Treatment of Extrapulmonary Nontuberculous Mycobacterial Diseases

Drugs for treating infections caused by non-tubercular mycobacteria: a narrative review from the study group on mycobacteria of the Italian Society of Infectious Diseases and Tropical Medicine

BACKGROUND

Non-tuberculous mycobacteria (NTM) are generally free-living organism, widely distributed in the environment, with sporadic potential to infect. In recent years, there has been a significant increase in the global incidence of NTM-related disease, spanning across all continents and an increased mortality after the diagnosis has been reported. The decisions on whether to treat or not and which drugs to use are complex and require a multidisciplinary approach as well as patients' involvement in the decision process.

METHODS AND RESULTS

This review aims at describing the drugs used for treating NTM-associated diseases emphasizing the efficacy, tolerability, optimization strategies as well as possible drugs that might be used in case of intolerance or resistance. We also reviewed data on newer compounds highlighting the lack of randomised clinical trials for many drugs but also encouraging preliminary data for others. We also focused on non-pharmacological interventions that need to be adopted during care of individuals with NTM-associated diseases CONCLUSIONS: Despite insufficient efficacy and poor tolerability this review emphasizes the improvement in patients' care and the needs for future studies in the field of anti-NTM treatments.

Broad-Spectrum In Vitro Activity of Nα-Aroyl-N-Aryl-Phenylalanine Amides against Non-Tuberculous Mycobacteria and Comparative Analysis of RNA Polymerases

This study investigates the in vitro activity of Nα-aroyl-N-aryl-phenylalanine amides (AAPs), previously identified as antimycobacterial RNA polymerase (RNAP) inhibitors, against a panel of 25 non-tuberculous mycobacteria (NTM). The compounds, including the hit compound MMV688845, were selected based on their structural diversity and previously described activity against mycobacteria. Bacterial strains, including the M. abscessus complex, M. avium complex, and other clinically relevant NTM, were cultured and subjected to growth inhibition assays. The results demonstrate significant activity against the most common NTM pathogens from the M. abscessus and M. avium complexes. Variations in activity were observed against other NTM species, with for instance M. ulcerans displaying high susceptibility and M. xenopi and M. simiae resistance to AAPs. Comparative analysis of RNAP β and β' subunits across mycobacterial species revealed strain-specific polymorphisms, providing insights into differential compound susceptibility. While conservation of target structures was observed, differences in compound activity suggested influences beyond drug-target interactions. This study highlights the potential of AAPs as effective antimycobacterial agents and emphasizes the complex interplay between compound structure, bacterial genetics, and in vitro activity.

Pharmacotherapeutic Considerations in the Treatment of Nontuberculous Mycobacterial Infections: A Primer for Clinicians

Nontuberculous mycobacteria (NTM) can cause a variety of infections, including serious pulmonary disease. Treatment encompasses polypharmacy, with a targeted regimen of 2-5 active medications, depending on site of infection, species, and clinical characteristics. Medications may include oral, intravenous, and inhalational routes. Medication acquisition can be challenging for numerous reasons, including investigational status, limited distribution models, and insurance prior authorization. Additionally, monitoring and managing adverse reactions and drug interactions is a unique skill set. While NTM is primarily medically managed, clinicians may not be familiar with the intricacies of medication selection, procurement, and monitoring. This review offers insights into the pharmacotherapeutic considerations of this highly complex disease state, including regimen design, medication acquisition, safety monitoring, relevant drug-drug interactions, and adverse drug reactions.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Successful management of surgical site infection caused by Mycobacterium mageritense in a breast cancer patient

Mycobacterium mageritense (M. mageritense), a nontuberculous mycobacterium, is classified as a rapidly growing mycobacterium, class IV in the Runyon Classification. This bacterium is found in soil, water, and other habitats. Infections caused by M. mageritense are relatively rare and no treatment protocol has been established. Herein, we report a case of skin and soft tissue infection caused by M. mageritense. A 49-year-old woman underwent surgery for right breast cancer. Four months after surgery, a surgical site infection was found, and M. mageritense was identified in the wound culture using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Based on the sensitivity results, the patient was treated with levofloxacin and doxycycline for 4 months. In addition to antimicrobial agents, aggressive surgical interventions led to a favorable course of treatment. In conclusion, successful treatment of skin and soft tissue infections with M. mageritense requires surgical intervention whenever possible, aggressive susceptibility testing, and appropriate antimicrobial therapy.

