Mycobacterium kansasii

Detection of Mtb and NTM: preclinical validation of a new asymmetric PCR-binary deoxyribozyme sensor assay

Tuberculosis (TB) and infectious diseases caused by non-tuberculous mycobacteria (NTM) are global concerns. The development of a rapid and accurate diagnostic method, capable of detecting and identifying different mycobacteria species, is crucial. We propose a molecular approach, the BiDz-TB/NTM, based on the use of binary deoxyribozyme (BiDz) sensors for the detection of Mycobacterium tuberculosis (Mtb) and NTM of clinical interest. A panel of DNA samples was used to evaluate Mtb-BiDz, Mycobacterium abscessus/Mycobacterium chelonae-BiDz, Mycobacterium avium-BiDz, Mycobacterium intracellulare/Mycobacterium chimaera-BiDz, and Mycobacterium kansasii-BiDz sensors in terms of specificity, sensitivity, accuracy, and limit of detection. The BiDz sensors were designed to hybridize specifically with the genetic signatures of the target species. To obtain the BiDz sensor targets, amplification of a fragment containing the hypervariable region 2 of the 16S rRNA was performed, under asymmetric PCR conditions using the reverse primer designed based on linear-after-the-exponential principles. The BiDz-TB/NTM was able to correctly identify 99.6% of the samples, with 100% sensitivity and 0.99 accuracy. The individual values of specificity, sensitivity, and accuracy, obtained for each BiDz sensor, satisfied the recommendations for new diagnostic methods, with sensitivity of 100%, specificity and accuracy ranging from 98% to 100% and from 0.98 to 1.0, respectively. The limit of detection of BiDz sensors ranged from 12 genome copies (Mtb-BiDz) to 2,110 genome copies (Mkan-BiDz). The BiDz-TB/NTM platform would be able to generate results rapidly, allowing the implementation of the appropriate therapeutic regimen and, consequently, the reduction of morbidity and mortality of patients.IMPORTANCEThis article describes the development and evaluation of a new molecular platform for accurate, sensitive, and specific detection and identification of Mycobacterium tuberculosis and other mycobacteria of clinical importance. Based on BiDz sensor technology, this assay prototype is amenable to implementation at the point of care. Our data demonstrate the feasibility of combining the species specificity of BiDz sensors with the sensitivity afforded by asymmetric PCR amplification of target sequences. Preclinical validation of this assay on a large panel of clinical samples supports the further development of this diagnostic tool for the molecular detection of pathogenic mycobacteria.

Concomitantly Diagnosed Disseminated M kansasii Infection and Hairy Cell Leukemia With Review of Pathophysiology

The association between Hairy Cell Leukemia (HCL) and non-tuberculous mycobacterial infections (NTMs) is well described, most notably Mycobacterium kansasii. The exact pathophysiology is not known. We report a case of a 31-year-old male with concomitantly diagnosed HCL and disseminated M kansasii infection who presented with rash, pancytopenia, and bulky axillary lymphadenopathy. The M kansasii was initially diagnosed through use of cell-free DNA detection and confirmed by bone marrow and lymph node cultures. Hairy Cell Leukemia was diagnosed with peripheral flow cytometry and confirmed via the same bone marrow sample. His HCL was put into remission with a single course of cladribine and rituximab chemotherapy; however, his M kansasii infection persisted for 6 months despite aggressive antimicrobial and surgical therapy. It was finally controlled using high-dose rifampin in combination with azithromycin and ethambutol. This case highlights the known link between HCL and M kansasii. Furthermore, it hints at potential causes beyond chemotherapy-induced immunocompromise. Notable possibilities include HCL cells acting as sanctuary sites for M kansasii to evade the immune system, and subclinical M kansasii infections causing NLRP3 inflammasome overactivation to trigger the oncogenic transformation to HCL. More research into the pathophysiologic link between HCL and M kansasii infections would allow for more effective prevention, diagnosis, and treatment of these severe atypical infections which are the major cause of morbidity in the cladribine era of HCL treatment.

Treatment of the Less Common Nontuberculous Mycobacterial Pulmonary Disease

Nontuberculous mycobacterial pulmonary disease caused by the less common nontuberculous mycobacteria have distinct features depending on the species. Diagnostic evaluation follows the established criteria for all nontuberculous mycobacteria, but with certain qualifications given species-specific and regional differences in pathogenicity. Clinicians should first institute nonpharmacologic management and evaluate clinical, radiologic, and microbiologic factors in the decision regarding antimycobacterial therapy. Treatment is challenging, and evidence-based recommendations are limited for most species. Drug susceptibility testing is used to help with regimen selection; however, this approach is imperfect given the uncertain correlation between in vitro activity and clinical response for most drugs.

