Performance of spirometry assessment at TB diagnosis

BACKGROUND: Spirometry is considered relevant for the diagnosis and monitoring of post-TB lung disease. However, spirometry is rarely done in newly diagnosed TB patients.METHODS: Newly diagnosed, microbiologically confirmed TB patients were recruited for the study. Spirometry was performed within 21 days of TB treatment initiation according to American Thoracic Society/European Respiratory Society guidelines. Spirometry analysis was done using Global Lung Initiative equations for standardisation.RESULTS: Of 1,430 eligible study participants, 24.7% (353/1,430) had no spirometry performed mainly due to contraindications and 23.0% (329/1,430) had invalid results; 52.3% (748/1,430) of participants had a valid result, 82.8% (619/748) of whom had abnormal spirometry. Of participants with abnormal spirometry, 70% (436/619) had low forced vital capacity (FVC), 6.1% (38/619) had a low ratio of forced expiratory volume in 1 sec (FEV1) to FVC, and 19.1% (118/619) had low FVC, as well as low FEV1/FVC ratio. Among those with abnormal spirometry, 26.3% (163/619) had severe lung impairment.CONCLUSIONS: In this population, a high proportion of not performed and invalid spirometry assessments was observed; this was addressed by removing tachycardia as a (relative) contraindication from the study guidance and retraining. The high proportion of patients with severe pulmonary impairment at the time of TB diagnosis suggests a huge morbidity burden and calls for further longitudinal studies on the relevance of spirometry in predicting chronic lung impairment after TB.

Multicentre study to establish interpretive criteria for clofazimine drug susceptibility testing

<sec id="st1"> <title>OBJECTIVE</title> To conduct a multicentre study to establish the critical concentration (CC) for clofazimine (CFZ) for drug susceptibility testing (DST) of Mycobacterium tuberculosis on the MGIT™960™ system using the distribution of minimum inhibitory concentrations (MIC) and genotypic analyses of Rv0678 mutations. </sec> <sec id="st2"> <title>DESIGN</title> In phase I of the study, the MIC distribution of laboratory strains (H37Rv and in vitro-selected Rv0678 mutants) and clinical pan-susceptible isolates were determined (n = 70). In phase II, a tentative CC for CFZ (n = 55) was proposed. In phase III, the proposed CC was validated using clinical drug-resistant tuberculosis (DR-TB) isolates stratified by Rv0678 mutation (n = 85). </sec> <sec id="st3"> <title>RESULTS AND CONCLUSION</title> The MIC distribution of CFZ for laboratory and clinical pan-susceptible strains ranged between 0.125 μg/ml and 0.5 μg/ml. As the MIC values of DR-TB isolates used for phase II ranged between 0.25 μg/ml and 1 μg/ml, a CC of 1 μg/ml was proposed. Validation of the CC in phase III showed that probably susceptible and probably resistant Rv0678 mutants overlapped at 1 μg/ml. We therefore recommend a CC of 1 μg/ml, with additional testing at 0.5 μg/ml to define an intermediate category. This was the first comprehensive study to establish a CC for routine phenotypic DST of CFZ using the MGIT960 system to guide therapeutic decisions. </sec>.

International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

Role and value of whole genome sequencing in studying tuberculosis transmission

BACKGROUND

Tuberculosis (TB) remains a serious public health threat worldwide. Theoretically ultimate resolution of whole genome sequencing (WGS) for Mycobacterium tuberculosis complex (MTBC) strain classification makes this technology very attractive for epidemiological investigations.

OBJECTIVES

To summarize the evidence available in peer-reviewed publications on the role and place of WGS in detection of TB transmission.

SOURCES

A total of 69 peer-reviewed publications identified in Pubmed database.

CONTENT

Evidence from >30 publications suggests that a cut-off value of fewer than six single nucleotide polymorphisms between strains efficiently excludes cases that are not the result of recent transmission and could be used for the identification of drug-sensitive isolates involved in direct human-to-human TB transmission. Sensitivity of WGS to identify epidemiologically linked isolates is high, reaching 100% in eight studies with specificity (17%-95%) highly dependent on the settings. Drug resistance and specific phylogenetic lineages may be associated with accelerated mutation rates affecting genetic distances. WGS can be potentially used to distinguish between true relapses and re-infections but in high-incidence low-diversity settings this would require consideration of epidemiological links and minority alleles. Data from four studies looking into within-host diversity highlight a need for developing criteria for acceptance or rejection of WGS relatedness results depending on the proportion of minority alleles.

