Micro-epidemic due to a new Mycobacterium tuberculosis strain among the homeless in Budapest, Hungary

In a retrospective study that included 66 homeless tuberculosis patients a local micro-epidemic was identified in the VIIIth district of Budapest with the highest tuberculosis incidence of the capital. Further molecular genetic characterization by IS 6110 fingerprinting, spoligotyping and mycobacterial inter-spread repetitive unit (MIRU) typing has shown that the observed micro-epidemic was due to a locally emerged, Budapest-specific lineage. The absence of infections with the more virulent Beijing genotype is also noteworthy. The findings indicate that tuberculosis control and prevention steps among the homeless need to be strengthened in Hungary.     

Zoonotic tuberculosis due to Mycobacterium bovis in developing countries.

The World Health Organization (WHO) estimates that human tuberculosis (TB) incidence and deaths for 1990 to 1999 will be 88 million and 30 million, respectively, with most cases in developing countries. Zoonotic TB (caused by Mycobacterium bovis) is present in animals in most developing countries where surveillance and control activities are often inadequate or unavailable; therefore, many epidemiologic and public health aspects of infection remain largely unknown. We review available information on zoonotic TB in developing countries, analyze risk factors that may play a role in the disease, review recent WHO activities, and recommend actions to assess the magnitude of the problem and control the disease in humans and animals.     

Molecular diversity of Mycobacterium tuberculosis isolates from patients with pulmonary tuberculosis in Sri Lanka

The strain diversity of 100 Mycobacterium tuberculosis isolates collected over a period of 18 months from tuberculosis (TB) cases in Sri Lanka was studied by spoligotyping. When compared to the international spoligotyping database, 43 spoligotype patterns were identified, of which 20 were previously described. The majority of isolates (72.45%) were clustered into major genetic group 1, and the most common spoligotype pattern belonged to the Beijing (ST1) strain family. All the Beijing strain isolates belonged to more recently evolved sublineages of M. tuberculosis. The characterization of Sri Lankan M. tuberculosis isolates by spoligotyping shows a heterogeneous pattern. The physical separation from the main Indian peninsula may be responsible for the different patterns observed between the two countries. An in-depth field study is needed to understand the spread and the true epidemiology of this infection.     

Pulmonary tuberculosis due to Mycobacterium bovis subsp. caprae in captive Siberian tiger

We report the first case of pulmonary tuberculosis caused by Mycobacterium bovis subsp. caprae in a captive Siberian tiger, an endangered feline. The pathogen was isolated from a tracheal aspirate obtained by bronchoscopy. This procedure provided a reliable in vivo diagnostic method in conjunction with conventional and molecular tests for the detection of mycobacteria.     

Subcutaneous abcesses due to Mycobacterium avium due to a reconstitution syndrome in AIDS patients

Clinical presentations of opportunistic infections in AIDS patients have dramatically changed since the introduction of HAART. The immune reconstitution syndrome (IRS) is typical of this change. The authors discuss the case of an AIDS female patient presenting with subcutaneous abcesses and abdominal lymph node enlargement due to Mycobacterium avium and occurring 10 weeks after initiation of HAART. This was related to the exacerbation of immune response against the bacteria that had previously infected the patient. Many cases of IRS involving M. avium have now been described, but cutaneous localisations remain infrequent. The treatment consists in HAART continuation associated with anti mycobacterial antibiotics and possibly anti inflammatory drugs.     

重庆市结核患者耐药结核杆菌embB306分子突变特征研究

目的 了解重庆结核杆菌的embB306突变特征,评价其作为诊断乙胺丁醇(ethambutol,EMB)耐药结核杆菌分子标记物的临床应用价值.方法 采用DNA测序方法分析重庆市结核患者痰中分离的51株EMB耐药结核杆菌和50株EMB敏感株的embB基因突变特征,与传统药敏实验进行诊断学试验评价embB306突变作为EMB耐药株分子标记物的临床应用价值.结果 embB306突变率在51株EMB耐药和50株敏感结核杆菌中分别为75.5%、6%;其中来自复治病例的EMB耐药菌株的embB306突变率是87.5%,高于来自初治病例的48.1%;embB306突变率随菌株耐药数量增加而升高,embB306在EMB耐药的耐多药菌株(Multidrug-Resistant Tuberculosis,MDR-TB)中的突变率高于EMB耐药的非MDR-TB和EMB敏感的MDR-TB的突变率;以embB306突变诊断EMB耐药菌株的诊断学试验评价主要指标为:灵敏度为66.7%;特异度为94.0%;准确度为80.2%;Youden指数为60.7%.结论embB306突变是重庆地区结核杆菌产生EMB耐药性的主要分子机制,且与耐药数量和治疗时间有关,其作为EMB耐药菌株诊断的分子标记物具有一定临床应用价值.     

