The genotypic population structure of Mycobacterium tuberculosis complex from Moroccan patients reveals a predominance of Euro-American lineages.
BACKGROUND
Tuberculosis (TB) remains a major health problem in Morocco. Characterization of circulating Mycobacterium tuberculosis genotypic lineages, important to understand the dynamic of the disease, was hereby addressed for the first time at a national level.


RESULTS
Spoligotyping was performed on a panel of 592 M. tuberculosis complex strains covering a 2-year period (2004-2006). It identified 129 patterns: 105 (n = 568 strains) corresponded to a SIT number in the SITVIT2 database, while 24 patterns were labeled as orphan. A total of 523 (88.3%) strains were clustered vs. 69 or 11.7% unclustered. Classification of strains within 3 large phylogenetical groups was as follows: group 1- ancestral/TbD1+/PGG1 (EAI, Bovis, Africanum), group 2- modern/TbD1-/PGG1 group (Beijing, CAS), group 3- evolutionary recent/TbD1-/PGG2/3 (Haarlem, X, S, T, LAM; alternatively designated as the Euro-American lineage). As opposed to group 3 strains (namely LAM, Haarlem, and T) that predominated (86.5% of all isolates), 6 strains belonged to group 2 (Beijing n = 5, CAS n = 1), and 3 strains (BOV_1 n = 2, BOV_4-CAPRAE) belonged to ancestral group 1 (EAI and AFRI lineage strains were absent). 12-loci MIRU-VNTR typing of the Casablanca subgroup (n = 114 strains) identified 71 patterns: 48 MITs and 23 orphan patterns; it allowed to reduce the clustering rate from 72.8% to 29.8% and the recent transmission rate from 64% to 20.2%.


CONCLUSIONS
The M. tuberculosis population structure in Morocco is highly homogeneous, and is characterized by the predominance of the Euro-American lineages, namely LAM, Haarlem, and T, which belong to the "evolutionary recent" TbD1-/PGG2/3 phylogenetic group. The combination of spoligotyping and MIRUs decreased the clustering rate significantly, and should now be systematically applied in larger studies. The methods used in this study appear well suited to monitor the M. tuberculosis population structure for an enhanced TB management program in Morocco.
National Tuberculosis Reference Laboratory, National Institute of Hygiene, Rabat, Morocco.
Ouafae
O
Lahlou
Julie
J
Millet
Imane
I
Chaoui
Radia
R
Sabouni
Abdelkarim
A
Filali-Maltouf
Mohammed
M
Akrim
Mohammed
M
El Mzibri
Nalin
N
Rastogi
Rajae
R
El Aouad
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D005838:Genotype; D006801:Humans; D008875:Middle Aged; D009018:Morocco / Q000453:epidemiology; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D010802:Phylogeny; D014376:Tuberculosis / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D055815:Young Adult
D004269:DNA, Bacterial