Uptake of the lateral flow urine LAM test in Europe and Central Asia

INTRODUCTION:

Since 2015 (updated in 2019), the WHO has recommended to include the commercial lateral flow urine lipoarabinomannan TB test (LF-LAM), AlereLAM, in the diagnostic toolkit for severely ill people living with HIV.

METHODS:

To assess the current use and barriers to the implementation of the test, we conducted an electronic survey among national focal points and managers of TB and HIV programmes in the 53 Member States of the WHO European Region and a European network of clinicians working in TB and HIV medicine.

RESULTS:

In all, 45 individual responses (37 countries) were received from programme managers and focal points and 17 responses (14 countries) from clinicians. Only eight countries reported adopting LF-LAM policies, with only four currently using the AlereLAM (Armenia, Belarus, Ukraine and Uzbekistan). The most commonly reported barriers to implementing the test were the small number of eligible patients (with HIV-TB co-infections), the test not being included in the TB or HIV programme’s mandate and lack of budget allocation.

CONCLUSION:

Consistent with findings from high TB burden countries in Africa and Asia, the survey demonstrated that uptake of AlereLAM is almost non-existent. Addressing the identified barriers and the intrinsic limitations of the test could help to increase the use of the test.

Decreasing trend of drug-resistant TB in Italy

BACKGROUND: TB caused by rifampicin-resistant (RR) and multidrug-resistant (MDR) Mycobacterium tuberculosis strains is a major concern to TB control globally. However, in the European Union, MDR-TB notifications among all bacteriologically confirmed TB cases with available drug susceptibility testing (DST) results decreased over the last years.METHODS: We conducted a retrospective analysis on DST results reported from 2011 to 2020 by 46 laboratories in 19 out of 20 regions in Italy in order to evaluate resistance trends to first- and second-line drugs in MDR/RR-TB strains isolated from Italian-born persons (IBPs) and foreign-born persons (FBPs).RESULTS: Of 23,972 M. tuberculosis strains examined (15,519 from FBPs and 8,453 from IBPs), MDR-TB decreased from 3.2% in 2011 to 2.2% in 2020. High MDR/RR-TB rates occurred mostly in FBPs from former Soviet Union countries. In 2017, a MDR/RR-TB increase was detected in FBPs from sub-Saharan Africa. MDR-TB strains showed consistent increase in resistance to pyrazinamide (PZA), slight increase in resistance to fluoroquinolones and a decrease in resistance to other drugs.CONCLUSION: While MDR/RR-TB cases slightly decreased, a worrisome increase of resistance to PZA and fluoroquinolones among MDR/RR-TB patients was seen. This implies that a fast and efficient diagnosis aligned with therapy is crucial for TB control.

Clinical standards for the dosing and management of TB drugs

BACKGROUND: Optimal drug dosing is important to ensure adequate response to treatment, prevent development of drug resistance and reduce drug toxicity. The aim of these clinical standards is to provide guidance on 'best practice´ for dosing and management of TB drugs.METHODS: A panel of 57 global experts in the fields of microbiology, pharmacology and TB care were identified; 51 participated in a Delphi process. A 5-point Likert scale was used to score draft standards. The final document represents the broad consensus and was approved by all participants.RESULTS: Six clinical standards were defined: Standard 1, defining the most appropriate initial dose for TB treatment; Standard 2, identifying patients who may be at risk of sub-optimal drug exposure; Standard 3, identifying patients at risk of developing drug-related toxicity and how best to manage this risk; Standard 4, identifying patients who can benefit from therapeutic drug monitoring (TDM); Standard 5, highlighting education and counselling that should be provided to people initiating TB treatment; and Standard 6, providing essential education for healthcare professionals. In addition, consensus research priorities were identified.CONCLUSION: This is the first consensus-based Clinical Standards for the dosing and management of TB drugs to guide clinicians and programme managers in planning and implementation of locally appropriate measures for optimal person-centred treatment to improve patient care.

Therapeutic strategies and outcomes of MDR and pre-XDR-TB in Italy: a nationwide study

BACKGROUND: Treatment outcomes in multidrug-resistant TB (MDR-TB) patients are suboptimal in several low-incidence countries.METHODS: The primary outcome measure was the proportion of successfully treated patients in Italy during an 18-year period. Secondary outcomes were treatment outcomes in certain drug-containing regimens and the possibility for the WHO shorter MDR-TB regimen.RESULTS: In the 191 patients included (median age at admission: 33 years; 67.5% male, following drug-resistance patterns were found: MDR-TB in 68.6%, pre-extensively drug-resistant TB (pre-XDR-TB) in 30.4% and XDR-TB in 1.1% patients. The most frequently prescribed drugs were fluoroquinolones in 84.6% cases, amikacin in 48.7%, linezolid in 34.6% and meropenem/clavulanic acid in 29.5%. The median duration of treatment was 18 months. Treatment success was achieved in 71.2% patients, of whom, 44% were cured and 27.2% completed treatment. Treatment success rates did not statistically differ between the MDR- (68.8%) and pre-XDR-TB (77.6%) groups (P = 0.26). Treatment success rates had large variability between North and South of Italy (81.3% vs. 53.3%). Only 22.5% of the cases would have been eligible for shorter MDR-TB regimensCONCLUSION: Our study highlights variability in treatment outcomes in MDR- and pre-XDR-TB patients. Study findings confirmed the potential utility of linezolid and, for patients with limited oral options, meropenem/clavulanic acid and amikacin.