Dual M. kansasii infection in one household: a reconsideration of our understanding of transmission routes

Mycobacterium kansasii is one of the the most common non-tuberculous mycobacteria responsible for opportunistic human infection. Unlike M. tuberculosis, transmission remains poorly understood; spread is assumed to be from a shared geographical source, such as domestic plumbing, and human-to-human transmission is generally not considered by clinicians when evaluating patients and their environments. We describe M. kansasii infection in a husband and wife in the same household and in the same period, suggesting, in these cases, that transmission occurred directly from one patient to the other. This possibility of human-to-human transmission may inform a clinician's scrutiny of risks to household contacts in cases of M. kansasii infection.

Comprehensive essentiality analysis of the Mycobacterium kansasii genome by saturation transposon mutagenesis and deep sequencing

Mycobacterium kansasii (Mk) is an opportunistic pathogen that is frequently isolated from urban water systems, posing a health risk to susceptible individuals. Despite its ability to cause tuberculosis-like pulmonary disease, very few studies have probed the genetics of this opportunistic pathogen. Here, we report a comprehensive essentiality analysis of the Mk genome. Deep sequencing of a high-density library of Mk Himar1 transposon mutants revealed that 86.8% of the chromosomal thymine-adenine (TA) dinucleotide target sites were permissive to insertion, leaving 13.2% TA sites unoccupied. Our analysis identified 394 of the 5,350 annotated open reading frames (ORFs) as essential. The majority of these essential ORFs (84.8%) share essential mutual orthologs with Mycobacterium tuberculosis (Mtb). A comparative genomics analysis identified 139 Mk essential ORFs that share essential orthologs in four other species of mycobacteria. Thirteen Mk essential ORFs share orthologs in all four species that were identified as being not essential, while only two Mk essential ORFs are absent in all species compared. We used the essentiality data and a comparative genomics analysis reported here to highlight differences in essentiality between candidate Mtb drug targets and the corresponding Mk orthologs. Our findings suggest that the Mk genome encodes redundant or additional pathways that may confound validation of potential Mtb drugs and drug target candidates against the opportunistic pathogen. Additionally, we identified 57 intergenic regions containing four or more consecutive unoccupied TA sites. A disproportionally large number of these regions were located upstream of pe/ppe genes. Finally, we present an essentiality and orthology analysis of the Mk pRAW-like plasmid, pMK1248. IMPORTANCE Mk is one of the most common nontuberculous mycobacterial pathogens associated with tuberculosis-like pulmonary disease. Drug resistance emergence is a threat to the control of Mk infections, which already requires long-term, multidrug courses. A comprehensive understanding of Mk biology is critical to facilitate the development of new and more efficacious therapeutics against Mk. We combined transposon-based mutagenesis with analysis of insertion site identification data to uncover genes and other genomic regions required for Mk growth. We also compared the gene essentiality data set of Mk to those available for several other mycobacteria. This analysis highlighted key similarities and differences in the biology of Mk compared to these other species. Altogether, the genome-wide essentiality information generated and the results of the cross-species comparative genomics analysis represent valuable resources to assist the process of identifying and prioritizing potential Mk drug target candidates and to guide future studies on Mk biology.

Prevalence of systemic and local risk factors for pulmonary non-tuberculous mycobacterial disease in Japan: a single-institution study

Objective: To identify the prevalence of risk factors for pulmonary non-tuberculous mycobacterial (NTM) disease in a Japanese population. Patients and Methods: We reviewed 337 consecutive Japanese patients (210 women) with pulmonary NTM disease, including 225 patients with Mycobacterium avium complex (MAC) disease (95.8%) at our hospital during 2006-2017. We calculated the prevalence of risk factors reported in Western countries among mycobacterial species. Results: Pulmonary MAC disease cases comprised 78.2% of pulmonary NTM patients in their 40s, increasing to 100% at age ≥80 years. Body mass index (BMI) was <18.5 in approximately 40% of patients, which was significantly higher than the prevalence of underweight in the Japanese population. The percentage of male heavy smokers (Brinkman index ≥600) was 58.2% of pulmonary NTM disease and was high for all mycobacterial species. In pulmonary MAC disease, systemic factors were observed in the order of malignant tumors (other than lung cancer), diabetes, rheumatoid arthritis, and tuberculosis. Local factors were observed in the order of bronchiectasis, chronic obstructive pulmonary disease, lung cancer, and bronchial asthma. Conclusion: The risk factors reported in Western countries were relatively highly prevalent among Japanese pulmonary NTM disease patients. This observation may help elucidate disease onset mechanisms.

Spontaneous pneumothorax and COVID-19: Precipitants to a complex HIV-AIDS diagnosis

A 48-year-old male presented with spontaneous pneumothorax requiring chest tube placement in the setting of COVID-19 infection. CT chest revealed bilateral ground-glass opacities and multiple, large, gas-filled, cavitary lesions in the lungs bilaterally. These imaging findings led to an initial HIV diagnosis with the patient presenting at a CD4+ count of <32 cells/µL. He was found to additionally have infections with Mycobacterium kansasii, cytomegalovirus, Pneumocystis jirovecii, and Candida albicans. After developing worsening hypoxic respiratory failure, he developed additional pneumothoraces bilaterally, requiring repeated chest tube placement. He was treated with antimicrobial therapy for his underlying infections and subsequently started on combined antiretroviral therapy.

