Abstract
The main cause of pulmonary tuberculosis (TB) is infection with Mycobacterium tuberculosis (MTB). We aimed to evaluate the contribution of nontuberculous mycobacteria (NTM) to pulmonary disease in patients from the state of Rondônia using respiratory samples and epidemiological data from TB cases. Mycobacterium isolates were identified using a combination of conventional tests, polymerase chain reaction-based restriction enzyme analysis of hsp65 gene and hsp65 gene sequencing. Among the 1,812 cases suspected of having pulmonary TB, 444 yielded bacterial cultures, including 369 cases positive for MTB and 75 cases positive for NTM. Within the latter group, 14 species were identified as Mycobacterium abscessus, Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium intracellulare, Mycobacterium gilvum, Mycobacterium gordonae, Mycobacterium asiaticum, Mycobacterium tusciae, Mycobacterium porcinum, Mycobacterium novocastrense, Mycobacterium simiae, Mycobacterium szulgai, Mycobacterium phlei and Mycobacterium holsaticum and 13 isolates could not be identified at the species level. The majority of NTM cases were observed in Porto Velho and the relative frequency of NTM compared with MTB was highest in Ji-Paraná. In approximately half of the TB subjects with NTM, a second sample containing NTM was obtained, confirming this as the disease-causing agent. The most frequently observed NTM species were M. abscessus and M. avium and because the former species is resistant to many antibiotics and displays unsatisfactory cure rates, the implementation of rapid identification of mycobacterium species is of considerable importance.
Highlights
Outbreaks of nontuberculous Mycobacterium (NTM) infections are increasing worldwide (Wallace et al 1998) and in Brazil
The other 19 cases (46.7%) had positive cultures from either two (n = 12), three (n = 4), four (n = 2) or five (n = 1) consecutive samples and, according to the microbiological criteria defined by the American Thoracic Society (ATS), were suffering from lung disease caused by NTM
16.9% of the Mycobacterium isolates were NTM and from our data, we calculated the incidence of NTM in 2010 as 3.9/100,000 and 10.8/100,000 in Porto Velho and Ji-Paraná, respectively, which is higher than the incidence of NTM-induced pulmonary disease reported in other studies conducted in Brazil
Summary
Outbreaks of NTM infections are increasing worldwide (Wallace et al 1998) and in Brazil This was due to the HIV/AIDS pandemic, but now is apparently associated with surgery and cosmetic procedures due to the use of improperly sterilised equipment (MS 2008). Patient isolates - We performed a retrospective study using the laboratory data collected during routine processing of sputum samples obtained from individuals suspected of having pulmonary TB who were sent to the Central Laboratory of Public Health in RO (LACEN). The laboratory data included the number and type of specimens collected, site of isolation, number of positive cultures obtained from the same case, identification of bacterial species as determined by conventional identification methods and HIV status of the patient. This study was approved by the Ethical Committee of the Federal University of Rondônia (protocol 19/2007)
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