Slow-growing Nontuberculous Mycobacteria Research Articles

Targeting intracellular nontuberculous mycobacteria and M. tuberculosis with a bactericidal enzymatic cocktail.

To address intracellular mycobacterial infections, we developed a cocktail of four enzymes that catalytically attack three layers of the mycobacterial envelope. This cocktail is delivered to macrophages, through a targeted liposome presented here as ENTX_001. Endolytix Cocktail 1 (EC1) leverages mycobacteriophage lysin enzymes LysA and LysB, while also including α-amylase and isoamylase for degradation of the mycobacterial envelope from outside of the cell. The LysA family of proteins from mycobacteriophages has been shown to cleave the peptidoglycan layer, whereas LysB is an esterase that hydrolyzes the linkage between arabinogalactan and mycolic acids of the mycomembrane. The challenge of gaining access to the substrates of LysA and LysB provided exogenously was addressed by adding amylase enzymes that degrade the extracellular capsule shown to be present in Mycobacterium tuberculosis. This enzybiotic approach avoids antimicrobial resistance, specific receptor-mediated binding, and intracellular DNA surveillance pathways that limit many bacteriophage applications. We show this cocktail of enzymes is bactericidal in vitro against both rapid- and slow-growing nontuberculous mycobacteria (NTM) as well as M. tuberculosis strains. The EC1 cocktail shows superior killing activity when compared to previously characterized LysB alone. EC1 is also powerfully synergistic with standard-of-care antibiotics. In addition to in vitro killing of NTM, ENTX_001 demonstrates the rescue of infected macrophages from necrotic death by Mycobacteroides abscessus and Mycobacterium avium. Here, we demonstrate shredding of mycobacterial cells by EC1 into cellular debris as a mechanism of bactericide.IMPORTANCEThe world needs entirely new forms of antibiotics as resistance to chemical antibiotics is a critical problem facing society. We addressed this need by developing a targeted enzyme therapy for a broad range of species and strains within mycobacteria and highly related genera including nontuberculous mycobacteria such as Mycobacteroides abscessus, Mycobacterium avium, Mycobacterium intracellulare, as well as Mycobacterium tuberculosis. One advantage of this approach is the ability to drive our lytic enzymes through encapsulation into macrophage-targeted liposomes resulting in attack of mycobacteria in the cells that harbor them where they hide from the adaptive immune system and grow. Furthermore, this approach shreds mycobacteria independent of cell physiology as the drug targets the mycobacterial envelope while sidestepping the host range limitations observed with phage therapy and resistance to chemical antibiotics.

Impact of Methylthioxylose Substituents on the Biological Activities of Lipomannan and Lipoarabinomannan in Mycobacterium tuberculosis.

Two lipoglycans, lipomannan (LM) and lipoarabinomannan (LAM), play various, albeit incompletely defined, roles in the interactions of mycobacteria with the host. Growing evidence points to the modification of LM and LAM with discrete covalent substituents as a strategy used by these bacteria to modulate their biological activities. One such substituent, originally identified in Mycobacterium tuberculosis (Mtb), is a 5-methylthio-d-xylose (MTX) sugar, which accounts for the antioxidative properties of LAM. The widespread distribution of this motif across Mtb isolates from several epidemiologically important lineages have stimulated interest in MTX-modified LAM as a biomarker of tuberculosis infection. Yet, several lines of evidence indicate that MTX may not be restricted to Mtb and that this motif may substitute more acceptors than originally thought. Using a highly specific monoclonal antibody to the MTX capping motif of Mtb LAM, we here show that MTX motifs not only substitute the mannoside caps of LAM but also the mannan core of LM in Mtb. MTX substituents were also found on the LM and LAM of pathogenic, slow-growing nontuberculous mycobacteria. The presence of MTX substituents on the LM and LAM from Mtb enhances the pro-apoptotic properties of both lipoglycans on LPS-stimulated THP-1 macrophages. A comparison of the cytokines and chemokines produced by resting and LPS-activated THP-1 cells upon exposure to MTX-proficient versus MTX-deficient LM further indicates that MTX substituents confer anti-inflammatory properties upon LM. These findings add to our understanding of the glycan-based strategies employed by slow-growing pathogenic mycobacteria to alter the host immune response to infection.