IMPLICATIONS

WGS will potentially allow for more targeted public health actions preventing unnecessary investigations of false clusters. Consensus on standardization of raw data quality control processing criteria, analytical pipelines and reporting language is yet to be reached.

Perspectives for personalized therapy for patients with multidrug-resistant tuberculosis

According to the World Health Organization (WHO), tuberculosis is the leading cause of death attributed to a single microbial pathogen worldwide. In addition to the large number of patients affected by tuberculosis, the emergence of Mycobacterium tuberculosis drug-resistance is complicating tuberculosis control in many high-burden countries. During the past 5 years, the global number of patients identified with multidrug-resistant tuberculosis (MDR-TB), defined as bacillary resistance at least against rifampicin and isoniazid, the two most active drugs in a treatment regimen, has increased by more than 20% annually. Today we experience a historical peak in the number of patients affected by MDR-TB. The management of MDR-TB is characterized by delayed diagnosis, uncertainty of the extent of bacillary drug-resistance, imprecise standardized drug regimens and dosages, very long duration of therapy and high frequency of adverse events which all translate into a poor prognosis for many of the affected patients. Major scientific and technological advances in recent years provide new perspectives through treatment regimens tailor-made to individual needs. Where available, such personalized treatment has major implications on the treatment outcomes of patients with MDR-TB. The challenge now is to bring these adances to those patients that need them most.

In vivo virulence of Mycobacterium tuberculosis depends on a single homologue of the LytR-CpsA-Psr proteins

LytR-cpsA-Psr (LCP) domain containing proteins fulfil important functions in bacterial cell wall synthesis. In Mycobacterium tuberculosis complex (Mtbc) strains, the causative agents of tuberculosis (TB), the genes Rv3484 and Rv3267 encode for LCP proteins which are putatively involved in arabinogalactan transfer to peptidoglycan. To evaluate the significance of Rv3484 for Mtbc virulence, we generated a deletion mutant in the Mtbc strain H37Rv and studied its survival in mice upon aerosol infection. The deletion mutant failed to establish infection demonstrating that Rv3484 is essential for growth in mice. Following an initial phase of marginal replication in the lungs until day 21, the Rv3484 deletion mutant was almost eliminated by day 180 post-infectionem. Interestingly, the mutant also showed higher levels of resistance to meropenem/clavulanate and lysozyme, both targeting peptidoglycan structure. We conclude that Rv3484 is essential for Mtbc virulence in vivo where its loss of function cannot be compensated by Rv3267.

S. aureus endocarditis: Clinical aspects and experimental approaches

Infective endocarditis (IE) is a life-threatening disease, caused by septic vegetations and inflammatory foci on the surface of the endothelium and the valves. Due to its complex and often indecisive presentation the mortality rate is still about 30%. Most frequently bacterial microorganisms entering the bloodstream are the underlying origin of the intracardiac infection. While the disease was primarily restricted to younger patients suffering from rheumatic heart streptococci infections, new at risk categories for Staphylococcus (S.) aureus infections arose over the last years. Rising patient age, increasing drug resistance, intensive treatment conditions such as renal hemodialysis, immunosuppression and long term indwelling central venous catheters but also the application of modern cardiac device implants and valve prosthesis have led to emerging incidences of S. aureus IE in health care settings and community. The aetiologic change has impact on the pathophysiology of IE, the clinical presentation and the overall patient management. Despite intensive research on appropriate in vitro and in vivo models of IE and gained knowledge about the fundamental mechanisms in the formation of bacterial vegetations and extracardiac complications, improved understanding of relevant bacterial virulence factors and triggered host immune responses is required to help developing novel antipathogenic treatment strategies and pathogen specific diagnostic markers. In this review, we summarize and discuss the two main areas affected by the changing patient demographics and provide first, recent knowledge about the pathogenic strategies of S. aureus in the induction of IE, including available experimental models of IE used to study host-pathogen interactions and diagnostic and therapeutic targets. In a second focus we present diagnostic (imaging) regimens for patients with S. aureus IE according to current guidelines as well as treatment strategies and surgical recommendations.

Novel rapid PCR for the detection of Ile491Phe rpoB mutation of Mycobacterium tuberculosis, a rifampicin-resistance-conferring mutation undetected by commercial assays

OBJECTIVES

Neither the liquid medium-based Bactec MGIT, nor commercial molecular assays such as the Xpert MTB/RIF and the MTBDRplus V2.0 assays are capable of detecting up to 30% of rifampicin-resistant Mycobacterium tuberculosis strains in Swaziland because of the large proportion of the rpoB Ile491Phe mutations. In other countries, the frequency of this mutation is thought to be low.

