Nontuberculous mycobacteria in the environment

In vitro and ex vivo activity of the fluoroquinolone DC-159a against mycobacteria

Antimicrobial resistance is a global health problem. In 2021, it was estimated almost half a million of multidrug-resistant tuberculosis (MDR-TB) cases. Besides, non-tuberculous mycobacteria (NTM) are highly resistant to several drugs and the emergence of fluoroquinolone (FQ) resistant M. tuberculosis (Mtb) is also a global concern making treatments difficult and with variable outcome. The aim of this study was to evaluate the activity of the FQ, DC-159a, against Mtb and NTM and to explore the cross-resistance with the currently used FQs.A total of 12 pre-extensively drug-resistant (XDR) Mtb, 2 XDR, 36 fully drug susceptible strains and 41 NTM isolates were included to estimate the in vitro activity of DC-159a, moxifloxacin (MOX) and levofloxacin (LX), using minimal inhibitory and bactericidal concentration (MIC and MBC). The activity inside the human macrophages and pulmonary epithelial cells were also determined.DC-159a was active in vitro and ex vivo against mycobacteria. Besides, it was more active than MOX/LX. Moreover, no cross-resistance was evidenced between DC-159a and LX/MOX as DC-159a could inhibit Mtb and MAC strains that were already resistant to LX/MOX.DC-159a could be a possible candidate in new therapeutic regimens for MDR/ XDR-TB and mycobacterioses cases.

Identification and Antimicrobial Susceptibilities for Patients with Non-tuberculous Mycobacteria Infection in Jeju Island: Single-Center Retrospective Study

BACKGROUND

The distribution of species and characteristics of non-tuberculous mycobacteria (NTM) differ, and surveillance data for changes in antimicrobial susceptibilities of NTM is insufficient. This study analyzed the changes in antimicrobial susceptibility trends across NTM species and assessed the appropriateness of empirical antimicrobial drugs for NTM.

MATERIALS AND METHODS

We retrospectively analyzed the clinical characteristics, including demographics, distribution of NTM species, antimicrobial drug susceptibilities, and outcomes, at a teaching hospital in Jeju Island from 2009 - 2022.

RESULTS

Overall, 342 patients were included in the analysis; 93.0% were classified into the pulmonary group (PG) and 7.0% into the extrapulmonary group (EPG). The isolation rate of Mycobacterium avium was significantly higher in PG (36.8% vs. 0%, P = 0.001), while that of Mycobacterium fortuitum was significantly higher in EPG (4.5% vs. 31.3%, P = 0.001). The antimicrobial susceptibility rate is higher against clarithromycin (89.9%) and amikacin (83.3%) and lower against rifampin (54.7%) and ethambutol (28.1%). The susceptibility rate to clarithromycin was over 80%, but those to rifampin and ethambutol showed decreasing annual trends. Of the 162 patients who received empirical antimicrobial therapy, actual antimicrobial susceptibility rates were high (90.1%) using empirical macrolide, and relatively low using ethambutol and rifampin (28.0% and 58.8%, respectively).

CONCLUSION

This is the first study of analysis of the distribution, baseline characteristics, and antimicrobial susceptibility of isolated NTM species in pulmonary and extrapulmonary patients in Jeju Island over 10 years. Policies that continuously monitor changes in susceptibility rate are required to ensure effective treatment strategies.

Prevalence and Characteristics of Non-tuberculous Mycobacteria (NTM) Infection in Recipients of Allogeneic Hematopoietic Stem Cell Transplantation: a Systematic Review and Meta-analysis

PURPOSE

Non-tuberculous mycobacteria (NTM) infections in hematopoietic stem cell transplantation (HSCT) recipients represent a diagnostic and therapeutic challenge. Here, we aimed to review and analyze current literature on incidence, clinical presentation, and outcome of NTM infection after allogeneic HSCT.

METHODS

We performed a systematic review and meta-analysis of available literature regarding NTM infection in children and adults receiving allogeneic HSCT.

RESULTS

We identified 56 articles eligible for the analysis. Among 15 studies, describing 15,798 allogeneic HSCT, we estimated a prevalence of 1.26% (95% CI 0.72, 1.93) of NTM after transplant. Analysis of 175 patients with NTM infection showed a median time of diagnosis of 318 days after HSCT, an increased prevalence in adults (82.9%), and a most frequent pulmonary involvement (44%). Comparison between children and adults revealed an earlier post-transplant disease onset (median 130 days vs 287 days) and most frequent non-pulmonary presentation in children. A vast heterogeneity of therapeutic approach reflected the lack of universal recommendations regarding drug combination and duration of therapy. Overall, NTM-related mortality accounted for 33% in this systematic review.

CONCLUSION

Although rare, NTM infections can complicate post-transplant course with a high mortality rate in children and adults. The lack of prospective studies and guidelines prevents identification of risk factors and therapeutic recommendations.

Epidemiology of Nontuberculous Mycobacteria in Tuberculosis suspects, Southwest of China, 2017-2022

Objectives

This study summarizes the epidemiological characteristics, species distribution, and drug sensitivity of clinical nontuberculous mycobacteria (NTM) isolates at the Public Health Clinical Center of Chengdu, China, from January 2017 to December 2022.

Methods

We retrospectively analyzed data from patients with clinically isolated NTM strains. Chi-square analysis assessed the rate of Mycobacterium strain isolation over 6 years.

Results

The number of samples tested for Mycobacterium tuberculosis (MTB) and/or NTM increased each year, while MTB detection decreased and NTM detection rose significantly each year (P=0.03). The average age of NTM patients was 51 ± 17.53 years, with a 14.1% HIV infection rate. The predominant isolates were Mycobacterium avium-intracellulare (MAC) and M. chelonae/M. abscessus, with 96.4% of cases being of Han ethnicity. Amikacin, moxifloxacin, and clarithromycin were effective against M. avium and M. intracellulare; linezolid, amikacin, and cefoxitin were effective against M. chelonae/M. abscessus. Over 90% of NTM cases originated from the respiratory tract.

Conclusion

The NTM isolation rate in Southwest China has risen in recent years, primarily among elderly patients with a high HIV co-infection rate. The main NTM isolates were MAC and M. chelonae/M. abscessus. Amikacin, moxifloxacin, clarithromycin, and linezolid exhibited strong antibacterial activity against SGM, while amikacin and linezolid displayed relatively better antibacterial activity against RGM. The prevalence of NTM infection may be positively associated with regional economic development and health conditions.

A case report on Mycobacterium houstonense infection after total hip arthroplasty

BACKGROUND

Mycobacterium houstonense is a category of rapidly growing mycobacteria that is gram-positive, acid-fast, polycrystalline, and non-spore-forming. There have been few reports of human infection caused by Mycobacterium houstonense worldwide.

CASE PRESENTATION

We present a case of chronic periprosthetic joint infection caused by Mycobacterium houstonense in an elderly female patient. The patient developed signs of infection after undergoing total hip arthroplasty. Despite receiving antibiotic treatment and revision surgery, the signs of infection recurred repeatedly. Multiple bacterial cultures during the treatment period were negative. Later, we identified the pathogenic bacteria Mycobacterium houstonense through mNGS testing, isolated the bacteria from the ultrasonically centrifuged fluid of the prosthesis and obtained drug sensitivity results. Finally, we performed a revision surgery and treated the patient with moxifloxacin and clindamycin. After treatment, the patient did not show signs of infection recurrence during 24 months of follow-up.

CONCLUSION

Through a relevant literature search, we believe that Mycobacterium houstonense may show higher sensitivity to amikacin and quinolone antibiotics. Additionally, clarifying occult infection sources through methods such as gene testing will improve the diagnosis and treatment of periprosthetic joint infection.

