Diagnosis of mycobacterial infections based on acid-fast bacilli test and bacterial growth time and implications on treatment and disease outcome.

Background: The establishment of therapeutic regimens for mycobacteriosis depends on the accurate identificationof Mycobacterium species, and misdiagnosis can result in inappropriate treatment and increased mortality of patients.Differential diagnosis among Mycobacterium species has been made by conventional phenotypic and biochemicaltests after a long culture period. Specialized molecular diagnostics of mycobacteria allows rapid detection and speciesidentification; however, such tests are not available in public health programs. Our aim was to demonstrate the clinicalimplications of erroneous diagnosis by performing molecular genotyping of mycobacterial infections in patients thatwere diagnosed based on symptoms, culture and bacilloscopy.Methods: Culture samples of mycobacterial infections from 55 patients clinically diagnosed as tuberculosis in 2013and 2014, based on conventional methods, were identified by PCR -RFLP and results are discussed.Results: We have confirmed 35 (63.6 %) positive samples as M. tuberculosis, but 18 (32.7 %) were identified asnon-tuberculous mycobacteria (M. avium type 1, M. avium type 2, M. kansasii type 1 type 1, M. mucogenicum, M.chelonae, M. terrae type 3, and 1 unknown RFLP pattern) and two were negative. Regarding clinical diagnosis,61.8 % (34/55) was classified as pulmonary tuberculosis. It is important to emphasize that 36.4 % (20/55) of sampleswere misdiagnosed by conventional methods, and 11 (61.1 %) of the HIV positive patients (18/55) were NTMcoinfected.Conclusion: The identification of species in mycobacterial infections is essential for correct diagnosis and choice oftreatment regimen, and misdiagnosis by conventional tools can lead to chronic disease, increased resistance anddeath.Keywords: Mycobacteria, PCR-RFLP, Molecular Diagnosis

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