Effects of non-tuberculous mycobacteria on BCG vaccine efficacy: A narrative review.

The Mycobacterium tuberculosis bacterial pathogen is responsible for the ongoing global tuberculosis (TB) epidemic. Bacille Calmette-Guérin (BCG), the only currently approved TB vaccine, is successful in preventing disseminated disease in newborns. However, it has a variable efficacy against pulmonary TB in adults. This protective effect of the vaccine varies greatly among different populations and geographical areas, which the increased exposure of particular populations to non-tuberculous mycobacteria (NTM) is considered as one of the reasons for this issue. Numerous studies have shown that exposure to NTM species causes the host immune system to be improperly primed. It has also been suggested that NTM species may be blamed for reduction in BCG vaccine effectiveness against M. tuberculosis. The increased exposure of certain populations to NTM has diverse effects on BCG efficacy. Moreover, the exposure to NTM can induce opposite effects on BCG efficacy depending on the NTM exposure route and survivability. A detailed understanding of the impact of NTM exposure on the efficacy of the BCG vaccine is essential for ongoing efforts to develop new TB vaccines as it may ultimately be a crucial success factor. The aim of this study was to review the findings of the studies focusing on the effects of NTM on BCG vaccine efficacy in animal models.

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.

Antibacterial activity of chitosan-based nanohybrid membranes against drug-resistant bacterial isolates from burn wound infections.

Biocompatible and non-toxic properties of chitosan make it a candidate with excellent application prospects in developing wound dressing conjugate compounds. Six different chitosan-based nanohybrid membranes were evaluated against multidrug-resistant bacterial isolates. Different combinations of chitosan, ciprofloxacin (CIP), biofunctionalized montmorillonite (MMT), and montmorillonite with sulfate chains (SMMT) were provided, and their antibacterial activity was assessed using the colony count method. Totally, 27 drug-resistant isolates, including 6x methicillin-resistant Staphylococcus aureus, 7 vancomycin-resistant Enterococcus faecalis, 4 Acinetobacter baumannii, and 10 Pseudomonas aeruginosa isolates were identified from burn wound infections. Chitosan and montmorillonite did not show significant antibacterial effect (p > 0.05), but chitosan/SMMT/CIP was the most effective nanocomposite (p < 0.01). Chitosan-based nanocomposites with ciprofloxacin could effectively reduce the susceptibility of drug-resistant bacterial isolates. Bacterial targeting using nanosystems provides an opportunity for effective antibiotic treatment by improving antibacterial efficacy.

Bacterial community of chronic rhinosinusitis patients and therapeutic ultrasound efficacy: clinical trial study.

Background and Objectives: Bacterial involvement in chronic rhinosinusitis (CRS) condition made it difficult to treat using available antibiotic therapy. Therapeutic ultrasound was investigated here to evaluate bacterial diversity and quantity before and after continuous/pulsed ultrasound strategy compared to control patients. Materials and Methods: Totally, 34 CRS patients were studied in three groups, including continuous ultrasound, pulsed ultrasound and control. Bacterial culture and identification were done before and after treatment. Computed tomography scan (CT scan) and questionnaire scores were recorded two times before and after intervention. Results: The most prevalent bacterial isolates were non-hemolytic Streptococci (34 patients), coagulase-negative Staphylococcus (33 patients), Gram-negative cocci (26 patients), Staphylococcus aureus (19 patients), Streptococcus pneumoniae (five patients) and Streptococcus pyogenes (five patients). Both continuous and pulsed ultrasound could significantly reduce the quantity of bacterial isolates after treatment. CT scan and questionnaire results support the effectiveness of therapeutic ultrasound. Conclusion: The quantity of clinically important bacteria was significantly reduced using ultrasound treatment and recovery of patients was supported by CT scan and questionnaire scores. Alternative therapeutic ultrasound could be an effective procedure in CRS patients.

The 7H11 Agar Medium Supplemented with Calf Bovine Serum for Susceptibility Testing of Mycobacterium tuberculosis Isolates Against Pyrazinamide.

