Clinical Strains Of Mycobacterium Tuberculosis Research Articles

Kinetics of recA and recX induction in drug-susceptible and MDR clinical strains of Mycobacterium tuberculosis.

To investigate and compare the expression of recA and recX, components of the SOS pathway, following rifampicin treatment in drug-susceptible and MDR clinical strains of Mycobacterium tuberculosis. Strains (M. tuberculosis and Mycobacterium smegmatis) were subjected to rifampicin- and mitomycin-induced stress for 36 h followed by RNA extraction. recA and recX in the RNA extract were estimated using qRT-PCR. The MDR clinical strain induced faster (24 h) and higher (7-fold) levels of recA as compared with the drug-susceptible strain (36 h) in response to rifampicin. recX levels were found to rise with an increase in levels of recA; however, the levels were relatively higher than recA. Drug-susceptible and MDR strains have different kinetics of induction of DNA repair.

Comparison of ambient air survival of Mycobacterium tuberculosis clinical strains associated with different epidemiological phenotypes

This study compared the ambient air survival of two clinical strains of Mycobacterium tuberculosis that had caused significantly different numbers of cases in the same population. No difference in the survival ability between the two strains was found. However, a significant difference was observed in colony morphology between the two strains. These findings provide new insight into potential microbial determinants for the occurrence of large clusters of tuberculosis cases in a population.

Characterization of pncA and rpsA mutations in pyrazinamide-resistant M. tuberculosis

Objective To investigate the characterizations and contributions of mutations in pncA and rpsA whole genes sequence in pyrazinamide(PZA) resistant Mycobacterium tuberculosis(MTB). Methods All of the 161 clinical strains of MTB collected from Guangzhou Chest Hospital during September 2010 and November 2012 were subjected to determine the susceptibilities to PZA by the MGIT 960 PZA system and to obtain pncA and rpsA whole gene sequences by DNA sequencing.Then the significant difference of pncA and rpsA mutation between the PZA resistant and susceptible isolates were analyzed by chi square test. Results The mutation frequency of 52 PZA resistant isolates was 84.6%(44/52), but the 109 PZA susceptible isolates had no mutations, which showed highly significant difference of pncA mutation frequency between the PZA resistant and the susceptible isolates (χ2=126.92, P=0.00).rpsA mutation was observed in 3 PZA resistant MTB isolates while only 1 PZA susceptible ones was found rpsA mutation, which exhibited no significant difference of rpsA mutation between the PZA resistant and the susceptible isolates (χ2=3.42, P=0.06).Thirty four types of pncA mutations were found in 44 PZA resistant isolates of MTB, including 12 novel mutations (L deletion at 27, E deletion at 91, E deletion at 111, Q deletion at 122, VVG deletions at 130 to 132, V deletion at 131, D8A, S18P, H57Y, F58S, E174G and M175R substitutions) and 1 promoter mutation at -11 nucleotide position with A to G.The identified mutations were randomly dispersed on the pncA whole gene sequence, but 9 isolates were observed with pncA mutations centralized in the region of G132-T142. Three PZA-resistant isolates，without pncA mutation, were observed with rpsA mutations of R474W, R474L, and E433D at C-terminus, and 1 PZA-susceptible strain showed mutation of Q162R in rpsA. Conclusions In the study, mutations in pncA gene is the major mechanism of PZA resistance and direct sequencing the pncA gene by PCR should help to rapidly identify PZA-resistant clinical strains of MTB.Furthermore, novel mutations of pncA in the study indicate the regional investigations are necessary for learning about the characteristics of pncA mutations in PZA-resistant strains of MTB.However, 3′ terminal of rpsA gene sequence may be added as the second PZA resistant relevant region for molecular identification of PZA susceptibility.（Chin J Lab Med,2014,37:285-289） Key words: Mycobacterium tuberculosis; Pyrazinamide; Mutation

Correlation between Genotypic and Phenotypic Testing for Resistance to Rifampin in Mycobacterium tuberculosis Clinical Isolates in Haiti: Investigation of Cases with Discrepant Susceptibility Results

