Evaluating rectal swab collection method for gut microbiome analysis in the common marmoset (Callithrix jacchus)

Are fecal samples an appropriate proxy for amphibian intestinal microbiota?

The intestinal microbiota, an invisible organ supporting a host's survival, has essential roles in metabolism, immunity, growth, and development. Since intestinal microbiota influences a host's biology, application of such data to wildlife conservation has gained interest. There are standard protocols for studying the human intestinal microbiota, but no equivalent for wildlife. A major challenge is sampling the intestinal microbiota in an effective, unbiased way. Fecal samples are a popular proxy for intestinal microbiota because collection is non-invasive and allows for longitudinal sampling. Yet it is unclear whether the fecal microbiota is representative of the intestinal microbiota. In wildlife studies, research on the sampling methodology is limited. In this study focusing on amphibians, we characterize and compare the microbiota (small intestine, large intestine, and feces) of two Hong Kong stream-dwelling frog species: Lesser Spiny Frog (Quasipaa exilispinosa) and Hong Kong Cascade Frog (Amolops hongkongensis). We found that the microbiota of both species are similar at the level of phylum and family, but diverge at the level of genus. When we assessed the performance of fecal microbiota in representing the intestinal microbiota in these two species, we found that (1) the microbiota of the small and large intestine differs significantly, (2) feces are not an appropriate proxy of either intestinal sections, and (3) a set of microbial taxa significantly differs between sample types. Our findings raise caution equating fecal and intestinal microbiota in stream-dwelling frogs. Sampling feces can avoid sacrifice of an animal, but researchers should avoid over-extrapolation and interpret results carefully.

Effects of enhanced insect feeding on the faecal microbiota and transcriptome of a family of captive common marmosets (Callithrix jacchus)

Common marmosets have been widely used in biomedical research for years. Nutritional control is an important factor in managing their health, and insect intake would be beneficial for that purpose because common marmosets frequently feed on insects in natural habitats. Here, we examined the effect of enhanced insect feeding on the gut by analysing the faecal microbiota and transcripts of captive marmosets. A family consisting of six marmosets was divided into two groups. During the seven-day intervention period, one group (the insect feeding group, or Group IF) was fed one cricket and one giant mealworm per marmoset per day, while the other (the control group, or Group C) was not fed these insects. RNA was extracted from faecal samples to evaluate the ecology and transcripts of the microbiota, which were then compared among time points before (Pre), immediately after (Post), and two weeks after the intervention (Follow_up) using total RNA sequencing. The gut microbiota of marmosets showed Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria as dominant phyla. Linear discriminant analysis showed differential characteristics of microbiota with and without insect feeding treatment. Further analysis of differentially expressed genes revealed increases and decreases in Bacteroidetes and Firmicutes, respectively, corresponding to the availability of insects under both Post and Follow_up conditions. Significant changes specific to insect feeding were also detected within the transcriptome, some of which were synchronized with the fluctuations in the microbiota, suggesting a functional correlation or interaction between the two. The rapid changes in the microbiota and transcripts may be achieved by the microbiota community originally developed in the wild through marmosets' feeding ecology. The results were informative for identifying the physiological impact of insect feeding to produce a better food regimen and for detecting transcripts that are currently unidentifiable.

Alterations in common marmoset gut microbiome associated with duodenal strictures

