2 E. coli and 2 K. pneumoniae strains</p><p>were made resistant by passaging into media containing increasing concentrations of</p><p>fosfomycin. Then, expression levels of virulence genes, biofilm forming capacities and growth</p><p>rates of these resistant and susceptible isogenic variants were compared. There weren’t any</p><p>significant changes between the expression levels of the most of the virulence genes examined</p><p>when fosfomycin resistant and susceptible isogenic variants were compared by quantitative</p><p>real-time polymerase chain reaction (RT-qPCR). Biofilm forming capacities of the resistant</p><p>and susceptible variants were compared with the spectrophotometric crystal violet method and</p><p>no significant difference was found between them. Fosfomycin resistant and susceptible</p><p>variants were incubated in broth media for 10 hours, and the growth rates were compared by</p><p>measuring the absorbance at 600nm wavelength by taking samples from the tubes every 2</p><p>hours. In three of the four bacterial variant pairs examined, we observed that the susceptible</p><p>variants grew significantly faster than the resistant ones but there was no significant difference</p><p>between the susceptible and resistant variants of one strain. The data of our study indicate that</p><p>although the growth rates of fosfomycin-resistant E. coli and K. pneumoniae strains are</p><p>reduced, fosfomycin resistance didn’t pose any significant disadvantage in terms of virulence</p><p>factors. Therefore the use of fosfomycin should be carefully monitored.</p>