A retrospective analysis of isoniazid-monoresistant tuberculosis: among Iranian pulmonary tuberculosis patients

Epidemiology of first- and second-line drugs-resistant pulmonary tuberculosis in Iran: Systematic review and meta-analysis

Drug resistance among Mycobacterium tuberculosis (MTB) strains is a growing concern in developing countries. We conducted a comprehensive search for relevant studies in Iran on PubMed, Scopus, and Embase until June 12, 2020. Our study focused on determining the prevalence of antibiotic resistance in MTB isolates, with subgroup analyses based on year, location, and drug susceptibility testing (DST) methods. Statistical analyses were performed using STATA software. Our meta-analysis included a total of 47 articles. Among new TB cases, we found the following prevalence rates: Any-resistance to first-line drugs: 31 % (95 % CI, 24-38), mono-drug resistance: 15 % (95 % CI, 10-22), and multidrug resistance to first-line drugs: 6 % (95 % CI, 4-8). There was a significant variation in the rate of MDR among new TB cases based on the year of publication, location, and DST methods (P < 0.0001). We observed substantial variability in multidrug-resistant TB rates among new cases across the studies. Stratified analyses revealed that publication years and DST methods significantly affected resistance rates. Studies from southern and central Iran reported higher any-drug resistance rates, suggesting regional differences. Among retreatment cases, the prevalence rates were as follows: Any resistance: 68 % (95 % CI 58-78), mono-resistance: 19 % (95 % CI 7-34), multidrug resistance: 28 % (95 % CI 15-43). Our study revealed that the prevalence of drug-resistant TB (DR-TB) among TB cases in Iran is higher than the global average. Particularly, MDR-TB among retreatment TB cases is a significant public health issue.

Rifampicin resistance in Mycobacterium tuberculosis in Iran: a two-centre study

Multidrug-resistant tuberculosis remains a challenge. In this study, we investigated the incidence of rifampicin (RIF) resistance in Mycobacterium tuberculosis in a large number of pulmonary specimens. A two-center study in Tehran, the capital of Iran, was performed with 6624 pulmonary samples of patients with tuberculosis (TB) who were subjected to detection of RIF-resistant TB by GeneXpert MTB/RIF assay between May 2014 and July 2018. Conventional drug susceptibility testing was performed to confirm the results. Xpert MTB/RIF identified a total of 96 positives for M. tuberculosis, of which 5 (5.3%) samples were found to be RIF-resistant TB. All RIF-resistant and sensitive isolates detected by GeneXpert were phenotypically confirmed by drug susceptibility testing. These results indicated that the Xpert MTB/RIF test can be used as a rapid diagnostic method and can potentially decrease the morbidity associated with diagnostic delay and mistreatment.

Detection of genomic mutations in katG and rpoB genes among multidrug-resistant Mycobacterium tuberculosis isolates from Tehran, Iran

Multidrug-resistant (MDR) Mycobacterium tuberculosis strains, defined as resistant to at least isoniazid and rifampin, have emerged as a major worldwide health threat. Spontaneous point mutations in various genes of M. tuberculosis cause resistance to isoniazid, with the most frequent gene target being katG; and resistance to rifampin is usually due to mutation in the rpoB gene. The current study was aimed to detect the point mutations in the katG and rpoB regions related to isoniazid and rifampin resistance. A total of 203 respiratory specimens were collected from patients suspected of having tuberculosis respiratory infections referred to hospitals of Tehran, Iran, during 2018-2019. The isolation and identification of M. tuberculosis isolates were performed according to the WHO protocol. Drug susceptibility testing was carried out by proportional method. PCR analysis and sequencing were used to detect mutations in the selected katG and rpoB regions. Forty-four M. tuberculosis strains were isolated, of which 12 (27.3%) and 10 (22.7%) were resistant to isoniazid and rifampin, respectively. Ten isolates were resistant to both isoniazid and rifampin and were considered as MDR isolates. Of the ten MDR isolates, six (60%) carried mutations in both rpoB and katG. The most common mutations among isoniazid- and rifampin-resistant isolates were in codon 315 of the katG gene (70%) and codon 441 of the rpoB gene (50%), respectively. The results of this study indicated that MDR-TB continues to be a serious public health problem in Iran.

