Genetic diversity of Mycobacterium tuberculosis complex strains isolated from patients with pulmonary tuberculosis in Anambra State, Nigeria

• Main Authors: Gertrude N Uzoewulu, Lovett Lawson, Ibeh S Nnanna, Nalin Rastogi, Madhu Goyal
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2016-01-01
• Series: International Journal of Mycobacteriology
• Subjects: Exact tandem repeat; Mycobacterium tuberculosis; Nigeria; Spoligotyping; Tuberculosis; Variable number of tandem repeats
• Online Access: http://www.ijmyco.org/article.asp?issn=2212-5531;year=2016;volume=5;issue=1;spage=74;epage=79;aulast=Uzoewulu

In this study, we analyzed Mycobacterium tuberculosis complex (MTC) genetic diversity in Anambra State, Nigeria based on spoligotyping followed by 5-loci exact tandem repeats (ETRs). Spoligotyping of 180 MTC strains isolated in 2009–2011 from pulmonary tuberculosis (TB) patients led to a total of 31 distinct patterns. A comparison with the SITVIT2 international database showed that all the 31 patterns could be classified as Shared-types (SITs) in this database; briefly, 26/31 SITs (n =174 isolates) matched a preexisting shared-type in the database, whereas 5/31 SITs (n =6 isolates) were newly created due to 2 or more strains belonging to an identical new pattern within this study (SIT3396) or after a match with an orphan in the database (SIT3397, SIT3398, SIT3399 and SIT3400). A total of 18/31 SITs containing 167 or 92.8% isolates were clustered within this study (2–89 isolates per cluster) while 13/31 SITs contained unique strains. Using VNTR typing, a total of 36 distinct patterns were identified; 27 patterns (n =157 isolates) matched a pattern already reported in the SITVIT2 database. Combination of both the methods generated 47 combined patterns for the 180 strains: 17 belonged to clustered isolates (n =127 isolates or 70.5%) while 30 corresponded to as many unique strains (note 23 strains could not be typed using 5-loci ETRs). No correlation was found between the spoligotyping pattern and the HIV status of the patient or drug sensitivity of the strain. This study showed that the LAM10-CAM prototype SIT61 accounted for highest number of isolates (n =89) in Anambra State, showing its relative contribution to the TB burden in the study.