Case report: Intraabdominal infection of Mycobacterium syngnathidarum in an immunocompetent patient confirmed by whole-genome sequencing

Background

The taxonomic group of non-tuberculous mycobacteria (NTM) encompasses more than 190 species and subspecies, some of which can cause pulmonary and extrapulmonary diseases across various age groups in humans. However, different subspecies exhibit differential drug sensitivities, and traditional detection techniques struggle to accurately classify NTM. Therefore, clinicians need more effective detection methods to identify NTM subtypes, thus providing personalized medication for patients.

Case presentation

We present the case of a 47-year-old female patient diagnosed with an intraabdominal infection caused by Mycobacterium syngnathidarum. Despite computed tomography of the chest suggesting potential tuberculosis, tuberculosis infection was ruled out due to negative TB-DNA results for ascites fluid and sputum and limited improvement of lung lesions after treatment. Additionally, acid-fast staining and Lowenstein-Jensen culture results revealed the presence of mycobacterium in ascites fluid. Subsequent whole-genome sequencing (WGS) confirmed the DNA sequences of Mycobacterium syngnathidarum in colonies isolated from the ascites fluid, which was further corroborated by polymerase chain reaction and Sanger sequencing. Ultimately, the patient achieved a complete recovery following the treatment regimen targeting Mycobacterium syngnathidarum, which involved clarithromycin, ethambutol hydrochloride, pyrazinamide, rifampicin, and isoniazid.

Conclusion

This is the first reported case of Mycobacterium syngnathidarum infection in humans. Mycobacterium syngnathidarum was detected by WGS in this case, suggesting that WGS may serve as a high-resolution assay for the diagnosis of different subtypes of mycobacterium infection.

Analysis of the bacterial communities associated with pupae and winged or wingless adults of Lipoptena fortisetosa collected from cervids in Italy

The hippoboscid Lipoptena fortisetosa Maa, 1965 is a hematophagous ectoparasite of cervids that can bite humans. This fly is expanding its geographical range and is of concern for animal and human health since it can potentially harbour harmful microorganisms. This study was aimed at characterizing the bacterial communities of L. fortisetosa in its different life-cycle stages. Pupae and wingless adults were collected from cervids hunted in Tuscan-Emilian Apennines (central Italy) and pooled into groups of 10 by life stage (30 individual pupae; 1420 individual wingless adults). Winged flies were caught by sweep netting and separated into five pools of 10 insects. After DNA extraction, the bacterial content of each pool was analysed using 16 S metabarcoding. Results revealed that the composition and relative abundance of different taxa greatly differed in the three analysed groups. Wingless adults showed a high abundance of Bartonella (33.07%), which is almost absent in winged flies and pupae. Among the detected pathogens, four genera of concern for human health were found: Bartonella, Moraxella, Mycobacterium and Rickettsia. Interestingly reads similar to Bartonella bovis, Moraxella osloensis and Arsenophonus lipopteni Operational Taxonomic Unit (OTUs) were detected. These findings suggest the possible role of L. fortisetosa as a reservoir of pathogenic microorganisms, confirming the need for further investigation to ascertain its vectorial capacity.

Genomic Analyses of Longitudinal Mycobacterium abscessus Isolates in a Multicenter Cohort Reveal Parallel Signatures of In-Host Adaptation

BACKGROUND

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and an increasingly frequent cause of opportunistic infections. Mycobacterium abscessus complex (MABC) is one of the major NTM lung pathogens that disproportionately colonize and infect the lungs of individuals with cystic fibrosis (CF). MABC infection can persist for years, and antimicrobial treatment is frequently ineffective.

METHODS

We sequenced the genomes of 175 isolates longitudinally collected from 30 patients with MABC lung infection. We contextualized our cohort amidst the broader MABC phylogeny and investigated genes undergoing parallel adaptation across patients. Finally, we tested the phenotypic consequences of parallel mutations by conducting antimicrobial resistance and mercury-resistance assays.

RESULTS

We identified highly related isolate pairs across hospital centers with low likelihood of transmission. We further annotated nonrandom parallel mutations in 22 genes and demonstrated altered macrolide susceptibility co-occurring with a nonsynonymous whiB1 mutation. Finally, we highlighted a 23-kb mercury-resistance plasmid whose loss during chronic infection conferred phenotypic susceptibility to organic and nonorganic mercury compounds.

CONCLUSIONS

We characterized parallel genomic processes through which MABC is adapting to promote survival within the host. The within-lineage polymorphisms we observed have phenotypic effects, potentially benefiting fitness in the host at the putative detriment of environmental survival.

Non-tuberculous Mycobacterium Rhinosinusitis in an Immunocompetent Patient

Non-tuberculous mycobacteria (NTM) are slow-growing opportunistic pathogens that cause a variety of cutaneous, soft tissue, and pulmonary infections. On rare occasions, NTM causes chronic rhinosinusitis, with the majority of cases presenting in immunocompromised individuals. Other potential risk factors include the presence of foreign bodies, previous sinus surgery or chemoradiation, and use of contaminated water in sinus rinses. We report here a rare case of NTM rhinosinusitis in an otherwise immunocompetent 66-year-old female. The patient underwent functional endoscopic sinus surgery where intraoperative acid-fast bacteria cultures grew Mycobacterium abscessus. She received five weeks of broad-spectrum IV antibiotic therapy followed by three months of oral azithromycin, tigecycline, and linezolid. A one-year post-operative visit showed appropriate healing without crusting or visible infection. This case contributes to the small handful of documented presentations of NTM rhinosinusitis in immunocompetent patients. NTM should be considered when patients present with refractory rhinosinusitis as they may require extended courses of antibiotic treatment. Familiarity with risk factors can further expedite making a diagnosis, ensuring prompt initiation of treatment and relief of symptoms for patients.

Clinical characteristics of patients with non-tuberculous mycobacterial pulmonary disease: a seven-year follow-up study conducted in a certain tertiary hospital in Beijing

Background

The incidence of non-tuberculous mycobacterial pulmonary disease (NTM-PD) has increased in recent years. However, the clinical and immunologic characteristics of NTM-PD patients have received little attention.

Methods

NTM strains, clinical symptoms, underlying diseases, lung CT findings, lymphocyte subsets, and drug susceptibility tests (DSTs) of NTM-PD patients were investigated. Then, the counts of immune cells of NTM-PD patients and their correlation were evaluated using principal component analysis (PCA) and correlation analysis.

Results

135 NTM-PD patients and 30 healthy controls (HCs) were enrolled from 2015 to 2021 in a certain tertiary hospital in Beijing. The number of NTM-PD patients increased every year, and Mycobacterium intracellulare (M. intracellulare), M. abscessus, M. avium, and M. kansasii were the major pathogens of NTM-PD. The main clinical symptoms of NTM-PD patients were cough and sputum production, and the primary lung CT findings were thin-walled cavity, bronchiectasis, and nodules. In addition, we identified 23 clinical isolates from 87 NTM-PD patients with strain records. The DST showed that almost all of M. abscessus and M. avium and more than half of the M. intracellulare and M. avium complex groups were resistant to anti-tuberculosis drugs tested in this study. M. xenopi was resistant to all aminoglycosides. M. kansasii was 100% resistant to kanamycin, capreomycin, amikacin, and para-aminosalicylic acid, and sensitive to streptomycin, ethambutol, levofloxacin, azithromycin, and rifamycin. Compared to other drugs, low resistance to rifabutin and azithromycin was observed among NTM-PD isolates. Furthermore, the absolute counts of innate and adaptive immune cells in NTM-PD patients were significantly lower than those in HCs. PCA and correlation analysis revealed that total T, CD4⁺, and CD8⁺ T lymphocytes played an essential role in the protective immunity of NTM-PD patients, and there was a robust positive correlation between them.

Conclusion

The incidence of NTM-PD increased annually in Beijing. Individuals with bronchiectasis and COPD have been shown to be highly susceptible to NTM-PD. NTM-PD patients is characterized by compromised immune function, non-specific clinical symptoms, high drug resistance, thin-walled cavity damage on imaging, as well as significantly reduced numbers of both innate and adaptive immune cells.