Accuracy of molecular drug susceptibility testing amongst tuberculosis patients in Karakalpakstan, Uzbekistan

OBJECTIVES

In this retrospective study, we evaluated the diagnostic accuracy of molecular tests (MT) for the detection of DR-TB, compared to the gold standard liquid-based drug susceptibility testing (DST) in Karakalpakstan.

METHODS

A total of 6670 specimens received in the Republican TB No 1 Hospital Laboratory of Karakalpakstan between January and July 2017 from new and retreatment patients were analysed. Samples were tested using Xpert MTB/RIF and line probe assays (LPA) for the detection of mutations associated with resistance. The sensitivity and specificity of MTs were calculated relative to results based on DST.

RESULTS

The accuracy of MT for detection of rifampicin resistance was high, with sensitivity and specificity over 98%. However, we observed reduced sensitivity of LPA for detection of resistance; 86% for isoniazid (95% CI 82-90%), 86% for fluoroquinolones (95% CI 68-96%), 70% for capreomycin (95% CI 46-88%) and 23% for kanamycin (95% CI 13-35%).

CONCLUSIONS

We show that MTs are a useful tool for rapid and safe diagnosis of DR-TB; however, clinicians should be aware of their limitations. Although detection of rifampicin resistance was highly accurate, our data suggest that resistance mutations circulating in the Republic of Karakalpakstan for other drugs were not detected by the methods used here. This merits further investigation.

Genotyping and drug susceptibility testing of Mycobacterium tuberculosis in Iran: a multi-centre study

Tuberculosis (TB) is a deadly infection and caused 1.4 million deaths in 2018. Assessing the geographic distribution of major lineages of Mycobacterium tuberculosis can contribute greatly to TB control. Mycobacterial interspersed repetitive unit variable number tandem repeat (MIRU-VNTR) typing is commonly used to differentiate various lineages of M. tuberculosis. A total of 2747 clinical specimens were collected consecutively from October 2018 through June 2019. Clinical isolates were identified as M. tuberculosis using standard biochemical tests. The standard 15-locus MIRU-VNTR typing was used for the genotyping of clinical isolates. Drug susceptibility testing was performed using the conventional proportion method. From the collected specimens, 100 were culture positive for M. tuberculosis. Using MIRU-VNTR, 99 different patterns were detected among the 100 isolates. They were distributed in one cluster comprising two strains and 98 unique patterns. Most of our isolates were similar to New-1 and Delhi/CAS strains. Of the M. tuberculosis isolates, 83 (83.0%) were pan-susceptible and 17 (17.0%) were resistant to at least one drug. Our study showed that MIRU-VNTR is a useful method for studying the genetic diversity of M. tuberculosis isolates in different regional settings and will help the health authorities to construct a preventive programme for TB.

High-resolution melt curve analysis for rapid detection of rifampicin resistance in Mycobacterium tuberculosis: a single-centre study in Iran

This study aimed to compare the diagnostic accuracy of high-resolution melting (HRM) analysis in comparison with Xpert MTB/RIF as well as conventional drug susceptibility testing (DST) for the detection of rifampicin (RIF) resistance in Mycobacterium tuberculosis in Iran. A comparative cross-sectional study was carried out from April 2017 to September 2018. A total of 80 culture-positive clinical samples selected during the study period were analysed for detection of RIF-resistant TB by conventional DST, Xpert MTB/RIF, and sequencing. Sensitivity and specificity of the HRM calculated according to DST was our reference standard test in this study. The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HRM assay were found to be 100%, 89.33%, 38.46%, and 100% respectively. The analysis demonstrated that the diagnostic accuracy of HRM tests is insufficient to replace Xpert MTB/RIF and conventional DST. HRM tests have the advantage of time to result and may be used in combination with culture. Further work to improve molecular tests would benefit from standardized reference standards and the methodology.