First molecular-based anti-TB drug resistance survey in Eritrea

BACKGROUND: In the absence of reliable data on drug-resistant TB in Eritrea, a national survey was conducted in 2018 using molecular-based methods, bypassing the need for culture.METHODS: A cross-sectional study was conducted in all 77 TB microscopy centres in the country. All 629 newly registered sputum smear-positive pulmonary TB patients were enrolled over 12 months. Sputum samples were tested using the Xpert^® MTB/RIF assay and targeted next-generation sequencing (Deeplex Myc-TB) to identify resistance and explore the phylogenetics of Mycobacterium tuberculosis complex strains.RESULTS: Drug resistance profiles were obtained for 555 patients (502 new, 53 previously treated). The prevalence of rifampicin-resistant TB (RR-TB) was respectively 2.0% and 7.6% among new and previously treated cases. All RR-TB isolates that were susceptible to isoniazid displayed a phylogenetic marker conferring capreomycin resistance, confirming circulation of a previously described resistant TB sub-lineage in the Horn of Africa. Only one case of fluoroquinolone resistance was detected.CONCLUSION: The prevalence of rifampicin resistance among TB patients is encouragingly low. The scarcity of fluoroquinolone resistance bodes well for the success of the recommended all-oral treatment regimen. Surveillance based on molecular approaches enables a reliable estimation of the burden of resistance and can be used to guide appropriate treatment and care.

Latent tuberculous infection among foreign-born individuals applying to shelters in the metropolitan area of Milan

SETTING

Screening for latent tuberculous infection (LTBI) of groups at high risk of active tuberculosis (TB) is a key component of the End TB Strategy.

OBJECTIVE

To conduct a retrospective descriptive analysis of LTBI rates among foreign-born individuals applying to shelters in the metropolitan area of Milan, Italy.

DESIGN

All foreign-born individuals registering for accommodation centres in the city of Milan from November 2009 to April 2017 were screened for active TB and LTBI. Individuals aged <36 years with a tuberculin skin test (TST) induration of >10 mm were offered confirmatory testing with QuantiFERON®-TB Gold In-Tube (QFT-GIT).

RESULTS

Of the 2666 TST-positive migrants aged <36 years who underwent LTBI confirmation testing, 1322 (49.6%) tested negative, 1339 (50.2%) were positive and five (0.2%) had indeterminate results. In the multivariate analysis, TB incidence in the country of origin and age were significantly associated with QFT-GIT positivity. Although estimated TB incidence in Eritrea, Morocco and Romania was 100/100 000 person-years (py), the probability of being QFT-GIT-positive in individuals from these countries were not statistically significantly different from individuals from countries with TB incidence > 250/100 000 person-years.

CONCLUSION

Our data showed a high proportion of LTBI among individuals coming from intermediate TB burden countries.

Fluoroquinolone heteroresistance in Mycobacterium tuberculosis: detection by genotypic and phenotypic assays in experimentally mixed populations

Heteroresistance - the simultaneous presence of drug-susceptible and -resistant organisms - is common in Mycobacterium tuberculosis. In this study, we aimed to determine the limit of detection (LOD) of genotypic assays to detect gatifloxacin-resistant mutants in experimentally mixed populations. A fluoroquinolone-susceptible M. tuberculosis mother strain (S) and its in vitro selected resistant daughter strain harbouring the D94G mutation in gyrA (R) were mixed at different ratio’s. Minimum inhibitory concentrations (MICs) against gatifloxacin were determined, while PCR-based techniques included: line probe assays (Genotype MTBDRsl and GenoScholar-FQ + KM TB II), Sanger sequencing and targeted deep sequencing. Droplet digital PCR was used as molecular reference method. A breakpoint concentration of 0.25 mg/L allows the phenotypic detection of ≥1% resistant bacilli, whereas at 0.5 mg/L ≥ 5% resistant bacilli are detected. Line probe assays detected ≥5% mutants. Sanger sequencing required the presence of around 15% mutant bacilli to be detected as (hetero) resistant, while targeted deep sequencing detected ≤1% mutants. Deep sequencing and phenotypic testing are the most sensitive methods for detection of fluoroquinolone-resistant minority populations, followed by line probe assays (provided that the mutation is confirmed by a mutation band), while Sanger sequencing proved to be the least sensitive method.

Is sequencing better than phenotypic tests for the detection of pyrazinamide resistance?

SETTING

Phenotypic tests used to detect pyrazinamide (PZA) resistance are slow and have a high rate of false resistance.

OBJECTIVE

To evaluate the accuracy of pncA sequencing for the detection of PZA resistance in Mycobacterium tuberculosis strains isolated in Tunisia.

DESIGN

A total of 82 isolates, 41 resistant and 41 susceptible to PZA on BACTEC™ MGIT™ 960, were sequenced for pncA. Whole genome sequencing was performed for strains that were phenotypically resistant and had wild-type pncA in addition to MGIT retesting with a modified protocol.

RESULTS

Twenty-three strains resistant to PZA with negative pyrazinamidase (PZase) activity harboured a mutation in the promoter or coding region of pncA. However, 18 strains resistant to PZA did not present any mutation. Repeat MGIT 960 showed that 16 of 18 M. tuberculosis isolates were falsely resistant to PZA. Compared with MGIT, PZase activity assay and pncA sequencing both presented a sensitivity of 92.0% (95%CI 73.9-99.0) and a specificity of respectively 96.5% (positive predictive value [PPV] 92.0%, negative predictive value [NPV] 96.5%) and 100.0% (PPV 100.0%, NPV 96.6%).

