Beijing Strains Research Articles

Pediatric tuberculosis: clinical and epidemiological reflections from a highly endemic setting

Pediatric TB provides unique opportunities to study TB disease epidemiology. Improved diagnostics are of key importance in order to address many of the challenges posed by TB in children. In the Western Cape Province in South Africa, the TB notification rate was more than 600 out of 100,000 for children aged 0-14 years in 2007; the maternal HIV prevalence was 15%, with a good vertical preventative program. The HIV transmission rate was 4-5%; 99% of neonates routinely receive BCG vaccination at birth. Isoniazid prophylaxis, shown to be effective in the prevention of TB in young children, is seldom initiated and many missed opportunities for preventive therapy exist. In children admitted to hospital, mycobacterial culture is routinely done for TB in children less than five years of age through gastric aspiration of stomach contents in this setting; the culture yield is 30-40% in children with clinically suspected TB. In a recent study of infants admitted to the three Cape Town hospitals over a three-year period, 55% of children born to HIV positive mothers had a household contact with TB, indicating a high level of TB exposure. A high risk of serious BCG vaccine complications exists in HIV-positive infants in the form of disseminated BCG disease, with an incidence of 992 per 100 000 (95% CI: 567-1495). More research is needed to determine if BCG vaccination protects against TB in infants born to HIV-infected women based on the high risk in the excessively high TB incidence (more than 20-fold higher) in HIV-infected infants. Because scientists have improved techniques for isolating Mycobacterium tuberculosis in children and increasing the yield, it is possible to identify the strains from infected children, which can impact diagnosis and treatment. Our team has developed a protein-enriched broth that increases yield and decreases the time to detection. Pediatric TB also offers an opportunity to look at the emergence of drug resistant TB strains. In three DST surveys conducted in Cape Town (1997 through 2007) results indicated a significant increase in both drug and multi-drug resistant cases of TB in children. Examination of genotypes in 400 culture positive children showed the most prevalent form to be the Beijing strain, thought to have the greatest probability of progressing from TB infection to disease and with distinct disease forms. Programs to prevent TB and TB/HIV co-infection in children and adults must be improved; and safer vaccines, better diagnostics and shorter treatment regimens developed targeting children.

RT-PCR identification and genetic characterizations of VP1 region of human enterovirus 71 isolated in Beijing in 2008.

To study the genetic characterizations of VP1 region of Human enterovirus 71 (HEV71) isolated from clinical specimens of hand, foot and mouth disease (HFMD) patients in Beijing in 2008. 285 clinical samples were collected from HFMD patients in hospitals and day-care centers in Chaoyang district. They were performed by reverse transcription-polymerase chain reaction (RT-PCR) specific for HEV71. 10 HEV71 isolates were selected for entire VP1 coding gene amplification and sequencing. 129 samples were RT-PCR positive, the positive rate is 45.26%. The homology of the nucleotide and the amino acid of the 10 strains were 94.6%-99.6% and 95.9%-100%. The phylogenetic tree revealed that 10 Beijing strains clustered within the C4a evolution branch of C4 subgenotype. RT-PCR played an important role in identifying HFMD outbreak in Beijing in 2008. The HEV71 strains were all belong to C4a evolution branch of C4 subgenotype with several transmission chains, and it showed that C4 subgenotype HEV71 spread in mainland China widely after 1998. The molecular epidemiology surveillance and the research of genetic characterizations of HEV71 should be strengthened in mainland China.

Using a Label-free Proteomics Method to Identify Differentially Abundant Proteins in Closely Related Hypo- and Hypervirulent Clinical Mycobacterium tuberculosis Beijing Isolates