The Other Nontuberculous Mycobacteria: Clinical Aspects of Lung Disease Caused by Less Common Slowly Growing Nontuberculous Mycobacteria Species

Slowly growing nontuberculous mycobacteria (NTM) comprise a diverse group of environmental organisms, many of which are important human pathogens. The most common and well-known member of this group is Mycobacterium avium, the leading cause of nontuberculous mycobacterial pulmonary disease (NTM-PD) globally. This review focuses on the less common, but notable, species of slowly growing NTM with respect to lung disease. To prepare this article, literature searches were performed using each species name as the key word. Society guidelines were consulted, and relevant articles also were identified through the reference lists of key articles. The specific organisms highlighted include Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium malmoense, Mycobacterium simiae, and Mycobacterium szulgai. Although these organisms are closely related, they have distinct epidemiologic features and behavior as pathogens. Therefore, the diagnosis and management of NTM-PD require a nuanced approach that takes into consideration the unique characteristics of each species. There is limited evidence to inform the optimal treatment of NTM-PD. Antimicrobial therapy is often challenging because of the presence of drug resistance and few antibiotic options. Regimen selection should generally be guided by drug susceptibility testing, although the correlation between clinical outcomes and in vitro susceptibility thresholds has not been defined for most species.

Clinical Features of Nontuberculous Mycobacterial Pulmonary Disease in the Yangtze River Delta of China: A Single-Center, Retrospective, Observational Study

With increased focus on nontuberculous mycobacterial pulmonary disease (NTM-PD), and the improvement in detection methods, the global incidence continues to increase every year, but the diagnosis and treatment are difficult with a high misdiagnosis rate and poor curative effect. This study aimed to analyze the clinical indicators of different pathogenic NTM in the Yangtze River Delta. The study retrospectively analyzed the medical records of patients with NTM-PD, who resided in the Yangtze River Delta and were diagnosed using sputum or bronchial lavage fluid and hospitalized in Shanghai Pulmonary Hospital from March 2017 to February 2019. The clinical data of confirmed patients were collected. Among the 513 cases of NTM-PD, 482 cases were infected by four common bacteria: Mycobacterium intracellulare (224, 46.5%), M. abscessus (138, 28.6%), M. kansasii (84, 17.4%), and M. avium (36, 7.5%). The analysis found that different NTM strains have their corresponding positive and negative correlation factors (p < 0.05). M. intracellulare, M. abscessus, M. kansasii, and M. avium were the main pathogenic bacteria isolated from patients with NTM-PD in the Yangtze River Delta were. Different strains resulted in different clinical features, assisting in the early diagnosis and treatment of NTM-PD.

Genetic Underpinnings of Carotenogenesis and Light-Induced Transcriptome Remodeling in the Opportunistic Pathogen Mycobacterium kansasii

Mycobacterium kansasii (Mk) causes opportunistic pulmonary infections with tuberculosis-like features. The bacterium is well known for its photochromogenicity, i.e., the production of carotenoid pigments in response to light. The genetics defining the photochromogenic phenotype of Mk has not been investigated and defined pigmentation mutants to facilitate studies on the role of carotenes in the bacterium's biology are not available thus far. In this study, we set out to identify genetic determinants involved in Mk photochromogenicity. We screened a library of ~150,000 transposon mutants for colonies with pigmentation abnormalities. The screen rendered a collection of ~200 mutants. Each of these mutants could be assigned to one of four distinct phenotypic groups. The insertion sites in the mutant collection clustered in three chromosomal regions. A combination of phenotypic analysis, sequence bioinformatics, and gene expression studies linked these regions to carotene biosynthesis, carotene degradation, and monounsaturated fatty acid biosynthesis. Furthermore, introduction of the identified carotenoid biosynthetic gene cluster into non-pigmented Mycobacterium smegmatis endowed the bacterium with photochromogenicity. The studies also led to identification of MarR-type and TetR/AcrR-type regulators controlling photochromogenicity and carotenoid breakdown, respectively. Lastly, the work presented also provides a first insight into the Mk transcriptome changes in response to light.

Non-tuberculous mycobacterial thoracic osteomyelitis in an immunocompetent host: a rare presentation of Mycobacterium kansasii

An immunocompetent man in his 40s presented with 3 months of mid-thoracic back pain which progressed to include progressive paraesthesias and lower extremity weakness. Investigations revealed thoracic spine osteomyelitis with signs of cord compression. He underwent neurosurgical intervention, including laminectomy, spinal cord decompression and partial resection of an epidural mass. Initial intraoperative biopsy and surgical pathology results were concerning for an acid-fast bacillus as the causative pathogen, and the patient was given empiric therapy for presumed Mycobacterium tuberculosis However, microbiology speciation revealed the presence of the non-tuberculous mycobacterium (NTM) Mycobacterium kansasii, which resulted in an alteration of his antimicrobial therapy. This case highlights the importance of considering NTM as a possible aetiology of spinal osteomyelitis, even among immunocompetent individuals or in low-prevalence regions.

