Spoligotyping of multidrug-resistant <I>Mycobacterium tuberculosis</I> isolates in Ethiopia

Abstract

St Peter Tuberculosis (TB) Specialized Hospital and the Aklilu Lemma Institute of Pathobiology, Addis Ababa, Ethiopia. To genotype multidrug-resistant tuberculosis (MDR-TB) isolates and assess the magnitude of their clustering. A total of 183 consecutive MDR-TB isolates collected between September 2009 and February 2012 were characterised using molecular typing. Prior to the study, the isolates were confirmed as MDR-TB using GenoType MTBDRplus. Recent transmission index was used to analyse the clusters. Spoligotyping identified 43 different patterns, of which 17 consisted of at least two isolates forming clusters, while 26 had only a single isolate. The most frequent patterns were spoligo international typing (SIT) number 21 and 149. Twenty-four patterns did not match existing patterns in the SpolDB4 database. The strains belonged to three lineages, the predominant lineages being Euro-American and Indo-Oceanic, each consisting of 65 isolates. High proportions (86%) of patients were infected with clustered strains, suggesting probable recent transmission of MDR-TB in the study area. The observation of cluster formation of the spoligotype patterns of MDR-TB isolates could suggest transmission of MDR-TB strains among the population, thus warranting further attention.