Survey of drug-resistant tuberculosis in northwestern Russia from 1984 through 1994

Infectivity of Mycobacterium tuberculosis Genotypes and Outcome of Contact Investigation in Classroom in Guangxi, China

OBJECTIVE

To evaluate the infectivity of Mycobacterium tuberculosis (M.tb) genotypes of index cases in the classroom of adolescent schools in Guangxi, China.

METHODS

Adolescent school tuberculosis (TB) contact investigations were conducted for all reported index TB cases from November 2016 to December 2017 in Guangxi, China. Genotypes of index cases and contact cases were identified by 15-loci mycobacterial interspersed repetitive units-variable number tandem repeat and spoligotyping. Outcome variable was 5 levels' order of tuberculin skin test (TST) results to new active TB [0-5 mm, 6-9 mm, 10-14 mm, ≥ 15 mm (without TB), and ≥15 mm (with TB)]. Multivariate ordered logistic regression analysis was performed to evaluate the independent effect of genotypes of index case on contact screening outcome.

RESULTS

Beijing genotype occurred more commonly in female index patients. One genotypic cluster of two index cases and one cluster of two contact cases were detected. The association between infectivity of Beijing genotype of index cases and outcome of contact investigation was statistically significant in univariate analysis but no so after adjustment for characteristics of contacts and sex of index cases (P value=0.057). Female index cases increased the chance for TB infection/being active TB among contacts (ordinal odds ratio = 1.39, 95% confidence interval: 1.21, 1.60). Contacts who studied in the middle school, who with non-Han ethnicity and who without BCG scar had increased risk for TB infection/being active TB.

CONCLUSION

There was not enough evidence from our data to support that Beijing strains were more infective than non-Beijing strains in TB transmission in school setting.

The re-emergence of tuberculosis: what have we learnt from molecular epidemiology?

Tuberculosis (TB) has re-emerged over the past two decades: in industrialized countries in association with immigration, and in Africa owing to the human immunodeficiency virus epidemic. Drug-resistant TB is a major threat worldwide. The variable and uncertain impact of TB control necessitates not only better tools (diagnostics, drugs, and vaccines), but also better insights into the natural history and epidemiology of TB. Molecular epidemiological studies over the last two decades have contributed to such insights by answering long-standing questions, such as the proportion of cases attributable to recent transmission, risk factors for recent transmission, the occurrence of multiple Mycobacterium tuberculosis infection, and the proportion of recurrent TB cases attributable to re-infection. M. tuberculosis lineages have been identified and shown to be associated with geographical origin. The Beijing genotype is strongly associated with multidrug resistance, and may have escaped from bacille Calmette-Guérin-induced immunity. DNA fingerprinting has quantified the importance of institutional transmission and laboratory cross-contamination, and has helped to focus contact investigations. Questions to be answered in the near future with whole genome sequencing include identification of chains of transmission within clusters of patients, more precise quantification of mixed infection, and transmission probabilities and rates of progression from infection to disease of various M. tuberculosis lineages, as well as possible variations in vaccine efficacy by lineage. Perhaps most importantly, dynamics in the population structure of M. tuberculosis in response to control measures in high-prevalence areas should be better understood.

Extremely high prevalence of multidrug resistant tuberculosis in Murmansk, Russia: a population-based study

Drug resistance and molecular epidemiology of tuberculosis (TB) in the Murmansk region was investigated in a 2-year, population-based surveillance of the civilian population. During 2003 and 2004, isolates from all culture-positive cases were collected (n = 1,226). Prevalence of multi-drug resistance (MDR) was extremely high, as 114 out of 439 new cases (26.0%), and 574 out of 787 previously treated cases (72.9%) were resistant to at least isoniazid (INH) and rifampin (RIF). Spoligotyping of the primary MDR-TB isolates revealed that most isolates grouped to the Beijing SIT1 genotype (n = 91, 79.8%). Isolates of this genotype were further analyzed by IS6110 RFLP. Sequencing of gene targets associated with INH and RIF resistance further showed that the MDR-TB strains are highly homogeneous as 78% of the MDR, SIT1 strains had the same resistance-conferring mutations. The genetic homogeneity of the MDR-TB strains indicates that they are actively transmitted in Murmansk.