Although the genome of the Mycobacterium tuberculosis H37Rv laboratory strain has been available for over 10 years, it is only recently that genomic information from clinical isolates has been used to generate the hypothesis of virulence differences between different strains. In addition, the relationship between strains displaying differing virulence in an epidemiological setting and their behavior in animal models has received little attention. The potential causes for variation in virulence between strains, as determined by differential protein expression, have similarly been a neglected area of investigation. In this study, we used a label-free quantitative proteomics approach to estimate differences in protein abundance between two closely related Beijing genotypes that have been shown to be hyper- and hypovirulent on the basis of both epidemiological and mouse model studies. We were able to identify a total of 1668 proteins from both samples, and protein abundance calculations revealed that 48 proteins were over-represented in the hypovirulent isolate, whereas 53 were over-represented in the hypervirulent. Functional classification of these results shows that molecules of cell wall organization and DNA transcription regulatory proteins may have a critical influence in defining the level of virulence. The reduction in the presence of ESAT-6, other Esx-like proteins, and FbpD (MPT51) in the hypervirulent strain indicates that changes in the repertoire of highly immunogenic proteins can be a defensive process undertaken by the virulent cell. In addition, most of the previously well characterized gene targets related to virulence were found to be similarly expressed in our model. Our data support the use of proteomics as a complementary tool for genomic comparisons to understand the biology of M. tuberculosis virulence.

Mixed Infection with Beijing and Non-Beijing Strains and Drug Resistance Pattern of Mycobacterium tuberculosis

Mixed infection with Beijing and non-Beijing strains of Mycobacterium tuberculosis has been reported and has been suggested to mediate elevation of the reinfection rate in regions with a high incidence of tuberculosis (TB). To evaluate the prevalence of infection with both Beijing and non-Beijing strains of M. tuberculosis in eastern Taiwan, the region with the highest TB incidence in Taiwan, 185 active pulmonary TB patients were enrolled at Tzu Chi General Hospital from October 2007 to September 2008. A modified multiplex PCR method was developed to distinguish Beijing and non-Beijing strains directly using the sputum of patients. Of the 185 patients, 46.5% were infected with a Beijing strain, 42.2% were infected with a non-Beijing strain, and 11.3% were infected with both strain types. Notably, mixed infection with both strain types was not associated with TB treatment history or the high-incidence race group, aborigines. In addition, the incidence rate of mixed infection before treatment with anti-TB medication was as high as that in patients with a history of anti-TB treatment. Further analysis of antibiotic susceptibility revealed that Beijing strains alone had the highest multidrug resistance rate (17.5%), mixed infection had the highest rate of resistance to at least one drug (23.8%), and non-Beijing strains had the highest rate of sensitivity to all drugs (79.5%), implying that Beijing strains are predominant in the development of drug resistance in tuberculosis.

Molecular Detection of Mixed Infections of Mycobacterium tuberculosis Strains in Sputum Samples from Patients in Karonga District, Malawi

The occurrence of mixed infections of Mycobacterium tuberculosis is no longer disputed. However, their frequency, and the impact they may have on our understanding of tuberculosis (TB) pathogenesis and epidemiology, remains undetermined. Most previous studies of frequency applied genotyping techniques to cultured M. tuberculosis isolates and found mixed infections to be rare. PCR-based techniques may be more sensitive for detecting multiple M. tuberculosis strains and can be applied to sputum. To date, one study in South Africa has used a PCR approach and suggested that mixed infection could be common. We investigated mixed infections in northern Malawi using two lineage-specific PCR assays targeting the Latin American-Mediterranean (LAM) and Beijing lineages. Compared with spoligotyping, the specificity and sensitivity of both assays was 100%. From 160 culture-positive sputa, mixed LAM and non-LAM strains were detected in 4 sputa belonging to 2 (2.8%) patients. Both patients were HIV positive, with no history of TB. Cultured isolates from both patients showed only LAM by PCR and spoligotyping. In a set of 377 cultured isolates, 4 were mixed LAM and non-LAM. Only one showed evidence of more than one M. tuberculosis strain using IS6110-based restriction fragment length polymorphism (IS6110-RFLP) and spoligotyping analyses. Corresponding sputa for the 4 isolates were unavailable. Mixed Beijing and non-Beijing strains were not detected in this study. Mixed infections appear to be rare in our setting and are unlikely to affect findings based on DNA fingerprinting data. Molecular methods, which avoid the selective nature of culture and target distinct strains, are well suited to detection of mixed infections.

