Usefulness of a new mycobacteriophage-based technique for rapid diagnosis of pulmonary tuberculosis.
A new mycobacteriophage-based technique (PhageTek MB) was compared with standard culture and staining techniques for diagnosis of pulmonary tuberculosis. A total of 2,048 respiratory specimens from 1,466 patients collected from February 2000 to March 2001 were studied by both (i) conventional methods (direct microscopic examination [auramine-rhodamine fluorochrome], and culture in BacT/ALERT 3D and solid media) and (ii) the PhageTek MB assay. This phenotypic test utilizes specific mycobacteriophages to detect the presence of live Mycobacterium tuberculosis complex organisms within a decontaminated clinical sample. Overall, 205 (10%) specimens were positive for mycobacteria (134 patients): 144 (70.2%) M. tuberculosis isolates and 61 (29.8%) nontuberculous mycobacterium isolates (30 Mycobacterium kansasii, 12 Mycobacterium xenopi, 9 Mycobacterium gordonae, 7 Mycobacterium avium complex, 2 Mycobacterium chelonae, and 1 Mycobacterium fortuitum isolate). PhageTek MB was more likely to give a positive result with specimens in which high numbers of acid-fast bacilli were observed on the smear. The sensitivity, specificity, and positive and negative predictive values of this mycobacteriophage-based technique versus culture for M. tuberculosis were 58.3, 99.1, 83.2, and 96.9%, respectively. PhageTek MB is a rapid (48-h), specific, safe, and easy-to-perform test. According to the prevalence of the disease in the population studied, the test would require improved sensitivity in order to be used as a screening test for routine diagnosis of respiratory tuberculosis in our setting.
Alcaide
Fernando
F
Servei de Microbiologia, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain. falcaide@csub.scs.es
Galí
Nuria
N
Domínguez
José
J
Berlanga
Pilar
P
Blanco
Silvia
S
Orús
Pilar
P
Martín
Rogelio
R
D015169:Colony Count, Microbial; D003470:Culture Media; D006801:Humans; D009160:Mycobacteriophages / Q000254:growth & development*; D009169:Mycobacterium tuberculosis / Q000254:growth & development / Q000302:isolation & purification* / Q000821:virology; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology; D010948:Viral Plaque Assay
D003470:Culture Media; D011933:Reagent Kits, Diagnostic