The World Health Organization has recommended use of molecular-based tests MTBDRplus and GeneXpert MTB/RIF to diagnose multidrug-resistant tuberculosis in developing and high-burden countries. Both tests are based on detection of mutations in the Rifampin (RIF) Resistance-Determining Region of DNA-dependent RNA Polymerase gene (rpoB). Such mutations are found in 95–98% of Mycobacterium tuberculosis strains determined to be RIF-resistant by the “gold standard” culture-based drug susceptibility testing (DST).We report the phenotypic and genotypic characterization of 153 consecutive clinical Mycobacterium tuberculosis strains diagnosed as RIF-resistant by molecular tests in our laboratory in Port-au-Prince, Haiti. 133 isolates (86.9%) were resistant to both RIF and Isoniazid and 4 isolates (2.6%) were RIF mono-resistant in MGIT SIRE liquid culture-based DST. However the remaining 16 isolates (10.5%) tested RIF-sensitive by the assay.Five strains with discordant genotypic and phenotypic susceptibility results had RIF minimal inhibitory concentration (MIC) close to the cut-off value of 1 µg/ml used in phenotypic susceptibility assays and were confirmed as resistant by DST on solid media. Nine strains had sub-critical RIF MICs ranging from 0.063 to 0.5 µg/ml. Finally two strains were pan-susceptible and harbored a silent rpoB mutation.Our data indicate that not only detection of the presence but also identification of the nature of rpoB mutation is needed to accurately diagnose resistance to RIF in Mycobacterium tuberculosis. Observed clinical significance of low-level resistance to RIF supports the re-evaluation of the present critical concentration of the drug used in culture-based DST assays.

Understanding Rifampicin Resistance in Tuberculosis through a Computational Approach.

The disease tuberculosis, caused by Mycobacterium tuberculosis (MTB), remains a major cause of morbidity and mortality in developing countries. The evolution of drug-resistant tuberculosis causes a foremost threat to global health. Most drug-resistant MTB clinical strains are showing resistance to isoniazid and rifampicin (RIF), the frontline anti-tuberculosis drugs. Mutation in rpoB, the beta subunit of DNA-directed RNA polymerase of MTB, is reported to be a major cause of RIF resistance. Amongst mutations in the well-defined 81-base-pair central region of the rpoB gene, mutation at codon 450 (S450L) and 445 (H445Y) is mainly associated with RIF resistance. In this study, we modeled two resistant mutants of rpoB (S450L and H445Y) using Modeller9v10 and performed a docking analysis with RIF using AutoDock4.2 and compared the docking results of these mutants with the wild-type rpoB. The docking results revealed that RIF more effectively inhibited the wild-type rpoB with low binding energy than rpoB mutants. The rpoB mutants interacted with RIF with positive binding energy, revealing the incapableness of RIF inhibition and thus showing resistance. Subsequently, this was verified by molecular dynamics simulations. This in silico evidence may help us understand RIF resistance in rpoB mutant strains.

Pathways of IL-1β secretion by macrophages infected with clinical Mycobacterium tuberculosis strains

SummaryThe pro-inflammatory cytokine IL-1β is a key mediator of inflammation and plays an important role in the host resistance to Mycobacterium tuberculosis infections. To date, most studies have examined the mechanisms of IL-1β secretion using laboratory strains of M. tuberculosis and the findings may not be widely applicable to contemporary clinical strains. Here, we investigated the primary pathways of IL-1β secretion in macrophages infected with a panel of 17 clinical M. tuberculosis isolates, representing Euro-American, Indo-Oceanic and East-Asian/Beijing lineages. Our aim was to dissect the pathways involved in M. tuberculosis induced IL-1β secretion and to determine whether they are common to all clinical isolates. We found that the isolates were capable of eliciting variable concentrations of IL-1β from infected murine macrophages, but this phenomenon could not be attributed to differential IL-1β mRNA transcription or pro-IL-1β accumulation. We demonstrate that viable bacteria are required to induce IL-1β secretion from macrophages, but IL-1β secretion was only partially abrogated by caspase-1 inhibition. Almost complete IL-1β secretion inhibition was produced with combined caspase-1 and some serine protease inhibitors. Taken together, these findings demonstrate that clinical strains of M. tuberculosis employ a unique caspase-1 independent pathway to stimulate IL-1β secretion from macrophages.