Nonbacterial Microflora in Wastewater Treatment Plants: an Underappreciated Potential Source of Pathogens

Wastewater treatment plants (WWTPs) receive and treat large volumes of domestic, industrial, and urban wastewater containing pathogenic and nonpathogenic microorganisms, chemical compounds, heavy metals, and other potentially hazardous substances. WWTPs play an essential role in preserving human, animal, and environmental health by removing many of these toxic and infectious agents, particularly biological hazards. Wastewater contains complex consortiums of bacterial, viral, archaeal, and eukaryotic species, and while bacteria in WWTP have been extensively studied, the temporal and spatial distribution of nonbacterial microflora (viruses, archaea, and eukaryotes) is less understood. In this study, we analyzed the viral, archaeal, and eukaryotic microflora in wastewater throughout a treatment plant (raw influent, effluent, oxidation pond water, and oxidation pond sediment) in Aotearoa (New Zealand) using Illumina shotgun metagenomic sequencing. Our results suggest a similar trend across many taxa, with an increase in relative abundance in oxidation pond samples compared to influent and effluent samples, except for archaea, which had the opposite trend. Additionally, some microbial families, such as Podoviridae bacteriophages and Apicomplexa alveolates, appeared largely unaffected by the treatment process, with their relative abundance remaining stable throughout. Several groups encompassing pathogenic species, such as Leishmania, Plasmodium, Toxoplasma, Apicomplexa, Cryptococcus, Botrytis, and Ustilago, were identified. If present, these potentially pathogenic species could be a threat to human and animal health and agricultural productivity; therefore, further investigation is warranted. These nonbacterial pathogens should be considered when assessing the potential for vector transmission, distribution of biosolids to land, and discharge of treated wastewater to waterways or land. IMPORTANCE Nonbacterial microflora in wastewater remain understudied compared to their bacterial counterparts despite their importance in the wastewater treatment process. In this study, we report the temporal and spatial distributions of DNA viruses, archaea, protozoa, and fungi in raw wastewater influent, effluent, oxidation pond water, and oxidation pond sediments by using shotgun metagenomic sequencing. Our study indicated the presence of groups of nonbacterial taxa which encompass pathogenic species that may have potential to cause disease in humans, animals, and agricultural crops. We also observed higher alpha diversity in viruses, archaea, and fungi in effluent samples than in influent samples. This suggests that the resident microflora in the wastewater treatment plant may be making a greater contribution to the diversity of taxa observed in wastewater effluent than previously thought. This study provides important insights to better understand the potential human, animal, and environmental health impacts of discharged treated wastewater.

Nontuberculous Mycobacterial Tenosynovitis of the Hand: A 10-Year Experience at Two Centers in South Korea

Background

The aim of this study was to investigate the clinical characteristics of nontuberculous mycobacterial tenosynovitis and to report the process of diagnosis and the outcomes of surgical debridement and drug administration in South Korea.

Methods

Between 2010 and 2019, 23 patients (10 men and 13 women) with nontuberculous tenosynovitis of the hand were treated at two centers. Their average age was 64 years, and the average duration of symptoms was 8 months (range, 1-36 months). Eight patients had a history of trauma or surgery. The average number of corticosteroid injections before diagnosis was 2.6 for 7 patients. All 23 patients were treated with a combination of extensive tenosynovectomy and antibiotics.

Results

Of the 23 patients, 20 were available for the final follow-up (1, lost to follow-up; 1, transferred to another hospital; and 1, died from a comorbidity). The most common species was Mycobacterium intracellulare (70%), followed by Mycobacterium abscessus (10%). The frequency of involvement of the extensor/flexor tendon was similar to that of the wrist/finger. The mean number of surgical debridement operations was 2.2. The average duration of antibiotic administration was 9.8 months. At the last follow-up, 3 patients were symptom-free with full range of motion at the involved site, 1 patient complained of localized swelling or pain with full range of motion, 1 patient was found to have a recurrence of infection in a finger, and 15 complained of restricted joint motion.

Conclusions

The most common species noted in patients with nontuberculous mycobacterial tenosynovitis was M. intracellulare. Patients with only 1 finger involved showed good range of motion at the final follow-up. Most patients experienced delayed wound healing and adverse effects from drug therapy during treatment and limited joint motion at the final follow-up.

M ycobacterium avium complex genomics and transmission in a London hospital

BACKGROUND

Non-tuberculous mycobacteria (NTM) are environmental microorganisms and opportunistic pathogens in individuals with pre-existing lung conditions such as cystic fibrosis (CF) and non-CF bronchiectasis. While recent studies of Mycobacterium abscessus have identified transmission within single CF centres as well as nationally and globally, transmission of other NTM species is less well studied.

METHODS

To investigate the potential for transmission of the Mycobacterium avium complex (MAC) we sequenced 996 isolates from 354 CF and non-CF patients at the Royal Brompton Hospital (London, UK; collected 2013-2016) and analysed them in a global context. Epidemiological links were identified from patient records. Previously published genomes were used to characterise global population structures.

RESULTS

We identified putative transmission clusters in three MAC species, although few epidemiological links could be identified. For M. avium, lineages were largely limited to single countries, while for Mycobacterium chimaera, global transmission clusters previously associated with heater-cooler units (HCUs) were found. However, the immediate ancestor of the lineage causing the major HCU-associated outbreak was a lineage already circulating in patients.

CONCLUSIONS

CF and non-CF patients shared transmission chains, although the lack of epidemiological links suggested that most transmission is indirect and may involve environmental intermediates or asymptomatic carriage in the wider population.

A Rapid Screening Assay for Clarithromycin-Resistant Mycobacterium avium Complex Using Melting Curve Analysis with Nonfluorescent Labeled Probes

Mycobacterium avium complex (MAC) thrives in various environments and mainly causes lung disease in humans. Because macrolide antibiotics such as clarithromycin or azithromycin are key drugs for MAC lung disease, the emergence of macrolide-resistant strains prevents the treatment of MAC. More than 95% of macrolide-resistant MAC strains are reported to have a point mutation in 23S rRNA domain V. This study successfully developed a melting curve assay using nonfluorescent labeled probes to detect the MAC mutation at positions 2058 to 2059 of the 23S rRNA gene (AA genotype, clarithromycin susceptible; TA, GA, AG, CA, AC, and AT genotypes, clarithromycin resistant). In the AA-specific probe assay, the melting peak of the DNA fragment of the AA genotype was higher than that of DNA fragments of other genotypes. Melting temperature (Tm) values of the AA genotype and the other genotypes were about 80°C and 77°C, respectively. DNA fragments of each genotype were identified correctly in six other genotype-specific probes (TA, GA, AG, CA, AC, and AT) assays. Using genomic DNA from six genotype strains of M. avium and four genotype strains of M. intracellulare, we confirmed that all genomic DNAs could be correctly identified as individual genotypes according to the highest Tm values among the same probe assays. These results indicate that this melting curve-based assay is able to determine MAC genotypes at positions 2058 to 2059 of the 23S rRNA gene. This simple method could contribute to the rapid detection of clarithromycin-resistant MAC strains and help to provide accurate drug therapy for MAC lung disease. IMPORTANCE Since macrolide antibiotics such as clarithromycin or azithromycin are key drugs in multidrug therapy for Mycobacterium avium complex (MAC) lung diseases, the rapid detection of macrolide-resistant MAC strains has important implications for the treatment of MAC. Previous studies have reported a correlation between drug susceptibility testing and the mutation of macrolide resistance genes. In this study, we developed a novel melting curve-based assay using nonfluorescent labeled probes to identify both clarithromycin-resistant M. avium and M. intracellulare with mutations in the 23S rRNA gene, which is the clarithromycin or azithromycin resistance gene. This assay contributed to not only the detection of MAC mutations but also the determination of all genotypes at positions 2058 to 2059 of the 23S rRNA gene. Furthermore, because nonfluorescent labeled probes are used, this assay is more easily and more immediately available than other methods.

Scubcutaneous Mycobacterium marinum infection misdiagnosed as sporotrichosis: A case report

INTRODUCTION

Nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens.