Chronic gastrointestinal (GI) diseases are the most common diseases in captive common marmosets (Callithrix jacchus). Despite standardized housing, diet and husbandry, a recently described gastrointestinal syndrome characterized by duodenal ulcers and strictures was observed in a subset of marmosets sourced from the New England Primate Research Center. As changes in the gut microbiome have been associated with GI diseases, the gut microbiome of 52 healthy, non-stricture marmosets (153 samples) were compared to the gut microbiome of 21 captive marmosets diagnosed with a duodenal ulcer/stricture (57 samples). No significant changes were observed using alpha diversity metrics, and while the community structure was significantly different when comparing beta diversity between healthy and stricture cases, the results were inconclusive due to differences observed in the dispersion of both datasets. Differences in the abundance of individual taxa using ANCOM, as stricture-associated dysbiosis was characterized by Anaerobiospirillum loss and Clostridium perfringens increases. To identify microbial and serum biomarkers that could help classify stricture cases, we developed models using machine learning algorithms (random forest, classification and regression trees, support vector machines and k-nearest neighbors) to classify microbiome, serum chemistry or complete blood count (CBC) data. Random forest (RF) models were the most accurate models and correctly classified strictures using either 9 ASVs (amplicon sequence variants), 4 serum chemistry tests or 6 CBC tests. Based on the RF model and ANCOM results, C. perfringens was identified as a potential causative agent associated with the development of strictures. Clostridium perfringens was also isolated by microbiological culture in 4 of 9 duodenum samples from marmosets with histologically confirmed strictures. Due to the enrichment of C. perfringens in situ, we analyzed frozen duodenal tissues using both 16S microbiome profiling and RNAseq. Microbiome analysis of the duodenal tissues of 29 marmosets from the MIT colony confirmed an increased abundance of Clostridium in stricture cases. Comparison of the duodenal gene expression from stricture and non-stricture marmosets found enrichment of genes associated with intestinal absorption, and lipid metabolism, localization, and transport in stricture cases. Using machine learning, we identified increased abundance of C. perfringens, as a potential causative agent of GI disease and intestinal strictures in marmosets.

Analysis of gut microbiome profiles in common marmosets (Callithrix jacchus) in health and intestinal disease

Chronic gastrointestinal (GI) diseases are the most common diseases in captive common marmosets. To understand the role of the microbiome in GI diseases, we characterized the gut microbiome of 91 healthy marmosets (303 samples) and 59 marmosets diagnosed with inflammatory bowel disease (IBD) (200 samples). Healthy marmosets exhibited "humanized," Bacteroidetes-dominant microbiomes. After up to 2 years of standardized diet, housing and husbandry, marmoset microbiomes could be classified into four distinct marmoset sources based on Prevotella and Bacteroides levels. Using a random forest (RF) model, marmosets were classified by source with an accuracy of 93% with 100% sensitivity and 95% specificity using abundance data from 4 Prevotellaceae amplicon sequence variants (ASVs), as well as single ASVs from Coprobacter, Parabacteroides, Paraprevotella, Phascolarctobacterium, Oribacterium and Fusobacterium. A single dysbiotic IBD state was not found across all marmoset sources, but IBD was associated with lower alpha diversity and a lower Bacteroides:Prevotella copri ratio within each source. IBD was highest in a Prevotella-dominant cohort, and consistent with Prevotella-linked diseases, pro-inflammatory genes in the jejunum were upregulated. RF analysis of serum biomarkers identified serum calcium, hemoglobin and red blood cell (RBC) counts as potential biomarkers for marmoset IBD. This study characterizes the microbiome of healthy captive common marmosets and demonstrates that source-specific microbiomes can be retained despite standardized diets and husbandry practices. Marmosets with IBD had decreased alpha diversity and a shift in the ratio of Bacteroides:Prevotella copri compared to healthy marmosets.

Fecal bacterial communities of wild black capuchin monkeys (Sapajus nigritus) from the Atlantic Forest biome in Southern Brazil are divergent from those of other non-human primates