Molecular Characterization of Drug-Resistant Beijing Family Isolates of Mycobacterium Tuberculosis from Tianjin, China

Tuberculosis remains a severe public health issue, and the Beijing family of mycobacterium tuberculosis (M. tuberculosis) is widespread in East Asia, especially in some areas in China, like Beijing and Tianjin. This study aimed at determining the mutation patterns of drug-resistant Beijing strains of M. tuberculosis isolated from Tianjin, China. A total of 822 M. tuberculosis isolates were screened for drug resistance by an absolute concentration method and the genotype was identified by PCR. 169 drug-resistant isolates of the Beijing family were analyzed for the potential mutations in the rpoB, katG, inhA promoter region and in rpsL, rrs and embB genes, which are associated with resistance to rifampin (RFP), isoniazid (INH), streptomycin (SM) and ethambutol (EMB) respectively by PCR and DNA sequencing. Fifty-eight out of 63 RFP-resistant isolates were found to carry the mutations within the 81-bp RFP resistance determining region (RRDR) of the rpoB gene and the most frequent mutations occurred at codon 531 (44.4%), 526 (28.6%), and 516 (7.9%) respectively. 16 mutation patterns affecting 12 different codons around the RRDR of rpoB were found. Of 116 INH-resistant isolates, 56 (48.3%) had the mutation of katG 315 (AGC-->ACC) (Ser-->Thr), 3 (2.6%) carried S315N (AGC-->AAC) and 27 (16.0%) had the mutation of inhA-15A-->T. 84 out of 122 SM-resistant isolates (68.9%) displayed mutations at the codons 43 or 88 with AAG-->AGG (Lys-->Arg) of the rpsL gene and 22 (18.0%) with the mutations at positions 513A-->C, 516C-->T or 905 A-->G in the rrs gene. Of 34 EMB-resistant isolates, 6 had mutation with M306V (ATG-->GTG), 3 with M306I (ATG-->ATT), 1 with M306I (ATG-->ATA), 1 with D328Y (GAT-->TAT), 1 with V348L (GTC-->CTC), and 1 with G406S (GGC-->AGC) in the embB gene. These novel findings extended our understanding of resistance-related mutations in the Beijing strains of M. tuberculosis and may provide a scientific basis for development of new strategies for diagnosis and control of tuberculosis in China and other countries where Beijing strains are prevalent.

Drug Resistant Mycobacterium tuberculosis of the Beijing Genotype Does Not Spread in Sweden

BackgroundDrug resistant (DR) and multi-drug resistant (MDR) tuberculosis (TB) is increasing worldwide. In some parts of the world 10% or more of new TB cases are MDR. The Beijing genotype is a distinct genetic lineage of Mycobacterium tuberculosis, which is distributed worldwide, and has caused large outbreaks of MDR-TB. It has been proposed that certain lineages of M. tuberculosis, such as the Beijing lineage, may have specific adaptive advantages. We have investigated the presence and transmission of DR Beijing strains in the Swedish population.Methodology/Principal FindingsAll DR M. tuberculosis complex isolates between 1994 and 2008 were studied. Isolates that were of Beijing genotype were investigated for specific resistance mutations and phylogenetic markers. Seventy (13%) of 536 DR strains were of Beijing genotype. The majority of the patients with Beijing strains were foreign born, and their country of origin reflects the countries where the Beijing genotype is most prevalent. Multidrug-resistance was significantly more common in Beijing strains than in non-Beijing strains. There was a correlation between the Beijing genotype and specific resistance mutations in the katG gene, the mabA-inhA-promotor and the rpoB gene. By a combined use of RD deletions, spoligotyping, IS1547, mutT gene polymorphism and Rv3135 gene analysis the Beijing strains could be divided into 11 genomic sublineages. Of the patients with Beijing strains 28 (41%) were found in altogether 10 clusters (2–5 per cluster), as defined by RFLP IS6110, while 52% of the patients with non-Beijing strains were in clusters. By 24 loci MIRU-VNTR 31 (45%) of the patients with Beijing strains were found in altogether 7 clusters (2–11 per cluster). Contact tracing established possible epidemiological linkage between only two patients with Beijing strains.Conclusions/SignificanceAlthough extensive outbreaks with non-Beijing TB strains have occurred in Sweden, Beijing strains have not taken hold, in spite of the proximity to high prevalence countries such as Russia and the Baltic countries. The Beijing sublineages so far introduced in Sweden may not be adapted to spread in the Scandinavian population.

