Prevalence of Non-Tuberculosis Mycobacterial Infections among Tuberculosis Suspects in Iran: Systematic Review and Meta-Analysis

Phylogenetic analysis of prevalent Mycobacterium species in Northeastern Iran based on hsp65 and tuf genes

Phylogenetic analysis of Mycobacterium species can provide valuable insights into their evolutionary relationships and help to identify species and strains. In this study, two genetic markers, including the heat shock protein 65 (hsp65) gene and the elongation factor (EF)-Tu (tuf) gene were used for phylogenetic analysis of Mycobacterium species. Clinical samples were collected from patients suspected of tuberculosis. Bacterial isolates were obtained from sputum samples and cultured on Löwenstein-Jensen medium. Thirty Mycobacterium isolates (acid-fast +, culture +), were included in our study. After DNA extraction, hsp65 (441 bp) and tuf (741 bp) genes were PCR-amplified and sequenced. The Neighbor-Joining method was employed to infer the evolutionary history of the isolates and the analyses were conducted with MEGA X software. The phylogenetic trees were validated using bootstrap analysis with 1000 replicates. Bootstrap values above 70 % considered indicative of well support for the branches. The phylogenetic trees revealed the overall natural relationships among Mycobacterium species. Our results demonstrated that the tuf gene provides superior resolution for identifying distinct mycobacterial species, closely aligning its phylogenetic profile with the hsp65 gene. However, neither of the markers was effective in distinguishing members of the Mycobacterium tuberculosis complex (MTBC). This study highlights the high discriminatory power of the tuf gene, recommending its use as a primary genomic marker for phylogenetic analysis.

Species and genetic diversity of nontuberculous mycobacteria in suspected tuberculosis cases in East Azerbaijan, Iran: a cross-sectional analysis

Introduction

The incidence of nontuberculous mycobacterial (NTM) infections has increased worldwide, attracting attention in routine diagnostic settings, particularly among patients with suspected tuberculosis. This study aimed to acquire knowledge of NTM infections in patients with suspected tuberculosis and to evaluate the genetic diversity of the strains.

Methods

In this study, 230 clinical specimens were collected from suspected tuberculosis patients. Following decontamination with N-Acetyl-L-cysteine-sodium hydroxide (NALC-NaOH), the sediments of specimens were inoculated onto Löwenstein-Jensen medium and then incubated at 37°C for 8 weeks. The samples that yielded positive cultures were evaluated through the sequencing of conserved fragments of IS6110 and hsp65. For those samples that were not identified as part of the M. tuberculosis complex (MTC) by IS6110 PCR, further analysis was conducted via PCR to detect fragments of the hsp65 gene.

Results

Twenty-one NTM species were isolated from 230 clinical specimens (14 NTM from pulmonary specimens and 7 from extrapulmonary specimens). Among these, 12 (57.14%) were rapid-growing mycobacteria (RGM), and 9 (42.85%) were slow-growing mycobacteria (SGM). No M. avium complex (MAC) was identified in any of the specimens. Notably, the M. kansasii, M. gordonae, and M. abscessus strains presented significant genetic diversity.

Conclusions

The prevalence of infections attributed to nontuberculous species surpasses that attributed to tuberculosis. These findings underscore the importance of exploring NTM species in individuals suspected of having TB.

Polycationic phosphorous dendrimer potentiates multiple antibiotics against drug-resistant mycobacterial pathogens

Mycobacterium tuberculosis (Mtb), causative agent of tuberculosis (TB) and non-tubercular mycobacterial (NTM) pathogens such as Mycobacterium abscessus are one of the most critical concerns worldwide due to increased drug-resistance resulting in increased morbidity and mortality. Therefore, focusing on developing novel therapeutics to minimize the treatment period and reducing the burden of drug-resistant Mtb and NTM infections are an urgent and pressing need. In our previous study, we identified anti-mycobacterial activity of orally bioavailable, non-cytotoxic, polycationic phosphorus dendrimer 2G0 against Mtb. In this study, we report ability of 2G0 to potentiate activity of multiple classes of antibiotics against drug-resistant mycobacterial strains. The observed synergy was confirmed using time-kill kinetics and revealed significantly potent activity of the combinations as compared to individual drugs alone. More importantly, no re-growth was observed in any tested combination. The identified combinations were further confirmed in intra-cellular killing assay as well as murine model of NTM infection, where 2G0 potentiated the activity of all tested antibiotics significantly better than individual drugs. Taken together, this nanoparticle with intrinsic antimycobacterial properties has the potential to represents an alternate drug candidate and/or a novel delivery agent for antibiotics of choice for enhancing the treatment of drug-resistant mycobacterial pathogens.

Global Epidemiology of Nontuberculous Mycobacterial Pulmonary Disease: A Review

Nontuberculous mycobacterial (NTM) isolation and pulmonary disease (NTM-PD) have continued to increase in most regions of the world, driven mainly by Mycobacterium avium. Single-center studies also support increasing trends as well as a persistent burden of undiagnosed NTM among persons suspected of having tuberculosis (TB), in countries with moderate-to-high TB prevalence. Cumulative exposure to water and soil presents an increased risk to susceptible hosts, and trace metals in water supply are recently recognized risk factors. Establishing standard case definitions for subnational and national surveillance systems with mandatory notification of NTM-PD are needed to allow comparisons within and across countries and regions.