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.

Rolling circle amplification and multiplex allele-specific PCR for rapid detection of katG and inhA gene mutations in Mycobacterium tuberculosis

The aim of the study was to compare a novel, rolling circle amplification (RCA) assay for detection of common isoniazid (INH) resistance mutations in Mycobacterium tuberculosis with a multiplex allele-specific PCR (MAS-PCR) and sequencing of katG and the fabG1-inhA promoter region. One or more mutations were identified by RCA, MAS-PCR, and sequencing in 21 (68%), 22 (71%), and 23 (74%), respectively, of 31 epidemiologically unrelated INH-resistant isolates, and in none of 8 INH-susceptible isolates. The RCA assay is a rapid, inexpensive, and practical screening method for INH resistance in M. tuberculosis in countries with high prevalence of INH resistance.

Tuberculosis in St. Petersburg and the Baltic Sea region

Tuberculosis (TB) remains a global public health concern and challenges the national structures for infection control and health care, as well as international institutions, to develop and implement new strategies to control and combat this disease. In our report, we investigated the TB epidemiological situation in St. Petersburg and the countries around the Baltic Sea using national epidemiological statistics and epidemiological reports of international organizations, such as the WHO and Euro-TB. After the disintegration of the Soviet Union, a steep increase in tuberculosis was seen in the Russian Federation, St. Petersburg and the Baltic States, after which it stabilized at levels significantly higher compared to the Nordic countries. Moreover, the epidemiological situation in St. Petersburg and the Baltic States was aggravated by the emergence and spread of TB/HIV coinfection, as well as that of drug-resistant M. tuberculosis, which imposed further difficulties in gaining control of TB. During the studied period, the TB burden in neither St. Petersburg nor Baltic States has had a significant impact on the epidemiology in the low TB burden neighbouring countries around the Baltic Sea.

At Baltic crossroads: a molecular snapshot of Mycobacterium tuberculosis population diversity in Kaliningrad, Russia

The Kaliningrad region is the westernmost part of the Russian Federation; it includes an enclave on the Baltic Sea inside the European Union separated from mainland Russia by Lithuania and Poland. The incidence of tuberculosis in Kaliningrad has shown a steady and dramatic increase from 83/100,000 in 2000 to 134/100,000 in 2006; the rate of multidrug-resistant tuberculosis (MDR-tuberculosis) in the Kaliningrad region was reported to be 30.5% among newly diagnosed tuberculosis patients. This study presents a first molecular snapshot of the population diversity of Mycobacterium tuberculosis in this region. A total of 90 drug-resistant and susceptible M. tuberculosis strains from Kaliningrad were subjected to spoligotyping, 12-locus MIRU typing and mutation analysis of the drug resistance genes rpoB and katG. A comparison with international databases showed that the M. tuberculosis population in this region shares a joint pool of strains with the European part of Russia, and also exhibits a certain affinity with those of its northern European neighbours, such as Poland and Germany. Comparison of the genotyping and drug resistance data emphasized that the high prevalence of the MDR Beijing genotype strains is a major cause of the adverse epidemiological situation of MDR-tuberculosis in the Kaliningrad region.