PATIENT CONCERNS

In this report, we describe a case of scubcutaneous Mycobacterium marinum infection associated with home tropical ornamental fish aquaria. A 43-years-old man reported progressively increasing nodules over his left forearm and hand for more than 7 months.

DIAGNOSIS

Based on NTM culture, pathological examination, identification by gene sequencing and matrix assisted laser desorption ionization time of flight mass spectrometry, the diagnosis of scubcutaneous NTM infection was confirmed.

INTERVENTIONS

The patient was treated with itraconazole for suspected sporotrichosis over 1 month.

OUTCOMES

The patient was treated with oral doxycycline hydrochloride capsules (200 mg/day) for 5 months, the nodules had resolved.

CONCLUSION

Home aquarium environments may serve as a possible source of mycobacteria infection in urban family.

A Patient With Mycobacteremia Due to Two Different Nontuberculous Mycobacteria

Disseminated nontuberculous mycobacterial infections are most common in patients with severe immunosuppression, such as people with human immunodeficiency virus (HIV) and low CD4⁺ T-cell counts. In this report, we present a rare case of a person with HIV who was hospitalized for mycobacteremia due to 2 different nontuberculous mycobacteria. We also provide a comprehensive summary of published case reports describing nontuberculous mycobacterial coinfections.

Detection of non-tuberculosus mycobacteria (NTMs) in lung samples using 16S rRNA

BACKGROUND

Non-tuberculous mycobacteria (NTMs) cause diseases known as mycobacteriosis and are an important cause of morbidity and mortality. The diagnosis of pulmonary disease caused by NTM is hampered by its clinical similarity with tuberculosis (TB) and by the lack of an accurate and rapid laboratory diagnosis.

OBJECTIVES

Detect DNA from NTMs directly from lung samples using real-time polymerase chain reaction (qPCR) for amplification of 16S rRNA. Additionally, DNA sequencing (hsp65 and rpoB genes) was used to identify the species of MNTs.

METHODS

A total of 68 sputum samples (54 with suspected NTMs and 14 with TB) from patients treated at a referral hospital were used.

FINDINGS

Of these, 27/54 (50%) were qPCR positive for NTMs and 14/14 TB patients (controls) were qPCR negative with an almost perfect concordance (Kappa of 0.93) with the Mycobacterium spp. culture. Sequencing confirmed the presence of NTM in all positive samples. The most common species was Mycobacterium gordonae (33%), followed by Mycobacterium abscessus (26%), Mycobacterium fortuitum (22%), Mycobacterium avium (15%) and Mycobacterium peregrinum (4%).

MAIN CONCLUSIONS

The qPCR technique for detecting NTMs targeting 16S rRNA has the potential to detect NTMs and rapidly differentiate from Mycobacterium tuberculosis. However, it is necessary to identify the species to help in the differential diagnosis between disease and contamination, and to guide the choice of the therapeutic scheme.

Global prevalence of non-tuberculous mycobacteria in adults with non-cystic fibrosis bronchiectasis 2006-2021: a systematic review and meta-analysis

OBJECTIVE

To accurately estimate the global prevalence of non-tuberculous mycobacteria (NTM) in adults with non-cystic fibrosis (non-CF) bronchiectasis and to determine the proportion of NTM species and subspecies in clinical patients from 2006 to 2021.

DESIGN

Systematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

Medline, Embase, Cochrane Library and Web of Science were searched for articles published between 2006 and 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included all the prospective or retrospective studies without language restrictions and all patients were adults (≥18 years of age) with non-CF bronchiectasis. The studies estimated the effect size of the prevalence of NTM with a sample size ≥40, and patients were registered in and after 2006.

DATA EXTRACTION AND SYNTHESIS

Two reviewers screened the titles, abstracts and full texts independently. Relevant information was extracted and curated into tables. Risk of bias was evaluated following the Cochrane Collaboration's tool. Meta-analysis was performed with software R Statistics V.3.6.3 using random effect model with 95% CI. I² index and Q statistics were calculated to assess the heterogeneity, and mixed-effects meta-regression analyses were performed to identify the sources of heterogeneity. The proportions of NTM subspecies were examined using Shapiro-Wilk normality test in R.

RESULTS

Of all the 2014 studies yielded, 24 met the inclusion criteria. Of these, 14 were identified to be randomised controlled studies and included for an accurate estimation. The global prevalence of NTM in adults with non-CF bronchiectasis from 2006 to 2021 was estimated to be approximately 10%, with great variations primarily due to geographical location. Mycobacterium avium complex was the most common subspecies, followed by Mycobacterium simiae and Mycobacterium gordonae.

CONCLUSIONS

The prevalence of NTM in adults with non-CF bronchiectasis has been on the rise and the most common subspecies changed greatly in recent years. More cohort studies should be done in many countries and regions for future estimates.

PROSPERO REGISTRATION NUMBER

CRD42020168473.

[Patients with lung disease caused by non-tuberculous mycobacteria in Germany: a trans-sectoral patient-oriented care concept]

INTRODUCTION

Management of patients with lung disease caused by non-tuberculous mycobacteria (NTM-LD) in Germany is currently characterized by delayed diagnosis, frequently poor prognosis and high follow-up costs. Mainly due to an increased number of hospitalizations, the SHI-relevant direct costs (€ 9,093.20 patient/year) are higher compared to typical underlying diseases (e.g. asthma: € 706.00 patient/year). This less than optimal NTM care is mainly caused by lack of awareness of the disease at primary care and out-patient specialist care level, largely absent structured referral structures and limited communication between specialists out of hospital with specialized NTM clinics. Lack of incentives to support these communication pathways is part of the problem. Sufficient, appropriate and economically sustainable care is hampered by poor adherence to treatment recommendations.

METHODS

For the development of the NTM care concept, relevant professional societies and patient organizations were interviewed about the care situation. Thereafter, 20 NTM-LD patients, 5 residential pulmonologists and 8 experts were interviewed in an explorative qualitative interview to determine the current patient pathway. Based on the findings, the NTM care concept was developed in an advisory board by the authors.

RESULTS

Regional management centers should concentrate specific expertise and ensure quality of care through routine consultation and involvement in diagnosis, decision-making on treatment necessity, initiation of therapy, follow-up examinations, and determination of the therapy success, as well as adequate follow-up of patients. The referring pulmonologist should continue to provide case-specific therapy support close to the patient's home in preferred shared-care concept. The establishment of clear referral structures and case identification criteria will help residential physicians to include patients at risk in the NTM-care system early. Patients and pulmonologists without specific expertise need to be made aware of the care pathway and severity of NTM-LD.

CONCLUSION

The increased morbidity and mortality of NTM-LD patients must be addressed with patient-oriented, interdisciplinary and trans-sectoral care concept. An NTM care system with clear treatment procedures and referral structures is proposed for a nationwide pilot project.

Non-tuberculous mycobacteria pulmonary disease: A review of trends, risk factors, diagnosis and management

Non-tuberculous mycobacteria (NTM) reports have been on the rise globally, with increasing incidence and prevalence accompanied by poor outcomes. The rise has been attributed to an ageing population with increasing comorbid illnesses, and improved laboratory techniques in diagnosing the disease. However, despite the increase, some parts of the world still lack data, especially sub-Saharan African countries. The lack of data in our setting is difficult to explain, as we have a significant burden of NTM risk factors (i.e. HIV, tuberculosis and bronchiectasis). This review therefore serves as a reminder and a challenge to start searching, and reporting on our experiences. The review will highlight the rising incidence, important risk factors, diagnosis and management of NTM pulmonary disease.

