Mycobacterium avium subsp. hominissuis infection in 2 pet dogs, Germany

Nontuberculous Mycobacteria in Horses: A Narrative Review

Nontuberculous mycobacteria (NTM) infections are increasing in human and veterinary medicine. Although horses were initially thought to be resistant to NTM infection, reports of horses suffering from gastrointestinal, respiratory, and reproductive diseases associated with NTM have increased in the last few decades. The aim of this literature review is to summarize the mycobacteria species found in horses, describe clinical manifestations, diagnostic and treatment approaches, and public health concerns of NTM infection in horses. Clinical manifestations of NTM in horses include pulmonary disease, lymphadenitis, soft tissue, bone infections, and disseminated disease. NTM are also linked to granulomatous enteritis, placentitis, and abortions. Currently, diagnostic methods for NTM are limited and include acid-fast microscopy, bacterial cultures, species-specific PCR assays, and gene sequencing. In humans, NTM treatment guidelines are available, but their application appears inadequate and inconsistent. In horses, treatment guidelines for NTM infections are not available. NTM are a serious public health threat as 70% of people with untreated acquired immunodeficiency syndrome (AIDS) have a chronic pulmonary disease caused by NTM. Thus, it is essential that we gain a better understanding of NTM infections in horses and their zoonotic potential.

Mycobacterium avium in miniature schnauzer from Argentina: a series of cases

Environmental mycobacteria such as those from the Mycobacterium avium-intacellulare complex may cause disseminated and severe disease in dogs with genetic predisposition. A series of cases of four miniature schnauzers with nonspecific clinical signs and the diagnostic tests are described. Complementary means of diagnosis including complete blood count, biochemical serum analyses and fine needle aspiration cytology staining were performed. The bacteriological culture followed by PCR amplification of 1245 and 901 insertion sequences, allowed the identification of Mycobacterium avium subsp. hominissuis. This environmental Mycobacteria normally do not cause severe disease in dogs or other species, but when CARD-9 gene presents mutations, dogs may become extremely susceptible and disease is fast, disseminated and fatal. Antibiotic therapy can be applied under veterinary consideration in specific situations, as treatment is usually applied for a long period of time. Although zoonotic risk is low as the Mycobacterium is environmental, contamination of the location may be high, and immunosuppressed animals and humans can develop infection as well. This report may aid clinical veterinarians in the diagnosis, treatment, and prognosis in similar cases of this breed and others with the genetic predisposition.

Mycobacterium intracellulare induces a Th17 immune response via M1-like macrophage polarization in canine peripheral blood mononuclear cells

Mycobacterium avium-intracellulare complex (MAC) is one of the most prevalent pathogenic nontuberculous mycobacteria that cause chronic pulmonary disease. The prevalence of MAC infection has been rising globally in a wide range of hosts, including companion animals. MAC infection has been reported in dogs; however, little is known about interaction between MAC and dogs, especially in immune response. In this study, we investigated the host immune response driven by M. intracellulare using the co-culture system of canine T helper cells and autologous monocyte-derived macrophages (MDMs). Transcriptomic analysis revealed that canine MDMs differentiated into M1-like macrophages after M. intracellulare infection and the macrophages secreted molecules that induced Th1/Th17 cell polarization. Furthermore, canine lymphocytes co-cultured with M. intracellulare-infected macrophages induced the adaptive Th17 responses after 5 days. Taken together, our results indicate that M. intracellulare elicits a Th17 response through macrophage activation in this system. Those findings might help the understanding of the canine immune response to MAC infection and diminishing the potential zoonotic risk in One Health aspect.