Genomic diversity and clinical relevance of Mycobacterium simiae.

Mycobacterium simiae is a slow-growing non-tuberculous mycobacterium that can cause non-tuberculous mycobacterium (NTM) pulmonary disease and extrapulmonary infections. Until now, detailed genomic and clinical characteristics, as well as possible transmission routes of this rare pathogen remain largely unknown. We conducted whole genome sequencing of available M. simiae isolates collected at a tertiary care centre in Central Germany from 2006 to 2020 and set them into context with publicly available M. simiae complex sequences through phylogenetic analysis. Resistance, virulence and stress genes, as well as known Mycobacteriaceae plasmid sequences were detected in whole genome raw reads. Clinical data and course were retrieved and correlated with genomic data. We included 33 M. simiae sensu stricto isolates from seven patients. M. simiae showed low clinical relevance with only two patients fulfilling American Thoracic Society (ATS) criteria in our cohort and three receiving NTM-effective therapy. The bacterial populations were highly stable over time periods of up to 14 years, and no instances of mixed or re-infections with other strains of M. simiae were observed. Clustering with <12 single nucleotide polymorphisms distance was evident among isolates from different patients; however, proof for human-to-human transmission could not be established from epidemiological data. Overall, the available sequence data for M. simiae complex was significantly extended and new insights into its pathogenomic traits were obtained. We demonstrate high longitudinal genomic stability within single patients. Although we cannot exclude human-to-human transmission, we consider it unlikely in the light of available epidemiological data.

Mycobacterium chimaera Infections in a Unit of Cardio Surgery: Study at a General Hospital in Padua, Italy.

Mycobacterium chimaera is a slow-growing non-tuberculous mycobacterium already known for being able to colonize cardio surgery heater-cooler units (HCUs). This study aims to describe the real magnitude of the phenomenon, providing a methodological protocol and the results of a longitudinal survey. In the period 1 January 2017-23 May 2022, over 1191 samples were collected on 35 HCUs of two different manufacturers. Among them, we identified 118 (10.3%) positive results for M. chimaera. We propose our 4-year biosurveillance experience as a practical model to minimize microbiological patients' risk, suggesting the need for new procedures and interventions for a safer and more ecological cardio surgery.

Radiological Features of Changes in the Lungs Caused by Fast- or Slow-Growing Nontuberculous Mycobacteria

Objective: to compare radiological features of pulmonary nontuberculous mycobacterioses (NTM) caused by fast- or slow-growing mycobacteria.Material and methods. Radiological features of the disease were studied in 110 patients with newly diagnosed NTM. The patients were divided into two groups: 70 (63.6%) patients with slow-growing NTM and 40 (36.3%) with fast-growing NTM. The diagnosis was based on patient’s complaints, specified case history, radiological studies, clinical laboratory studies, sputum smear studies, bronchoalveolar lavage studies, different types of bronchial biopsies, and video-assisted thoracoscopic surgery resection samples. According to the results of high-resolution computed tomography (HRCT), a comparative analysis of the degree of involvement in the pathological process of such anatomical formations as parenchyma and stroma, vessels, bronchi, pleura and intrathoracic lymph nodes was carried out.Results. The analysis of HRCT studies showed that fast-growing NTM is not characterized by gross deformation of bronchopulmonary structures. There is a more pronounced infiltrative phase with the involvement of vessels, pleura and bronchial lesions of smaller generations, the formation of broncho-bronchiolectasias and symptoms of bronchiolitis, faster clinical and radiological involution under dynamic observation. Slow-growing NTM is characterized by a more severe deformation of bronchopulmonary structures with the formation of different-sized bronchiectasis, bronchogenic cavities, a more torpid course of the inflammatory process.Conclusion. Despite the similarities of clinical and radiological patterns of NTM, we established some distinguished features for slow-growing and fast-growing types.

