Clonal Diversity, Virulence Potential and Antimicrobial Resistance of Escherichia coli Causing Community Acquired Urinary Tract Infection in Switzerland.

Objectives: The aim of this study was to assess the clonal structure, virulence potential and antibiotic susceptibility of uropathogenic Escherichia coli (UPEC) isolates causing community acquired urinary tract infection (CAUTI) in unselected primary care patients in Switzerland. Methods: We performed multilocus sequence typing, virulence factor determination, and phenotypic and genotypic antimicrobial resistance testing on 44 non-duplicate UPEC isolates. Results: Twenty-seven different sequence types (STs) were identified. Major UPEC clones were represented by 19 (43.2%) of the isolates, including E. coli ST131, ST69 (both 13.6%), ST73 (6.8%), ST10 (4.5%), ST127, ST140, (both 2.3%). Five (11.4%) isolates belonged to ST141. Aggregate virulence factor (VF) scores were highest among isolates belonging to ST127 and ST141. Overall, 50% of the isolates were susceptible to all 12 antimicrobials tested, and all isolates remained susceptible to fosfomycin and nitrofurantoin. Resistance to sulfamethoxazole and ciprofloxacin were found in 31.8, and 15.9% of the isolates, respectively. Plasmid-mediated resistance genes were detected in ST69 and ST131 and included aac(6')-Ib-cr (2.3% of all isolates) blaCTX-M-14 and blaCTX-M-15 (9%), and mph(A) (13.6%). None of the isolates tested positive for mcr-1 or mcr-2. Conclusions: Our results show that CAUTI in Switzerland is caused by a wide variety of UPEC STs for which fosfomycin remains a good treatment option. We suggest that ST141 is an emerging clone associated with UTI in the community, and warrants closer attention. Moreover, the high rate of E. coli harboring mph(A) from patients without a history of antimicrobial therapy or hospitalization indicates that UPEC is an important reservoir for mph(A).

Emergence of Escherichia coli producing OXA-48 ß-lactamase in the community in Switzerland.

BACKGROUND: The emergence and worldwide spread of carbapenemase-producing Enterobacteriaceae is of great concern to public health services. The aim of this study was to investigate the occurrence of carbapenemase-producing Enterobacteriaceae in the community in Switzerland. FINDINGS: One thousand and eighty-six stool samples of healthy humans (staff members of a food-processing company which were screened for the occurrence of salmonellae) were collected in September 2014. After an initial enrichment-step, carbapenemase-producing Enterobacteriaceae were isolated from the carbapenem-containing selective medium SUPERCARBA II. Grown colonies from 11 samples were screened by PCR for the presence of bla KPC, bla NDM, bla OXA-48 and bla VIM. A single OXA-48-producing Escherichia coli was detected. Phylogenetic grouping and multi-locus sequence typing (MLST) revealed that this strain belonged to D:ST38, a type which had been previously reported in the UK, France, Lebanon and Egypt. CONCLUSIONS: The results of this study show that OXA-48-producing Enterobacteriaceae have started to spread into the community in Switzerland, and a continuous monitoring is necessary to better understand their dissemination in the human population as well as in animals and the environment.

Prevalence of subtilase cytotoxin-encoding subAB variants among Shiga toxin-producing Escherichia coli strains isolated from wild ruminants and sheep differs from that of cattle and pigs and is predominated by the new allelic variant subAB2-2.

Subtilase cytotoxin (SubAB) is an AB5 toxin produced by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains usually lacking the eae gene product intimin. Three allelic variants of SubAB encoding genes have been described: subAB1, located on a plasmid, subAB2-1, located on the pathogenicity island SE-PAI and subAB2-2 located in an outer membrane efflux protein (OEP) region. SubAB is becoming increasingly recognized as a toxin potentially involved in human pathogenesis. Ruminants and cattle have been identified as reservoirs of subAB-positive STEC. The presence of the three subAB allelic variants was investigated by PCR for 152 STEC strains originating from chamois, ibex, red deer, roe deer, cattle, sheep and pigs. Overall, subAB genes were detected in 45.5% of the strains. Prevalence was highest for STEC originating from ibex (100%), chamois (92%) and sheep (65%). None of the STEC of bovine or of porcine origin tested positive for subAB. None of the strains tested positive for subAB1. The allelic variant subAB2-2 was detected the most commonly, with 51.4% possessing subAb2-1 together with subAB2-2. STEC of ovine origin, serotypes O91:H- and O128:H2, the saa gene, which encodes for the autoagglutinating adhesin and stx2b were significantly associated with subAB-positive STEC. Our results suggest that subAB2-1 and subAB2-2 is widespread among STEC from wild ruminants and sheep and may be important as virulence markers in STEC pathogenic to humans.

Characteristics of enteroaggregative Escherichia coli isolated from healthy carriers and from patients with diarrhoea.

The aim of this study was to compare the virulence characteristics and phylogenetic features of enteroaggregative Escherichia coli (EAEC) strains from adults with and without diarrhoea and to search for associations between the analysed genes and carrier or diarrhoeagenic strains, respectively. Faecal samples of 487 healthy humans were screened for EAEC strains and compared with isolates from diarrhoeal patients. Virulence and virulence-associated gene typing, serotyping, multilocus sequence typing and antibiotic susceptibility testing were performed for characterization of the isolates. Characteristics significantly linked to carrier strains or to diarrhoeagenic strains were determined. From 487 stool samples, 24 EAEC strains were obtained. Comparison with strains originating from diseased persons showed a statistically significant association of the genes sat (P = 0.002) and agg3C (P = 0.0139) with the carrier strains, and of pCVD432 (P = 0.0001), aap (P = 0.003), aggR (P = 0.0048) and air (P = 0.031) with the diarrhoeagenic strains. Our study indicates that a certain subset of EAEC is unrelated to diarrhoea, for which sat and agg3C may be markers. Our results further suggest that diarrhoeagenic EAEC strains are distinguishable from carrier strains and suggest that, in addition to well-established markers such as pCVD432 and aggR, aap and air may be useful additional markers to define EAEC as an aetiological agent of diarrhoea in adults.

Cross-sectional study on fecal carriage of Enterobacteriaceae with resistance to extended-spectrum cephalosporins in primary care patients.

The aim of this study was to gain knowledge of the local epidemiology of extended-spectrum cephalosporin-resistant bacteria in primary care patients in a Swiss community. Fecal swabs were obtained from 291 primary care patients. Phenotyping and genotyping methods were used for further characterization of the isolates. Risk factors associated with carriage of ß-lactam-resistant strains were determined. Extended-spectrum cephalosporin-resistant Enterobacteriaceae were detected in 15 (5.2%) of the primary care patients. Thirteen isolates were CTX-M producers, one produced SHV-12, and three carried CMY-2. The pathogenic pandemic clone Escherichia coli ST131 was detected in 26.6% of the patients. Two patients (13.3%) carried two distinct strains simultaneously. There was a statistically significant risk of carriage of resistant strains for persons with a history of antibiotic therapy 4 months before sampling (p=0.05), markedly for therapy with ß-lactam (p=0.01). Age, gender, or history of hospitalization 4 months before sampling was not a risk factor for the acquisition of resistant bacteria in the analyzed patients. The relatively low prevalence of extended-spectrum cephalosporin-resistant strains in the community reflects the nationwide restrictive policy of antibiotic prescription as well as local implementation thereof. Nevertheless, our study shows that a potent antimicrobial resistance reservoir is present in primary care patients.