METHODS

We designed a real-time multiplex allele-specific PCR assay to identify the rpoB Ile491Phe mutation responsible for these undetected resistant M. tuberculosis strains.

RESULTS

The technique showed 100% similarity with rpoB sequencing on a panel of 78 strains from Swaziland.

CONCLUSIONS

We propose that the detection of the rpoB Ile491Phe rpoB mutation should complement commercial assays for the diagnosis of rifampicin-resistant M. tuberculosis in routine conditions, particularly in countries where this specific mutation is frequent. The technique proposed in this paper is adapted for most reference laboratories.

Whole genome sequencing for M/XDR tuberculosis surveillance and for resistance testing

Whole genome sequencing (WGS) can help to relate Mycobacterium tuberculosis genomes to one another to assess genetic relatedness and infer the likelihood of transmission between cases. The same sequence data are now increasingly being used to predict drug resistance and susceptibility. Controlling the spread of tuberculosis and providing patients with the correct treatment are central to the World Health Organization's target to 'End TB' by 2035, for which the global prevalence of drug-resistant tuberculosis remains one of the main obstacles to success. So far, WGS has been applied largely to drug-susceptible strains for the purposes of understanding transmission, leaving a number of analytical considerations before transferring what has been learnt from drug-susceptible disease to drug-resistant tuberculosis. We discuss these potential problems here, alongside some of the challenges to characterizing the Mycobacterium tuberculosis 'resistome'-the optimal knowledge-base required for WGS-based assays to successfully direct individualized treatment regimens through the prediction of drug resistance and susceptibility in the future.

Tracing Mycobacterium tuberculosis transmission by whole genome sequencing in a high incidence setting: a retrospective population-based study in East Greenland

In East Greenland, a dramatic increase of tuberculosis (TB) incidence has been observed in recent years. Classical genotyping suggests a genetically similar Mycobacterium tuberculosis (Mtb) strain population as cause, however, precise transmission patterns are unclear. We performed whole genome sequencing (WGS) of Mtb isolates from 98% of culture-positive TB cases through 21 years (n = 182) which revealed four genomic clusters of the Euro-American lineage (mainly sub-lineage 4.8 (n = 134)). The time to the most recent common ancestor of lineage 4.8 strains was found to be 100 years. This sub-lineage further diversified in the 1970s, and massively expanded in the 1990s, a period of lowered TB awareness in Greenland. Despite the low genetic strain diversity, WGS data revealed several recent short-term transmission events in line with the increasing incidence in the region. Thus, the isolated setting and the uniformity of circulating Mtb strains indicated that the majority of East Greenlandic TB cases originated from one or few strains introduced within the last century. Thereby, the study shows the consequences of even short interruptions in TB control efforts in previously TB high incidence areas and demonstrates the potential role of WGS in detecting ongoing micro epidemics, thus guiding public health efforts in the future.

Post-invasion events after infection with Staphylococcus aureus are strongly dependent on both the host cell type and the infecting S. aureus strain

Host cell invasion is a major feature of Staphylococcus aureus and contributes to infection development. The intracellular metabolically active bacteria can induce host cell activation and death but they can also persist for long time periods. In this study a comparative analysis was performed of different well-characterized S. aureus strains in their interaction with a variety of host cell types. Staphylococcus aureus (strains 6850, USA300, LS1, SH1000, Cowan1) invasion was compared in different human cell types (epithelial and endothelial cells, keratinocytes, fibroblasts, osteoblasts). The number of intracellular bacteria was determined, cell inflammation was investigated, as well as cell death and phagosomal escape of bacteria. To explain strain-dependent differences in the secretome, a proteomic approach was used. Barrier cells took up high amounts of bacteria and were killed by aggressive strains. These strains expressed high levels of toxins, and possessed the ability to escape from phagolysosomes. Osteoblasts and keratinocytes ingested less bacteria, and were not killed, even though the primary osteoblasts were strongly activated by S. aureus. In all cell types S. aureus was able to persist. Strong differences in uptake, cytotoxicity, and inflammatory response were observed between primary cells and their corresponding cell lines, demonstrating that cell lines reflect only partially the functions and physiology of primary cells. This study provides a contribution for a better understanding of the pathomechanisms of S. aureus infections. The proteomic data provide important basic knowledge on strains commonly used in the analysis of S. aureus-host cell interaction.

