Volume 15, Number 4—April 2009
Mycobacterium avium subsp. hominissuis Infection in a Pet Parrot
To the Editor: Tuberculosis is a chronic wasting disease in domestic birds (especially hens) and free-ranging birds worldwide (1). Most mycobacterial infections in birds are caused by Mycobacterium avium subsp. avium (mainly domestic birds) or by M. genavense (especially pet birds). Nontuberculous (potentially pathogenic) mycobacteria (i.e., M. fortuitum, M. gordonae, and M. nonchromogenicum) occasionally have been isolated from necropsied pet birds (2). Because potentially pathogenic mycobacteria also are increasingly problematic in immunocompromised human patients, they merit special attention. M. avium subsp. hominissuis can infect humans, especially immunocompromised persons. M. avium subsp. hominissuis infections have been documented in pigs and cattle (3) and rarely in dogs (4), birds (5), and other animals.
We report a case of Mycobacterium infection in a female blue-fronted Amazon parrot (Amazona aestiva; pet bird) ≈6 months of age that was brought to a clinic because of inappetence over a 3-day period and polydipsia and yellow coloration of urine. Clinical examination showed slight emaciation, heavy biliverdinuria, ascites, and melena. By coprologic examination, 3 eggs of Ascaridia sp. worms were found in 1 field of view using 40× magnification. A Gram stain of fecal material showed sporadic gram-positive rods. On the basis of these signs, chlamydiosis was suspected. Differential diagnosis suggested liver cirrhosis, neoplasia, and Pacheco disease. Enrofloxacin (Baytril 2.5% injectable; Bayer AG, Frankfurt am Main, Germany) was administered subcutaneously (0.15 mL injected subcutaneously) and albendazole (Aldifal 2.5% suspension; Mevak a.s., Nitra, Slovakia) were administered orally (0.2 mL injected subcutaneously). The bird died 1 day later.
Necropsy showed ascites (clear yellowish fluid), hepatomegaly (stiff liver consistency, yellow-pink), mild splenomegaly, and hemorrhagic enteritis with thickening of the intestinal wall; the finding of hemorrhagic enteritis was unclear because the intestinal mucosa was hyperemic and covered with a thick layer of viscous mucus that contained blood. Twenty worms (Ascaridia sp.) were observed in the intestinal lumen.
Histopathologic examination showed diffused liver fibrosis with cystic dilatation of the bile ducts and focal extramedullary hematopoiesis. The hepatic parenchyma was nearly completely atrophic. Only some clusters of atrophic hepatocytes were observed. The other organs (kidneys, spleen, lungs, brain, and intestines) were free of histopathologic lesions. Hypertrophic cirrhosis (chronic active hepatitis) was diagnosed. Neither granulomatous nor other lesions were observed.
After Ziehl-Neelsen stain of tissue impressions, acid-fast rods (AFRs) were microscopically detected in the liver and intestine. Cultivation according to Matlova et al. (6) grew 6 acid-fast rod–positive isolates from 9 examined tissue specimens. A PCR assay confirmed M. avium spp., and a subsequent PCR assay for M. avium differentiation indicated M. avium subsp. hominissuis (IS1245+ and IS901–); both PCR assays were performed as described (7). The M. avium subsp. hominissuis isolate was classified as serotype 9. Typing of all isolates by IS1245 restriction fragment length polymorphism (RFLP) analysis according to Van Soolingen et al. (8) showed 2 different multibanded IS1245 RFLP types, which varied in only 1 band position (Table).
M. avium subsp. hominissuis is not considered an avian pathogen and rarely has been isolated from tuberculous lesions (5). However, our case study reports the isolation of M. avium subsp. hominissuis from multiple organs of 1 exotic bird that had developmental anomaly and liver fibrosis (Table). In addition to a few nonspecific gross lesions, nontuberculous lesions were observed in the liver, spleen, and intestinal organs.
The etiology of mycobacteriosis, especially in pet birds, is rarely identified. This may be because intravitam and postmortem findings are nonspecific. Infection with M. avium subsp. hominissuis may not lead to tuberculous lesions in birds, particularly when the infection occurs without complications. Susceptibility to mycobacterial infection, including M. avium subsp. hominissuis , depends on the host’s immune and nutritional status, environmental conditions unfavorable for the host, and genetic factors (1,9). Consistent with these reports, in this case, the histologic findings such as fibrosis of the liver associated with cystic dilatation and intestinal ascaris infestation may have aggravated the intensity of the mycobacterial infection.
IS1245 RFLP analysis showed isolates with 2 profiles that differ in the presence of only 1 band. The additional band in the rest of the isolates probably represents the transpositional event. The variability in 1 or 2 bands of 1 strain was also observed previously (10); therefore, we presume the bird was infected by only 1 strain of M. avium subsp. hominissuis . Unfortunately, the source of infection for this bird was not identified.
A multibanded IS1245 RFLP profile was described in a M. avium isolate from a parrot (4), but no details about this case were given. Our findings suggest that owners of pet birds and their family members may be at risk from this pathogenic causal agent. Hence, immunocompromised persons, children, and others involved in the breeding of exotic birds should avoid contact with birds with clinically suspected M. avium subsp. hominissuis .
We thank Eva Slezakova for technical assistance. We also thank Ludmila Faldikova and Neysan Donnelly for their critical grammatical corrections.
This study was supported by grant nos. MZE0002716201 and NPV 1B53009 from the Ministry of Agriculture of the Czech Republic and PathogenCombat (no. FOOD-CT-2005-007081, Brussels, EC).
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