Identification and differentiation of Mycobacterium avium & M. intracellulare by PCR- RFLP assay using the groES gene .

Aravindhan, V.; Sulochana, S.; Narayanan, S.; Paramasivam, C.N.; Narayanan, P.R.

Indian Journal of Medical Research; 2007; 126; 575-579.

Background & objectives : We report a new polymerase chain reaction (PCR) – restriction fragment length polymorphism (RFLP) assay using mycobacterial groES as a target to identify Mycobacterium avium and M. intracellulare in clinical samples.

Methods : The assay was standardized using M. avium and M. intracellulare standard strains obtained from ATCC and was tested with 45 M. avium - M. intracellulare complex (MAC) clinical isolates (Of which 31 were from HIV + individuals). The standard and clinical strains were typed with HPLC based mycolic acid fingerprinting.

Results : Three polymorphisms ( BamHI, BstNI and HgaI ) were identified for inter-species differentiation among standard strains; of which, only HgaI was found to be useful in clinical isolates. Of the 45 isolates, 25 were M. avium and 20 were M. intracelluare . MAC isolates, which could not be differentiated by HPLC analysis, were also typed by this method.

Interpretation & conclusions : The use of mycobacterial groES as a PCR-RFLP target for M. avium and M. intracellulare is a simple and rapid method that can complement HPLC in their differentiation.

Keywords : groES - HPLC - MAC - Mycobacterium avium - M. intracellulare - PCR-RFLP

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