MIRU-VNTR和Spoligotyping用于重庆地区210株儿童结核分枝杆菌临床分离株的基因分型

目的 评价间隔区寡核苷酸分型(Spoligotyping)和基于结核分枝杆菌散在分布数目可变串联重复序列分析(MIRU-VNTR)方法在重庆地区儿童结核病分子流行病学中的应用.方法 收集重庆地区210株儿童结核分枝杆菌(MTB)临床分离株,应用上述两种分型方法进行比较分析.结果 采用Spoligotyping分型方法,210株菌可分为2个基因群44种基因型,其中最大的1个基因群即北京家族(北京基因型)含有130株菌(61.90%).采用MIRU-VNTR分析发现24个位点的多态性差异较大,不同MIRU位点组合(12、15和24位点)的分辨率指数依次升高,后两个组合的差异是由位点ETR-B引起.各位点和各位点组合在北京家族菌株中的分辨率指数均高于非北京家族菌株.结论 重庆地区儿童MTB具有明显的基因多态性,其主要流行型为北京家族.在结核病原学监测中,可先采用Spoligotyping,再对成簇菌株进行15位点与ETR-B组合二次分型的联合分型策略,可提高分子流行病学调查效果.

Abstract：

Objective To evaluate the application of spacer oligonucleotide typing (Spoligotyping) and mycobaeterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) analysis in the molecular-epidemiological study of tuberculosis and to discuss the characteristics of pediatric Mycobacterium (M.) tuberculosis strains in Chongqing. Methods M. tuberculosis strains isolated and typed by Spoligotyping and MIRU-VNTR respectively, from the children patients in Chongqing and to compare the results from both methods, epidemiologically. Results By means of Spoligotyping, 210 clinical isolates were divided into 2 gene groups, displaying 44 genotypes. Among them, the biggest group was M. tuberculosis Beijing family, including 130 strains (61.90%) ,using the Spoligotyping. From the results of MIRU-VNTR, 24 loci showed different polymorphism and the HGI of different loci set (12 old loci, 15 basic loci and 24-loci set) increased accordingly. The subtle difference in HGI was originated from one locus ETR-B, which was included in the 24-locus system. The diversity of each loci and MIRU-VNTR set for non-Beijing genotype strains was higher than that of the Beijing genotype strains. Conclusion In this study, it was preliminarily confirmed the existence of high polymorphism of M. tuberculosis while the Beijing Family was the main genotype and main prevalent strain in children of Chongqing area. Spoligotyping prior to 15-locus with ETR-B combination seemed more suitable for the massive epidemiological investigation of pediatric tuberculosis patients.     

Molecular detection methods of resistance to antituberculosis drugs in Mycobacterium tuberculosis

Objective

Molecular methods predict drug resistance several weeks before phenotypic methods and enable rapid implementation of appropriate therapeutic treatment. We aimed to detail the most representative molecular tools used in routine practice for the rapid detection of resistance to antituberculosis drugs among Mycobacterium tuberculosis strains.

Molecular identification of streptomycin monoresistant Mycobacterium tuberculosis related to multidrug-resistant W strain.

A distinct branch of the Mycobacterium tuberculosis W phylogenetic lineage (W14 group) has been identified and characterized by various genotyping techniques. The W14 group comprises three strain variants: W14, W23, and W26, which accounted for 26 clinical isolates from the New York City metropolitan area. The W14 group shares a unique IS6110 hybridizing banding motif as well as distinct polymorphic GC-rich repetitive sequence and variable number tandem repeat patterns. All W14 group members have high levels of streptomycin resistance. When the streptomycin resistance rpsL target gene was sequenced, all members of this strain family had an identical mutation in codon 43. Patients infected with the W14 group were primarily of non- Hispanic black origin (77%); all were US-born. Including HIV positivity, 84% of the patients had at least one known risk factor for tuberculosis.     

