Extended-spectrum beta-lactamases (ESBL) mediating resistance to 3rd generation cephalosporins are a major public health issue. As food may be a vehicle in the spread of ESLB-producing bacteria, a study on the occurrence of cephalosporin-resistantu Escherichia coli in food was initiated. A total of 404 ESBL-producing isolates were obtained from animal-derived food samples (e.g., poultry products, pork, beef and raw milk) between 2011 and 2013. As CTX-M-15 is the most abundant enzyme in ESBL-producing E. coli causing human infections, this study focusses on E. coli isolates from food samples harboring the blaCTX-M-15 gene. The blaCTX-M-15 gene was detected in 5.2% (n = 21) of all isolates. Molecular analyses revealed a phylogenetic group A ST167 clone that was repeatedly isolated from raw milk and beef samples over a period of 6 months. The analyses indicate that spread of CTX-M-15-producing E. coli in German food samples were associated with a multireplicon IncF (FIA FIB FII) plasmid and additional antimicrobial resistance genes such as aac(6)-Ib-cr, blaOXA−1, catB3, different tet-variants as well as a class 1 integron with an aadA5/dfrA17 gene cassette. In addition, four phylogenetic group A ST410 isolates were detected. Three of them carried a chromosomal copy of the blaCTX-M-15 gene and a single isolate with the gene on a 90 kb IncF plasmid. The blaCTX-M-15 gene was always associated with the ISEcp1 element. In conclusion, CTX-M-15-producing E. coli were detected in German food samples. Among isolates of different matrices, two prominent clonal lineages, namely A-ST167 and A-ST410, were identified. These lineages may be important for the foodborne dissemination of CTX-M-15-producing E. coli in Germany. Interestingly, these clonal lineages were reported to be widely distributed and especially prevalent in isolates from humans and livestock. Transmission of CTX-M-15-harboring isolates from food-producing animals to food appears probable, as isolates obtained from livestock and food samples within the same time period exhibit comparable characteristics as compared to isolates detected from human. However, the routes and direction of transmission need further investigation.

Antimicrobial resistance to cephalosporins is commonly mediated by extended-spectrum β-lactamases (ESBL) or plasmidic AmpC β-lactamases (pAmpC). In livestock bla is the most frequently detected ESBL-encoding gene. As transmission to consumers through contaminated food is often proposed, this study characterized ESBL/pAmpC-producing E. coli collected from food samples. Therefore, samples from food products of animal origin and vegetables were screened for phenotypically resistant E. coli by selective cultivation. The ESBL genotype was confirmed for 404 isolates with the majority of them (n = 212) harboring the bla gene. PFGE and MLST analyses as well as plasmid characterization were carried out for 89 isolates, selected under epidemiological aspects. In addition, 44 isolates were investigated by whole genome sequencing and/or sequencing of their plasmids on an Illumina Miseq platform. MLST and PFGE indicated a diverse population of CTX-M-1-producing E. coli in German food samples with no spread of single clonal lineages. The majority of the isolates harbored the bla gene on IncI1 plasmids. Frequently, the gene was associated with the ISEcp1 element and located on a ∼100 kb IncI1 plasmid depicting the plasmid multilocus sequence type (ST) 3. The bla gene and its flanking sequences were located within the shufflon of the type IV pilus region in diverse orientations. In conclusion, dissemination of the CTX-M-1 β-lactamase within food samples of animal origin is driven by the transmission of a ∼100 kb large IncI1 ST3 plasmid. Apart from conjugal transfer of IncI1 ST3 plasmids the transmission of the bla gene might be further promoted through mobilization due to its location within a recombination hot-spot of IncI1 plasmids.

The prevalence of CTX-M-₁₅-producing isolates from non-human sources in Germany is still low. The blaCTX-M-₁₅ gene is, however, present in multidrug-resistant E. coli clones with pathogenic potential in livestock and food. The maintenance of the blaCTX-M-₁₅ gene due to chromosomal carriage is noteworthy. The possibility of an exchange of CTX-M-₁₅-producing isolates or plasmids between livestock and humans (in both directions) deserves continuous surveillance.

