Rapidly Growing Mycobacteria

Modulatory activity of piperine on clarithromycin against rapidly growing mycobacteria

The treatment of mycobacteriosis depends on the species causing the disease and its susceptibility to drugs. Clarithromycin represents the cornerstone of regimens for fast-growing non-tuberculous mycobacteria, due to its antimicrobial and immunomodulatory properties. Coadministration with an adjuvant compound could decrease the minimum inhibitory concentration of antimicrobials in cases of resistant bacilli. Our focus was to combine clarithromycin with piperine, a natural compound with several biological activities already described. We determined the in vitro extra- and intracellular activity of clarithromycin, piperine and the combination against clinical isolates of fast-growing non-tuberculous mycobacteria. Piperine was shown to modulate the activity of the antimicrobial in vitro by up to 16 times at the extracellular level, including against clinical isolates phenotypically resistant to clarithromycin. The bacteriostatic activity of clarithromycin was prolonged when combined with piperine for 96 h in the time-kill curve assay. Furthermore, in an intramacrophage environment, there was a modest improvement in the activity of the combination which could be explained by the fact that the action of piperine facilitates the entry of the antimicrobial into macrophages. This leads us to believe that the use of piperine as a possible candidate for adjuvant therapy with clarithromycin for the treatment of mycobacteriosis caused by fast-growing species could prevent the appearance of resistant isolates and thus increase the chances of curing these patients.

Trends in nontuberculous mycobacterial disease mortality based on 2000-2022 data from 83 countries

OBJECTIVE

To examine the international trends for nontuberculous mycobacterial-associated mortality rates, as nontuberculous mycobacterial infections are becoming increasingly prevalent and pose a significant public health challenge, especially in older populations.

METHODS

This retrospective observational study used data from the World Health Organization mortality database, which included patients with nontuberculous mycobacterial infection in 83 countries. We stratified the data by sex, age, and geographic region and calculated crude and age-standardized mortality rates to estimate long-term mortality trends.

RESULTS

In total, 42,182 nontuberculous mycobacterial infection-associated deaths (58.1% in women) were reported in 83 countries between 2000 and 2022. The locally weighted regression model estimation for the nontuberculous mycobacterial infection-associated mortality rate more than doubled-from 0.36 deaths per 1,000,000 individuals in 2000 to 0.77 deaths per 1,000,000 individuals in 2022. Eighty-six percent of nontuberculous mycobacterial infection-associated deaths occurred in people aged ≥65 years. The mortality rate was the highest in the Western Pacific Region.

CONCLUSIONS

This study highlights the impact of emerging nontuberculous mycobacterial diseases and the importance of targeted interventions for managing and reducing mortality, particularly in vulnerable older populations. Further studies are warranted to determine the factors contributing to geographical disparity and treatment options.

Nontuberculous Mycobacterial Pneumonia Caused by Mycobacterium immunogenum: A Case Report and Literature Review

Background

Mycobacterium immunogenum is a rare nontuberculous mycobacterium belonging to the Mycobacterium chelonae-abscessus group. Most cases reported in the past decade have been extrapulmonary infections, and reports of nontuberculous mycobacterial pulmonary disease (NTM-PD) caused by M. immunogenum are rare. Herein, we report a case of NTM-PD caused by M. immunogenum.

Case Presentation

An 81-year-old man with a history of chronic kidney disease and cardiovascular disease was hospitalised in 2021 owing to pneumonia. Two sputum cultures tested positive for Mycobacterium. The mycobacterium biochip test identified M. abscessus and Mycobacterium gilvum, and whole-genome sequencing confirmed the identity as M. immunogenum. Antimicrobial drug susceptibility testing showed that the isolate was resistant to imipenem, moxifloxacin, and doxycycline; intermediately sensitive to tobramycin and linezolid; and sensitive to amikacin, cefoxitin, and clarithromycin. The patient was treated with cefoperazone sodium and sulbactam sodium (2 g twice daily) and switched to meropenem (0.5 g every 6 hours) for anti-infection but died due to acute respiratory failure and severe pneumonia before targeted treatment for NTM-PD could be initiated.

Conclusion

NTM-PD is frequently diagnosed at an advanced stage, primarily because its clinical presentation is often atypical and definitive laboratory tests are not readily available. Therefore, greater attention should be paid to the diagnosis and treatment of NTM-PD. Nontuberculous mycobacterial infections, especially clinically rare infections, need to be diagnosed without delay and their antibiotic susceptibility needs to be determined.

Drug susceptibility profiles of Mycobacterium abscessus isolated in the state of São Paulo, 2008-2024

Introduction. Infections caused by Mycobacterium abscessus, an environmentally prevalent, rapidly growing mycobacteria, are increasingly frequent in developed countries.Objective. To analyse the drug susceptibility profiles of M. abscessus isolated in the state of São Paulo from 2008 to 2024.Methods. Of the 2,402 M. abscessus isolates identified during those 17 years, 558 (23.2%) met the American Thoracic Society's microbiologic and clinical criteria for drug susceptibility testing (DST), which was performed for five agents - clarithromycin, amikacin, cefoxitin, ciprofloxacin, and doxycycline.Results. Clarithromycin showed a dramatic increase in resistance phenotype from ≤10% in the early period to 73-90% over the last 8 years. Over half those isolates demonstrated inducible resistance. Resistance to amikacin was found in fewer than 5% of isolates from 2016 to 2021. In 2022, that result increased to 13%, but for 2023 and 2024, it had fallen back to 2%. Over the past decade, cefoxitin DST has reported the majority of isolates as intermediate, a problematic result in M. abscessus group (MAG) infections, which typically require long-term treatment for successful outcomes. Since 2018, the annual susceptibility rate has been ≤18%, and in five of the 7 years, ≤7%. Ciprofloxacin was typically assessed as susceptible from 2009 to 2011, then decreased sharply to ≤20% over the next several years, and since 2018, the rate has been less than 5%. Through the entire study, doxycycline resistance has remained consistently high; in the years since 2018, ≤6% of isolates have been susceptible.Conclusion. This study demonstrates wide variation among MAG clinical isolates in the frequency of susceptibility, both across different agents and within individual agents over time. These results emphasize the importance of performing high-quality DST on MAG clinical isolates and suggest the need to consider revising the standard panel of drugs tested.

Recent advances in immunopathogenesis and clinical practice: mastering the challenge-managing of non-tuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) are widespread environmental pathogens that can lead to significant disease burden, particularly in immunocompromised individuals, but also in those with a normal immune system. The global incidence of NTM is increasing rapidly, with Mycobacterium avium complex (MAC) being one of the most common types. The immunopathogenesis of the MAC involves a complex interaction between the bacteria and the host immune system. MAC survives and replicates within macrophages by preventing the fusion of phagosomes and lysosomes. The mycobacteria can neutralize reactive oxygen and nitrogen species produced by the macrophages through their own enzymes. Additionally, MAC modulates cytokine production, allowing it to suppress or regulate the immune response. Diagnosing MAC infections can be challenging, and the effectiveness of available treatments may be limited due to MAC's unpredictable resistance to various antimycobacterial drugs in different regions. Treating MAC infection requires a collaborative approach involving different healthcare professionals and ensuring patient compliance. This review aims to shed light on the complexities of MAC infection treatment, discussing the challenges of MAC infection diagnosis, pharmacological considerations, such as drug regimens, drug monitoring, drug interactions, and the crucial role of a multidisciplinary healthcare team in achieving the best possible treatment outcomes for patients.