Molecular epidemiology of bovine tuberculosis. I. Mycobacterium bovis genotyping

The lack of a typing system for Mycobacterium bovis has, until recently, been an impediment to undertaking sophisticated epidemiological studies to assist in the control and eradication of tuberculosis in domestic animals. Molecular biology techniques for mycobacteria have been in development since the mid-1980s, leading to the availability of a number of genetic typing systems for M. bovis. The authors summarise the available techniques, identify those which are most useful at present and those which might prove useful in the future. The present recommendation is to use spoligotyping analysis for rapid, large scale screening of M. bovis isolates, and to use restriction fragment length polymorphism analysis using the polymorphic guanine and cytosine-rich repeat sequences probe where greater differentiation of isolates is required. In the future, systematic analysis of the genome sequence of M. bovis will allow the development of improved techniques that combine good discrimination with ease of use.     

Potential of Mycobacterium vanbaalenii as a model organism to study drug transporters of Mycobacterium tuberculosis, Mycobacterium marinum and Mycobacterium ulcerans: homology analysis of M. tuberculosis drug transporters among mycobacterial species

Drug efflux pumps have been one of the important mechanisms of drug resistance in Mycobacterium tuberculosis. There is a prerequisite to study the behavior and mechanisms of these drug efflux pumps in detail for being considered in future anti-TB drug designing. The need of a rapid grower non-pathogenic mycobacterium with significant genomic homology for such type of studies is often being felt. During microarray and Real-Time PCR analysis of drug efflux pump genes of M. tuberculosis, we found 10 genes to be over-expressed during stress induced by common anti-TB drugs. In the present study homology analysis of these genes was done in order to know its phylogenetic relationship among other bacteria/mycobacteria. It was found that amino acid sequences of 7 out of 10 genes were significantly (>40%) identical to a non-pathogenic rapid grower environmental mycobacterium, Mycobacterium vanbaalenii. The protein sequences of M. vanbaalenii share important sequence motifs with M. tuberculosis useful for drug efflux mechanism based study across species. Like Mycobacterium smegmatis, it can be used as a model organism to study drug efflux pumps of M. tuberculosis and also other pathogenic mycobacteria such as Mycobacterium ulcerans and Mycobacterium marinum.     

Molecular mechanisms of multidrug resistance in Mycobacterium tuberculosis

Control of tuberculosis caused by multidrug-resistant (MDR) Mycobacterium (M.) tuberculosis has become one of the major problems throughout the world. Understanding of the molecular mechanisms of resistance may help in the development of novel methods for the rapid and precise detection of drug-resistant M. tuberculosis. Eight agents have been recommended to treat tuberculosis. Isoniazid (INH), rifampicin (RFP), pyrazinamide (PZA), streptomycin(SM), and ethambutol (EB) are used as the first line agents, and the others are the second line agents. MDR M. tuberculosis strains are resistant both to INH and RFP which have the most effective bactericidal activity to M. tuberculosis. Nearly 95% of RFP resistant strains possess a mutation on the rpoB gene encoding a DNA-dependent RNA polymerase. INH particularly shows an inhibition of the cell wall synthesis of M. tuberculosis and approximately 90% of INH resistant strains have a mutation on the inhA, katG, and ahpG gene encoding enzymes related to a mycolic acid synthesis of cell wall. PZA resistant strains have a mutation on the pncA gene encoding a pyrazinamidase which degradates pyrazinamide to a bactericidal substance, pyrazinoic acid. SM resistant strains have a mutation on the rrs and rpsL gene encoding a 16S rRNA and a S12 ribosomal subunit protein, respectively. EB resistant strains have a mutation on the embB gene encoding a arabinosyl transferase which catalyzes cell wall synthesis. Resistant mechanisms of second-line agents have also been identified. Recently, rapid detection methods for RFP and INH resistant mutations have been developed on the basis of these studies.     

Aspects of tuberculosis in Africa. 3. Genetic 'fingerprinting' for clues to the pathogenesis of tuberculosis.