Deep-Learning-Aided Detection of Mycobacteria in Pathology Specimens Increases the Sensitivity in Early Diagnosis of Pulmonary Tuberculosis Compared with Bacteriology Tests

The histopathological diagnosis of mycobacterial infection may be improved by a comprehensive analysis using artificial intelligence. Two autopsy cases of pulmonary tuberculosis, and forty biopsy cases of undetected acid-fast bacilli (AFB) were used to train AI (convolutional neural network), and construct an AI to support AFB detection. Forty-two patients underwent bronchoscopy, and were evaluated using AI-supported pathology to detect AFB. The AI-supported pathology diagnosis was compared with bacteriology diagnosis from bronchial lavage fluid and the final definitive diagnosis of mycobacteriosis. Among the 16 patients with mycobacteriosis, bacteriology was positive in 9 patients (56%). Two patients (13%) were positive for AFB without AI assistance, whereas AI-supported pathology identified eleven positive patients (69%). When limited to tuberculosis, AI-supported pathology had significantly higher sensitivity compared with bacteriology (86% vs. 29%, p = 0.046). Seven patients diagnosed with mycobacteriosis had no consolidation or cavitary shadows in computed tomography; the sensitivity of bacteriology and AI-supported pathology was 29% and 86%, respectively (p = 0.046). The specificity of AI-supported pathology was 100% in this study. AI-supported pathology may be more sensitive than bacteriological tests for detecting AFB in samples collected via bronchoscopy.

A case of a preschool child with a successful kidney transplant following the long-term administration of antibiotics to treat peritoneal dialysis-related ESI/peritonitis by Mycobacterium abscessus

A preschool child with refractory peritoneal dialysis-related exit-site infection (ESI)/peritonitis caused by Mycobacterium abscessus (M. abscessus) received multidrug antibacterial therapy for 6 months and then successfully underwent living-donor kidney transplantation. The patient was a 2.7-year-old boy and the primary disease was bilateral hypo/dysplastic kidneys. Peritoneal dialysis (PD) was initiated at the age of 4 months. Purulent drainage from the PD catheter exit site was observed, and pus and PD effluent cultures were negative. Since living kidney transplantation was scheduled for 2 months later, the PD catheter was replaced. Due to dialysate leakage from the exit site, the new PD catheter was removed and hemodialysis was initiated. M. abscessus subsequently grew from the PD effluent and abscesses that formed at the exit site continued to present bacteria even after catheter removal; therefore, additional debridement was performed. He received combination treatment with antibiotics, amikacin, clarithromycin, imipenem/cilastatin sodium, and tigecycline, for 6 months. After a 4-month observation period without antibiotics, the patient underwent living-donor kidney transplantation. The post-transplantation course was uneventful without the recurrence of infection for 2 years. Although PD-related ESI/peritonitis caused by M. abscessus was intractable, PD catheter removal, multiple debridement, and 6-month antibiotic combination therapy led to improvements. Follow-up observations for 4 months after the cessation of antibacterial treatment confirmed no recurrence of M. abscessus infection, which allowed kidney transplantation. The establishment of an appropriate treatment strategy and observation period for M. abscessus infection ahead of kidney transplantation requires further case accumulation.

Differentiating nontuberculous mycobacterium pulmonary disease from pulmonary tuberculosis through the analysis of the cavity features in CT images using radiomics

OBJECTIVE

To differentiate nontuberculous mycobacteria (NTM) pulmonary diseases from pulmonary tuberculosis (PTB) by analyzing the CT radiomics features of their cavity.

METHODS

73 patients of NTM pulmonary diseases and 69 patients of PTB with the cavity in Shandong Province Chest Hospital and Qilu Hospital of Shandong University were retrospectively analyzed. 20 patients of NTM pulmonary diseases and 20 patients of PTB with the cavity in Jinan Infectious Disease Hospitall were collected for external validation of the model. 379 cavities as the region of interesting (ROI) from chest CT images were performed by 2 experienced radiologists. 80% of cavities were allocated to the training set and 20% to the validation set using a random number generated by a computer. 1409 radiomics features extracted from the Huiying Radcloud platform were used to analyze the two kinds of diseases' CT cavity characteristics. Feature selection was performed using analysis of variance (ANOVA) and least absolute shrinkage and selection operator (LASSO) methods, and six supervised learning classifiers (KNN, SVM, XGBoost, RF, LR, and DT models) were used to analyze the features.

RESULTS

29 optimal features were selected by the variance threshold method, K best method, and Lasso algorithm.and the ROC curve values are obtained. In the training set, the AUC values of the six models were all greater than 0.97, 95% CI were 0.95-1.00, the sensitivity was greater than 0.92, and the specificity was greater than 0.92. In the validation set, the AUC values of the six models were all greater than 0.84, 95% CI were 0.76-1.00, the sensitivity was greater than 0.79, and the specificity was greater than 0.79. In the external validation set, The AUC values of the six models were all greater than 0.84, LR classifier has the highest precision, recall and F1-score, which were 0.92, 0.94, 0.93.

CONCLUSION

The radiomics features extracted from cavity on CT images can provide effective proof in distinguishing the NTM pulmonary disease from PTB, and the radiomics analysis shows a more accurate diagnosis than the radiologists. Among the six classifiers, LR classifier has the best performance in identifying two diseases.

Simultaneous Detection of Mycobacterium tuberculosis and Atypical Mycobacteria by DNA-Microarray in Egypt

BACKGROUND AND OBJECTIVES

Immunocompromised patients are a high-risk group for developing mycobacterial infections with either pulmonary and/or extrapulmonary diseases. Low-cost/density DNA-microarray is considered an easy and efficient method for the detection of typical and atypical mycobacterial species.

MATERIALS AND METHODS

Thirty immunocompromised patients were recruited to provide their clinical specimens (sputum, serum, urine, and lymph node aspirates). Real-time polymerase chain reaction (PCR) and DNA-microarray techniques were performed and compared to the conventional methods of Ziehl-Neelsen staining and Lowenstein Jensen culturing.

RESULTS

Mycobacterium tuberculosis complex was detected in all 30 clinical specimens (100% sensitivity) by real-time PCR and DNA-microarray. Additionally, coinfection with 4 atypical species belonging to nontuberculous mycobacteria was identified in 7 sputum specimens. These atypical mycobacterial species were identified as M. kansasii 10% (n = 3), M. avium complex 6.6% (n = 2), M. gordanae 3.3% (n = 1), and M. peregrinum 3.3% (n = 1).

CONCLUSION

This study documents the presence of certain species of atypical mycobacteria among immunocompromised patients in Egypt.

The frequency and related factors of non-tuberculosis mycobacteria infections among patients with cystic fibrosis

BACKGROUND

Non-tuberculous mycobacteria (NTM) can cause chronic lung infection particularly in patients who have structural lung disease such as cystic fibrosis (CF). We evaluated the incidence and management of NTM infections in patients with CF in our center.

METHODS

A retrospective cohort study was carried out on CF patients having at least one positive NTM isolate between 2012 and 2020.

RESULTS

Ten patients (2.1%) had at least one positive NTM culture from respiratory samples. All of them were vaccinated with Bacille Calmette-Guérin (BCG) vaccine, which is in the national vaccination program in our country. Eight patients had the Mycobacterium abscessus complex, one had Mycobacterium avium, and one had Mycobacterium szulgai growth in their respiratory samples. Three patients had transient NTM infection, two had persistent, and five had active NTM infection (NTM pulmonary disease). Patients with NTM pulmonary disease received antibiogram-directed antimycobacterial therapy. In patients with NTM pulmonary disease, the median ppFEV1 and BMI decreased by 17% and 1%, respectively, at the time of the first NTM isolation when compared with the values one year before the first NTM isolation. Culture conversion was not seen in any patient infected with Mycobacteriunm abscessus complex.

CONCLUSIONS

The NTM infection incidence is lower in our country than in those countries where the BCG vaccine is not routinely applied. The BCG vaccine may be a protective factor for NTM infection. Further studies are needed about the prevalence of NTM infections, facilitating and protective factors, and appropriate management of NTM infections in patients with CF.