CONCLUSION

The standard MGIT assay showed a high rate of false resistance to PZA, and the PZase activity assay is slow. pncA sequencing could therefore represent a rapid, accurate, alternative test to detect PZA resistance.

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.

Alarming levels of multidrug-resistant tuberculosis in Ukraine: results from the first national survey

SETTING

The true prevalence of multidrug-resistant tuberculosis (MDR-TB) in Ukraine is not known. Available data are a decade old and limited to only one province.

OBJECTIVE

To determine the prevalence of MDR-TB among new and previously treated TB cases in Ukraine and explore the risk factors associated with drug resistance.

METHODS

A total of 1550 sputum smear-positive pulmonary TB patients were recruited from 40 clusters throughout Ukraine. Sputum specimens were examined using culture, drug susceptibility testing and pncA gene sequencing.

RESULTS

The proportion of MDR-TB among new and previously treated TB cases was respectively 24.1% (95%CI 20.7-27.6) and 58.1% (95%CI 52.1-64.1). More than one third (38.0%) of MDR-TB or rifampicin (RMP) resistant cases showed resistance to either a fluoroquinolone (FQ) or a second-line injectable agent or both. Resistance to pyrazinamide and FQs was low in patients with RMP-susceptible TB. Among new TB cases, the odds of MDR-TB were higher among patients who were younger, female and living in south-eastern provinces, as well as among human immunodeficiency virus-positive patients who belonged to a low socio-economic group.

CONCLUSIONS

Our study showed that the burden of MDR-TB in Ukraine was much greater than previously assumed. Urgent actions are needed to prevent further spread of drug-resistant TB in Ukraine.

MOLECULAR TYPING OF MYCOBACTERIUM KANSASII — A GLOBAL PERSPECTIVE

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Treatment outcome with a short multidrug-resistant tuberculosis regimen in nine African countries

SETTING

Nine countries in West and Central Africa.

OBJECTIVE

To assess outcomes and adverse drug events of a standardised 9-month treatment regimen for multidrug-resistant tuberculosis (MDR-TB) among patients never previously treated with second-line drugs.

DESIGN

Prospective observational study of MDR-TB patients treated with a standardised 9-month regimen including moxifloxacin, clofazimine, ethambutol (EMB) and pyrazinamide (PZA) throughout, supplemented by kanamycin, prothionamide and high-dose isoniazid during an intensive phase of a minimum of 4 to a maximum of 6 months.

RESULTS

Among the 1006 MDR-TB patients included in the study, 200 (19.9%) were infected with the human immunodeficiency virus (HIV). Outcomes were as follows: 728 (72.4%) cured, 93 (9.2%) treatment completed (81.6% success), 59 (5.9%) failures, 78 (7.8%) deaths, 48 (4.8%) lost to follow-up. The proportion of deaths was much higher among HIV-infected patients (19.0% vs. 5.0%). Treatment success did not differ by HIV status among survivors. Fluoroquinolone resistance was the main cause of failure, while resistance to PZA, ethionamide or EMB did not influence bacteriological outcome. The most important adverse drug event was hearing impairment (11.4% severe deterioration after 4 months).

CONCLUSIONS

The study results support the use of the short regimen recently recommended by the World Health Organization. Its high level of success even among HIV-positive patients promises substantial improvements in TB control.

Evaluation of a novel line probe assay to detect resistance to pyrazinamide, a key drug used for tuberculosis treatment

OBJECTIVES

The development of rapid molecular diagnostic assays for pyrazinamide (PZA) resistance is considered technically challenging as mutations are highly diverse, scattered along the full length of the pncA gene and not all are associated with PZA resistance. We evaluated the performance of the novel Genoscholar PZA-TB II line probe assay (PZA-LPA2; NIPRO Corporation, Japan).

METHODS

To evaluate the applicability of the PZA-LPA2 in clinical settings, we compared the performance of the PZA-LPA2 to a composite reference standard pncA Sanger and Illumina sequencing plus phenotypic susceptibility testing on a panel of 87 Mycobacterium tuberculosis isolates from World Health Organization (WHO) drug resistance surveys, harbouring mutations previously classified as associated or not associated with resistance according to data from peer-reviewed literature. In addition, the PZA-LPA2 was challenged against a selection of isolates with lineage-specific and non-resistance-associated mutations, for which the frequency among clinical isolates is unknown, and tested directly on 59 sputum extracts.

RESULTS

For the survey isolates, the PZA-LPA2 reached an overall agreement with the composite reference of 97.6% (80/82) or 94.3% (82/87) excluding or including heteroresistance, respectively. The PZA-LPA2 failed on 8.5% (5/59) of clinical samples; among valid results, 100% (14/14) sensitivity and 100% (7/7) specificity was reached relative to pncA Sanger sequencing.

CONCLUSIONS

The PZA-LPA2 represents a valid and rapid alternative for indirect PZA susceptibility testing. Preliminary findings on clinical samples show promise for direct testing. Further studies are needed to assess the clinical risk of missing heteroresistance and falsely detecting lineage-specific, silent and nonassociated mutations.

