Gene pool transmission of multidrug resistance among Campylobacter from livestock, sewage and human disease.

The use of antimicrobials in human and veterinary medicine has coincided with a rise in antimicrobial resistance (AMR) in the food-borne pathogens Campylobacter jejuni and Campylobacter coli. Faecal contamination from the main reservoir hosts (livestock, especially poultry) is the principal route of human infection but little is known about the spread of AMR among source and sink populations. In particular, questions remain about how Campylobacter resistomes interact between species and hosts, and the potential role of sewage as a conduit for the spread of AMR. Here, we investigate the genomic variation associated with AMR in 168 C. jejuni and 92 C. coli strains isolated from humans, livestock and urban effluents in Spain. AMR was tested in vitro and isolate genomes were sequenced and screened for putative AMR genes and alleles. Genes associated with resistance to multiple drug classes were observed in both species and were commonly present in multidrug-resistant genomic islands (GIs), often located on plasmids or mobile elements. In many cases, these loci had alleles that were shared among C. jejuni and C. coli consistent with horizontal transfer. Our results suggest that specific antibiotic resistance genes have spread among Campylobacter isolated from humans, animals and the environment.

ant(6)-I Genes Encoding Aminoglycoside O-Nucleotidyltransferases Are Widely Spread Among Streptomycin Resistant Strains of Campylobacter jejuni and Campylobacter coli.

Thermotolerant Campylobacter species C. jejuni and C. coli are actually recognized as the major bacterial agent responsible for food-transmitted gastroenteritis. The most effective antimicrobials against Campylobacter are macrolides and some, but not all aminoglycosides. Among these, susceptibility to streptomycin is reduced by mutations in the ribosomal RPSL protein or by expression of ANT(6)-I aminoglycoside O-nucleotidyltransferases. The presence of streptomycin resistance genes was evaluated among streptomycin-resistant Campylobacter isolated from humans and animals by using PCR with degenerated primers devised to distinguish ant(6)-Ia, ant(6)-Ib and other ant-like genes. Genes encoding ANT(6)-I enzymes were found in all possible combinations with a major fraction of the isolates carrying a previously described ant-like gene, distantly related and belonging to the new ant(6)-I sub-family ant(6)-Ie. Among Campylobacter isolates, ant(6)-Ie was uniquely found functional in C. coli, as shown by gene transfer and phenotype expression in Escherichia coli, unlike detected coding sequences in C. jejuni that were truncated by an internal frame shift associated to RPSL mutations in streptomycin resistant strains. The genetic relationships of C. coli isolates with ANT(6)-Ie revealed one cluster of strains presented in bovine and humans, suggesting a circulation pathway of Campylobacter strains by consuming contaminated calf meat by bacteria expressing this streptomycin resistance element.

Antimicrobial Resistance in the Food Chain in the European Union.

Consumers require safety foods but without losing enough supply and low prices. Food concerns about antimicrobial residues and antimicrobial-resistant (AMR) bacteria are not usually appropriately separated and could be perceived as the same problem. The monitoring of residues of antimicrobials in animal food is well established at different levels (farm, slaughterhouse, and industry), and it is preceded by the legislation of veterinary medicines where maximum residues limits are required for medicines to be used in food animal. Following the strategy of the World Health Organization, one of the proposed measures consists in controlling the use of critical antibiotics. The European Union surveillance program currently includes the animal species with the highest meat production (pigs, chickens, turkeys, and cattle) and the food derived from them, investigating antimicrobial resistance of zoonotic (Salmonella and Campylobacter) and indicator (Escherichia coli and enterococci) bacteria. AMR mechanisms encoded by genes have a greater impact on transfer than mutations. Sometimes these genes are found in mobile genetic elements such as plasmids, transposons, or integrons, capable of passing from one bacterium to another by horizontal transfer. It is important to know that depending on how the resistance mechanism is transferred, the power of dissemination is different. By vertical transfer of the resistance gene, whatever its origin, will be transmitted to the following generations. In the case of horizontal transfer, the resistance gene moves to neighboring bacteria and therefore the range of resistance can be much greater.

Genome Comparison of Erythromycin Resistant Campylobacter from Turkeys Identifies Hosts and Pathways for Horizontal Spread of erm(B) Genes.

Pathogens in the genus Campylobacter are the most common cause of food-borne bacterial gastro-enteritis. Campylobacteriosis, caused principally by Campylobacter jejuni and Campylobacter coli, is transmitted to humans by food of animal origin, especially poultry. As for many pathogens, antimicrobial resistance in Campylobacter is increasing at an alarming rate. Erythromycin prescription is the treatment of choice for clinical cases requiring antimicrobial therapy but this is compromised by mobility of the erythromycin resistance gene erm(B) between strains. Here, we evaluate resistance to six antimicrobials in 170 Campylobacter isolates (133 C. coli and 37 C. jejuni) from turkeys. Erythromycin resistant isolates (n = 85; 81 C. coli and 4 C. jejuni) were screened for the presence of the erm(B) gene, that has not previously been identified in isolates from turkeys. The genomes of two positive C. coli isolates were sequenced and in both isolates the erm(B) gene clustered with resistance determinants against aminoglycosides plus tetracycline, including aad9, aadE, aph(2″)-IIIa, aph(3')-IIIa, and tet(O) genes. Comparative genomic analysis identified identical erm(B) sequences among Campylobacter from turkeys, Streptococcus suis from pigs and Enterococcus faecium and Clostridium difficile from humans. This is consistent with multiple horizontal transfer events among different bacterial species colonizing turkeys. This example highlights the potential for dissemination of antimicrobial resistance across bacterial species boundaries which may compromise their effectiveness in antimicrobial therapy.

Detection of plasmid mediated colistin resistance (MCR-1) in Escherichia coli and Salmonella enterica isolated from poultry and swine in Spain.

Recent findings suggest that use of colistin as a last resort antibiotic is seriously threatened by the rise of a new plasmid mediated mechanism of resistance (MCR-1). This work identifies, for the first time in Southern Europe, the gene mcr-1 in nine strains from farm animals (poultry and swine) corresponding to five Escherichia coli and four Salmonella enterica, among which three belong to serovar Typhimurium and one to Rissen. The MCR-1 was found encoded by a plasmid highly mobilizable by conjugation to the E. coli J53 strain. Two E. coli strains carried two determinants, mcr-1 plus pmrA or pmrB mutations, known to confer colistin resistance.

Method comparison for enhanced recovery, isolation and qualitative detection of C. jejuni and C. coli from wastewater effluent samples.

Seeking a sensitive protocol, culture-dependent methods were compared to detect thermophilic Campylobacter species in untreated urban effluents. We evaluated various combinations of selective media, with and without an enrichment steps, as well as an extra filtration step. Culture-independent real-time quantitative PCR was also included and all detected isolates underwent antimicrobial susceptibility testing. All tested water samples contained Campylobacter DNA, but only 64% were positive after culture. Although enrichment using Preston broth resulted in better recovery of potentially stressed Campylobacter than Bolton or Campyfood broth (CFB), there was no significant increase in efficiency compared to direct plating. The type of selective agar media used, on the other hand, had a significant effect, with CASA plates performing better than mCCDA or CFA ones. Inclusion of an enrichment step increased the ratio of C. coli vs. C. jejuni being isolated. Resistances against all antimicrobials tested were observed in C. coli, but fewer instances of resistance were found in C. jejuni isolates. Whether this difference was the result of selection during the enrichment step could not be determined. The presence of Campylobacter in urban effluents can be considered as a valuable proxy for Campylobacter populations present in urban environments.