Abstract
BackgroundFluoroquinolone resistant E. coli isolates, that are also resistant to other classes of antibiotics, is a significant challenge to antibiotic treatment and infection control policies. In Central Greece a significant increase of ciprofloxacin-resistant Escherichia coli has occurred during 2011, indicating the need for further analysis.MethodsA total of 106 ciprofloxacin-resistant out of 505 E. coli isolates consecutively collected during an eight months period in a tertiary Greek hospital of Central Greece were studied. Antimicrobial susceptibility patterns and mechanisms of resistance to quinolones were assessed, whereas selected isolates were further characterized by multilocus sequence typing and β-lactamase content.ResultsSequence analysis of the quinolone-resistance determining region of the gyrA and parC genes has revealed that 63% of the ciprofloxacin-resistant E. coli harbored a distinct amino acid substitution pattern (GyrA:S83L + D87N; ParC:S80I + E84V), while 34% and 3% carried the patterns GyrA:S83L + D87N; ParC:S80I and GyrA:S83L + D87N; ParC:S80I + E84G respectively. The aac (6’)-1b-cr plasmid-mediated quinolone resistance determinant was also detected; none of the isolates was found to carry the qnrA, qnrB and qnrS.Genotyping of a subset of 35 selected ciprofloxacin-resistant E. coli by multilocus sequence typing has revealed the presence of nine sequence types; ST131 and ST410 were the most prevalent and were exclusively correlated with hospital and health care associated infections, while strains belonging to STs 393, 361 and 162 were associated with community acquired infections. The GyrA:S83L + D87N; ParC:S80I + E84V substitution pattern was found exclusively among ST131 ciprofloxacin-resistant E. coli. Extended-spectrum β-lactamase-positive ST131 ciprofloxacin-resistant isolates produced CTX-M-type enzymes; eight the CTX-M-15 and one the CTX-M-3 variant. CTX-M-1 like and KPC-2 enzymes were detected in five and four ST410 ciprofloxacin-resistant E. coli isolates, respectively.ConclusionsOur findings suggest that, ST131 and ST410 predominate in the ciprofloxacin resistant E. coli population.
Highlights
Fluoroquinolone resistant E. coli isolates, that are resistant to other classes of antibiotics, is a significant challenge to antibiotic treatment and infection control policies
The nucleotide sequences of gyrA/ parC gene fragments of the 36 ciprofloxacin resistant (CIP-R) isolates with the GyrA:S83L + D87N; ParC:S80I substitution pattern were found to be more polymorphic
The majority of CIP-R E. coli belonged to ST131 and ST410, which were recovered from hospital and health care associated infections, whereas other studies have shown that such strains were disseminated in the community [11,12,13,14,15,16]
Summary
Fluoroquinolone resistant E. coli isolates, that are resistant to other classes of antibiotics, is a significant challenge to antibiotic treatment and infection control policies. In Central Greece a significant increase of ciprofloxacin-resistant Escherichia coli has occurred during 2011, indicating the need for further analysis. Quinolones are widely used antimicrobials for the treatment of bacterial infections [2] Their wide use has triggered increased bacterial resistance worldwide. In Greece, according to the recent data of WHONET the rate of ciprofloxacin resistant (CIP-R) E. coli varied from hospital to hospital and ranged from 5.6 to 49.5%. In the University Hospital of Larissa (UHL), that is the main tertiary hospital of Central Greece and serves a region of 1,000,000 habitants, an increase of ciprofloxacin-resistant E. coli from 16.3% in 2010 to 21% in 2011 was recorded. The aim of this study was to assess the epidemiological traits, mechanisms of resistance to fluoroquinolones, phylogenetic relationship and co-existing mechanism of resistance to newer β-lactams of CIP-R E. coli strains isolated in our institution during 2011
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