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

Genomic diversity and clinical relevance of Mycobacterium simiae

Introduction

Mycobacterium simiae is a slow-growing non-tuberculous mycobacterium that can cause non-tuberculous mycobacterium (NTM) pulmonary disease and extrapulmonary infections. Until now, detailed genomic and clinical characteristics, as well as possible transmission routes of this rare pathogen remain largely unknown.

Methods

We conducted whole genome sequencing of available M. simiae isolates collected at a tertiary care centre in Central Germany from 2006 to 2020 and set them into context with publicly available M. simiae complex sequences through phylogenetic analysis. Resistance, virulence and stress genes, as well as known Mycobacteriaceae plasmid sequences were detected in whole genome raw reads. Clinical data and course were retrieved and correlated with genomic data.

Results

We included 33 M. simiae sensu stricto isolates from seven patients. M. simiae showed low clinical relevance with only two patients fulfilling American Thoracic Society (ATS) criteria in our cohort and three receiving NTM-effective therapy. The bacterial populations were highly stable over time periods of up to 14 years, and no instances of mixed or re-infections with other strains of M. simiae were observed. Clustering with <12 single nucleotide polymorphisms distance was evident among isolates from different patients; however, proof for human-to-human transmission could not be established from epidemiological data.

Conclusion

Overall, the available sequence data for M. simiae complex was significantly extended and new insights into its pathogenomic traits were obtained. We demonstrate high longitudinal genomic stability within single patients. Although we cannot exclude human-to-human transmission, we consider it unlikely in the light of available epidemiological data.

Treatment management of M. simiae infection complicated by severe immune reconstitution syndrome in two patients living with HIV

Nontuberculosis mycobacterium are increasingly being identified as sources of disseminated infections in immunocompromised patients. These infections can be challenging to identify and treat due complexities of diagnosis and inherent resistance to many medications. We present two cases of patients with human immunodeficiency virus who had Mycobacterium simiae infections, complicated by immune reconstruction inflammatory syndrome (IRIS). We also present a review of the English literature surrounding the disease, including reported resistance patterns to antimicrobial therapy, which can be highly variable.

A glimpse into the genotype and clinical importance of non tuberculous mycobacteria among pulmonary tuberculosis patients: The case of Ethiopia

Laboratory identification of nontuberculous mycobacteria (NTM) species is not regularly performed while, they have a public health importance with a prevalence of more than 5% among pulmonary tuberculosis (PTB) patients in Ethiopia. Hence, this study aimed to identify the NTM species and their clinical significance among PTB patients. A retrospective study was conducted at the Ethiopian Public Health Institution’s (EPHI’s) national TB referral laboratory. Stored NTM isolates were genotyped using GenoType Mycobacterium CM/AS kit (Hain Life science, Germany). Data pertinent to the study was extracted from the EPHI’s database and patients’ medical records. Between January 2 & December 28 of 2017, a total of 3,834 samples were processed from 698 TB patients of whom 50% were female. Among 3,317 samples with mycobacterial culture results 7.3% were NTM and majority of them were identified from smear negative TB patients. M. simiae was the /predominant NTM among the genotyped isolates. All the studied NTM species were not clinically important however, considering the similarity of clinical and radiologic findings between NTM and MTBC infected patients, integrating NTM species identification in the routine TB laboratory diagnosis may augment clinicians’ decision particularly in DR-TB patients. Additional similar prospective study with a larger sample size is recommended. Moreover, urgent improvements on patients’ record keeping practice are required in the studied hospitals.

Drug susceptibility profiling and genetic determinants of drug resistance in Mycobacterium simiae isolates obtained from regional tuberculosis reference laboratories of Iran

Background

Among Non-tuberculous mycobacteria (NTM) which generally cause opportunistic infections, especially in immunocompromised hosts, Mycobacterium simiae (M. simiae) is one of the most important NTM, associated with pulmonary disease. The main concern about M. simiae infections is the extreme resistance of this NTM to antibiotics. There are limited studies about drug susceptibility testing (DST) and the causes of drug resistance in M. simiae. Hence, the current study aimed to identify the M. simiae isolates and to assess the drug resistance of the isolates using phenotypic and molecular methods.

