Niacin-positive Mycobacterium kansasii isolated from immunocompromised patients

Abstract

Niacin-positive Mycobacterium kansasii was isolated from three patients, two with respiratory infections and one with a perirectal abscess. The isolates were phenotypically similar to other strains of M. kansasii, differing only in their ability to produce niacin. This phenotype has been reported only twice in the literature, during the 1960s. Mycobacterium kansasii has been reported previously to cause both pulmonary and extrapulmonary infections (2, 14, 15). In addition to chronic pulmonary disease, M. kansasii may cause cervical lymphadenitis, dermatitis, osteomyelitis, and arthritis. Disseminated infection occurs most commonly in immunocompromised patients (10). The organism can be identified in the laboratory on the basis of pigment and biochemical studies: M. kansasii is usually photochromogenic (rare isolates may be nonpigmented or scotochromogenic), and niacin accumulation is thought to be uniformly negative for this species. However, we recently isolated niacin-producing isolates of M. kansasii from three of our patients with compromised immune function, one at the University of Pennsylvania and two at the University of Cincinnati (two patients had respiratory infections, and one patient had a perirectal abscess). Case 1 (University of Pennsylvania). A 34-year-old black man, known to be positive for human immunodeficiency virus (HIV) antibody since August 1988, presented in September 1989 with a cough productive of blood-streaked sputum, increasing shortness of breath, pleuritic chest pain, and low-grade fevers. Diffuse interstitial bilateral infiltrates were observed on the chest radiograph. Bronchial washings showed many acid-fast bacilli by fluorochrome and Kinyoun staining and Pneumocystis carinii on silver staining. He was treated with isoniazid (INH), rifampin, and ethambutol for mycobacterial infection and cotrimoxazole and methylprednisolone for pneumocystis infection, with clinical improvement. A follow-up chest radiograph showed cavitation of the left upper lung infiltrate, with resolving interstitial infiltrates. He improved clinically and was discharged after 3 weeks of treatment for P. cannii pneumonia with zidovudine, INH, rifampin, and ethambutol. The isolated Mycobacterium sp. was subsequently identified as niacin-positive M. kansasii. After 1 year of treatment for M. kansasii pneumonia, his left apical lung cavity resolved and his antituberculous therapy was discontinued. Case 2 (University of Cincinnati). A 37-year-old white man who had been HIV positive for several years developed a

Tentative evidence of AIDS-associated biotype of Mycobacterium kansasii

“…Since the first description of human diseases due to M. kansasii, many cases have been reported, and in various areas of the United States, this species has long been the most frequently isolated mycobacterial species other than tuberculosis. The AIDS epidemic has changed the scenery, favoring the M. avium-M. intracellulare complex, but M. kansasii continues to be isolated, often in association with AIDS (3,9).…”

Comparison of a Novel Regimen of Rifapentine, Tedizolid, and Minocycline with Standard Regimens for Treatment of Pulmonary Mycobacterium kansasii

“…T he global incidence of pulmonary Mycobacterium kansasii has been increasing (1)(2)(3)(4)(5). Since chronic pneumonia caused by M. kansasii shares many clinical aspects with tuberculosis (TB) caused by Mycobacterium tuberculosis, it is not surprising that the American Thoracic Society (ATS) recommendation for treatment is similar to that for TB: a daily combination of isoniazid (300 mg/day), rifampin (600 mg/day), and ethambutol (15 mg/kg of body weight/day) for at least 12 months after sputum culture conversion (SCC) (6)(7)(8)(9)(10).…”