Despite its importance, pyrazinamide (PZA) is a blind spot in drug susceptibility testing in tuberculosis laboratories. The aim of this study was to set up a reliable agar-based proportion method for detection of PZA-resistant phenotypes using Middlebrook 7H11 agar supplemented with calf bovine serum (CBS) compared with albumin/dextrose/catalase (ADC) enrichment and pncA/rpsA sequencing results. The 7H11 agar medium supplemented with 10% ADC or 10% CBS (pH 6.2) and 100 µg/mL PZA was used to detect PZA resistance among 64 Mycobacterium tuberculosis isolates. Sanger sequencing and whole-genome sequencing were performed to track mutations in the pncA, rpsA, and their upstream regions. A total of 43 rifampicin/multidrug-resistant, 20 drug-susceptible, and 1 isoniazid mono-resistant M. tuberculosis isolates were investigated. The 7H11+ADC and 7H11+CBS could detect 22 and 23 PZA-resistant strains, respectively. With the same specificity, the sensitivity and accuracy of 7H11+CBS was found to be a little greater than 7H11+ADC in PZA resistance detection compared with sequencing results. Twenty-four mutant strains were found to have different mutations in pncA-upstream, pncA and rpsA genes, in which Gly97Asp was the most dominant mutation. The results obtained from 7H11+CBS were comparable to the results of 7H11+ADC. Therefore, the 7H11 agar proportion method would be a less-expensive test using CBS and produces reliable results.

Assessment of the GenoType MTBDRsl VER 2.0 compared to the phenotypic drug susceptibility testing and whole genome sequencing for the rapid detection of resistance to fluoroquinolone and second-line injectable drugs among rifampicin-resistant Mycobacterium tuberculosis isolates.

Molecular techniques have considerable advantages for rapid detection, a reduction of infectiousness, prevention of further resistance development and surveillance of drug-resistant TB. MTBDRsl VER 2.0 was used to detect resistance to second-line anti-tuberculosis drugs on 35 rifampicin-resistant M. tuberculosis (RR-MTB) isolates compared to the minimum inhibitory concentrations (MICs) and whole genome sequencing (WGS). The MTBDRsl VER 2.0 (Hain Life Science, Nehren, Germany) and WGS (San Diego, CA, USA) were performed for tracing mutations in resistant-related genes involved in resistance to fluoroquinolone (FLQ) and second-line injectable drugs. The broth microdilution method using 7H9 Middlebrook media supplemented with OADC was used to determine the MICs. The MTBDRsl VER 2.0 correctly detected 5/6 (83.3%) of FLQ-resistant strains. The MUT1 A1401G (seven strains) and MUT2 G1484T (one strain) mutations in rrs gene were detected in eight AMK/KAN/CAP-resistant strains. Four low-level KAN-resistant strains with the G-10A/C-12T (three strains) and eis C-14T (one strain) mutations in eis gene was diagnosed using MTBDRsl VER 2.0. Five errors were found in detecting resistance to kanamycin and capreomycin compared to the phenotypic drug susceptibility testing and WGS. Failling wild-type bands without improved mutant bands did not indicate a reliable resistance. WGS could efficiently resolve the discrepancies of the results. MTBDRsl showed better performance in detecting XDR strains than pre-XDR.

Comparison of toxin-antitoxin expression among drug-susceptible and drug-resistant clinical isolates of Mycobacterium tuberculosis.

INTRODUCTION: Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB), is a significant global public health threat. Besides extensive multidrug resistance, MTB possesses several properties for long-term viability in the host as well as stress adaptation and resistance in harsh conditions. The role of toxin-antitoxin (TA) systems in disseminating and maintaining antimicrobial resistance in bacterial populations has also been demonstrated. This study aimed to evaluate differences in expression of MazEF (a well-known TA system) related genes (mazE3, mazF3, mazE6, and mazF6) amongst drug-susceptible and resistant MTB isolates in Iran. MATERIAL AND METHODS: A total of 20 confirmed clinical isolates of MTB including 10 drug-susceptible and 10 drug-resistant (nine MDR, and one XDR) species were included in this study. M. tuberculosis H37Rv was used as the standard strain. RNA extraction, cDNA synthesis, and relative quantitative real-time PCR were performed according to the standard procedures. RESULTS: Our analysis indicated significant enhanced expression of the mazE6 antitoxin gene in drug-susceptible isolates compared to drug-resistant isolates and the standard strain. The expression of the mazF6 toxin gene was also increased in drug-susceptible isolates compared with the standard strain. In drug-resistant isolates, the expression levels of mazF3 and mazF6 genes were significantly higher than that in the susceptible isolates and the standard strain. CONCLUSIONS: In this study, there was significant overexpression of mazE6 in drug-susceptible isolates. As well, mazF3 and F6 were overexpressed in drug-resistant isolates when compared with the standard strain. The changes in expression levels of MazEF6 associated genes were greater than that of MazEF3 in both groups of isolates.