Discovery of Novel Acetohydroxyacid Synthase Inhibitors as Active Agents againstMycobacterium tuberculosisby Virtual Screening and Bioassay

Acetohydroxyacid synthase (AHAS) has been regarded as a promising drug target against Mycobacterium tuberculosis (MTB) as it catalyzes the biosynthesis of branched-chain amino acids. In this study, 23 novel AHAS inhibitors were identified through molecular docking followed by similarity search. The determined IC(50) values range from 0.385 ± 0.026 μM to >200 μM against bacterium AHAS. Five of the identified compounds show significant in vitro activity against H37Rv strains (MICs in the range of 2.5-80 mg/L) and clinical MTB strains, including MDR and XDR isolates. More impressively, compounds 5 and 7 can enhance the killing ability against macrophages infected pathogen remarkably. This study suggests our discovered inhibitors can be further developed as novel anti-MTB therapeutics targeting AHAS.

Anthelmintic Avermectins Kill Mycobacterium tuberculosis, Including Multidrug-Resistant Clinical Strains

Avermectins are a family of macrolides known for their anthelmintic activities and traditionally believed to be inactive against all bacteria. Here we report that members of the family, ivermectin, selamectin, and moxidectin, are bactericidal against mycobacterial species, including multidrug-resistant and extensively drug-resistant clinical strains of Mycobacterium tuberculosis. Avermectins are approved for clinical and veterinary uses and have documented pharmacokinetic and safety profiles. We suggest that avermectins could be repurposed for tuberculosis treatment.

Genotypes and drug susceptibility of Mycobacterium tuberculosis Isolates in Shihezi, Xinjiang Province, China

BackgroundTuberculosis (TB) remains a major global health problem. To investigate the genotypes of Mycobacterium tuberculosis (MTB) and the distribution of Beijing family strains, molecular epidemiology technologies have been used widely.MethodsFrom June 2010 to June 2011, 55 M. tuberculosis isolates from patients with pulmonary TB were studied by Beijing family-specific PCR (detection of the deletion of region of difference 105 [RD105]), and mycobacterial interspersed repetitive units variable number tandem repeat (MIRU-VNTR) analysis. Twenty-four MIRU-VNTR loci defined the genotypes and clustering characteristics of the local strains. All strains were subjected to a drug susceptibility test (DST) by the proportion method on Lowenstein-Jensen (LJ) culture media.ResultsFifty-five clinical isolates of MTB were collected. Beijing family strains represented 85.5% of the isolates studied. Using 24 loci MIRU-VNTR typing categorized the strains into eight gene groups, 46 genotypes, and seven clusters. 83.6% (46/55) of the isolates belonged to the largest gene group. Thirty-six isolates (65.5%) were susceptible, nineteen (34.5%) were resistant to at least one drug, seven (12.8%) were Multidrug-Resistant Tuberculosis (MDR TB), and two (3.6%) were extremely drug-resistant tuberculosis (XDR-TB).ConclusionThe results showed there were obvious polymorphisms of VNTRs of MTB clinical strains. Beijing family strains of MTB were predominant in the Shihezi region of Xinjiang province. There was no correlation between the drug-resistance and Beijing family strains of MTB. It is necessary to strengthen the monitoring, treatment, and management of drug-resistance TB in Shihezi region, Xinjiang.

