| Abstract: | Tuberculosis is one of the important public health problems in Egypt. However, limited information on the Mycobacterium tuberculosis genotypes circulating in Egypt is available. A total of 151 M. tuberculosis strains were characterized by spoligotyping. The results revealed that 74.8% of M. tuberculosis isolates grouped into 13 different clusters, while 25.2% had unique spoligotype patterns. Comparison with an international spoligotyping database (the SITVIT2 database) showed that types SIT53 (T1 variant) and SIT54 (Manu2 variant) were the most common types between cluster groups. In addition, new shared types SIT2977, SIT2978, and SIT2979 were observed. The results identified for the first time an unusually high proportion of ancestral Manu strains of M. tuberculosis from patients in Egypt. The percentage of the Manu clade in this study (27.15%) was significantly higher than its overall representation of 0.4% in the SITVIT2 database. We show that in Egypt tuberculosis is caused by a predominant M. tuberculosis genotype belonging to the ancestral Manu lineage which could be a missing link in the split between ancestral and modern tubercle bacilli during the evolution of M. tuberculosis.Despite the availability of antituberculosis (anti-TB) drugs, the disease burden of human TB remains a very serious and widespread public health problem. Many of the 22 countries most affected by human TB identified by the World Health Organization (WHO) are developing countries (11). Although Egypt is not on the WHO list of 22 high-TB-burden countries, it is considered one of the high-burden countries in WHO''s Eastern Mediterranean region, where TB constitutes the second most important public health problem after schistosomiasis (21). Every year, the National Tuberculosis Control Program of the Ministry of Health and Population (MOHP) registers over 12,000 new TB patients; more than 50% of the cases are sputum smear-positive pulmonary TB. On the basis of an annual risk of infection of 0.32%, it is estimated that about 8,000 people receive a diagnosis of TB at facilities other than those of MOHP (25).In the context described above, it is important to have a precise picture of the predominant and emerging Mycobacterium tuberculosis clones in Egypt, in order to have a first snapshot of the epidemiology of TB. The advent of molecular typing methods has given a new boost to epidemiological studies of TB in recent years (3); the most commonly used methods are IS6110-based restriction fragment length polymorphism (RFLP) (IS6110-RFLP) and spoligotyping (12, 22). As opposed to IS6110-RFLP, which was considered the “gold standard” for the genotyping of M. tuberculosis in the early 1990s (22) and which is time-consuming and labor-intensive and requires large amounts of highly purified DNA, PCR-based spoligotyping avoids the problems associated with the slow growth of these bacteria, thereby offering the possibility of the rapid recognition of outbreaks (2, 4, 12). The clinical usefulness of spoligotyping is determined by its rapidity both in detecting the causative bacteria and in providing epidemiological information on strain identities (12). Spoligotyping, which allows determination of the phylogeographical specificity of circulating clades of tubercle bacilli, is also useful for population-based studies (4, 10). Recent data from international spoligotyping studies have identified a growing number of important clades or genogroups, further facilitating the study of the spread of the disease due to human migratory movements (4, 8, 9, 17). To date, there is very limited genotyping information on the M. tuberculosis strains circulating in Egypt. The SITVIT2 database, which is an updated version of the previously released SpolDB4 database (4; available online at http://www.pasteur-guadeloupe.fr:8081/SITVITDemo), showed very little information on the isolates circulating in Egypt, with only 79 of 69,000 clinical isolates, i.e., 0.1% of the total recruitment. The aim of this study was to identify the predominant international spoligotypes responsible for the transmission and prevalence of TB in Egypt. The spoligotypes obtained were further compared with those in an updated version of the international database named SITVIT2. |