Comparative genomic analysis reveals differential genomic characteristics and featured genes between rapid- and slow-growing non-tuberculous mycobacteria.

Non-tuberculous mycobacteria (NTM) is a major category of environmental bacteria in nature that can be divided into rapidly growing mycobacteria (RGM) and slowly growing mycobacteria (SGM) based on their distinct growth rates. To explore differential molecular mechanisms between RGM and SGM is crucial to understand their survival state, environmental/host adaptation and pathogenicity. Comparative genomic analysis provides a powerful tool for deeply investigating differential molecular mechanisms between them. However, large-scale comparative genomic analysis between RGM and SGM is still uncovered. In this study, we screened 335 high-quality, non-redundant NTM genome sequences covering 187 species from 3,478 online NTM genomes, and then performed a comprehensive comparative genomic analysis to identify differential genomic characteristics and featured genes/protein domains between RGM and SGM. Our findings reveal that RGM has a larger genome size, more genes, lower GC content, and more featured genes/protein domains in metabolism of some main substances (e.g. carbohydrates, amino acids, nucleotides, ions, and coenzymes), energy metabolism, signal transduction, replication, transcription, and translation processes, which are essential for its rapid growth requirements. On the other hand, SGM has a smaller genome size, fewer genes, higher GC content, and more featured genes/protein domains in lipid and secondary metabolite metabolisms and cellular defense mechanisms, which help enhance its genome stability and environmental adaptability. Additionally, orthogroup analysis revealed the important roles of bacterial division and bacteriophage associated genes in RGM and secretion system related genes for better environmental adaptation in SGM. Notably, PCoA analysis of the top 20 genes/protein domains showed precision classification between RGM and SGM, indicating the credibility of our screening/classification strategies. Overall, our findings shed light on differential underlying molecular mechanisms in survival state, adaptation and pathogenicity between RGM and SGM, show the potential for our comparative genomic pipeline to investigate differential genes/protein domains at whole genomic level across different bacterial species on a large scale, and provide an important reference and improved understanding of NTM.

Risk of zoonoses involving slow-growing non-tuberculous mycobacteria: Survey of antimicrobial resistance among strains from domestic and wild animals

Non-tuberculous mycobacteria are opportunistic pathogens that cause disease mainly in immunocompromised hosts. The present study assessed the prevalence of antibiotic resistance among such mycobacteria from domestic and wild animals in Croatia sampled during several years within a national surveillance program. A total of 44 isolates belonging to nine slow-growing species were genotyped and analyzed for susceptibility to 13 antimicrobials often used to treat non-tuberculous mycobacterial infections in humans. Most prevalent resistance was to moxifloxacin (77.3%), doxycycline (76.9%), and rifampicin (76.9%), followed by ciprofloxacin (65.4%), trimethoprim-sulfamethoxazole (65.4%), and linezolid (61.4%). Few isolates were resistant to rifabutin (7.7%) or amikacin (6.8%). None of the isolates was resistant to clarithromycin. Nearly all isolates (86.4%) were resistant to multiple antibiotics. Our findings suggest substantial risk that human populations may experience zoonotic infections with non-tuberculous mycobacteria that will be difficult to treat using the current generation of antibiotics. Future work should clarify how resistance emerges in wild populations of non-tuberculous mycobacteria.

Pseudo-outbreak of Mycobacterium lentiflavum at a general hospital in Japan.

