Colonisation of pet shop puppies with Brachyspira pilosicoli

Pathogen Detection and Resistome Analysis in Healthy Shelter Dogs Using Whole Metagenome Sequencing

According to the Humane Society, 25 to 40 percent of pet dogs in the United States are adopted from animal shelters. Shelter dogs can harbor bacterial, viral, fungal, and protozoal pathogens, posing risks to canine and human health. These bacterial pathogens may also carry antibiotic resistance genes (ARGs), serving as a reservoir for antimicrobial resistance (AMR) transmission. This study aimed to utilize whole metagenome sequencing (WMS) to screen for microbial pathogens and assess the resistome in healthy shelter dogs. Fecal samples from 58 healthy shelter dogs across 10 shelters in Kentucky, Tennessee, and Virginia were analyzed using WMS. Genomic DNA was extracted, and bioinformatics analyses were performed to identify pathogens and ARGs. The WMS detected 53 potentially zoonotic or known pathogens including thirty-eight bacterial species, two protozoa, five yeast species, one nematode, four molds, and three viruses. A total of 4560 ARGs signatures representing 182 unique genes across 14 antibiotic classes were detected. Tetracycline resistance genes were most abundant (49%), while β-lactam resistance genes showed the highest diversity with 75 unique ARGs. ARGs were predominantly detected in commensal bacteria; however, nearly half (18/38, 47.4%) of known bacterial pathogens detected in this study carried ARGs for resistance to one or more antibiotic classes. This study provides evidence that healthy shelter dogs carry a diverse range of zoonotic and antibiotic-resistant pathogens, posing a transmission risk through fecal shedding. These findings highlight the value of WMS for pathogen detection and AMR surveillance, informing therapeutic and prophylactic strategies to mitigate the transmission of pathogens among shelter dog populations and the risk associated with zoonoses.

Detection of Serum IgG Specific for Brachyspira pilosicoli and "Brachyspira canis" in Dogs

Brachyspira pilosicoli (B. pilosicoli) is a pathogen in pigs, poultry, and humans causing colitis, diarrhea, and poor growth rates. Its role as a canine pathogen is controversial, and the seroprevalence of specific IgG antibodies against B. pilosicoli in dogs is unknown. A further, not yet officially recognized Brachyspira species in dogs is "Brachyspira canis" ("B. canis"), which is proposed to be apathogenic. This study evaluates enzyme-linked immunosorbent assays (ELISAs) measuring serum IgG antibodies specific for B. pilosicoli or "B. canis" and investigates levels of specific IgG antibodies against B. pilosicoli and "B. canis" in a cohort of clinical patients presented at an animal referral clinic. These ELISAs use detergent-extracted antigens from B. pilosicoli and "B. canis". To increase analytic specificity, we precipitated the antigens with trichloroacetic acid (TCA) to isolate and concentrate the respective protein fraction. Our results indicate that a large number of serum IgG antibodies bind to shared epitopes of detergent-extracted antigens of the two spirochaetes. Our data also suggest that dogs might not only carry B. pilosicoli but also have "B. canis"-specific serum IgG antibodies.

Brachyspira in dogs: risk factors of shedding in central Germany and longitudinal study of an infected kennel

BACKGROUND

Brachyspira (B.) pilosicoli is a zoonotic pathogen, able to infect different animal species such as pigs, poultry, and rodents, causing intestinal spirochetosis. An association of gastrointestinal clinical signs, such as diarrhea, with the isolation of B. pilosicoli from fecal samples or rectal swabs has not been proven in dogs. Other Brachyspira species commonly isolated from dogs, such as "B. canis" and "B. pulli", are considered commensals. This study investigated the occurrence of different Brachyspira species in rectal swabs and fecal samples in an independent canine cohort in central Germany. These included samples from shelter dogs, hunting dogs, and dogs presenting at regional small animal practices with various clinical signs. Data about the dogs, including potential risk factors for Brachyspira isolation, were obtained using a standardized questionnaire. The study also longitudinally investigated a colony of Beagle dogs for Brachyspira over 5 years.

