[Assessment of the Amplicor PCR for the detection of Mycobacterium tuberculosis in smear negative respiratory and non respiratory specimens: a retrospective analysis].
BACKGROUND
Commercial polymerase chain reaction (PCR) kits are widely accepted for analysis of smear positive respiratory specimens, but the sensitivity is variable for smear negative ones.


OBJECTIVE
To assess the PCR method usefulness in smear negative respiratory and non respiratory specimens.


METHODS
We compared the PCR results (AMPLICOR MTB test, Roche) of 235 specimens subjected to culture in Loewenstein-Jensen agar (as the gold standard).


RESULTS
181 (76%) were respiratory and 54 (24%) extra-respiratory specimens. The sensitivity was 88%) and 50%>, respectively, specificity and PPV was 100%> in both cases. NPV was 99.4%> in respiratory specimens and 96.1% in non-respiratory specimens.


CONCLUSIONS
The good performance of this PCR in smear negative respiratory specimens allows the clinician to take decisions based on the result of this exam. In extra-respiratory specimens the contribution is important only when the PCR result is positive.
Selman
Carolina B
CB
Laboratorio de Biología Molecular, Departamento de Laboratorios Clínicos, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. c.selmanbravo@gmail.com
Poggi
Helena M
HM
Román
Juan C
JC
García
Patricia C
PC
Lagos
Marcela L
ML
D004269:DNA, Bacterial / Q000032:analysis*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis*
D004269:DNA, Bacterial