A first case report of nasopharyngeal Mycobacterium abscessus subspecies massiliense infection

BACKGROUND

Mycobacterium abscessus subspecies massiliense is a non-tuberculous mycobacteriosis and was subdivided from Mycobacterium abscessus in 2006. This article is the first report on nasopharyngitis caused by Mycobacterium abscessus subspecies massiliense.

CASE PRESENTATION

A 45-year-old woman had an 18-month history of recurrent nasopharyngitis and presented with pain in the throat. Mycobacterial tissue culture and polymerase chain reaction testing revealed the presence of Mycobacterium abscessus subspecies massiliense in the nasopharyngeal tissue. This patient underwent surgery, followed by multiple rounds of chemotherapy with oral and intravenous antibiotic agents for 16 weeks. She has had no recurrence during the 56 weeks since treatment.

CONCLUSION

It is difficult to detect the presence of Mycobacterium abscessus subspecies massiliense in a culture from the swabbing sample. The tissue culture from a biopsy specimen is mandatory for the identification of the species. Currently, no definite treatment policy is available and only empirical treatment is applied. This case is an important for the diagnosis and treatment of this bacterial infection on nasopharynx.

Spontaneous resolution of Mycobacterium kansasii presenting as a spiculated lung mass

A 68-year old woman with a long smoking history underwent lung cancer screening by low-dose computed tomography. This detected a 3.0 cm spiculated mass in the left upper lobe. Transbronchial biopsy revealed necrotizing granulomatous inflammation and cultures grew Mycobacterium kansasii. Given lack of symptoms and concerns over drug toxicity, the patient declined antimicrobial therapy and she was monitored radiographically. Serial CT scans at six and twenty-two months showed progressive resolution of the mass. We present the first report of Mycobacterium kansasii presenting as a solitary lung nodule that spontaneously resolved without treatment.

Increasing Trend of Nontuberculous Mycobacteria Isolation in a Referral Clinical Laboratory in South Korea

Background and Objectives: Nontuberculous mycobacteria (NTM) infections are increasing worldwide. We evaluated the annual trends of NTM isolation on acid-fast bacillus (AFB) culture, compared to that of Mycobacterium tuberculosis, and the distribution of NTM species nationwide in South Korea. Materials and Methods: The study was conducted in a diagnostic center that is a major referral laboratory for the diagnosis of tuberculosis and NTM in South Korea. All laboratory results of AFB culture from January 2014 to December 2019 were collected. All NTM identified were definitively identified to the species level. Results: A total of 345,871 tests were performed for the diagnosis of mycobacteria. The isolation rate of NTM and M. tuberculosis was 3.7% (12,969 cases) and 4.4% (15,081 cases), respectively. The annual isolation rate of NTM increased gradually from 2.7% in 2014 to 4.8% in 2019, whereas that of M. tuberculosis decreased from 6.2% to 3.3%. There were 4988 cases of NTM identified to the species level. M. avium complex (MAC) was the most common species isolated from pulmonary sites (59.8%), followed by M. gordonae (9.2%), M. abscessus (7.0%), and M. fortuitum (5.5%). Extrapulmonary NTM were identified in 29 cases (0.6%). MAC was also the most common NTM species isolated from extrapulmonary sites (65.5%), followed by M. kansasii (10.3%), M. abscessus (6.9%), and M. fortuitum (6.9%). Conclusions: The annual isolation rate of NTM has increased gradually, whereas that of M. tuberculosis has decreased. Follow-up studies of the increases in NTM identification and NTM infections in South Korea are needed.

MYCOBACTERIA IN SKIN LESIONS AND THE HABITAT OF THE ENDANGERED HOUSTON TOAD (ANAXYRUS HOUSTONENSIS)

Head-starting of the federally endangered Houston toad (Anaxyrus houstonensis), that is, the release of egg strands, tadpoles, and metamorphic juveniles produced in captivity into the original breeding ponds, requires assessment of potential threats for the transmission of pathogens from captive to free-ranging toads. We used Illumina-based 16S rRNA V3 amplicon sequencing to investigate the community structure of bacteria from skin lesions of captive Houston toad and habitat (pond) samples. Proteobacteria, alone or together with Actinobacteria and, in some samples, Cyanobacteria represented virtually all reads in tissue lesion samples, whereas pond samples were much more diverse, with Acidobacteria, Actinobacteria, Bacteriodetes, Chloroflexi, Cyanobacteria, Firmicutes, Planctomycetes, Proteobacteria, and Verrucomicrobia present with little variation between samples. If present in lesions, Actinobacteria were largely represented by Mycobacteriaceae, and here mainly by one sequence identical to sequences of members of the Mycobacterium chelonae-abscessus complex. In pond samples, mycobacteria represented only a small portion of the actinobacteria, although at higher diversity with six distinct reads. Sequences for reads obtained from pond samples were identical to those representing the M. chelonae-abscessus complex, a group with Mycobacterium marinum, Mycobacterium kansasii, Mycobacterium avium, a group with Mycobacterium vaccae, Mycobacterium fortuitum, Mycobacterium poriferae, and a group with Mycobacterium elephantis and Mycobacterium celeriflavum, whereas sequences of high similarity were detected for reads related to those of Mycobacterium holsaticum, Mycobacterium pallens, and Mycobacterium obuense, and Mycobacterium goodii. Our results indicated that lesions observed on the Houston toad in captivity are not the result of mycobacteria in every case, and that the presence of mycobacteria in the captive colony does not represent a novel pathogen threat to the wild populations because such bacteria are also seen in the natural pond habitats for the Houston toad.

Extrapulmonary Nontuberculous Mycobacteria Infections in Hospitalized Patients, United States, 2009-2014

Nontuberculous mycobacteria (NTM) cause pulmonary and extrapulmonary infections in susceptible persons. To characterize the epidemiology of skin and soft tissue (SST) and disseminated extrapulmonary infections caused by NTM in the United States, we used a large electronic health record database to examine clinical, demographic, and laboratory data for hospitalized patients with NTM isolated from extrapulmonary sources during 2009–2014. Using all unique inpatients as the denominator, we estimated prevalence and summarized cases by key characteristics. Of 9,196,147 inpatients, 831 had confirmed extrapulmonary NTM. The 6-year prevalence was 11 cases/100,000 inpatients; source-specific prevalence was 4.4 SST infections/100,000 inpatients and 3.7 disseminated infections/100,000 inpatients. NTM species varied across geographic region; rapidly growing NTM were most prevalent in southern states. Infection with Mycobacterium avium complex was more common among patients with concurrent HIV and fungal infection, a relevant finding because treatment is more effective for M. avium complex than for other NTM infections.

A review of current and promising nontuberculous mycobacteria antibiotics

Nontuberculous mycobacteria infections are a growing concern, and their incidence has been increasing worldwide in recent years. Current treatments are not necessarily useful because many were initially designed to work against other bacteria, such as Mycobacterium tuberculosis. In addition, inadequate treatment means that resistant strains are increasingly appearing, particularly for Mycobacterium abscessus, one of the most virulent nontuberculous mycobacteria. There is an urgent need to develop new antibiotics specifically directed against these nontuberculous mycobacteria. To help in this fight against the emergence of these pathogens, this review describes the most promising heterocyclic antibiotics under development, with particular attention paid to their structure-activity relationships.

Phenotypic and genomic hallmarks of a novel, potentially pathogenic rapidly growing Mycobacterium species related to the Mycobacterium fortuitum complex

Previously, we have identified a putative novel rapidly growing Mycobacterium species, referred to as TNTM28, recovered from the sputum of an apparently immunocompetent young man with an underlying pulmonary disease. Here we provide a thorough characterization of TNTM28 genome sequence, which consists of one chromosome of 5,526,191 bp with a 67.3% G + C content, and a total of 5193 predicted coding sequences. Phylogenomic analyses revealed a deep-rooting relationship to the Mycobacterium fortuitum complex, thus suggesting a new taxonomic entity. TNTM28 was predicted to be a human pathogen with a probability of 0.804, reflecting the identification of several virulence factors, including export systems (Sec, Tat, and ESX), a nearly complete set of Mce proteins, toxin-antitoxins systems, and an extended range of other genes involved in intramacrophage replication and persistence (hspX, ahpC, sodA, sodC, katG, mgtC, ClpR, virS, etc.), some of which had likely been acquired through horizontal gene transfer. Such an arsenal of potential virulence factors, along with an almost intact ESX-1 locus, might have significantly contributed to TNTM28 pathogenicity, as witnessed by its ability to replicate efficiently in macrophages. Overall, the identification of this new species as a potential human pathogen will help to broaden our understanding of mycobacterial pathogenesis.