Low diagnostic accuracy of Xpert MTB/RIF assay for extrapulmonary tuberculosis: A multicenter surveillance

Diagnostic accuracy of Xpert MTB/RIF assay for pulmonary tuberculosis (PTB) and extrapulmonary TB (EPTB) has not been investigated in Iran. This study was aimed to assess the diagnostic accuracy of Xpert MTB/RIF assay for both PTB and EPTB. A total of 2111 clinical samples (1218 pulmonary and 838 extra-pulmonary) were collected from 16 medical centers during the study period and were analyzed for detection of PTB and EPTB by both Xpert MTB/RIF assay and standard conventional methods (culture and direct smear microscopy). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Xpert MTB/RIF assay for PTB were found to be 95.5%, 96.7%, 83.8%, and 99.1% respectively. For EPTB, the sensitivity, specificity, PPV and NPV of Xpert MTB/RIF assay counted for 76.5%, 95.9%, 62%, and 97.9% respectively. Xpert MTB/RIF assay found to be highly sensitive, specific and comparable to standard conventional methods for the diagnosis of PTB. However, the sensitivity and specificity of Xpert MTB/RIF for EPTB specimens were highly variable; thus, Xpert MTB/RIF cannot be recommended to replace standard conventional tests for diagnosis of EPTB.

Factors associated with isoniazid resistant tuberculosis among human immunodeficiency virus positive patients in Swaziland: a case-control study

Background

Isoniazid resistant tuberculosis is the most prevalent type of resistance in Swaziland and over two-thirds of the isoniazid resistant tuberculosis patients are tuberculosis and human immunodeficiency virus co-infected. The study aimed to determine risk factors associated with isoniazid resistant tuberculosis among human immunodeficiency virus positive patients in Swaziland.

Methods

This was a case-control study conducted in nine healthcare facilities across Swaziland. Cases were patients with isoniazid resistant tuberculosis (including 78 patients with isoniazid mono-resistant tuberculosis, 42 with polydrug-resistant tuberculosis, and 77 with multidrug-resistant tuberculosis). Controls were presumed drug-susceptible tuberculosis patients (n = 203). Multinomial logistic regression was used to determine related factors.

Results

The median time lag from diagnosis to tuberculosis treatment initiation was 50 days for isoniazid mono or poly drug-resistant tuberculosis, 17 days for multidrug-resistant tuberculosis compared to 1 day for drug-susceptible tuberculosis patients. History of previous tuberculosis treatment was positively associated with either isoniazid mono or poly drug-resistant tuberculosis (OR = 7.91, 95% CI: 4.14–15.11) and multidrug-resistant tuberculosis (OR = 12.20, 95% CI: 6.07–24.54). Isoniazid mono or poly resistant tuberculosis patients were more likely to be from rural areas (OR = 2.05, 95% CI: 1.23–3.32) and current heavy alcohol drinkers compared to the drug-susceptible tuberculosis group. Multi drug-resistant tuberculosis patients were more likely to be non-adherent to tuberculosis treatment compared to drug-susceptible tuberculosis group (OR = 3.01, 95% CI: 1.56–5.82).

Conclusion

To prevent and control isoniazid resistant tuberculosis among HIV-positive patients in Swaziland, the tuberculosis program should strengthen the use of rapid diagnostic tests, detect resistance early, promptly initiate supervised tuberculosis treatment and decentralize quality tuberculosis services to the rural areas. Adherence to tuberculosis treatment should be improved.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4384-6) contains supplementary material, which is available to authorized users.

Trends in multidrug-resistant tuberculosis in Tehran, Iran: an analysis of published data

Introduction: Multidrug-resistant tuberculosis (MDR-TB) is one of the major public health threats especially in developing countries. In Iran, the emergence and spread of MDR-TB are likely to pose a significant problem for the National Tubeculosis Control Program (NTP). In this study, to determine the trend of MDR-TB in Tehran, the results of published studies were analyzed.