Genotyping and Drug Susceptibility Patterns of M. Tuberculosis Isolated from HIV Seropositive Patients in Tehran Iran.

AIM: This study aims to investigate the prevalence and drug-resistance M. tuberculosis isolated from HIV seropositive individuals in Tehran, Iran. BACKGROUND: Human immunodeficiency virus (HIV) is one of the most important risk factors for developing active tuberculosis (TB). OBJECTIVE: The objective is to determine the rate of transmission and drug-resistant M. tuberculosis (MTB) strains isolated from HIV seropositive patients in Tehran province, Iran. METHODS: This study consecutively enrolled 217 TB/HIV coinfected patients from April 2018 to August 2019 at Emam Khomeini referral hospital and 5 other health centers in Tehran province. The isolates were genotyped using 15 loci Mycobacterial interspersed repetitive unit-variable number tandem repeats (MIRU-VNTR). Minimum inhibitory concentration (MIC) was determined for 6 drugs. In addition, mutations were assessed in rpoB, katG, inhA, and ahpC genes using Reverse Blot Hybridization Assay System. RESULTS: A 20 (9.2%) patients were culture-positive for M. tuberculosis and typed by MIRU-VNTR, 13 (65%) strains formed 5 clusters, but 6 (30%) isolates had a unique pattern. The total Hunter- Gaston discrimination index (HGDI) for all 15 loci was 0.846, and the cluster size was 2 to 4 patients. The estimated proportion of recent transmission was 45%. The mutation was identified in 1 isolate, lost inhAW1 and mutation in MT1 loci, which was resistant to isoniazid (INH). Moreover, 1 (5%) and 3 (15%) isolates were resistant to INH and ethambutol (EMB), respectively, of which 1 was resistant to INH and EMB. CONCLUSION: The transmission rate of TB in HIV patients was relatively high; however, the prevalence of drug-resistant strains and TB infection in females was insignificant in this study (p < 0.05); none of the isolates was MDR strains.

Incidence, Clinical Manifestation, Treatment Outcome, and Drug Susceptibility Pattern of Nontuberculous Mycobacteria in HIV Patients in Tehran, Iran.

BACKGROUND: Nontuberculous mycobacterial (NTM) infections have radically increased worldwide due to the increase in HIV infections. The disease activity increases with progressive immunodeficiency. METHODS: A total of 216 HIV seropositive patients suspected of having mycobacterial infection were recruited for this study. Clinical samples were collected from each patient and cultured on Lowenstein-Jensen media. Detection and species identification were simultaneously done using Reverse Blot Hybridization Assay System. Also, the minimum inhibitory concentrations (MIC) for each isolate were determined in 7H9 broth media for 10 antibiotics. RESULTS: In this study, 4 rapid and 4 slow-growing NTM species were isolated and identified. Mycobacterium fortuitum was the most common NTM species, 3/8 (37.5%), followed by Mycobacterium kansasii, 2/8 (25%). The cases were identified as pulmonary disease, 5/8 (62.5 %), disseminated infection, 2/8 (25%), and skin abscess, 1/8 (12.5%). M. chelonae and Mycobacterium avium were isolated from patients diagnosed with disseminated infection with treatment failure. The skin abscess was caused by infection with M. simiae. The results of the MIC testing were as follows: M. kansasii and M. fortuitum were susceptible to amikacin (AMK); M. avium to clarithromycin (CLA); M. fortuitum 2/3 (67%) to ciprofloxacin (CIP); 1/2 (50%) of M. kansasii isolates to CLA, and M. chelonae to rifampin (RIF), linezolid (LIN), AMK, and CIP at medium and high concentrations. CONCLUSION: AMK showed incredible in vitro activity against M. kansasii and M. fortuitum. Also, M. avium was susceptible to CLA, whereas M. simiae and M. chelonae were resistant to the tested drugs in this study.