TREATMENT OF MYCOBACTERIOSIS CAUSED BY MYCOBACTERIUM AVIUM SSP. HOMINISSUIS IN A GROUP OF CAPTIVE LOWLAND TAPIRS (TAPIRUS TERRESTRIS)

Tapirs are a taxonomic group with a high susceptibility to mycobacterial diseases. However, successful therapy has only been documented sporadically. Here treatment of mycobacteriosis diagnosed in three, one male and two female, lowland tapirs (Tapirus terrestris) in a zoo in Germany is reported. Two of the animals showed chronic mild respiratory signs, and conventional therapy did not improve the condition. Culture of broncho-alveolar lavage (BAL) samples was positive for Mycobacterium avium ssp. hominissuis. Upon airway endoscopy, bronchial edema and increased mucus production were visible. Initially, all three infected tapirs received oral antimycobacterial therapy consisting of 5 mg/kg body weight isoniazid, 10 mg/kg rifampicin, and 10 mg/kg clarithromycin q24h. Based on therapeutic drug level monitoring, the doses of rifampicin were adjusted to 12 and 15 mg/kg in the females and the male, respectively. The treatment with all three drugs was continued for 11 mon. Six months into treatment, the clinical condition resolved, and repeated BAL samples of all three tapirs tested negative for mycobacteria by culture. Here the approach for a treatment protocol with minimal side effects suitable to control infections with nontuberculous mycobacteria in lowland tapirs is reported.

Mycobacterium avium infection associated with sterile polyarthritis in a dog

A 1-year-old male neutered Portuguese Podengo dog was presented for lameness, inappetence, pyrexia, diarrhoea and abdominal moderate to severe lymphadenomegaly. Cytology of synovial fluid revealed neutrophilic inflammation in multiple joints suggestive of immune-mediated polyarthritis. Cytology of fine-needle-aspiration material obtained from lymph nodes revealed macrophages with intracytoplasmic, rod-like Ziehl-Neelsen positive staining structures, indicative of mycobacteria. Four-month treatment with enrofloxacin, rifampicin and clarithromycin resulted in clinical improvement and resolution of polyarthritis as evidenced on repeat synoviocentesis, but diarrhoea recurred, Ziehl-Neelsen positive organisms were again found on lymph node cytology and analysis of the 16S rRNA-gene using the Basic Local Alignment Search Tool facility resulted in a match to Mycobacterium avium with 100% sequence identity. Treatment was adjusted to include pradofloxacin, doxycycline, rifampicin and ethambutol and 3 months later the dog is clinically normal. Based on the literature search, this is the first time canine Mycobacterium avium infection associated with immune-mediated polyarthritis is reported. Based on scoping searches, this is the first report of canine Mycobacterium avium infection associated with immune-mediated polyarthritis.

Mycobacterium tuberculosis SIT42 Infection in an Abused Dog in Southern Italy

A case of Mycobacterium tuberculosis infection is described in a dead adult male dog in Southern Italy. The carcass was found by the Health Authority in a gypsy encampment. It was admitted to our forensic veterinary medicine unit, with a suspicion of cruelty to the animal. Necropsy showed beating and traumatism signs, and mistreating was confirmed. Gross lesions included multiple nodular hepatic lesions, hemorrhagic enteritis with enlarged mesenteric lymph nodes, body cavity effusions, and an adrenal neoplasm. Bacteriological and molecular analyses were carried out on the liver lesions that enabled to identify M. tuberculosis SIT42 (LAM9). Drug-resistance patterns were evaluated by screening mutations on the rpoB and katG genes that showed susceptibility to both rifampin and isoniazid, respectively. Very few studies report canine tuberculosis, and little is known about the disease in Italy. To the authors' knowledge, this is the first report of Mycobacterium tuberculosis SIT42 infection in a dog in Italy.

Mycobacterium avium Modulates the Protective Immune Response in Canine Peripheral Blood Mononuclear Cells

Mycobacterium avium, an opportunistic intracellular pathogen, is a member of the non-tuberculous mycobacteria species. M. avium causes respiratory disease in immunosuppressed individuals and a wide range of animals, including companion dogs and cats. In particular, the number of infected companion dogs has increased, although the underlying mechanism of M. avium pathogenesis in dogs has not been studied. Therefore, in the present study, the host immune response against M. avium in dogs was investigated by transcriptome analysis of canine peripheral blood mononuclear cells. M. avium was shown to induce different immune responses in canine peripheral blood mononuclear cells at different time points after infection. The expression of Th1-associated genes occurred early during M. avium infection, while that of Th17-associated genes increased after 12 h. In addition, the expression of apoptosis-related genes decreased and the abundance of intracellular M. avium increased in monocyte-derived macrophages after infection for 24 h. These results reveal the M. avium induces Th17 immune response and avoids apoptosis in infected canine cells. As the number of M. avium infection cases increases, the results of the present study will contribute to a better understanding of host immune responses to M. avium infection in companion dogs.

