Carriage of extended-spectrum β-lactamases in pig farmers is associated with occurrence in pigs.

Livestock may serve as a reservoir for extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE). The objectives of this study were to determine the prevalence of carriage with ESBL-PE in pig farmers, family members and employees, and its association with carriage in pigs. Rectal swabs were taken from 2388 pigs (398 pooled samples) on 40 pig farms and faecal samples were obtained from 142 humans living or working on 34 of these farms. Presence of ESBL-PE was determined by selective plating (agar). ESBL genes were analysed by PCR or microarray analysis, and gene sequencing. Genotypes and plasmids were determined by multilocus sequence typing and PCR-based replicon typing for selected isolates. ESBL genes were detected in Escherichia coli from eight humans (6%) (blaCTX-M-1, n = 6; blaTEM-52, n = 1 and blaCTX-M-14, n = 1) on six farms. In 157 pig isolates (107 pooled samples) on 18 farms (45%) ESBL genes were detected (blaCTX-M-1, n = 12; blaTEM-52, n = 6; and blaCTX-M-14, n = 3). Human and pig isolates within the same farm harboured similar ESBL gene types and had identical sequence and plasmid types on two farms (e.g. E. coli ST-453, blaCTX-M-1, IncI1), suggesting clonal transmission. For the remaining farms, sequence types, but not plasmid types, differed. Human ESBL carriage was associated with average number of hours working on the farm per week (OR = 1.04, 95% CI 1.02-1.06) and presence of ESBLs in pigs (OR = 12.5, 95% CI 1.4-111.7). Daily exposure to pigs carrying ESBL-PE is associated with ESBL carriage in humans.

Dohmen W ，Bonten MJ ，Bos ME ，van Marm S ，Scharringa J ，Wagenaar JA ，Heederik DJ ... -  《-》

Air exposure as a possible route for ESBL in pig farmers.

Livestock can carry extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, with blaCTX-M-1 being most prevalent. ESBL carriage in farmers is associated with ESBL carriage in animals, with direct animal-human contact considered as the dominant route of transmission. However, inhalation of stable air might represent another route of transmission. We, therefore, quantified presence of blaCTX-M group 1 genes (CTX-M-gr1) in dust and the association with CTX-M-gr1 carriage in pig farmers, family members and employees. We included 131 people living and/or working on 32 conventional Dutch pig production farms (farmers, family members and employees) during two sampling moments over a 12-month interval. Human stool samples, rectal swabs from 60 pigs per farm, and 2-5 dust samples collected using an electrostatic dust collector (EDC) (as a proxy for presence of viable CTX-M-gr1 carrying bacteria in air) were obtained per farm. Presence of ESBL-producing Escherichia Coli (E. coli) in stool samples and rectal swabs was determined by selective plating and CTX-M-gr1 was identified by PCR. Dust samples were analyzed directly by PCR for presence of CTX-M-gr1. Questionnaires were used to collect information on nature, intensity and duration of animal contact. Overall human prevalence of CTX-M-gr1 carriage was 3.6%. CTX-M-gr1 was detected in dust on 26% of the farms and in pigs on 35% of the farms, on at least one sampling moment. Human CTX-M-gr1 carriage and presence of CTX-M-gr1 in dust were associated univariately (OR=12.4, 95% CI=2.7-57.1). In multivariate analysis human CTX-M-gr1 carriage was associated with the number of working hours per week (OR=1.03, 95% CI=1.00-1.06), presence of CTX-M-gr1 carrying pigs on the farm (OR=7.4, 95% CI=1.1-49.7) and presence of CTX-M-gr1 in dust (OR=3.5, 95% CI=0.6-20.9). These results leave open the possibility of airborne CTX-M-gr1 transmission from animals to humans next to direct contact.

Dohmen W ，Schmitt H ，Bonten M ，Heederik D ... -  《-》

Characterization of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli obtained from Danish pigs, pig farmers and their families from farms with high or no consumption of third- or fourth-generation cephalosporins.

To compare and characterize extended-spectrum β-lactamase (ESBL)-producing Escherichia coli from pigsties, pig farmers and their families on farms with previous high or no use of third- or fourth-generation cephalosporins. Twenty farms with no third- or fourth-generation cephalosporin use and 19 herds with previous frequent use were included. The ESBL-producing isolates detected in humans and pigs were characterized by ESBL genotype, PFGE, susceptibility to non-β-lactam antibiotics and phylotype, and selected isolates were characterized by multilocus sequence typing (MLST). Furthermore, transferability of bla(CTX-M-)1 from both human and pig isolates was studied and plasmid incompatibility groups were defined. The volunteers answered a questionnaire including epidemiological risk factors for carriage of ESBL-producing E. coli. ESBL-producing E. coli was detected in pigs on 79% of the farms with high consumption of cephalosporins compared with 20% of the pigs on farms with no consumption. ESBL-producing E. coli was detected in 19 of the 195 human participants and all but one had contact with pigs. The genes found in both humans and pigs at the same farms were blaCTX-M-1 (eight farms), bla(CTX-M-14) (one farm) and bla(SHV-12) (one farm). At four farms ESBL-producing E. coli isolates with the same CTX-M enzyme, phylotype, PFGE type and MLST type were detected in both pigs and farmers. The majority of the plasmids with bla(CTX-M-1) were transferable by conjugation and belonged to incompatibility group IncI1, IncF, or IncN. The present study shows an increased frequency of ESBL-producing E. coli on farms with high consumption of third- or fourth-generation cephalosporins and indicates transfer of either ESBL-producing E. coli or plasmids between pigs and farmers.