Methods: Several databases were searched, including Medline, Embase, Web of Science and Iranian databases. Studies which report the prevalence of MDR-TB by World Health Organization (WHO)-endorsed drug susceptibility testing (DST) methods were included in the study. Data were analyzed with SPSS 20 (SPSS, Chicago, Illinois, USA).

Results: Analysis of the MDR-TB trend did not show any increase among new TB cases, but the trend of MDR-TB was significantly increased among previously treated cases. The prevalence of MDR-TB from 48.0% in 1996 reached 58.0% in 2004 (P<0.05).

Conclusions: Our analysis shows an increasing trend in MDR-TB, particularly in retreatment cases. This study strongly highlights the need to develop further strategies for surveillance, monitoring, and management of MDR-TB cases.

Isoniazid mono-resistant tuberculosis: Time to take it seriously

BACKGROUND/AIMS

In drug resistant tuberculosis (DRTB) suspects, rifampicin resistance has always been prioritized, hence Cartridge Based Nucleic Acid Amplification Test (CBNAAT) is recommended under Revised National Tuberculosis Control Programme (RNTCP), India. However, since it doesn't detect isoniazid resistance, rifampicin sensitive patients with unknown isoniazid status may be erroneously treated as drug sensitive TB, leading to poor treatment outcomes and emergence of multidrug resistant (MDR) TB. Hence isoniazid mono-resistance should be specifically looked for and treated as per recommendations. The objective of the present study, almost the first of its kind in India, was to evaluate the burden of isoniazid mono-resistance amongst patients diagnosed with DRTB and to study the association of different patient and disease related factors with treatment outcomes under the treatment regimen specific for isoniazid mono-resistance, started from January 1, 2017 in our state, under RNTCP.

METHODS

It was a retrospective study which scrutinized medical records of 52 isoniazid mono-resistant TB patients started on treatment under RNTCP between January 1 to December 31, 2017. Necessary information on possible patient and disease related predicting factors like gender, age, type of mutation (katG/inhA), weight band (26-45 kg/46-70 kg), total serum protein/albumin levels, previous history of anti-tubercular treatment (ATT), history of smoking, HIV status, presence of diabetes mellitus (DM), presence of anemia, occurrence of adverse drug reactions (ADR) during treatment and duration of intensive phase (IP), was retrieved. These factors were analyzed for their possible association with treatment outcomes.

RESULTS

Out of 103 DRTB patients enrolled, 50.5% (52/103) patients were diagnosed with isoniazid mono-resistance. 50/103 were MDR-TB and 1/103 were extensively-drug resistant TB (XDR-TB). Further analysis of these 52 isoniazid mono-resistant patients revealed:35 (67.3%) were males and 17 (32.7%) females. 27 (51.9%) patients were <30 years, 25 (48.1%) being ≥30 years of age. All patients were negative for HIV. 34/52 (65.4%) patients were declared cured, 15/52 were lost to follow up (LTFU) and 3/52 died (1 male, 2 females). Excluding these 3 patients who died, cure rates were significantly better in females (14/15 = 93.3%), with only 1/15 LTFU, than males (20/34 = 58.8% cure, 14/34 = 41.2% LTFU), (p = 0.019). Patients who were <30 years of age had significantly better cure rates (21/25 = 84%) with lesser LTFU's (4/25 = 16%), than those ≥30years of age (13/24 = 54.2% cure, 11/24 = 45.8% LTFU), (p = 0.032). Review of previous history of ATT revealed that 33 patients had primary isoniazid mono-resistance, 4 patients had previous history of being LTFU, 9 had recurrent TB and 3 were labeled as failure. Cure rates were significantly better in primary isoniazid mono-resistant patients (26/33 = 78.8%), than those with previous history of being LTFU(0/4), (p = 0.04). Type of mutation, weight band, total serum protein/albumin, history of smoking, presence of DM, presence of anemia, occurrence of ADR and duration of IP did not affect treatment outcomes.