Trends in the Antibiotic Resistance of Non-Tuberculous Mycobacteria in Iran: A Systematic Review and Meta-Analysis

Background

Non-tuberculous mycobacteria (NTM) infections have been continuously increasing as major concerns of public health in Iran. Because innate resistance of NTM species, the treatment of these infections is difficult task, but until now resistance pattern of NTM and suitable regimens are not determined.

Methods

We systematically searched the relevant studies in PubMed, Scopus, and Embase (Until Dec 2022). All statistical analyses were carried out using the statistical package R.

Results

Eleven studies included in the analysis were performed in 6 provinces and investigated 1223 NTM clinical species. The majority of the studies originated in Tehran. Among the first-line anti-TB drugs, almost all NTM species were highly resistant to first-line anti-TB drugs. No significant difference in the isoniazid resistance rate was found in the slow or rapid-growing species and Runyon's classification of NTM isolates. A decreased in the prevalence of ciprofloxacin, clarithromycin, and moxifloxacin resistance were showed in during 2013-2022 years.

Conclusion

Most investigated antibiotics have a minor effect on NTM species and a steady increase of resistance has been seen in last few years then, need more-effective alternative regimens is clear.

Global prevalence and genotype distribution of Microsporidia spp. in various consumables: a systematic review and meta-analysis

Water and food sources play a major role in the distribution and transfer of microsporidia infection to animals and humans. So, this systematic review and meta-analysis aimed to assess the status and genetic diversity of microsporidia infection in water, vegetables, fruits, milk, cheese, and meat. The standard protocol of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines was followed. Scopus, PubMed, Web of Science, and Google Scholar were searched from 1 January 2000 and 1 February 2023. The point estimates and 95% confidence intervals (CIs) were calculated using a random-effects model. Of the 1,308 retrieved studies, 35 articles were included in the final meta-analysis. The pooled prevalence of microsporidia infection in mixed water, mixed fruits, mixed vegetables, and milk was 43.3% (95% CI, 33-54.2%; I², 94.86%), 35.8% (95% CI, 5.3-84.8%; I², 0), 12% (95% CI, 4.9-26.6%; I², 96.43%), and 5.8% (95% CI, 2.7-12%; I², 83.72%), respectively. Considering the genotypes, microsporidia with genotype D in water sources and genotype CD6 in vegetables/fruits were the highest reported genotypes. Given the relatively high prevalence of microsporidiosis (especially in water sources), designing strategies for control, and prevention of microsporidia infection in these sources should be recommended.

Molecular epidemiology of nontuberculous mycobacteria isolated from tuberculosis-suspected patients

It is a growing problem around the world to deal with nontuberculous mycobacteria infection (NTM), but its clinical significance is still largely unknown. This study aims to investigate the epidemiology of NTM infections from various clinical samples and determine their clinical significance. From December 2020 to December 2021, 6125 clinical samples were collected. In addition to phenotypic detection, genotypic detection through multilocus sequence typing (hsp65, rpoB, and 16S rDNA genes) and sequencing was also conducted. Records of patients were consulted for clinical information, such as symptoms and radiological findings. Of the 6,125 patients, 351 (5.7%) were positive for acid-fast bacteria (AFB). Out of 351 AFB, 289 (82.3%) and 62 (17.7%) subjects were identified as M. tuberculosis complex (MTC) and NTM strains, respectively. Isolates of Mycobacterium simiae and M. fortuitum were the most frequent, followed by isolates of M. kansasii and M. marinum. We also isolated M. chelonae, M. canariasense, and M. jacuzzii, which are rarely reported. Symptoms (P = 0.048), radiographic findings (P = 0.013), and gender (P = 0.039) were associated with NTM isolates. M. Fortuitum, M. simiae, and M. kansasii presented with bronchiectasis, infiltration, and cavitary lesions most frequently, while cough was the most common symptom. In conclusion, Mycobacterium simiae and M. fortuitum were presented in seventeen and twelve NTM isolates from the collected samples. There is evidence that NTM infections in endemic settings may contribute to the dissemination of various diseases and the control of tuberculosis. In spite of this, further research is needed to evaluate the clinical significance of NTM isolates.

Drug resistance profiles and related gene mutations in slow-growing non-tuberculous mycobacteria isolated in regional tuberculosis reference laboratories of Iran: a three year cross-sectional study

There are limited studies on the antibiotic resistance patterns of slowly growing mycobacteria (SGM) species and their related gene mutations in Iran. This study aimed to elucidate the antibiotic susceptibility profiles and the mutations in some genes that are associated with the antibiotic resistance among SGM isolates from Iran. The SGM strains were isolated from sputum samples of suspected tuberculosis (TB) patients. SGM species were identified by standard phenotypic tests and were assigned to species level by amplification and sequencing of the dnaK gene. The minimum inhibitory concentration (MIC) of eight antibiotics was determined using broth microdilution method. The mutations in rrl, rpoB, gyrA, and gyrB genes were investigated in clarithromycin, rifampin, and moxifloxacin resistant isolates using sequencing method. A total of 77 SGM isolates including 46 (59.7%) Mycobacterium kansasii, 21 (27.3%) Mycbacterium simiae, and 10 (13%) Mycobacterium avium complex (MAC) were detected. The amikacin and linezolid with the susceptibility rates of 97.4% and 1.3% were the most and the least effective antibiotics, respectively. All MAC and M. simiae isolates, and 32 (69.6%) M. kansasii strains had multiple-drug resistance (MDR) profiles. The rrl, rpoB, gyrA, and gyrB genes showed various mutations in resistant isolates. Although the current study showed an association among resistance to the clarithromycin, rifampin, and moxifloxacin with mutations in the relevant genes, further research using the whole-genome sequencing is needed to provide a clearer insight into the molecular origins of drug resistance in SGM isolates.

