Rapidly Growing Nontuberculous Mycobacteria Research Articles

Insight into characteristics and pathogenicity of five rapidly growing non-tuberculous Mycobacterium species isolated from the Siamese fighting fish, Betta splendens

Siamese fighting fish (Betta splendens) play an important role in the global aquarium trade, but their susceptibility to mycobacteriosis could challenge the long-term sustainability of the industry. Thus, this study aimed to characterize rapidly growing non-tuberculous mycobacteria (RGM) isolated from the fish and to investigate their pathogenicity. Five RGM species were investigated, namely Mycobacterium chelonae, M. cosmeticum, M. farcinogenes, M. mucogenicum, and M. senegalense. The isolates were phenotypically and biochemically characterized and assessed for susceptibility to 18 antibiotics and five disinfectants. The pathogenicity of the isolated bacteria was evaluated through experimental infection of the fish by intraperitoneal injection. The results of phenotypic and biochemical typing allowed the identification of some of the isolates and provided preliminary information to distinguish between the bacteria. All isolates were resistant to at least four antibiotics, with multiple antibiotic resistance indexes ranging from 0.22 to 0.61, with M. chelonae having the highest value. Four disinfectants (i.e., ethanol, formalin, chlorine, and povidone‑iodine) showed strong antibacterial activity, whereas potassium permanganate proved less effective. An LD50 value within 7 days showed that M. chelonae had the highest virulence at 7.12 × 105 CFU/fish, followed by M. mucogenicum at 4.25 × 106 CFU/fish and a range of 1.01–1.65 × 107 CFU/fish for the other isolates. Depending on the dose and the isolate administered, some fish displayed acute disease symptoms, while others developed a chronic condition. The acute disease was characterized by short median survival, severe peritonitis, and tissue necrosis. Fish with a chronic infection survived the 42-day trial but were emaciated and had systemic granulomas within their viscera. The findings of this study have not only improved our understanding of the nature of these RGM species but also promoted the development of control strategies to mitigate the negative impact of mycobacteriosis on the Siamese fighting fish industry.

1385. Mechanism-Based, In Vitro Inhibition of Mycobacterium abscessus: Assessing β-Lactam Therapy

Background M. abscessus (Mab) is an emerging pathogen, a highly drug-resistant rapidly-growing nontuberculous mycobacteria. Mab L, D transpeptidases (LdtMab 1–5), D,D carboxypeptidase and BlaMab β-lactamase are important targets. Herein, we tested the susceptibility of ceftaroline (TAR) and imipenem (IMI) alone and in combinations with two diazabicyclooctanone β-lactamase inhibitors (BLI), relebactam (REL) and avibactam (AVI), against representative clinical isolates belonging to the Mab complex and assessed the mechanism of inhibition using mass spectrometry (QTOF-MS)MethodsMinimum inhibitory concentrations (MICs) of TAR and IMI with or without AVI and REL and a TAR-IMI combination with and without REL were determined using microdilution. Approximately 5 x 105 colony-forming units (CFU) per milliliter were inoculated into Middlebrook 7H9 broth supplemented with 10% (vol/vol) oleic albumin dextrose catalase and 0.05% (vol/vol) Tween 80. AVI or REL were added at fixed concentration of 4 µg/mL to serial dilutions of TAR or IMI. For the TAR-IMI combinations, IMI at 1 µg/mL, and serial dilutions of TAR were used. Mab isolates were incubated with test agents at 30°C for 48 h, and MIC was defined as lowest antibiotic concentration that prevented visible bacterial growth. (QTOF-MS) was used to assess intermediates of BlaMab, LdtMab1 and LdtMab2 with TAR, IMI, AVI, and RELResults In-vitro susceptibility testing on representative clinical Mab strains (table). MIC90 was > 128 μg/mL for TAR and 8 μg/mL for IMI. Combination of TAR and IMI lowered MIC’s of all clinical isolates to <0.06 μg/mL. Addition of REL or AVI lowered TAR MICs but had minimal or no impact on IMI or TAR-IMI MICs. Mass spectrometry analyses of BlaMab, LdtMab (1–2) alone and incubated with IMI, TAR, REL and AVI (figure). BlaMab β-lactamase bound the AVI and REL, but acyl complexes with TAR or IMI were not detected. LdtMab (1–2) form stable acyl complexes with AVI, REL, TAR, and IMI.ConclusionAddition of IMI to TAR lowers MICs of TAR against Mab to therapeutically achievable concentrations. It would be welcome news for clinicians who are treating patients with highly resistant Mab infection that the combination of TAR and IMI is commercially available and thus might be considered as part of a rescue regimen. Disclosures All authors: No reported disclosures.