Characterization of Mycobacterium tuberculosis Beijing isolates from the Mediterranean area

BackgroundThe Beijing lineage of Mycobacterium tuberculosis is causing concern due to its global distribution and its involvement in severe outbreaks. Studies focused on this lineage are mainly restricted to geographical settings where its prevalence is high, whereas those in other areas are scarce. In this study, we analyze Beijing isolates in the Mediterranean area, where this lineage is not prevalent and is mainly associated with immigrant cases.ResultsOnly 1% (N = 26) of the isolates from two population-based studies in Spain corresponded to Beijing strains, most of which were pan-susceptible and from Peruvian and Ecuadorian patients. Restriction fragment length polymorphism typing with the insertion sequence IS6110 identified three small clusters (2-3 cases). Mycobacterial interspersed repetitive unit-variable number tandem repeat typing (MIRU-15) offered low discriminatory power, requiring the introduction of five additional loci. A selection of the Beijing isolates identified in the Spanish sample, together with a sample of Beijing strains from Italy, to broaden the analysis context in the Mediterranean area, were assayed in an infection model with THP-1 cells. A wide range of intracellular growth rates was observed with only two isolates showing an increased intracellular replication, in both cases associated with contained production of TNF-α. No correlation was observed between virulence and the Beijing phylogenetic group, clustered/orphan status, or resistance. The Beijing strain responsible for extensive spread on Gran Canaria Island was also identified in Madrid, but did not lead to secondary cases and did not show high infectivity in the infection model.ConclusionsThe Beijing lineage in our area is a non-homogeneous family, with only certain highly virulent representatives. The specific characterization of Beijing isolates in different settings could help us to accurately identify the virulent representatives before making general assumptions about this lineage.

Variation in Gamma Interferon Responses to Different Infecting Strains of Mycobacterium tuberculosis in Acid-Fast Bacillus Smear-Positive Patients and Household Contacts in Antananarivo, Madagascar

The majority of healthy individuals exposed to Mycobacterium tuberculosis will not develop tuberculosis (TB), though many may become latently infected. More precise measurement of the human immune response to M. tuberculosis infection may help us understand this difference and potentially identify those subjects most at risk of developing active disease. Gamma interferon (IFN-gamma) production has been widely used as a proxy marker to study infection and to examine the human immune response to specific M. tuberculosis antigens. It has been suggested that genetically distinct M. tuberculosis strains may invoke different immune responses, although how these differences influence the immune responses and clinical outcome in human tuberculosis is still poorly understood. We therefore evaluated the antigen-specific IFN-gamma production responses in peripheral blood mononuclear cells from two cohorts of subjects recruited in Antananarivo, Madagascar, from 2004 to 2006 and examined the influence of the infecting M. tuberculosis strains on this response. The cohorts were sputum-positive index cases and their household contacts. Clinical strains isolated from the TB patients were typed by spoligotyping. Comparison of the IFN-gamma responses with the spoligotype of the infecting clinical strains showed that "modern" M. tuberculosis strains, like Beijing and Central Asian (CAS) strains, tended to induce lower IFN-gamma responses than "ancient" strains, like East African-Indian (EAI) strains, in index cases and their household contacts. These results suggest that new strains may have evolved to induce a host response different from that of ancient strains. These findings could have important implications in the development of therapeutic and diagnostic strategies.