Hammerum AM ，Larsen J ，Andersen VD ，Lester CH ，Skovgaard Skytte TS ，Hansen F ，Olsen SS ，Mordhorst H ，Skov RL ，Aarestrup FM ，Agersø Y ... -  《-》

Colonization with extended-spectrum beta-lactamase-producing and carbapenemase-producing Enterobacteriaceae in international travelers returning to Germany.

Two hundred and twenty-five healthy German volunteers traveling to 53 different countries (mostly in Asia, Africa and South America) were enrolled in a prospective cohort study. Stool samples and data on potential travel-associated risk factors (such as type of travel, nutritional habits, occurrence of gastroenteritis) were collected before and after traveling. Screening for extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) and carbapenemase-producing Enterobacteriaceae (CPE) was performed using selective media (CHROMagar™ ESBL/CPE plates). Isolates with confirmed ESBL-phenotype were examined for the presence of blaCTX-M, blaTEM, blaSHV, and blaVIM, blaIMP, blaNDM, blaKPC, blaOXA-48 genes by PCR amplification and sequencing. Antimicrobial susceptibility testing was performed using conventional microbroth dilution. Pre-travel analysis of 205 fully evaluable participants revealed an ESBL-PE prevalence rate of 6.8% (14/205). Among 191 participants that were ESBL-negative before travel, 58 (30.4%) were colonized by ESBL-producing Escherichia coli, and 5 (8.6%) additionally carried ESBL-producing Klebsiella pneumoniae upon return. However, no carbapenem-resistant Enterobacteriaceae were detected. ESBL-genotyping revealed that 52/54 (96.6%) E. coli and 4/4 (100%) K. pneumoniae strains available for sequencing produced CTX-M enzymes, mostly CTX-M-15 (33/56, 58.9%), and 2/54 (3.7%) E. coli strains produced SHV-12 enzymes. Travel to India was associated with the highest ESBL-PE acquisition rate (11/15, 73.3%; p=0.015), followed by South East Asia (22/46, 47.8%; p=0.038). Evaluation of travel-associated risk factors demonstrated significance for the occurrence of gastroenteritis (p=0.011). Strictly practiced hand hygiene and exclusive consumption of packaged beverages showed no protective effect. The ESBL-PE persistence rate after 6 months was 8.6% (3/35). We conclude that global efforts are needed to address the further spread of ESBL-PE in the community. Active surveillance and contact isolation precautions may be recommended at admission to medical facilities especially for patients who traveled to India and South East Asia in the previous 6 months.

Lübbert C ，Straube L ，Stein C ，Makarewicz O ，Schubert S ，Mössner J ，Pletz MW ，Rodloff AC ... -  《-》

Simultaneous occurrence of MRSA and ESBL-producing Enterobacteriaceae on pig farms and in nasal and stool samples from farmers.

Methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL) producing enterobacteria (ESBL-E) have emerged in livestock. This study prospectively investigates the prevalence of MRSA and ESBL-E on pig farms and in nasal and stool samples from farmers and compares molecular characteristics of these ESBL-E isolates. In 2014, samples were derived at 51 pig farms in Germany. Per farm, five dust and five fecal samples were collected; one nasal and one stool sample were retrieved from farmers. ESBL-E isolates from humans and environmental isolates from the respective farms were characterized using whole genome sequencing for classical multilocus sequence typing (MLST), determination of ESBL-encoding genes and an ad hoc core genome MLST (cgMLST) analysis. MRSA and ESBL-E were detected on 49 (96%) and 31 (61%) of the farms, respectively; in most cases (59%) simultaneously. Nasal MRSA carriage was detected in 72 of 85 (84.7%) farmers and five of 84 (6.0%) farmers carried ESBL-E. ESBL-Escherichia coli isolates from farmers belonged to MLST STs/ESBL-genes ST10/CTX-M-1, ST196/TEM-52, ST278/TEM-52, ST410/CTX-M-15 and ST453/CTX-M-1. In one case, the human ESBL-E isolate was clonally identical to isolates from the farm environment; in the other four cases typing results indicated potential exchange of resistance determinants between human and environmental isolates, but, comparing the isolates within a minimum spanning tree indicated differences in cgMLST-patterns between the farms (p=0.076). This study demonstrated rectal ESBL-E carriage rates among farmers, which were similar to those in the general population. Molecular typing suggested that cross-transmission between the farmers and the farm environment is possible.

Fischer J ，Hille K ，Ruddat I ，Mellmann A ，Köck R ，Kreienbrock L ... -  《-》