Ascertaining in vivo virulence of Mycobacterium tuberculosis lineages in patients in Mbeya, Tanzania

We evaluated the relationship between the degree of immunodeficiency indicated by the number of circulating CD4+ T-cells and Mycobacterium tuberculosis lineages identified by spoligotyping and mycobacterial interspersed repetitive units-variable number of tandem repeats genotyping in human immunodeficiency virus (HIV) infected individuals with pulmonary tuberculosis from Mbeya, Tanzania. Of M. tuberculosis strains from 129 patients, respectively 55 (42.6%) and 37 (28.7%) belonged to Latin American Mediterranean and Delhi/Central-Asian lineages, while 37 (28.7%) patients were infected with other strains. There was no difference in the distribution of M. tuberculosis lineages among patients with early or advanced stages of HIV infection (P = 0.785), indicating that the virulence of strains from these lineages may not be substantially different in vivo.

Genetic diversity of Mycobacterium tuberculosis in Madang, Papua New Guinea

SETTING

Madang and surroundings, Papua New Guinea (PNG).

OBJECTIVE

To characterise the genetic diversity and drug susceptibility of Mycobacterium tuberculosis isolates collected in Madang and surroundings.

DESIGN

M. tuberculosis was isolated from sputum samples from active pulmonary tuberculosis cases. Drug resistance profiles were obtained by drug susceptibility testing. M. tuberculosis lineages were identified by single nucleotide polymorphisms and sub-typing was performed by spoligotyping. Spoligotyping and 24 locus mycobacterial interspersed repetitive units-variable number of tandem repeats were combined to identify clustered isolates.

RESULTS

The 173 M. tuberculosis isolates collected belonged predominantly to the Euro-American lineage (Lineage 4) and the East-Asian lineage (Lineage 2). Multidrug-resistant M. tuberculosis were observed in 5.2% of isolates. Lineage 2 M. tuberculosis, which includes the 'Beijing' genotype, was significantly associated with any drug resistance (OR 5.2, 95%CI 1.8-15.1). Cluster analyses showed 44% molecularly clustered isolates, suggesting transmission of M. tuberculosis in the community, including transmission of primary drug-resistant M. tuberculosis.

CONCLUSION

These data provide the first insight into the molecular characteristics of M. tuberculosis in the Madang area of PNG, and indicate substantial drug resistance with evidence of ongoing transmission.

[Tuberculosis outbreak in 13 people in Saxony-Anhalt: indications of an infection chain by spoligotyping]

BACKGROUND

In Germany the number of new tuberculosis incidents continues to decline slightly. Cases of illnesses are often diagnosed late, due to the uncharacteristic course of tuberculosis. The success in environment investigations by health authorities in finding incidents within one infection chain depends on the compliance of patients among other factors. Tuberculosis occurs especially in groups with social disadvantages. In this population segment the identification of contact persons of a patient with infectious tuberculosis presents difficulties. Moreover, identifying the source of infection is frequently not successful. For these reasons, additional infections and sicknesses are caused. The cultural pathogen proof, including type differentiation and resistance testing, continues to be the "gold standard" in tuberculosis diagnostics and is required for the examination of outbreaks. Molecular methods for fine typification of isolated bacterial strains and their subsequent comparison constitute an important tool in the infection epidemiology investigation of incident clustering.

OBJECTIVE AND METHOD

The objective of this work is the description of a tuberculosis infection chain in Saxony-Anhalt, which was discovered by means of a molecular biological method. The conservative method represents the environment investigations for the expedient selection of contact persons. The investigations always take 2 directions in the process. On the one hand, it is searched for the still unknown source of infection. On the other hand, persons are to be identified, who have been infected before the diagnosis became known. The diagnostics for contact persons includes besides the lung X-ray checkup exam, the Mendel Mantoux tuberculin skin test (THT), sputum tests and the Interferon Gamma (INF-γ) tests (IGRA). In described case, the molecular biological method of spoliogotyping was employed as additional instrument. Therein, fingerprint maps of the patients' tuberculosis strings were created and compared. Infection chains resulting from the environment investigations were thereby secured.

RESULTS

We report on a tuberculosis outbreak in a district of the state of Saxony-Anhalt, which occurred in the time from June 2007 to May 2010. As result of the environment investigations, an infection chain of 13 ill patients (77% ♂, 23% ♀) was identified. In 11 cases the correlation of the infection chain was proven by spoligotyping (9 ♂, 2 ♀). 2 cases (1 ♂, 1 ♀) without verification of the pathogen cannot be attributed on basis of the epidemiological correlations.