Emerging multidrug resistant Mycobacterium tuberculosis strains of the Beijing genotype circulating in Russia express a pattern of biological properties associated with enhanced virulence

The epidemiologically important Mycobacterium tuberculosis Beijing genotype strains, highly endemic in East Asia, have become an emerging infection in certain geographic areas, including Russia, because of its increasing prevalence and association with multidrug resistance (MDR). The aim was to verify whether MDR Beijing strains circulating in the emerging regions present some biological particularities that could contribute to their success in causing disease in comparison with the sporadic strains from locations with low prevalence of the Beijing genotype. We evaluated virulence-associated characteristics of the MDR Beijing strains isolated in Russia and compared them with those of the drug-resistant and susceptible Beijing strains from Brazil and reference H37Rv strain. We found that Russian MDR strains demonstrated an increased bacterial fitness and growth in THP-1 macrophage-like cells, as well as a higher capacity to induce non-protective cytokine synthesis and necrotic macrophage death. By contrast, the biological properties of the strains isolated in Brazil largely resembled those of the H37Rv strain, with the exception of the drug-resistant isolates that presented significantly reduced fitness. The data demonstrate that the emerging MDR strains of the Beijing genotype circulating in Russia do express a pattern of properties associated with the enhanced virulence favouring its clonal dissemination in this region.

Fatal congenital tuberculosis due to a Beijing strain in a premature neonate

Congenital tuberculosis (TB) remains a rare disease but is fatal if untreated. Early detection is difficult because of the non-specific nature of the symptoms in TB during pregnancy and infancy. This report summarizes a case of congenital TB in a very premature infant, born at 25 weeks gestation. Miliary TB was diagnosed in the mother when the neonate was 20 days old. Antituberculous therapy allowed a rapid improvement in the mother. The infant died at 27 days old. A Beijing genotype strain of Mycobacterium tuberculosis was isolated both in the mother, from pulmonary and urine specimens, and in the infant, from peritoneal fluid.

Adhesion to and invasion of pulmonary epithelial cells by the F15/LAM4/KZN and Beijing strains of Mycobacterium tuberculosis

Globally, specific genotypes of Mycobacterium tuberculosis have been shown to dominate in patients, suggesting that these are more successful pathogens. One such genotype, the F15/LAM4/KZN (KZN) family of M. tuberculosis, has predominated in KwaZulu-Natal, South Africa, since the early 1990s. This strain recently evolved from multidrug-resistant to extensively drug-resistant (XDR). The ability of M. tuberculosis strains belonging to the Beijing family, the KZN family, strains with unique DNA fingerprint patterns and laboratory strains (H37Rv and H37Ra) to adhere to and invade a human alveolar (A549) and a human bronchial (BBM) epithelial cell line was investigated. All strains displayed greater adhesion to and invasion of A549 cells as compared to BBM cells. The Beijing and KZN strains combined showed greater adhesion (28 %) than the unique strains (5 %) (P <0.05). The XDR variant of KZN invaded A549 cells more effectively than the other isolates. These results suggest that the successful spread of the Beijing and KZN strains might be related to their interaction with alveolar epithelium.

Effect of serial subculturing on the genetic composition and cytotoxicactivity of Mycobacterium tuberculosis

Continuous subculture has been observed to produce changes in the virulence of micro-organisms, e.g. rabies virus, poliovirus and Mycobacterium bovis BCG. The latter has been used as a vaccine for tuberculosis for the last 100 years; however, in some instances its efficacy has been observed to be very low. In order to determine whether similar changes can be produced in Mycobacterium tuberculosis, we selected four isolates, M. tuberculosis H37Rv, a Beijing strain (DR-689), and two more isolates with deletion of the phospholipase C locus (plcA-plcB-plcC ), and subjected them to serial culturing on Middlebrook 7H9 medium, with or without ox bile. After 100 passages, we performed RFLP-IS6110 analysis to determine whether genomic changes were produced. We also checked their genomic composition by microarray analysis. Changes in virulence were studied by measuring the cytotoxic effect of parental and subcultured isolates on a THP-1 macrophage monolayer. The most visible change was the change of position of an IS6110 band of approximately 1400 bp to approximately 1600 bp in the Beijing isolate subcultured in the ox bile medium. Analysis by microarray and PCR confirmation did not reveal any genomic changes. Cytotoxic activity was decreased in the isolates at levels close to that of BCG, and more consistently in those subcultured in the presence of ox bile.

