Buijtels, P.C.A.M.

Isolation of non-tuberculous mycobacteria at three rural settings in Zambia; a pilot study (Article)

2010-08-01T00:00:00Z

To assess the role of non-tuberculous mycobacteria (NTM) as a cause of tuberculosis-like diseases in Zambia, 167 chronically ill patients, hospitalized in three rural hospitals in Katete, Sesheke and Chilonga, were examined by microscopy and liquid culture for the presence of NTM. The percentages of patients with a positive culture for Mycobacterium tuberculosis complex were similar in the three geographical locations (19-25%). In contrast, the percentage of NTM ranged from 78% in Katete and 65% in Sesheke to 21% in Chilonga. Furthermore, the distribution of NTM species was different at the three geographical sites. In seven patients, true NTM-associated disease was suspected: five with Mycobacterium lentiflavum and two with Mycobacterium intracellulare. Analysis of possible risk factors indicated that the OR for NTM culture-positive sputum was significantly higher for patients living in Katete and Sesheke. Female gender and chest X-ray appearances of tuberculosis were independently associated with NTM culture-positive sputum. NTM colonization and disease in hospitalized, chronically ill patients in rural Zambia appear to be common. © 2010 The Authors. Journal Compilation

Misdiagnosis of tuberculosis and the clinical relevance of non-tuberculous mycobacteria in Zambia (Article)

2010-05-01T00:00:00Z

Objective: To determine the accuracy of TB diagnosis of TB in Zambia in the era of increasing HIV prevalence. Methods: Sputum of the clinically diagnosed TB cases was additionally subjected to liquid culture and molecular identification. This study distinguished between TB cases confirmed by positive Mycobacterium tuberculosis (M. tuberculosis) cultures and mycobacterial disease caused by non-tuberculous mycobacteria (NTM). Results: Only 49% of the 173 presumptively diagnosed TB cases was M. tuberculosis cultured, while in 13% (22) cases, a combination of M. tuberculosis and NTM was found. In 18% of the patients only NTM were cultured. In 28%, no mycobacteria was cultivable. HIV positive status was correlated with the isolation of NTM (P <0.05). Conclusions: The diagnosis of tuberculosis based on symptoms, sputum smear and/or chest X-ray leads to significant numbers of false-positive TB cases in Zambia, most likely due to the increased prevalence of HIV. The role of NTM in tuberculosis-like disease also seems relevant to the false diagnosis of TB in Zambia.

Nontuberculous mycobacteria, Zambia (Article)

2009-02-01T00:00:00Z

Clinical relevance of nontuberculous mycobacteria (NTM) isolated from 180 chronically ill patients and 385 healthy controls in Zambia was evaluated to examine the contribution of these isolates to tuberculosis (TB)-like disease. The proportion of NTM-positive sputum samples was significantly higher in the patient group than in controls; 11% and 6%, respectively (p<0.05). NTM-associated lung disease was diagnosed for 1 patient, and a probable diagnosis was made for 3 patients. NTM-positive patients and controls were more likely to report vomiting and diarrhea and were more frequently underweight than the NTM-negative patients and controls. Chest radiographs of NTM-positive patients showed deviations consistent with TB more frequently than those of controls. The most frequently isolated NTM was Mycobacterium avium complex. Multiple, not previously identified mycobacteria (55 of 171 NTM) were isolated from both groups. NTM probably play an important role in the etiology of TB-like diseases in Zambia.