In vitro activity of omadacycline against geographically diverse rapidly growing nontuberculous mycobacteria (NTM) clinical isolates

Nontuberculous mycobacteria (NTM) are emerging opportunistic pathogens with limited treatment options due to resistance to multiple antibiotic classes. This study aimed to evaluate the in vitro activity of omadacycline and comparator antibiotics against rapidly growing mycobacteria (RGM) clinical isolates. Minimum inhibitory concentration (MIC) evaluation of RGM clinical isolates was performed by two independent laboratories (EU and Japan). A total of 383 isolates (211 EU, 172 Japan) were evaluated. Omadacycline was active against all RGM species tested. For Mycobacterium abscessus subsp. abscessus, MIC50 and MIC90 values (read at 100 % inhibition) were 1 and 4 µg/mL (EU) and 0.5 and 1 µg/mL (Japan), respectively. Mycobacterium fortuitum and Mycobacterium chelonae both had MIC90 values of 0.5 µg/mL (Japan). Omadacycline has consistent, potent in vitro activity against RGM clinical isolates from 15 geographically diverse countries, and thus warrants additional studies and continued development of omadacycline as a potential treatment option for NTM-related disease.

Extrapulmonary Nontuberculous Mycobacteria Infection: The New-Age Neglected Infectious Disease

Nontuberculous mycobacteria (NTM), otherwise known as atypical mycobacteria, primarily cause pulmonary disease. However, with the increase in the immunocompromised population, infections caused by NTM at extrapulmonary (EP) sites have been on the rise in the past decade. Clinical presentations can commonly include lymphadenitis and skin and soft tissue infections. The diagnosis is challenging due to the invasive nature of the sample collection and the low degree of suspicion. Furthermore, detection up to the speciation level is important as management is species-specific. With limited data and studies regarding extrapulmonary nontuberculous mycobacteria (EP-NTM) disease, a multidisciplinary approach with awareness is required to recognize the pathogen early for appropriate and timely institution of therapy.

Severe Mycobacterium chelonae Infection Following Dermal Filler Injection: A Diagnostic and Therapeutic Challenge

This case report describes a challenging case of Mycobacterium chelonae infection in a 72-year-old immunocompetent woman following poly-L-lactic acid injection. This represents the first reported case of Mycobacterium chelonae ​​​​infection following dermal filler injections in Europe. Despite initial empiric therapy, the infection progressed, requiring multiple surgical debridements and prolonged antibiotic therapy with significant side effects. This report highlights the challenges of diagnosing and treating Mycobacterium chelonae infections, emphasizing the importance of early recognition, a multidisciplinary approach, and susceptibility-guided antibiotic therapy. The gravity of this case underscores the potential for severe complications following seemingly minor cosmetic procedures, even in immunocompetent individuals. It highlights the need for a high index of suspicion and prompt medical attention.

Pattern of rapidly growing mycobacteria (RGM) species isolated from clinical samples: A 10-year retrospective study in a tertiary care hospital of Bangladesh

PURPOSE

Infections caused by rapidly growing mycobacteria (RGM) are increasing worldwide. The study was conducted in a microbiological laboratory of Bangladesh to determine the pattern of detection of RGM from clinical samples.

METHODS

All laboratory culture records of RGM from 2012 to 2022 were collected retrospectively and analyzed.

RESULTS

A total 62 RGM infected patients with surgical site infection (74.1 %), injection site and skin abscess (9.7 %), septicaemia (4.8 %) and UTI (1.6 %) were identified. The annual isolation frequency of RGM increased 4.8 %-29.1 % in between year 2012 and 2022. RGM infected patients (14.5 %) were mistakenly treated with first line anti tubercular drug before correct microbiological diagnosis (median, IQR; 3, 2-5 months). Out of 23 RGM isolates, 86.9 % were M. abscessus and rest 13.1 % were M. fortuitum. Most of them (≥95 %) were sensitive to amikacin, linezolid, clarithromycin where as 27.1 % to imipenem and ciprofloxacin, 40 % to cefoxitin, 35.3 % and 1.7 % to doxycycline and co-trimoxazole respectively.

CONCLUSION

Misdiagnosis or delay in diagnosis and erroneous treatment with first line anti tubercular drug may cause prolong morbidity and therapeutic failure to patients with RGM infection. So, early and appropriate diagnosis is crucial for successful outcome.

Detection of Gram-Ghost Bacilli and Additional Ziehl-Neelsen Stain for the Early Diagnosis of Driveline Infection: A Case Report

BACKGROUND

Driveline infections (DLI) caused by nontuberculous mycobacteria (NTM) in patients with implantable left ventricular assist devices (iLVAD) are rare but fatal, requiring early diagnosis and appropriate treatment. Herein, we present a rare case of DLI caused by Mycobacterium chelonae, which was promptly diagnosed using Gram stain and Ziehl-Neelsen stain and followed a favorable clinical course.

CASE PRESENTATION

A 51-year-old man with an iLVAD complicated by DLI was admitted to our center. He had no fever but had a slight ache and rash around the driveline exit site on admission. The wound condition gradually deteriorated with increasing purulent discharge from the driveline exit site and an elevated inflammatory response, despite daily irrigation. Gallium scintigraphy led to the diagnosis of deep DLI, followed by surgical debridement and omental flap transposition with driveline translocation. The Gram stain of the purulent discharge from the surgical site showed unstained bacilli (Gram-neutral, neither positive nor negative) along with leukocyte phagocytosis. Additionally, the Ziehl-Neelsen stain was positive. NTM was suspected after confirming the negative polymerase chain reaction for M. tuberculosis. Antibiotic therapy was switched to a specific regimen for skin and soft tissue infections caused by NTM. After identifying M. chelonae, antibiotic therapy was switched to a more specific regimen (clarithromycin and doxycycline) for M. chelonae according to the susceptibility test results. The patient was discharged after 3 months without infection recurrence.

CONCLUSIONS

Detecting Gram-ghost bacilli and using an additional Ziehl-Neelsen stain can be beneficial for the early diagnosis of repeated DLI with unknown etiology.

Not the Silver Bullet: Uncovering the Unexpected Limited Impacts of Silver-Containing Showerheads on the Drinking Water Microbiome

The incidence of waterborne disease outbreaks in the United States attributed to drinking water-associated pathogens that can cause infections in the immunocompromised DWPIs (e.g., Legionella pneumophila, nontuberculous mycobacteria (NTM), and Pseudomonas aeruginosa, among others) appears to be increasing. An emerging technology adopted to reduce DWPIs are point-of-use devices, such as showerheads that contain silver, a known antimicrobial material. In this study, we evaluate the effect of silver-containing showerheads on DWPI density and the broader microbiome in shower water under real-use conditions in a full-scale shower system, considering three different silver-modified showerhead designs: (i) silver mesh within the showerhead, (ii) silver-coated copper mesh in the head and hose, and (iii) silver-embedded polymer composite compared to conventional plastic and metal showerheads. We found no significant difference in targeted DWPI transcriptional activity in collected water across silver and nonsilver shower head designs. Yet, the presence of silver and how it was incorporated in the showerhead influenced the metal concentrations, microbial rare taxa, and microbiome functionality. Microbial dynamics were also influenced by the showerhead age (i.e., time after installation). The results of this study provide valuable information for consumers and building managers to consider when choosing a showerhead meant to reduce microorganisms in shower water.

Rapidly growing knowledge of Mycobacterium smegmatis: A case series and review of antimicrobial susceptibility patterns

Mycobacterium smegmatis is a rapidly growing nontuberculous mycobacterium that is rarely isolated from clinical specimens and is frequently considered to be a contaminant. We conducted a retrospective review of mycobacterial cultures positive for M. smegmatis from 1998 to 2023 at our institution to evaluate the clinical significance of recovering this mycobacterium. Antimicrobial susceptibility patterns were also determined. Twenty-two M. smegmatis isolates were identified from 17 patients, 12 of whom met criteria for clinical chart review. M. smegmatis was deemed a cause of infection in 5/5 isolates from skin or soft tissue, 3/3 from bone, 1/1 from blood, and 0/3 from respiratory specimens. All cases thought to be significant were treated with at least 2 active agents for periods varying from 2 weeks up to 8 months. 18 isolates had antimicrobial susceptibility testing performed and all were susceptible to doxycycline, imipenem, linezolid, moxifloxacin, trimethoprim/sulfamethoxazole, and tobramycin while all isolates were resistant to clarithromycin. When recovered in culture, the presence of M. smegmatis should be correlated with clinical presentation as it may represent a true infection.