CONCLUSION

Isoniazid mono-resistance formed a major chunk of DRTB, with majority of the patients detected with primary mono-resistance. Strategically framed treatment regimens for isoniazid mono-resistance under RNTCP in India are effective in a wide range of population. Still, there are high chances of LTFU/default, which needs to be addressed on priority. Male gender, age ≥30 years and being LTFU in the past are associated with poorer cure rates, hence should be paid special attention.

Isoniazid Mono-Resistant Tuberculosis: Impact on Treatment Outcome and Survival of Pulmonary Tuberculosis Patients in Southern Mexico 1995-2010

Background

Isoniazid mono-resistance (IMR) is the most common form of mono-resistance; its world prevalence is estimated to range between 0.0 to 9.5% globally. There is no consensus on how these patients should be treated.

Objective

To describe the impact of IMR tuberculosis (TB) on treatment outcome and survival among pulmonary TB patients treated under programmatic conditions in Orizaba, Veracruz, Mexico.

Materials and Methods

We conducted a prospective cohort study of pulmonary TB patients in Southern Mexico. From 1995 to 2010 patients with acid-fast bacilli or culture proven Mycobacterium tuberculosis in sputum samples underwent epidemiological, clinical and microbiological evaluation. We included patients who harbored isoniazid mono-resistant (IMR) strains and patients with strains susceptible to isoniazid, rifampicin, ethambutol and streptomycin. All patients were treated following Mexican TB Program guidelines. We performed annual follow-up to ascertain treatment outcome, recurrence, relapse and mortality.

Results

Between 1995 and 2010 1,243 patients with pulmonary TB were recruited; 902/1,243 (72.57%) had drug susceptibility testing; 716 (79.38%) harbored pan-susceptible and 88 (9.75%) IMR strains. Having any contact with a person with TB (adjusted odds ratio (aOR)) 1.85, 95% Confidence interval (CI) 1.15–2.96) and homelessness (adjusted odds ratio (aOR) 2.76, 95% CI 1.08–6.99) were associated with IMR. IMR patients had a higher probability of failure (adjusted hazard ratio (HR) 12.35, 95% CI 3.38–45.15) and death due to TB among HIV negative patients (aHR 3.30. 95% CI 1.00–10.84). All the models were adjusted for socio-demographic and clinical variables.

Conclusions

The results from our study provide evidence that the standardized treatment schedule with first line drugs in new and previously treated cases with pulmonary TB and IMR produces a high frequency of treatment failure and death due to tuberculosis. We recommend re-evaluating the optimal schedule for patients harboring IMR. It is necessary to strengthen scientific research for the evaluation of alternative treatment schedules in similar settings.

Primary ethambutol resistance among Iranian pulmonary tuberculosis patients: a systematic review

INTRODUCTION

Ethambutol (EMB) is an anti-mycobacterial agent that is most commonly used in combination with other anti-tuberculosis (TB) drugs in the treatment of TB. Studies have shown that primary resistance rates of Mycobacterium tuberculosis to EMB vary widely, that is, from 1% to as high as 14%. In this study, we aimed to determine the exact prevalence of primary EMB resistance among pulmonary TB cases.

METHODS

Several databases, including Medline, Embase, and Iranian databases, were searched from March 2000 to January 2016 to identify studies addressing EMB-resistant TB in Iran. Comprehensive meta-analysis (V2.2, Biostat) software was used to analyze the data.

RESULTS

Of the 112 records identified from the databases, 10 studies fulfilled the eligibility criteria. The pooled prevalence of primary EMB-resistant TB was estimated at 4.2% [95% confidence interval (CI) 1.8-9.0]. No evidence of publication bias was observed among the included studies (p = 0.4 for Begg rank correlation analysis; p = 0.2 for Egger weighted regression analysis).

CONCLUSION

Results of systematic review and meta-analyses indicated that effective strategies to minimize the acquired drug resistance, to improve the drug susceptibility testing (DST) capability, and to control the transmission of resistance should be attached importance for control of TB in Iran.

