Campylobacter in cattle: molecular epidemiology and antibiotic resistance

Ruminant Campylobacter, (C. jejuni and C. coli), contributes significantly to foodborne illnesses in humans. A recently emerged C. jejuni clone (named SA) is also a major cause of ruminant abortion in the United States. Despite the importance of Campylobacter in ruminant health and food safety, little is known about its prevalence and antibiotic resistance profiles in cattle production systems in the U.S. In this project, we examined the antibiotic resistance susceptibility and mechanisms of the Campylobacter isolates derived from 35 feedlot cattle farms in 5 different states, and determined the distribution of C. jejuni clone SA in the feedlots and in dairy cows by using isolates collected by NAHMS Dairy Studies 2002, 2007 and 2014. In feedlot cattle, clone SA accounted for 5.8% of the total C. jejuni isolates, but prevalence varied from farm to farm. In dairy cattle, the overall prevalence of clone SA was 7.2%, and a declining trend in the prevalence was detected from 2002 to 2014. Whole genome sequence analyses of the dairy isolates revealed the high genomic stability of clone SA over the years. The results also revealed high prevalence of fluoroquinolone (FQ) resistance in the feedlot cattle isolates. Molecular typing revealed that clonal expansion was involved in dissemination of FQ-resistant C. coli. Notably, florfenicol resistance, which was historically low in Campylobacter, also emerged in the bovine Campylobacter isolates. Whole genome sequencing analysis identified a novel cfr variant, named cfr(C), in the florfenicol-resistant isolates. Cloning of cfr (C) and conjugative transfer of the cfr (C)-containing plasmid confirmed its role in conferring resistance to multiple classes of antibiotics including phenicols, lincosamides, pleuromutilins, and oxazolidinones. The cfr(C) gene was detected in 10% of the C. coli isolates, and molecular typing revealed its spread mainly via clonal expansion. These findings reveal the common presence of C. jejuni clone SA in both beef and dairy cattle and the rising prevalence of FQ-resistant Campylobacter as well as the emergence of a novel multidrug resistant mechanism Cfr(C) in ruminant Campylobacter in the U.S. These results provide new insights into the epidemiology and antibiotic resistance of Campylobacter in the bovine reservoir

A mutator phenotype promoting the emergence of spontaneous oxidative stress-resistant mutants in Campylobacter jejuni

Campylobacter jejuni is a leading cause of foodborne illnesses worldwide. As a microaerophilic organism, C. jejuni must be able to defend against oxidative stress encountered both in the host and in the environment. How Campylobacter utilizes a mutation-based mechanism for adaptation to oxidative stress is still unknown. Here we present a previously undescribed phenotypic and genetic mechanism that promotes the emergence of oxidative stress resistant mutants. Specifically, we showed that a naturally occurring mutator phenotype, resulting from a loss of function mutation in the DNA repair enzyme MutY, increased oxidative stress resistance (OXR) in C. jejuni. We further demonstrated that MutY malfunction didn\u27t directly contribute to the OXR phenotype, but increased the spontaneous mutation rate in the peroxide regulator gene perR, which functions as a repressor for multiple genes involved in oxidative stress resistance. Mutations in PerR resulted in loss of its DNA binding function and derepression of PerR-controlled oxidative stress defense genes, thereby conferring an OXR phenotype and facilitating Campylobacter survival under oxidative stress. These findings reveal a new mechanism that promotes the emergence of spontaneous OXR mutants in bacterial organisms

Practical m

In collaborative data publishing (CDP), an m-adversary attack refers to a scenario where up to m malicious data providers collude to infer data records contributed by other providers. Existing solutions either rely on a trusted third party (TTP) or introduce expensive computation and communication overheads. In this paper, we present a practical distributed k-anonymization scheme, m-k-anonymization, designed to defend against m-adversary attacks without relying on any TTPs. We then prove its security in the semihonest adversary model and demonstrate how an extension of the scheme can also be proven secure in a stronger adversary model. We also evaluate its efficiency using a commonly used dataset

Adult image detection combining bovw based on region of interest and color moments

Abstract. To prevent pornography from spreading on the Internet effectively, we propose a novel method of adult image detection which combines bag-ofvisual-words (BoVW) based on region of interest (ROI) and color moments (CM). The goal of BoVW is to automatically mine the local patterns of adult contents, called visual words. The usual BoVW method clusters visual words from the patches in the whole image and adopts the weighting schemes of hard assignment. However, there are many background noises in the whole image and soft-weighting scheme is better than hard assignment. Therefore, we propose the method of BoVW based on ROI, which includes two perspectives. Firstly, we propose to create visual words in ROI for adult image detection. The representative power of visual words can be improved because the patches in ROI are more indicative to adult contents than those in the whole image. Secondly, soft-weighting scheme is adopted to detect adult images. Moreover, CM is selected by evaluating some commonly-used global features to be combined with BoVW based on ROI. The experiments and the comparison with the state-of-the-art methods show that our method is able to remarkably improve the performance of adult image detection