Post Surgical Non-tuberculous Mycobacterium: A Case Series

Background

There has been an increase in non-tuberculous mycobacteria (NTM) infection reports in humans. Surgeons are concerned about the link between them and surgical site infections. As a result, it has been challenging to determine just how common this illness is. A two-year study by the authors examines the occurrence of NTM infections after different surgical procedures.

Design and methods

Researchers at a tertiary care hospital in central India performed this prospective study over two years. NTM was found in six of the 25 instances of post-surgical wound infections. Ziehl-Neelsen staining, Auramine O-Rhodamine fluorescence staining, Multiplex Real-Time PCR, and Genotyping were used to identify the species.

Results

M. fortuitum, M. chelonae and M.kansasii were isolated from discharge in 2 cases each respectively. NTM isolates evaluated for antibiotic susceptibility pattern were all sensitive to Clarithromycin (100%). One case with prolonged healing had to be intervened with amikacin along with clarithromycin.

Conclusion

NTM is an infection of uncommon nature which can occur following surgical procedures. Identification of these organisms through sensitive techniques and appropriate therapeutic regimen formulation must be done to tackle this growing menace in health care setups. 

Clinical and Microbiological Characteristics of Mycobacterium kansasii Pulmonary Infections in China

Mycobacterium kansasii, an important opportunistic pathogen of humans, causes serious pulmonary disease. Sixty M. kansasii isolates were collected for investigating the clinical characteristics of patients with M. kansasii infections as well as drug susceptibility and genotypes of M. kansasii. More than 90% of the patients infected with M. kansasii were from eastern China. According to the internal transcribed spacers (ITS), rpoB, hsp65, and tuf, all M. kansasii isolates were classified as molecular type I, irrespective of the disease manifestation. Sixty M. kansasii isolates from China were diverse and separated into four branches. Pairwise average nucleotide identity (ANI) values for M. kansasii isolates affiliated with different genotypes were more than 85%. The earliest isolate was isolated from Jiangsu in 1983. Of the isolates, 78.3% (47/60) were isolated since 1999. All isolates were sensitive to rifabutin. All but one isolate was sensitive to clarithromycin. Sensitivity rates to rifampin, amikacin, moxifloxacin, and linezolid were 80.0%, 90.0%, 88.3%, and 91.7%, respectively. A high rate of resistance was noted for ciprofloxacin (44 isolates, 73.3%) and ethambutol (46 isolates, 76.7%). Compared with M. tuberculosis H37Rv, 12 mutations of embCA were observed in all M. kansasii isolates. All these 60 M. kansasii isolates shared identical sequences of rpoB, inhA, katG, rrl, rrs, rpsL, gyrA, and gyrB. In conclusion, M. kansasii isolates are exhibiting greater genetic diversity globally. The resistance mechanism of M. kansasii is not necessarily related to gene mutation.

IMPORTANCEM. kansasii type I is the main genotype spreading worldwide. The molecular history of the global spread of type I isolates remains largely unclear. We conducted a detailed analysis of genomic evolution of global M. kansasii isolates. Our results suggest that M. kansasii isolates exhibit greater genetic diversity globally.

Antimicrobial Activity of Neutrophils Against Mycobacteria

The mycobacterium genus contains a broad range of species, including the human pathogens M. tuberculosis and M. leprae. These bacteria are best known for their residence inside host cells. Neutrophils are frequently observed at sites of mycobacterial infection, but their role in clearance is not well understood. In this review, we discuss how neutrophils attempt to control mycobacterial infections, either through the ingestion of bacteria into intracellular phagosomes, or the release of neutrophil extracellular traps (NETs). Despite their powerful antimicrobial activity, including the production of reactive oxidants such as hypochlorous acid, neutrophils appear ineffective in killing pathogenic mycobacteria. We explore mycobacterial resistance mechanisms, and how thwarting neutrophil action exacerbates disease pathology. A better understanding of how mycobacteria protect themselves from neutrophils will aid the development of novel strategies that facilitate bacterial clearance and limit host tissue damage.