Rapid identification of mycobacteria by Raman spectroscopy (Article)

2008-03-01T00:00:00Z

A number of rapid identification methods have been developed to improve the accuracy for diagnosis of tuberculosis and to speed up the presumptive identification of Mycobacterium species. Most of these methods have been validated for a limited group of microorganisms only. Here, Raman spectroscopy was compared to 16S rRNA sequencing for the identification of Mycobacterium tuberculosis complex strains and the most frequently found strains of nontuberculous mycobacteria (NTM). A total of 63 strains, belonging to eight distinct species, were analyzed. The sensitivity of Raman spectroscopy for the identification of Mycobacterium species was 95.2%. All M. tuberculosis strains were correctly identified (7 of 7; 100%), as were 54 of 57 NTM strains (94%). The differentiation between M. tuberculosis and NTM was invariably correct for all strains. Moreover, the reproducibility of Raman spectroscopy was evaluated for killed mycobacteria (by heat and formalin) versus viable mycobacteria. The spectra of the heat-inactivated bacteria showed minimal differences compared to the spectra of viable mycobacteria. Therefore, the identification of mycobacteria appears possible without biosafety level 3 precautions. Raman spectroscopy provides a novel answer to the need for rapid species identification of cultured mycobacteria in a clinical diagnostic setting. Copyright

Clinical Relevance of Non-Tuberculous Mycobacteria in Zambia (Doctoral Thesis)

2007-11-21T00:00:00Z

Tuberculosis, especially due to the high prevalence of HIV, remains a problem of large dimension in Africa and Mycobacterium tuberculosis is the most important causative agent. However, it is known that in developed countries also nontuberculous mycobacteria (NTM) play a significant role in the aetiology of tuberculosis-like syndromes, especially in HIV-positive patients. In Africa, the contribution of NTM to the problem of tuberculosis has hardly been examined. Southern Africa is the most affected sub-region in Africa concerning HIV/AIDS, where HIV prevalence rates have stabilized at high levels, exceeding 25% in some countries, while in other African countries, the epidemic is still growing. In Zambia the estimated adult (15-49 yrs) prevalence of HIV/AIDS amounted 13.5-20% in 2003 (61). NTM disease was one of the major AIDS-defining diseases in industrialized countries before the era of highly active antiretroviral therapy (HAART). Such infections have been thought to be less frequent in sub-Saharan Africa, but with the remaining doubt that the unavailability of the laboratory facilities and sophisticated radiological tools required to diagnose such disease may lead to underestimating of their true frequency (9,12,24,27,37,41,47). Whereas an international prospective study showed that NTM prevalence for disease was five to 10-fold lower in Kenya than in the United States of America or Northern Europe (24), a few hospital-based studies have reported a different prevalence for disease than reported in Kenya (9,12,27,37,41,47). For an overview of the literature on prevalence/incidence rates of colonization/infection/disease of NTM in Africa see Table 1 in the introduction of this thesis. Because the clinical relevance of the isolation of NTM in HIV-positive as well as in HIV-negative patients in Africa may be underestimated in this study, the meaning of NTM was examined in more detail in Zambia.

Isolation of nontuberculous mycobacteria in Zambia: eight case reports. (Article)

2005-12-01T00:00:00Z

The isolation of nontuberculous mycobacteria (NTM) raises the question of their clinical significance, especially in an African setting. We found a high percentage of NTM isolated from various specimens, including ones that are normally sterile, among 213 patients in Zambia. Because tuberculosis can affect all parts of the body, we decided to include patients who had signs and symptoms in any part of the body for more than 2 weeks. Most patients had tractus respiratorius (80%) and tractus digestivus (10%) symptoms. During three consecutive days, sputum was collected and two separate sputum specimens were cultured for mycobacteria. Depending on the clinical picture, pleural effusion, ascites, abscess material, or enlarged lymph nodes were also cultured for mycobacteria. A specimen from one sterile body site was collected from 25 patients (60% human immunodeficiency virus [HIV] positive). NTM were isolated from 8 of these 25 specimens. Mycobacterium lentiflavum was isolated from four patients, and Mycobacterium goodii was isolated from one patient. In order to exclude the possibility of laboratory cross-contamination, a novel amplified fragment length polymorphism DNA typing method for M. lentiflavum was developed. Genetic variation was detected, rendering the likelihood of laboratory contamination unlikely. Clinically relevant infection due to NTM occurs in both HIV-positive and HIV-negative patients in Zambia, and their clinical impact seems to be underestimated. This is the first report of M. lentiflavum and M. goodii infections in Africa.