First-Line Anti-Tubercular Drug Resistance of Mycobacterium tuberculosis in IRAN: A Systematic Review

BACKGROUND

The spread of drug-resistant tuberculosis (TB) is one of the major public health problems through the world. Surveillance of anti-TB drug resistance is essential for monitoring of TB control strategies. The occurrence of drug resistance, particularly multi-drug resistance Mycobacterium tuberculosis (MDR), defined as resistance to at least rifampicin (RIF) and isoniazid (INH), has become a significant public health dilemma. The status of drug-resistance TB in Iran, one of the eastern Mediterranean countries locating between Azerbaijan and Armenia and high-TB burden countries (such as Afghanistan and Pakistan) has been reported inconsistently. Therefore, the aim of this study was to summarize reports of first-line anti-tubercular drug resistance in M. tuberculosis in Iran.

MATERIAL AND METHODS

We systematically reviewed published studies on drug-resistant M. tuberculosis in Iran. The search terms were "Mycobacterium tuberculosis susceptibility" or "Mycobacterium tuberculosis resistant" and Iran.

RESULTS

Fifty-two eligible articles, published during 1998-2014, were included in this review. Most of the studies were conducted in Tehran. The most common used laboratory method for detecting M. tuberculosis drug resistant was Agar proportion. The highest resistance to first-line drugs was seen in Tehran, the capital city of Iran. The average prevalence of isoniazid (INH), rifampin (RIF), streptomycin (SM), and ethambotol (EMB) resistance via Agar proportion method in Tehran was 26, 23, 22.5, and 16%, respectively. In general, resistance to INH was more common than RIF, SM, and EMB in Tehran Conclusions: In conclusion, this systematic review summarized the prevalence and distribution of first-line anti-tubercular drug resistance of M. tuberculosis in Iran. Our results suggested that effective strategies to minimize the acquired drug resistance, to control the transmission of resistance and improve the diagnosis measures for TB control in Iran.

Rapid Molecular Detection of Multidrug-Resistant Tuberculosis by PCR-Nucleic Acid Lateral Flow Immunoassay

Several existing molecular tests for multidrug-resistant tuberculosis (MDR-TB) are limited by complexity and cost, hindering their widespread application. The objective of this proof of concept study was to develop a simple Nucleic Acid Lateral Flow (NALF) immunoassay as a potential diagnostic alternative, to complement conventional PCR, for the rapid molecular detection of MDR-TB. The NALF device was designed using antibodies for the indirect detection of labeled PCR amplification products. Multiplex PCR was optimized to permit the simultaneous detection of the drug resistant determining mutations in the 81-bp hot spot region of the rpoB gene (rifampicin resistance), while semi-nested PCR was optimized for the S315T mutation detection in the katG gene (isoniazid resistance). The amplification process additionally targeted a conserved region of the genes as Mycobacterium tuberculosis (Mtb) DNA control. The optimized conditions were validated with the H37Rv wild-type (WT) Mtb isolate and Mtb isolates with known mutations (MT) within the rpoB and katG genes. Results indicate the correct identification of WT (drug susceptible) and MT (drug resistant) Mtb isolates, with the least limit of detection (LOD) being 10⁴ genomic copies per PCR reaction. NALF is a simple, rapid and low-cost device suitable for low resource settings where conventional PCR is already employed on a regular basis. Moreover, the use of antibody-based NALF to target primer-labels, without the requirement for DNA hybridization, renders the device generic, which could easily be adapted for the molecular diagnosis of other infectious and non-infectious diseases requiring nucleic acid detection.