RESULTS

The rate of Brachyspira spp. isolation was 11% and included different Brachyspira species ("B. canis", "B. pulli", and B. pilosicoli). "B. canis" was detected in 18 dogs, whereas B. pilosicoli was only isolated from 1 dog in the independent cohort (not including the Beagle colony). Risk factors for shedding Brachyspira and "B. canis" were being less than 1 year of age and shelter origin. Gastrointestinal signs were not associated with the shedding of Brachyspira. B. pilosicoli and "B. canis" were isolated from several dogs of the same Beagle colony in 2017 and again in 2022, while Brachyspira was not isolated at multiple sampling time points in 2021.

CONCLUSIONS

Shedding of B. pilosicoli in dogs appears to be uncommon in central Germany, suggesting a low risk of zoonotic transmission from dogs. Commensal status of "B. canis" and "B. pulli" is supported by the results of this study. Findings from the longitudinal investigation of the Beagle colony agree with an asymptomatic long-term colonization of dogs with "B. canis" and B. pilosicoli and suggest that introducing new animals in a pack can trigger an increased shedding of B. pilosicoli.

Evidence of homologous recombination as a driver of diversity in Brachyspira pilosicoli

The enteric, pathogenic spirochaete Brachyspira pilosicoli colonizes and infects a variety of birds and mammals, including humans. However, there is a paucity of genomic data available for this organism. This study introduces 12 newly sequenced draft genome assemblies, boosting the cohort of examined isolates by fourfold and cataloguing the intraspecific genomic diversity of the organism more comprehensively. We used several in silico techniques to define a core genome of 1751 genes and qualitatively and quantitatively examined the intraspecific species boundary using phylogenetic analysis and average nucleotide identity, before contextualizing this diversity against other members of the genus Brachyspira. Our study revealed that an additional isolate that was unable to be species typed against any other Brachyspira lacked putative virulence factors present in all other isolates. Finally, we quantified that homologous recombination has as great an effect on the evolution of the core genome of the B. pilosicoli as random mutation (r/m=1.02). Comparative genomics has informed Brachyspira diversity, population structure, host specificity and virulence. The data presented here can be used to contribute to developing advanced screening methods, diagnostic assays and prophylactic vaccines against this zoonotic pathogen.

Polymerase chain reaction assay targeting nox gene for rapid identification of Brachyspira canis in dogs

Genus Brachyspira, as Gram negative anaerobic bacteria, colonize in dogs intestine. The aim of the current study was to determine the prevalence of Brachyspira spp. for the first time in Iran and rapid identification of Brachyspira spp. in dogs by a new designment of a species-specific primer set for B. canis. One hundred fifty-one fecal samples were obtained from dogs by rectal swab. Twenty dogs suffered from diarrhea and 131 of them were healthy. In 9.27% (14/151) of samples, spirochaetes were detected on primary cultures by weak hemolysis and positive Gram staining and then Brachyspira genus was confirmed by NADH oxidase (nox) gene via polymerase chain reaction. Among 14 isolates, twelve isolates were B. canis, one isolate was B. intermedia and another one was non-typeable. From 12 B. canis, only eight isolates were detected by designed specific primers. Ten Brachyspira spp. were isolated from dogs ≤ 1 year old (10/67, 14.92%) and 4 isolates were from > 1 year old dogs (4/84, 4.76%). The isolation rates from healthy and diarrheic dogs were (12/131, 9.16%) and (2/20, 10.00%), respectively. A statistically significant association was observed between the presence of Brachyspira spp. and the age under one year. Based on our findings, the nox gene in B. canis might have more sequence variability compared to other Brachyspira spp.

