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Disseminated infection with Mycobacterium genavense: a challenge to physicians and mycobacteriologists
V O Thomsen1, U B Dragsted, J Bauer
1Department of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark. vot@ssi.dk
Abstract:
In the present study we compared the clinical presentations of patients with a clinical diagnosis of AIDS and disseminated Mycobacterium genavense infection (n = 12) with those of patients with AIDS and disseminated M. avium complex (MAC) infection (n = 24). Abdominal pain was seen more frequently in the group of patients infected with M. genavense than in patients infected with MAC (P = 0. 003). Analysis of microbiological data revealed that stool specimens from patients infected with M. genavense were more often smear positive than stool specimens from patients infected with MAC (P = 0. 00002). However, M. genavense could be cultured on solid media from only 15.4% of the stool specimens, whereas MAC could be cultured from 71.4% of the specimens. Bone marrow and liver biopsy specimens yielded growth of M. genavense within a reasonably short time, allowing species identification by DNA technology. Microbiological data clearly demonstrated the importance of acidic liquid medium for primary culture, the avoidance of pretreatment and the use of additives in culture, and the necessity for prolonged incubation if M. genavense is suspected. Susceptibility testing showed that M. genavense is sensitive to rifamycins, fluoroquinolones, and macrolides, whereas it is resistant to isoniazid. Susceptibility to ethambutol and clofazimine could not be evaluated. The mean survival times of patients in the two groups were similar.
Insights
Disseminated Mycobacterium genavense infection in AIDS patients presents differently than M. avium complex (MAC). Microbiological detection of M. genavense requires specific culture methods, though it shows sensitivity to certain antibiotics.
Area of Science:
- Infectious Diseases
- Microbiology
- Clinical Medicine
Background:
- Disseminated Mycobacterium infections are significant opportunistic infections in patients with Acquired Immunodeficiency Syndrome (AIDS).
- Mycobacterium genavense and Mycobacterium avium complex (MAC) are common causes of disseminated mycobacterial disease in AIDS patients, but their clinical and microbiological distinctions are not fully elucidated.
Purpose of the Study:
- To compare the clinical presentations and microbiological findings of patients with AIDS and disseminated Mycobacterium genavense infection versus those with AIDS and disseminated MAC infection.
- To identify optimal microbiological methods for the detection and identification of Mycobacterium genavense.
Main Methods:
- Retrospective comparison of clinical data and microbiological results from 12 patients with M. genavense and 24 patients with MAC.
- Analysis of stool, bone marrow, and liver biopsy specimens.
- Evaluation of culture techniques, including media type, pretreatment, additives, and incubation time.
- DNA technology for species identification.
- Antimicrobial susceptibility testing.
Main Results:
- Abdominal pain was more frequent in M. genavense infected patients (P = 0.003).
- Stool specimens were more often smear-positive for M. genavense than MAC (P = 0.00002), but M. genavense culture yield from stool was lower (15.4% vs 71.4% for MAC).
- Bone marrow and liver biopsies facilitated M. genavense isolation and identification.
- Acidic liquid medium, avoidance of pretreatment, use of additives, and prolonged incubation are crucial for M. genavense detection.
- M. genavense demonstrated sensitivity to rifamycins, fluoroquinolones, and macrolides, but resistance to isoniazid.
Conclusions:
- Mycobacterium genavense and MAC infections in AIDS patients have distinct clinical and microbiological features.
- Optimized microbiological techniques, including specific culture media and prolonged incubation, are essential for diagnosing M. genavense.
- M. genavense exhibits a unique susceptibility profile, guiding potential therapeutic strategies.