Mycobacterium microti infection in two meerkats (Suricata suricatta)

Experimental Mycobacterium microti Infection in Bank Voles (Myodes glareolus)

Voles are maintenance hosts of Mycobacterium microti. In line with the goal to eradicate tuberculosis (TB) in livestock, the role of this mycobacteria needs to be assessed since it might interfere with current M. bovis/M. caprae surveillance strategies. To better understand the pathogenesis of TB in voles, an experimental infection model was set up to reproduce M. microti infection in laboratory Bank voles (Myodes glareolus). Two infection routes (intragastric and intraperitoneal) and doses (105 and 106 CFU/0.1 mL) were assessed. Voles were culled at different post-infection time points. Serology, histopathology, acid-fast bacilli staining, qPCR, and mycobacterial culture from tissues were performed. In addition, qPCR from feces and oral swabs were conducted to assess bacterial shedding. The model allowed us to faithfully reproduce the disease phenotype described in free-ranging voles and characterize the pathogenesis of the infection. Most animals showed multifocal and diffuse granulomatous lesions in the liver and spleen, respectively. Less frequently, granulomas were observed in lungs, lymph nodes, muscles, and salivary gland. Mycobacterial DNA was detected in feces from a few animals but not in oral swabs. However, one contact uninfected vole seroconverted and showed incipient TB compatible lesions, suggesting horizontal transmission between voles.

Ocular Tuberculosis: More than 'Of Mice and Men'

Tuberculosis (TB), caused by infection with members of the Mycobacterium tuberculosis-complex, is one of the oldest known infectious disease entities, resulting in the death of millions of humans each year. It also results in a substantial degree of morbidity and mortality in animal species. Extrapulmonary TB is well recognized in humans, and the eye is one site that can be affected. Studies seeking to understand ocular TB have often relied on animal models; however, these have their limitations and may not truly reflect what happens in humans. We wish to raise awareness among ophthalmologists and vision scientists of naturally occurring cases of ocular TB in animals, namely cattle and domestic cats, and the possibilities of gaining further understanding of this presentation of TB by adopting a collaborative approach. This will hopefully improve outcomes for both human and animal patients.

Mycobacterium microti Infections in Free-Ranging Red Deer (Cervus elaphus)

Infections with Mycobacterium microti, a member of the M. tuberculosis complex, have been increasingly reported in humans and in domestic and free-ranging wild animals. At postmortem examination, infected animals may display histopathologic lesions indistinguishable from those caused by M. bovis or M. caprae, potentially leading to misidentification of bovine tuberculosis. We report 3 cases of M. microti infections in free-ranging red deer (Cervus elaphus) from western Austria and southern Germany. One diseased animal displayed severe pyogranulomatous pleuropneumonia and multifocal granulomas on the surface of the pericardium. Two other animals showed alterations of the lungs and associated lymph nodes compatible with parasitic infestation. Results of the phylogenetic analysis including multiple animal strains from the study area showed independent infection events, but no host-adapted genotype. Personnel involved in bovine tuberculosis–monitoring programs should be aware of the fastidious nature of M. microti, its pathogenicity in wildlife, and zoonotic potential.

Pathogenomic analyses of Mycobacterium microti, an ESX-1-deleted member of the Mycobacterium tuberculosis complex causing disease in various hosts

Mycobacterium microti is an animal-adapted member of the Mycobacterium tuberculosis complex (MTBC), which was originally isolated from voles, but has more recently also been isolated from other selected mammalian hosts, including occasionally from humans. Here, we have generated and analysed the complete genome sequences of five representative vole and clinical M. microti isolates using PacBio- and Illumina-based technologies, and have tested their virulence and vaccine potential in SCID (severe combined immune deficient) mouse and/or guinea pig infection models. We show that the clinical isolates studied here cluster separately in the phylogenetic tree from vole isolates and other clades from publicly available M. microti genome sequences. These data also confirm that the vole and clinical M. microti isolates were all lacking the specific RD1mic region, which in other tubercle bacilli encodes the ESX-1 type VII secretion system. Biochemical analysis further revealed marked phenotypic differences between isolates in type VII-mediated secretion of selected PE and PPE proteins, which in part were attributed to specific genetic polymorphisms. Infection experiments in the highly susceptible SCID mouse model showed that the clinical isolates were significantly more virulent than the tested vole isolates, but still much less virulent than the M. tuberculosis H37Rv control strain. The strong attenuation of the ATCC 35872 vole isolate in immunocompromised mice, even compared to the attenuated BCG (bacillus Calmette-Guérin) vaccine, and its historic use in human vaccine trials encouraged us to test this strain's vaccine potential in a guinea pig model, where it demonstrated similar protective efficacy as a BCG control, making it a strong candidate for vaccination of immunocompromised individuals in whom BCG vaccination is contra-indicated. Overall, we provide new insights into the genomic and phenotypic variabilities and particularities of members of an understudied clade of the MTBC, which all share a recent common ancestor that is characterized by the deletion of the RD1mic region.