Severe Colitis with Portal Venous Gas Caused by Brachyspira pilosicoli Infection

We herein report a case of Brachyspira pilosicoli-caused severe colitis presenting with portal venous gas. A 75-year-old man was admitted because of a fever, severe abdominal pain and bloody diarrhea. He was negative for anti-HIV antibodies. He had been in close contact with a dog earlier. Abdominal computed tomography detected severe wall-thickening and fat-stranding of the entire colon accompanied by portal venous gas. A smear examination of his stool showed many Gram-negative spiral rods, suggesting intestinal spirochetosis. A polymerase chain reaction assay using stool samples detected an amplified band specific for B. pilosicoli. He responded well to antimicrobial agents including metronidazole.

The Spirochete Brachyspira pilosicoli, Enteric Pathogen of Animals and Humans

Brachyspira pilosicoli is a slow-growing anaerobic spirochete that colonizes the large intestine. Colonization occurs commonly in pigs and adult chickens, causing colitis/typhlitis, diarrhea, poor growth rates, and reduced production. Colonization of humans also is common in some populations (individuals living in village and peri-urban settings in developing countries, recent immigrants from developing countries, homosexual males, and HIV-positive patients), but the spirochete rarely is investigated as a potential human enteric pathogen. In part this is due to its slow growth and specialized growth requirements, meaning that it is not detectable in human fecal samples using routine diagnostic methods. Nevertheless, it has been identified histologically attached to the colon and rectum in patients with conditions such as chronic diarrhea, rectal bleeding, and/or nonspecific abdominal discomfort, and one survey of Australian Aboriginal children showed that colonization was significantly associated with failure to thrive. B. pilosicoli has been detected in the bloodstream of elderly patients or individuals with chronic conditions such as alcoholism and malignancies. This review describes the spirochete and associated diseases. It aims to encourage clinicians and clinical microbiologists to consider B. pilosicoli in their differential diagnoses and to develop and use appropriate diagnostic protocols to identify the spirochete in clinical specimens.

Healthy animals, healthy people: zoonosis risk from animal contact in pet shops, a systematic review of the literature

Background

Around 67 million pets are owned by households in the United Kingdom, and an increasing number of these are exotic animals. Approximately a third of pets are purchased through retail outlets or direct from breeders. A wide range of infections can be associated with companion animals.

Objectives

This study uses a systematic literature review to describe the transmission of zoonotic disease in humans associated with a pet shop or other location selling pets (incidents of rabies tracebacks and zoonoses from pet food were excluded).

Data sources

PubMed and EMBASE.

Results

Fifty seven separate case reports or incidents were described in the 82 papers that were identified by the systematic review. Summary information on each incident is included in this manuscript. The infections include bacterial, viral and fungal diseases and range in severity from mild to life threatening. Infections associated with birds and rodents were the most commonly reported. Over half of the reports describe incidents in the Americas, and three of these were outbreaks involving more than 50 cases. Many of the incidents identified relate to infections in pet shop employees.

Limitations

This review may have been subject to publication bias, where unusual and unexpected zoonotic infections may be over-represented in peer-reviewed publications. It was also restricted to English-language articles so that pathogens that are more common in non-Western countries, or in more exotic animals not common in Europe and the Americas, may have been under-represented.

Conclusions/implications

A wide spectrum of zoonotic infections are acquired from pet shops. Salmonellosis and psittacosis were the most commonly documented diseases, however more unusual infections such as tularemia also appeared in the review. Given their potential to spread zoonotic infection, it is important that pet shops act to minimise the risk as far as possible.

Faecal excretion of intestinal spirochaetes by urban dogs, and their pathogenicity in a chick model of intestinal spirochaetosis