Best approaches to drug-resistance surveillance at the country level

In 2014, the World Health Organization (WHO) recommendation to include the endorsed rapid molecular technologies (Xpert MTB/RIF, line probe assays) into surveillance systems and surveys allowed the testing of more tuberculosis (TB) patients for drug resistance at country level than ever before. The whole genome sequencing (WGS) approach is emerging as a more powerful tool for epidemiological and drug-resistant routine surveillances, promising a rapid and simultaneous screening of all the clinically-relevant mutations for the determination of resistance to the first-, second-line, and new anti-TB drugs. In addition, WGS can support the conventional contact tracing for epidemiological studies with high discriminatory power by tracking the circulating strains and their relatedness. These features make WGS, moreso than the conventional molecular tools, an ideal tool to monitor transmission and drug resistance trends in countries, providing deep and wide information in a standardized way. WGS technologies have already been adopted in many supranational and reference laboratories at the centralized level, and several research groups are working to reduce the complexity and costs of these platforms, from sample preparation to the downstream analysis and interpretation of sequencing reads, with the final aim to expand the use of WGS to all laboratory levels. The landscape of the platforms available for next-generation sequencing (NGS) is rapidly enriching. It includes high-throughput instruments that can be used for centralized surveillance studies on a large scale, and "benchtop" sequencers that conversely can reach more peripheral settings for rapid and non-extensive surveys. Traditionally, WGS is performed on genomic DNA samples extracted from clinical isolates to ensure the required high DNA quality and quantity for the following library preparation and sequencing reaction steps. Nevertheless, the researchers are trying to apply the WGS to early primary cultures and in particular directly to sputum samples, including specific procedures to remove non-mycobacterial genetic material and to enrich the Mycobacterium tuberculosis (MTB) genome. The targeted NGS approach that takes advantage of the amplification of selected regions of the MTB genome for genotyping and drug resistance determination could represent the most effective method to avoid the need of culturing MTB prior to sequencing, also enabling the implementation of NGS for surveillance purposes in resource-limited settings without infrastructures and equipment for growing TB cultures. Classical sequencing and NGS approaches have been successfully used in a recent study conducted in five countries with high burden of TB and multidrug resistant tuberculosis (MDR-TB) and aimed at investigating levels of resistance to pyrazinamide among patients with TB by pncA sequencing [doi: 10.1016/S1473-3099(16)30190-6]. This work innovatively demonstrated that the establishment of strong links between national (peripheral and reference laboratories) and supranational laboratories, with the former possibly processing indirect or direct samples and generating sequencing data, and the latter supporting them for bioinformatics analysis and data interpretation, will soon make WGS and targeted NGS the preferred tools to conduct public health surveillances in TB field, thus helping the strategies adopted by TB control programs at local and national levels.

Whole genome sequencing of Mycobacterium tuberculosis for detection of drug resistance: a systematic review

OBJECTIVES

We conducted a systematic review to determine the diagnostic accuracy of whole genome sequencing (WGS) of Mycobacterium tuberculosis for the detection of resistance to first- and second-line anti-tuberculosis (TB) drugs.

METHODS

The study was conducted according to the criteria of the Preferred Reporting Items for Systematic Reviews group. A total of 20 publications were included. The sensitivity, specificity, positive-predictive value and negative-predictive value of WGS using phenotypic drug susceptibility testing methods as a reference standard were determined.

RESULTS

Anti-TB agents tested included all first-line drugs, a variety of reserve drugs, as well as new drugs. Polymorphisms in a total of 53 genes were tested for associations with drug resistance. Pooled sensitivity and specificity values for detection of resistance to selected first-line drugs were 0.98 (95% CI 0.93-0.98) and 0.98 (95% CI 0.98-1.00) for rifampicin and 0.97 (95% CI 0.94-0.99) and 0.93 (95% CI 0.91-0.96) for isoniazid, respectively. Due to high heterogeneity in study designs, lack of data, knowledge of resistance mechanisms and clarity on exclusion of phylogenetic markers, there was a significant variation in analytical performance of WGS for the remaining first-line, reserved drugs and new drugs.

CONCLUSIONS

Whole genome sequencing could be considered a promising alternative to existing phenotypic and molecular drug susceptibility testing methods for rifampicin and isoniazid pending standardization of analytical pipelines. To ensure clinical relevance of WGS for detection of M. tuberculosis complex drug resistance, future studies should include information on clinical outcomes.

Survey of tuberculosis drug resistance among Tibetan refugees in India

SETTING

Tuberculosis (TB) is a major health problem among Tibetans living in exile in India. Although drug-resistant TB is considered common in clinical practice, precise data are lacking.

OBJECTIVE

To determine the proportion of drug-resistant cases among new and previously treated Tibetan TB patients.

DESIGN

In a drug resistance survey in five Tibetan settlements in India, culture and drug susceptibility testing (DST) for first-line drugs were performed among all consecutive new and previously treated TB cases from April 2010 to September 2011. DST against kanamycin (KM), ethionamide, para-aminosalicylic acid and ofloxacin (OFX) was performed on multidrug-resistant TB (MDR-TB) isolates.