Mycobacterium microti: Not Just a Coincidental Pathogen for Cats

Public interest in animal tuberculosis is mainly focused on prevention and eradication of bovine tuberculosis in cattle and wildlife. In cattle, immunodiagnostic tests such as the tuberculin skin test or the interferon gamma (IFN-γ) assay have been established and are commercially available. Feline tuberculosis is rather unknown, and the available diagnostic tools are limited. However, infections with Mycobacterium tuberculosis complex members need to be considered an aetiological differential diagnosis in cats with granulomatous lymphadenopathy or skin nodules and, due to the zoonotic potential, a time-efficient and accurate diagnostic approach is required. The present study describes 11 independent cases of Mycobacterium microti infection in domestic cats in Switzerland. For three cases, clinical presentation, diagnostic imaging, bacteriological results, immunodiagnostic testing, and pathological features are reported. An adapted feline IFN-γ release assay was successfully applied in two cases and appears to be a promising tool for the ante mortem diagnosis of tuberculosis in cats. Direct contact with M. microti reservoir hosts was suspected to be the origin of infection in all three cases. However, there was no evidence of M. microti infection in 346 trapped wild mice from a presumptive endemic region. Therefore, the source and modalities of infection in cats in Switzerland remain to be further elucidated.

Mycobacterium microti Interferes with Bovine Tuberculosis Surveillance

Mycobacterium microti, a member of the Mycobacterium tuberculosis complex, was originally described as the cause of tuberculosis in wild rodents. However, in the last few years, an increasing number of cases have been reported in wildlife (wild boars and badgers) and livestock (goat and cattle) in the frame of bovine tuberculosis (bTB) surveillance program, demonstrating the risk of interference with bTB diagnosis in France. In 2019, we detected four cattle infected with M.microti, from three different herds in three different distant regions. For all these cases, ante-mortem diagnosis by the skin test (single intradermal comparative cervical tuberculin (SICCT)) was positive. Confirmation of M.microti infection was based on molecular tests, i.e., specific real-time PCR and spoligotyping. These results highlight a non-negligible risk of interference in the bTB diagnosis system and raise concern about the reliability of diagnostic tests used for bTB surveillance. The use of highly specific tests, like the interferon gamma test (IFN-γ) employed in France or new synthetic specific tuberculins for skin testing could alternatively be used to accurately identify M.bovis (or Mycobacterium caprae) infection at ante-mortem examination. At post-mortem diagnosis, the use of specific molecular tools should be considered to accurately distinguish pathogens within the MTBC and to avoid misleading bTB diagnosis.

Procyonidae, Viverridae, Hyenidae, Herpestidae, Eupleridae, and Prionodontidae

This chapter covers the diseases and pathology of multiple taxonomic groups within the order Carnivora including Procyonidae several of the Feliformia carnivores. The overwhelming majority of knowledge about disease pathogenesis for these species is biased toward raccoons and concern for disease spread to humans and companion animals. Procyonids and feliform carnivores are ubiquitous in their environments and share habitat and environmental resources with other nondomestic and domestic carnivores and humans. As reservoirs for a number of important multispecies or zoonotic pathogens, surveys for pathogens that may be harbored or vectored by several of the species in this chapter, for example, raccoons (e.g., canine distemper virus, rabies, and leptospirosis) and civets (e.g., SARS coronavirus), have been active areas of investigation. Unfortunately, less research has focused on the potential effects of these pathogens on their hosts.

Yersiniosis due to infection by Yersinia pseudotuberculosis 4b in captive meerkats (Suricata suricatta) in Japan

Two meerkats ( Suricata suricatta) housed in the same zoological garden in Japan died due to Yersinia pseudotuberculosis serotype 4b infection. Gross and microscopic lesions included necrotizing enteritis and enlargement of the spleen and liver with multifocal necrosis. Inflammatory cells, primarily neutrophils, and nuclear debris were associated with clusters of Gram-negative bacilli. Additionally, there were aberrant organism forms that were larger than bacilli and appeared as basophilic globular bodies. Immunohistochemical examination showed that the bacilli and globular bodies were strongly positive for Y. pseudotuberculosis O4 antigen. The globular bodies were considered a shape-changed form of Y. pseudotuberculosis, and these morphologically abnormal bacteria could present a diagnostic challenge.

