Multiplex PCR assay for simultaneous detection and differentiation of Mycobacterium tuberculosis, Mycobacterium avium complexes and other Mycobacterial species directly from clinical specimens.
OBJECTIVE
Polymerase chain reaction (PCR) is the most rapid and sensitive method for diagnosing mycobacterial infections and identifying the aetiological Mycobacterial species in order to administer the appropriate therapy and for better patient management.


RESULTS
Two hundred and thirty-five samples from 145 clinically suspected cases of tuberculosis were processed for the detection of Mycobacterial infections by ZN (Ziehl Neelsen) smear examination, L-J & BACTEC MGIT-960 culture and multiplex PCR tests. The multiplex PCR comprised of genus-specific primers targeting hsp65 gene, Mycobacterium tuberculosis complex-specific primer targeting cfp10 (Rv3875, esxB) region and Mycobacterium avium complex-specific primer pairs targeting 16S-23S Internal Transcribed Spacer sequences. The multiplex PCR developed had an analytical sensitivity of 10 fg (3-4 cells) of mycobacterial DNA. The multiplex PCR test showed the highest (77.24%) detection rate, while ZN smear examination had the lowest (20%) detection rate, which was bettered by L-J culture (34.4%) and BACTEC MGIT-960 culture (50.34%) methods. The mean isolation time for M. tuberculosis was 19.03 days in L-J culture and 8.7 days in BACTEC MGIT-960 culture. Using the multiplex PCR, we could establish M. tuberculosis + M. avium co-infection in 1.3% HIV-negative and 2.9% HIV-positive patients. The multiplex PCR was also highly useful in diagnosing mycobacteraemia in 38.09% HIV-positive and 15.38% HIV-negative cases.


CONCLUSIONS
The developed in-house multiplex PCR could identify and differentiate the M. tuberculosis and M. avium complexes from other Mycobacterial species directly from clinical specimens.


CONCLUSIONS
The triplex PCR developed by us could be used to detect and differentiate M. tuberculosis, M. avium and other mycobacteria in a single reaction tube.
Gopinath
K
K
Division of Clinical Microbiology, Department of Laboratory Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
Singh
S
S
D000293:Adolescent; D000328:Adult; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis* / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D005260:Female; D006679:HIV Seropositivity / Q000382:microbiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009164:Mycobacterium Infections / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology; D015269:Mycobacterium avium Complex / Q000235:genetics / Q000302:isolation & purification*; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D014376:Tuberculosis / Q000175:diagnosis; D055815:Young Adult
D017931:DNA Primers; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S