Epidemic of tuberculosis in the former Soviet Union: social and biological reasons

The tuberculosis epidemic was evidenced in the states of the former Soviet Union at the end of the 20th century. The increase of epidemiological indicators for tuberculosis was accelerated by socio-economic changes in the society. Laboratory analysis also revealed new biological properties of the Mycobacterium tuberculosis isolates in the region, in particular the high level of resistance to antibiotics. Tuberculosis in Russia and the other newly independent states has been caused by M. tuberculosis strains of the W-Beijing family in recent years. These bacteria have rapidly developed resistance to anti-tuberculosis drugs, as a result of prolonged exposure of the patients to inappropriate treatment. The epidemic of drug-resistant tuberculosis caused by the W-Beijing strains represents an important threat to the health of the populations in the newly independent states. It may also adversely affect the global trends in tuberculosis, as there is a clear risk that these drug-resistant strains can spread to other communities outside the former Soviet Union.

Multidrug-resistant tuberculosis in Russia: clinical characteristics, analysis of second-line drug resistance and development of standardized therapy

The aim of the study presented here was to identify patients with multidrug resistant tuberculosis (MDRTB) in the Samara region of Russia and to analyze the susceptibility of their isolates to second-line drugs in order to develop an empirical, standard, second-line treatment regimen. Treatment of MDRTB can be individualized based on in vitro laboratory analysis or standardized. In the latter case there is still a need to ascertain local second-line drug-resistance patterns. Described here are the clinical characteristics of 251 MDRTB patients identified in the study and the second-line drug susceptibility of 69 MDRTB isolates obtained from them. Antimicrobial resistance to the following agents was detected in the isolates: rifabutin (88.2%), streptomycin (42.8%), amikacin (7.2%), doxycycline (7.4%), ciprofloxacin (4.3%), clofazimine (2.9%), cycloserine (7.4%), and prothionamide (1.5%). The results of the study indicate it is possible to develop a standard, effective, clinical treatment regimen using ethambutol, pyrazinamide, prothionamide, a fluoroquinolone and amikacin.

Rates of drug resistance and risk factor analysis in civilian and prison patients with tuberculosis in Samara Region, Russia

BACKGROUND

Tuberculosis (TB) and HIV rates continue to escalate in Russia, but true rates for drug resistance, especially multidrug resistant tuberculosis (MDR TB), are unknown. A study was conducted with the aims of identifying first line drug resistance, both in the civilian and prison sectors, for new and previously treated cases; and risk factors for the development of drug resistance.

METHODS

A cross sectional survey was undertaken of 600 patients (309 civilians, 291 prisoners) with bacteriologically confirmed pulmonary TB over a 1 year period during 2001-2 in Samara Oblast, Russia.

RESULTS

The prevalence of isoniazid, rifampicin, streptomycin, ethambutol and pyrazinamide resistance in new TB cases (civilian and prison patients) was 38.0%, 25.2%, 34.6%, 14.7%, and 7.2%, respectively. The prevalence of MDR TB was 22.7%, 19.8%, and 37.3% in all new cases, new civilian cases, and new prison cases, respectively, with an overall prevalence of 45.5% and 55.3% in previously treated cases. Factors associated with resistance included previous TB treatment for more than 4 weeks, smoking (for isoniazid resistance), the presence of cavitations on the chest radiograph, and imprisonment. HIV was not associated with resistance in all patients. The rates of resistance were significantly higher in prisoners, with rate ratios (RR) of 1.9 (95% CI 1.1 to 3.2) for MDR TB, 1.9 (95% CI 1.1 to 3.2) for rifampicin, and 1.6 (95% CI 1.0 to 2.6) for isoniazid.

CONCLUSIONS

Rates of first line drug resistance are high, particularly in prisoners and previously treated cases. TB control programmes should initially focus on standardised treatment to maximise cure, combined with measures to reduce institutional TB spread (particularly in prisons) coupled with early diagnosis of MDR TB to reduce the spread and development of resistance.