Cytokine storm in tuberculosis and IL-6 involvement

Tuberculosis is probably the most seasoned illness of the humanity. Intricacies or subsequent death emerging from these infections are frequently connected with cytokine storm. Interleukin-6 (IL-6) plays a crucial role in the immune response to tuberculosis. Therefore, there is a need to research some new therapeutic approaches to block IL-6 signaling that are right now being applied to the M. tuberculosis. In this review, we investigate the implication of IL-6 in the context of tuberculosis research.

Occurrence and risk factors of nontuberculous mycobacteria in tuberculosis-suspected patients in the north of Iran

Background and Objectives:

Some Nontuberculous Mycobacteria (NTM) can occasionally infect the human population and cause infections having symptoms similar to tuberculosis (TB). This study tried to provide updated data about the frequency and diversity of NTM species.

Materials and Methods:

Suspicious samples of Mycobacterium tuberculosis (MTB) with both positive results in Ziehl-Neelsen (ZN) staining and Löwenstein-Jensen medium culturing were evaluated during January 2016 and December 2018 in Gorgan, Iran. After determination of MTB isolates by the growth rate, pigmentation status, the niacin test, and the insertion sequence 6110 (IS6110) PCR assay, other unknown isolates (presumably NTM) were detected by the 16S rDNA sequencing method and drawing the phylogenetic tree. Based on the patients’ demographic information, their risk factors were also assessed.

Results:

Among 226 culture-positive samples, obtained from 2994 individuals with suspected symptoms of TB, the analyses found 12 (5.3%) NTM and three Mycobacterium caprae isolates. Mycobacterium simiae (6/12) was the most prevalent NTM species. The average nucleotide similarity value was 98.2% ± 3.7. In comparison to patients with MTB (211 confirmed cases), other mycobacterium infections were more common in patients over 65 years old (Odd ratio (95% convenience interval): 2.96 (0.69 – 12.59), P = 0.14).

Conclusion:

Although the NTM species has a small portion in TB suspected patients, their prevalence has increased, mainly in elderly patients. Moreover, M. simiae was the most prevalent NTM species in our region. Therefore, identification of common species in each region is recommended and clinicians should pay more attention to them in each region.

Mycobacterium Tuberculosis and Nontuberculous Mycobacteria Isolates from Presumptive Pulmonary Tuberculosis Patients Attending A Tertiary Hospital in Addis Ababa, Ethiopia

Background

Mycobacterial infections are known to cause a public health problem globally. The burden of pulmonary disease from nontuberculous mycobacteria is reportedly on the rise in different parts of the world despite the fact that there is limited data about the disease in sub-Saharan Africa including Ethiopia. Hence, we aimed to assess the magnitude of M. tuberculosis and nontuberculous mycobacteria (NTM) among presumptive pulmonary tuberculosis patients attending St. Paul's hospital Medical College, Addis Ababa, Ethiopia.

Methods

A cross-sectional study was conducted from June to September 20/2016. Morning sputum specimens were collected, processed and cultured in Lowenstein Jensen medium and BACTEC MGIT 960 media. The nontuberculous mycobacteria were further confirmed and characterized by Genotype CM/AS assays. The socio-demographic, clinical and chest x-ray data were collected using a structured questionnaire. The data was analyzed using SPSS version 20.

Results

Out of 275 presumptive tuberculosis patients enrolled in the study, 29(10.5%) were culture positive for Mycobacteria. Of these, 3(10.3%) were found to be NTM and 26(89.6%) were Mycobacterium tuberculosis complex. Of the NTM, two were unidentified and one typed as M.peregrinum. There was no co-isolation of Mycobacterium tuberculosis complex and nontuberculous mycobacteria. Overall, 6(23.1%) Mycobacterium tuberculosis complex isolates were resistant to at least one anti-tuberculosis drug. Of these, two were multidrug resistant tuberculosis cases (7.7%) detected from previously treated patients.

Conclusion

Relatively low magnitude of Mycobacterium tuberculosis complex and nontuberculous mycobacteria isolates were seen in the study area. Therefore, further study using a large sample size is needed to be done to consider nontuberculous mycobacteria infection as a differential diagnosis in presumptive pulmonary tuberculosis patients.

Risk Factors for Complicated Lymphadenitis Caused by Nontuberculous Mycobacteria in Children

Nontuberculous mycobacteria (NTM) are an emerging cause of infections, including chronic lymphadenitis in children. To identify risk factors for NTM lymphadenitis, particularly complicated disease, we collected epidemiologic, clinical, and microbiological data on 138 cases of NTM lymphadenitis in children across 13 centers in Germany and Austria. We assessed lifestyle factors but did not identify specific risk behaviors. We noted that more cases of NTM lymphadenitis occurred during cold months than during warm months. Moreover, we noted female sex and age <5.5 years as potential risk factors. Complete extirpation of the affected lymph node appeared to be the best therapeutic measure. We integrated the study data to develop a simple risk score to predict unfavorable clinical outcomes for NTM lymphadenitis.

