MOLECULAR CHARACTERIZATION OF MYCOBACTERIUM-AVIUM COMPLEX ISOLATES FROM CARIBBEAN PATIENTS BY DT1 DT6-PCR, NONRADIOACTIVE SOUTHERN HYBRIDIZATION, AND THE ACCUPROBE SYSTEM/
C. Sola et al., MOLECULAR CHARACTERIZATION OF MYCOBACTERIUM-AVIUM COMPLEX ISOLATES FROM CARIBBEAN PATIENTS BY DT1 DT6-PCR, NONRADIOACTIVE SOUTHERN HYBRIDIZATION, AND THE ACCUPROBE SYSTEM/, Current microbiology, 33(6), 1996, pp. 352-358
A genetic fingerprinting analysis of Caribbean isolates of M. avium co
mplex (MAC) from AIDS patients by a Southern blotting technique after
Pst1 digestion with nonradioactive DNA probes coding for single-copy s
equences DT1 and DT6 was performed. In parallel, a selective amplifica
tion of a 187-bp fragment within the DT6 sequence with AV6/AV7 primers
for Mycobacterium avium and of a 665-bp fragment within the DT1 seque
nce of M. intracellulare with the IN38/IN41 primers was also performed
, and the molecular speciation with these two methods was compared wit
h results obtained with DNA probes of the Accuprobe system. 66 strains
investigated comprised 31 international reference isolates of MAC bel
onging to serovars 1-28 and 42-44, and 35 clinical isolates including
24 strains from Caribbean AIDS patients. 91.43% of the clinical isolat
es tested gave concordant data with the DT1/DT6 Southern hybridization
and PCR as compared with 74.28% for PCR and Accuprobe, and 71.43% for
Accuprobe and Southern hybridization. Our results corroborated previo
us findings showing that the DT1 probe was specific for M. intracellul
are, whereas the DT6 probe was specific for M. avium (reference serova
rs 2 and 3 probed positive both with DT1 and DT6 probes). Contrary to
DT1 probe, which did not reveal sufficient polymorphism to discriminat
e between MAC isolates, DT6 probe showed an interesting polymorphism g
iving four distinct clusters. Three clusters corresponded to profiles
previously reported for reference and/or clinical isolates; however, a
fourth cluster was discovered in five Caribbean isolates from four AI
DS patients that did not correspond to previously published genetic pa
tterns. When probed with the insertion sequence IS1245, this cluster r
etained its homogeneity.