RESULTS

Of 307 patients enrolled in the study, 264 (193 new and 71 previously treated) were culture-positive and had DST available. All patients tested for the human immunodeficiency virus (n = 250) were negative. Among new TB cases, 14.5% had MDR-TB and 5.7% were isoniazid (INH) monoresistant. Among previously treated cases, 31.4% had MDR-TB and 12.7% were INH-monoresistant. Of the MDR-TB isolates, 28.6% of new and 26.1% of previously treated cases were OFX-resistant, while 7.1% of new cases and 8.7% of previously treated cases were KM-resistant. Three patients had extensively drug-resistant TB.

CONCLUSIONS

MDR-TB is common in new and previously treated Tibetans in India, who also show additional complex resistance patterns. Of particular concern is the high percentage of MDR-TB strains resistant to OFX, KM or both.

Revisiting susceptibility testing in MDR-TB by a standardized quantitative phenotypic assessment in a European multicentre study

OBJECTIVES

Treatment outcome of MDR-TB is critically dependent on the proper use of second-line drugs as per the result of in vitro drug susceptibility testing (DST). We aimed to establish a standardized DST procedure based on quantitative determination of drug resistance and compared the results with those of genotypes associated with drug resistance.

METHODS

The protocol, based on MGIT 960 and the TB eXiST software, was evaluated in nine European reference laboratories. Resistance detection at a screening drug concentration was followed by determination of resistance levels and estimation of the resistance proportion. Mutations in 14 gene regions were investigated using established techniques.

RESULTS

A total of 139 Mycobacterium tuberculosis isolates from patients with MDR-TB and resistance beyond MDR-TB were tested for 13 antituberculous drugs: isoniazid, rifampicin, rifabutin, ethambutol, pyrazinamide, streptomycin, para-aminosalicylic acid, ethionamide, amikacin, capreomycin, ofloxacin, moxifloxacin and linezolid. Concordance between phenotypic and genotypic resistance was >80%, except for ethambutol. Time to results was short (median 10 days). High-level resistance, which precludes the therapeutic use of an antituberculous drug, was observed in 49% of the isolates. The finding of a low or intermediate resistance level in 16% and 35% of the isolates, respectively, may help in designing an efficient personalized regimen for the treatment of MDR-TB patients.

CONCLUSIONS

The automated DST procedure permits accurate and rapid quantitative resistance profiling of first- and second-line antituberculous drugs. Prospective validation is warranted to determine the impact on patient care.

Laboratory diagnosis of paediatric tuberculosis in the European Union/European Economic Area: analysis of routine laboratory data, 2007 to 2011

Laboratory confirmation of paediatric tuberculosis (TB) is frequently lacking. We reviewed the range of routine laboratory tests and their performance in different biological samples used to diagnose active TB in children. A questionnaire-based survey was conducted among the European Reference Laboratory Network for TB followed by collection of routine laboratory data on 10,549 paediatric samples tested in 2007 to 2011 at six reference laboratories (in Croatia, Germany, Italy, Latvia, Lithuania and the United Kingdom (UK)). The questionnaire showed that all laboratories used rapid assays. Non-respiratory samples were collected more often in Germany (135/275, 49.1%) and the UK (490/2,140, 22.9%) compared with Croatia (138/2,792, 4.9%), Latvia (222/2,401, 9.2%) and Lithuania (76/1,549, 4.9%). Overall laboratory positivity rates (isolation of Mycobacterium tuberculosis complex and/or identification of its nucleic acids in a sample) were higher in lymph node and gastric aspirate samples (14/203 (6.9%) and 43/1,231 (3.5%)) than in sputum samples (89/4,684 (1.9%)). Pooled sensitivity, specificity, positive and negative predictive values and accuracy of molecular assays assessed against solid or liquid culture were 79.2%, 93.6%, 67.1%, 96.5% and 91.6%, respectively. A more intensive approach in obtaining gastric aspirate and non-respiratory samples may increase laboratory confirmation of paediatric TB. Major effort is needed in optimisation and validation of molecular tests in these samples.

TBNET - Collaborative research on tuberculosis in Europe

Networking is a key feature of scientific success. The Tuberculosis Network European Trialsgroup (TBNET) was founded in 2006 as a non-profit, non-governmental peer-initiated scientific organization to collaboratively address research priorities in the area of tuberculosis in Europe. Today, TBNET is the largest tuberculosis research organization in Europe with nearly 500 members from 22 EU countries and 49 countries worldwide (www.tb-net.org). Apart from small multicenter basic research studies, a particular strength of TBNET is the performance of large collaborative projects, pan-European multicenter studies and database projects. In recent years, research from TBNET has substantially contributed to the understanding of the management, risk and prognosis of patients with multidrug (MDR) and extensively drug-resistant (XDR) tuberculosis and led to a better understanding of the clinical value of novel tests for the identification of adults and children with tuberculosis and latent infection with Mycobacterium tuberculosis. In 2009, two branches of TBNET were founded to specifically address tuberculosis in the pediatric population (ptbnet) and non-tuberculous mycobacterial diseases (NTM-NET). In addition to the research activities, TBNET is developing expert consensus documents for clinical management and provides training and capacity building especially for members from Eastern European countries, where tuberculosis is still a prevalent health problem.