Incidence of nontuberculous mycobacterial disease and coinfection with tuberculosis in a tuberculosis-endemic region: A population-based retrospective cohort study

Nontuberculous mycobacteria (NTM) infection may interfere in the diagnosis and treatment of tuberculosis (TB) in TB-endemic regions. However, the population-based incidence of NTM disease and NTM-TB coinfection remains unclear.We used Taiwan's National Health Insurance Research Database to identify new diagnoses of NTM disease and TB from 2005 to 2013 and calculated the incidence rate and the proportion of NTM-TB coinfection. The patients with NTM disease or TB were determined by the use of disease codes from International Classification of Diseases, Ninth Revision, Clinical Modification, laboratory mycobacterium examination codes, and antimycobacterial therapy receipts.From 2005 to 2013, the age-adjusted incidence rate of NTM disease increased from 5.3 to 14.8 per 100,000 people per year and the age-adjusted incidence rate of NTM-TB coinfection was around 1.2 to 2.2 per 100,000 people per year. The proportion of NTM-TB coinfection among patients with confirmed TB was 2.8%. Male and older patients had a significantly higher incidence of NTM disease. The effects of urbanization and socioeconomic status (SES) on the incidences of TB and NTM disease were different. Rural living and lower SES were significantly associated with increasing the incidence of confirmed TB but not with that of NTM disease. For NTM disease, those living in the least urbanized area had significantly lower incidence rate ratio than in the highest urbanized area. The incidence of NTM-TB coinfection was higher in older patients and compared with patients aged < 45 years, the incidence rate ratio of the patients aged> 74 years was 12.5.In TB-endemic Taiwan, the incidence of NTM disease increased from 2005 to 2013. Male gender and old age were risk factors for high incidence of NTM disease. SES did not have a significant effect on the incidence of NTM disease, but rural living was associated with lower incidence of NTM disease. In TB-endemic areas, NTM-TB coinfection could disturb the diagnosis of TB and treatment, especially in elderly patients.

Trends in the Prevalence and Antibiotic Resistance of Non-tuberculous Mycobacteria in Mainland China, 2000-2019: Systematic Review and Meta-Analysis

Background: China is a high-burden country of tuberculosis. The proportion of diseases caused by non-tuberculous mycobacteria (NTM) has increased, seriously affecting the prevention, control, and management of tuberculosis (TB) and posing a significant threat to human health. However, there is a lack of an organized monitoring system for NTM such as that used for tuberculosis. Comprehensive data on patient susceptibility, dominant species, and drug resistance profiles are needed to improve the treatment protocols and the management of NTM. Methods: Primary research reports of NTM clinical specimens from mainland China published between January 1, 2000 and May 31, 2019 were retrieved from four online resources (BIOSIS, Embase, PubMed, and Web of Science) and three Chinese medical literature databases (CNKI, Wanfang, and Vip) as the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Results: In total, 339 publications were included in the systematic review, 129 were used in the drug susceptibility analysis, and 95 were used in the meta-analysis. Traditional culture using Lowenstein-Jensen slants combined with P-nitrobenzene acid and thiophene-2-carboxylic acid hydrazine differential medium and proportional method was most commonly used for the isolation, identification, and drug susceptibility testing of NTM in China. The crude isolation rate for NTM among TB suspected cases was 4.66-5.78%, while the proportion of NTM among Mycobacterium isolates was 11.57%. Mycobacterium abscessus and Mycobacterium avium complex were the most common clinical NTM species. NTM only showed general sensitivity to ethambutol, linezolid, clofazimine, amikacin, tobramycin, and clarithromycin. Conclusions: The prevalence of NTM in China has shown a decreasing trend. M. abscessus was replaced as the dominant species by Mycobacterium intracellulare over the course of the study. The geographic diversity of different species showed the effects of environmental and economic factors on the distribution of NTM and indicated that there were important factors still not identified. While there were only a limited number of antibiotics to which NTM showed any sensitivity, the drug resistance profiles of the isolates were highly variable and thus more caution should be taken when empirically treating NTM infection.

Drug susceptibility testing of Mycobacterium simiae: An emerging pathogen in Iran

INTRODUCTION

Mycobacterium simiaeis an emerging pathogen in Iran and little is known about drug susceptibility patterns of this pathogen.

MATERIALS AND METHODS

Twenty-five clinical isolates of M. simiaefrom 80 patients with confirmed NTM pulmonary disease were included in this study. For drug susceptibility testing (DST), proportional and broth microdilution methods were used according to the clinical and laboratory standards institute (CLSI) guideline.

RESULTS

All clinical isolates of M. simiaewere resistant to isoniazid, rifampicin, ethambutol, streptomycin, amikacin, kanamycin, ciprofloxacin, and clarithromycin. They also were highly resistant to ofloxacin (80%). Susceptibility to ofloxacin was only noted in the 5 isolates.

CONCLUSIONS

Clinical isolates of M. simiae were multidrug-resistant, and had different drug susceptibility patterns than previously published studies. DST results can assist in selecting more appropriate treatment regimens. Newer drugs with proven clinical efficacy correlating with in vitrosusceptibility should be substituted with first-and second-line anti-TB drug testing.