Gut microbiota are influenced by factors such as diet, habitat, and social contact, which directly affect the host's health. Studies related to gut microbiota in non-human primates are increasing worldwide. However, little remains known about the gut bacterial composition in wild Brazilian monkeys. Therefore, we studied the fecal microbiota composition of wild black capuchin monkey (Sapajus nigritus) (n=10) populations from two different Atlantic Forest biome fragments (five individuals per fragment) in south Brazil. The bacterial community was identified via the high-throughput sequencing and partial amplification of the 16S rRNA gene (V4 region) using an Ion Personal Genome Machine (PGMTM) System. In contrast to other studies involving monkey microbiota, which have generally reported the phyla Firmicutes and Bacteroidetes as predominant, black capuchin monkeys showed a high relative abundance of Proteobacteria ( χ ¯ = 80.54%), followed by Firmicutes ( χ ¯ = 12.14%), Actinobacteria ( χ ¯ = 4.60%), and Bacteriodetes ( χ ¯ = 1.31%). This observed particularity may have been influenced by anthropogenic actions related to the wild habitat and/or diet specific to the Brazilian biome's characteristics and/or monkey foraging behavior. Comparisons of species richness (Chao1) and diversity indices (Simpson and InvSimpson) showed no significant differences between the two groups of monkeys. Interestingly, PICRUSt2 analysis revealed that metabolic pathways present in the bacterial communities were associated with xenobiotic biodegradation and the biosynthesis of secondary metabolites, which may suggest positive effects on monkey health and conservation in this anthropogenic habitat. Infectious disease-associated microorganisms were also observed in the samples. The present study provides information about the bacterial population and metabolic functions present in fecal microbiota, which may contribute to a better understanding of the ecology and biology of black capuchin monkeys living in forest fragments within the Atlantic Forest biome in southern Brazil. Additionally, the present study demonstrates that the fecal bacterial communities of wild black capuchin monkeys in this area are divergent from those of other wild non-human primates.

Schistosoma mansoni and soil transmtted helminths in olive baboons and potential zoonosis

Zoonotic pathogens are among the most important causes of ill health all over the world. The presence of these pathogens in free ranging baboons may have significant implications for humans. In Kenya, the encroachment of wildlife habitats has led to increased interaction between humans and wildlife especially non-human primates. The current study therefore aimed at investigating any possible zoonotic gastrointestinal helminths of olive baboons (Papio anubis) at the human-wildlife interface in two park borders and a ranch in Kenya, namely, Tsavo West National Park, Tana River Primate Reserve and Mutara Ranch, Laikipia, Kenya. One hundred and forty-seven baboons were used in the study. They were trapped in the wild, sampled for stool marked and then released back to the wild. Gastrointestinal (GIT) helminths identified were Strongyloides, Oesophagostomum, Enterobius spp and Trichuris Trichiura from all the three sites while Schistosoma mansoni was only detected from Tsavo baboons and with very low incidence (2.1%). The prevalence of these parasites varied among the sites but significant difference in prevalence was only noted in Strongyloides and Oesophagostomum (p < 0.05) among the three sites. This therefore implies that even with control measures instituted on the human population, baboons will always be a source of zoonotic GIT helminths especially S. mansoni even if the incidence are low. There is need to put in place measures aiming to reduce their interactions with humans and also try to control these infections in the baboons.

The Gastrointestinal Microbiota of the Common Marmoset (Callithrix jacchus)

The microbiota is heavily involved in both health and disease pathogenesis, but defining a normal, healthy microbiota in the common marmoset has been challenging. The aim of this review was to systematically review recent literature involving the gastrointestinal microbiome of common marmosets in health and disease. Twelve sources were included in this review. The gut microbiome composition was reviewed across institutions worldwide, and taxonomic shifts between healthy individuals were described. Unlike the human gut microbiome, which is dominated by Firmicutes and Bacteroidetes, the marmoset gut microbiome shows great plasticity across institutions, with 5 different phyla described as dominant in different healthy cohorts. Genera shared across institutions include Anaerobiospirillum, Bacteroides, Bifidobacterium, Collinsella, Fusobacterium, Megamonas, Megasphaera, Phascolarctobacterium, and Prevotella. Shifts in the abundance of Prevotella or Bifidobacterium or invasion by pathogens like Clostridium perfringens may be associated with disease. Changes in microbial composition have been described in healthy and diseased marmosets, but factors influencing the severe changes in microbial composition have not been established. Multi-institutional, prospective, and longitudinal studies that utilize multiple testing methodologies are required to determine sources of variability in the reporting of marmoset microbiomes. Furthermore, methods of microbial manipulation, whether by diet, enrichment, fecal microbiome transplantation, etc, need to be established to modulate and maintain robust and resilient microbiome communities in marmoset colonies and reduce the incidence of idiopathic gastrointestinal disease.