Materials and methods

In this study, 50 clinical pulmonary isolates suspected of NTM were collected from regional tuberculosis reference laboratories in Iran. The isolates were identified as M. simiae by using standard biochemical tests and molecular methods. DST was performed for identified M. simiae isolates and additional 35 M. simiae isolates from the department archive, against eight drugs. The mutations in gyrA, gyrB, and rrl genes in clarithromycin and moxifloxacin resistant isolates were investigated by polymerase chain reaction (PCR) followed by sequencing.

Results

Out of 50 suspected NTM isolates, 25 isolates were detected as M. simiae species based on the biochemical tests, and 18 isolates were verified based on the rpoB gene sequence analysis to achieve a total of 53 isolates when the archive isolates were included. DST results showed that all 53 isolates were resistant to isoniazid, rifampin, and clofazimine. The rate of resistance to ethambutol and linezolid were 34 (64%), and 40 (76%) respectively. The highest susceptibility rate was demonstrated for amikacin 53 (100%) and clarithromycin 45(85%), followed by moxifloxacin 35(66%). Sequence analysis showed mutations in positions 2058 and 2059 of the rrl gene, as well non-synonymous mutation at codons 389, 444, and 571 of the gyrB gene. Sequence analysis showed no mutation in the gyrA gene. drug-resistant isolates with mutations showed higher MICs compared to non-mutant resistant isolates.

Conclusions

This study revealed amikacin, clarithromycin, and moxifloxacin as the most effective antibiotics. However, since M. simiae exhibited a high level of antibiotic resistance in vitro, therefore, species identification and determining the antibiotic susceptibility pattern of the isolates are essential before treatment.

Challenges in the management of slowly growing non-tuberculous mycobacteria causing pulmonary disease: Perspectives from a high burden country

PURPOSE

There is a dearth of data on epidemiology, diagnosis and management of slow growing non tuberculous mycobacteria(NTM) in India, despite being a TB endemic country. This study aims to describe the geographic distribution, risk factors, and the challenges in management of slow growing NTM causing pulmonary infections.

METHODS

Over a period of 3 years, all slow growing NTM received from pulmonary specimens at a tertiary care centre were further studied from electronic hospital records to correlate non tuberculous mycobacteria species with demographics, geographic location, describe comorbidities including immunosuppression, radiologic findings and treatment regimes.

RESULTS

M.intracellullare was found in the majority of isolates with significant geographic variation and M.simiae the second commonest found exclusively in southern states. Common comorbidities included a previous history of treatment for tuberculosis, structural lung disease as well as systemic risk factors. Disseminated disease only occurred in immunocompromised hosts as was expected, but at a high rate of 44%. Treatment completion and outcomes were difficult to attain in our population.

CONCLUSION

The burden of NTM infection and its management in India remain a challenge. Ensuring it is made a notifiable disease may improve the current situation.

Reactivation of Mycobacterium simiae after the recovery of COVID-19 infection

There are limited studies on the coinfection of coronavirus disease 2019 (COVID-19) with nontuberculous mycobacteria. Here, we briefly describe the reactivation of Mycobacterium simiae infection in a patient who had recovered from COVID-19 in October 2020, Iran. During the pandemic of COVID-19, other infectious agents should not be ignored.

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.

Seroprevalence of Epstein-Barr virus among children and adults in Tehran, Iran

Epstein–Barr virus (EBV) as a herpes virus can be associated with numerous infections and cancers. The virus is known to cause infectious mononucleosis. There is no accurate estimation of the seroprevalence of EBV in Tehran, so this study aimed to estimate the seroprevalence of EBV among children and adults in Tehran, Iran. This descriptive–analytical study was conducted from 2015 to 2019 in Tehran province. In this study, 1220 people were selected by cross-sectional sampling, and blood samples and demographic data were collected by questionnaire. An anti-EBV-VCA ELISA kit was used to determine the seroprevalence of IgG against viral capsid antigen (VCA) among children and adults. In this study, most of the participants were in the age range of 20–29 years (349 individuals). The results of the ELISA test showed that the highest number of positive cases were in people over 40 years (94.8%), 30–39 years (92.5%) and 20–29 years were (92.1%), respectively. On the other hand, the seroprevalence of EBV infection in boys and girls up to 3 years was about 50%, and in adults, up to 40 years, it was about 95% (p < 0.001). The results of this study showed that in Tehran, the seroprevalence of VCA-IgG varied from 70% in primary school children to more than 90% in adults up to 40 years, indicating a broad spread of the virus. The results also indicate that the seroprevalence of EBV is high among men and women in Tehran.

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.