Huge cutaneous abscess and severe symptomatic hypercalcaemia secondary to Mycobacterium kansasii infection in an immunocompetent patient

Mycobacterium kansasii is among the most common non-tuberculous mycobacteria causing human infections. Apart from pulmonary infection, the most common infection caused by M. kansasii is skin and soft tissue infection, and it is very rare in immunocompetent people. In this report, we present a case of a huge cutaneous abscess caused by M. kansasii A 63-year-old man living in Bangkok presented with progressive pain at the left lateral chest wall for 3 weeks and altered mentation for a few days. Examination revealed a non-tender fluctuated cutaneous mass 20×10 cm in size. An aspiration of the mass yielded 50 mL pus with many positive acid-fast bacilli. Mycobacterial PCR was positive for M. kansasii with culture confirmation. There was severe hypercalcaemia. The treatment included surgical drainage, and medical treatment consisted of isoniazid, rifampicin, ethambutol and levofloxacin, along with adequate hydration and calcitonin for hypercalcaemia. The patient gradually improved and was discharged 12 days after hospitalisation.

Cutaneous Mycobacteriosis Caused by Mycobacterium kansasii in a Yellow-naped Amazon Parrot (Amazona auropalliata)

An approximately 25-year-old, female, yellow-naped Amazon parrot (Amazona auropalliata) was evaluated for a chronic, raised, ulcerative mass on the lateral aspect of the left thigh. Histopathology of an excisional biopsy revealed severe, chronic, multifocal-to-coalescing, ulcerated dermal and subcutaneous granulomas. No infectious organisms were observed on Ziehl-Neelsen or Gomori methenamine silver stains. The parrot was treated with oral sulfamethoxazoletrimethoprim and meloxicam. When reexamined 2 weeks later, the biopsy site had healed. Surgical biopsies were resubmitted 14 months after the original presentation due to recurrence of similar ulcerative lesions on the right leg. Histopathology revealed a similar inflammatory pattern, and hematoxylin-eosin, Ziehl-Neelsen, and silver stains on the biopsy samples were all negative. A Fite-Faraco stain revealed rare acid-fast bacilli throughout the lesion. Tissue polymerase chain reaction test was negative for Mycobacterium avium and Mycobacterium genavense. Mycobacterial culture and subsequent genotyping revealed Mycobacterium kansasii. Mycobacterium kansasii is a significant cause of mycobacteriosis in humans and, therefore, should be considered a potential zoonotic organism. This report describes an unusual primary cutaneous presentation of avian mycobacteriosis.

Population genomics provides insights into the evolution and adaptation to humans of the waterborne pathogen Mycobacterium kansasii

Mycobacterium kansasii can cause serious pulmonary disease. It belongs to a group of closely-related species of non-tuberculous mycobacteria known as the M. kansasii complex (MKC). Here, we report a population genomics analysis of 358 MKC isolates from worldwide water and clinical sources. We find that recombination, likely mediated by distributive conjugative transfer, has contributed to speciation and on-going diversification of the MKC. Our analyses support municipal water as a main source of MKC infections. Furthermore, nearly 80% of the MKC infections are due to closely-related M. kansasii strains, forming a main cluster that apparently originated in the 1900s and subsequently expanded globally. Bioinformatic analyses indicate that several genes involved in metabolism (e.g., maintenance of the methylcitrate cycle), ESX-I secretion, metal ion homeostasis and cell surface remodelling may have contributed to M. kansasii's success and its ongoing adaptation to the human host.

In Vitro Activity of Rifamycin Derivatives against Nontuberculous Mycobacteria, including Macrolide-/Amikacin-Resistant Clinical Isolates

We evaluated the in vitro activity of rifamycin derivatives, including rifampin, rifapentine, rifaximin, and rifabutin, against clinical nontuberculous mycobacteria (NTM) isolates. Of the rifamycin derivatives, rifabutin showed the lowest MICs against all NTM species, including Mycobacterium avium complex, M. abscessus, and M. kansasii Rifabutin also had effective in vitro activity against macrolide- and aminoglycoside-resistant NTM isolates. Rifabutin could be worth considering as a therapeutic option for NTM disease, particularly drug-resistant disease.

Human pathogenic Mycobacterium kansasii (former subtype I) with zoonotic potential isolated from a diseased indoor pet cat, Japan

Nontuberculous mycobacterial (NTM) infections in humans have increased in prevalence in recent decades. Mycobacterium kansasii is one of the most prevalent human pathogenic NTM species worldwide. Herein, we report the first isolation of M. kansasii from an indoor domestic cat in Japan. Comparative genome sequence analysis of the feline isolate showed this pathogen is genetically identical to human pathogenic M. kansasii. This finding suggests that M. kansasii has a potential risk of zoonoses and requires the "One Health" approach to control NTM infection.

Phase II Investigation of the Efficacy of Antimycobacterial Therapy in Chronic Pulmonary Sarcoidosis

Background

A Phase I, single-center investigation found that 8 weeks of antimycobacterial therapy improved sarcoidosis FVC. Safety and efficacy assessments have not been performed in a multicenter cohort.

Research Question

The objective of this study was to determine the safety and efficacy of antimycobacterial therapy on the physiological and immunologic end points of sarcoidosis.