Prevalence of Vancomycin-Resistant Enterococcus (VRE) in Companion Animals: The First Meta-Analysis and Systematic Review

Antimicrobial resistance in companion animals is a major public health concern worldwide due to the animals’ zoonotic potential and ability to act as a reservoir for resistant genes. We report on the first use of meta-analysis and a systematic review to analyze the prevalence of vancomycin-resistant Enterococcus (VRE) in companion animals. Databases such as MedLib, PubMed, Web of Science, Scopus, and Google Scholar were searched. The information was extracted by two independent reviewers and the results were reviewed by a third. Two reviewers independently assessed the study protocol using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist and the study quality using the Joanna Briggs Institute (JBI) critical appraisal checklist for prevalence data. OpenMeta analyst and comprehensive meta-analysis (CMA) were used for the meta-analysis. The random effect model was used, and publication bias was assessed using the Eggers test and funnel plot. Between-study heterogeneity was assessed, and the sources were analyzed using the leave-one-out meta-analysis, subgroup analysis and meta-regression. Twenty-two studies met the eligibility criteria, but because some studies reported the prevalence of VRE in more than one companion animal, they were considered as individual studies, and 35 studies were therefore added to the final meta-analysis. Sampling period of the included studies was from 1995–2018. Of the 4288 isolates tested in the included studies, 1241 were VRE. The pooled prevalence of VRE in companion animals was estimated at 14.6% (95% CI; 8.7–23.5%; I² = 97.10%; p < 0.001). Between-study variability was high (t² = 2.859; heterogeneity I² = 97.10% with heterogeneity chi-square (Q) = 1173.346, degrees of freedom (df) = 34, and p < 0.001). The funnel plot showed bias, which was confirmed by Eggers test (t-value = 3.97165; p = 0.00036), and estimates from the leave-one-out forest plot did not affect the pooled prevalence. Pooled prevalence of VRE in dogs and cats were 18.2% (CI = 9.4–32.5%) and 12.3%, CI = 3.8–33.1%), respectively. More studies were reported in Europe than in any other continent, with most studies using feces as the sample type and disc diffusion as the detection method. With the emergence of resistant strains, new antimicrobials are required in veterinary medicine.

Cytotoxic Escherichia coli strains encoding colibactin, cytotoxic necrotizing factor, and cytolethal distending toxin colonize laboratory common marmosets (Callithrix jacchus)

Cyclomodulins are virulence factors that modulate cellular differentiation, apoptosis, and proliferation. These include colibactin (pks), cytotoxic necrotizing factor (cnf), and cytolethal distending toxin (cdt). Pathogenic pks+, cnf+, and cdt+ E. coli strains are associated with inflammatory bowel disease (IBD) and colorectal cancer in humans and animals. Captive marmosets are frequently afflicted with IBD-like disease, and its association with cyclomodulins is unknown. Cyclomodulin-encoding E. coli rectal isolates were characterized using PCR-based assays in healthy and clinically affected marmosets originating from three different captive sources. 139 E. coli isolates were cultured from 122 of 143 marmosets. The pks gene was detected in 56 isolates (40%), cnf in 47 isolates (34%), and cdt in 1 isolate (0.7%). The prevalences of pks+ and cnf+ E. coli isolates were significantly different between the three marmoset colonies. 98% of cyclomodulin-positive E. coli belonged to phylogenetic group B2. Representative isolates demonstrated cyclomodulin cytotoxicity, and serotyping and whole genome sequencing were consistent with pathogenic E. coli strains. However, the presence of pks+, cnf+, or cdt+ E. coli did not correlate with clinical gastrointestinal disease in marmosets. Cyclomodulin-encoding E. coli colonize laboratory common marmosets in a manner dependent on the source, potentially impacting reproducibility in marmoset models.