Cross-resistance between rifampin and rifabutin in multidrug resistant Mycobacterium tuberculosis complex strains

To study the cross-resistance between rifampin and rifabutin in multidrug resistant Mycobacterium tuberculosis complex strains, and therefore to provide laboratory data for using rifabutin in the treatment of multidrug resistant tuberculosis. The MIC(90) of rifabutin and rifampin against 99 multidrug resistant Mycobacterium tuberculosis clinical strains were determined by microplate assays. Statistical analysis was performed by using the χ(2) test and the t test. The cross-resistance rate between rifampicin and rifabutin was 85.9% (85/99), but the MIC(90) of rifabutin (≤ 16 mg/L, median 2 mg/L) was significantly lower than that of rifampicin (≥ 2 mg/L, median > 32 mg/L). The cross-resistance rate increased with the resistance level of rifampicin. The cross-resistance strains in the lower and the medium groups were 0/9 and 5/9 respectively, while the strains of the high rifampicin-resistant group were almost all cross-resistant (98.8%, 80/81). Rifabutin had activities against rifampin resistant Mycobacterium tuberculosis complex strains in vitro, and therefore may be used as an alternative for the treatment of multidrug resistant tuberculosis.

Characterization of gyrA and gyrB mutations and fluoroquinolone resistance in Mycobacterium tuberculosis clinical isolates from Hubei Province, China

ObjectiveThe study aimed to investigate gyrA and gyrB mutations in Mycobacterium tuberculosis (MTB) clinical strains from 93 patients with pulmonary tuberculosis in Hubei Province, China, and analyze the association between mutation patterns of the genes and ofloxacin resistance level. ResultsAmong 93 MTB clinical isolates, 61 were ofloxacin-resistant by the proportion method, and 32 were ofloxacin-susceptible MDR-TB. No mutation in the gyrB gene was found in any MTB strains. In the 61 ofloxacin-resistant isolates, 54 mutations were observed in the gyrA gene. Only one mutation in the gyrA gene was found in ofloxacinsusceptible MDR-TB isolates. In this study, the mutation patterns of gyrA involved seven patterns of single codon mutation (A90V, S91P, S91T, D94N, D94Y, D94G or D94A) and two patterns of double codons mutation (S91P & D94H, S91P & D94A). The ofloxacin minimal inhibitory concentrations (MICs) of three patterns of single codon mutations in the gyrA gene (codons 94, 90 and 91) showed a statistically significant difference (p<0.0001). ConclusionsThe gyrA mutations at codons 90, 91 and 94 constitute the primary mechanism of fluoroquinolone resistance in MTB, and mutations at codon 91 in the gyrA gene may be associated with low-level resistance to ofloxacin.

Detection of isoniazid and rifampin resistance of Mycobacteriumtuberculosis by a multiplex allele-specific polymerase chain reaction (PCR) assay

Background: The use of molecular techniques is a major improvement for the rapid routine detection and control of multidrug-resistant tuberculosis (MDR-TB).Materials: In this study, the multiplex allele-specific polymerase chain reaction (MAS-PCR) was developed to simultaneously detect the most frequent mutations associated with isoniazid (INH) and rifampin (RIF) resistance in a single assay.Results: The assay was tested with 53 clinical isolates. Among them, 27 were MDR strains, 17 were mono-resistant to INH, one was mono-resistant to RIF, and eight were susceptible. The MAS-PCR assay showed a specificity of 100% in detecting drug resistance. An equivalent sensitivity of 92.6% in detecting MDR and RIF-resistance was found. The sensitivity for the detection of INH-resistance was 88.6%.Conclusions: The MAS-PCR assay was a simple and rapid method for detecting the INH and RIF-resistance in Mycobacterium tuberculosis (MT) clinical strains. It is also easy to perform and to interpret. The assay is inexpensive and a less-demanding technique.