European union standards for tuberculosis care

The European Centre for Disease Prevention and Control (ECDC) and the European Respiratory Society (ERS) jointly developed European Union Standards for Tuberculosis Care (ESTC) aimed at providing European Union (EU)-tailored standards for the diagnosis, treatment and prevention of tuberculosis (TB). The International Standards for TB Care (ISTC) were developed in the global context and are not always adapted to the EU setting and practices. The majority of EU countries have the resources and capacity to implement higher standards to further secure quality TB diagnosis, treatment and prevention. On this basis, the ESTC were developed as standards specifically tailored to the EU setting. A panel of 30 international experts, led by a writing group and the ERS and ECDC, identified and developed the 21 ESTC in the areas of diagnosis, treatment, HIV and comorbid conditions, and public health and prevention. The ISTCs formed the basis for the 21 standards, upon which additional EU adaptations and supplements were developed. These patient-centred standards are targeted to clinicians and public health workers, providing an easy-to-use resource, guiding through all required activities to ensure optimal diagnosis, treatment and prevention of TB. These will support EU health programmes to identify and develop optimal procedures for TB care, control and elimination.

TB and MDR/XDR-TB in European Union and European Economic Area countries: managed or mismanaged?

In spite of the growing awareness of emerging drug-resistant Mycobacterium tuberculosis, the extent of inappropriate tuberculosis (TB) case management may be underestimated, even in Europe. We evaluated TB case management in the European Union/European Economic Area countries, with special focus on multidrug-resistant (MDR) and extensively drug-resistant (XDR)-TB, using a purposely developed, standardised survey tool. National reference centres in five countries representing different geographical, socioeconomic and epidemiological patterns of TB in Europe were surveyed. 40 consecutive, original clinical TB case records (30 MDR/XDR-TB cases) were reviewed in each of the five countries. The findings were recorded and, through the survey tool, compared with previously agreed and identified international standards. Deviations from international standards of TB care were observed in the following areas: surveillance (no information available on patient outcomes); infection control (lack of respiratory isolation rooms/procedures and negative-pressure ventilation rooms); clinical management of TB, MDR-TB and HIV co-infection (inadequate bacteriological diagnosis, regimen selection and treatment duration); laboratory support; and diagnostic/treatment algorithms. Gaps between present international standards of care and the management of MDR/XDR-TB patients were identified. Training, increased awareness, promotion of standards and allocation of appropriate resources are necessary to ensure appropriate care and management as well as to prevent further emergence of drug resistance.

High risk of tuberculosis in health care workers in Romania

SETTING

The main university hospital in Iasi, Romania.

OBJECTIVE

To assess whether health care workers (HCWs) have a higher risk of acquiring tuberculosis (TB) than the general population, and if TB incidence varies between departments, to develop adequate infection control measures.

DESIGN

All records of TB cases among HCWs were reviewed by cross-checking laboratory and medical records (retrospectively, 1971--1996; prospectively 1997--2003, following the implementation of the first World Health Organization pilot project in Romania). Annual TB incidence rates among HCWs were calculated and compared with those of the general population; relative and attributable risk with 95% confidence intervals (CI) were calculated.

RESULTS

Fifty TB cases were diagnosed in HCWs; 42% were nurses, 24% ancillary staff, 12% physicians, 10% laboratory staff, 10% administrative staff and 2% radiology technicians. The mean incidence of TB in Romania during the study period was 96.8 per 100,000 persons/year (95%CI 83.5-110.1); the mean incidence among HCWs was 942.8/100,000 persons/year (95%CI 726.3-1159.3, P < 0.001); comparing the two previous absolute risks, the mean relative risk was 11 (95%CI 8-14) and the attributable risk 846.

CONCLUSION

TB is a major occupational hazard in Iasi, Romania, where a great potential exists for further development of an effective infection control plan.

Clinical and operational value of the extensively drug-resistant tuberculosis definition

Currently, no information is available on the effect of resistance/susceptibility to first-line drugs different from isoniazid and rifampicin in determining the outcome of extensively drug-resistant tuberculosis (XDR-TB) patients, and whether being XDR-TB is a more accurate indicator of poor clinical outcome than being resistant to all first-line anti-tuberculosis (TB) drugs. To investigate this issue, a large series of multidrug-resistant TB (MDR-TB) and XDR-TB cases diagnosed in Estonia, Germany, Italy and the Russian Federation during the period 1999-2006 were analysed. Drug-susceptibility testing for first- and second-line anti-TB drugs, quality assurance and treatment delivery was performed according to World Health Organization recommendations in all study sites. Out of 4,583 culture-positive TB cases analysed, 361 (7.9%) were MDR and 64 (1.4%) were XDR. XDR-TB cases had a relative risk (RR) of 1.58 to have an unfavourable outcome compared with MDR-TB cases resistant to all first-line drugs (isoniazid, rifampicin ethambutol, streptomycin and, when tested, pyrazinamide), and an RR of 2.61 compared with "other" MDR-TB cases (those susceptible to at least one first-line anti-TB drug among ethambutol, pyrazinamide and streptomycin, regardless of resistance to the second-line drugs not defining XDR-TB). The emergence of extensively drug-resistant tuberculosis confirms that problems in tuberculosis management are still present in Europe. While waiting for new tools which will facilitate management of extensively drug-resistant tuberculosis, accessibility to quality diagnostic and treatment services should be urgently ensured and adequate public health policies should be rapidly implemented to prevent further development of drug resistance.