Allele-specific rpoB PCR assays for detection of rifampin-resistant Mycobacterium tuberculosis in sputum smears

We describe an allele-specific PCR assay to detect mutations in three codons of the rpoB gene (516, 526, and 531) in Mycobacterium tuberculosis strains; mutations in these codons are reported to account for majority of M. tuberculosis clinical isolates resistant to rifampin (RIF), a marker of multidrug-resistant tuberculosis (MDR-TB). Three different allele-specific PCRs are carried out either directly with purified DNA (single-step multiplex allele-specific PCR), or with preamplified rpoB fragment (nested allele-specific PCR [NAS-PCR]). The method was optimized and validated following analysis of 36 strains with known rpoB sequence. A retrospective analysis of the 287 DNA preparations from epidemiologically unlinked RIF-resistant clinical strains from Russia, collected from 1996 to 2002, revealed that 247 (86.1%) of them harbored a mutation in one of the targeted rpoB codons. A prospective study of microscopy-positive consecutive sputum samples from new and chronic TB patients validated the method for direct analysis of DNA extracted from sputum smears. The potential of the NAS-PCR to control for false-negative results due to lack of amplification was proven especially useful in the study of these samples. The developed rpoB-PCR assay can be used in clinical laboratories to detect RIF-resistant and hence MDR M. tuberculosis in the regions with high burdens of the MDR-TB.

PCR-based methodology for detecting multidrug-resistant strains of Mycobacterium tuberculosis Beijing family circulating in Russia

The Beijing genotype of Mycobacterium tuberculosis has been identified in 40-50% of the clinical isolates studied in Russia during the last decade. This genotype has been reported to be associated with multiple drug resistance and possesses some significant pathogenic properties. Therefore, early identification of such strains is of extreme importance in the timely detection of drug resistance. The present study was performed on 354 strains isolated in Russia from 1996 to 2002 and previously characterised by IS 6110-restriction fragment length polymorphism (RFLP) typing and spoligotyping. These strains included 198 Beijing family strains and 156 strains of other genotypes (IS 6110-RFLP profiles). A subsequent polymerase chain reaction (PCR) analysis with IS 6110-derived outwardly oriented primers (IS 6110-PCR) easily discriminated the Beijing strains from non-Beijing strains. The multiplex allele-specific (MAS)-PCR assays were further used to detect mutations in katG315 and rpoB531, associated with resistance to isoniazid and rifampin, respectively. The katG315 and rpoB531 mutations were found to be more prevalent among Beijing (96.8% and 77.3%) than among non-Beijing strains (85.7% and 28%). Consequently, we propose a two-step methodology based on routine PCR and simple agarose gel electrophoresis in order to detect (i) a Beijing family strain using IS 6110-PCR, and, (ii) its possible resistance to the major anti-tuberculosis drugs using specific MAS-PCR assays.

Detection of embB306 mutations in ethambutol-susceptible clinical isolates of Mycobacterium tuberculosis from Northwestern Russia: implications for genotypic resistance testing

A total of 183 epidemiologically unlinked Mycobacterium tuberculosis isolates collected in the St. Petersburg area of Russia from 1996 to 2001 were screened for alterations in codon 306 of the embB gene; mutations in this codon are reported to confer resistance to ethambutol (EMB). The embB306 mutations were detected in 14 (48.3%) of 29 EMB-resistant strains and, quite surprisingly, in 48 (31.2%) of 154 EMB-susceptible strains. A discrepancy between the results of phenotypic and genotypic EMB resistance tests was restricted to the strains already resistant to other antitubercular (anti-TB) drugs. In particular, 40 (60%) of the 69 EMB-susceptible strains resistant to rifampin, isoniazid, and streptomycin but none of the 43 pansusceptible strains harbored an embB306 mutation. We hypothesize that the phenomenon observed could reflect the presence of a target other than EmbB for the drug in tubercle bacilli; this unknown target could be sensitized and affected, sensu lato, by EMB during treatment with other first-line anti-TB drugs. Comparison with DNA fingerprinting data showed that, irrespectively of the phenotypic susceptibility profiles, 46 (50.6%) of 91 Beijing family strains and 16 (17.4%) of 92 strains of other genotypes had a mutation in embB306.

