Abstract
BackgroundTo identify the spread of nosocomial infections and halt outbreak development caused by Escherichia coli that carry multiple antibiotic resistance factors, such as extended-spectrum beta-lactamases (ESBLs) and carbapenemases, is becoming demanding challenges due to the rapid global increase and constant and increasing influx of these bacteria from the community to the hospital setting. Our aim was to assess a reliable and rapid typing protocol for ESBL-E. coli, with the primary focus to screen for possible clonal relatedness between isolates. All clinical ESBL-E. coli isolates, collected from hospitals (n = 63) and the community (n = 41), within a single geographical region over a 6 months period, were included, as well as clinical isolates from a polyclonal outbreak (ST131, n = 9, and ST1444, n = 3). The sporadic cases represented 36 STs, of which eight STs dominated i.e. ST131 (n = 33 isolates), ST648 (n = 10), ST38 (n = 9), ST12 and 69 (each n = 4), ST 167, 405 and 372 (each n = 3). The efficacy of multiple-locus variable number tandem repeat analysis (MLVA) was evaluated using three, seven or ten loci, in comparison with that of pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST).ResultsMLVA detected 39, 55 and 60 distinct types, respectively, using three (GECM-3), seven (GECM-7) or ten (GECM-10) loci. For GECM-7 and −10, 26 STs included one type and eleven STs each included several types, the corresponding numbers for GECM-3 were 29 and 8. The highest numbers were seen for ST131 (7,7 and 8 types, respectively), ST38 (5,5,8) and ST648 (4,5,5). Good concordance was observed with PFGE and GECM-7 and −10, despite fewer types being identified with MLVA; 78 as compared to 55 and 60 types. The lower discriminatory power of MLVA was primarily seen within the O25b-ST131 lineage (n = 34) and its H30-Rx subclone (n = 21). Epidemiologically unrelated O25b-ST131 isolates were clustered with O25b-ST131 outbreak isolates by MLVA, whereas the ST1444 outbreak isolates were accurately distinguished from unrelated isolates.ConclusionMLVA, even when using only three loci, represents an easy initial typing tool for epidemiological screening of ESBL-E. coli. For the ST131-O25b linage, complementary methods may be needed to obtain sufficient resolution.
Highlights
To identify the spread of nosocomial infections and halt outbreak development caused by Escherichia coli that carry multiple antibiotic resistance factors, such as extended-spectrum beta-lactamases (ESBLs) and carbapenemases, is becoming demanding challenges due to the rapid global increase and constant and increasing influx of these bacteria from the community to the hospital setting
We have previously reported on the successful application of a generic E. coli multiple-locus variable number tandem repeat analysis (MLVA) (GECM) that uses 10 loci, as described by Lobersli et al [23], to investigate a polyclonal plasmid-mediated ESBL-E. coli and K. pneumoniae outbreak [7, 24]
With the aim of deriving a typing method for ESBL-E. coli that can be used for standard consecutive infection control surveillance, we evaluated the efficacy of MLVA, using different numbers of loci, and compared it with pulsed-field gel electrophoresis (PFGE) and multi locus sequence typing (MLST), to distinguish consecutively identified ESBL-E. coli isolates, including the above mentioned outbreak isolates, in a municipal area in south-western Sweden whilst this longstanding, initially undetected, outbreak lasted
Summary
To identify the spread of nosocomial infections and halt outbreak development caused by Escherichia coli that carry multiple antibiotic resistance factors, such as extended-spectrum beta-lactamases (ESBLs) and carbapenemases, is becoming demanding challenges due to the rapid global increase and constant and increasing influx of these bacteria from the community to the hospital setting. Our aim was to assess a reliable and rapid typing protocol for ESBL-E. coli, with the primary focus to screen for possible clonal relatedness between isolates. Enterobacteriaceae that harbour resistance mechanisms, such as extended-spectrum beta-lactamases (ESBL) and carbapenemases, pose major threats to human health [2]. Data from the European Centre for Disease Prevention and Control (ECDC) surveillance program show that the prevalence of E. coli with resistance to third generation cephalosporins is still low in the Scandinavian countries [10]. Further data have demonstrated that the prevalence with regard to ESBL-producing Enterobacteriaceae is low, on the rise [11,12,13,14]
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