The CTX-M Conundrum: Dissemination of Plasmids andEscherichia coliClones

Abstract

The ongoing global spread and increased prevalence of CTX-M-type extended-spectrum β-lactamases in Enterobacteriaceae is of great concern. The successful distribution of CTX-M enzymes mainly involves Escherichia coli causing systemic as well as urinary tract infections in patients worldwide. CTX-M expression is often associated with coresistance that critically reduces treatments options. The mobilization of bla(CTX-M) genes from their original chromosomal position in various Kluyvera species has been facilitated by mobile genetic elements such as ISEcp1 or ISCR1. Molecular epidemiological studies have revealed a thriving linkage of bla(CTX-M) genes to conjugative plasmids and successful bacterial clones. Multireplicon FII plasmids are shown to carry the most widely distributed bla(CTX-M-15) across continents, paving the way for bla(CTX-M-15) into different genetic lineages of E. coli. Dissemination of virulent clones ST131-O25:H4-B2 and ST405-O102:H6-D is now being described worldwide. Importantly, CTX-M-producing strains are uncovering their ability of long-term gastrointestinal colonization often associated with travel to high-prevalent areas. Thus, we are witnessing a global epidemic of bla(CTX-M)-encoding E. coli strains and plasmids, which require serious attention and efficient infection control measures.

High prevalence of Escherichia coli sequence type 131 among antimicrobial-resistant E. coli isolates from geriatric patients

“…Discordant therapy may cause treatment failure, persistence and recurrence of infection, leading to more patient morbidity and mortality (Barber et al, 2013;Shin et al, 2012). Emerging resistance in E. coli involves acquisition of resistance determinants by susceptible strains and the expansion of pre-existing resistant clones (Naseer & Sundsfjord, 2011). ST131 is a highly successful E. coli clone which has received considerable attention due to its wide geographical distribution, ability to cause a wide range of extra-intestinal infections and association with CTX-M b-lactamases and multidrug resistance (NicolasChanoine et al, 2014).…”

Clonal diversity of CTX-M-producing, multidrug-resistant Escherichia coli from rodents

“…Our findings showed that a large proportion (47.8 %, 33/ 69; Table 2) of CTX-M producing isolates were present in six successful bacterial clones (STC10/phylogroup A, STC23/phylogroup B1, STC38/phylogroup D, STC155/ phylogroup B1, ST405/phylogroup D and ST131/phylogroup B2) with a strong linkage to CTX-M dissemination (Naseer & Sundsfjord, 2011). ST131 and ST405 are virulent clones that have been found globally among disease isolates from human (Banerjee et al, 2013;Ho et al, 2012b).…”

“…Hence, the findings may not accurately reflect the situation in big cities. In addition, only small numbers (,10 isolates) of CTX-Mproducing E. coli isolates from rodents have been characterized (Guenther et al, 2012(Guenther et al, , 2013, thereby limiting the inference that could be made about their clonal distribution and zoonotic risk (Naseer & Sundsfjord, 2011). Here, we studied the prevalence of faecal carriage of ESBLproducing E. coli in a large sample of rats collected from all districts in a metropolitan city.…”

Rapid Detection of Extended-Spectrum Beta-Lactamases by Flow Cytometry Method

“…bla TEM ve bla SHV genlerinden köken alan GSBL enzimleri, 1980'li yıllarda yaygın iken, 2000'li yıllarda yerlerini CTX-M tipi enzimlere bırakmışlardır. CTX-M tipi enzimler, TEM ve SHV'nin aksine, bakteride önceden bulunan bir genin mutasyonuna bağlı olarak oluşmamıştır 1,2 .…”