Study Design and Methods

In a double-blind, placebo-controlled, multicenter investigation, patients with pulmonary sarcoidosis were randomly assigned to receive 16 weeks of concomitant levofloxacin, ethambutol, azithromycin, and rifabutin (CLEAR) or matching placebo to investigate the effect on FVC. The primary outcome was a comparison of change in percentage of predicted FVC among patients randomized to receive CLEAR or placebo in addition to their baseline immunosuppressive regimen. Secondary outcomes included 6-min walk distance (6MWD), St. George’s Respiratory Questionnaire (SGRQ) score, adverse events, and decrease in mycobacterial early secreted antigenic target of 6 kDa (ESAT-6) immune responses.

Results

The intention-to-treat analysis revealed no significant differences in change in FVC among the 49 patients randomized to receive CLEAR (1.1% decrease) compared with the 48 randomized to receive placebo (0.02% increase) (P = .64). Physiological parameters such as the change in 6MWD were likewise similar (P = .91); change in SGRQ favored placebo (–8.0 for placebo vs –1.5 for CLEAR; P = .028). The per-protocol analysis revealed no significant change in FVC at 16 weeks between CLEAR and placebo. There was no significant change in 6MWD (36.4 m vs 6.3 m; P = .24) or SGRQ (–2.3 vs –7.0; P = .14). A decline in ESAT-6 immune responses at 16 weeks was noted among CLEAR-treated patients (P = .0003) but not patients receiving placebo (P = .24).

Interpretation

Despite a significant decline in ESAT-6 immune responses, a 16-week CLEAR regimen provided no physiological benefit in FVC or 6MWD among patients with sarcoidosis.

Mitchell J, Lodzinska J, Cazzini P, Varjonen K, Gunn-Moore DA. Systemic Mycobacterium kansasii Infection in Two Related Cats

Mycobacterial infections are a major concern in veterinary medicine because of the difficulty achieving an etiological diagnosis, the challenges and concerns of treatment, and the potential zoonotic risk. Mycobacterium kansasii, a slow-growing non-tuberculous mycobacteria, causes disease in both humans and animals. While infections have been well described in humans, where it may be misdiagnosed as tuberculosis, there are fewer reports in animals. Only four cases have been reported in the domestic cat. This case report describes systemic M. kansasii infection in two sibling indoor-only cats that presented two and half years apart with cutaneous disease that was found to be associated with osteolytic and pulmonary pathology. Infection with M. kansasii was confirmed in both cats by polymerase chain reaction on fine-needle aspirate of a lumbosacral soft tissue mass in one cat and on a tissue punch biopsy of a skin lesion in the other; interferon-gamma release assay inferred M. avium-complex and M. tuberculosis-complex infection in the two cats, respectively. Both patients made a full recovery following antimicrobial therapy with rifampicin, azithromycin, and pradofloxacin (plus N-acetyl cysteine in cat 2). This report highlights successful treatment of systemic M. kansasii mycobacteriosis in the cat and the challenge of accurately diagnosing this infection.

Non-Tuberculous Mycobacteria: Molecular and Physiological Bases of Virulence and Adaptation to Ecological Niches

Non-tuberculous mycobacteria (NTM) are paradigmatic colonizers of the total environment, circulating at the interfaces of the atmosphere, lithosphere, hydrosphere, biosphere, and anthroposphere. Their striking adaptive ecology on the interconnection of multiple spheres results from the combination of several biological features related to their exclusive hydrophobic and lipid-rich impermeable cell wall, transcriptional regulation signatures, biofilm phenotype, and symbiosis with protozoa. This unique blend of traits is reviewed in this work, with highlights to the prodigious plasticity and persistence hallmarks of NTM in a wide diversity of environments, from extreme natural milieus to microniches in the human body. Knowledge on the taxonomy, evolution, and functional diversity of NTM is updated, as well as the molecular and physiological bases for environmental adaptation, tolerance to xenobiotics, and infection biology in the human and non-human host. The complex interplay between individual, species-specific and ecological niche traits contributing to NTM resilience across ecosystems are also explored. This work hinges current understandings of NTM, approaching their biology and heterogeneity from several angles and reinforcing the complexity of these microorganisms often associated with a multiplicity of diseases, including pulmonary, soft-tissue, or milliary. In addition to emphasizing the cornerstones of knowledge involving these bacteria, we identify research gaps that need to be addressed, stressing out the need for decision-makers to recognize NTM infection as a public health issue that has to be tackled, especially when considering an increasingly susceptible elderly and immunocompromised population in developed countries, as well as in low- or middle-income countries, where NTM infections are still highly misdiagnosed and neglected.