Demographic and clinical features of nontuberculous mycobacteria infection resulting from cosmetic procedures: a systematic review

OBJECTIVES

This systematic review aims to (1) summarize the demographic and clinical characteristics of patients with nontuberculous mycobacterial (NTM) infections following cosmetic procedures; (2) summarize the frequency of pathogenic NTM species; and (3) review and analyze the antibiotics choice as well as treatment outcomes.

METHODS

We conducted a systematic search of three electronic databases (Scopus, Embase, and PubMed) from inception to March 31, 2024. We presented demographic and clinical features and the main antibiotic strategy, along with etiological information.

RESULTS

A total of 200 patients were included in the analysis, with a median onset age of 38.0 years. The median latency period before the illness was 28 days. Nodules were the most frequently reported type of lesion, occurring in 31.0% (n = 62/200) of cases. Mycobacterium abscessus was the most commonly found NTM (45%). Clarithromycin was the most commonly applied (64.0%, n = 128/200), followed by amikacin (31.0%, n = 62/200). The median treatment duration was 6 months (0.25, 24). The overall treatment effectiveness rate was 97.4% (n = 148/152).

CONCLUSION

NTM infections caused by cosmetic procedures are rapidly increasing worldwide and present diagnostic and treatment challenges. Dermatologists and aesthetic practitioners should be aware of this relatively uncommon disease. Further research is needed to standardize management algorithms.

Mycobacterium chelonae hand infection following acupuncture: a case report and literature review

Hand infection caused by atypical mycobacteria is an uncommon condition. We present a case of hand infection caused by Mycobacterium chelonae in a patient who had undergone acupuncture. The clinical features, treatment, and outcome are described. Biopsy and cultures are essential for the diagnosis because Mycobacterium chelonae is a rare cause of human infection and is difficult to diagnose unless suspected. The patient was successfully treated through a combination of surgical excision, debridement, and antimicrobial therapy. We also reviewed the available literature to summarize the experience related to this infectious entity.

Disseminated Mycobacterium chelonae infection in kidney transplant patients

Mycobacterium chelonae (M. chelonae) is a member of the rapidly growing non-tuberous mycobacteria and can cause disseminated tissue infection, particularly, in the limbs. We reviewed medical records of two kidney transplant patients. We describe their background disease and transplantation details, with the use of immunosuppressive medication. We also discuss the presentation of M. chelonae infection and treatment. Both patients received deceased brain-dead donor kidney transplants for end-stage kidney disease. Both developed cutaneous manifestations of M. chelonae, progressing to disseminated infections. Case 1 was on low-dose prednisolone (2 mg) and tacrolimus, whereas, case 2 received varying doses of prednisolone (5-40 mg) and sirolimus. Antibiotics advised by infectious disease specialists were initiated within a month of skin lesion appearance. Effective treatment involved a combination of antibiotics such as clarithromycin, azithromycin, linezolid and tigecycline. These cases underline the efficacy of clarithromycin and azithromycin as long-term antibiotic treatment, with linezolid and tigecycline for management of acute dissemination.

EmbB and EmbC regulate the sensitivity of Mycobacterium abscessus to echinomycin

Treatment of Mycobacterium abscessus (Mab) infections is very challenging due to its intrinsic resistance to most available drugs. Therefore, it is crucial to discover novel anti-Mab drugs. In this study, we explored an intrinsic resistance mechanism through which Mab resists echinomycin (ECH). ECH showed activity against Mab at a minimum inhibitory concentration (MIC) of 2 µg/ml. A ΔembC strain in which the embC gene was knocked out showed hypersensitivity to ECH (MIC: 0.0078-0.0156 µg/ml). The MICs of ECH-resistant strains screened with reference to ΔembC ranged from 0.25 to 1 µg/ml. Mutations in EmbB, including D306A, D306N, R350G, V555I, and G581S, increased the Mab's resistance to ECH when overexpressed in ΔembC individually (MIC: 0.25-0.5 µg/ml). These EmbB mutants, edited using the CRISPR/Cpf1 system, showed heightened resistance to ECH (MIC: 0.25-0.5 µg/ml). The permeability of these Mab strains with edited genes and overexpression was reduced, as evidenced by an ethidium bromide accumulation assay, but it remained significantly higher than that of the parent Mab. In summary, our study demonstrates that ECH exerts potent anti-Mab activity and confirms that EmbB and EmbC are implicated in Mab's sensitivity to ECH. Mutation in EmbB may partially compensate for a loss of EmbC function.

Fracture-associated infection with Mycobacterium smegmatis in a 16-year old patient

We present a patient who suffered an agricultural rollover trauma and developed a fracture-associated tissue infection caused by Mycobacterium smegmatis. Since cases are rare, treatment of infections with M. smegmatis requires an interprofessional approach and the combination of surgery and adjunctive antimicrobial treatment.

Mycobacterial biofilms: Understanding the genetic factors playing significant role in pathogenesis, resistance and diagnosis

Even though the genus Mycobacterium is a diverse group consisting of a majority of environmental bacteria known as non-tuberculous mycobacteria (NTM), it also contains some of the deadliest pathogens (Mycobacterium tuberculosis) in history associated with chronic disease called tuberculosis (TB). Formation of biofilm is one of the unique strategies employed by mycobacteria to enhance their ability to survive in hostile conditions. Biofilm formation by Mycobacterium species is an emerging area of research with significant implications for understanding its pathogenesis and treatment of related infections, specifically TB. This review provides an overview of the biofilm-forming abilities of different species of Mycobacterium and the genetic factors influencing biofilm formation with a detailed focus on M. tuberculosis. Biofilm-mediated resistance is a significant challenge as it can limit antibiotic penetration and promote the survival of dormant mycobacterial cells. Key genetic factors promoting biofilm formation have been explored such as the mmpL genes involved in lipid transport and cell wall integrity as well as the groEL gene essential for mature biofilm formation. Additionally, biofilm-mediated antibiotic resistance and pathogenesis highlighting the specific niches, sites of infection along with the possible mechanisms of biofilm dissemination have been discussed. Furthermore, drug targets within mycobacterial biofilm and their role as potential biomarkers in the development of rapid diagnostic tools have been highlighted. The review summarises the current understanding of the complex nature of Mycobacterium biofilm and its clinical implications, paving the way for advancements in the field of disease diagnosis, management and treatment against its multi-drug resistant species.

Modeling nontuberculous mycobacterial infections in zebrafish

The incidence of infections due to nontuberculous mycobacteria (NTM) has increased rapidly in recent years, surpassing tuberculosis in developed countries. Due to inherent antimicrobial resistance, NTM infections are particularly difficult to treat with low cure rates. There is an urgent need to understand NTM pathogenesis and to develop novel therapeutic approaches for the treatment of NTM diseases. Zebrafish have emerged as an excellent animal model due to genetic amenability and optical transparency during embryonic development, allowing spatiotemporal visualization of host-pathogen interactions. Furthermore, adult zebrafish possess fully functional innate and adaptive immunity and recapitulate important pathophysiological hallmarks of mycobacterial infection. Here, we report recent breakthroughs in understanding the hallmarks of NTM infections using the zebrafish model.