Acid-base variables in acute and chronic form of nontuberculous mycobacterial infection in growing goats experimentally inoculated with Mycobacterium avium subsp. hominissuis or Mycobacterium avium subsp. paratuberculosis

In current literature, data assessing the acid-base equilibrium in animals and humans during bacterial infection are rare. This study aimed to evaluate acid-base deteriorations in growing goats with experimentally induced NTM (nontuberculous mycobacteria) infections by application of the traditional Henderson-Hasselbalch approach and the strong ion model. NTM-challenged animals were orally inoculated with either Mycobacterium avium subsp. hominissuis (MAH; n = 18) or Mycobacterium avium subsp. paratuberculosis (MAP; n = 48). Twenty-five goats served as non-infected controls. Until 51^st week post-inoculation (wpi), blood gas analysis, serum biochemical analysis, and serum electrophoresis were performed on venous blood. Fifty percent (9/18) of goats inoculated with MAH developed acute clinical signs like apathy, fever, and diarrhea. Those animals died or had to be euthanized within 11 weeks post-inoculation. This acute form of NTM-infection was characterized by significantly lower concentrations of sodium, calcium, albumin, and total protein, as well as significantly higher concentrations of gamma globulin, associated with reduced albumin/globulin ratio. Acid-base status indicated alkalosis, but normal base excess and HCO₃^- concentrations, besides significantly reduced levels of SID (strong ion difference), A_{tot Alb} (total plasma concentration of weak non-volatile acids, based on albumin), A_{tot TP} (A_tot based on total protein) and markedly lower SIG (strong ion gap). The remaining fifty percent (9/18) of MAH-infected goats and all goats challenged with MAP survived and presented a more sub-clinical, chronic form of infection mainly characterized by changes in serum protein profiles. With the progression of the disease, concentrations of gamma globulin, and total protein increased while albumin remained lower compared to controls. Consequently, significantly reduced albumin/globulin ratio and lower A_{tot Alb} as well as higher A_{tot TP} were observed. Changes were fully compensated with no effect on blood pH. Only the strong ion variables differentiated alterations in acid-base equilibrium during acute and chronic NTM-infection.

Isolation, Molecular Typing, and Antibiotic Susceptibility Testing of Mycobacterium avium Subspecies hominissuis From a Dog With Generalized Mycobacteriosis

Mycobacterium avium-intracellulare complex infections are becoming an increasing concern in veterinary medicine because they affect livestock, wildlife, and companion animals. Here we describe the isolation, molecular typing, and antibiotic susceptibility testing of the causative agent of a rare case of generalized mycobacteriosis in a crossbred dog. Mycobacterial colonies were isolated from a popliteal lymph node aspirate sample and molecular typed by SNPs typing of the genes gyrB and rpsA, the 3′ region of the hsp65 gene and the internal transcribed spacer (ITS), and MIRU-VNTR analysis. Colonies were also tested in vitro against the macrolide clarithromycin and other drugs, using a resazurin microdilution assay, in order to provide the most appropriate treatment for the dog. Results from SNPs typing of gyrB and ITS, as well as from MIRU-VNTR analysis suggested the isolation of a single strain of M. avium subsp. hominissuis (Mah). On the other hand, SNP typing of rpsA revealed DNA polymorphisms that led colonies to cluster into two groups. The presence of two distinct strains of Mah has been assumed. All colonies, regardless of the nucleotide sequence of rpsA, were found to be sensitive to all of the drugs tested except for ethambutol. Although the therapy administered was adequate, the dog's overall clinical status worsened progressively and the animal died 8 months later. In conclusion, we report on the isolation of Mah from a dog with generalized mycobacteriosis.

