Gene probes versus classical methods in the identification of mycobacteria.
OBJECTIVE
The emergence of tuberculosis/HIV co-infection and the increase in the number of cases of infection with nontuberculous mycobacteria (NTM) require rapid laboratory test results in the isolation and identification of mycobacteria. The objective of this study was to evaluate the identification of mycobacteria by means of gene probes in comparison with that obtained using classical biochemical methods.


METHODS
Between 2002 and 2004, 178 mycobacterial cultures, all testing positive for acid-fast bacilli, were analyzed. Samples were obtained from clinical specimens of patients with respiratory symptoms or with clinical suspicion of pulmonary tuberculosis/mycobacteriosis who were treated in the greater metropolitan area of Santos.


RESULTS
The gene probe identified 137 samples (77%) as Mycobacterium tuberculosis complex and 41 (23%) as NTM. Discordant results between the methods (3%) were obtained only in the year of implementation (2002). When comparing the methods, the sensitivity, specificity, positive predictive value and negative predictive value of the gene probe method were 98%, 93%, 98% and 93%, respectively.


CONCLUSIONS
Despite the cost, the identification of mycobacteria using the molecular technique is faster: maximum 3 h vs. 28-30 days for classical methods. The use of gene probes is a validated molecular technique. It is fast, easy to use and readily available on the market. It has high specificity and sensitivity, which justifies its implementation and routine use in referral laboratories, since it facilitates the diagnosis providing agile clinical interventions.
Coelho
Andréa Gobetti Vieira
AG
Laboratório Regional Santos, Instituto Adolfo Lutz, Santos, SP, Brasil. dea_gobetti@hotmail.com
Zamarioli
Liliana Aparecida
LA
Reis
Clemira Martins Pereira Vidal
CM
Nascimento
Ana Carolina Chiou
AC
Rodrigues
Juliana Dos Santos
Jdos S
D001431:Bacteriological Techniques / Q000592:standards*; D015342:DNA Probes / Q000592:standards*; D015658:HIV Infections / Q000150:complications; D006801:Humans; D015336:Molecular Probe Techniques / Q000592:standards*; D009161:Mycobacterium / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018088:Tuberculosis, Multidrug-Resistant / Q000150:complications / Q000175:diagnosis; D014397:Tuberculosis, Pulmonary / Q000150:complications / Q000175:diagnosis*
D015342:DNA Probes