Anti-biofilm activities and antibiotic synergy of naturally occurring compounds against drug-resistant rapidly growing mycobacteria

Some naturally occurring compounds, known for their antimicrobial activities, have been employed as food additives. However, their efficacy in treating infections caused by antibiotic-resistant bacteria is yet to be fully explored. Rapidly growing mycobacteria (RGM), a category within nontuberculous mycobacteria (NTM), are prevalent in various environments and can lead to infections in humans. The rise of antimicrobial resistance within RGM is a documented concern. In this study, we reported that four specific natural compounds effectively inhibited the growth and biofilm formation of three key RGM pathogens M. abscessus, M. fortuitum, and M. chelonae. We screened 12 natural compounds for their effectiveness against antibiotic-resistant clinical strains of RGM. Four compounds showed significant inhibitory effects from the most effective to least: trans-cinnamaldehyde, carvacrol, gentisaldehyde, and phloroglucinaldehyde. In the analysis of time-killing kinetics, gentisaldehyde and phloroglucinaldehyde displayed bactericidal activity while trans-cinnamaldehyde and carvacrol exhibited bacteriostatic effects. At 1× minimal inhibition concentrations, these compounds significantly reduced biofilm formation in all three RGM species to levels between 2.9% and 20.5% relative to controls. Checkerboard assays indicated synergistic interactions between these four compounds and antibiotics such as amikacin, clarithromycin, and linezolid. Of these 12 compound-antibiotic combinations, the pairs of carvacrol-linezolid, carvacrol-amikacin, and gentisaldehyde-clarithromycin demonstrated the most synergy against multiple RGM strains. Moreover, two other compounds citral and geraniol showed synergism with all three test antibiotics. Time-killing assays further confirmed most of synergistic combinations identified in the checkerboard tests. Our research suggests the potential of these essential oils and phenolic aldehydes, both individually and in combination with antibiotics, in treating RGM infections. In addition, this work illuminates applications of these natural compounds in environmental remediation to mitigate bacterial persistence for the control of infectious diseases.

IMPORTANCE

The emergence of antimicrobial resistance within rapidly growing mycobacteria (RGM) poses a significant threat to public health. This study investigates the potential of naturally occurring compounds to combat infections caused by antibiotic-resistant RGM including M. abscessus, M. fortuitum, and M. chelonae. We identified four specific natural compounds showing impressive inhibitory effects against antibiotic-resistant clinical strains. These compounds not only inhibited the growth and biofilm formation but also exhibited synergistic interactions with antibiotics against key RGM pathogens. Our findings highlight the alternative treatment strategies for RGM infections and potential environmental applications of these natural compounds in mitigating microbial persistence and controlling infectious diseases.

In vitro activity of gepotidacin and comparator antimicrobials against isolates of nontuberculous mycobacteria (NTM)

Novel antimicrobials are needed to treat rising nontuberculous mycobacteria (NTM) infections. Using standard broth microdilution methods, 68 NTM isolates were tested against gepotidacin, a new, first-in-class, oral triazaacenaphthylene bacterial topoisomerase inhibitor. MICs varied (0.25 to >64 µg/mL) with the lowest being M. fortuitum complex (0.25-8 µg/mL), M. mucogenicum complex (1-2 µg/mL), M. kansasii (0.25-8 µg/mL), and M. marinum (4-16 µg/mL). Testing greater numbers of some species is suggested to better understand gepotidacin activity against NTM.

Epidemiology of Mycobacterium abscessus

BACKGROUND

Nontuberculous mycobacteria (NTM) are highly abundant in soil, dust, and water sources, making human-pathogen contact frequent and recurrent. NTM represents over 200 species/subspecies; some are considered strict or opportunistic pathogens. Mycobacterium abscessus, often regarded as one of the most antibiotic-resistant mycobacteria, is the second most frequent NTM pulmonary disease pathogen.

OBJECTIVES

To describe the epidemiology of M. abscessus through a literature review focusing on clinical aspects.

SOURCES

We conducted searches on PubMed and Web of Knowledge for articles published from 2010 to the present using the keywords 'Mycobacterium abscessus', 'Nontuberculous mycobacteria', and 'epidemiology'. Our search prioritized original reports on the occurrence of NTM and M. abscessus infection/disease.

CONTENT

Advanced molecular and genetic diagnostic techniques have refined the M. abscessus complex (MABC) microbiological classification over the last few decades. MABC can adhere to surfaces and form a biofilm. This characteristic and its resistance to common disinfectants allow these microorganisms to persist in the water distribution systems, becoming a constant reservoir. The frequency and manifestation of NTM species vary geographically because of environmental conditions and population susceptibility differences. MABC lung disease, the most frequent site of NTM infection in humans, is often seen in patients with underlying lung diseases such as bronchiectasis, whereas MABC disseminated disease is related to immunosuppression. Skin and soft tissue infections are associated with surgical or injection procedures. Epidemiological evidence suggests an overall increase in MABC infection and disease in the last decade.

IMPLICATIONS

Establishing the burden of this disease is challenging because of varying measures of incidence and prevalence, referral bias, and differences in medical practices and reporting. Furthermore, environmental and structural determinants, infection routes, and MABC pulmonary disease mechanisms require additional investigation. This review contributes to a better understanding of the epidemiology of MABC, which could inform clinical practice and future research.

Management of M. abscessus subsp. abscessus early-onset prosthetic joint infection: Case report and literature review

Nontuberculous mycobacteria are a rare but still emerging cause of difficult-to-treat prosthetic joint infection. To our knowledge only 17 cases of M. abscessus complex prosthetic joint infection are reported in literature, of which only 1 is by M. abscessus subps. abscessus. No guidelines are available for this clinical scenario. We describe a 68-years-old female patient with an early-onset M. abscessus subsp. abscessus prosthetic joint infection, successfully treated with a tailored medical-surgical strategy, and present an overview of cases currently available in the literature to assist physicians in the management of these uncommon infections.

Significance of early diagnosis and surgical management in treating Mycobacterium immunogenum-related pyogenic extensor tenosynovitis: a case report

BACKGROUND

Non-tuberculous mycobacteria (NTM) are environmental organisms that are increasingly contributing to human infections. Mycobacterium immunogenum, a variant of NTM discovered in 2001, is a rapidly growing mycobacterium that exhibits multidrug resistance. Reports of infections caused by this organism, particularly tenosynovitis in the musculoskeletal system, are limited.

CASE PRESENTATION

A 71-year-old female with vesicular pemphigus, undergoing immunosuppressive therapy, presented with a progressively enlarging tumour on the dorsum of her right hand, along with erythematous papules that extended across her right forearm. The specimens of skin tissues and blood cultures revealed the presence of M. immunogenum. Magnetic resonance imaging evaluation led to the diagnosis of pyogenic extensor tenosynovitis. A multidrug regimen, comprising amikacin and clarithromycin, was initiated, followed by synovectomy. The patient underwent a course of 180 days of antimicrobial therapy and demonstrated no signs of disease recurrence one year after treatment completion.

CONCLUSION

Early diagnosis and surgical intervention are crucial to prevent the adverse prognostic implications of pyogenic extensor tenosynovitis caused by M. immunogenum. Effective management requires precise microbial identification and susceptibility testing, necessitating collaborative engagement with microbiological laboratories.