Disseminated Mycobacterium avium subsp. hominissuis infection and ascites in an FIV-positive cat

A domestic shorthair cat was presented to the Veterinary Teaching Hospital at The University of the West Indies with a history of anorexia, ataxia, and lethargy. On physical examination, moderate abdominal distension and a palpable abdominal fluid wave were noted. Dark yellow, cloudy fluid was collected via abdominocentesis. Fluid analysis indicated that the effusion was a transudate containing low numbers of macrophages and occasional neutrophils. Some of the macrophages contained rod-shaped nonstaining structures of variable length (2-4 um). These structures were also seen extracellularly in low numbers. The morphology of the structures was suggestive of Mycobacterium. The cat's condition continued to deteriorate, and it died within a few hours of being admitted. Further diagnostic tests revealed feline immunodeficiency virus (FIV) infection with concurrent Mycobacterium avium subsp hominissuis infection. To the authors' knowledge, this is the first reported case of nontubercular mycobacterial-related ascites in a cat.

Clinical outcome and diagnostic methods of atypical mycobacteriosis due to Mycobacterium avium ssp. hominissuis in a group of captive lowland tapirs (Tapirus terrestris)

Tapirs seem particularly susceptible to mycobacterial infections, especially to tuberculosis caused by M. tuberculosis or M. bovis. In this case series, we report an infection with the non-tuberculous mycobacteria (NTM) species M. avium ssp. hominissuis (MAH) in a group of four (2.2) captive lowland tapirs (Tapirus terrestris). Two female tapirs showed mild respiratory signs such as coughing and mucous sputum production for several years, one juvenile male tapir had to be euthanized due to severe dyspnoea, and the adult male only showed mild respiratory signs in 2010. Post-mortem histopathology of the euthanized animal revealed a chronic bronchopneumonia, and MAH was detected via culture. Subsequently, the three remaining tapirs were tested further: serologically, the tapirs had high antibody titres against M. avium, but they showed no reaction in the comparative skin test (TST). At several time points, the animals were tested for the presence of mycobacteria in different sample matrices including sputum samples, pooled faecal samples as well as swabs from the tapir enclosure to identify potential environmental niches of the pathogen. Moreover, animals were directly sampled using nasal swabs, endoscopic broncho-alveolar (BAL) and gastric lavages. MAH was detected by culture in the sputum samples, in the BAL of the breeding pair, as well as in the swimming pool water and walls, and in swabs taken from the tapir's sleeping beds. We conclude that the TST is not a useful diagnostic tool to detect MAC infections in tapirs, whereas antibody ELISA and culture from BAL appear more sensitive.

Molecular and Serological Footprints of Mycobacterium avium Subspecies Infections in Zoo Animals

Background: Mycobacteria of the Mycobacterium avium complex (MAC) pose a significant risk to zoological collections. Mycobacterium avium subspecies paratuberculosis (MAP) is a member of MAC and the causative agent of Johne’s disease. Despite many reports in animals kept in zoological gardens, systemic surveillance has rarely been reported. Methods: In this study, archived serum samples collected from animal species at the Wilhelma Zoological and Botanical Gardens in Stuttgart, Germany, were screened for the presence of antibodies against MAC and MAP. In addition, molecular investigations were performed on necropsy, fecal, and environmental samples. Results: In total, 30/381 serum samples of various mammalian species were positive for MAC antibodies in ELISA, while one sample of a reticulated giraffe (Giraffa camelopardalis reticulata) was positive in MAP-specific ELISA. Samples from many species were positive in pan-Mycobacterium real-time PCR (40/43 fecal samples, 27/43 environmental samples, and 31/90 necropsy samples). Surprisingly, no sample was positive in the MAP-specific molecular assays. However, two environmental samples from primate enclosures were positive in Mycobacterium avium subspecies hominissuis (MAH)-specific real-time PCR. Conclusions: The results reveal serological indications of MAC infections in the zoological collection. However, the presence of a MAP-contaminated environment by a high-shedding individual animal or MAP-infected population is unlikely.

Mycobacterium avium: an Emerging Pathogen for Dog Breeds with Hereditary Immunodeficiencies

Purpose of Review

Among the nontuberculous mycobacteria (NTM), Mycobacterium avium complex (MAC) is the leading cause of pulmonary disease in humans. Innate and acquired immunodeficiencies have been associated with an increased host susceptibility to NTM infections. The underlying mechanisms predisposing humans and dogs to MAC infections is being elucidated.

Recent Findings

Although MAC infection is infrequently diagnosed in dogs, a strong breed predisposition particularly for Miniature Schnauzer and Basset Hound dogs is evident. A recessively inherited defect of the adaptor protein CARD9 has recently been documented to be responsible for the increased susceptibility to MAC in the Miniature Schnauzer breed.