Low Dose Aerosol Fitness at the Innate Phase of Murine Infection Better Predicts Virulence amongst Clinical Strains of Mycobacterium tuberculosis

BackgroundEvaluation of a quick and easy model to determine the intrinsic ability of clinical strains to generate active TB has been set by assuming that this is linked to the fitness of Mycobacterium tuberculosis strain at the innate phase of the infection. Thus, the higher the bacillary load, the greater the possibility of inducting liquefaction, and thus active TB, once the adaptive response is set.Methodology/Principal FindingsThe virulence of seven clinical Mycobacterium tuberculosis strains isolated in Spain was tested by determining the bacillary concentration in the spleen and lung of mice at weeks 0, 1 and 2 after intravenous (IV) inoculation of 104 CFU, and by determining the growth in vitro until the stationary phase had been reached. Cord distribution automated analysis showed two clear patterns related to the high and low fitness in the lung after IV infection. This pattern was not seen in the in vitro fitness tests, which clearly favored the reference strain (H37Rv). Subsequent determination using a more physiological low-dose aerosol (AER) inoculation with 102 CFU showed a third pattern in which the three best values coincided with the highest dissemination capacity according to epidemiological data.Conclusions/SignificanceThe fitness obtained after low dose aerosol administration in the presence of the innate immune response is the most predictive factor for determining the virulence of clinical strains. This gives support to a mechanism of the induction of active TB derived from the dynamic hypothesis of latent tuberculosis infection.

Pyrosequencing for rapid detection of resistance to rifampin, isoniazid, ofloxacin and amikacin in Mycobacterium tuberculosis

Objective To develop an assay to determine Mycobacterium tuberculosis resistance to rifampin, isoniazid, ofloxacin and amikacin by pyrosequencing and evaluate the value of this method in clinical application. Methods Eighty-nine clinical isolates of Mycobacterium tuberculosis from tuberculosis patients were collected from Shanghai Pulmonary Hospital during 2008 to 2009. All strains were isolated from decontaminated sputum, cultured on Lowenstein-Jensen media and identified by traditional biochemical tests with standard methods. Ten Mycobacterium tuberculosis were selected from the strain bank of Shanghai Pulmonary Hospital. The optimal conditions of detection of rpoB, katG, gyrA and rrs gene by pyroseuencing were determined, using the 10 Mycobacterium tuberculosis strains whose drug susceptibility of Bactec 960 and sequence of rpoB, katG, gyrA, rrs gene were known. Then the drug susceptibility of 89 Mycobacterium tuberculosis clinical isolate strains were detected by pyrosequencing using this conditions and the results were compared with that of the Bactec 960 methods. Results The pyrosequencing program of sequence analysis was suitable for the detection of the mutations of rpoB and gyrA genes, and the program of single nucleotide polymorphism was suitable for katG and rrs genes. Among the 89 Mycobacterium tuberculosis clinical isolates,when using the drug susceptibility of Bactec 960 as the standard, the sensitivity of rifampin, isoniazid,ofloxacin and amikacin is 98.0%, 64. 1%, 79.5%, 78. 3% respectively, the specificity is 97.5%,100. 0%, 90. 0%, 100. 0% respectively, the accuracy is 97.8%, 77. 5%, 85.4%, 94. 4% respectively,tested by pyrosequencing. The results of the detection of resistance to rifampin, isoniazid, ofloxacin and amikacin in Mycobacterium tuberculosis using pyrosequencing technique were almost the same with that of Bactec 960, and Kappa ≥0. 7 in each detection. Conclusion Pyrosequencing is thus a rapid, accurate and high throughput method for detecting Mycobacterium tuberculosis resistance to these four drugs. Key words: Mycobacterium tuberculosis; Antitubercular agents; Sequence analysis, DNA; Microbial sensitivity tests

Usefulness of resistant gene markers for predicting treatment outcome on second-line anti-tuberculosis drugs

Mutations in rrs [nucleotide (nt) 1401], gyrA gene (codons 90, 91 or 94), tlyA, ethA and thyA genes of Mycobacterium tuberculosis (MTB) were evaluated for their usefulness in predicting treatment outcome of kanamycin (KM), capreomycin (CPM), ofloxacin (OFX), ethionamide (ETH) and para-aminosalicylic acid (PAS). DNA sequence analyses of these genes were performed against 188 MTB isolates obtained from patients put on second-line anti-TB drugs (SLDs) with well-documented clinical history and treatment outcome. Mutations in rrs and gyrA have 100% positive predictive value (PPV) in predicting treatment failure for KM and OFX, while 88·9 and 80% were obtained, respectively, when tlyA and rrs mutations were considered in CPM. For ETH and PAS, the PPV of using ethA and thyA mutations to predict treatment failure was 82·5 and 89·3%, respectively. Our study demonstrated high specificities of gene mutations in predicting poor treatment outcome; however, further technical advancement is required to make the molecular detection of resistances to other SLDs feasible in clinical laboratories. This is the first study to correlate different polymorphisms of major SLD resistance gene markers with predicted treatment outcome, using an international set of well-documented clinical MTB strains.

