Genotyping and antibiotic resistance patterns of Campylobacter fetus subsp.venerealis from cattle farms in India

Biochemical and molecular characterization of Campylobacter fetus isolates from bulls subjected to bovine genital campylobacteriosis diagnosis in Spain

BACKGROUND

Bovine genital campylobacteriosis (BGC) is caused by Campylobacter fetus subsp. venerealis (Cfv) including its biovar intermedius (Cfvi). This sexually transmitted disease induces early reproductive failure causing considerable economic losses in the cattle industry. Using a collection of well-characterized isolates (n = 13), C. fetus field isolates (n = 64) and saprophytic isolates resembling Campylobacter (n = 75) obtained from smegma samples of breeding bulls, this study evaluated the concordance of the most used phenotypic (H2S production in cysteine medium and 1% glycine tolerance) and molecular (PCR) methods for the diagnosis of BGC and assessed possible cross-reactions in the molecular diagnostic methods.

RESULTS

Characterization at the subspecies level (fetus vs. venerealis) of C. fetus isolated from bull preputial samples using phenotypic and molecular (PCR targeting nahE and ISCfe1) methods showed moderate concordance (κ = 0.462; CI: 0.256-0.669). No cross-reactions were observed with other saprophytic microaerophilic species or with other Campylobacter species that can be present in preputial samples. Whole genome sequencing (WGS) of discrepant isolates showed 100% agreement with PCR identification. For the differentiation of Cfv biovars, comparison of the H2S test (at 72 h and 5 days of incubation) and a PCR targeting the L-cysteine transporter genes showed higher concordance when H2S production was assessed after 5 days (72 h; κ = 0.553, 0.329-0.778 CI vs. 5 days; κ = 0.881, 0.631-1 CI), evidencing the efficacy of a longer incubation time.

CONCLUSIONS

This study confirmed the limitations of biochemical tests to correctly identify C. fetus subspecies and biovars. However, in the case of biovars, when extended incubation times for the H2S test (5 days) were used, phenotypic identification results were significantly improved, although PCR-based methods produced more accurate results. Perfect agreement of WGS with the PCR results and absence of cross-reactions with non-C. fetus saprophytic bacteria from the smegma demonstrated the usefulness of these methods. Nevertheless, the identification of new C. fetus subspecies-specific genes would help to improve BGC diagnosis.

One Health: a holistic approach for food safety in livestock

The food safety of livestock is a critical issue between animals and humans due to their complex interactions. Pathogens have the potential to spread at every stage of the animal food handling process, including breeding, processing, packaging, storage, transportation, marketing and consumption. In addition, application of the antibiotic usage in domestic animals is a controversial issue because, while they can combat food-borne zoonotic pathogens and promote animal growth and productivity, they can also lead to the transmission of antibiotic-resistant microorganisms and antibiotic-resistant genes across species and habitats. Coevolution of microbiomes may occur in humans and animals as well which may alter the structure of the human microbiome through animal food consumption. One Health is a holistic approach to systematically understand the complex relationships among humans, animals and environments which may provide effective countermeasures to solve food safety problems aforementioned. This paper depicts the main pathogen spectrum of livestock and animal products, summarizes the flow of antibiotic-resistant bacteria and genes between humans and livestock along the food-chain production, and the correlation of their microbiome is reviewed as well to advocate for deeper interdisciplinary communication and collaboration among researchers in medicine, epidemiology, veterinary medicine and ecology to promote One Health approaches to address the global food safety challenges.

Investigation of Campylobacter fetus in breeding bulls of private farms in Bangladesh

BACKGROUND

Bovine genital campylobacteriosis (BGC) is a venereal disease caused by Campylobacter fetus that has a negative impact on animal reproduction. The bull is considered to be a symptomless carrier that spreads the disease agent to breeding cows, causing infertility and sporadic abortion.

AIM

The study aims to estimate the prevalence, identify risk factors of Campylobacter fetus (C. fetus) infection and antimicrobial resistance pattern of the C. fetus isolates.

METHOD

A cross-sectional survey was conducted in Mymensingh district of Bangladesh. Bull smegma samples (single sample from each bull) were collected from 300 bulls from four farms and tested via culture, biochemical identification and finally 16S rRNA and cdtA gene-based molecular assays (PCR) for herd and animal-level prevalence estimation. Herd- and animal-level data on risk factors were collected from the farmers using a pretested questionnaire and analysed by univariable and multivariable logistic regression models with a p value of <0.05 was taken statistically significant for both analyses.

RESULTS

Among the surveyed farms, 75% (95% CI: 19.4%-99.4%) were confirmed to have bulls infected with Campylobacter fetus at herd level. However, animal-level occurrence of C. fetus was estimated to be 8.7% (26/300) (95% CI: 5.7%-12.4%). Natural service increases the odds of campylobacteriosis 38.18 times (95% CI: 13.89-104.94) in comparison to artificial insemination for C. fetus infection in bulls. Significantly, half of the isolates (50%, n = 13) were identified to be multidrug resistant (MDR) for three to five antimicrobial agents.

CONCLUSION

This study highlights the need to develop official guidelines for C. fetus control and prevention in Bangladesh including mandatory artificial insemination in reproductive cows and heifers, routine screening of breeding bulls for C. fetus free status.

Characterization of Brucella spp. and other abortigenic pathogens from aborted tissues of cattle and goats in Rwanda

Background

Abortions cause tremendous economic losses in food‐producing animals and may lead to food insecurity.

Objectives

This study aimed to characterize Brucella spp. and other abortigenic pathogens from aborted tissues of cattle.

Methods

For cattle, aborted tissues (n = 19) were cultured, and Brucella spp. were detected using the genus‐specific 16S‐23S ribosomal DNA interspacer region (ITS) assay and speciated using Brucella abortus, Brucella melitensis, Brucella ovis, and Brucella suis (AMOS) and Bruce‐ladder PCR assays. Brucella negative samples were screened using the eight abortigenic pathogens PCR panel. Samples from an abortion outbreak that occurred within a goat tribe were included in this investigation. Sera of females (n = 8) and males (n = 2) were analyzed using the Rose Bengal Test (RBT) and indirect enzyme‐linked immunosorbent assay (i‐ELISA), while vaginal swabs (n = 3) and aborted tissues (n = 1) were cultured and characterized.

Results

The ITS‐PCR detected Brucella DNA in cultures from two aborted tissues of cattle (10.5%, [2/19]), which were identified as B. melitensis (n = 1), and B. abortus (n = 1) using AMOS and Bruce‐ladder PCR assays. Campylobacter fetus (n = 7) and Leptospira spp. (n = 4) including co‐infections (n = 2) of C. fetus and Leptospira spp. were identified from the Brucella negative samples of cattle. Goats (100.0%, 10/10) were brucellosis seropositive on RBT and i‐ELISA. Mixed infections caused by B. melitensis and B. abortus were isolated from the vaginal swabs (n = 3) and aborted tissues (n = 1).

Discussion and conclusions

This is the first identification of abortion‐associated pathogens in aborted cattle indicating the enormous financial losses and a threat to public health. It is therefore essential to include these identified pathogens in the surveillance scheme of veterinary and human services.