First insight into the genetic diversity of Mycobacterium tuberculosis strains from patients in Duhok, Iraq

Genetic diversity of Mycobacterium tuberculosis Central Asian Strain isolates from Nepal and comparison with neighboring countries

BACKGROUND

Multidrug-resistant tuberculosis (MDR-TB) is an emerging threat for successful tuberculosis control worldwide. Central Asian Strain (CAS) has been reported as one of the dominant families contributing to MDR-TB in South Asia including Nepal, India and Pakistan. The aim of this study was to better understand the genetic characteristics of MDR-TB CAS family isolates circulating in Nepal and compare the results with neighboring countries.

METHODS

A total of 145 MDR-TB CAS family isolates collected in Nepal from 2008 to 2013 were analyzed by spoligotyping and mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) analysis. In addition, we compared these data with published data from India and Pakistan to investigate a possible epidemiological link via construction of a minimum spanning tree (MST).

RESULTS

Spoligotyping analysis exhibited CAS1_Delhi SIT26 (n=60) as the predominant lineage among the MDR-TB CAS family in all three countries. However, the combined analysis with spoligotyping and MIRU-VNTR further discriminated 60 isolates into 49 different types and 5 clusters. Each cluster was composed of 14 isolates with a clustering rate of 23.3%, suggesting ongoing transmissions. Based on MST data from neighboring countries, we elucidated an evolutionary relationship between the two countries, Nepal and India, which could be explained by their open border.

CONCLUSION

This study identified the evolutionary relationships among MDR-TB CAS1_Delhi subfamily isolates from Nepal and those from neighboring countries.

Spoligotyping with pncA sequencing strategy conferring the transmission of multidrug-resistant tuberculosis in Egypt

Background

This study explored the genetic diversity of Mycobacterium tuberculosis isolates in Egypt by spoligotyping in combination with pncA gene sequencing, spoNC.

Methods

First, isolates were selected from 400 isolates positive for M. tuberculosis that referred to Central Labs Ministry of Health and then were subjected to the study analyses.

Results

Twenty one isolates were found to be multidrug resistant (MDR) and 29 isolates were sensitive for isonizide (INH) and rifampicine (RIF) after testing by phenotypic drug susceptibility testing (DST) and Mycobacteria Growth Indicator Tube (MGIT). Spoligotyping yielded 45 patterns belonging to seven families that previously reported in neighboring countries such as Iraq, Syria, Iran, and Turkey. While four isolates were orphans.

Conclusion

Application of spoNC on obtained spoligotype patterns enhances to reduce the clustering rate. Bejing family the predominant (34%) were subdivided by pncA sequence into three sensitive DST pncA wild type, three MDR-DST isolates showing cys14Arg mutation in pncA, two sensitive DST isolates with pncA Gly97Asp mutation, and three sensitive DST pncAVal128Gly mutation. The next most common CASI_DELHI family (16%) were subdivided by pncA sequencing into CASI_DELHI (st 381, MDR) including two pncA silent mutation ser65ser (tcc > tct) and CASI_DELHI (st26, sensitive) which included six pncA (wild-type) results, and Latin-American-Mediterranean 6 family (6%) all had PncA Gly97Asp mutation. We concluded that spoNC provides good snap shot for MDR surveillance and its country origin and performs early identification of outbreaks in Egypt.

First insight into the genetic population structure of Mycobacterium tuberculosis isolated from pulmonary tuberculosis patients in Egypt

The present study aimed to assess the population structure of Mycobacterium tuberculosis (MTB) isolates from Egypt. A total of 230 MTB isolates were analysed using spoligotyping, large sequence polymorphism (LSPs), mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing and multi-locus sequence typing (MLST). The majority of isolates (93.0%) belonged to lineage 4, including 44.3, 13.4 and 10.8% of the ill-defined T clade, LAM and Haarlem families, respectively, and lineage 3 was identified in 7.0% of the isolates. MIRU-VNTRs typing allowed efficient discrimination of the spoligotype-defined clusters, including spoligo-international types (SIT) 53, 34, and 4, into 56 patterns, including 13 clusters and 43 unique patterns. A new SNP at position 311614 was identified in all six isolates to form the biggest MIRU-VNTR cluster, which suggested a recent clonal expansion. This SNP could possibly be used as a genetic marker for robust discriminations of Egyptian MTB isolates belonging to SIT53. The combination of spoligotyping, 12 MIRU-VNTRs loci and MLST provided insight into the genetic diversity and transmission dynamics of the Egyptian MTB genotypes and could be a key to implementation of effective control measures by public health authorities.

Estimation of Recent Transmission of Mycobacterium Tuberculosis Strains among Iranian and Afghan Immigrants: A Cluster-Based Study

BACKGROUND

Iran has extended borders with high-TB burden countries (Afghanistan and Pakistan) and immigrations of these populations influences TB distribution in the region and threatens the control strategies. The aim of this study was to evaluate the extent of recent TB transmission among Iranian and Afghan cases.

MATERIALS AND METHODS

Spoligotyping and 15-locus variable number tandem repeat (VNTR) typing were applied to genotype 102 MTB isolates (2009 to 2010). Phylogenetic relationships were analysed by two methods: a cluster-graph method and a minimum spanning tree (MST) method. Furthermore, evaluation of recent TB transmission was assessed with three indices including, RTIn, RTIn-1 and TMI.

RESULTS

Using molecular typing, 35 different spoligotypes were detected among the studied isolates. Seventy seven cases (75.4%) were distributed into 10 clusters and the remaining 25 (24.5%) isolates had a unique pattern. The cluster sizes also ranged from 2 to 21 isolates. The most frequent spoligotype in our populations belong to Haarlem (n=30, 29.4%) followed by CAS (n= 29, 28.4%) and Beijing (n=16, 15.6%) lineages. The used indices give the following values: RTIn = 0.75, RTIn-1 = 0.65 and TMI = 0.24.

CONCLUSION

The low rate of TB transmission in our findings (24%) showed that the mode of TB transmission in Iran is mostly associated with reactivation of a previous TB infection and that recently a transmitted disease has a minor role. However, the increasing incidence of the intra-community transmission in recent years highlights the need for establishing new strategies for control of TB.