Genotyping analysis of 151 clinical isolates of Mycobacterium tuberculosis from Uygur in south of Xinjiang

Objective To investigate the application of the multiple locus variable numbers of tandem repeats(MLVA) in genotype Mycobacterium tuberculosis(MTB) strains isolated from Uygur in south of Xinjiang, and to understand the characteristics of genotype and distribution. Methods One hundred and fifty-one Mycobacterium tuberculosis strains were collected from Uygur in south of Xinjiang which contains three regions, Kashgar, Hotan and Kizilsu kirghiz. Twenty-four tandem repeats loci in the total genome of MTB were analyzed by PCR and agarose gel electrophoresis method. The characteristics on polymorphism of DNA fingerprinting of 151 MTB strains were analyzed with BioNumerics 5.0 software. Results Twenty-four MLVA loci of 151 MTB strains were analyzed respectively. The results showed that there were obvious polymorphisms of VNTRs. The clustering of genotype showed that these strains could be categorized into 8 gene groups( Ⅰ , Ⅱ , Ⅲ ,Ⅳ, Ⅴ ,Ⅵ,Ⅶ ,Ⅷ) and 151 genotypes. Sixty-seven isolates(44.4% ) belonged to group Ⅵ. 23.2% were group Ⅷ including 35 genotypes, 20. 5% were group Ⅳ including 31 genotypes. The group Ⅵ prevailed mostly in the Kashgar. The group Ⅲ prevailed mostly in the HOTAN. Conclusion The results showed there were obvious polymorphisms of VNTRs of Mycobacterium tuberculosis clinical strains preliminarily. Group Ⅵ was the predominant prevalent strain in south of Xinjiang. Key words: Mycobacterium tuberculosis; Uygur; Multiple locus variable numbers of tandem repeats; Genotyping

Specific bacterial genotypes of Mycobacterium tuberculosis cause extensive dissemination and brain infection in an experimental model

Meningeal tuberculosis is a severe type of extrapulmonary disease, which is thought to begin with respiratory infection, followed by hematogenous dissemination and brain infection. Host genetic susceptibility factors and specific mycobacterial substrains could be involved in its development. From an epidemiological study in Colombia, we selected three Mycobacterium tuberculosis clinical strains isolated from the cerebrospinal fluid (CSF) of patients with meningeal tuberculosis, and used them to infect BALB/c mice through the intratracheal route. These strains showed a distinctive spoligotype pattern. The course of infection in terms of strain virulence (mice survival, bacillary loads in lungs), bacilli dissemination and extrapulmonary infection (bacilli loads in blood, brain, liver, kidney and spleen), and immune responses (cytokine expression determined by real time PCR in brain and lung) was studied and compared with that induced by the laboratory strain H37Rv and other five clinical strains isolated from patients with pulmonary TB. All the clinical isolates from meningeal TB patients disseminated extensively through the hematogenous route infecting the brain, producing inflammation in the cerebral parenchyma and meninges, whereas H37Rv and clinical isolates from pulmonary TB patients showed very limited efficiency to infect the brain. Thus, it seems that mycobacterial strains with a distinctive genotype are able to disseminate extensively after the respiratory infection and infect the brain.