Comparative evaluation of the identification of rapidly growing non-tuberculous mycobacteria by mass spectrometry (MALDI-TOF MS), GenoType Mycobacterium CM/AS assay and partial sequencing of the rpoβ gene with phylogenetic analysis as a reference method

IntroductionThe American Thoracic Society and the Infectious Diseases Society of America recommend that clinically significant non-tuberculous mycobacteria (NTM) should be identified to the species level in order to determine their clinical significance. The aim of this study was to evaluate identification of rapidly growing NTM (RGM) isolated from clinical samples by using MALDI-TOF MS and a commercial molecular system. The results were compared with identification using a reference method. MethodsWe included 46 clinical isolates of RGM and identified them using the commercial molecular system GenoType® CM/AS (Hain, Lifescience, Germany), MALDI-TOF MS (Bruker) and, as reference method, partial rpoβ gene sequencing followed by BLAST and phylogenetic analysis with the 1093 sequences available in the GeneBank. ResultsThe degree of agreement between GenoType® and MALDI-TOF MS and the reference method, partial rpoβ sequencing, was 27/43 (62.8%) and 38/43 cases (88.3%) respectively. For all the samples correctly classified by GenoType®, we obtained the same result with MALDI-TOF MS (27/27). However, MALDI-TOF MS also correctly identified 68.75% (11/16) of the samples that GenoType® had misclassified (p=0.005). ConclusionsMALDI-TOF MS classified significantly better than GenoType®. When a MALDI-TOF MS score >1.85 was achieved, MALDI-TOF MS and partial rpoβ gene sequencing were equivalent. GenoType® was not able to distinguish between species belonging to the M. fortuitum complex. MALDI-TOF MS methodology is simple, rapid and associated with lower consumable costs than GenoType®. The partial rpoβ sequencing methods with BLAST and phylogenetic analysis were not able to identify some RGM unequivocally. Therefore, sequencing of additional regions would be indicated in these cases.

Mycobacterium abscessus and β-Lactams: Emerging Insights and Potential Opportunities.

β-lactams, the most widely used class of antibiotics, are well-tolerated, and their molecular mechanisms of action against many bacteria are well-documented. Mycobacterium abscessus (Mab) is a highly drug-resistant rapidly-growing nontuberculous mycobacteria (NTM). Only in recent years have we started to gain insight into the unique relationship between β-lactams and their targets in Mab. In this mini-review, we summarize recent findings that have begun to unravel the molecular basis for overall efficacy of β-lactams against Mab and discuss emerging evidence that indicates that we have yet to harness the full potential of this antibiotic class to treat Mab infections.

Comparative evaluation of the identification of rapidly growing non-tuberculous mycobacteria by mass spectrometry (MALDI-TOF MS), GenoType Mycobacterium CM/AS assay and partial sequencing of the rpoβ gene with phylogenetic analysis as a reference method

IntroductionThe American Thoracic Society and the Infectious Diseases Society of America recommend that clinically significant non-tuberculous mycobacteria (NTM) should be identified to the species level in order to determine their clinical significance. The aim of this study was to evaluate identification of rapidly growing NTM (RGM) isolated from clinical samples by using MALDI-TOF MS and a commercial molecular system. The results were compared with identification using a reference method. MethodsWe included 46 clinical isolates of RGM and identified them using the commercial molecular system GenoType® CM/AS (Hain, Lifescience, Germany), MALDI-TOF MS (Bruker) and, as reference method, partial rpoβ gene sequencing followed by BLAST and phylogenetic analysis with the 1093 sequences available in the GeneBank. ResultsThe degree of agreement between GenoType® and MALDI-TOF MS and the reference method, partial rpoβ sequencing, was 27/43 (62.8%) and 38/43 cases (88.3%) respectively. For all the samples correctly classified by GenoType®, we obtained the same result with MALDI-TOF MS (27/27). However, MALDI-TOF MS also correctly identified 68.75% (11/16) of the samples that GenoType® had misclassified (p=0.005). ConclusionsMALDI-TOF MS classified significantly better than GenoType®. When a MALDI-TOF MS score >1.85 was achieved, MALDI-TOF MS and partial rpoβ gene sequencing were equivalent. GenoType® was not able to distinguish between species belonging to the M. fortuitum complex. MALDI-TOF MS methodology is simple, rapid and associated with lower consumable costs than GenoType®. The partial rpoβ sequencing methods with BLAST and phylogenetic analysis were not able to identify some RGM unequivocally. Therefore, sequencing of additional regions would be indicated in these cases.