Motoneuron-specific NR3B gene: no association with ALS and evidence for a common null allele

OBJECTIVE

The GRIN3B gene encodes NR3B, a motoneuron-specific member of the NMDA type of ionotropic glutamate receptors. NR3B reduces the Ca(2+)-permeability as well as the overall current of the receptor response and may thereby protect motoneurons against glutamate-mediated excitotoxicity. We tested whether genetic dysfunction of GRIN3B is implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS).

METHODS

We searched for mutations in the GRIN3B coding region (3.1 kb) in 117 individuals with familial ALS and in 46 individuals with sporadic ALS. We genotyped the newly identified GRIN3B null allele and four "tag single nucleotide polymorphisms (SNPs)" at the GRIN3B locus in 342 individuals with sporadic ALS and in 374 matched controls. The GRIN3B null allele frequency was determined in 2,128 individuals from a worldwide panel of 42 populations. We furthermore compared the GRIN3B coding sequence in primates (human-macaque) and rodents (rat-mouse) to evaluate the molecular evolution of GRIN3B.

RESULTS

Thirty-two SNPs, including 16 previously unreported SNPs, one 27-bp deletion, a polymorphic CAG repeat, and a 4-bp insertion (insCGTT), were identified. Mutational and case-control studies did not reveal variants that cause or modify disease in ALS. Intriguing is an insCGTT variant that truncates the protein at its amino terminus and results in a GRIN3B null allele. We demonstrated a global distribution of the null allele with allele frequencies ranging between 0 and 0.38, and we delineated a null allele specific haplotype of 9.89 kb. Comparative genomic analysis across four taxa demonstrated accelerated evolution of NR3B in primates.

CONCLUSIONS

Our study supports the conclusions that 1) GRIN3B does not seem to be associated with familial or sporadic ALS, 2) the GRIN3B null allele is a common polymorphism, 3) the GRIN3B null allele has arisen once and early in human evolution, and 4) the GRIN3B gene belongs to a group of nervous system-related genes that have been subjected to faster evolution during evolution.

Patient information on cognitive symptoms in multiple sclerosis - acceptability in relation to disease duration

OBJECTIVE

Recently, regular cognitive screening assessments have been advised in multiple sclerosis (MS). No studies have been carried out yet on the acceptability of information on cognitive deficits among MS patients.

MATERIALS AND METHODS

Translation of an information booklet developed by a working group of European MS Rehabilitation Centers. Distribution of the booklet among 133 MS patients of two rehabilitation units and one outpatient clinic together with a one-page questionnaire.

RESULTS

The booklet was highly understandable and rated to give moderate new information. Overall, the brochure was perceived as encouraging but significantly less so (P = 0.014) in recently diagnosed patients. Patients with subjectively perceived deficits considered the brochure to be significantly more relevant (P = 0.002).

CONCLUSION

Information on cognitive deficits does not increase fears even in recently diagnosed MS patients. Patients with perceived deficits found the information more relevant than others and also less familiar. Thus, it seems appropriate to offer information about cognitive impairments to MS patients.

No associations of human pulmonary tuberculosis with Sp110 variants

BACKGROUND

After a recent report on the role of the Ipr1 gene in mediating innate immunity in a mouse model of Mycobacterium tuberculosis infection, the human Ipr1 homologue, Sp110, was considered a promising candidate for an association study in human tuberculosis.

METHODS

In a sample of >1000 sputum positive, HIV negative West African patients with pulmonary tuberculosis and >1000 exposed, apparently healthy controls, we have genotyped 21 Sp110 gene variants that were either available from public databases, including HapMap data, or identified by DNA re-sequencing.

RESULTS

No significant differences in the frequencies of any of the 21 variants were observed between patients and controls. This applied also for HapMap tagging variants and the corresponding haplotypes, when including sliding window analyses with three adjacent variants, and when stratifying controls for positivity and negativity according to the results of intradermal tuberculin (purified protein derivative, PPD) skin tests. DNA re-sequencing revealed 13 novel Sp110 variants in the 5'-UTR, exons, and adjacent intronic regions.

CONCLUSIONS

Based on the results obtained in this case-control study, the hypothesis that Sp110 variants and haplotypes might be associated with distinct phenotypes of human M tuberculosis infection is doubtful.