Tuberculosis therapy and telemedicine

Directly observed therapy (DOT) ensures patient adherence through the administration of medications by trained health department personnel. This approach has been widely adopted in tuberculosis care. Unfortunately, DOT programs require a substantial commitment of scarce public health funds and personnel time. The application of telemedicine to DOT promises considerable cost and time savings.

Detection of isoniazid-resistant Mycobacterium tuberculosis strains by a multiplex allele-specific PCR assay targeting katG codon 315 variation

We describe a simple multiplex allele-specific (MAS)-PCR assay to detect mutations in the second base of the katG gene codon 315, including AGC-->ACC and ACA (Ser-->Thr) substitutions that confer resistance to isoniazid (INH) in Mycobacterium tuberculosis clinical isolates. The 315 ACC allele is found in the majority of Inh(r) strains worldwide, especially in areas with a high incidence of tuberculosis. The 315 ACA allele is characteristic of the New York City multidrug-resistant (MDR) strain W and its progenies in the United States. The mutations in katG315 are revealed depending on the presence or absence of an indicative fragment amplified from the wild-type allele of this codon. Initially optimized on the purified DNA samples, the assay was then tested on crude cell lysates and auramine-stained sputum slide preparations with the same reproducibility and interpretability of profiles generated by agarose gel electrophoresis. The MAS-PCR assay can be used for the detection of resistance to INH in clinical laboratories in regions with a high prevalence of MDR M. tuberculosis strains.

High prevalence of KatG Ser315Thr substitution among isoniazid-resistant Mycobacterium tuberculosis clinical isolates from northwestern Russia, 1996 to 2001

A total of 204 isoniazid (INH)-resistant strains of Mycobacterium tuberculosis isolated from different patients in the northwestern region of Russia from 1996 to 2001 were screened by a PCR-restriction fragment length polymorphism (RFLP) assay. This assay uses HapII cleavage of an amplified fragment of the katG gene to detect the transversion 315AGC-->ACC (Ser-->Thr), which is associated with INH resistance. This analysis revealed a 93.6% prevalence of the katG S315T mutation in strains from patients with both newly and previously diagnosed cases of tuberculosis (TB). This mutation was not found in any of 57 INH-susceptible isolates included in the study. The specificity of the assay was 100%; all isolates that contained the S315T mutation were classified as resistant by a culture-based susceptibility testing method. The Beijing genotype, defined by IS6110-RFLP analysis and the spacer oligonucleotide typing (spoligotyping) method, was found in 60.3% of the INH-resistant strains studied. The katG S315T shift was more prevalent among Beijing genotype strains than among non-Beijing genotype strains: 97.8 versus 84.6%, respectively, for all isolates, including those from patients with new and previously diagnosed cases, isolated from 1999 to 2001 and 100.0 versus 86.5%, respectively, for isolates from patients with new cases isolated from 1996 to 2001. The design of this PCR-RFLP assay allows the rapid and unambiguous identification of the katG 315ACC mutant allele. The simplicity of the assay permits its implementation into routine practice in clinical microbiology laboratories in regions with a high incidence of TB where this mutation is predominant, including northwestern Russia.

Detection of ethambutol-resistant Mycobacterium tuberculosis strains by multiplex allele-specific PCR assay targeting embB306 mutations

We describe a multiplex allele-specific (MAS)-PCR assay to detect simultaneously mutations in the first and third bases of the embB gene codon 306ATG. These mutations are known to confer ethambutol (EMB) resistance in the majority of clinical Mycobacterium tuberculosis isolates worldwide. The mutated bases are revealed depending on the presence or absence of the respective indicative fragments amplified from the embB306 wild-type allele. Initially optimized on purified DNA samples, the assay was tested on crude cell lysates and auramine-stained sputum slide DNA preparations with the same reproducibility and interpretability of the generated profiles in agarose gel electrophoresis. Since EMB resistance is generally linked to multiple-drug resistance (MDR), the MAS-PCR assay for EMB resistance detection can be used in clinical laboratory practice in areas with a high prevalence and a high transmission rate of MDR-EMB-resistant tuberculosis.