Pacemaker site infection caused by Rapidly Growing Nontuberculous Mycobacteria (RGM)

There has been an increased use of cardiac pacemaker device utilization in cardiac patients with a corresponding increase of device-related infections in these patients. The common cause of postpacemaker implantation infection is either Gram-positive or Gram-negative bacteria. Infection of pacemaker implantation site due to nontuberculous mycobacteria is rare. Globally, thirty-two cases of pacemaker device infections caused by nontuberculous mycobacteria were reported. It is important to carry out not only species identification of mycobacteria but also drug susceptibility testing to start precise treatment to those patients, who are infected with atypical mycobacteria. We report a patient with pacemaker pocket infection due to Mycobacterium chelonae.

Nontuberculosis mycobacterial infections at a specialized tuberculosis treatment centre in the Republic of Korea

BackgroundThe incidence of nontuberculous mycobacteria (NTM) infections is increasing worldwide, however formal evaluations of the epidemiology of NTM infections are limited. Understanding the trends and true prevalence of NTM is a major priority for optimizing infection control programmes and resources. The purpose of this study was to investigate the epidemiology, clinical manifestations, and radiologic findings in NTM-infected patients at specialized Tuberculosis (Tb) treatment centre in South Korea, which is endemic to Tb, and find solutions to control NTM infections.MethodsA retrospective descriptive study was conducted among patients who were diagnosed with NTM from November 2011 to January 2016 at Seoul Metropolitan Government Seobuk hospital, Korea, using medical records and chest radiography results. Prevalence of NTM using national health insurance data was compared to the prevalence and incidence of Tb using National statistics data.ResultsThe age- and sex- adjusted prevalence of NTM infection per 100,000 population increased between 2009 (9.4) and 2016 (36.1). However, the prevalence and incidence of Tb per 100,000 population decreased from 106.5 to 74.4, and 81.2 to 61.8, respectively. In total, 64 patients (37 [57.8%] men) were enrolled in the study. Among 33 (51.6%) patients with slowly growing nontuberculous mycobacteria (SGM) infection, 29 were detected with Mycobacterium avium complex (n = 13, M. avium; n = 16, M. intracellulare), and 4 with M. kansasii. Among 31 (48.4%) patients with rapidly growing nontuberculous mycobacteria (RGM) infection, 27 and 4 patients were detected with M. abscessus complex and M. fortuitum complex, respectively. RGM patients were more likely to have current Tb (P = 0.041), cough (P < 0.05), and sputum (P < 0.01) than SGM patients in the univariate analysis, but not in the multivariate analysis.ConclusionGiven the increasing prevalence of NTM infections, precise epidemiological and surveillance data should be obtained by reporting NTM infections to public health authorities. Introducing nucleic acid amplification tests to differentiate between Tb and NTM in smear-positive specimens should be considered.

Prosthetic Valve Infective Endocarditis With Mycobacterium Fortuitum: Antibiotics Alone Can Be Curative

Rapidly growing non-tuberculous mycobacteria (RGM) are a rare, often fatal cause of infective endocarditis. Although surgery has been the cornerstone of RGM endocarditis therapy, we present the first documented adult case of Mycobacterium fortuitum endocarditis cured with antibiotic therapy.

The Diverse Cellular and Animal Models to Decipher the Physiopathological Traits of Mycobacterium abscessus Infection.