Vaginal Escherichia coli colonization is related to obstetric infections and the consequent development of infections in newborns. Ampicillin resistance among E. coli strains is increasing, which is the main choice for treating empirically many obstetric and neonatal infections. Vaginal E. coli strains are very similar to extraintestinal pathogenic E. coli with regards to the virulence factors and the belonging to phylogroup B2. We studied the antimicrobial resistance and the genetic virulence profile of 82 E. coli isolates from 638 vaginal samples and 63 isolated from endometrial aspirate, placental and amniotic fluid samples from pregnant women with obstetric infections. The prevalence of E. coli in the vaginal samples was 13%, which was significant among women with associated risk factors during pregnancy, especially premature preterm rupture of membranes (p<0.0001). Sixty-five percent of the strains were ampicillin-resistant. The E. coli isolates causing obstetric infections showed higher resistance levels than vaginal isolates, particularly for gentamicin (p = 0.001). The most prevalent virulence factor genes were those related to the iron uptake systems revealing clear targets for interventions. More than 50% of the isolates belonged to the virulent B2 group possessing the highest number of virulence factor genes. The ampicillin-resistant isolates had high number of virulence factors primarily related to pathogenicity islands, and the remarkable gentamicin resistance in E. coli isolates from women presenting obstetric infections, the choice of the most appropriate empiric treatment and clinical management of pregnant women and neonates should be carefully made. Taking into account host-susceptibility, the heterogeneity of E. coli due to evolution over time and the geographical area, characterization of E. coli isolates colonizing the vagina and causing obstetric infections in different regions may help to develop interventions and avoid the aetiological link between maternal carriage and obstetric and subsequent puerperal infections.

Escherichia coli are enteric Gram-negative bacilli that can colonize the female genital tract and become implicated in different infections in pregnant women, including intra-amniotic infection, puerperal infections and neonatal infections. The virulence profiles of E. coli isolates from vaginal swabs from pregnant and nonpregnant women were compared. The hly-, cnf-, pap- and iroN-genes were found significantly more frequently in E. coli isolated from pregnant women in comparison with those isolated from nonpregnant women. Escherichia coli from pregnant women seem to be more virulent than from nonpregnant women developing severe infections, thereby increasing possible neonatal sepsis.

The objective of this study was to assess the antimicrobial resistance of enteroaggregative Escherichia coli (EAEC) and enterotoxigenic E. coli (ETEC) strains causing traveler’s diarrhea (TD) and to investigate the molecular characterization of antimicrobial resistance genes to third-generation cephalosporins, cephamycins, and quinolones. Overall, 39 EAEC and 43 ETEC clinical isolates were studied. The susceptibilities of EAEC and ETEC against ampicillin, amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, tetracycline, co-trimoxazole, nalidixic acid, ciprofloxacin, azithromycin, and rifaximin were determined. All genes encoding resistance determinants were detected by PCR or PCR plus DNA sequencing. The epidemiology of selected EAEC and ETEC strains was studied using multilocus sequence typing (MLST). The resistance to quinolones of EAEC and ETEC strains causing TD has significantly increased over the last decades, and high percentages have been found especially in patients traveling to India and sub-Saharan Africa. Sequence type 38 (ST38) and ST131, carrying the blaCTX-M-15 and blaCTX-M-27 genes, respectively, are highly prevalent among extended-spectrum β-lactamase (ESBL)-producing EAEC and ETEC strains. The cephamycinase ACT-20 is described in the present study for the first time in EAEC and ETEC strains causing TD in patients who had traveled to Central America. The percentages of resistance to azithromycin in EAEC and ETEC isolates from patients to Southeast Asia/India and Africa are above 25%. Meanwhile, rifaximin is still active against EAEC and ETEC, with the prevalence of resistant strains not being high. In conclusion, fluoroquinolones should no longer be considered the drugs of choice for the prevention or treatment in TD for travelers traveling to India and Africa. Azithromycin and rifaximin are still a good alternative to treat TD caused by EAEC or ETEC.

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Travelers’ diarrhea is a major public health problem. From patients in whom diarrhea developed after travel to India, 5 enteroaggregative Escherichia coli strains carrying β-lactamase CTX-M-15 were identified; 3 belonged to clonal complex sequence type 38. This β-lactamase contributes to the multidrug resistance of enteroaggregative E. coli, thereby limiting therapeutic alternatives.