Detection of Mycobacterium kansasii using a combination of loop-mediated isothermal amplification (LAMP) and lateral flow biosensors

Mycobacterium kansasii is an opportunistic pathogen that causes both intrapulmonary and extrapulmonary infections. The symptoms of the pulmonary diseases caused by M. kansasii closely resemble Mycobacterium tuberculosis. Rapid and accurate differentiation of M. kansasii from M. tuberculosis, as well as other mycobacteria, is crucial for developing effective therapeutics and disease treatment. In this study, we combined loop-mediated isothermal amplification (LAMP) with lateral flow biosensors (LFB) to detect M. kansasii, by targeting the species-specific sequence of rpoB, a gene which encodes the β subunit of bacterial RNA polymerase. The assay was validated to ensure that it was highly selective by testing M. kansasii, M. tuberculosis, other species of respiratory bacteria, and other nontuberculous mycobacteria. The detection limit of the assay was 1 fg/μL of DNA and 50 CFU of bacilli in sputum. The M. kansasii-LAMP-LFB assay is a fast, cheap, and accurate method for detecting M. kansasii by constant temperature amplification and simple interpretation.

A Rare Case of Brodie's Abscess in HIV Patient Caused by Mycobacterium kansasii

We report a rare case of Brodie's abscess caused by Mycobacterium kansasii (M. kansasii). Our patient is a 39-year-old male who presented with right foot pain a month after a new diagnosis of HIV infection. X-ray and MRI were done, and the diagnosis of Brodie's abscess was confirmed. Surgical debridement was done, and bone cultures grew M. kansasii after five weeks. Brodie's abscess is a subacute form of osteomyelitis usually caused by Staphylococcus. Some other bacteria have been implicated in several case reports. To best of our knowledge, this is the first case of Brodie's abscess caused by M. kansasii. M. kansasii is the atypical mycobacteria causing infections in immunocompromised hosts as in HIV patients with low CD4 count. M. kansasii is usually associated with lung infections with rare extrapulmonary manifestations as in our case.

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.

B Cell-Based Vaccine Transduced With ESAT6-Expressing Vaccinia Virus and Presenting α-Galactosylceramide Is a Novel Vaccine Candidate Against ESAT6-Expressing Mycobacterial Diseases

Early secretory antigenic target-6 (ESAT6) is a potent immunogenic antigen expressed in Mycobacterium tuberculosis as well as in some non-tuberculous mycobacteria (NTM), such as M. kansasii. M. kansasii is one of the most clinically relevant species of NTM that causes mycobacterial lung disease, which is clinically indistinguishable from tuberculosis. In the current study, we designed a novel cell-based vaccine using B cells that were transduced with vaccinia virus expressing ESAT6 (vacESAT6), and presenting α-galactosylceramide (αGC), a ligand of invariant NKT cells. We found that B cells loaded with αGC had increased levels of CD80 and CD86 after in vitro stimulation with NKT cells. Immunization of mice with B/αGC/vacESAT6 induced CD4⁺ T cells producing TNF-α and IFN-γ in response to heat-killed M. tuberculosis. Immunization of mice with B/αGC/vacESAT6 ameliorated severe lung inflammation caused by M. kansasii infection. We also confirmed that immunization with B/αGC/vacESAT6 reduced M. kansasii bacterial burden in the lungs. In addition, therapeutic administration of B/αGC/vacESAT6 increased IFN-γ⁺ CD4⁺ T cells and inhibited the progression of lung pathology caused by M. kansasii infection. Thus, B/αGC/vacESAT6 could be a potent vaccine candidate for the prevention and treatment of ESAT6-expressing mycobacterial infection caused by M. kansasii.

Case Report: Disseminated Mycobacterium kansasii Disease in a Patient with Anti-Interferon-Gamma Antibody

Disseminated nontuberculous mycobacterial (NTM) infections usually occur in severely immunosuppressed patients. These infections may also occur in previously immunocompetent patients with acquired anti-interferon-gamma antibodies (anti-IFN-γ Abs). A previously healthy 33-year-old man presented with a 3-week history of cough and fever. Chest computed tomography showed air-space consolidation in the middle lobe of the right lung and enlargement of the supraclavicular, mediastinal, and hilar lymph nodes. Tissue samples obtained via mediastinoscopy showed granuloma formation with acid-fast bacteria; cultures from the tissue revealed Mycobacterium kansasii. Accordingly, a diagnosis of disseminated M. kansasii disease was made. The positive control tested negative in the QuantiFERON-TB Gold In-tube test, suggesting the presence of anti-IFN-γ Abs. The ELISA test for anti-IFN-γ Abs demonstrated an increased titer. Antimycobacterial drug treatments were initiated after diagnosis. His symptoms improved over 2 months, and he remains well on outpatient management. Disseminated M. kansasii disease is a very rare condition suggestive of immunosuppression. Testing for anti-IFN-γ antibodies might be important in all cases of disseminated M. kansasii disease.

Drug susceptibility profile of Mycobacterium kansasii clinical isolates from Brazil

OBJECTIVES

Mycobacterium kansasii (M. kansasii) pulmonary infection can cause disease with clinical and radiological features similar to tuberculosis. Failure to treat M. kansasii infection is usually associated with resistance; to increase the chance of successful treatment it is important to identify the species and know the susceptibility profile. This study aimed to evaluate the antimycobacterial susceptibility profiles of M. kansasii isolates from Brazil.

