Evaluation of a commercial ligase chain reaction assay for the diagnosis of pulmonary and extra-pulmonary tuberculosis.
METHODS
Egas Moniz Hospital, Lisbon, Portugal.


OBJECTIVE
To evaluate the Ligase Chain Reaction (LCx) Mycobacterium tuberculosis Assay for the direct detection of M. tuberculosis complex in respiratory specimens after smear observation, and its suitability for non-respiratory clinical specimens.


METHODS
Analysis of 156 specimens collected from 123 patients with pulmonary tuberculosis and/or extrapulmonary involvement.


RESULTS
Among 93 pulmonary secretions and 63 extra-pulmonary samples and after resolution of discrepancies based on clinical and laboratory findings, two pulmonary samples from a patient with a diagnosis of sarcoidosis, four samples of cerebrospinal and one of seminal fluid were considered as false positives. Two tissue biopsy samples, one pericardial effusion and one pulmonary secretion from patients strongly suspected of having tuberculosis were considered as false negatives for the assay, without inhibition of amplification. All specimens yielding M. avium on culture were LCx negative.


CONCLUSIONS
The LCx Mycobacterium tuberculosis Assay was found to be useful for the rapid identification of M. tuberculosis complex in all types of specimens. It revealed a high specificity both in pulmonary and extrapulmonary products, and a sensitivity of 97% for the pulmonary secretions and of 75% for the extra-pulmonary specimens, independently of the bacilloscopy results.
Viveiros
M
M
Departamento de Microbiologia e Centro de Malaria e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Portugal. mviveiros@ihmt.unl.pt
Pinheiro
S
S
Moreira
P
P
Pacheco
T
T
Brum
L
L
D001706:Biopsy; D001826:Body Fluids / Q000382:microbiology*; D015897:Comorbidity; D003470:Culture Media; D003937:Diagnosis, Differential; D005069:Evaluation Studies as Topic; D005122:Exudates and Transudates / Q000382:microbiology*; D018023:HIV Seronegativity; D006679:HIV Seropositivity / Q000453:epidemiology; D006801:Humans; D008025:Ligases / Q000378:metabolism; D008198:Lymph Nodes / Q000382:microbiology / Q000473:pathology; D009169:Mycobacterium tuberculosis / Q000254:growth & development / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011174:Portugal; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis
D003470:Culture Media; D011933:Reagent Kits, Diagnostic; D008025:Ligases