Rapid identification of mycobacterium tuberculosis complex from Bactec 12B broth cultures originating from non-respiratory secretion specimens: comparison between Accuprobe and in-house polymerase chain reaction.
The rapid identification of Mycobacterium tuberculosis complex from 161 consecutive positive Bactec 12B cultures originated from non-respiratory secretion specimens was evaluated by comparing Accuprobe and an in-house polymerase chain reaction method. Using conventional biochemical method as the gold standard, 85.7% of the isolates (n = 138) were identified as Mycobacterium tuberculosis. The sensitivities of Accuprobe and the in-house-polymerase chain reaction method in identifying Mycobacterium tuberculosis complex were 92.0% (127/138) and 93.5% (129/138), respectively. Specificities of both methods being 87.0% (20/23 for both tests). Using a batch system of performing identification once weekly, the average turnaround time for Accuprobe, from the time of primary inoculation, was 27 days, which was comparable with that of in-house polymerase chain reaction, which was 29 days. The average time required for a confirmatory result based on conventional biochemical identification method was 84 days. The estimated reagent cost of in-house polymerase chain reaction was only one-fifth of that of Accuprobe. Therefore, the choice of methodology will depend on the individual laboratory's availability of resources and clinical demand. In the event of discrepant results between rapid identification methods and conventional methods, histological examination and clinical assessment can provide guidance as to the nature of the infection.
Hui
M
M
Department of Microbiology, the Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories. mamiehui@cuhk.edu.hk
Cheung
S W
SW
Chan
C Y
CY
Cheng
A F
AF
D001431:Bacteriological Techniques / Q000191:economics / Q000379:methods; D003365:Costs and Cost Analysis; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D009693:Nucleic Acid Hybridization / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000191:economics / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014376:Tuberculosis / Q000175:diagnosis*
D003470:Culture Media; D004269:DNA, Bacterial