This study aimed to obtain information about the types of spirochaetes colonising urban dogs in Thailand, and to investigate their pathogenic potential in a day-old chick model of intestinal spirochaetosis. Spirochaetes were isolated from the faeces of six of 47 (12.8%) healthy dogs and 11 of 104 (10.6%) dogs with diarrhoea. Their biochemical properties and 16S ribosomal DNA sequences were analysed. Four isolates were identified as Brachyspira pilosicoli, three resembled "Brachyspira pulli", nine clustered with "Brachyspira canis" and one was similar to Brachyspira intermedia. Canine isolates of B. pilosicoli, "B. canis" and "B. pulli", and control strains of Brachyspira hyodysenteriae, B. pilosicoli and Brachyspira innocens colonised experimentally infected day-old chicks. The chicks did not develop diarrhoea, but were significantly lighter than the non-infected group and those infected with B. innocens after 21 days (P<0.05). Using immunohistochemistry, spirochaetes were observed covering the surface epithelium and in the crypts of chicks in all three groups challenged with the canine isolates. Variable histopathological changes were seen, with the greatest inflammatory cell infiltration into the lamina propria occurring in the group infected with "B. pulli". Canine "B. canis", "B. pulli" and B. pilosicoli isolates may have pathogenic potential.

Isolation and Characterization of Brachyspira spp. from Dogs in the Czech Republic

The objectives of this study were to establish the prevalence of intestinal Spirochetes of the genusBrachyspirain Czech dogs and to determine the susceptibility of obtainedB. pilosicoliisolates to selected antibacterial substances. Spirochetes were diagnosed microscopically in 23 out of 1139 samples of dogs’ excrements, primarily intended for a parasitological testing. The cultivation of positive samples provided 10 brachyspira isolates, which were, on the basis of their biochemical activity and the results of the species-specific PCR, identified asB. pilosicoli(9 isolates) andB. hyodysenteriae(1 isolate). These dogs came from households. All the 7 tested isolatesB. pilosicoliwere sensitive to metronidazole and doxycycline, uniformly resistant to erythromycin, partly sensitive to cefazoline, lincomicine and ampicilline except for one isolate ofB. pilosicoli, which was resistant to ampicilline. The second part of study was focused on dogs with diarrhoea that came from animal shelters, where a high prevalence of 58% (10/17) ofB. pilosicoliwas found.

Prevalence of Brachyspira pilosicoli and "Brachyspira canis" in dogs and their association with diarrhoea

The aims of this study were to investigate the prevalence of colonization with intestinal spirochaetes in dogs, and to assess their association with diarrhoea. To achieve this, faecal samples from 311 dogs were obtained between November 2008 and April 2009 and cultured for Brachyspira species. A total of 41 Brachyspira spp. isolates were recovered, and these were classified into species according to their biochemical properties, and results of a B. pilosicoli species-specific PCR, and partial amplification of the nox gene with sequencing of the product. An overall Brachyspira spp. prevalence of 13.2% (41/311) was obtained. The prevalence of Brachyspira pilosicoli faecal shedding was 4.8% (15/311) while "Brachyspira canis" was identified in 8.0% (25/311) of the sampled dogs. One dog shed an isolate tentatively identified as B. intermedia. A statistically significant association between the shedding of B. pilosicoli and the presence of diarrhoea in dogs was demonstrated (P<0.001). Risk factors for shedding of Brachyspira spp. were investigated. Using the odds ratio, the risk of B. pilosicoli shedding was five times higher among dogs up to 1 year of age as compared with adult dogs (older than 1 year). These findings may have practical implications in the public and animal health fields.

Colonic spirochetosis in animals and humans

Colonic spirochetosis is a disease caused by the gram-negative bacteria Brachyspira aalborgi and Brachyspira pilosicoli. B. pilosicoli induces disease in both humans and animals, whereas B. aalborgi affects only humans and higher primates. Symptoms in humans include diarrhea, rectal bleeding, and abdominal cramps. Colonic spirochetosis is common in third world countries; however, in developed countries, the disease is observed mainly in homosexual males. Terminally ill patients infected with Brachyspira are particularly at risk for developing spirochetemia. Diarrhea, poor growth performance, and decreased feed-to-gain efficiency is seen in pigs with colonic spirochetosis. The disease in chickens is characterized by delayed and/or reduced egg production, diarrhea, poor feed conversion, and retarded growth. Thus, colonic spirochetosis can represent a serious economic loss in the swine and poultry industries. The organisms are transmitted by the fecal-oral route, and several studies have demonstrated that human, primate, pig, dog, or bird strains of B. pilosicoli can be transmitted to pigs, chickens, and mice. B. pilosicoli may be a zoonotic pathogen, and although it has not been demonstrated, there is a possibility that both B. pilosicoli and B. aalborgi can be transferred to humans via contact with the feces of infected animals, meat from infected animals, or food contaminated by food handlers. Neither B. pilosicoli nor B. aalborgi has been well characterized in terms of basic cellular functions, pathogenicity, or genetics. Studies are needed to more thoroughly understand these Brachyspira species and their disease mechanisms.