Whole Genome Sequencing Results Associated with Minimum Inhibitory Concentrations of 14 Anti-Tuberculosis Drugs among Rifampicin-Resistant Isolates of Mycobacterium Tuberculosis from Iran.

Accurate and timely detection of drug resistance can minimize the risk of further resistance development and lead to effective treatment. The aim of this study was to determine the resistance to first/second-line anti-tuberculosis drugs in rifampicin/multidrug-resistant Mycobacterium tuberculosis (RR/MDR-MTB) isolates. Molecular epidemiology of strains was determined using whole genome sequencing (WGS)-based genotyping. A total of 35 RR/MDR-MTB isolates were subjected to drug susceptibility testing against first/second-line drugs using 7H9 Middlebrook in broth microdilution method. Illumina technology was used for paired-end WGS applying a Maxwell 16 Cell DNA Purification kit and the NextSeq platform. Data analysis and single nucleotide polymorphism calling were performed using MTBseq pipeline. The genome-based resistance to each drug among the resistant phenotypes was as follows: rifampicin (97.1%), isoniazid (96.6%), ethambutol (100%), levofloxacin (83.3%), moxifloxacin (83.3%), amikacin (100%), kanamycin (100%), capreomycin (100%), prothionamide (100%), D-cycloserine (11.1%), clofazimine (20%), bedaquiline (0.0%), and delamanid (44.4%). There was no linezolid-resistant phenotype, and a bedaquiline-resistant strain was wild type for related genes. The Beijing, Euro-American, and Delhi-CAS were the most populated lineage/sublineages. Drug resistance-associated mutations were mostly linked to minimum inhibitory concentration results. However, the role of well-known drug-resistant genes for D-cycloserine, clofazimine, bedaquiline, and delamanid was found to be more controversial.

Molecular identification of mutations conferring resistance to rifampin, isoniazid and pyrazinamide among Mycobacterium tuberculosis isolates from Iran.

Here, we aimed to determine the susceptibility of 70 Mycobacterium tuberculosis isolates obtained from different regions of the country to 8 anti-tuberculosis (anti-TB) drugs and possible underlying mechanisms causing resistance to rifampin, isoniazid, and pyrazinamide. The susceptibility of 70 isolates of M. tuberculosis to anti-TB drugs was tested using proportion method. Strains showing resistance to the first line anti-TB drugs were subjected to PCR amplification and sequencing of the rpoB, katG, ahpC, pncA genes, inhA promoter and oxyR-ahpC intergenic regions to detect resistance conferring mutations. Overall, 77.1% and 77.1% of isolates were resistant to at least one of the tested first- and second-line drugs, respectively. Within the rpoB gene the highest rate of mutation was found in codons 531(450) (56.3%), and 533(452) (12.5%). Also, codons 315 (42.4%) of katG, positions -48, -72 and -77 of oxyR-ahpC (total= 3, 9.1%) and -15 of inhA promoter region (33.3%) were the most altered positions in isoniazid resistant isolates. Only a single mutation was detected for pncA among resistant isolates. High prevalence of resistance to essential anti-TB drugs among M. tuberculosis strains isolated from retreated tuberculosis cases is alarming issue necessitating immediate action to prevent the spread of drug resistant isolates in the country.

The Chemical Composition and Anti-mycobacterial Activities of Trachyspermum copticum and Pelargonium graveolens Essential Oils.