Mycobacterium abscessus represents an important respiratory pathogen among the rapidly-growing non-tuberculous mycobacteria. Infections caused by M. abscessus are increasingly found in cystic fibrosis (CF) patients and are often refractory to antibiotic therapy. The underlying immunopathological mechanisms of pathogenesis remain largely unknown. A major reason for the poor advances in M. abscessus research has been a lack of adequate models to study the acute and chronic stages of the disease leading to delayed progress of evaluation of therapeutic efficacy of potentially active antibiotics. However, the recent development of cellular models led to new insights in the interplay between M. abscessus with host macrophages as well as with amoebae, proposed to represent the environmental host and reservoir for non-tuberculous mycobacteria. The zebrafish embryo has also appeared as a useful alternative to more traditional models as it recapitulates the vertebrate immune system and, due to its optical transparency, allows a spatio-temporal visualization of the infection process in a living animal. More sophisticated immunocompromised mice have also been exploited recently to dissect the immune and inflammatory responses to M. abscessus. Herein, we will discuss the limitations, advantages and potential offered by these various models to study the pathophysiology of M. abscessus infection and to assess the preclinical efficacy of compounds active against this emerging human pathogen.

Isolation of Rapidly Growing Nontuberculous Mycobacteria in Wounds Following Combat-Related Injury.

Rapidly growing nontuberculous mycobacteria (RGNTM) have yet to be described in combat-related injuries. This study investigates the epidemiology, clinical findings, treatment, and outcomes of RGNTM infections among combat casualties wounded in Afghanistan from 2010 to 2012. Patients with RGNTM were identified from the Department of Defense Trauma Registry through the Trauma Infectious Disease Outcomes Study. Trauma history, surgical management, and clinical data were collected. Six isolates from patients requiring antimycobacterial therapy were sequenced. Seventeen cases were identified. Six cases, predominantly associated with Mycobacterium abscessus, required aggressive debridement and a median of 180 days of multidrug antimycobacterial therapy that included clofazimine. M. abscessus isolates expressed the erythromycin resistance methylase (erm(41)) gene for inducible macrolide resistance, yet there were no clinical treatment failures when macrolides were utilized in combination therapy. No clonal similarity between M. abscessus isolates was found. Eleven cases had positive wound cultures, but did not require antimycobacterial therapy. The median duration of time of injury to first detection of a RGNTM was 57 days. This represents the first report of RGNTM infections in war-wounded patients. RGNTM should be recognized as potential pathogens in grossly infected combat wounds. Surgical debridement and multidrug antimycobacterial therapy, when clinically indicated, was associated with satisfactory clinical outcomes.

Pacemaker Infections Caused by Rapidly Growing Non-Tuberculous Mycobacteria: Presentation of Three Cases and Review of the Literature

There has been a rise in the use of cardiac pacemakers and an associated increase in the number of devicerelated infections. Although Staphylococcus aureus and coagulase-negative staphylococci are the most common causes of these infections, rapidly-growing non-tuberculous mycobacteria have occasionally been implicated. We report three cases managed at our institution and review 11 cases found in the literature. Most patients underwent device removal and were managed with more than one antibiotic for at least 4 weeks. All but one patient achieved cure. It is important to recognize these organisms as potential etiologies of pacemaker infections and to request special culture media and stains. Furthermore, antibiotic choice should be guided by susceptibility reports and, at least initially, more than one antibiotic is recommended

Mycobacterium Abscessus Granulomatous Cystitis in a Patient With Superficial Bladder Cancer

Mycobacterium abscessus granulomatous cystitis is exceedingly rare in the literature. However, M. abscessus is the most pathogenic of the rapidly growing nontuberculous mycobacteria (RGM) that is known to cause pulmonary disease, cutaneous infections, and other nosocomial infections. The diagnosis of nonpulmonary disease is made by tissue biopsy or culture. The various nosocomial infections caused by rapidly growing mycobacteria include catheter-related prosthetic devices and surgical site infections. We present the case of a 73-year-old man with superficial bladder cancer, who developed M. abscessus granulomatous cystitis after cystoscopic tumor resection and intravesical bacillus Calmette-Guérin infusions. The patient was successfully treated with levofloxacin and azithromycin.