Summary

Given the zoonotic potential of a MAC infected dog particularly to immunocompromised human patients, diseased dogs pose a public health risk. While not a reportable disease, treatment of systemic mycobacteriosis is generally not effective and discouraged in dogs. The collaborative efforts by microbiologists, veterinary clinicians, dog breeders, primary care physicians, and infectious disease specialists applying the One Health approach is therefore crucial for the best management and prevention of MAC infection.

Unusual presentation of canine Mycobacterium avium infection

This short communication describes the clinical and morphological findings, diagnosis and treatment of a case of Mycobacterium avium infection in a golden retriever that presented with a progressive nasal swelling and lymphadenopathy. Although well documented in cats, where cutaneous lesions are frequently recognised, canine M avium infection is less commonly reported, and cutaneous lesions are rare. To the authors' knowledge this is the first documented case of canine M avium infection that presented with a cutaneous lesion but no systemic clinical signs. It occurred in a dog with no previously reported breed predisposition and highlights that in cases of cutaneous histiocytic infiltrate in dogs mycobacterial infection should remain a differential diagnosis, even in the absence of suggestive organisms on histopathological examination.

Mycobacterium avium subsp. hominissuis Infection in a Domestic Rabbit, Germany

Mycobacterium avium subsp. hominissuis is an opportunistic pathogen present in soil and dust. We report M. avium subsp. hominissuis infection found in a domestic rabbit in Hannover, Germany, in May 2017.

Phylogenetic uniqueness of Mycobacterium avium subspecies hominissuis isolated from an abnormal pulmonary bovine case

Mycobacterium avium subspecies hominissuis (MAH) is an important cause of infection in human pulmonary and swine intestinal cases. Although MAH is isolated from environmental sources frequently, infections of other animals have rarely been analysed. Recently, we detected granulomatous inflammation in bovine lung as an abnormal postmortem inspection case. To ascertain its genetic profile, we conducted a variable numbers of tandem repeats (VNTR) analysis and genomic characterization using deep sequencing. The VNTR type was a unique profile that differed from reported genotypes, but it was assigned within a broad genotypic complex of isolates from human patients and bathrooms. Genomic comparison with 116 registered genome sequences of the subspecies revealed that the strain was separate from five major genetic population groups proposed previously. Although the infection source remains unclear, its isolation from various resources such as animal infection cases should be elucidated more extensively to reveal its genetic diversity and ecological context.

Mycobacterium avium subsp. hominissuis menigoencephalitis in a cat

A 33-month old, neutered female Abyssinian cat died. The cat had sudden onset of widespread neurologic signs about half a year after birth. Mycobacterium avium subsp. hominissuis (MAH) group was isolated and identified from the brain of a cat affected with pyogranulomatous meningoencephalitis. The central nervous system (CNS) was involved in the disseminated MAH infection. MAH infection should be considered in cats with neurologic signs in regard to zoonotic aspects. Comparatively, this is a first case of MAH infection observed in the brain in either humans or animals.

Pathological findings in the red fox (Vulpes vulpes), stone marten (Martes foina) and raccoon dog (Nyctereutes procyonoides), with special emphasis on infectious and zoonotic agents in Northern Germany