Landouzy septicemia (sepsis tuberculosa acutissima) due to Mycobacterium microti in an immunocompetent man

Even in developed countries, tuberculosis still contributes significantly to morbidity and mortality. The most frequent causative agent is Mycobacterium tuberculosis, while infections due to other mycobacterial species are usually associated with immunocompromised patients. In the following, we describe the case of a previously healthy man who underwent laparotomy for suspected adrenal carcinoma. Peritoneal "cancerous nodules" turned out to be tuberculous granulomas. After surgery the patient developed a protracted septic shock and died 6 days after surgery. Isolation and identification of the causative agent yielded Mycobacterium microti, an uncommon species of the M. tuberculosis complex. No other pathogen could be isolated during the clinical course, which finally led to the diagnosis of Landouzy septicemia (sepsis tuberculosa acutissima).

Avoiding the effect of BCG vaccination in detecting Mycobacterium tuberculosis infection with a blood test

Bacille Calmette-Guérin (BCG) vaccination can confound tuberculin skin test (TST) reactions in the diagnosis of latent tuberculosis infection (LTBI). The TST was compared with a Mycobacterium tuberculosis (MTB)-specific enzyme-linked immunospot (ELISPOT) assay during an outbreak of MTB infection at a police academy in Germany. Participants were grouped according to their risk of LTBI in close (n = 36) or occasional (n = 333) contacts to the index case. For the TST, the positive response rate was 53% (19 out of 36) among close and 16% (52 out of 333) among occasional contacts. In total, 56 TST-positive contacts (56 out of 71 = 78.9%) and 27 TST-negative controls (27 out of 298 = 9.1%) underwent ELISPOT testing. The odds ratio (OR) of a positive test result across the two groups was 29.2 (95% confidence interval (CI) 3.5-245.0) for the ELISPOT and 19.7 (95% CI 2.0-190.2) for the TST with a 5 mm cut-off. Of 369 contacts, 158 (42.8%) had previously received BCG vaccination. The overall agreement between the TST and the ELISPOT was low, and positive TST reactions were confounded by BCG vaccination (OR 4.8 (95% CI 1.3-18.0)). In contrast, use of a 10-mm induration cut-off for the TST among occasional contacts showed strong agreement between TST and ELISPOT in nonvaccinated persons. In bacille Calmette-Guérin-vaccinated individuals, the Mycobacterium tuberculosis-specific enzyme-linked immunospot assay is a better indicator for the risk of latent tuberculosis infection than the tuberculin skin test.

Rifampicin and isoniazid resistance mutations in Mycobacterium tuberculosis strains isolated from patients in Kazakhstan

OBJECTIVE

To analyse possible associations of specific mutations conferring rifampicin (RMP) and isoniazid (INH) resistance with Beijing and non Beijing genotype strains of Mycobacterium tuberculosis from Kazakhstan.

METHOD

Genotypic analysis of 92 multidrug-resistant (MDR), 50 INH but not RMP-resistant (INHr/RMPs) and 10 fully susceptible strains of M. tuberculosis from Kazakhstan was performed. In the MDR group, 59 strains (64.1%), and within the INHr/RMPs group, 32 strains (64.0%) were classified as Beijing genotype.

RESULTS

Analysis of the rpoB gene of the MDR strains revealed 10 different mutations in five codons, with rpoB codons 531 (65.2%), 526 (23.9%) and 516 (7.6%) most frequently affected. A significantly higher proportion of the rpoB S531L mutation was found among Beijing genotype strains compared with non Beijing strains (71.2% vs. 46.2%, P = 0.027). All 92 MDR isolates (100%), irrespective of their genotype, carried a mutation in codon 315 of the katG gene (S315T). However, in the INHr/RMPS control group, the S315T mutation was significantly more prevalent in the Beijing than in the non Beijing group (96.9% vs. 71.4%, P = 0.012).

CONCLUSION

The high similarity of mutations supports the assumption that transmission of resistant strains is a major reason for the emergence of drug resistance in this region.

The Beijing genotype is a major cause of drug-resistant tuberculosis in Kazakhstan

SETTING

Nine Kazakhstan oblasts, 2001.

OBJECTIVE

To analyse the genetic relationship of drug-resistant Mycobacterium tuberculosis strains from Kazakhstan and to determine the frequency of the Beijing genotype.

DESIGN

All drug-resistant smear-positive cases identified in nine oblasts during the 2001 nationwide drug resistance survey were analysed by IS6110 fingerprinting and spoligotyping. Isolates were obtained from 150 patients (64 new and 86 retreated cases).