Mycobacterium porcinum Disseminated Infection in Non-severely Immunocompromised Host

Mycobacterium porcinum is a nontuberculous mycobacteria (NTM) recently identified to cause human infection. Correct speciation of NTMs can be difficult and result in misdiagnosis and delayed treatment. Because of the paucity of the literature, there is a lack of awareness of the possibility of serious infections caused by M. porcinum. Although severe infections tend to occur in individuals with certain risk factors, the primary being an immunocompromised state, our case illustrates that it can also be possible in non-severely immunocompromised individuals. A 65-year-old male with a medical history of diabetes mellitus (DM), end-stage renal disease (ESRD) on hemodialysis (HD), congestive heart failure (CHF), and chronic obstructive pulmonary disease (COPD) was admitted to the emergency room due to a laceration on his right lower leg following a fall. He reported shortness of breath but denied other respiratory symptoms. On examination, he showed signs of infection and increased oxygen requirement compared to baseline. Blood culture was positive for acid-fast bacilli (AFB), initially reported as M. avium complex (MAC) and later confirmed as M. porcinum through gene sequencing and morphology analysis. Interval blood cultures taken a week later confirmed true M. porcinum bacteremia. Treatment initially involved intravenous antibiotics- imipenem and ciprofloxacin before transitioning to oral linezolid and ciprofloxacin based on sensitivities. Following 10 days of antibiotic therapy, subsequent blood cultures returned negative, and treatment with oral antibiotics was advised, with continued outpatient follow-up with infectious disease in two weeks. M. porcinum, typically considered a contaminant in healthy individuals, was identified as the causative agent of a disseminated infection in a non-severely immunocompromised patient. This case underscores the importance of accurately identifying the specific mycobacterial species, confirming true infection, and conducting antibiotic susceptibility testing due to the distinct antibiotic susceptibility profile of M. porcinum compared to other NTM like MAC.

Diagnosis and Management of Infections in Patients with Mendelian Susceptibility to Mycobacterial Disease

The diagnosis and treatment of patients with mendelian susceptibility to mycobacterial disease (MSMD) pose consistent challenges due to the diverse infection spectrum observed in this population. Common clinical manifestations include Bacillus Calmette-Guérin vaccine (BCG) complications in countries where routine BCG vaccination is practiced, while in non-BCG-vaccinating countries, Non-Tuberculous Mycobacteria (NTM) is prevalent. In tuberculosis-endemic regions, Mycobacterium tuberculosis (MTB) has a high prevalence, along with other intracellular organisms. Isolating these organisms presents a significant challenge, and treatment is often initiated without confirming the specific species. This review primarily focuses on the methods and challenges associated with diagnosing and treating MSMD patients.

Mycobacterium abscessus endocarditis post cardiac cathetrisation-a case report and review of 25 cases (2001-2023)

47 year male underwent percutaneous transluminal coronary angioplasty elsewhere, developed fever after two days, and treated empirically in various hospitals for the subsequent two months. Echocardiography showed vegetation in aortic valve and blood cultures were negative. He was then diagnosed as a case of endocarditis due to M. abscessus in our centre by repeated positive blood cultures. After treatment with Imipenem, Amikacin and clarithromycin in the background of pancytopenia, patient was discharged with advice to continue antibiotics and planned for aortic valve replacement. Patient was noncompliant to treatment, readmitted with worsening symptoms, developed multiorgan failure and subsequently died of infection.

The interplay between the polar growth determinant DivIVA, the segregation protein ParA, and their novel interaction partner PapM controls the Mycobacterium smegmatis cell cycle by modulation of DivIVA subcellular distribution

IMPORTANCE

The genus of Mycobacterium includes important clinical pathogens (M. tuberculosis). Bacteria of this genus share the unusual features of their cell cycle such as asymmetric polar cell elongation and long generation time. Markedly, control of the mycobacterial cell cycle still remains not fully understood. The main cell growth determinant in mycobacteria is the essential protein DivIVA, which is also involved in cell division. DivIVA activity is controlled by phosphorylation, but the mechanism and significance of this process are unknown. Here, we show how the previously established protein interaction partner of DivIVA in mycobacteria, the segregation protein ParA, affects the DivIVA subcellular distribution. We also demonstrate the role of a newly identified M. smegmatis DivIVA and ParA interaction partner, a protein named PapM, and we establish how their interactions are modulated by phosphorylation. Demonstrating that the tripartite interplay affects the mycobacterial cell cycle contributes to the general understanding of mycobacterial growth regulation.

A bronchoscopy-associated pseudo-outbreak of Mycobacterium chelonae and Mycobacterium mucogenicum associated with contaminated ice machine water and ice

A pseudo-outbreak of bronchoscopy-associated Mycobacterium chelonae and M. mucogenicum was traced to contaminated ice machine water and ice. A nonsterile ice bath was used to cool uncapped, sterile, saline syringes used to slow procedural bleeding. Joining the growing evidence of bronchoscopy pseudo-outbreaks, our investigation describes several lessons for future prevention.

A case report on Mycobacterium houstonense infection after total hip arthroplasty

BACKGROUND

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

CASE PRESENTATION

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

CONCLUSION

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

Antimicrobial Resistance in Rapidly Growing Nontuberculous Mycobacteria among Domestic and Wild Animals Emphasizing the Zoonotic Potential

Non-tuberculous mycobacteria (NTM) are opportunistic pathogens capable of causing infections in humans and animals. The aim of this study was to demonstrate the potential role of domestic and wild animals as a reservoir of multiple resistant, rapidly growing NTM strains representing a potential zoonotic threat to humans. A total of 87 animal isolates belonging to 11 rapidly growing species (visible colonies appear within three to seven days) were genotyped and tested for susceptibility to the 15 most commonly used antibiotics in the treatment of such infections in a human clinic. By determining the antimicrobial susceptibility, the most prevalent resistance was found to cephalosporins (>50%), followed by amoxicillin-clavulanate (31.0%), clarithromycin (23.0%), tobramycin (14.9%) and doxycycline (10.3%). Resistance to imipenem, ciprofloxacin, minocycline and linezolid was notably lower (<7.0%). All tested isolates were susceptible to amikacin and moxifloxacin. The most frequent resistance was proved in the most pathogenic species: M. fortuitum, M. neoaurum, M. vaccae and M. porcinum. Meanwhile, other species displayed a higher sensitivity rate. No significant resistance differences between domestic and wild animals were found. The established significant frequency of resistance highlights the significant zoonotic potential posed by circulating rapidly growing NTM strains, which could lead to challenges in the treatment of these infections.

Application of FT-IR Spectroscopy for Mycobacterium abscessus complex subspecies differentiation

Mycobacterium abscessus complex (MABSC) subspecies differentiation improves patients' therapy and outcome. Fourier-Transform-Infrared Spectroscopy (FT-IRS) was applied for subspecies discrimination of 15 strains on different media: Löwenstein-Jensen showed the best resolution power; Linear Discriminant Analysis model differentiated M. abscessus susbsp. abscessus from M. abscessus subsp. massiliense. FT-IRS has a potential role in rapidly MABSC subspecies identification.

Osteomyelitis in the Left First Toe Due to Mycobacterium abscessus after an Injury

"Non-tuberculous mycobacteria" (NTM) is a general term for pathogenic mycobacteria other than Mycobacterium tuberculosis and Mycobacterium leprae. Non-tuberculous mycobacteria are widely present in the natural environment, including soil and water, with over 150 reported species. Mycobacterium abscessus is rare among Non-tuberculous mycobacteria, and there are few reports of extrapulmonary lesions due to Mycobacterium abscessus. We describe a case of osteomyelitis in an adult woman's left first toe caused by Mycobacterium abscessus. The osteomyelitis developed due to an injury in a public bathing facility. A combination of surgical debridement and multidrug therapy was effective. When antimicrobial agents are ineffective in trauma linked to water or soil, mycobacterial infections, including Non-tuberculous mycobacteria, should be considered as differential diagnoses, and laboratory culture targeted to mycobacteria would be recommended.