Mycobacterium lentiflavum is a slow-growing nontuberculous mycobacterium that is widely distributed in soil and water systems, but it is sometimes pathogenic to humans. Although cases of M. lentiflavum infections are rare, 22 isolates of M. lentiflavum were identified at a single hospital in Japan. We suspected a nosocomial outbreak; thus, we conducted transmission pattern and genotype analyses. Cases of M. lentiflavum isolated at Kushiro City General Hospital in Japan between May 2020 and April 2021 were analyzed. The patient samples and environmental culture specimens underwent whole-genome sequencing (WGS). Additionally, we retrospectively collected clinical data from patient medical records. Altogether, 22 isolates of M. lentiflavum were identified from sputum and bronchoalveolar lavage samples. Clinically, the instances with M. lentiflavum isolates were considered contaminants. In the WGS analysis, 19 specimens, including 18 patient samples and 1 environmental culture from the hospital's faucet, showed genetic similarity. The frequency of M. lentiflavum isolation decreased after we prohibited the use of taps where M. lentiflavum was isolated. WGS analysis identified that the cause of M. lentiflavum pseudo-outbreak was the water used for patient examinations, including bronchoscopy.

Complete Genome and Partial Megaplasmid Sequences of Mycobacterium pseudoshottsii Strain NJB1907-Z4, Isolated from an Aquarium-Reared Japanese Sardine (Sardinops melanostictus) in Japan.

Mycobacterium pseudoshottsii, a slow-growing nontuberculous mycobacterium, has been isolated from wild and cultured fish. We report here the complete genome and partial megaplasmid sequences of a strain isolated from an aquarium-reared Japanese sardine (Sardinops melanostictus) in Japan, M. pseudoshottsii NJB1907-Z4.

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

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

A refractory tenosynovitis of the wrist: a case report

BackgroundMycobacterium malmoense is a species of slow-growing nontuberculous mycobacteria. It causes mostly pulmonary infections or lymphadenitis in children, but is increasingly encountered in isolated tenosynovitis in adults. Diagnosis is often delayed because of the rarity of the condition and the difficulty of culturing the bacteria.Case presentationWe report on a rare association of seronegative polyarthritis with infectious nontuberculous mycobacteria tenosynovitis. A 65-year-old Caucasian female was referred to our clinic because of persisting tenosynovitis of the finger flexor tendons of her right hand, despite two previous synovectomies. She also reported bilateral shoulder and left wrist pain. Paraclinical investigations showed slightly elevated inflammatory parameters. Ultrasound showed synovitis of metacarpophalangeal joints of the right hand and right knee, and a bilateral subacromial bursitis. Hand magnetic resonance imaging also revealed an erosive carpal synovitis. Bacteriological analysis of the second tenosynovectomy specimen showed no growths in aerobic and anaerobic cultures. An additional synovial fluid analysis of the wrist joint was negative for mycobacteria and crystals. Seronegative polyarthritis was suspected, but the initiated immunosuppressive treatment with prednisolone and methotrexate resulted in no clinical improvement of the tenosynovitis. Yet the other joints responded well, and the inflammatory parameters normalized. The immunosuppression was later stopped because of side effects. Due to massive worsening of the tenosynovitis, a third synovectomy was performed. Mycobacterium malmoense was identified on biopsy, leading to the diagnosis of infectious tenosynovitis. At this point, we started an antituberculous therapy, with incomplete response. A combination of antimicrobial and immunosuppressive treatment finally led to the desired clinical improvement.ConclusionThe treatment of nontuberculous mycobacteria tenosynovitis is not well established, but combining antibiotics with surgical debridement is probably the most adequate approach. Our case highlights the importance of having a high clinical suspicion of an atypical infection in patients with inflammatory tenosynovitis not responding to usual care.

Genetic diversity of nontuberculous mycobacteria among symptomatic tuberculosis negative patients in Kenya.