RESULTS

Eight cases (5.3%) of dual infection were identified. Of the remaining 142 strains, 91 (64.1%) were grouped in 18 clusters, indicating a high rate of recent transmission of resistant tuberculosis (TB). This was further confirmed by the origin of the patients as well as by the similar drug resistance patterns of the clustered strains. Accordingly, more than one third of all clustered strains were new cases. About 70% of the resistant strains belonged to the Beijing genotype, compared to only 37.5% in a control group of 40 susceptible isolates.

CONCLUSIONS

Transmission of drug-resistant strains seems to contribute to the spread of resistant TB in this high incidence region. The Beijing genotype should be seen as a major cause of drug-resistant TB in Kazakhstan and was found to be associated with drug resistance.

The species Mycobacterium africanum in the light of new molecular markers

The findings of recent studies addressing the molecular characteristics of Mycobacterium tuberculosis complex isolates have initiated a discussion on the classification of M. africanum, especially of those isolates originating from East Africa (cluster F, subtype II) and displaying phenotypic and biochemical characteristics more similar to those of M. tuberculosis. To further address this question, we analyzed a representative collection of 63 M. tuberculosis complex strains comprising 30 M. africanum subtype I strains, 20 M. africanum subtype II strains, 10 randomly chosen M. tuberculosis isolates, and type strains of M. tuberculosis, M. bovis, and M. africanum for the following biochemical and molecular characteristics: single-nucleotide polymorphisms (SNPs) in gyrB and narGHJI and the presence or absence of RD1, RD9, and RD12. For all molecular markers analyzed, subtype II strains were identical to the M. tuberculosis strains tested. In contrast, the subtype I strains as well as the M. africanum type strain showed unique combinations of SNPs in gyrB and genomic deletions (the absence of RD9 and the presence of RD12), which proves their independence from M. tuberculosis and M. bovis. Accordingly, all subtype I strains displayed main biochemical characteristics included in the original species description of M. africanum. We conclude that the isolates from West Africa were proved to be M. africanum with respect to the phenotypic and genetic markers analyzed, while the isolates from East Africa must be regarded as phenotypic variants of M. tuberculosis (genotype Uganda). We propose the addition of the molecular characteristics defined here to the species description of M. africanum, which will allow clearer species differentiation in the future.

The Beijing genotype is emerging among multidrug-resistant Mycobacterium tuberculosis strains from Germany

SETTING

Germany, 1995 to 2001.

OBJECTIVE

To determine the genetic relationship of 451 multidrug-resistant (MDR) Mycobacterium tuberculosis strains from Germany and to identify strains of the Beijing genotype.

DESIGN

All strains were analysed using IS6110 fingerprinting and a cluster analysis was performed. Clustering of isolates was used as a measure for recent transmission.

RESULTS

Two hundred and fourteen of 433 strains (49.4%) with more than four IS6110 copies formed 46 fingerprint clusters comprising two to 32 patients. Transmission links based on classical epidemiological data could be established for 39 cases (18.2%) and in 14 clusters (30.4%), and included three cases of exogenous reinfection with MDR strains. One hundred and seventy-five strains (38.8%) were of the Beijing genotype with an increasing annual proportion from 19.2% in 1995 to 58.3% in 2001. About 70% of these patients had an indication of foreign birth, mainly the former Soviet Union.

CONCLUSION

Transmission of MDR strains seems to be contributing to the spread of MDR-TB in Germany, and exogenous reinfection with MDR strains must be considered as a possible cause of treatment failure. A high proportion of these MDR strains is probably carried over from the former Soviet Union, and strains of the Beijing genotype represent an increasing cause of MDR-TB in Germany.

Familial ALS in Germany: origin of the R115G SOD1 mutation by a founder effect

Mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1) account for approximately 20% of patients with familial amyotrophic lateral sclerosis (FALS). In this study, sequence analysis of exons 1-5 of SOD1 in a large German cohort with FALS was performed. Among 75 affected patients, who were not obviously related probands with a positive family history, nine had missense mutations in SOD1. Four of the nine probands carry the same R115G mutation in exon 4 of the SOD1 gene. Genotyping with markers from the SOD1 locus revealed a common haplotype and shared allelic characteristics in these patients. These findings suggest that the R115G mutation in the German population originates from a common founder.

Ongoing outbreak of tuberculosis in a low-incidence community: a molecular-epidemiological evaluation

SETTING

Federal State of Hamburg, Germany, 1997-2002.

OBJECTIVE

To identify the pathways of tuberculosis (TB) transmission and to evaluate possible risk factors for recent transmission in Hamburg.

DESIGN

A prospective, molecular-epidemiological study was performed. Conventional contact tracing and an indepth epidemiological analysis were conducted.