BACKGROUND: Microbial resistance to antibiotics and their adverse effects related to these antibiotics are a matter of global public health in the 21th century. The emergence of drug-resistant strains, has gained the interest of the scientists to discover new antimicrobial agents from the essential oil of medicinal plants. METHODS: Anti-mycobacterial effects of Trachyspermum copticum and Pelargonium graveolens essential oils were determined against multi-drug resistant clinical strains of Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium fortuitum and standard strain of Mycobacterium tuberculosis H37Rv by a Broth micro-dilution method. Pelargonium graveolens plant named Narmada was discovered by Kulkarni R.N et al. (Patent ID, USPP12425P2) and a formulation comprising thymol obtained from Trachyspermum is useful in the treatment of drug-resistant bacterial infections (Patent ID, US6824795B2). The chemical composition of hydro-distilled essential oils was determined by GC and GC-MS. RESULTS: Minimum Inhibitory Concentration (MIC) values for T. copticum essential oil against tested isolates were ranged from 19.5 µg/mL to 78 µg/mL. The least minimum inhibitory concentration of P. graveolens extract against M. Kansasii and MDR-TB was 78 µg/ml. CONCLUSION: The results of the present research introduced T. copticum and P. graveolens essential oils as a remarkable natural anti-mycobacterial agent, but more pharmacological studies are required to evaluate their efficacy in animal models.

Efficacy Of Line Probe Assay In Detection Of Drug-Resistant Pulmonary Tuberculosis In Comparison With GeneXpert And Phenotypic Methods In Iran And Genetic Analysis Of Isolates By MIRU-VNTR.

BACKGROUND: Successful treatment of tuberculosis depends on early diagnosis and use of appropriate drug susceptibility testing in a timely manner. In the present study, LPA efficacy was assayed in detection and drug susceptibility testing of pulmonary tuberculosis in comparison to available methods in Iran and phylogenetic analyses of isolated cases carried out by MIRU-VNTR. METHODS: This study was conducted at the Tehran Regional Reference Laboratory for Tuberculosis. All sputum specimens were subjected to smear, culture, and drug susceptibility testing (DST), GeneXpert, and LPA. Finally, 15-locus-based MIRU-VNTR was used for molecular genotyping. RESULTS: From a total of 920 sputum specimens, 6.08% (n=56) were identified as MTBC by culture, 6.8% (n=63) by GeneXpert, and 6.5% (n=60) by LPA. Phenotype DST and LPA methods confirmed the resistance of 4 and 14 specimens to rifampin (RIF) and isoniazid (INH); two cases were considered as multidrug-resistant (MDR). Using GeneXpert, four cases were identified as RIF-resistant. Based on LPA results, inhA and katG mutations were detected in 100% and 21.4% of INH-resistant cases, respectively. All 56 culture positive Mycobacterium tuberculosis isolates were placed in 29 different clusters using MIRU-VNTR genotyping. Two MDR-TB, 2 RIF mono-resistant, and 12 INH mono-resistant cases were placed in different clusters. CONCLUSION: LPA is an appropriate method for early detection and accurate diagnosis of TB and drug-resistant cases that makes it possible to distinguish INH mono-resistant cases from MDR cases in Iran.

Detection of Nocardia, Streptomyces and Rhodococcus from bronchoalveolar lavage specimens of patients with HIV by Multiplex PCR Assay.

BACKGROUND: Nocardia, Streptomyces and Rhodococcus are life threatening opportunistic pathogens under immunodeficiency conditions, particularly among patients infected with HIV. Rapid and accurate detection of these infections can improve immune health quality, patient management and appropriate treatment. The aim of this study was to design a novel multiplex-PCR assay for rapid diagnosis of these three organisms directly from bronchoalveolar lavage (BAL) specimens of patients infected with HIV. METHODS: The genus specific primers were designed for direct-detection of Nocardia, Streptomyces and Rhodococcus in a single tube multiplex PCR. This PCR specifically amplified the target genes from pure cultures. It subsequently was applied on BAL specimens of 29 HIV positive patients that had previously been culture negative for actinomycete bacteria, of which Nocardia, Streptomyces and Rhodococcus are members. RESULTS: Of 29 respiratory clinical specimens, there were positive for Nocardia spp. and one was positive for Streptomyces spp using the multiplex PCR assay. The sequencing of the PCR products identified the species as Nocardia cyriacigeorgica (n=2), Nocardia farcinica and Streptomyces albus. CONCLUSION: This novel multiplex PCR assay yielded reliable results for accurate identification of Nocardia, Streptomyces and Rhodococcus from BAL while the results of bacterial culture were negative.

The pulsed ultrasound strategy effectively decreases the S. aureus population of chronic rhinosinusitis patients.