Non-Tuberculous Mycobacteria (NTM) transmission to humans occurs through inhalation of dust particles or vaporized water containing NTM leading to pulmonary manifestations. NTM infections are often misdiagnosed for tuberculosis (TB) due to their similar clinical and radiological manifestations. We, therefore, performed a species-level identification of NTM in symptomatic TB negative patients through sequencing of the hsp65 gene. We conducted a cross-sectional study at the National Tuberculosis Reference Laboratory in the period between January to November 2020. One hundred and sixty-six mycobacterial culture-positive samples that tested negative for TB using capilia underwent Polymerase Chain Reaction targeting the hsp65 gene. Isolates showing a band with gel electrophoresis at 441 bp position were sequenced using Sanger technology. Geneious software was used to analyze the obtained sequences, and the National Center for Biotechnology Information gene database identified NTM species for each isolate. A phylogenetic tree was constructed from the DNA sequences and evolutionary distances computed using the general time-reversible method. Pearson chi-square was used to determine the association between NTM infection and participants' characteristics. Our study identified 43 different NTM species. The dominant NTM belonged to Mycobacterium avium complex 37 (31%). Slow-growing NTM were the majority at 86 (71%) while rapid-growing NTM were 36 (29%). A significant association (P<0.05) was observed for regions and age, while patient type had a weak likelihood of NTM infection. Our study characterized the diversity of NTM in Kenya for the first time and showed that species belonging to M. Avium Complex are the most prevalent in the country.

Mycobacterium Abscessus HelR Interacts with RNA Polymerase to Confer Intrinsic Rifamycin Resistance

Bacterial RNA polymerase is a target of the potent and broad-spectrum rifamycin group of antibiotics. Mutations within rpoB and inactivation by a diverse group of enzymes constitute the most widespread mechanisms of resistance. Rifampicin (RIF) constitutes the frontline therapy against M. tuberculosis as well as most slow-growing non-tuberculous mycobacteria (NTM) but is completely ineffective against M. abscessus. This high level of RIF resistance is despite the absence of mutations in the rifampicin resistance determining region of Mab_rpoB and is partially attributed to the presence of an ADP-ribosyltransferase (Arr) activity that inactivates RIF. Rifabutin (RBT), a close analogue of RIF, has recently been shown to be effective against M. abscessus in vitro and in a mouse model and comprises a promising therapeutic against M. abscessus infections. Using RNA sequencing we show that exposure of M. abscessus to sublethal doses of RIF and RBT results in ~25-fold upregulation of Mab_ helR in laboratory and clinical isolates; an isogenic deletion mutant of Mab_ helR is hypersensitive to RIF and RBT, and over-expression of Mab_ helR confers RIF tolerance in M. tuberculosis implying that Mab_helR constitutes a significant determinant of inducible RIF and RBT resistance. We demonstrate a preferential association of MabHelR with RNA polymerase in vivo in bacteria exposed to RIF and show that purified MabHelR can rescue transcription inhibition in the presence of RIF in in vitro transcription assays. Furthermore, MabHelR can dissociate RNAP from RIF-stalled initiation complexes in vitro, a species we envisage accumulates upon RIF exposure. Lastly, we show that the tip of the PCh-loop of Mab_ helR, in particular residues E496 and D497 that are in proximity to RIF, is critical for conferring RIF resistance without being required for dissociation of antibiotic-stalled RNAP complexes. This suggests that HelR may be additionally involved in displacing RIF bound to RNAP and function as an RNAP protection protein.

Biofilm formation in the lung contributes to virulence and drug tolerance of Mycobacterium tuberculosis

Tuberculosis is a chronic disease that displays several features commonly associated with biofilm-associated infections: immune system evasion, antibiotic treatment failures, and recurrence of infection. However, although Mycobacterium tuberculosis (Mtb) can form cellulose-containing biofilms in vitro, it remains unclear whether biofilms are formed during infection in vivo. Here, we demonstrate the formation of Mtb biofilms in animal models of infection and in patients, and that biofilm formation can contribute to drug tolerance. First, we show that cellulose is also a structural component of the extracellular matrix of in vitro biofilms of fast and slow-growing nontuberculous mycobacteria. Then, we use cellulose as a biomarker to detect Mtb biofilms in the lungs of experimentally infected mice and non-human primates, as well as in lung tissue sections obtained from patients with tuberculosis. Mtb strains defective in biofilm formation are attenuated for survival in mice, suggesting that biofilms protect bacilli from the host immune system. Furthermore, the administration of nebulized cellulase enhances the antimycobacterial activity of isoniazid and rifampicin in infected mice, supporting a role for biofilms in phenotypic drug tolerance. Our findings thus indicate that Mtb biofilms are relevant to human tuberculosis.