RESULTS

A predominant cluster of Mycobacterium tuberculosis strains was identified by IS6110 DNA fingerprinting of 828 TB cases notified during the study period. The cluster expanded from seven cases in 1997 to 38 in June 2002. A single source case could not be identified. Transmission links were confirmed in 20 cases. Twenty-five patients were regular customers at a bar close to the red-light district. Seven patients, including one regular customer in the bar, were staying at a nearby hostel for homeless men, and four were living in a far-away hostel for alcoholic men. Of the 421 close contact persons investigated, 169 (40.1%) had positive tuberculin skin tests, and eight became ill (1.9%). Twelve of 20 cases with confirmed recent transmission could only be determined a posteriori by fingerprinting.

CONCLUSIONS

An ongoing outbreak at a local bar indicates chronic alcoholism as a high-risk factor for the dissemination of TB in a large metropolitan area. The fact that conventional contact tracing is insufficient for the detection of chains of transmission in this milieu indicates the need for an improved, location-based approach, e.g., the implementation of an outreach strategy.

[Spread of a drug-resistant strain of mycobacterium tuberculosis among homeless people in a German city]

BACKGROUND

Cases of active pulmonary tuberculosis are much more common among homeless people because of their personal risk factors than in the average population; it is assumed that there are about 500 000 homeless people in the Federal Republic of Germany. Several sputum samples were sent from the tuberculosis advice center of the public health office in Hannover to the governmental institute of public health services of Lower Saxony in fall 1996 in order to carry out laboratory tests for mycobacteria. The isolates found revealed an unusual pattern of drug resistance to streptomycin and rifampin.

METHODS

The sputum samples were tested according to the usual standard test procedures as described in DIN 58 943-3 (DIN standard of the German Institute for Standardization) and in MiQ 5/1998 (Quality standards in microbiology-infectiologic diagnostics issued by the German Society for Hygiene and Microbiology [DGHM]. DNA-fingerprinting was carried out by the IS 6110-RFLP-technique.

PATIENTS

In Hannover a total of 12 patients with an active pulmonary tuberculosis, whose M. tuberculosis-strains showed resistance to streptomycin and rifampin, were investigated. 9 of the 12 patients were homeless and lodged in a homeless shelter of the city; in one case a healthcare worker acquired a tuberculosis infection while caring for these patients.

RESULTS

The identity of the 12 isolated mycobacteria strains could be proved by IS 6110-fingerprinting. The result clearly indicates the existence of a tuberculosis cluster among the homeless people in a German city. The treatment of the homeless persons proved to be difficult because of the lack of compliance; in 4 cases compulsory isolation with therapy in a closed clinic was unavoidable and beforehand 2 of the patients even had to be tracked down by the police.

CONCLUSIONS

The German law on the prevention of infectious diseases offers some new possibilities to the public health offices concerning the control and prevention of tuberculosis among homeless persons. For example the public health offices are now allowed to run a "preventive visiting services" prevention and to practice ambulant therapies; the payment of the costs for poor patients is prescribed, too. These possibilities should be used in an extended way, as the efforts to control the spread to tuberculosis among homeless people need to be intensified.

Prospective molecular epidemiological study on transmission of pulmonary Tuberculosis and Migration (MuT study) -- an interim report

INTRODUCTION

In Western Europe prevalence and incidence of tuberculosis in the indigenous population is declining and TB in migrants from high prevalence countries is becoming a major issue of TB control. Resulting changes in transmission patterns need to be investigated to adapt control strategies. The MuT (Migration and Tuberculosis) study a co-operation among federal and local public health services (ODG), the National Surveillance Center (RKI) and the University has been established in Baden-Wuerttemberg to address these issues.

OBJECTIVES

The goal of this ongoing study is to determine the transmission dynamics of TB in Baden-Wuerttemberg. Here, we present the first set of data on TB cases and their contacts and discuss strategies to overcome arising difficulties.

METHODS

Prospective data collection of culture positive pulmonary tuberculosis cases and their contacts. Analysis of (1) routine data, (2) spatial data, (3) social interaction data, (4) molecular typing data, and (5) observational data of the implementation phase.

RESULTS

The study demonstrates the capability of the study consortium to identify clusters. It provides valuable insights into current case detection and case management procedures and shows ways to improve. A set of factors has been identified that (a) facilitate and (b) discourage study participation.

CONCLUSION

Collaboration among federal and local public health services (OGD), National Surveillance Center (RKI) and the University is a promising approach to investigate and improve TB control. This model has potentials for other infectious disease control.