OBJECTIVE: Staphylococcus aureus with the ability of biofilm formation and the drug resistance acquisition is one of the most frequently isolated pathogens from chronic rhinosinusitis patients. Ultrasound as an alternative therapy is effectively able to kill the bacteria by cavitation in or on the bacterial cells and peroxide generation and hence improving antibiotic treatment efficacy. RESULTS: Staphylococcus aureus was detected in 4 and 6 out of 14 patients by phenotypic and qPCR assays, respectively. Four patients were completely resolved after pulsed ultrasound treatment. However, presence of the S. aureus was confirmed in three healthy controls by bacterial cultivation. Pulsed ultrasound have been quantitatively decreased the S. aureus population in chronic rhinosinusitis patients (p < 0.05). Further studies need to be investigated the effectiveness of pulsed ultrasound as an alternative course of CRS patient's treatment.

Molecular characterization of multidrug and extensive drug-resistant Mycobacterium tuberculosis isolates from Iran.

Tuberculosis (TB) is one of the main causes of death among curable infectious diseases and one of the top 10 causes of death worldwide. Hence, molecular typing of MTB strains is necessary for epidemiological studies and helps to identify risk factors for TB transmission. Therefore, the present study was conducted to determine molecular typing of drug-resistant M. tuberculosis strains isolated from Iran using the RFLP-PGRS method. Thirty-two MDR strains and one XDR strain were isolated from TB patients in four major cities of Iran. MTB isolates were subjected to drug susceptibility testing. Whole genomic DNA from mycobacterial colonies were extracted and hybridized with PGRS probe in RFLP analysis. All fingerprinted MDR and XDR isolates were grouped into 13 clusters. The largest cluster (cluster 3) contained 48.4% (n = 16) of all isolates. Clusters 1, 4, and 6 included 2, 4, and 2 isolates, respectively. Two isolates were in cluster 7, one was H37Rv standard strain, which was used as a control strain in this study, and eight isolates were placed in single clusters. This study provides information about molecular epidemiology of MDR-TB in Iran. The alarming increase in the incidence of MDR isolates, especially Beijing strains, raises concerns for TB control programs in Iran.

Resistance of Mycobacterium tuberculosis strains to Rifampicin: A systematic review and meta-analysis.

INTRODUCTION: Antitubercular drug resistance strain is a horrifying barrier to effective TB treatment and prevention. The present study aimed to determine the prevalence and geographical distribution of rifampicin-resistance M. tuberculosis (MTB) strains. METHODS: We searched two electronic databases, PubMed and EMBASE, until 26 March 2017 and updated our search on 27 April 2018 and accessed all prevalence studies of MTB strain and their drug susceptibility patterns to rifampicin. The pooled prevalence estimate was determined using random effects model. RESULTS: We identified 23 studies satisfying the inclusion criteria. The proportion of rifampicin resistance strains was diverged depending on the type of strains, country and Regions. The pooled estimate of rifampicin-resistance strains of MTB for the included studies was 4% (95% CI: 3-5%). In subgroup analysis based on World Health Organization (WHO) Regions, the pooled estimate of rifampicin-resistance strains of MTB was 11% (95% CI: 9-13%) with the Western Pacific Region 24%, Europian Region 10%, South-East Asian Region 6%, African Region 3% and Region of American 1%. Beijing family was the most dominant strain resistance to rifampicin with pooled prevalence of 14% (95% CI: 10-18%). The pooled prevalence of other families, i.e. EAI, T, CAS, MANU, Haarlem, LAM and Ural, was ≤2% for each. CONCLUSION: High burden of rifampicin resistance MTB strains was identified in the Western Pacific Region. Of these, Beijing family was predominantly resistance to rifampicin in Western Pacific Region and South-East Asian Region and also spread to European Region and Region of American.

Expression analysis of 10 efflux pump genes in multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis clinical isolates.