Drug susceptibility distributions of Mycobacterium chimaera and other non-tuberculous mycobacteria.

Recent outbreaks of cardiac surgery-associated Mycobacterium chimaera infections have highlighted the importance of species differentiation within the Mycobacterium avium complex and pointed to a lack of antibiotic susceptibility data for M. chimaera Using the MGIT 960/EpiCenter TB eXiST platform, we have determined antibiotic susceptibility patterns of 48 clinical M. chimaera isolates and 139 other non-tuberculous mycobacteria including 119 members of the M. avium complex and 20 Mycobacterium kansasii towards clofazimine and other drugs used to treat infections with slowly growing nontuberculous mycobacteria (NTM). MIC50, MIC90 and tentative epidemiological cutoff (ECOFF) values for clofazimine were 0.5 mg/L, 1 mg/L and 2 mg/L for M. chimaera. Comparable values were observed for other M. avium complex members, lower MIC50 (≤0.25 mg/L), MIC90 (0.5 mg/L) and ECOFF (1 mg/L) values were found for M. kansasii Susceptibility to clarithromycin, ethambutol, rifampin, rifabutin, amikacin, moxifloxacin and linezolid was in general similar for M. chimaera and other members of the M. avium complex but increased for M. kansasii The herein determined MIC distributions, MIC90 and ECOFF values of clofazimine for M. chimaera and other NTM provide the basis for the definition of clinical breakpoints. Further studies are needed to establish correlation of in vitro susceptibility and clinical outcome.

Characterization of Biofilm Formation by Mycobacterium chimaera on Medical Device Materials.

Non-tuberculous mycobacteria (NTM) are widespread in the environment and are a public health concern due to their resistance to antimicrobial agents. The colonization of surgical heater-cooler devices (HCDs) by the slow-growing NTM species Mycobacterium chimaera has recently been linked to multiple invasive infections in patients worldwide. The resistance of M. chimaera to antimicrobials may be aided by a protective biofilm matrix of extracellular polymeric substances (EPS). This study explored the hypothesis that M. chimaera can form biofilms on medically relevant materials. Several M. chimaera strains, including two HCD isolates, were used to inoculate a panel of medical device materials. M. chimaera colonization of the surfaces was monitored for 6 weeks. M. chimaera formed a robust biofilm at the air-liquid interface of borosilicate glass tubes, which increased in mass over time. M. chimaera was observed by 3D Laser Scanning Microscopy to have motility during colonization, and form biofilms on stainless steel, titanium, silicone and polystyrene surfaces during the first week of inoculation. Scanning electron microscopy (SEM) of M. chimaera biofilms after 4 weeks of inoculation showed that M. chimaera cells were enclosed entirely in extracellular material, while cryo-preserved SEM samples further revealed that an ultrastructural component of the EPS matrix was a tangled mesh of 3D fiber-like projections connecting cells. Considering that slow-growing M. chimaera typically has culture times on the order of weeks, the microscopically observed ability to rapidly colonize stainless steel and titanium surfaces in as little as 24 h after inoculation is uncharacteristic. The insights that this study provides into M. chimaera colonization and biofilm formation of medical device materials are a significant advance in our fundamental understanding of M. chimaera surface interactions and have important implications for research into novel antimicrobial materials, designs and other approaches to help reduce the risk of infection.