Anthropogenic landscape changes contributed to the reduction of availability of habitats to wild animals. Hence, the presence of wild terrestrial carnivores in urban and peri-urban sites has increased considerably over the years implying an increased risk of interspecies spillover of infectious diseases and the transmission of zoonoses. The present study provides a detailed characterisation of the health status of the red fox (Vulpes vulpes), stone marten (Martes foina) and raccoon dog (Nyctereutes procyonoides) in their natural rural and peri-urban habitats in Schleswig-Holstein, Germany between November 2013 and January 2016 with focus on zoonoses and infectious diseases that are potentially threatening to other wildlife or domestic animal species. 79 red foxes, 17 stone martens and 10 raccoon dogs were collected from traps or hunts. In order to detect morphological changes and potential infectious diseases, necropsy and pathohistological work-up was performed. Additionally, in selected animals immunohistochemistry (influenza A virus, parvovirus, feline leukemia virus, Borna disease virus, tick-borne encephalitis, canine adenovirus, Neospora caninum, Toxoplasma gondii and Listeria monocytogenes), next-generation sequencing, polymerase chain reaction (fox circovirus) and serum-neutralisation analysis (canine distemper virus) were performed. Furthermore, all animals were screened for fox rabies virus (immunofluorescence), canine distemper virus (immunohistochemistry) and Aujeszky's disease (virus cultivation). The most important findings included encephalitis (n = 16) and pneumonia (n = 20). None of the investigations revealed a specific cause for the observed morphological alterations except for one animal with an elevated serum titer of 1:160 for canine distemper. Animals displayed macroscopically and/or histopathologically detectable infections with parasites, including Taenia sp., Toxocara sp. and Alaria alata. In summary, wildlife predators carry zoonotic parasitic disease and suffer from inflammatory diseases of yet unknown etiology, possibly bearing infectious potential for other animal species and humans. This study highlights the value of monitoring terrestrial wildlife following the "One Health" notion, to estimate the incidence and the possible spread of zoonotic pathogens and to avoid animal to animal spillover as well as transmission to humans.

Avian Mycobacteriosis: Still Existing Threat to Humans

The nontuberculous mycobacteria are typically environmental organisms residing in soil and water. These microorganisms can cause a wide range of clinical diseases; pulmonary disease is most frequent, followed by lymphadenitis in children, skin and soft tissue disease, and rare extra pulmonary or disseminated infections. Mycobacterium avium complex is the second most common cause of pulmonary mycobacterioses after M. tuberculosis. This review covers the clinical and laboratory diagnosis of infection caused by the members of this complex and particularities for the treatment of different disease types and patient populations.

Experimental Infection of Goats with Mycobacterium avium subsp. hominissuis: a Model for Comparative Tuberculosis Research

Mycobacterium avium subsp. hominissuis (MAH) is an opportunistic pathogen that causes infections in man and animals. In this study, 18 goat kids were inoculated orally with a high dose of MAH. One group of goats (n = 9) developed severe clinical disease for up to 2-3 months post inoculation (mpi). At necropsy examination, there were ulcerative and granulomatous lesions in gut-associated lymphoid tissue and granulomas with extensive necrosis in the lymph nodes (LNs) of the cranial mesenteric lymphocentre (CMLNs). Culture revealed growth of MAH in all lesions with systemic spread. A second group of goats were healthy at the end of the trial (13 mpi); however, all had extensive granulomas in the CMLNs, but no extra-intestinal spread of bacteria. Moderate faecal shedding occurred in all goats up to 2 mpi. Microscopical characterization of the granulomas revealed solid non-necrotic, necrotic, calcified and fibrocalcified granulomas with resemblance to those seen in human and bovine tuberculosis. The two different courses of disease, with highly heterogenic lesions, systemic spread in goats with severe clinical disease and the development of granulomas of all stages in the surviving goats, makes the experimental infection of goats with MAH a valuable model for tuberculosis research. This model might allow new insights into host-pathogen interaction and anti-mycobacterial compound testing.

Intracardiac tuberculomas caused by Mycobacterium tuberculosis in a dog

Background

This paper presents an unusual form of disseminated Mycobacterium tuberculosis infection in a dog. The infection lasted at least one year and its main gross lesions were massive cardiac tuberculomas. To the best of our knowledge, this is the first report of heart tuberculomas in a dog.

Case presentation

A 9-year-old mixed-breed male dog weighing 10 kg was referred to the clinic for cardiological evaluation before general anesthesia. The echocardiography revealed a lump of about 20 mm in diameter in the area of the left atrium. Almost one year later the same dog was presented again in severe clinical state (fever, anorexia, weight loss, depression, cough, dyspnea, lymphadenomegaly, vomiting, recent episodes of fainting). Due to progression of the disease and poor effects of treatment the owner decided to euthanize the dog. Most prominent lesions observed during autopsy were diffuse pneumonia, fibrinous pericarditis and epicarditis as well as large, yellow, semisolid masses of caseous necrosis in the left and right atrium (30 mm and 15 mm in diameter, respectively). From both pulmonary and cardiac lesions M. tuberculosis was isolated on Lowenstein-Jensen slants and in Bactec Mycobacteria Growth Indicator Tube 960 liquid media, and confirmed by BD ProbeTec ET Direct Detection Assay and spoligotyping.