OBJECTIVES: Active extrusion of antituberculosis drugs via efflux pumps (EPs) has been suggested as contributing to drug resistance in Mycobacterium tuberculosis. This study was conducted to determine the role of 10 drug efflux transporters in the development of drug resistance in a series of clinical M. tuberculosis isolates. METHODS: A total of 31 clinical M. tuberculosis isolates without drug exposure [21 multi/extensively drug-resistant (M/XDR-TB) and 10 drug-susceptible isolates] were studied. The expression profile of 10 EP genes, including efpA, mmr, stp, drrA, drrB, mmpL7, Rv1250, Rv1634, Rv2994 and Rv1258c, was investigated against the H37Rv standard strain by quantitative reverse transcription PCR (RT-qPCR). RESULTS: Among the 21M/XDR-TB isolates, 10 showed significantly increased levels of gene expression (>4-fold) for at least one of the studied EPs. Moreover, of the isolates with overexpressed genes, three and seven lacked genetic alterations in the surveyed regions of the rpoB+katG+inhA and katG+inhA genes, respectively. Whilst no elevation was observed in the expression of mmr, Rv1250, Rv1634 and Rv1258c genes in any of the isolates, drrA, stp and drrB were found to be the most commonly overexpressed, being overexpressed in seven, five and three isolates, respectively. Decreased minimum inhibitory concentrations (MICs) of rifampicin, but not isoniazid, were observed in the presence of the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). CONCLUSION: Overexpression of EP genes can contribute to the emergence of a MDR phenotype in M. tuberculosis. Inhibition of EPs may provide a promising strategy for improving tuberculosis treatment outcomes in patients infected with M/XDR-TB isolates.

Molecular Epidemiology and Drug Resistance Pattern of Carbapenem-Resistant Klebsiella pneumoniae Isolates from Iran.

The emergence and dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates and their involvement in several nosocomial outbreaks are of high concern. This study was conducted to investigate the genetic relatedness and molecular determinants of carbapenem resistance in 100 CRKP isolates. Susceptibility to carbapenems as well as other antibiotics was determined by using disk diffusion method. The Modified Hodge test was performed for detection of carbapenemase production. The minimum inhibitory concentrations of selected antibiotics were determined by broth microdilution method. The presence of blaOXA-48, blaKPC, blaNDM, and blaVIM carbapenemase genes was examined by PCR, and clonal relatedness of CRKP isolates was investigated by pulsed-field gel electrophoresis (PFGE) analysis. blaOXA-48 was the most frequent carbapenemase gene (72%), followed by blaNDM (31%). None of the isolates harbored blaKPC and blaVIM genes. PFGE separated the majority of isolates into 10 clusters, including the major clusters A and B, carrying blaOXA-48, and clusters C and D, carrying blaNDM, and 4 isolates had a unique PFGE pattern. An increased rate of colistin resistance (50%) was detected among the isolates. Tigecycline was found to be the most active agent against CRKP isolates. Our results revealed that high prevalence of blaOXA-48 and blaNDM carbapenamses and resistance to colistin are alarming threats, necessitating an immediate action to prevent the spread of carbapenem-colistin-resistant K. pneumoniae isolates in Iran.

Quantitative analysis of Staphylococcus aureus in patients with chronic rhinosinusitis under continuous ultrasound treatment.

BACKGROUND AND OBJECTIVES: Bacterial pathogens, in particular drug resistant strains, involved in chronic rhinosinusitis may result in treatment failure. Ultrasound waves are able to destroy bacterial population in sinus cavities and can recover patients. MATERIALS AND METHODS: Twelve patients with chronic sinusitis and 10 healthy controls were treated by continuous ultrasound waves. Clinical specimens were collected before and after treatment. Serial diluted specimens were cultured on blood agar, chocolate and MacConkey agar plates for bacterial isolation. Bacterial DNA was extracted and used for Staphylococcus aureus detection using quantitative PCR. RESULTS: S. aureus was the most isolated bacterium (10 patients), which was eradicated from 8 patients after treatment. Using phenotypic methods at the beginning, 3 out of 10 healthy individuals were found to be positive. From 11 positive patients for S. aureus identified by real time qPCR, 9 showed significant reduction after treatment. In the healthy group, S. aureus was detected in 4 samples using qPCR, but they were clean at the second sampling. CONCLUSION: According to our phenotypic and molecular experiments, continuous ultrasound treatment effectively reduced the bacterial population in studied patients (p < 0.01). This was a hopeful basis for doing more studies with ultrasound therapy as a treatment option.