Evaluation of a village-based digital health kiosks program: A protocol for a cluster randomized clinical trial

Background To address disparities in healthcare quality and access between rural and urban areas in China, reforms emphasize strengthening primary care and digital health utilization. Yet, evidence on digital health approaches in rural areas is lacking. Objective This study will evaluate the effectiveness of Guangdong Second Provincial General Hospital's Digital Health Kiosk program, which uses the Dingbei telemedicine platform to connect rural clinicians to physicians in upper-level health facilities and provide access to artificial intelligence-enabled diagnostic support. We hypothesize that our interventions will increase healthcare utilization and patient satisfaction, decrease out-of-pocket costs, and improve health outcomes. Methods This cluster randomized control trial will enroll clinics according to a partial factorial design. Clinics will be randomized to either a control arm with clinician medical training, a second arm additionally receiving Dingbei telemedicine training, or a third arm with monetary incentives for patient visits conducted through Dingbei plus all prior interventions. Clinics in the second and third arm will then be orthogonally randomized to a social marketing arm that targets villager awareness of the kiosk program. We will use surveys and Dingbei administrative data to evaluate clinic utilization, revenue, and clinician competency, as well as patient satisfaction and expenses. Results We have received ethical approval from Guangdong Second Provincial General Hospital (IRB approval number: GD2H-KY IRB-AF-SC.07-01.1), Peking University (IRB00001052-21007), and the University of North Carolina at Chapel Hill (323385). Study enrollment began April 2022. Conclusions This study has the potential to inform future telemedicine approaches and assess telemedicine as a method to address disparities in healthcare access. Trial registration number: ChiCTR210005387

Key Role of Capsular Polysaccharide in the Induction of Systemic Infection and Abortion by Hypervirulent Campylobacter jejuni

Campylobacter jejuni is a zoonotic pathogen, and a hypervirulent clone, named clone SA, has recently emerged as the predominant cause of ovine abortion in the United States. To induce abortion, orally ingested Campylobacter must translocate across the intestinal epithelium, spread systemically in the circulation, and reach the fetoplacental tissue. Bacterial factors involved in these steps are not well understood. C. jejuni is known to produce capsular polysaccharide (CPS), but the specific role that CPS plays in systemic infection and particularly abortion in animals remains to be determined. In this study, we evaluated the role of CPS in bacteremia using a mouse model and in abortion using a pregnant guinea pig model following oral challenge. Compared with C. jejuni NCTC 11168 and 81-176, a clone SA isolate (IA3902) resulted in significantly higher bacterial counts and a significantly longer duration of bacteremia in mice. The loss of capsule production via gene-specific mutagenesis in IA3902 led to the complete abolishment of bacteremia in mice and abortion in pregnant guinea pigs, while complementation of capsule expression almost fully restored these phenotypes. The capsule mutant strain was also impaired for survival in guinea pig sera and sheep blood. Sequence-based analyses revealed that clone SA possesses a unique CPS locus with a mosaic structure, which has been stably maintained in all clone SA isolates derived from various hosts and times. These findings establish CPS as a key virulence factor for the induction of systemic infection and abortion in pregnant animals and provide a viable candidate for the development of vaccines against hypervirulent C. jejuni

Low escape-rate genome safeguards with minimal molecular perturbation of Saccharomyces cerevisiae

As the use of synthetic biology both in industry and in academia grows, there is an increasing need to ensure biocontainment. There is growing interest in engineering bacterial- and yeast-based safeguard (SG) strains. First-generation SGs were based on metabolic auxotrophy; however, the risk of cross-feeding and the cost of growth-controlling nutrients led researchers to look for other avenues. Recent strategies include bacteria engineered to be dependent on nonnatural amino acids and yeast SG strains that have both transcriptional- and recombinational-based biocontainment. We describe improving yeast Saccharomyces cerevisiae-based transcriptional SG strains, which have near-WT fitness, the lowest possible escape rate, and nanomolar ligands controlling growth. We screened a library of essential genes, as well as the best-performing promoter and terminators, yielding the best SG strains in yeast. The best constructs were fine-tuned, resulting in two tightly controlled inducible systems. In addition, for potential use in the prevention of industrial espionage, we screened an array of possible "decoy molecules" that can be used to mask any proprietary supplement to the SG strain, with minimal effect on strain fitness