Conclusion

Companion animals may occasionally suffer from tuberculosis but majority of cases probably remain misdiagnosed or undetected. Typically tuberculosis in dogs affects lungs and their regional lymph nodes. Even in humans tuberculomas are rare manifestation of mycobacterial infection, mostly seen in the central nervous system. Atypical location of main tuberculous lesions may account for lack of correct ante mortem diagnosis in this case.

Molecular characterization and drug susceptibility profile of a Mycobacterium avium subspecies avium isolate from a dog with disseminated infection

Mycobacterium avium-intracellulare complex (MAC) infections have been described in many mammalian species, including humans and pets. We isolated and molecularly typed the causative agent of a rare case of disseminated mycobacteriosis in a dog. We identified the pathogen as M. avium subspecies avium by sequencing the partial genes gyrB and rpsA. Considering the zoonotic potential of this infection, and in an attempt to ensure the most effective treatment for the animal, we also determined the drug susceptibility profile of the isolate to the most common drugs used to treat MAC disease in humans. The pathogen was tested in vitro against the macrolide clarithromycin, as well as against amikacin, ciprofloxacin, rifampicin, ethambutol and linezolid, by the resazurin microdilution assay. It was found to be sensitive to all tested drugs apart from ethambutol. Despite the fact that the pathogen was sensitive to the therapies administered, the dog's overall clinical status worsened and the animal died shortly after antimicrobial susceptibility results became available. Nucleotide sequencing of the embB gene, the target gene most commonly associated with ethambutol resistance, showed new missense mutations when compared to sequences available in public databases. In conclusion, we molecularly identified the MAC pathogen and determined its drug susceptibility profile in a relatively short period of time (7 days). We also characterized new genetic mutations likely to have been involved in the observed ethambutol resistance. Our results confirmed the usefulness of both the gyrB and the rpsA genes as biomarkers for an accurate identification and differentiation of MAC pathogens.

Systemic infection of Mycobacterium avium subspecies hominissuis and fungus in a pet dog

A 3-year-old neutered female poodle with a long history of dermatophytic skin disease was presented with lethargy, anorexia and progressive weight loss. Abdominal ultrasonography revealed markedly enlarged mesenteric lymph nodes and multiple hypoechoic foci in the spleen. Cytology of the mesenteric lymph nodes and spleen showed granulomatous inflammation with fungal organisms and negatively stained intracytoplasmic bacterial rods consistent with Mycobacteria spp. Based on culture, multiplex polymerase chain reaction and sequence analysis, the bacterium was identified as Mycobacterium avium subspecies hominissuis. Despite treatment with antibiotics, the dog’s condition deteriorated, and it died approximately 3 weeks after first presentation.

A Case of DisseminatedMycobacterium aviumInfection in a Dog in Greece

A Basset Hound dog was presented with anorexia, fever, diarrhea, significant level of splenomegaly, and enlargement of mesenteric and superficial lymph nodes. Cytology of fine-needle-aspiration material, obtained from popliteal lymph node, revealed macrophages with intracytoplasmic, nonstaining, slender, rod-like structures, indicative of mycobacteria. Bacterial culture of lymph node aspirated material produced a colony which by means of molecular techniques (PCR amplification and hybridization of PCR products) was subsequently identified asMycobacterium avium. This is the first report of disseminatedM. aviuminfection in a dog in Greece.