Peritonitis tuberculosa: revisión de 16 años en un hospital general

Peritoneal tuberculosis (PT) is a form of abdominal tuberculosis that accounts for 1%-3% of all cases of tuberculous disease and often manifests with non-specific symptoms. Cases of PT diagnosed over a period of 16 years are reviewed and the epidemiological, clinical, diagnostic, and outcome data are analyzed. Among 462 patients with extrapulmonary tuberculosis, PT was documented in 13 patients (2.8%), only one whom was infected by human immunodeficiency virus. In most patients, the diagnosis was established on histological findings. In 5 cases, ascitic fluid culture was positive, and the diagnosis was established by this method alone in 3 of them. A multidrug-resistant Mycobacterium tuberculosis Beijing strain was isolated in one patient. The remaining strains isolated were sensitive to classic antituberculosis drugs. Ten patients were treated with 3 antituberculosis agents and 2 were treated with 4 drugs. Eight patients progressed favorably and 5 died due to complications of their underlying medical conditions. Peritoneal tuberculosis can develop without evidence of concomitant tuberculous disease. Histology is usually needed to confirm the diagnosis, and the prognosis is good with prompt treatment.

Comparison of genotype characteristics between the circulating mumps virus strain in Beijing area and the vaccine strain

To compare the genetic characteristics of mumps virus strain circulating in Beijing with vaccine strain and to preliminarily analysis the reasons of vaccine ineffectiveness. The following methods were used: Isolation and identification of the mumps virus which had been circulating in Beijing, immunization history analysis, SH gene sequence analysis and comparison genotype homology with reference strains and analysis of the key amino acid sites of HN variation. In 38 mumps cases that virus had been isolated from, another seven cases were IgM negative. In 2007 and 2008, the positive rates on virus isolation, RT-PCR and IgM-decreased significantly, while the cases with immunization history had an increase. Cases without histories of vaccination had both higher positive rates on virus isolation and IgM. Thirty-eight strains belonged to F genotype virus, but vaccine strain was A genotype. The circulating viruses showed 5.6% sequence divergence on SH gene nucleotide and 16.0% - 18.1% from vaccine strain. Conservative hydrophobic amino acids on SH protein of some Beijing strains had changed. For example, there were 6 strains, from No.8: L-->F. The circulating viruses showed 2.3% sequence divergence on HN protein amino acid sequences and 4.2% - 5.3% from vaccine strain. Amino acids sites, which deciding the ability of cross-neutralization of the Beijing strains and vaccine strains were different. At the 354 and 356 sites, all the Beijing strains were different from the vaccine strains. The N-glycosylation sites on HN of Beijing strains were also different from those on vaccine strains. Locations 464 - 466 appeared to be NCS on Beijing strain, but locations 464 - 466 were NCR on the vaccine strains. Another 18 unknown function amino acids sites of all Beijing strains were different from those on vaccine strains. In recent years, genotype F became the main genotype of circulating strains in Beijing without genotype variation, but larger difference was found between them. There was a big difference between SH and HN protein of Beijing strains and vaccine strain, which might explain the ineffectiveness of the vaccine.

A Lipid Profile Typifies the Beijing Strains of Mycobacterium tuberculosis: IDENTIFICATION OF A MUTATION RESPONSIBLE FOR A MODIFICATION OF THE STRUCTURES OF PHTHIOCEROL DIMYCOCEROSATES AND PHENOLIC GLYCOLIPIDS

The Mycobacterium tuberculosis Beijing strains are a family highly prevalent in Asia and have recently spread worldwide, causing a number of epidemics, suggesting that they express virulence factors not found in other M. tuberculosis strains. Accordingly, we looked for putative characteristic compounds by comparing the lipid profiles of several Beijing and non-Beijing strains. All the Beijing strains analyzed were found to synthesize structural variants of two well known characteristic lipids of the tubercle bacillus, namely phthiocerol dimycocerosates (DIM) and eventually phenolglycolipids (PGL). These variants were not found in non-Beijing M. tuberculosis isolates. Structural elucidation of these variants showed that they consist of phthiotriol and glycosylated phenolphthiotriol dimycocerosates, eventually acylated with 1 mol of palmitic acid, in addition to the conventional acylation of the beta-diol by mycocerosic acids. We demonstrated that this unusual lipid profile resulted from a single point mutation in the Rv2952 gene, which encodes the S-adenosylmethionine-dependent methyltransferase participating to the O-methylation of the third hydroxyl of the phthiotriol and phenolphthiotriol in the biosynthetic pathway of DIM and PGL. Consistently, the mutated enzyme exhibited in vitro a much lower O-methyltransferase activity than did the wild-type Rv2952. We finally demonstrated that the structural variants of DIM and PGL fulfill the same function in the cell envelope and virulence than their conventional counterparts.