Mysterious Leg Lesions? Ask About Pedicures

Despite our near-constant exposure to rapidly growing nontuberculous mycobacteria (RGM), which are common colonizers of water supply systems, these organisms seldom make us sick. Or perhaps they do so more often than we recognize. Spurred by two local …

Surgical site infection due to Mycobacterium peregrinum: a case report and literature review

Mycobacterium peregrinum is a species included in the Mycobacterium fortuitum complex, a member of the group of rapidly growing non-tuberculous mycobacteria (RGM). Only a few cases of infection with M. peregrinum have been reported, and no relevant review has been published.Following the treatment of a patient with M. peregrinum infection after plastic surgery, we undertook a review of the literature of previously reported cases of M. peregrinum infection.Ten previously reported cases were identified. Like other cases of the M. fortuitum complex infections, the majority of M. peregrinum infections were related to surgical site infections and catheter-related infections. In the literature, most of the antibiotic regimens were based on a combination of quinolones with various antibiotics, and the duration of treatment ranged from 6 weeks to 4 months.The fact that the optimal treatment for M. peregrinum infection has not yet been established has resulted in the use of a diverse range of therapies. It is important that clinicians carefully review each case so that a more appropriate treatment for M. peregrinum infections can be determined.

Catheter-related bloodstream infections caused by rapidly growing nontuberculous mycobacteria: a case series including rare species

Rapidly growing nontuberculous mycobacteria (RGMs) are responsible for a variety of clinical syndromes in humans including catheter-related blood stream infections (CRBSIs). Recently, we identified a cluster of RGM-associated CRBSI at our institution. We describe the epidemiologic and clinical patterns associated with these infections. We conducted a retrospective single-center review of RGM CRBSI between May 2004 and June 2005. RGMs isolated from blood cultures of 6 patients included Mycobacterium mucogenicum (2), Mycobacterium fortuitum (2), and the rare RGM species, Mycobacterium neoaurum (1) and Mycobacterium septicum (1). All of the patients had a long-term intravascular catheter (mean duration, 6.5 months). Bacteremia was resolved in all patients after catheter removal and appropriate antibiotics. None of the patients suffered a relapse of RGM CRBSI, and all survived to 1 year. RGMs are causative pathogens in both immunosuppressed and immunocompetent individuals with long-term intravascular catheters and blood stream infections. Recent trends at our center suggest that infections with these pathogens are rising.

Atypical Mycobacterium furunculosis occurring after pedicures

Mycobacterium fortuitum complex are rapidly-growing nontuberculous mycobacteria found ubiquitously in the environment including, water, soil, dust, and biofilms. M fortuitum has been reported to cause skin and soft-tissue infections in association with nail salon footbath use during pedicures. Four cases of M fortuitum complex furunculosis are reported that occurred after pedicures in the Cincinnati, Ohio/Northern Kentucky area. Dermatologists and clinicians should consider mycobacterial infections from the M fortuitum complex when patients present with nonhealing furuncles on the lower legs and should inquire about recent pedicures. Early recognition and institution of appropriate therapy are critical. Public health measures should be explored to protect against such infections, given the recent popularity of the nail care industry.

Clinical Manifestations of Pulmonary Infection Due to Rapidly Growing Nontuberculous Mycobacteria

Introduction :R apidly growing nontuberculous mycobacteria (RGM) can produce numerous types of manifestations including a pulmonary infection. Managing a pulmonary infection due to RGM is unusually difficult to treat because the organism is invariably resistant to traditional antituberculous drugs and has a varying susceptibility to other antibiotics. The experiences of treatments for a RGM pulmonary infection with various antibiotics are also limited. This study evaluated the clinical manifestations, treatment, and the therapeutic outcomes of a RGM pulmonary infection. Subjects and method :F ifty-four cases with RGM from respiratory specimens were identified between November of 1996 and September of 2002 in the Asan medical center. The medical records and radiographic findings in 20 patients who fulfilled the diagnostic criteria of nontuberculous mycobacteria (NTM) pulmonary disease by ATS guidelines. The clinical, laboratory, and radiological parameters between subgroups. Results :O f the 20 patients, 15 were female. The mean age was 57.7 yrs (±7.5), and all of the patients had a history of pulmonary tuberculosis. Most (90%) had an underlying lung disease. The

Clinical Manifestations of Pulmonary Infection Due to Rapidly Growing Nontuberculous Mycobacteri

INTRODUCTION: Rapidly growing nontuberculous mycobacteria (RGM) can produce numerous types of infections including cutaneous disease, lymphadenitis, disseminated disease and pulmonary infection. The management of pulmonary infection due to RGM has proved unusually difficult to treat because the organism is invariably resistant to traditional antituberculous drugs and has varying susceptibility to other antibiotics. We evaluated the clinical manifestations, treatment, and therapeutic outcomes of RGM pulmonary infection.