The recent discovery of a repetitive element within the DNA of Mycobacterium tuberculosis, which is present in variable numbers at different locations in separate strains of the organism, has led to the development of genetic 'fingerprinting' to distinguish between different isolates. Clusters of cases of tuberculosis have been identified in Europe and the USA in which the organisms cultured had identical 'fingerprints' confirming that transmission was occurring. Unrelated isolates generally have distinct 'fingerprints'. In Africa, where transmission is more common than in Europe, there is less heterogeneity between isolates. We have typed 117 isolates of M. tuberculosis collected from continuing studies in Malawi and Kenya. Paired isolates from an individual patient produced matching 'fingerprints' in 22 of 25 cases. There were 18 isolates which had an identical matched pair from a separate patient; we have not yet found any epidemiological link between these patients. These data show that there is sufficient heterogeneity amongst African isolates of M. tuberculosis to make studies of transmission feasible and to address questions of pathogenesis and epidemiology.     

Host immunity to Mycobacterium tuberculosis and risk of tuberculosis: A longitudinal study among Greenlanders

BackgroundHuman immune responses to latent Mycobacterium tuberculosis (Mtb) infection (LTBI) may enable individuals to control Mtb infection and halt progression to tuberculosis (TB), a hypothesis applied in several novel TB vaccines. We aimed to evaluate whether immune responses to selected LTBI antigens were associated with subsequent reduced risk of progression to TB.MethodsWe conducted a population-based cohort study in East Greenland (2012–2014) including individuals aged 5–31 years. A personal identifier allowed follow-up in national registers including the TB notification register. Mtb infection was defined by a positive Quantiferon test. Immune responses to LTBI antigens were assessed by whole blood antigen stimulation and interferon gamma measurement.ResultsAmong 978 participants, 67 previously had TB. LTBI antigen (Rv1284, Rv2659, Rv2660c) immune response prevalence was 18%, 50%, 2% among Mtb-infected and 7%, 40%, 4% among non-infected (Quantiferon negative) participants. Among 911 participants without prior notified TB, 31 were notified with TB during study follow-up. Immune responses to LTBI antigens were not associated with reduced risk of subsequent TB; Rv1284 HR 0.92 (95%CI 0.28–3.04), Rv2659 HR 1.05 (95%CI 0.51–2.13), Rv2660c HR 3.06 (95%CI 0.70–13.37).ConclusionIn this large population-based study, human immune responses to selected LTBI antigens were not found to be strongly associated with reduced risk of subsequent TB.     

Increase in Mycobacterium avium complex isolations among patients admitted to a general hospital.

In early 1979, an official of an Illinois hospital reported an increase in the number of patients from whom Mycobacterium avium complex recently had been recovered. Over the preceding 3 years specimens from a total of 51 patients were culture positive for M. avium complex: 7 in 1976, 8 in 1977, and 36 in 1978. Nine of 10 serotyped isolated were serotype 8. The increase was not attributable to an increase in the number of mycobacterial cultures performed. No other area hospitals had similar increases in rates of recovery of M. avium complex. Patients with M. avium complex were significantly more likely than patients with other mycobacteria to have been residents of the city where the hospital is located. The distribution of abnormalities in patients'' chest films differed significantly between patients with M. avium complex in 1978 and patients with M. avium complex in 1976-77; in 1978, patients although equally likely to have infiltrates, nodules, or cavities, were more likely to have no abnormalities or abnormalities consistent with chronic obstructive pulmonary disease, and less likely to have other abnormalities. The data suggest that the increased rate of recovery of M. avium complex from patients could not be attributed to ascertainment bias or laboratory variation but may be due to an increase in the incidence of disease or colonization among persons living in the community where the hospital is located.     

煤矿工尘肺结核患者结核分枝杆菌L型耐药基因rpoB序列分析

目的 探讨淮南矿区尘肺结核患者感染结核分枝杆菌L型利福平耐药基因rpoB突变特点.方法 收集结核分枝杆菌L型临床分离株42株,其中利福平耐药株31株,敏感株11株,抽提临床分离株DNA和H37Rv标准菌株DNA,PCR法扩增rpoB基因,并应用全自动DNA测序仪对rpoB基因的突变集中区域进行测序分析.结果 42株结核分枝杆菌L型中,31株耐药株rpoB基因突变率93.55%(29/31),主要集中在531位点(51.61%,16/31)和526位点(32.26%,10/31)碱基置换突变,新发现516位点突变目前在国内外研究中未见报道.11株敏感株未见rpoB基因单链构象异常.结论 高度保守的rpoB基因突变是导致结核分枝杆菌L型利福平耐药的分子基础,其突变位点呈多样性.