First tuberculosis cases in Italy resistant to all tested drugs

Extensively Drug Resistant Tuberculosis (XDR-TB) is a very serious form of TB against which our treatment weapons have lost the majority of, if not all, their power

Use of a T-cell-based test for detection of tuberculosis infection among immunocompromised patients

The aim of this study was to compare the performance of the T-SPOT.TB test, a T-cell-based test, with the tuberculin skin test (TST) in the diagnosis of latent tuberculosis (TB) infection. The study was carried out in 138 immunosuppressed haematology patients who had been nosocomially exposed to a case of smear-positive TB. Overall, 44.2% of the contacts were positive by T-SPOT.TB test, and 17.4% by TST (concordance 67.8%). The apparent prevalence of infection fell from 25.9 to 14.5% with the TST with increasing immunosuppression, although this difference was not significant. In contrast, the apparent prevalence of infection with the T-SPOT.TB test was unaffected at 44.6 and 44.3%, respectively. The T-SPOT.TB test had an overall indeterminate rate of 4.3%, and this was also unaffected by the level of immunosuppression. This study suggests that the T-SPOT.TB test maintains its sensitivity and performance in immunocompromised patients, identifying a large number of truly infected patients anergic to the tuberculin skin test.

Direct rapid diagnosis of rifampicin-resistant M. tuberculosis infection in clinical samples by line probe assay (INNO LiPA Rif-TB)

M. tuberculosis is one of the leading causes of death worldwide and Multi Drug Resistant Tuberculosis (MDR-TB) is associated with a high case-fatality rate. Rapid identification of resistant strains is crucial to institute prompt appropriate therapy, and prevent the development of further resistance and spreading of MDR strains. The INNO-LiPA Rif. TB is a commercial reverse hybridisation line probe assay designed for rapid detection of rpoB gene mutations in clinical isolates. We applied this test directly to 44 smear-positive and 45 smear-negative clinical specimens collected from patients suspected of active TB. The capability of this technique to correctly identify local MDR-TB strains was tested on 50 MDR strains isolated in Italy. Results of the test were compared to conventional antibiogram performed on isolated strains. The concordance rate of the LiPA test results on clinical specimens with those obtained with "in vitro" sensitivity was 100%. These results show that the LiPA test can be useful in rapid detection and prompt management of tuberculosis when MDR disease is suspected.

Molecular approaches to the identification and treatment monitoring of periodontal pathogens

Two different PCR-based molecular approaches, a commercial kit for detection of A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus and T. denticola (Amplimedical "Paradonthosis") and a home-made multiplex PCR for A. actinomycetemcomitans, P. gingivalis and B. forsythus were compared for monitoring the efficacy of different dental treatments on localized persistent periodontal pockets. 44 sites were randomized in two treatment groups: mechanical treatment (22 control sites) and in conjunction with the application of tetracycline fibres (22 experimental sites). 40/44 sites were found positive with both tests for A. actinomycetemcomitans, P. gingivalis and B. forsythus pretheraphy. P. intermedia was detected alone in only three sites during the follow-up, while T. denticola. was always associated with the other pathogens. 20 sites were positive in conventional cultures for one to three of the pathogens. PCR-based approaches provided a sensitive and reliable method for identification and monitoring treatment of periodontal pathogens.

mig-14 is a horizontally acquired, host-induced gene required for salmonella enterica lethal infection in the murine model of typhoid fever

We have characterized a host-induced virulence gene, mig-14, that is required for fatal infection in the mouse model of enteric fever. mig-14 is present in all Salmonella enterica subspecies I serovars and maps to a region of the chromosome that appears to have been acquired by horizontal transmission. A mig-14 mutant replicated in host tissues early after infection but was later cleared from the spleens and livers of infected animals. Bacterial clearance by the host occurred concomitantly with an increase in gamma interferon levels and recruitment of macrophages, but few neutrophils, to the infection foci. We hypothesize that the mig-14 gene product may repress immune system functions by interfering with normal cytokine expression in response to bacterial infections.

Macrophage-dependent induction of the Salmonella pathogenicity island 2 type III secretion system and its role in intracellular survival

Salmonella pathogenicity island 2 (SPI-2) encodes a putative type III secretion system necessary for systemic infection in animals. We have investigated the transcriptional organization and regulation of SPI-2 by creating gfp fusions throughout the entire gene cluster. These gfp fusions demonstrated that SPI-2 genes encoding structural, regulatory and previously uncharacterized putative secreted proteins are preferentially expressed in the intracellular environment of the host macrophage. Furthermore, the transcription of these genes within host cells was dependent on the two-component regulatory system SsrA/SsrB and an acidic phagosomal environment. Most SPI-2 mutants failed to replicate to the same level as wild-type strains in murine macrophages and human epithelial cells. In orally infected mice, SPI-2 mutants colonized the Peyer's patches but did not progress to the mesenteric lymph nodes. We conclude that SPI-2 genes are specifically expressed upon entry into mammalian cells and are required for intracellular growth in host cells in vivo and in vitro.

