The relative transmission fitness of multidrug-resistant Mycobacterium tuberculosis in a drug resistance hotspot.

Multidrug-resistant tuberculosis (MDR-TB) is among the most frequent causes of death due to antimicrobial resistance. Although only 3% of global TB cases are MDR, geographical hotspots with up to 40% of MDR-TB have been observed in countries of the former Soviet Union. While the quality of TB control and patient-related factors are known contributors to such hotspots, the role of the pathogen remains unclear.

Back-to-Africa introductions of Mycobacterium tuberculosis as the main cause of tuberculosis in Dar es Salaam, Tanzania.

In settings with high tuberculosis (TB) endemicity, distinct genotypes of the Mycobacterium tuberculosis complex (MTBC) often differ in prevalence. However, the factors leading to these differences remain poorly understood. Here we studied the MTBC population in Dar es Salaam, Tanzania over a six-year period, using 1,082 unique patient-derived MTBC whole-genome sequences (WGS) and associated clinical data.

Developing customized stepwise MIRU-VNTR typing for tuberculosis surveillance in Georgia.

Introduction: Mycobacterial Interspersed Repetitive Units-Variable Tandem Repeats (MIRU-VNTR) typing has been widely used for molecular epidemiological studies of tuberculosis (TB). However, genotyping tools for Mycobacterium tuberculosis (Mtb) may be limiting in some settings due to high cost and workload. In this study developed a customized stepwise MIRU-VNTR typing that prioritizes high discriminatory loci and validated this method using penitentiary system cohort in the country of Georgia.

Prisons as ecological drivers of fitness-compensated multidrug-resistant Mycobacterium tuberculosis.

Multidrug-resistant tuberculosis (MDR-TB) accounts for one third of the annual deaths due to antimicrobial resistance. Drug resistance-conferring mutations frequently cause fitness costs in bacteria. Experimental work indicates that these drug resistance-related fitness costs might be mitigated by compensatory mutations.

Local adaptation in populations of endemic to the Indian Ocean Rim.

Lineage 1 (L1) and 3 (L3) are two lineages of the complex (MTBC) causing tuberculosis (TB) in humans. L1 and L3 are prevalent around the rim of the Indian Ocean, the region that accounts for most of the world's new TB cases. Despite their relevance for this region, L1 and L3 remain understudied.

Classifying recurrent Mycobacterium tuberculosis cases in Georgia using MIRU-VNTR typing.

Introduction: Recurrent tuberculosis (TB) is one of the main challenges in TB control. Genotyping based on Mycobacterial Interspersed Repetitive Units-Variable Tandem Repeats (MIRU-VNTR) has been widely used to differentiate between relapse and reinfection, which are the two main causes of recurrent TB. There is a lack of data regarding the causes of TB recurrence in Georgia, and while differentiating between relapse and reinfection plays a key role in defining appropriate interventions, the required genotyping methodologies have not been implemented.

Preservation of sputum samples with cetylpyridinium chloride (CPC) for tuberculosis cultures and Xpert MTB/RIF in a low-income country.

Background: Culture contamination with environmental bacteria is a major challenge in tuberculosis (TB) laboratories in hot and humid climate zones. We studied the effect of cetylpyridinium chloride (CPC) preservation on culture results and performance of Xpert MTB/RIF.

Methods: Consecutive sputum samples from microscopy smear-positive TB patients were collected.

Blood and urine inducible protein 10 as potential markers of disease activity.

Setting: Blood interferon-γ inducible protein 10 (IP-10) has been proposed as a biomarker of disease activity for both tuberculosis (TB) and human immunodeficiency virus (HIV) infection. Urine IP-10 has been detected in adults with active TB, and its level decreases after successful anti-tuberculosis treatment.

Objective: To evaluate blood and urine IP-10 as biomarker of disease activity.

Tuberculous spondylitis diagnosed through Xpert MTB/RIF assay in urine: a case report.

Background: Extrapulmonary tuberculosis (EPTB) is associated with high rates of morbidity and mortality. Diagnosis of EPTB is challenging in resource-limited settings due to difficulties in obtaining samples, as well as the paucibacillarity of the specimens. Skeletal tuberculosis accounts for 10-35 % of EPTB cases, with vertebral osteomyelitis (Pott's disease) representing 50 % of the cases.

Limited value of whole blood Xpert(®) MTB/RIF for diagnosing tuberculosis in children.

Objectives: We evaluated the ability of the Xpert(®) MTB/RIF assay to detect Mycobacterium tuberculosis in whole blood of children with tuberculosis in tuberculosis endemic settings with high rates of HIV infection.

Methods: From June 2011 to September 2012 we prospectively enrolled children with symptoms or signs suggestive of tuberculosis at three research centres in Tanzania and Uganda. After clinical assessment, respiratory specimens were collected for microscopy and culture, as well as whole blood for Xpert(®) MTB/RIF.

Evaluation of Xpert® MTB/RIF and Ustar EasyNAT™ TB IAD for diagnosis of tuberculous lymphadenitis of children in Tanzania: a prospective descriptive study.

Background: Fine needle aspiration biopsy has become a standard approach for diagnosis of peripheral tuberculous lymphadenitis. The aim of this study was to compare the performance of Xpert MTB/RIF and Ustar EasyNAT TB IAD nucleic acid amplification assays, against acid-fast bacilli microscopy, cytology and mycobacterial culture for the diagnosis of TB lymphadenitis in children from a TB-endemic setting in Tanzania.

Methods: Children of 8 weeks to 16 years of age, suspected of having TB lymphadenitis, were recruited at a district hospital in Tanzania.