Mycobacterium tuberculosisGenotype and Case Notification Rates, Rural Vietnam, 2003–2006

Tuberculosis case notification rates (CNRs) for young adults in Vietnam are increasing. To determine whether this finding could reflect emergence of Mycobacterium tuberculosis Beijing genotype, we studied all new sputum smear-positive pulmonary tuberculosis patients registered for treatment in 3 rural districts in Vietnam during 2003-2006. Beijing strain infections were more frequent in younger patients (15-24 years of age, 53%) than in older patients (31%; p<0.001). The increase in CNRs for youngest patients was larger for disease caused by the Beijing genotype than by other genotypes, but the difference was not significant. For patients 15-24 years of age, 85% of fluctuations in CNRs between years was caused by fluctuations in Beijing genotype infections compared with 53% and 23% in the groups 25-64 and >or=65 years of age, respectively (p<0.001). These findings suggest that young adults may be responsible for introducing Beijing strains into rural Vietnam.

Penitentiary population of Mycobacterium tuberculosis in Kyrgyzstan: Exceptionally high prevalence of the Beijing genotype and its Russia-specific subtype

Here, we present results of the first study of the Mycobacterium tuberculosis genotypes circulating in Kyrgyzstan. We focused on the incarcerated population known to be at high-risk for tuberculosis (TB) and with a significant impact on TB incidence in the general population. Beijing genotype was detected in 42 of 56 M. tuberculosis sputum-extracted DNA samples from newly-diagnosed adult pulmonary TB patients. RIF and INH resistance was genotypically detected in 28% and 55% samples; 13 of 15 MDR strains belonged to Beijing genotype. 12-locus MIRU-VNTR typing showed 8 of 56 samples to be mixed cases; 7 of them contained a Beijing strain. MIRU analysis demonstrated a high homogeneity of the studied collection (HGI = 0.66) while 28 of 56 strains had a profile 223325153533 corresponding to Beijing/M2 subtype highly prevalent in different Russian settings. Three hypervariable loci, QUB-3232, VNTR-3820 and VNTR-4120, permitted to further subdivide 28 Beijing/M2 strains into 11 subtypes shared by 1 to 9 strains. To conclude, all markers taken together, the penitentiary population of M. tuberculosis in Kyrgyzstan exhibited a strong genetic affinity to Russia and a weak relatedness to East Asia.

Relapse Associated with Active Disease Caused by Beijing Strain ofMycobacterium tuberculosis1

The role of microbial factors in outcomes of tuberculosis treatment has not been well studied. We performed a case-control study to evaluate the association between a Beijing strain and tuberculosis treatment outcomes. Isolates from patients with culture-positive treatment failure (n = 8) or relapse (n = 54) were compared with isolates from randomly selected controls (n = 296) by using spoligotyping. Patients with Beijing strains had a higher risk for relapse (odds ratio [OR] 2.0, 95% confidence interval [CI] 1.0-4.0, p = 0.04) but not for treatment failure. Adjustment for factors previously associated with relapse had little effect on the association between Beijing strains and relapse. Beijing strains were strongly associated with relapse among Asian-Pacific Islanders (OR 11, 95% CI 1.1-108, p = 0.04). Active disease caused by a Beijing strain was associated with increased risk for relapse, particularly among Asian-Pacific Islanders.

Possible Outbreak of Streptomycin-ResistantMycobacterium tuberculosisBeijing in Benin

Using geographic information system and molecular tools, we characterized a possible outbreak of tuberculosis caused by Mycobacterium tuberculosis Beijing strain in 17 patients in Cotonou, Benin, during July 2005–October 2006. Most patients lived or worked in the same area and frequented the same local drinking bar. The isolates were streptomycin resistant.