Molecular Identification, and Characterization of Mycobacterium kansasii Strains Isolated from Four Tuberculosis Regional Reference Laboratories in Iran During 2016-2018

Background

Non-tuberculous mycobacterial (NTM) infections are growing concern in many countries around the globe including Iran. Among them, Mycobacterium kansasii (M. kansasii) causes both pulmonary and extra-pulmonary infections. Despite the high prevalence of M. kansasii isolates in Iran, unfortunately little is known about the epidemiological aspects of M. kansasii infection. Hence, the aim of the present study was to investigate the molecular identification, determination of subtypes variation and geographic distribution of clinical isolates of M. kansasii isolates.

Methods

In the present study, 108 clinical pulmonary isolates suspected to NTM were collected from four Tuberculosis Regional Reference Laboratories in Iran during 2016–2018. The isolates were confirmed as NTM using conventional and molecular methods. Among them, M. kansasii isolates were subjected to rpoB gene sequencing. For determination of subtyping of M. kansasii isolates, polymerase chain reaction-restriction enzyme analysis (PCR-REA) based on the hsp65 gene was performed.

Results

Based on the rpoB gene sequence analysis, 33 (30.5%) isolates were identified as M. kansasii species, compared to 31 (28.7%) isolates using phenotypic methods. The subtype I was the most frequent subtype (n=24; 72.7%), followed by subtype II (n=8; 24.2%).

Conclusion

We indicated that the rate of M. kansasii isolation with clinical significance appears to be increasing in Iran, especially in highly industrialized cities. The high rate of M. kansasii subtype I may suggest that this genotype has a particular potency for colonization, and a higher epidemiological potential for causing infection in humans. More studies are needed to provide a better understanding of the biology and pathogenicity of M. kansasii subtype I.

Nontuberculous mycobacteria in patients with suspected tuberculosis and the genetic diversity of Mycobacterium avium in the extreme south of Brazil

Objective:

Nontuberculous mycobacteria (NTM) are a heterogeneous group of bacteria that are widely distributed in nature and associated with opportunistic infections in humans. The aims of this study were to identify NTM in patients with suspected tuberculosis who presented positive cultures and to evaluate the genetic diversity of strains identified as Mycobacterium avium.

Methods:

We studied pulmonary and extrapulmonary samples obtained from 1,248 patients. The samples that tested positive on culture and negative for the M. tuberculosis complex by molecular identification techniques were evaluated by detection of the hsp65 and rpoB genes and sequencing of conserved fragments of these genes. All strains identified as M. avium were genotyped using the eight-locus mycobacterial interspersed repetitive unit-variable-number tandem-repeat method.

Results:

We found that NTM accounted for 25 (7.5%) of the 332 mycobacteria isolated. Of those 25, 18 (72%) were M. avium, 5 (20%) were M. abscessus, 1 (4%) was M. gastri, and 1 (4%) was M. kansasii. The 18 M. avium strains showed high diversity, only two strains being genetically related.

Conclusions:

These results highlight the need to consider the investigation of NTM in patients with suspected active tuberculosis who present with positive cultures, as well as to evaluate the genetic diversity of M. avium strains.

The case report of Mycobacterium arupense wound infection in diabetes mellitus patients; the first report and literature review

Mycobacterium arupense is among the opportunist pathogens of atypical mycobacteria emergence (atypical mycobacteria) that is one of the isolated and reported environmental and clinical specimens. Numerous cases of osteo-articular infections of this bacterium are reported nowadays, while the pulmonary infection is rare. We identified Mycobacterium arupense in non-healing wound infection of an elderly woman with history of diabetes mellitus. She has negative tests for HIV, HBV and HCV, but was positive for HTLV-1. The patient was referred according to mild-fever, non-healing, destructive, and swelled lesion on her left foot. The mycobacterial wounds infection was suspected due to her non-conclusive previous treatment. The pathology, acid-fast staining, conventional and 16S rRNA sequencing confirmed the micro-organism to be M. arupense . Finally, the patient recovered following two-week consumption of clarithromycin, ethambutol and rifabutin. The results of this study provide evidence on the potential pathogenicity, clinical outcomes and treatment of infections caused by this bacterium.

Species Diversity, Molecular Characterization, and Antimicrobial Susceptibility of Opportunistic Actinomycetes Isolated from Immunocompromised and Healthy Patients of Markazi Province of Iran

Background

Actinomycetes widely exist in nature and these species cause infections in immunocompromised and healthy patients, although they are frequently found as members of the normal microbiota of humans and animals. These subsequent infections are often misdiagnosed as malignancy and tuberculosis. Due to this issue, the present study aimed to determine the presence and diversity of actinomycetes species causing infections in Iranian patients.

Materials and Methods

A total of 79 clinical samples collected from five hospitals in Markazi province were analyzed for the existence of actinomycetes using standard protocols for isolation and characterization of the isolates. The conventional tests were used for preliminary identification, the PCR amplification of hsp65 gene, the specific region of the 16S rRNA, and sequence analyses of 16S rRNA were applied for the genus and species identification. MICs of the antimicrobial agent were determined by the broth microdilution method and interpreted according to the NCCLS guidelines.