In Vitro and In Vivo Efficacy of NITD-916 against Mycobacterium fortuitum

Mycobacterium fortuitum represents one of the most clinically relevant rapid-growing mycobacterial species. Treatments are complex due to antibiotic resistance and to severe side effects of effective drugs, prolonged time of treatment, and co-infection with other pathogens. Herein, we explored the activity of NITD-916, a direct inhibitor of the enoyl-ACP reductase InhA of the type II fatty acid synthase in Mycobacterium tuberculosis. We found that this compound displayed very low MIC values against a panel of M. fortuitum clinical strains and exerted potent antimicrobial activity against M. fortuitum in macrophages. Remarkably, the compound was also highly efficacious in a zebrafish model of infection. Short duration treatments were sufficient to significantly protect the infected larvae from M. fortuitum-induced killing, which correlated with reduced bacterial burdens and abscesses. Biochemical analyses demonstrated an inhibition of de novo synthesis of mycolic acids. Resolving the crystal structure of the InhAMFO in complex with NAD and NITD-916 confirmed that NITD-916 is a direct inhibitor of InhAMFO. Importantly, single nucleotide polymorphism leading to a G96S substitution in InhAMFO conferred high resistance levels to NITD-916, thus resolving its target in M. fortuitum. Overall, these findings indicate that NITD-916 is highly active against M. fortuitum both in vitro and in vivo and should be considered in future preclinical evaluations for the treatment of M. fortuitum pulmonary diseases.

Skin and soft tissue infections due to rapidly growing mycobacteria

PURPOSE OF REVIEW

The aim of this article is to review skin and soft tissue infections due to rapidly growing mycobacteria (RGM), with a particular focus on recently published literature (2021-2022).

RECENT FINDINGS

RGM are increasingly reported as a cause of skin and soft tissue infections, both in the community setting and as a cause of nosocomial outbreaks. Recent advances in molecular methods have expanded the number of species of RGM and resulted in increased diagnosis. New treatment options are under evaluation particularly for Mycobacterium abscessus , the most difficult-to-treat among RGM.

SUMMARY

RGM are an uncommon cause of skin and soft tissue infections and a high clinical suspicion together with advanced laboratory facilities are required for diagnosis. Species identification and antimicrobial susceptibility testing are essential to drive appropriate treatment, which combines surgical debridement with prolonged antimycobacterial combination therapy.

A Systematic Review of Nontuberculous Mycobacterium Infection Following Anterior Cruciate Ligament Reconstruction

Although infection following anterior cruciate ligament (ACL) reconstruction is rare, these cases have potentially catastrophic ramifications. Nontuberculous mycobacteria (NTM) are ubiquitous, located in the water supply and soil. Our objective was to review the literature to characterize NTM infection following ACL reconstruction.

Methods

A database search was performed for arthroscopic ACL reconstructions that resulted in a postoperative diagnosis of NTM infection.

Results

The literature search returned 6 case reports that met the inclusion criteria. The initial postoperative presentation occurred after 3 to 52 weeks, which is consistent with reports of postoperative NTM infection.

Conclusions

The common indolent course of NTM infection hinders prompt diagnosis and treatment. Organism susceptibility testing is crucial for effective treatment and limiting unnecessary antibiotic exposure.

Clinical Relevance

The duration of medical treatment for NTM infection is 4 to 6 months, depending on the severity of disease and species. Based on the aggregate literature, we recommend removal of local implants if the infection is localized and without articular involvement. However, in cases of articular involvement, all fixation and graft material should be removed.

A case of novel, rapidly-growing Mycolicibacter kumamotonensis infection in a patient with severe pulmonary disease treated in New York City

INTRODUCTION

Mycolicibacter kumamotonensis is a slowly growing, non-chromogenic non-tuberculous mycobacteria (NTM) that was initially distinguished from the M. terrae complex in 2006. Since then it has been rarely reported as the cause of pulmonary and soft-tissue infections in both immunocompromised and immunocompetent patients.

CASE PRESENTATION

We present a case of severe pulmonary disease due to Mycolicibacter kumamotonensis in a 57-year-old male who was immunocompetent at time of diagnosis, with a history of interstitial lung disease and a prior diagnosis of tuberculosis (TB). After initial treatment for TB in 2017, his condition stabilized until a recurrence in September 2021, leading to an evaluation for lung transplant in the setting of pulmonary fibrosis and emphysema which led to the identification of Mycolicibacter kumamotonensis. A lung transplant was completed, and the patient was successfully treated with a combination of Ethambutol, Azithromycin, and Rifabutin.

CONCLUSIONS

This represents the first case reported of M. kumamotonensis in a patient undergoing lung transplant, and the first case with rapid culture growth during identification of the organism (4 days). This report highlights the need for consideration of M. kumamotonensis as a pathogen in humans, with the potential for rapid growth in liquid media, and the importance of early identification to inform empiric therapy.

Skin and soft tissue infection of Nontuberculous mycobacterium after injection lipolysis

BACKGROUND

Injection lipolysis is used for body and face contouring due to its minimal invasiveness and cost-effectiveness, but related complications such as nontuberculous mycobacterium infection significantly affect its clinical application.

AIMS

This study aimed to review the literature on NTM infection after injection lipolysis.

METHODS

We conducted a literature review of scientific journals published in Medline and PubMed up to September 2022 on patients with NTM skin and soft tissue infections. We used the keywords: nontuberculous mycobacterium, infection, injection lipolysis, and lipolytic solution in various combinations with the Boolean operators AND, OR, and NOT. Only articles available in English and full version publications were considered for this review. Here, we reviewed the relevant mechanisms and drugs for injectable lipolysis and analyzed the possible correlation between NTM infection and injection lipolysis. We also summarize methods for the diagnosis and treatment of NTM infections and present some perspectives on this therapy.

RESULTS

Many patients with NTM infections had a history of fat-related surgery or therapy. NTM infection after injection lipolysis may be related to inadequate disinfection and sterilization of injection equipment and clinical procedures, the unqualified medication itself and free fatty acids released during injection lipolysis. Currently, diagnosis and treatment of NTM infection after lipolysis injections remains challenging.

CONCLUSIONS

Injection lipolysis represents a helpful option for local fat reduction. Doctors should strictly abide by the aseptic operation standards and use qualified products for there is a correlation between skin and soft tissue infection of nontuberculous mycobacterium and injection lipolysis. Providers should understand the mechanism, indications, and associated risks of injection lipolysis when injecting fat-dissolving drugs to reduce localized fat.

Comparative genome analysis reveals high-level drug resistance markers in a clinical isolate of Mycobacterium fortuitum subsp. fortuitum MF GZ001

Introduction

Infections caused by non-tuberculosis mycobacteria are significantly worsening across the globe. M. fortuitum complex is a rapidly growing pathogenic species that is of clinical relevance to both humans and animals. This pathogen has the potential to create adverse effects on human healthcare.

Methods

The MF GZ001 clinical strain was collected from the sputum of a 45-year-old male patient with a pulmonary infection. The morphological studies, comparative genomic analysis, and drug resistance profiles along with variants detection were performed in this study. In addition, comparative analysis of virulence genes led us to understand the pathogenicity of this organism.

Results

Bacterial growth kinetics and morphology confirmed that MF GZ001 is a rapidly growing species with a rough morphotype. The MF GZ001 contains 6413573 bp genome size with 66.18 % high G+C content. MF GZ001 possesses a larger genome than other related mycobacteria and included 6156 protein-coding genes. Molecular phylogenetic tree, collinearity, and comparative genomic analysis suggested that MF GZ001 is a novel member of the M. fortuitum complex. We carried out the drug resistance profile analysis and found single nucleotide polymorphism (SNP) mutations in key drug resistance genes such as rpoB, katG, AAC(2')-Ib, gyrA, gyrB, embB, pncA, blaF, thyA, embC, embR, and iniA. In addition, the MF GZ001strain contains mutations in iniA, iniC, pncA, and ribD which conferred resistance to isoniazid, ethambutol, pyrazinamide, and para-aminosalicylic acid respectively, which are not frequently observed in rapidly growing mycobacteria. A wide variety of predicted putative potential virulence genes were found in MF GZ001, most of which are shared with well-recognized mycobacterial species with high pathogenic profiles such as M. tuberculosis and M. abscessus.