Identification of a domain in Rck, a product of the Salmonella typhimurium virulence plasmid, required for both serum resistance and cell invasion

Rck is encoded on the Salmonella typhimurium virulence plasmid and is a member of a family of related 17- to 19-kDa outer membrane proteins of Enterobacteriaceae, including Ail (Yersinia enterocolitica) and PagC (S. typhimurium). Structural models for these proteins predict eight membrane-spanning domains alternating with hydrophilic inner and outer loops. When expressed in Escherichia coli, Rck and Ail, but not PagC, confer high-level resistance to the bactericidal activity of complement as well as the ability to adhere to and invade mammalian cell lines. To identify functional domains of Rck, we made and screened random mutations in Rck for decreased bioactivity. We found that a single amino acid substitution (glycine to aspartic acid) in the putative third outer loop greatly reduced Rck-mediated serum resistance and eukaryotic cell invasion. We then constructed two chimeric proteins between Rck and PagC. Substitution of the C-terminal half of Rck with the corresponding PagC fragment containing both the third and the fourth outer loops abolishes the Rck-mediated serum resistance and invasion phenotypes. Substitution of Rck with a smaller C-terminal portion of PagC containing the fourth outer loop did not affect the invasive phenotype or serum resistance. These data reveal that the third putative outer membrane loop region is important for the virulence-associated properties of the Rck protein and suggest a similarity between the mechanism of serum resistance and epithelial cell invasion involving the same domain of Rck.

Epidemiological characteristics of Pseudomonas aeruginosa strains causing infection in an Italian general hospital. A one-year surveillance

During the 1989 calendar year, P. aeruginosa caused clinical infections in 0.46% of patients admitted to Ospedali Riuniti (a general hospital), Bergamo, Italy. Strains (n = 267) of P. aeruginosa were collected during this period, and epidemiological characteristics were studied. The mean prevalence of P. aeruginosa infection in inpatients was 1.1% (range 0.06-7.3), whereas outpatients showed a significantly lower prevalence of infection (0.05%). Strains were recovered from inpatients of surgical wards (n = 126; 47.2%), and outpatients (n = 15; 5.6%). Males were more often affected than females (2.7:1). Infection of the urinary tract was the most common (34.1%). Pseudomonas aeruginosa was also involved in lower respiratory tract infections (18.7%) and septicaemia (17.6%). Four typing methods were performed, i.e. serotyping, antibiotyping, pyocin typing, and restriction endonuclease analysis (REA). Serotypes O:11 and O:6 were endemic in the hospital. Some serotypes correlated with specific clinical wards. Pyocin typing was an unreliable epidemiological tool. However, antibiotyping showed the presence of some epidemic clusters, probably related to the antibiotic consumption of the patients. REA suggested the circulation of edemic P. aeruginosa strains in both the obstetrics and neurosurgery wards.

Receptor for bombesin with associated tyrosine kinase activity

The neuropeptide bombesin is known for its potent mitogenic activity on murine 3T3 fibroblasts and other cells. Recently it has been implicated in the pathogenesis of small cell lung carcinoma, in which it acts through an autocrine loop of growth stimulation. Phosphotyrosine (P-Tyr) antibodies have been successfully used to recognize the autophosphorylated receptors for known growth factors. In Swiss 3T3 fibroblasts, phosphotyrosine antibodies identified a 115,000-Mr cell surface protein (p115) that became phosphorylated on tyrosine as a specific response to bombesin stimulation of quiescent cells. The extent of phosphorylation was dose dependent and correlated with the mitogenic effect induced by bombesin, measured by [3H]thymidine incorporation. Tyrosine phosphorylation of p115 was detectable minutes after the addition of bombesin, and its time course paralleled that described for the binding of bombesin to its receptor. Immunocomplexes of phosphorylated p115 and phosphotyrosine antibodies bound 125I-labeled [Tyr4]bombesin in a specific and saturable manner and displayed an associated tyrosine kinase activity enhanced by bombesin. Furthermore, the 125I-labeled bombesin analog gastrin-releasing peptide, bound to intact live cells, was coprecipitated with p115. These data strongly suggest that p115 participates in the structure and function of the surface receptor for bombesin, a new member of the family of growth factor receptors with associated tyrosine kinase activity.

Phosphotyrosine antibodies identify the p210c-abl tyrosine kinase and proteins phosphorylated on tyrosine in human chronic myelogenous leukemia cells

Antibodies against phosphotyrosine are a powerful tool with which to identify proteins phosphorylated on tyrosine residues, such as viral oncogene-encoded transforming proteins and their cellular protein substrates. Probed on human leukemia cell lines, phosphotyrosine antibodies recognized a 210,000-molecular-weight protein (p210) in K562 cells, a cell line derived from a Philadelphia (Ph)'-positive chronic myelogenous leukemia (CML), but recognized no protein in control Ph'-negative non-CML leukemia cells. The p210 protein was also recognized by antisera against v-abl-encoded polypeptides and displayed kinase activity, phosphorylating itself on tyrosine, in an immunocomplex kinase assay. These data are consistent with reported findings of the expression of a recombined bcr-abl gene in Ph'-positive CML cells, leading to the synthesis of an altered p210c-abl protein endowed with tyrosine kinase activity. Phosphotyrosine antibodies also detected the expression of the p210c-abl protein in fresh bone marrow cells harvested from CML patients in blast crisis. Besides the p210c-abl protein kinase, phosphotyrosine antibodies recognized other proteins with molecular weights of 110,000, 68,000, and 36,000 (p110, p68, and p36) in K562 cells. When [gamma-32P]ATP was added to nonionic detergent-extracted cells, these proteins became phosphorylated on tyrosine, as confirmed by phosphoamino acid analysis. A comparison with fibroblasts transformed by the v-abl, v-src, and v-fps oncogenes suggested the identity of the p36 protein with the common 36-kilodalton protein substrate of viral oncogene-encoded tyrosine kinases. Enhanced tyrosine phosphorylation of cellular proteins is thus a feature shared by cells transformed by v-abl and cells expressing a rearranged bcr-abl gene.