Results

A total of 17 (21.51%) actinomycetes isolates were recovered from clinical samples. In other analyzed samples, eight (10.12%) gram-positive, 12 (15.18) gram-negative bacteria, and six (7.6) fungi isolates were recovered. The most prevalent actinomycetes species were M. fortuitum (17.64%), N. Mexicana and S. heliomycini (11.76% each), and 10 species, ie, N. farcinica, M. lehmannii, M. flavescens, Arthrobacter crystalopoetis, N. neocaledoniensis, M. phocaicum, M. abscessus, M. arupense, M. setense, and N. cyriacigeorgica made up the single isolates. Results of DST illustrated that all of the isolates were susceptible to Amikacin, Levofloxacin, Ofloxacin, and Ciprofloxacin, whereas all of them were resistant to Rifampicin and Doxycycline.

Conclusion

In conclusion, increasing isolation of actinomycetes found in various clinical cases merits special attention by health authorities in developing countries. In health centers, action should be taken to increase awareness of appropriate diagnostic criteria and management guidelines for actinomycetes diseases. Furthermore, an increase in the number as well as the quality of national and regional reference laboratories may facilitate more accurate diagnosis of actinomycetes diseases.

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.

Molecular characterization of nontuberculous mycobacteria in hospital waters: a two-year surveillance study in Tehran, Iran

Microbiological control of hospital waters as one of the main sources of nontuberculous mycobacteria (NTM) is important for the prevention of NTM-associated illness. This study aimed to investigate the prevalence of NTM in the hospital water systems of Tehran, Iran. A total of 218 samples from different hospital waters (i.e., tap water and medical devices such as humidifying cup of oxygen manometer, dialysis devices, nebulizers, and dental units) were included in this study. Phenotypic and molecular tests were used to identify the isolated organisms to species level. Of 218, 85 (39.0%) samples at 37 °C and 87 (40.0%) samples at 25 °C were identified as NTM. Using hsp65-sequencing method, Mycobacterium lentiflavum was the most frequently encountered, followed by M. gordonae and M. paragordonae. No significant difference was seen in frequency and species in mycobacteria isolated at 37 °C and 25 °C temperatures. Humidifying cup of oxygen manometer had the most contaminated water among the investigated water distribution systems in hospitals. Isolation of NTM from hospital water sources is a serious public health problem in Iran and merits further attention by health authorities. Establishment of microbiological monitoring systems for hospital waters and expanding the number of facilitated laboratories are strongly recommended.

Mycobacterium avium complex infection in patients with human immunodeficiency virus: A systematic review and meta-analysis

BACKGROUND

Mycobacterium avium-intracellulare complex (MAC) is one of the leading causes of death among people living with human immunodeficiency virus (HIV). The current study was aimed to determine the frequency of MAC infection in patients infected with HIV.

METHODS

Embase, PubMed, and Web of Science were searched for relevant studies. All statistical analyses were performed by STATA version 14.

RESULTS

From 6,627 retrieved articles, 23 were included in the final analysis. A total of 18,463 patients with HIV were included in the analysis. The frequency of MAC infection in patients with HIV was found to be 10.6% (95% confidence interval, 6.9-14.2).

CONCLUSION

The relatively large fractions of HIV-infected patients were coinfected with MAC, which may poses significant public health problems. Continued progress in the development of rapid diagnostic methods and preventive therapy for MAC should lead to further improvements in survival and quality of life in patients with HIV.

Mycobacterium simiae pulmonary disease in Iran: systematic review and meta-analysis

Mycobacterium simiae is one of the most common nontuberculous mycobacteria (NTM) microorganisms causing lung disease in many countries in the world. A reliable estimate of the extent of M. simiae pulmonary disease has not been well investigated in Iran. We systematically searched multiple databases to identify relative studies. Studies were excluded if they did not use the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) diagnostic criteria for NTM diseases. Data were extracted independently and in duplicate. We assessed pooled estimate by using a random model effect, and sources of heterogeneity were assessed by using Cochran's Q and the I 2 statistic. The potential for publication bias was explored by using Begg's and Egger's tests. All analyses were conducted with Stata 14.0 (StataCorp, College Station, TX, USA). Of 172 articles identified, seven met the inclusion criteria. Of 355 patients who were culture positive for NTM, 82 had M. simiae pulmonary disease according to the ATS/IDSA diagnostic criteria. The pooled frequency of M. simiae pulmonary disease among patients with NTM was 25.0% (95% confidence interval, 16.8-33.2). No evidence of publication bias was observed among the included studies (p >0.05 for Begg's and Egger's tests). Clinical isolates of M. simiae are increasingly being recognized as a cause of pulmonary disease in Iran and need further attention by health authorities.

Infections in Iran

Currently some parasitic and viral infections, tuberculosis, brucellosis and hospital-acquired infections are challenging issues in Iran. Despite decreasing the rate of some infectious diseases in Iran in recent years, improved sanitation, active surveillance, comprehensive infection control strategies and monitoring appropriate use of antibiotics are indispensable.