Infection with Mycobacterium microti in animals in France

We describe here 35 animal cases of tuberculosis due to Mycobacterium microti in France (2002-2014). Recently, molecular tools that overcome the difficulty of confirming infection by this potentially zoonotic agent have revealed an increasing number of cases, suggesting that its prevalence may have been underestimated.

Disseminated Mycobacterium bovis infection in red foxes (Vulpes vulpes) with cerebral involvement found in Portugal

A total of 49 road-killed red foxes were used for the detection of Mycobacterium tuberculosis complex (MTC) in Portugal. MTC infection was detected by PCR in 10 red foxes (20.4%; 95% confidence interval [CI] 8.8-31.2%) and confirmed in three (6.1%; 95% CI 0.0-7.9%) of them by microbiological culture. The complex was detected in 20 tissues out of 441 by PCR techniques (4.5%; 95% CI 16.3-23.7%) and in seven tissues out of 441 (1.6%; 95% CI 4.6-9.4%) by culture. MTC was most frequently detected in the brain (8.2%) and in the mediastinal lymph nodes (8.2%). The seven cultures obtained were positive for M. bovis by PCR-based genotyping of the MTC targeting genomic deletions. This study confirms the presence of disseminated M. bovis in red foxes in Portugal, and it is the first report in the world of the natural infection in the animals' brains.

Detection and molecular characterization of Mycobacterium microti isolates in wild boar from northern Italy

Approximately 23,000 hunter-harvested wild boars from the pre-Alpine area of northern Italy were examined for tuberculosis over a 9-year period (2003 to 2011). Retropharyngeal and mandibular lymph nodes from the wild boars were examined grossly, and 1,151 of the lymph nodes were analyzed in our laboratory by histology (728 samples) and culture isolation (819 samples). Mycobacterium tuberculosis complex (MTBC)-specific PCR (1,142 samples) was used for molecular-level detection in tissue samples, as was a gyrB restriction fragment length polymorphism (RFLP) assay (322 samples). Lesions compatible with tuberculosis and indistinguishable from those described in cases of Mycobacterium bovis infection had been observed since 2003. Mycobacterium microti was identified directly in 256 tissue samples by the adopted molecular approaches. However, only 26 M. microti strains were obtained by culture isolation due to the well-known difficulties in isolating this slow-growing mycobacterium. During 2006, a prevalence study was performed in two provinces of the area, and the diffusion of M. microti was calculated to be 5.8% (95% confidence intervals surrounding the estimated prevalences [CIP95%], 3.94 to 7.68%). Over the following years (2007 to 2011), the presence of M. microti appeared to be stable. All isolates were genotyped by spoligotyping and exact tandem repeat analysis (ETR types A to F). In addition to the typical vole type (SB0118), a new spoligotype lacking the 43 spacers was found. Spoligotyping was also applied directly to tissue samples, and a geographical cluster distribution of the two spoligotypes was observed. This is the first report studying the diffusion and genetic variability of M. microti in wild boar.

Overview and phylogeny of Mycobacterium tuberculosis complex organisms: implications for diagnostics and legislation of bovine tuberculosis

Members of the Mycobacterium tuberculosis complex (MTBC) cause a serious disease with similar pathology, tuberculosis; in this review, bovine tuberculosis will be considered as disease caused by any member of the MTBC in bovids. Bovine tuberculosis is responsible for significant economic loss due to costly eradication programs and trade limitations and poses a threat to both endangered and protected species as well as to public health. We here give an overview on all members of the MTBC, focusing on their isolation from different animal hosts. We also review the recent advances made in elucidating the evolutionary and phylogenetic relationships of members of the MTBC. Because the nomenclature of the MTBC is controversial, its members have been considered species, subspecies or ecotypes, this review discusses the possible implications for diagnostics and the legal consequences of naming of new species.

Naming spoligotype patterns for the RD9-deleted lineage of the Mycobacterium tuberculosis complex; www.Mbovis.org

This www.Mbovis.org website and associated databases were initiated in response to the need of the Mycobacterium bovis molecular typing community for standardisation of nomenclature for spoligotype patterns. The purpose of the website is to provide standardised names for spoligotype patterns from strains of the RD9-deleted, lineage of the Mycobacterium tuberculosis complex. Each unique spoligotype pattern is named by 'SB' followed by a four integer number (e.g. SB0120) and the database currently records over 1400 patterns submitted by the research community over the last 9 years. The database holds information and authoritative names for spoligotype patterns from both clades of Mycobacterium africanum, M. bovis (antelope), Mycobacterium microti, Mycobacterium pinnipedii, Mycobacterium caprae and M. bovis. The history of the database is described, as well as the method for submitting new patterns to the database and the functionality of the website.