Molecular and ultrastructural characterization of porcine hippurate-negative Brachyspira pilosicoli

Brachyspira pilosicoli, the causative agent of porcine intestinal spirochetosis, usually has hippurate-cleaving capacity. We have regularly isolated hippurate-negative B. pilosicoli from cases of porcine diarrhea. In this study, we show that these biochemically atypical B. pilosicoli isolates can be classified as B. pilosicoli. 16S ribosomal DNA was partially sequenced from eight hippurate-negative and two hippurate-positive B. pilosicoli-like isolates from seven herds. The differences in nucleotide sequence with B. pilosicoli P43/6/78 type strain were not associated with hippurate cleavage. In 877 bp, the hippurate-negative isolates had a similarity of 98.63 to 100% to the type strain, with the corresponding figures for the two hippurate-positive isolates being 98.86 and 100%. The nucleotide sequences of hippurate-positive isolates were identical to the respective sequences of hippurate-negative isolates from one herd. The DNA macrorestriction patterns of a total of 20 hippurate-negative and -positive B. pilosicoli isolates were diverse, and no clustering in conjunction with the hippurate reaction was found. In two herds, hippurate-positive and -negative B. pilosicoli isolates had a common macrorestriction pattern. The ultrastructure of hippurate-negative isolates was similar to the type strain. In conclusion, B. pilosicoli can be either hippurate positive or negative and, thus, the scheme for biochemical differentiation of porcine Brachyspira should be revised to include identification of hippurate-negative B. pilosicoli.

Brachyspira pilosicoli isolated from pigs in Japan

Two of four weak beta-hemolytic isolates of intestinal spirochetes isolated from pigs in Japan possessed a unique base alignment of TTTTTT on the 16S ribosomal DNA of Brachyspira pilosicoli and were identified as B. pilosicoli. The other two isolates were not identified by this technique. The identified isolates were 4.2 to 11 microm in length and 0.2 to 0.3 microm in diameter, 4 periplasmic flagella at each end were observed dominantly. The isolates were hippurate positive but indole negative. This is the first report on the isolation of B. pilosicoli from pigs in Japan.

Brachyspira pilosicoli isolated from two beagles and one mongrel in Japan

The feces, colonic contents, and colonic mucosa from two beagles and a mongrel with and without mucohemorrhagic diarrhea were anaerobically cultured and after 72 hr, lucent and rough colonies with weak beta-hemolysis were observed. Small spirochetes with one or two loose waves in the colonies were observed under a phase contrast microscope and the spirochete cells sometimes aggregated. The 16SrDNA sequencing results demonstrated that the canine isolates were B. pilosicoli and the base alignments registered in DDBJ. This is the first report concerning the isolation of B. pilosicoli from dogs in Japan.

Optimal fecal assessment

Fecal testing is a common component of most gastrointestinal work-ups. A multitude of diagnostic techniques are available for identifying parasites and pathogens, or showing abnormalities of flora. Optimal fecal assessment involves careful formulation of a differential list based on signalment, history, and clinical signs. Tests should be selected and interpreted based on their relative sensitivity and specificity for specific conditions. It is essential to use effective testing methods for the etiologies of concern. This article reviews the plethora of diagnostic techniques available for fecal assessment. Indications, limitations, and issues of specimen handling for each technique are discussed. The optimal approach to the diagnosis of some common parasites, pathogens, abnormalities of flora, and metabolic conditions are covered.