Nontuberculous Mycobacteria Infections at a Provincial Reference Hospital, Cambodia

Prevalence of nontuberculous mycobacteria (NTM) disease is poorly documented in countries with high prevalence of tuberculosis (TB). We describe prevalence, risk factors, and TB program implications for NTM isolates and disease in Cambodia. A prospective cohort of 1,183 patients with presumptive TB underwent epidemiologic, clinical, radiologic, and microbiologic evaluation, including >12-months of follow-up for patients with NTM isolates. Prevalence of NTM isolates was 10.8% and of disease was 0.9%; 217 (18.3%) patients had TB. Of 197 smear-positive patients, 171 (86.8%) had TB confirmed (167 by culture and 4 by Xpert MTB/RIF assay only) and 11 (5.6%) had NTM isolates. HIV infection and past TB were independently associated with having NTM isolates. Improved detection of NTM isolates in Cambodia might require more systematic use of mycobacterial culture and the use of Xpert MTB/RIF to confirm smear-positive TB cases, especially in patients with HIV infection or a history of TB.

High rates of nontuberculous mycobacteria isolation from patients with presumptive tuberculosis in Iran

Nontuberculous mycobacteria (NTM) can cause disease which can be indistinguishable from tuberculosis (TB), posing a diagnostic and therapeutic challenge, particularly in low- and middle-income settings. We aimed to investigate the mycobacterial agents associated with presumptive clinical pulmonary TB in Iran. A total of 410 mycobacterial isolates, obtained between March 2014 and January 2016, from 7600 clinical samples taken from consecutive cases of presumptive diagnosis of TB were identified. Phenotypic and molecular tests were used to identify the isolated organisms to the species level. Single-locus and multilocus sequence analysis based on 16S rRNA, rpoB, hsp65 and ITS locus were used to confirm the results. Of 410 consecutive strains isolated from suspected TB subjects, 62 isolates (15.1%) were identified as NTM. Patients with positive NTM cultures met American Thoracic Society diagnostic criteria for NTM disease. Mycobacterium simiae was the most frequently encountered (38.7%), followed by Mycobacterium fortuitum (19.3%), M. kansasii (17.7%) and M. avium complex (8.0%). Isolation of NTM, including M. simiae, from suspected TB cases is a serious public health problem and merits further attention by health authorities, physicians and microbiologists.

The reliability of rifampicin resistance as a proxy for multidrug-resistant tuberculosis: a systematic review of studies from Iran

In Iran, patients showing rifampicin (RIF) resistance detected by the Xpert® MTB/RIF assay are considered as candidates for multidrug-resistant tuberculosis (MDR-TB) treatment. Despite the fact that RIF resistance has been used as a proxy for MDR-TB, little is known about the proportion of isoniazid (INH) resistance patterns in RIF-resistant TB. We systematically searched MEDLINE, Embase, and other databases up to March 2017 for studies addressing the proportion of INH resistance patterns in RIF-resistant TB in Iran. The data were pooled using a random effects model. Heterogeneity was assessed using Cochran's Q and I² statistics. A total of 11 articles met the eligibility criteria. Data analysis demonstrated that 33.3% of RIF-resistant isolates from new TB cases and 14.8% of RIF-resistant isolates from previously treated cases did not display resistance to INH. The relatively high proportion of INH susceptibility among isolates with RIF resistance indicated that RIF resistance may no longer predict MDR-TB in Iran. Therefore, the detection of RIF resistance by the Xpert MTB/RIF assay will require complementary detection of INH resistance by other drug susceptibility testing (DST) methods in order to establish the diagnosis of MDR-TB.

New Insights in to the Intrinsic and Acquired Drug Resistance Mechanisms in Mycobacteria

Infectious diseases caused by clinically important Mycobacteria continue to be an important public health problem worldwide primarily due to emergence of drug resistance crisis. In recent years, the control of tuberculosis (TB), the disease caused by Mycobacterium tuberculosis (MTB), is hampered by the emergence of multidrug resistance (MDR), defined as resistance to at least isoniazid (INH) and rifampicin (RIF), two key drugs in the treatment of the disease. Despite the availability of curative anti-TB therapy, inappropriate and inadequate treatment has allowed MTB to acquire resistance to the most important anti-TB drugs. Likewise, for most mycobacteria other than MTB, the outcome of drug treatment is poor and is likely related to the high levels of antibiotic resistance. Thus, a better knowledge of the underlying mechanisms of drug resistance in mycobacteria could aid not only to select the best therapeutic options but also to develop novel drugs that can overwhelm the existing resistance mechanisms. In this article, we review the distinctive mechanisms of antibiotic resistance in mycobacteria.

The prevalence of non-tuberculous mycobacterial infections in mainland China: Systematic review and meta-analysis

Despite increasing attention towards the non-tuberculous mycobacterial (NTM) diseases, the overall epidemiological information remains unavailable for China. A systematic review and meta-analysis was conducted using data of 105 qualified publications from Chinese mainland. The assay demonstrated that the prevalence of NTM infections among tuberculosis suspects was 6.3% (5.4%-7.4%) in mainland, while the Southeastern region had the highest NTM prevalence at 8.6% (7.1%-10.5%). In Northern China, slow growing mycobacteria (SGM) consistituted 63.7% of all the NTM isolates, while this rate in Southern China was 53.0%. More rapid growing mycobacteria (RGM) were present in southern China than the northern (χ² = 57.996, P < 0.001). According to the coastal provinces' data (from north to south), the NTM prevalence rate and the number of isolated NTM species increased apparently in accordance with geographic latitude. The information obtained in this assay will facilitate the NTM disease diagnosis and screening policy making in China.