Methodological research of MIC microtiter susceptibility testing for Mycobacterium tuberculosis

Objective To establish of MIC in microtiter as drug susceptibility testing for Mycobacterium tuberculosis(microwell-MIC-test)and evaluate clinical application of this method in Mycobacterium tuberculosis.Methods 60 Mycobacterium tuberculosis clinical isolates which were stored in Shanghai Pulmonary Hospital and whose drug susceptibility status of Bactec MGIT was known were as control.MICs of these 60 Mycobacterium tuberculosis strains were detected in liquid culture in 96-well plate.According to the results of Bactec MGIT.the best cut-off value were chosen by ROC analysis.The drug susceptibility of 80 Mycobacterium tuberculosis clinical isolate strains which were collected continuously from tuberculosis patients in our hospital were detected by Microwell-MIC-test.Bactec MGIT method was used at the sanle time to evaluate and amend the cut-off valne.Results The best concentration of Mycobacterium tuberculosis in microwell is 10~(-3) mg/ml.The best results were read after 7-10 d The best cut-off value of drug susceptibility testing of isoniazid,streptomycin,rifampicin,ethambutol,ofloxacin,amikacin,capreomycin were 2μg/ml,0.25μg/ml,1 μg/ml,2μg/ml,1 μg/ml,4μg/ml and 4μg/ml,respectively,and the seusitivities were 93.5%,97.7%,93.5%,84.4%,95.8%,91.7% and 88.9% respectively,the specificities were 95.6%, 94.6%,100.0%,93.8%,92.9%,95.6% and 91.5% respectively.The accuracies were 95.0%,96.3%,97.5%,90.0%,93.8%,95.0% and 91.3%respectively.Conlusion The drug susceptibility testing method of microwell-MIC-test is accurate,rapid,low-cost and simple and worthy in application in tuberculosis hospital of resource limited countries like China. Key words: Mycobacterium tuberculosis; Microbial sensitivity tests

Study on molecular characteristics regarding DNA genotype of Mycobacterium tuberculosis clinical strains in Shandong

To establish the molecular characteristics of Mycobacterium tuberculosis and on factors influencing the recent transmission of drug resistant isolates in Shandong. Mycobacterium tuberculosis isolated from active pulmonary tuberculosis patients of 13 counties were genotyped by mycobacterial interspersed repetitive units (MIRU) methods. 12 loci of MIRU were detected in 558 isolates and a total of 143 MIRU patterns were confirmed. 66 isolates had distinct patterns, and 481 (86.2%) strains were in clusters. Shandong cluster included 177 strains with 74.6% of the isolates belonged to Beijing family. The recent transmission index of multi-drug resistance strains was in lower level, comparing to the susceptible strains. Our results showed that the Shandong cluster isolates had capacities of facilitating person-to-person transmission and high level of drug resistance.

HIV-1 Replication Is Differentially Regulated by Distinct Clinical Strains of Mycobacterium tuberculosis

BackgroundTuberculosis (TB) is the largest cause of death in human immunodeficiency virus type 1 (HIV-1) infection, having claimed an estimated one third to one half of the 30 million AIDS deaths that have occurred worldwide. Different strains of Mycobacterium tuberculosis (MTb), the causative agent of TB, are known to modify the host immune response in a strain-specific manner. However, a MTb strain-specific impact upon the regulation of HIV-1 replication has not previously been established.Methology/Principal FindingsWe isolated normal human peripheral blood mononuclear cells (PBMC) and co-infected them with HIV-1 and with either the well characterized CDC1551 or HN878 MTb clinical isolate. We show that HIV-1 co-infection with the CDC1551 MTb strain results in higher levels of virus replication relative to co-infection with the HN878 MTb strain ex vivo. Furthermore, we show that the distinct pattern of CDC1551 or HN878 induced HIV-1 replication is associated with significantly increased levels of TNF and IL-6, and of the transcription and nuclear translocation of the p65 subunit of the transcription factor NF-κB, by CDC1551 relative to HN878.Conclusions/SignificanceThese results provide a precedent for TB strain-specific effects upon HIV-1 replication and thus for TB strain-specific pathogenesis in the outcome of HIV-1/TB co-infection. MTb strain-specific factors and mechanisms involved in the regulation of HIV-1 during co-infection will be of importance in understanding the basic pathogenesis of HIV-1/TB co-infection.