Mycobacterium avium subspecies hominissuis disseminated infection in a Basset Hound dog

In the current report, a case in Italy of disseminated Mycobacterium avium subsp. hominissuis infection in a dog from an American lineage of Basset Hounds is described. A 2-year-old intact female Basset Hound presented with persistent lymphadenopathy, lameness, and a history characterized by coccidiosis, bacterial gastroenteritis, and alopecia. Lymphadenitis, with macrophages containing a few intracytoplasmic, negative staining, Ziehl-Neelsen-positive bacilli, was detected by a popliteal fine-needle aspirate leading to the diagnosis of mycobacteriosis. Ultrasound and X-ray examinations revealed visceral and mediastinal lymphadenopathy. Because of the extent of the disease, the dog was humanely euthanized. Significant gross abnormalities, such as enlargement of the cranial mediastinal lymph nodes with encapsulated areas of caseous necrosis and generalized lymphadenopathy, were observed at necropsy. Granulomatous lesions were histopathologically detected in the liver and spleen. Ziehl-Neelsen-positive bacilli were observed in all examined lymph node, liver, spleen, lung, and bone marrow smears. Lymph nodes and liver were collected in order to pursue speciation by bacterial culture and molecular biology; multiplex polymerase chain reaction results classified the pathogen as M. avium subsp. hominissuis. Although an immune system deficiency was not investigated, anamnesis suggests that the dog was immunocompromised. Furthermore, the dog came from an American stock of Basset Hound, and for some of this breed, a predisposition to this infection has been hypothesized.

Diversity of Mycobacterium avium subsp. hominissuis mycobacteria causing lymphadenitis, France

The knowledge of Mycobacterium avium complex (MAC) genotypes responsible for lymphadenitis is limited. We retrospectively characterized all of the MAC isolates made in our laboratory in the last 18 years by sequence-based identification and genotyping, and compared the clinical and laboratory data for lymphadenitis-associated and non-lymphadenitis-associated MAC isolates. Of 67 MAC-infected patients, 25 lymphadenitis patients were significantly younger than 42 non-lymphadenitis patients, while the male/female ratio did not significantly differ between the two groups. Cervical topography found in 76.5% of lymphadenitis patients was significantly more frequent in non-immunocompromised patients (p=0.04). M. avium subsp. hominissuis was identified in 53 patients (24 lymphadenitis, 29 non-lymphadenitis), M. colombiense in six patients (five non-lymphadenitis, one lymphadenitis), M. intracellulare in four non-lymphadenitis patients, and M. chimaera in three non-lymphadenitis patients, while negative controls remained negative. M. hominissuis was significantly associated with lymphadenitis (p=0.03). M. hominissuis isolates yielded 15 genotypes in 29 non-lymphadenitis isolates (molecular diversity, 0.622) versus 11 genotypes in 24 lymphadenitis isolates (molecular diversity, 0.578), demonstrating a non-significant lower diversity of M. hominissuis isolates cultured from lymphadenitis. The genotypes did not correlate with the clinical features. These data suggest the presence of several environmental reservoirs for M. hominissuis causing lymphadenitis in France.

Efficient differentiation of Mycobacterium avium complex species and subspecies by use of five-target multiplex PCR

Infections caused by the Mycobacterium avium complex (MAC) are on the rise in both human and veterinary medicine. A means of effectively discriminating among closely related yet pathogenetically diverse members of the MAC would enable better diagnosis and treatment as well as further our understanding of the epidemiology of these pathogens. In this study, a five-target multiplex PCR designed to discriminate MAC organisms isolated from liquid culture media was developed. This MAC multiplex was designed to amplify a 16S rRNA gene target common to all Mycobacterium species, a chromosomal target called DT1 that is unique to M. avium subsp. avium serotypes 2 and 3, to M. avium subsp. silvaticum, and to M. intracellulare, and three insertion sequences, IS900, IS901, and IS1311. The pattern of amplification results allowed determination of whether isolates were mycobacteria, whether they were members of the MAC, and whether they belonged to one of three major MAC subspecies, M. avium subsp. paratuberculosis, M. avium subsp. avium, and M. avium subsp. hominissuis. Analytical sensitivity was 10 fg of M. avium subsp. paratuberculosis genomic DNA, 5 to 10 fg of M. avium subsp. avium genomic DNA, and 2 to 5 fg of DNA from other mycobacterial species. Identification accuracy of the MAC multiplex was evaluated by testing 53 bacterial reference strains consisting of 28 different mycobacterial species and 12 nonmycobacterial species. Identification accuracy in a clinical setting was evaluated for 223 clinical MAC isolates independently identified by other methods. Isolate identification agreement between the MAC multiplex and these comparison assays was 100%. The novel MAC multiplex is a rapid, reliable, and simple assay for discrimination of MAC species and subspecies in liquid culture media.