MDR-TB Antibody Response (Western Blot) to Fractions of Isoniazid and Rifampicin Resistant Antigens of Mycobacterium tuberculosis

Drug-resistant TB poses a major threat to control of TB worldwide. Despite progress in the detection of Multidrug-resistant TB (MDR-TB) cases, a major diagnostic gap remains: 55% of reported TB patients estimated to have MDR-TB were not detected in 2013. MDR-TB antigens were conjugated to CNBr-activated Sepharose 4B. Specific polyclonal antibodies against MDR-TB Ags were prepared in rabbits using two boosted injections of the MDR-TB antigen. The antibodies were purified and treated with susceptible TB to remove any non-specific and cross-reactive antibodies. In the present study, comparative analysis of electrophoretic pattern of different antigens of INH/RIF-resistant TB were studied for identifying protein profiles. A RIF-resistant TB antigen was shown here to have different protein profiles from INH-resistant TB isolate. The results of Western blotting analysis showed that in the RIF- and INH-resistant antigenic fractions some bands of 14.4 and 45 kDa as immunogenic were common. Moreover, four bands of RIF-resistant TB antigen fractions (16, 19, 21, and 45 KDa) and one band of INH-resistant TB (about 26 KDa) were detected as diagnostic antigens. This study suggests that the Western blot is an accurate test to survey INH- and RIF-resistant TB antigens of M. tuberculosis infection. These findings indicate that MDR-TB diagnosis (based on Ag detection) could be useful in the identification of disease stages that precede symptomatic and microbiologically positive TB, such as subclinical and incipient TB.

Novel katG mutations causing isoniazid resistance in clinical M. tuberculosis isolates

We report the discovery and confirmation of 23 novel mutations with previously undocumented role in isoniazid (INH) drug resistance, in catalase-peroxidase (katG) gene of Mycobacterium tuberculosis (Mtb) isolates. With these mutations, a synonymous mutation in fabG1^g609a, and two canonical mutations, we were able to explain 98% of the phenotypic resistance observed in 366 clinical Mtb isolates collected from four high tuberculosis (TB)-burden countries: India, Moldova, Philippines, and South Africa. We conducted overlapping targeted and whole-genome sequencing for variant discovery in all clinical isolates with a variety of INH-resistant phenotypes. Our analysis showed that just two canonical mutations (katG 315AGC-ACC and inhA promoter-15C-T) identified 89.5% of resistance phenotypes in our collection. Inclusion of the 23 novel mutations reported here, and the previously documented point mutation in fabG1, increased the sensitivity of these mutations as markers of INH resistance to 98%. Only six (2%) of the 332 resistant isolates in our collection did not harbor one or more of these mutations. The third most prevalent substitution, at inhA promoter position -8, present in 39 resistant isolates, was of no diagnostic significance since it always co-occurred with katG 315. 79% of our isolates harboring novel mutations belong to genetic group 1 indicating a higher tendency for this group to go down an uncommon evolutionary path and evade molecular diagnostics. The results of this study contribute to our understanding of the mechanisms of INH resistance in Mtb isolates that lack the canonical mutations and could improve the sensitivity of next generation molecular diagnostics.

First Outcome of MDR-TB among Co-Infected HIV/TB Patients from South-West Iran

Background

Tuberculosis (TB) is the leading cause of mortality among human immunodeficiency virus (HIV) patients and the majority of them occur in developing countries. The aims of the present study were to determine the frequency of HIV/TB co-infection and other probable associated factors.

Methods

This 10 year retrospective study was conducted on 824 HIV patients in the south-west of Iran. HIV infection was diagnosed by the enzyme linked immunosorbent assay and confirmed by Western blot. TB diagnosis was based on consistency of the clinical manifestations, chest X-ray, and microscopic examination. Drug susceptibility testing was done by the proportional method on Löwenstein-Jensen media.

Results

Of 824 HIV patients, 59 (7.2%) were identified as TB co-infected and the majority (86.4%) of them were male. Of the overall TB infected patients, 6 cases (10.2%) showed multidrug-resistant with the mean CD4+ lymphocyte count of 163±166 cells/mm³. The main clinical forms of TB were pulmonary (73%). There was a significant (p<0.05) correlation between TB infection and CD4+ lymphocyte counts ≤200 cells/mm³, gender, prison history, addiction history, and highly active anti-retroviral therapy.

Conclusion

We reported novel information on frequency of HIV/TB co-infection and multidrug resistant-TB outcome among co-infected patients that could facilitate better management of such infections on a global scale.