METHODS

Sixty-nine M. kansasii isolates from 69 patients were identified by partial sequencing of the hsp65 gene, and their susceptibility profiles were analysed by minimal inhibitory concentration (MIC) assays.

RESULTS

From 69 isolates, 68 showed susceptibility to clarithromycin, amikacin, and moxifloxacin. Most strains showed high rates of resistance to trimethoprim-sulfamethoxazole and ciprofloxacin. Resistance to rifampicin and ethambutol was found in 12% and 25% of isolates, respectively.

CONCLUSIONS

Worrying results were found regarding susceptibility to some drugs used as first-line agents in the treatment of diseases caused by M. kansasii.

Bacterial Diseases

Common marmosets are susceptible to a number of bacterial infections, which may be enzootic, causing sporadic but occasionally severe disease, or which may result in epizootics associated with more severe colony morbidity and mortality. The spectrum of these diseases often differs from those observed in macaque species, and veterinarians caring for common marmosets need to be aware of these unique susceptibilities. In formulating differential diagnoses for sick or diseased animals, it should be recognized that diseases once common in imported animals in the 1960s and 1970s are now rare. It is also important to recognize that housing and sanitation conditions can influence exposure to potentially pathogenic bacteria. In a zoological setting where mixed- or free-ranging exhibits are utilized, animals may be exposed to many more potential pathogens than would be the case in animals raised in a barrier facility.

Predictors of developing Mycobacterium kansasii pulmonary disease within 1 year among patients with single isolation in multiple sputum samples: A retrospective, longitudinal, multicentre study

The clinical significance of a single Mycobacterium kansasii (MK) isolation in multiple sputum samples remains unknown. We conducted this study to evaluate the outcome and predictors of developing MK-pulmonary disease (PD) within 1 year among these patients. Patients with a single MK isolation from ≥3 sputum samples collected within 3 months and ≥2 follow-up sputum samples and chest radiography in the subsequent 9 months between 2008 and 2016 were included. The primary outcome was development of MK-PD within 1 year, with its predictors explored using multivariate logistic regression analysis. A total of 83 cases of a single MK isolation were identified. The mean age was 68.9 ± 17.9, with a male/female ratio of 1.96. Within 1 year, 16 (19%) cases progressed to MK-PD; risk factors included high acid-fast smear (AFS) grade (≥3), elementary occupation workers, and initial radiographic score >6, whereas coexistence with other nontuberculous mycobacterium species was protective. Among patients who developed MK-PD, all experienced radiographic progression, and 44% died within 1 year. Although a single MK isolation does not fulfil the diagnostic criteria of MK-PD, this disease may develop if having above-mentioned risk factors. Early anti-MK treatment should be considered for high-risk patients.

Comparison of latent tuberculosis infection screening strategies before tumor necrosis factor inhibitor treatment in inflammatory arthritis: IGRA-alone versus combination of TST and IGRA

This study aims to compare the latent tuberculosis infection (LTBI) screening strategy of interferon-gamma release assay (IGRA)-alone and in combination with tuberculin skin tests (TSTs) before the initiation of tumor necrosis factor (TNF) inhibitor treatment in patients with inflammatory arthritis. Between January 2011 and June 2017, we enrolled 476 patients who were followed up for ≥1 year after the TNF inhibitor initiation in a tertiary referral center in South Korea. Inflammatory arthritis comprised rheumatoid arthritis in 266 (55.9%) and ankylosing spondylitis in 210 (44.1%) patients. The following strategies were used for LTBI screening during the study period: (i) from January 2011 to October 2014, the combination of TST and QuantiFERON-TB Gold In-Tube (QFT-GIT); (ii) between November 2014 and February 2015, QFT-GIT-alone and (iii) since March 2015, either the combination of TST and QFT-GIT or QFT-GIT-alone depending on the attending physician's choice. We compared the screening strategies of QFT-GIT alone and in combination with TST. Overall, 338 (71.0%) patients received LTBI screening tests using the combination of TST and QFT-GIT, and 138 (29.0%) received QFT-GIT-alone. In addition, the LTBI tests were positive in 159 (47.0%) of 338 patients using the combination tests, and 43.8% (148/338) required LTBI treatment. Meanwhile, the LTBI tests were positive in 32.6% (45/138) of QFT-GIT-alone patients, and 30.4% (42/138) required LTBI treatment. Among 338 patients who received combination tests, 2 patients developed active tuberculosis within 1 year after the TNF inhibitor initiation. Of patients who received QFT-GIT-alone, no patient developed tuberculosis. In conclusion, among patients who received QFT-GIT-alone, the number of patients who required LTBI treatment declined compared to the TST and QFT-GIT combination, and none developed active tuberculosis within 1 year, suggesting that QFT-GIT-alone could be a potential screening strategy for diagnosing LTBI in patients with inflammatory arthritis in South Korea.