Atypical presentation of nontuberculous mycobacterial pulmonary infection in a patient with interstitial lung abnormality: A case report

Nontuberculous mycobacterial (NTM) infection is a common and important cause of chronic pulmonary disease, typically characterized by fibrocavitary and nodular-bronchiectatic forms on computed tomography (CT) of the chest. Structural lung disease and the host’s immune status can affect NTM pulmonary infections. Herein, we report a rare case of an NTM pulmonary infection with multiple nodules and masses (with internal cavitation) in an immunocompetent patient exhibiting interstitial lung abnormality on a chest CT.

Extracellular DNA of slow growers of mycobacteria and its contribution to biofilm formation and drug tolerance

DNA is basically an intracellular molecule that stores genetic information and carries instructions for growth and reproduction in all cellular organisms. However, in some bacteria, DNA has additional roles outside the cells as extracellular DNA (eDNA), which is an essential component of biofilm formation and hence antibiotic tolerance. Mycobacteria include life-threating human pathogens, most of which are slow growers. However, little is known about the nature of pathogenic mycobacteria’s eDNA. Here we found that eDNA is present in slow-growing mycobacterial pathogens, such as Mycobacterium tuberculosis, M. intracellulare, and M. avium at exponential growth phase. In contrast, eDNA is little in all tested rapid-growing mycobacteria. The physiological impact of disrupted eDNA on slow-growing mycobacteria include reduced pellicle formation, floating biofilm, and enhanced susceptibility to isoniazid and amikacin. Isolation and sequencing of eDNA revealed that it is identical to the genomic DNA in M. tuberculosis and M. intracellulare. In contrast, accumulation of phage DNA in eDNA of M. avium, suggests that the DNA released differs among mycobacterial species. Our data show important functions of eDNA necessary for biofilm formation and drug tolerance in slow-growing mycobacteria.

Combined administration of rifampicin, ethambutol, and clarithromycin for the treatment of tenosynovitis of the hand caused by Mycobacterium avium complex: Case series and literature review

ABSTRACT

We report the clinical results and problems of combined administration of rifampicin, ethambutol, and clarithromycin (REC) for the treatment of Mycobacterium avium complex (MAC) infection of the hand (hand MAC).Participants included 7 patients with hand MAC. After resection of the infected lesion, REC was prescribed for 12 months. For these patients, the site of infection, clinical course after initiation of REC, adverse drug effects (ADEs), and incidence of recurrence were evaluated.Sites of infection were the flexor tenosynovium in 5 patients, extensor tenosynovium in 1 patient, and both flexor and extensor tenosynovium in 1 patient. ADEs of REC occurred in 5 patients, and included visual disturbance caused by ethambutol in 2 patients, liver function abnormality caused by rifampicin in 2 patients, and fever with diarrhea caused by rifampicin in 1 patient. For 2 of these 5 patients, desensitization therapy was applied and REC was able to be reinstated. In the remaining 3 patients, the causative drugs were discontinued and levofloxacin, a new quinolone, was administered. Complete healing was achieved in 5 patients, and recurrence was observed in 2 patients. These 2 patients with recurrence included 1 patient in whom REC was completed and 1 patient in whom REC therapy was modified due to ADE.REC provided relatively good clinical results as a treatment for hand MAC. However, recurrences were observed even after the completion of REC and the use of an alternative drug. Optimal duration of REC and appropriate alternative drugs need to be identified in the future.

An update on prevalence of slow-growing mycobacteria and rapid-growing mycobacteria retrieved from hospital water sources in Iran - a systematic review

Introduction

This study aimed to assess the prevalence of slow growing mycobacteria (SGM) and rapid-growing mycobacteria (RGM) retrieved from hospital water sources in Iran from 2016 to 2020.

Methods

The review was conducted to get eligible published studies from 1^st January 2016 to 25^th March 2020 based on PRISMA protocol. A combination of related words from the Medical Subject Heading Terms (MeSH), with (AND, OR) were used to search for published studies reporting the prevalence of nontuberculous mycobacteria (NTM) in Scopus, MEDLINE, Web of Sciences, Google Scholar, and Iranian databases. Then data from the studies were extracted and reported.

Results

Our study showed that different water sources of hospitals were contaminated with NTMs. The prevalence of RGM isolates in hospital water samples varied between 42.2%-67.5%, and the prevalence of SGM varied between 32.5%-57.7%, respectively. M. lentiflavum (84.7%), M. avium complex(2.8%-56.4%)and M. gordonae (2.8%-56.2%) were the most prevalent NTM species amongst SGM, whereas M. fortuitum (2.9%-44.2%), M. chelonae (8%-36.8%), M. mucogenicum (8%-25.6%) were the most leading NTM isolates among RGM.

Conclusions

A high prevalence of NTM was reported from hospital environments particularly hospital water sources which can colonize medical devices, solutions, and water used for patients and cause nosocomial infection. Therefore, the hospitals should check the microbiological quality of the water used.

A Rare Case of Henoch-Schönlein Purpura and Mycobacterium xenopi Pulmonary Infection

Henoch-Schönlein purpura (HSP) is a small-vessel vasculitis with cutaneous, articular, gastrointestinal, and renal manifestations. Leukocytoclastic vasculitis and IgA deposits are classically found when involved skin and kidneys are biopsied. The disease's etiology remains unknown, although many bacterial and viral infections have been described as triggering factors.

A 53-year-old woman presented with fever, arthralgia, and non-thrombocytopenic purpura. She also had a segmental pulmonary collection with peripheral alveolar consolidation. Staphylococcus aureus and mycobacteria growth was found on sputum cultures. In addition to intravenous antibiotics and anti-mycotic drugs, high-dose corticosteroids were urgently administered due to the development of severe intestinal symptoms. A cutaneous biopsy later confirmed HSP. Microbial identification yielded Mycobacterium xenopi.

In the review of the literature, we only found 12 cases of Mycobacterium tuberculosis and one case of Mycobacterium avium-intracellulare complex that were associated with HSP. Nearly, half of the cases responded to anti-mycotic treatment alone. The rest required immunosuppressants. 

We report the first case of M. xenopi pulmonary infection in HSP. This disease process can have a severe course, which requires rapid recognition and treatment.

Performance of Interferon-Gamma Release Assays in the Diagnosis of Nontuberculous Mycobacterial Diseases-A Retrospective Survey From 2011 to 2019

There is an urgent need for precise diagnosis to distinguish nontuberculous mycobacterial (NTM) diseases from pulmonary tuberculosis (PTB) and other respiratory diseases. The aim of this study is to evaluate the diagnostic performance of Interferon-gamma (IFN-γ) release assays (IGRAs), including antigen-specific peripheral blood-based quantitative T cell assay (T-SPOT.TB) and QuantiFERON-TB-Gold-Test (QFT-G), in differentiating NTM infections (N = 1,407) from culture-confirmed PTB (N = 1,828) and other respiratory diseases (N = 2,652). At specie level, 2.56%, 10.73%, and 16.49% of NTM-infected patients were infected by Mycobacterium kansasii, M. abscessus, and with M. avmm-intracellulare complex (MAC), respectively. Valid analyses of T-SPOT.TB (ESAT-6, CFP-10) and QFT-G were available for 37.03% and 85.79% in NTM-infected patients, including zero and 100% (36/36) of M. kansasii infection, 21.85% (33/151) and 92.05% (139/151) of M. abscessus infection, and 17.67% (41/232) and 91.24% (211/232) of MAC infection. Based on means comparisons and further ROC analysis, T-SPOT.TB and QFT-G performed moderate accuracy when discriminating NTM from PTB at modified cut-off values (ESAT-6 < 4 SFCs, CFP-10 < 3 SFCs, and QFT-G < 0.667 IU/ml), with corresponding AUC values of 0.7560, 0.7699, and 0.856. At species level of NTM, QFT-G effectively distinguished between MAC (AUC=0.8778), M. kansasii (AUC=0.8834) or M. abscessus (AUC=0.8783) than T-SPOT.TB. No significant differences in discriminatory power of these three IGRA tools were observed when differentiating NTM and Controls. Our results demonstrated that T-SPOT.TB and QFT-G were both efficient methods for differentiating NTM disease from PTB, and QFT-G possessed sufficient discriminatory power to distinguish infections by different NTM species.

