Expanded multilocus sequence typing and comparative genomic hybridization of Campylobacter coli isolates from multiple hosts.

The purpose of this work was to evaluate the evolutionary history of Campylobacter coli isolates derived from multiple host sources and to use microarray comparative genomic hybridization to assess whether there are particular genes comprising the dispensable portion of the genome that are more commonly associated with certain host species. Genotyping and ClonalFrame analyses of an expanded 16-gene multilocus sequence typing (MLST) data set involving 85 isolates from 4 different hosts species tentatively supported the development of C. coli host-preferred groups and suggested that recombination has played various roles in their diversification; however, geography could not be excluded as a contributing factor underlying the history of some of the groups. Population genetic analyses of the C. coli pubMLST database by use of STRUCTURE suggested that isolates from swine form a relatively homogeneous genetic group, that chicken and human isolates show considerable genetic overlap, that isolates from ducks and wild birds have similarity with environmental water samples and that turkey isolates have a connection with human infection similar to that observed for chickens. Analysis of molecular variance (AMOVA) was performed on these same data and suggested that host species was a significant factor in explaining genetic variation and that macrogeography (North America, Europe, and the United Kingdom) was not. The microarray comparative genomic hybridization data suggested that there were combinations of genes more commonly associated with isolates derived from particular hosts and, combined with the results on evolutionary history, suggest that this is due to a combination of common ancestry in some cases and lateral gene transfer in others.

Prevalence and antimicrobial resistance of thermophilic Campylobacter spp. from cattle farms in Washington State.

The prevalence of thermophilic Campylobacter spp. was investigated in cattle on Washington State farms. A total of 350 thermophilic Campylobacter isolates were isolated from 686 cattle sampled on 15 farms (eight dairies, two calf rearer farms, two feedlots, and three beef cow-calf ranches). Isolate species were identified with a combination of phenotypic tests, hipO colony blot hybridization, and multiplex lpxA PCR. Breakpoint resistance to four antimicrobials (ciprofloxacin, nalidixic acid, erythromycin, and doxycycline) was determined by agar dilution. Campylobacter jejuni was the most frequent species isolated (34.1%), followed by Campylobacter coli (7.7%) and other thermophilic campylobacters (1.5%). The most frequently detected resistance was to doxycycline (42.3% of 350 isolates). Isolates from calf rearer facilities were more frequently doxycycline resistant than isolates from other farm types. C. jejuni was most frequently susceptible to all four of the antimicrobial drugs studied (58.8% of 272 isolates). C. coli isolates were more frequently resistant than C. jejuni, including resistance to quinolone antimicrobials (89.3% of isolates obtained from calves on calf rearer farms) and to erythromycin (72.2% of isolates obtained from feedlot cattle). Multiple drug resistance was more frequent in C. coli (51.5%) than in C. jejuni (5.1%). The results of this study demonstrate that C. jejuni is widely distributed among Washington cattle farms, while C. coli is more narrowly distributed but significantly more resistant.

Increasing prevalence of Campylobacter jejuni in feedlot cattle through the feeding period.

The prevalence of Campylobacter jejuni in commercial feedlot cattle was monitored throughout the feeding period by repeated bacteriologic culture of feces. Fecal pats (n = 10) in 20 feedlot pens were sampled at 2-weeks interval beginning at entry into the feedlot and continuing until slaughter. The least-squares mean C. jejuni prevalence increased from 1.6% at the first sampling to 61.3% at the final sampling just prior to slaughter. Diverse C. jejuni pulsed-field gel electrophoresis macrorestriction profiles (MRP) were identified among the cattle isolates, but five prevalent MRP and minor variants accounted for >80% of all typed isolates. Chlorination of the water supplied to the water troughs of half of the pens did not affect C. jejuni prevalence in the cattle. Overall, the least-squares mean C. jejuni prevalences were 45.6 and 43.6% in chlorinated and nonchlorinated feedlot pens, respectively. The results of this study demonstrate apparent transmission of C. jejuni among feedlot cattle during the feeding period, unaffected by water chlorination, resulting in a high prevalence of C. jejuni excretion by cattle approaching slaughter.