Prevalence of nontuberculous mycobacteria isolated from environmental samples in Iran: A meta-analysis

BACKGROUND

While the most nontuberculous mycobacteria (NTMs) species are considered as opportunistic pathogens, some of them are related to several human infections. It is believed that environment is the main source for these infections. Distribution and scattering pattern of NTMs has not been well studied in Iran and a few studies about this subject have been done, so the aim of this study was to determine prevalence of NTMs in environmental samples from Iran.

MATERIALS AND METHODS

Data about prevalence of NTMs in environmental samples from Iran were obtained by searching databases. The studies presenting cross-sectional or cohort and the papers with sample size ≥30 were included. Then, the meta-analysis was performed using Comprehensive Meta-Analysis software and Cochran's Q and I² tests. The strategy search was based PRISMA protocol is available online (PRISMA, http://www.prisma-statement.org).

RESULTS

The results of this meta-analysis showed that overall combined prevalence of NTMs in environmental samples from Iran was 38.3%. The frequency of NTM was higher in the north of Iran (73.2%). The most prevalent rapid-growing mycobacterium was Mycobacterium fortuitum (19.8%), and the most dominant slow-growing mycobacterium was Mycobacterium flavescens (16.8%).

CONCLUSION

In regard to increasing incidence of disease in immunocompromised patients and existence of different types of mycobacteria species in environmental samples, efforts should be focused on measures that will specifically remove NTMs from habitats where susceptible individuals are exposed.

Prevalence of Non-Tuberculous Mycobacteria in Hospital Waters of Major Cities of Khuzestan Province, Iran

Non-tuberculous mycobacteria (NTM) are among the emerging pathogens in immunocompromised individuals including hospitalized patients. So, it is important to consider hospitals water supplies as a source for infection. The aim of this study was to determine the prevalence of NTM in the hospital aquatic systems of Khuzestan, South west of Iran. In total, 258 hospital water samples were collected and examined. After initial sample processing, sediment of each sample were inoculated into two Lowenstein-Jensen medium. The positive cultures were studied with phenotypic tests including growth rate, colony morphology, and pigmentation, with subsequent PCR- restriction enzyme analysis (PRA) and rpoB gene sequence analysis. Mycobacterial strains were isolated from 77 samples (29.8%), comprising 52 (70.1%) rapid growing, and 25 (32.4%) slow growing mycobacteria. Based on the overall results, M. fortuitum (44.1%) was the most common mycobacterial species in hospital water samples, followed by M. gordonae (n = 13, 16.8%) and M. senegalense (n = 5, 7.7%). In conclusion, current study demonstrated the NTM strains as one of the major parts of hospital water supplies with probable potential source for nosocomial infections. This finding also help to shed light on to the dynamics of the distribution and diversity of NTM in the water system of hospitals in the region of study.

The Prevalence of Drug-Resistant Tuberculosis in Mainland China: An Updated Systematic Review and Meta-Analysis

Background

In recent years, drug resistant tuberculosis (DR-TB) particularly the emergence of multi-drug-resistant tuberculosis (MDR-TB) has become a major public health issue. The most recent study regarding the prevalence of drug-resistant tuberculosis in mainland China was a meta-analysis published in 2011, and the subjects from the included studies were mostly enrolled before 2008, thus making it now obsolete. Current data on the national prevalence of DR-TB is needed. This review aims to provide a comprehensive and up-to-date assessment of the status of DR-TB epidemic in mainland China.

Methods

A systematic review and meta-analysis of studies regarding the prevalence of drug-resistant tuberculosis in mainland China was performed. Pubmed/MEDLINE, EMBASE, the Cochrane central database, the Chinese Biomedical Literature Database and the China National Knowledge Infrastructure Database were searched for studies relevant to drug-resistant tuberculosis that were published between January 1, 2012 and May 18, 2015. Comprehensive Meta-Analysis (V2.2, Biostat) software was used to analyse the data.

Results

A total of fifty-nine articles, published from 2012 to 2015, were included in our review. The result of this meta-analysis demonstrated that among new cases, the rate of resistance to any drug was 20.1% (18.0%–22.3%; n/N = 7203/34314) and among retreatment cases, the rate was 49.8% (46.0%–53.6%; n/N = 4155/8291). Multi-drug resistance among new and retreatment cases was 4.8% (4.0%–5.7%; n/N = 2300/42946) and 26.3% (23.1%–29.7%; n/N = 3125/11589) respectively. The results were significantly heterogeneous (p<0.001, I² tests). Resistance to isoniazid was the most common resistance observed, and HRSE (H: isoniazid; R: rifampicin; S: streptomycin; E: ethambutol) was the most common form for MDR among both new and retreatment cases. Different drug resistance patterns were found by subgroup analysis according to geographic areas, subject enrolment time, and methods of drug susceptibility test (DST).

Conclusions

The prevalence of resistance to any drug evidently dropped for both new and retreatment cases, and multi-drug resistance declined among new cases but became more prevalent among retreatment cases compared to the data before 2008. Therefore, drug-resistant tuberculosis, particularly multi-drug-resistant tuberculosis among retreatment TB cases is a public health issue in China that requires a constant attention in order to prevent increase in MDR-TB cases.