Prevalence of infectious diseases among internationally adopted children

OBJECTIVE

Internationally adopted children are at increased risk of infections acquired in their country of origin. Ongoing surveillance of this unique population is needed to detect changing epidemiology and provide appropriate care.

METHODS

We performed a retrospective cohort study of 504 children adopted from abroad and evaluated from 1997 to 1998 to determine the prevalence of and factors associated with various infectious diseases.

RESULTS

The mean age of the study participants at medical evaluation was 1.6 years; 71% were girls, and they were adopted from 16 countries, including China (48%), Russia (31%), Southeast Asia (8%), Eastern Europe (8%), and Latin America (5%). Overall, 75 (19%) of 404 children tested had tuberculin skin tests >/=10 mm, but all had normal chest radiographs. BCG vaccination (odds ratio [OR]: 7.37; 95% confidence interval [CI]: 3.29, 17.16) and being Russian born (OR: 2.90; 95% CI: 1.68, 5.00) were risk factors for latent tuberculosis infection. Fourteen (2.8%) children had detectable hepatitis B surface antigen, but no child had active hepatitis C, human immunodeficiency virus, or syphilis. Giardia lamblia antigen was detected in 87 (19%) of 461 tested children, and such children were older (mean: 22 months vs 15.5 months) and more likely to have been born in Eastern Europe (OR: 2.82; 95% CI: 1.70, 4.68).

CONCLUSIONS

We demonstrated increased rates of latent tuberculosis infection and G lamblia infection than previously reported. Thus, ongoing surveillance of internationally adopted children, international trends in infectious diseases, and appropriate screening will ensure the long-term health of adopted children as well as their families.

Epidemiology and ethnic distribution of multidrug-resistant tuberculosis in southern Israel, 1992-1997: the impact of immigration

STUDY OBJECTIVES

To assess the incidence of tuberculosis in the native and immigrant populations of southern Israel in the period between 1992 and 1997, and to study the prevalence of drug resistance overall and among these subpopulations in the region in order to create guidelines for empirical antituberculous treatment in this region.

DESIGN

A retrospective population-based study.

SETTING

The southern district of the country and its tertiary-care hospital.

PATIENTS

All new culture-proven tuberculosis cases diagnosed in adults residing in the Negev region during the study period. Patients were classified into four groups according to ethnic origin and immigration date.

RESULTS

During the study period, 249 new cases involving 249 patients were recorded. Immigrants from the former Soviet Union (IFSU) were significantly younger and of male gender, and the incidence among this group rose sharply. IFSU had higher rates of resistance to any drug or drug combination. Isoniazid resistance rates were 16% overall and 32% among IFSU. Resistance to any drug was observed in 29% overall and 50% of isolates among IFSU. Multidrug-resistant tuberculosis was observed in 8.5% and 17%, respectively.

CONCLUSIONS

The population of southern Israel carries very high rates of drug-resistant tuberculosis, mandating quadruple empiric treatment. IFSU should be regarded as having multidrug-resistant tuberculosis until proven otherwise, and empiric therapy with at least five drugs should be considered. This report demonstrates the influence of immigration on the incidence of tuberculosis, and the great value of local surveillance of population-specific resistance rates in an immigrant society, in order to optimize drug treatment and prevent the dissemination of resistant strains.

Childhood tuberculosis--problems ahead

Childhood tuberculosis (TB) is on the increase, both in developing countries and in the UK. Children cannot usually be diagnosed as having TB by sputum microscopy and culture alone, so millions of children are destined to die of undiagnosed TB in poor countries. Drug resistance is likely to affect a greater proportion of TB cases in children, because they have been recently infected by adults. Whilst BCG vaccination can protect against miliary TB and TB meningitis, it will not interrupt the chain of transmission. HIV co-infected mothers are capable of passing congenital TB to their children.