Discussion

Our identified novel features of a pathogenic member of the M. fortuitum complex will provide the foundation for further investigation of mycobacterial pathogenicity and effective treatment.

Shower water contributes viable nontuberculous mycobacteria to indoor air

Nontuberculous mycobacteria (NTM) are frequently present in municipal drinking water and building plumbing, and some are believed to cause respiratory tract infections through inhalation of NTM-containing aerosols generated during showering. However, the present understanding of NTM transfer from water to air is insufficient to develop NTM risk mitigation strategies. This study aimed to characterize the contribution of shower water to the abundance of viable NTM in indoor air. Shower water and indoor air samples were collected, and 16S rRNA and rpoB genes were sequenced. The sequencing results showed that running the shower impacted the bacterial community structure and NTM species composition in indoor air by transferring certain bacteria from water to air. A mass balance model combined with NTM quantification results revealed that on average 1/132 and 1/254 of NTM cells in water were transferred to air during 1 hour of showering using a rain and massage showerhead, respectively. A large fraction of the bacteria transferred from water to air were membrane-damaged, i.e. they had compromised membranes based on analysis by live/dead staining and flow cytometry. However, the damaged NTM in air were recoverable as shown by growth in a culture medium mimicking the respiratory secretions of people with cystic fibrosis, implying a potential infection risk by NTM introduced to indoor air during shower running. Among the recovered NTM, Mycobacterium mucogenicum was the dominant species as determined by rpoB gene sequencing. Overall, this study lays the groundwork for future pathogen risk management and public health protection in the built environment.

Host DNA depletion can increase the sensitivity of Mycobacterium spp. detection through shotgun metagenomics in sputum

Identification and phenotypic drug-susceptibility testing for mycobacteria are time-consuming and challenging but essential for managing mycobacterial infections. Next-generation sequencing (NGS) technologies can increase diagnostic speed and quality, but standardization is still lacking for many aspects (e.g., unbiased extraction, host depletion, bioinformatic analysis). Targeted PCR approaches directly on sample material are limited by the number of targets that can be included. Unbiased shotgun metagenomics on direct material is hampered by the massive amount of host DNA, which should be removed to improve the microbial detection sensitivity. For this reason, we developed a method for NGS-based diagnosis of mycobacteria directly from patient material. As a model, we used the non-tuberculous mycobacterium (NTM) Mycobacterium abscessus. We first compared the efficiency of three different DNA extraction kits for isolating DNA (quality and concentration). The two most efficient kits were then used in a follow-up study using artificial sputum. Finally, one extraction kit was selected and further evaluated for DNA isolation from a patients’ sputum mixture spiked with M. abscessus at three concentrations (final concentrations 108, 107, 106  CFU/ml). The spiked sputum samples were processed with and without saponin treatment (ST) in combination with DNAse treatment prior to bacterial DNA extraction to evaluate the recovery of bacteria and depletion of host DNA by PCR and Illumina sequencing.

While Ct values of the qPCR targeting mycobacterial ITS DNA remained rather stable, Ct values in the qPCR targeting the human β-actin gene increased by five Ct values in ST samples. In subsequent Illumina sequencing, a decrease of 89% of reads mapped to the human genome was observed in ST samples. The percentage of reads mapped to M. abscessus (108 CFU/ml) increased by 89%, and the sequencing depth increased two times when undergoing ST.

In conclusion, the sensitivity of M. abscessus detection in artificial sputum was increased using a saponin pre-treatment step. The saponin followed by the DNase I treatment approach could be efficiently applied to detect and characterize mycobacterial infections, including tuberculosis, directly from sputum.

Nontuberculous Mycobacterial Infections Associated With Left Ventricular Assist Devices in 3 Patients

Durable left ventricular assist devices (LVADs) provide circulatory support in patients with end-stage heart failure; however, complications include infection of the driveline exit site. Nontuberculous mycobacterial infections are rare in patients with LVADs, but they should be considered in those who have undergone device exchanges and have bacterial infections with driveline exit-site discharge but no fever or leukocytosis. We reviewed the charts of patients who had an LVAD implanted at our institution from January 2009 through December 2019, to identify those with a device-related nontuberculous mycobacterial infection. Collected data included patient demographics, premorbid conditions, infection type, previous device complications, treatment, and outcomes. We identified infections in 3 patients (mean age, 41 yr): Mycobacterium abscessus in 2 and M. chimaera in 1. All had a HeartMate II device and had undergone device exchanges for pump thrombosis or for driveline fault or infections. All presented with driveline exit-site discharge without fever or leukocytosis. The mean time between initial device implantation and diagnosis of a nontuberculous mycobacterial infection was 55 months. All 3 patients were treated with antibiotics and underwent localized surgical débridement; one underwent an additional device exchange. The M. abscessus infections disseminated, and both patients died; the patient with M. chimaera infection continued to take suppressive antibiotics. Nontuberculous mycobacterial infections are associated with high morbidity and mortality rates, warranting prompt diagnosis and treatment.

Central nervous system infection caused by Mycobacterium houstonense: A case report

Background

Mycobacterium houstonense is a rapidly growing mycobacterium (RGM) that belongs to the unnamed third biovariant complex of the Mycobacterium fortuitum group, which is rarely responsible for human infection. Approximately 76% of infections caused by the M. fortuitum group occur after open fractures or skin, soft tissue, bone, or puncture wounds. To date, only a few cases of human infectious disease caused by M. houstonense have been reported worldwide.

Case presentation

We present a case of a 26-year-old man with a central nervous system (CNS) infection caused by M. houstonense. The patient was transferred to our hospital because of headaches and muscle strength changes. One month prior to presentation at our hospital, the patient was diagnosed with tuberculous meningitis at the other two hospitals, but his condition did not improve after anti-tuberculous treatment, antibiotics, and anti-viral treatment before admission to our hospital. Lumbar puncture was performed at both previous hospitals, as well as at our hospital; the results consistently indicated high cerebrospinal fluid (CSF) opening pressure. M. houstonense was detected in the CSF of the second hospital's lumbar puncture by metagenomic next-generation sequencing (mNGS) but was not identified at our hospital. The patient was discharged from our hospital after receiving non-tuberculous mycobacterium (NTM) treatment for 1 month according to the Chinese NTM guidelines. However, the patient died 20 days after discharge.

Conclusion

Since it is difficult to identify M. houstonense, this is the first case of human CNS infection caused by M. houstonense in China. This case may be considered by neurologists and infectious physicians when CNS infection does not respond to conventional treatment, especially in the uncommon type of NTM.

New RAPMYCOI SensititreTM Antimicrobial Susceptibility Test for Atypical Rapidly Growing Mycobacteria (RGM)

Rapidly growing mycobacteria (RGM) cause an increasing international concern, mainly due to their natural resistance to many antibiotics. The aim of this study was to conduct species identification and determine the antimicrobial susceptibility profiles of RGM isolated in Poland. Antimicrobial susceptibility was tested using broth microdilution and the RAPMYCOI panel. A total of 60 strains were analysed, including the following species: M. fortuitum complex (30), M. abscessus subsp. abscessus (16), M. abscessus subsp. massiliense (7), M. chelonae (5), and M. mucogenicum (2). For 12 M. abscessus subsp. abscessus strains, the presence of the erm 41T28 genotype associated with inducible macrolide resistance and a functional erm gene was confirmed. A MUT2 mutation in the rrl gene (constitutive resistance) was identified for two strains from the subtype M. abscessus subsp. massiliense. Among the 15 tested antibiotics, amikacin and linezolid had the strongest antimycobacterial activity. Most of the tested strains were resistant to doxycycline and trimethoprim/sulfamethoxazole. Tigecycline MICs were low for all tested strains. Findings from our study highlight the importance of correct identification of clinical isolates and antimicrobial susceptibility testing.