ATS Core Curriculum 2020. Adult Pulmonary Medicine

The American Thoracic Society Core Curriculum updates clinicians annually in adult and pediatric pulmonary disease, medical critical care, and sleep medicine in a 3- to 4-year recurring cycle of topics. The topics of the 2020 Pulmonary Core Curriculum include pulmonary vascular disease (submassive pulmonary embolism, chronic thromboembolic pulmonary hypertension, and pulmonary hypertension) and pulmonary infections (community-acquired pneumonia, pulmonary nontuberculous mycobacteria, opportunistic infections in immunocompromised hosts, and coronavirus disease [COVID-19]).

Non-tuberculous mycobacterial lung disease: a brief review focusing on radiological findings

The incidence and prevalence of lung disease caused by non-tuberculous mycobacteria (NTM-LD) has increased worldwide and its diagnosis represents a complex challenge. This article aims to review the tomographic findings of NTM-LD in order to facilitate their definitive diagnosis. The search for publications on the subject was performed in PMC and Scielo using the keywords 'non-tuberculous mycobacteria', 'lung disease and computed tomography (CT)' and 'radiological findings'. The radiological findings described by 18 articles on mycobacteriosis were reviewed. In addition, CT images of patients diagnosed with NTM-LD were considered to represent radiological findings. Eighteen publications were used whose main findings were pulmonary cavitation (88.9%), bronchiectasis (77.8%), and pulmonary nodules (55.6%). Despite the overlaps in imaging-related analysis of myocobacterioses with other pulmonary infections, such as tuberculosis, the predominant involvement of the middle lobe and lingula should raise suspicion for NTM-LD.

Mycobacterium marinum infection of the hand presenting as a nodular skin lesion

Nontuberculous mycobacteria have emerged as an important group of pathogens worldwide; however, infections of the hand are rare. Infections caused by nontuberculous mycobacteria are often opportunistic in humans, and notoriously difficult to treat due to intrinsic resistance to many antibiotics. Here we reported a case of Mycobacterium marinum infection of the hand in a patient who presented with a nodular skin lesion.

Flare or foe? - Mycobacterium marinum infection mimicking rheumatoid arthritis tenosynovitis: case report and literature review

Background

Rheumatoid arthritis is the most common type of inflammatory arthritis affecting about 1% of the population. With the advent of disease-modifying anti-rheumatic drugs the disease can be well controlled in many cases. Patients, however, are prone to developing infectious complications. In rare cases, these can mimic a flare of the underlying itself.

Case presentation

We report the case of a 45-year-old female patient with a history of seronegative rheumatoid arthritis (RA) who presented with swelling and tenderness of the third metacarpophalangeal joint of the right hand. A flare of her RA was suspected based on clinical and ultrasound findings which showed a tenosynovitis with intense power doppler activity. Her steroid dose was increased but the clinical response to glucocorticoid therapy was very limited. Subsequently, she developed skin manifestations of ‘swimmer’s granuloma’ over the next 2 weeks after first presentation. Finally, a diagnosis of a Mycobacterium marinum infection was established with the help of tissue biopsy and culture, and the patient received appropriate antibiotic treatment with the desired effect.

Conclusions

This case highlights the difficulty of distinction between infection and inflammation in patients with joint swelling and pain, especially in the age of disease-modifying drugs (DMARDs) and the concomitant risk of atypical infections. A review of the literature identified eight additional published cases, which suggests that Mycobacterium marinum infection is a rare but recognized complication of DMARD therapy. It can mimic a flare of the underlying arthritis potentially leading to diagnostic delays, and requires differential diagnostic methods to identify the pathogen and pave the way for appropriate treatment.

Clusters of nontuberculous mycobacteria linked to water sources at three Veterans Affairs medical centers

Objective:

To characterize nontuberculous mycobacteria (NTM) associated with case clusters at 3 medical facilities.

Design:

Retrospective cohort study using molecular typing of patient and water isolates.

Setting:

Veterans Affairs Medical Centers (VAMCs).

Methods:

Isolation and identification of NTM from clinical and water samples using culture, MALDI-TOF, and gene population sequencing to determine species and genetic relatedness. Clinical data were abstracted from electronic health records.

Results:

An identical strain of Mycobacterium conceptionense was isolated from 41 patients at VA Medical Centers (VAMCs A, B, and D), and from VAMC A’s ICU ice machine. Isolates were initially identified as other NTM species within the M. fortuitum clade. Sequencing analyses revealed that they were identical M. conceptionense strains. Overall, 7 patients (17%) met the criteria for pulmonary or nonpulmonary infection with NTM, and 13 of 41 (32%) were treated with effective antimicrobials regardless of infection or colonization status. Separately, a M. mucogenicum patient strain from VAMC A matched a strain isolated from a VAMC B ICU ice machine. VAMC C, in a different state, had a 4-patient cluster with Mycobacterium porcinum. Strains were identical to those isolated from sink-water samples at this facility.

Conclusion:

NTM from hospital water systems are found in hospitalized patients, often during workup for other infections, making attribution of NTM infection problematic. Variable NTM identification methods and changing taxonomy create challenges for epidemiologic investigation and linkage to environmental sources.

Infectious Lung Disease

Infectious diseases are one of the main causes of morbidity and mortality worldwide. With new pathogens continuously emerging, known infectious diseases reemerging, increasing microbial resistance to antimicrobial agents, global environmental change, ease of world travel, and an increasing immunosuppressed population, recognition of infectious diseases plays an ever-important role in surgical pathology. This becomes particularly significant in cases where infectious disease is not suspected clinically and the initial diagnostic workup fails to include samples for culture. As such, it is not uncommon that a lung biopsy becomes the only material available in the diagnostic process of an infectious disease. Once the infectious nature of the pathological process is established, careful search for the causative agent is advised. This can often be achieved by examination of the hematoxylin and eosin-stained sections alone as many organisms or their cytopathic effects are visible on routine staining. However, ancillary studies such as histochemical stains, immunohistochemistry, in situ hybridization, or molecular techniques may be needed to identify the organism in tissue sections or for further characterization, such as speciation.

Revisiting John Snow to Meet the Challenge of Nontuberculous Mycobacterial Lung Disease

Nontuberculous mycobacteria (NTM) are ubiquitous components of the soil and surface water microbiome. Disparities by sex, age, and geography demonstrate that both host and environmental factors are key determinants of NTM disease in populations, which predominates in the form of chronic pulmonary disease. As the incidence of NTM pulmonary disease rises across the United States, it becomes increasingly evident that addressing this emerging human health issue requires a bold, multi-disciplinary research framework that incorporates host risk factors for NTM pulmonary disease alongside the determinants of NTM residence in the environment. Such a framework should include the assessment of environmental characteristics promoting NTM growth in soil and surface water, detailed evaluations of water distribution systems, direct sampling of water sources for NTM contamination and species diversity, and studies of host and bacterial factors involved in NTM pathogenesis. This comprehensive approach can identify intervention points to interrupt the transmission of pathogenic NTM species from the environment to the susceptible host and to reduce NTM pulmonary disease incidence.