Review of the international clinical practice guidelines for the treatment of lung infections caused by nontuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) include more than 190 species and subspecies. Some NTM species can cause human diseases of the lungs or extrapulmonary infections. The guidelines focus on pulmonary mycobacteriosis in adult patients without cystic fibrosis or HIV infection caused by the most common NTMs, such as Mycobacterium avium complex, Mycobacterium kansasii, and Mycobacterium xenopi among slow-growing NTMs and Mycobacterium abscessus complex among fast-growing species. Experts of American Thoracic Society (ATS), European Respiratory Society (ERS), European Society for Clinical Microbiology and Infectious Diseases (ESCMID), and American Society for Infectious Diseases (IDSA) contributed to the development of the guidelines. A total of 31 evidence-based recommendations are provided for the diagnosis and treatment of NTM-induced lung infections.

Mycobacterium xenopi osteomyelitis of the spine: a case report

ABSTRACT BACKGROUND: Mycobacterium xenopi (M. xenopi) osteomyelitis is an uncommon infection which is found in immunosuppressed patients. It is reported to be a slow-growing, nonchromogenic or scotochromogenic nontuberculous mycobacterium. The lungs constitute the most common site for infection and extrapulmonary manifestations, and disseminated forms of the disease are rare. Only a few cases of spontaneous spinal involvement have been reported. We report a case of M. xenopi vertebral osteomyelitis of the spine PATIENT AND METHODS: A 41-year-old female patient, HIV reactive on antiretroviral therapy with a low CD4 count of 183 cells/mm3, presented with clinical and radiological features in keeping with thoracic spinal tuberculosis, complicated with thoracic myelopathy. She was managed surgically with costo-transversectomy and drainage of the paraspinal cold abscess. The Ziehl-Neelsen staining was negative for acid-fast bacilli. However, the histology result revealed a necrotising granulomatous inflammation. A delayed result of polymerase chain reaction (PCR)/line probe assay for Mycobacterium genus testing revealed the presence of M. xenopi, as the cause for the spine osteomyelitis and thoracic myelopathy. However, no M. xenopi susceptibility testing, and no specific photoreactivity techniques for strain identification, were performed. Anti-tuberculosis therapy (ATT) consisting of a two-month initiation phase using rifampicin, isoniazid, ethambutol and pyrazinamide, followed by a seven-month continuation phase using rifampicin and isoniazid, was initiated according to national guidelines. She was fitted with a thoraco-lumbar-sacral orthosis, and underwent a spinal rehabilitation programme. Upon receipt of the PCR result, and considering the good clinical and radiological response to ATT, a consensus was reached with the Infectious Disease Unit (IDU) to continue with ATT until 18 months due to the atypical nature of the pathogen. RESULTS: The patient was successfully treated with the standard TB regimen, but for a period of 18 months, and made full clinical neurological recovery, without any back pain. Furthermore, her CD4 count had also improved to 707 cells/mm3 with a viral load reported lower than 1 000 copies/ml CONCLUSION: This case report emphasises the importance of biopsy in suspected spinal tuberculosis and highlights the concerns with laboratory testing and the prognostic and therapeutic implications of a positive strain identification Level of evidence: Level 5 Keywords: Mycobacterium xenopi osteomyelitis, tuberculosis, anti-tuberculosis treatment

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.

Longest incubation period of Mycobacterium chimaera infection after cardiac surgery.

Mycobacterium chimaera infections have been associated with contamination of a heater-cooler unit used during cardiopulmonary bypass procedures since 2006. Mycobacterium chimaera is a slow-growing non-tuberculous mycobacterium responsible for an infection, which is difficult to treat and has often a devastating course. Until now, M. chimaera infection has been shown to occur up to 8 years after operation. We report a patient presenting with an aortic pseudoaneurysm who developed M. chimaera infection 12 years after repair of an acute type A aortic dissection with graft replacement of the ascending aorta and stent-grafting of the arch. As far as we know, this is the case with the longest incubation period of M. chimaera infection. The present experience indicates that all patients who underwent open heart procedures since 2006 with such heater-cooler unit model should be closely followed up regardless of time of index surgery.