First case of systemic fatal mycobacteriosis caused by Mycobacterium goodii in a pet Kenyan sand boa (Eryx colubrinus loveridgei)

BACKGROUND

Environmental nontuberculous mycobacteria species that are not members of the M. tuberculosis complex, are ordinary inhabitants of a wide variety of environmental reservoirs and their role in human and animal diseases has been fully recognized. Even if spontaneous mycobacterial infections have been reported in a wide variety of reptiles, this is the first report of systemic fatal mycobacteriosis sustained by Mycobacterium goodii in a pet reptile.  CASE PRESENTATION: An adult, wild caught (WC), male Kenyan sand boa (Eryx colubrinus loveridgei) age unknown, was presented for clinical examination due to decreased activity level, decreased appetite and diarrhea. Blood tests showed unreliable results. Coprologic exam showed a moderate to severe presence of flagellates. X rays and ultrasound showed moderate presence of air and faeces in the large intestine. The snake was hospitalized and oral metronidazole was chosen as antiprotozoal agent in association with subcutaneous warm fluids. The snake was discharged after 2 weeks therapy in good clinical condition. Faecal exam resulted negative. One month after, the snake was quickly hospitalized again because of a recrudescence of symptoms. Biochemistry showed severe increase of AST, ALT and biliary acids. Severe leucocytosis and moderate to severe anemia were highlighted. Ultrasound examination revealed a severe diffused alteration of the liver parenchyma and a fine needle aspiration was performed. The cytological diagnosis was mixed inflammation, with a numerous of unstained rod-shaped bacteria both inside macrophages and free in the sample. The snake's condition rapidly deteriorated and euthanasia was performed. The histology of the coelomic organs confirmed a systemic mycobacteriosis. Real-time PCR identified the mycobacteria as Mycobacterium goodii.

CONCLUSIONS

Species from the genus Mycobacterium are among the most important micro-organism including the causative agents of tuberculosis. Even if the general incidence of disease in reptiles due to mycobacteria is comparatively low, they can serve as reservoirs of many ubiquitous mycobacteria species. Mycobacterium goodii is a rapidly growing non-tuberculous mycobacterium that has recently been associated with severe infections in animals and humans. Although in this case the pathogenesis was not completely clear, we highlight the zoonotic risk of mycobacteriosis in exotic animals especially in WC specimens.

Rapid Detection of Clarithromycin and Amikacin Resistance in Mycobacterium abscessus Complex by High-Resolution Melting Curve Analysis

The emergence of Mycobacterium abscessus complex (MABC) infection is the most noteworthy health care problem. Clarithromycin (CLA) and amikacin (AMK) constitute the cornerstone of treatment for patients infected with MABC; thus, early detection of resistance to these two drugs is essential for formulating effective therapeutic regimens. In the present study, we aimed to validate the use of MeltPro MAB assay, a melting curve analysis with dually labeled probes, on a set of clinical isolates to detect CLA and AMK resistance. A total of 103 clinical MABC strains were collected in our analysis, including 76 strains of M. abscessussubsp. Abscessus (MAA) and 27 strains of M. abscessussubsp. Massiliense (MAM). In vitro susceptibility testing revealed that two isolates exhibited intrinsic CLA resistance by harboring A2270T mutation in rrl, and inducible resistance was noted in 42 isolates. Additionally, two MAA isolates with erm(41)T28 genotype were susceptible to CLA. Notably, we found three out of 44 isolates had two melting curve peaks, representing the simultaneous presence of mutant and the wild type in these specimens. In contrast, no known mutations were identified in six AMK-resistant isolates. Further analysis revealed that MeltPro yielded 100% and 96.67% sensitivity and specificity for detecting CLA resistance. In summary, this study firstly demonstrates that MeltPro is a promising diagnostic for early detection of CLA resistance for MABC isolates, which significantly improves the turnaround time within 2 h. Approximate two fifths of MABC isolates are resistant to CLA by 23S rRNA mutation or its methylation, emphasizing the urgent need for early detection of CLA resistance prior to empirical treatment of MABC infections.

IMPORTANCEMycobacterium abscessus complex (MABC) has attracted increasing attention due to the numerous cases of infection. This pathogen is notorious for its intrinsic drug resistance, which complicates clinical management of patients with MABC infections. Clarithromycin (CLA) and amikacin (AMK) are the cornerstone of treatment regimens for MABC. Herein, our data firstly demonstrates that MeltPro is a promising diagnostic for early detection of CLA resistance for MABC isolates. The high frequency of CLA-resistant MABC isolates in China emphasizes the urgent need for early detection of CLA resistance prior to empirical treatment of MABC infections.

Mycobacterium fortuitum pacemaker infection: A case report

BACKGROUND

Mycobacterium fortuitum is a rapidly growing mycobacterium, ubiquitous in soil and water, but it is an uncommon cause of infections in immunocompetent hosts. Cardiac device infections and bloodstream infections due to non-tuberculous mycobacteria are rare.

CASE PRESENTATION

We present the case of an 85-year-old patient with infective endocarditis and pacemaker lead infection secondary to M. fortuitum.

Cardiovascular device infections due to rapidly growing Mycobacteria: A review of cases at a tertiary care hospital

Cardiovascular device infection due to rapidly growing mycobacteria (RGM) is rarely encountered in clinical practice. Due to the increasing number of indications and use of cardiovascular devices in an aging population, optimized management of these infections is of great importance. We report seven cases of RGM cardiovascular device infection. Three patients had left-ventricular assist device (LVAD) infections; two patients had cardiovascular implantable device (CIED) infections; and one had an aortic vascular stent infection. Specific cardiac valvular infection was not detected among any of the patients. All patients had a high number of comorbidities which limited some patients from receiving optimal combination antimicrobial therapy. The prognosis of cardiovascular device infections with RGM is guarded with only four patients still alive; however, the treatment approach for each patient varied considerably and often based on concurrent medical conditions, overall adjustments to goals of care, and specific patient preferences. Further analysis of cardiovascular device infections with RGM is warranted to establish a more systematic approach in successful management.

Mycobacterium abscessus and Mycobacterium massiliense exhibit distinct host and organ specificity: a cross-sectional study

PURPOSE

Precise subspeciation of Mycobacterium abscessus complex (MAB) is crucial for predicting antibiotic susceptibilities and patient outcomes. However, routine clinical microbiology laboratories have limited diagnostic tools for the differentiation of the subspecies. Thus, we investigated the predictors for MAB subspecies to actuate rapid differentiation and the optimal treatment plans.

METHODS

We retrospectively identified stored clinical isolates of MAB and reviewed patient medical records to compare clinical characteristics, sites of infection, and outcomes among patients infected with M. abscessus subsp. abscessus (M. abscessus) and M. abscessus subsp. massiliense (M. massiliense). MAB subspecies were characterized by multilocus sequence analysis with three-locus sequence (hsp65, rpoB, and secA1) and pulsed-field gel electrophoresis.

RESULTS

After outbreak and duplicated cases were excluded, 56 and 36 patients with infection caused by M. abscessus and M. massiliense, respectively, were included in the analysis. Patients with either cardiovascular disease or risk factors for cardiovascular disease (male gender and age ≥55 years) were 4.5 times more likely to harbor M. abscessus (P = 0.002), while M. massiliense was 4.8 times more frequently recovered from cutaneous and surgical wounds (P = 0.04).

CONCLUSION

Distinct host and organ specificity were observed among patients infected with M. abscessus and those with M. massiliense. These differences may provide clinically significant clues to optimize treatment strategies.