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The study investigates the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter coli in gastroenteritis patients in the eight most populous regions in Australia and compares the prevalence of antimicrobial resistance in Europe and North America. A total of 164 Campylobacter isolates were collected from patients with campylobacteriosis and tested for susceptibility to six antimicrobials using ETEST ® strips and compared with reports from Europe and the United States. Genomes were sequenced on Illumina NextSeq to identify genetic determinants of resistance. Phenotypically, 1.8%, 14.0%, 14.6%, and 20.1% of isolates were resistant to erythromycin (ERY), ampicillin, tetracycline (TET), and ciprofloxacin (CIP), respectively. Comparing published phenotypic results of antimicrobial resistance in several European countries and the United States with these Australian isolates reveals that rates observed in Australia are among the lowest observed for ERY, CIP, and TET for both C. coli and C. jejuni . For each antimicrobial tested, concordance between resistance phenotype and genotype ranged from 66.6% to 100.0%. This study highlights that, among industrialized countries, Portugal and Spain have very high levels of antimicrobial resistance in C. jejuni and C. coli , especially when compared with the United Kingdom, United States, and Australia.

Australian rates of campylobacteriosis are among the highest in developed countries, yet only limited work has been done to characterize Campylobacter spp. in Australian retail products. We performed whole genome sequencing (WGS) on 331 C. coli and 285 C. jejuni from retail chicken meat, as well as beef, chicken, lamb and pork offal (organs). Campylobacter isolates were highly diverse, with 113 sequence types (STs) including 38 novel STs, identified from 616 isolates. Genomic analysis suggests very low levels (2.3-15.3%) of resistance to aminoglycoside, beta-lactam, fluoroquinolone, macrolide and tetracycline antibiotics. A majority (>90%) of isolates (52/56) possessing the fluoroquinolone resistance-associated T86I mutation in the gyrA gene belonged to ST860, ST2083 or ST7323. The 44 pork offal isolates were highly diverse, representing 33 STs (11 novel STs) and harboured genes associated with resistance to aminoglycosides, lincosamides and macrolides not generally found in isolates from other sources. Prevalence of multidrug resistant genotypes was very low (<5%), but ten-fold higher in C. coli than C. jejuni. This study highlights that Campylobacter spp. from retail products in Australia are highly genotypically diverse and important differences in antimicrobial resistance exist between Campylobacter species and animal sources., Competing Interests: The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Author Names: Rhiannon L. Wallace, Dieter M. Bulach, Amy V. Jennison, Mary Valcanis, Angus McLure, James J. Smith, Trudy Graham, Themy Saputra, Simon Firestone, Sally Symes, Natasha Waters, Anastasia Stylianopoulos, Martyn D. Kirk, Kathryn Glass* AgriFutures is the only commercial entity that provided funding for this study. This does not alter our adherence to PLOS ONE policies on sharing data and materials. All other funding was from NHMRC and various government departments, all of which have now been mentioned in the funding statement.

The goal of this study was to follow ceftiofur-treated and untreated cattle in a normally functioning dairy to examine enteric Escherichia coli for changes in antibiotic resistance profiles and genetic diversity. Prior to treatment, all of the bacteria cultured from the cows were susceptible to ceftiofur. Ceftiofur-resistant E. coli was only isolated from treated cows during and immediately following the cessation of treatment, and the 12 bla(CMY-2)-positive isolates clustered into two genetic groups. E. coli bacterial counts dropped significantly in the treated animals (P < 0.027), reflecting a disappearance of the antibiotic-susceptible strains. The resistant bacterial population, however, did not increase in quantity within the treated cows; levels stayed low and were overtaken by a returning susceptible population. There was no difference in the genetic diversities of the E. coli between the treated and untreated cows prior to ceftiofur administration or after the susceptible population of E. coli returned in the treated cows. A cluster analysis of antibiotic susceptibility profiles resulted in six clusters, two of which were multidrug resistant and were comprised solely of isolates from the treated cows immediately following treatment. The antibiotic treatment provided a window to detect the presence of ceftiofur-resistant E. coli but did not appear to cause its emergence or result in its amplification. The finding of resistant isolates following antibiotic treatment is not sufficient to estimate the strength of selection pressure nor is it sufficient to demonstrate a causal link between antibiotic use and the emergence or amplification of resistance.

The suggestion that extraperitoneal cesarean section might be a useful method of preventing postoperative infectious complications prompted a prospective study of 91 primary extraperitoneal cesarean sections on afebrile laboring patients with ruptured membranes longer than 4 hours. Fifty of 91 patients having extraperitoneal cesarean sections (group A) were compared with 36 patients having low cervical transperitoneal primary cesarean sections (control group) meeting the same entry criteria in a prospective randomized fashion. The other 41 patients (group B = 25 of 41, group C = 16 of 41) were selected from qualifying high-risk patients depending on the availability of an experienced operator with group C receiving perioperative prophylactic antibiotics. The only significant difference in outcome was: four of 16 (25%) patients in group C (extraperitoneal cesarean section plus prophylactic antibiotics) developed postoperative endomyometritis versus 20 of 36 (56%), 28 of 50 (56%), and 12 of 25 (48%) patients in the transperitoneal primary cesarean section control group and extraperitoneal cesarean section group A and B, respectively (p less than 0.05). There was a trend toward enhanced postoperative recovery in all extraperitoneal cesarean section groups compared with the transperitoneal primary cesarean section control group. Thus, the technique of extraperitoneal cesarean section apparently offers no significant advantage in the prevention of postcesarean endomyometritis, but the use of perioperative prophylactic antibiotics apparently has significant impact.

The use of short-course (24-hour) prophylactic antibiotics was studied in 84 consecutive afebrile patients who underwent emergency primary cesarean section. There was a significant reduction in the incidence of postoperative endomyometritis in the group prophylactic antibiotics (12/45, 26.7%) compared to the control group not given prophylactic antibiotics (20/39, 51.3%), p less than 0.05. The duration of hospital stay was also significantly reduced by the use of prophylactic antibiotics (4.3 +/- 0.6 days versus 5.1 +/- 1.3 days, p less than 0.05). Other identified advantages that resulted from the use of prophylactic antibiotics included a shorter duration of treatment required for postoperative endomyometritis in the group given prophylactic antibiotics and an increased likelihood of being cured by initial therapy for endomyometritis in the group given prophylactic antibiotics (100% versus 70%). When taken together, these results indicate that the urgency of operation is a unique risk factor for postoperative infectious morbidity, and suggest that patients who undergo emergency primary cesarean section benefit from a short course of prophylactic antibiotics.