Direct Susceptibility Testing of Mycobacterium tuberculosis for Pyrazinamide by Use of the Bactec MGIT 960 System.

Pyrazinamide (PZA) is a key antituberculosis drug, yet no rapid susceptibility test is commercially available. PZA drug susceptibility testing (DST) was performed directly on sputum samples from 327 patients and compared with the indirect method by using the Bactec MGIT 960 system in the context of patient screening for participation in a drug trial. Compared to standard indirect PZA DST, direct DST was successful in only 59% of cases, but results obtained were highly accurate and available faster.

Evaluation of Giant African Pouched Rats for Detection of Pulmonary Tuberculosis in Patients from a High-Endemic Setting.

Background: This study established evidence about the diagnostic performance of trained giant African pouched rats for detecting Mycobacterium tuberculosis in sputum of well-characterised patients with presumptive tuberculosis (TB) in a high-burden setting.

Methods: The TB detection rats were evaluated using sputum samples of patients with presumptive TB enrolled in two prospective cohort studies in Bagamoyo, Tanzania. The patients were characterised by sputum smear microscopy and culture, including subsequent antigen or molecular confirmation of Mycobacterium tuberculosis, and by clinical data at enrolment and for at least 5-months of follow-up to determine the reference standard.

Blood or Urine IP-10 Cannot Discriminate between Active Tuberculosis and Respiratory Diseases Different from Tuberculosis in Children.

Objectives: Interferon-γ inducible protein 10 (IP-10), either in blood or in urine, has been proposed as a tuberculosis (TB) biomarker for adults. This study aims to evaluate the potential of IP-10 diagnostics in children from Uganda, a high TB-endemic country.

Methods: IP-10 was measured in the blood and urine concomitantly taken from children who were prospectively enrolled with suspected active TB, with or without HIV infection.

Detection of Mycobacterium tuberculosis by EasyNAT diagnostic kit in sputum samples from Tanzania.

The EasyNAT assay was evaluated for the detection of tuberculosis in sputum smears from presumptive pulmonary tuberculosis (TB) patients in an African high-TB and high-HIV setting. The sensitivity of the EasyNAT assay was 66.7%, and the specificity and positive predictive value were 100% for the culture-positive patients.

Xpert MTB/RIF assay for diagnosis of pulmonary tuberculosis in children: a prospective, multi-centre evaluation.

Background: Following endorsement by the World Health Organisation, the Xpert MTB/RIF assay has been widely incorporated into algorithms for the diagnosis of adult tuberculosis (TB). However, data on its performance in children remain scarce. This prospective, multi-centre study evaluated the performance of Xpert MTB/RIF to diagnose pulmonary tuberculosis in children.

Diagnostic accuracy of computer-aided detection of pulmonary tuberculosis in chest radiographs: a validation study from sub-Saharan Africa.

Background: Chest radiography to diagnose and screen for pulmonary tuberculosis has limitations, especially due to inter-reader variability. Automating the interpretation has the potential to overcome this drawback and to deliver objective and reproducible results. The CAD4TB software is a computer-aided detection system that has shown promising preliminary findings.

Assessment of the novel T-cell activation marker-tuberculosis assay for diagnosis of active tuberculosis in children: a prospective proof-of-concept study.

Background: The diagnosis of paediatric tuberculosis is complicated by non-specific symptoms, difficult specimen collection, and the paucibacillary nature of the disease. We assessed the accuracy of a novel immunodiagnostic T-cell activation marker-tuberculosis (TAM-TB) assay in a proof-of-concept study to identify children with active tuberculosis.

Methods: Children with symptoms that suggested tuberculosis were prospectively recruited at the NIMR-Mbeya Medical Research Center in Mbeya, and the Ifakara Health Institute in Bagamoyo, Tanzania, between May 10, 2011, and Sept 4, 2012.

High level of cross-resistance between kanamycin, amikacin, and capreomycin among Mycobacterium tuberculosis isolates from Georgia and a close relation with mutations in the rrs gene.

The aminoglycosides kanamycin and amikacin and the macrocyclic peptide capreomycin are key drugs for the treatment of multidrug-resistant tuberculosis (MDR-TB). The increasing rates of resistance to these drugs and the possible cross-resistance between them are concerns for MDR-TB therapy. Mutations in the 16S rRNA gene (rrs) have been associated with resistance to each of the drugs, and mutations of the tlyA gene, which encodes a putative rRNA methyltransferase, are thought to confer capreomycin resistance in Mycobacterium tuberculosis bacteria.

High levels of resistance to second-line anti-tuberculosis drugs among prisoners with pulmonary tuberculosis in Georgia.

Setting: Penitentiary system of Georgia.

Objective: To determine the prevalence of resistance to second-line drugs among prisoners with pulmonary tuberculosis (PTB).

Design: Retrospective evaluation of resistance to second-line drugs in tuberculosis (TB) patients treated from 2001 to 2003.

Mixed infection and clonal representativeness of a single sputum sample in tuberculosis patients from a penitentiary hospital in Georgia.

Background: Studies on recurrent tuberculosis (TB), TB molecular epidemiology and drug susceptibility testing rely on the analysis of one Mycobacterium tuberculosis isolate from a single sputum sample collected at different disease episodes. This scheme rests on the postulate that a culture of one sputum sample is homogeneous and representative of the total bacillary population in a patient.

Methods: We systematically analysed several pre-treatment isolates from each of 199 smear-positive male adult inmates admitted to a prison TB hospital by standard IS6110 DNA fingerprinting, followed by PCR typing based on multiple loci containing variable number of tandem repeats (VNTRs) on a subset of isolates.