Intracellular and in vivo activities of oxazolidinone drugs against Mycobacterium avium complex infection

The prevalence of Mycobacterium avium complex-pulmonary disease (MAC-PD) has become a growing concern worldwide, and current treatments involving macrolides (clarithromycin [CLR] or azithromycin), ethambutol, and rifampicin have limited success, highlighting the need for better therapeutic strategies. Recently, oxazolidinone drugs have been identified as novel anti-tuberculosis drugs effective against drug-resistant M. tuberculosis. However, the effects of these drugs against MAC are still controversial due to limited data. Here, we first evaluated the intracellular anti-MAC activities of two oxazolidinone drugs, linezolid (LZD) and delpazolid (DZD), against 10 macrolide-susceptible MAC strains and one macrolide-resistant M. avium strain in murine bone marrow-derived macrophages (BMDMs) and found that both drugs demonstrated similar potential. The synergistic efficacies with CLR were then determined in a chronic progressive MAC-PD murine model by initiating a 4-week treatment at 8 weeks post-infection. Upon assessment of bacterial burdens and inflamed lesions, oxazolidinone drugs exhibited no anti-MAC effect, and there was no significant difference in the synergistic effect of CLR between LZD and DZD. These findings suggest that oxazolidinone drugs inhibit intracellular bacterial growth, even against macrolide-resistant MAC, but their clinical application requires further consideration.

Unveiling the Clinical Diversity in Nontuberculous Mycobacteria (NTM) Infections: A Comprehensive Review

Once considered rare, nontuberculous mycobacterial (NTM) infections have garnered increasing attention in recent years. This comprehensive review provides insights into the epidemiology, clinical diversity, diagnostic methods, treatment strategies, prevention, and emerging research trends in NTM infections. Key findings reveal the global prevalence of NTM infections, their diverse clinical presentations affecting respiratory and extra-pulmonary systems, and the diagnostic challenges addressed by advances in microbiological, radiological, and immunological methods. Treatment complexities, especially drug resistance and patient adherence, are discussed, along with the vulnerability of special populations. The importance of early detection and management is underscored. Prospects in NTM research, including genomics, diagnostics, drug development, and multidisciplinary approaches, promise to enhance our understanding and treatment of these infections. This review encapsulates the multifaceted nature of NTM infections, offering a valuable resource for clinicians, researchers, and public health professionals.

Non-tuberculous mycobacterial skin and soft tissue infections in the Northern Territory, Australia, 1989-2021

BACKGROUND

A previous review demonstrated that the majority of NTM infections in the Northern Territory (NT) are pulmonary in nature [1], however skin and soft tissue (SST) are likely the next most common sites of disease. The current epidemiology of NTM SST infections across the NT is not known. We aimed to establish the current and historical incidence rates, and the organisms involved.

METHODS

All NTM cases reported to the Centre for Disease Control in Darwin from 1989-2021 were retrospectively reviewed.

RESULTS

226 NTM notifications were reviewed. 73 (32%) cases were SST infections. The incidence of SST cases increased over the study period. Female cases were more common (p=0·002). Disease occurred across a wide age range (1-85 years). Only 16% of cases occurred in Aboriginal individuals which may reflect immunological factors requiring further investigation. Many cases had no clear provocation, but localised skin trauma was the most common risk factor. The most common organism identified was M. fortuitum (41%). Diagnosis was often delayed, with a median time to diagnosis of 69 days (IQR=31-149). Most cases (60%) underwent surgical intervention with adjunctive anti-mycobacterial medical therapy.

CONCLUSION

NTM SST incidence rates increased over the study period. NTM SST infections are a rare but important differential diagnosis for non-healing cutaneous wounds.

Disseminated Nontuberculous Mycobacterial Infection in a Tertiary Referral Hospital in South Korea: A Retrospective Observational Study

PURPOSE

Disseminated nontuberculous mycobacterial (D-NTM) disease occurs primarily in immunocompromised hosts. However, these cases have rarely been reported in South Korea. This study aimed to describe the clinical manifestations, disease course, and underlying immune deficiencies of patients with D-NTM disease.

MATERIALS AND METHODS

We retrospectively reviewed the cases of D-NTM disease from January 2005 to December 2019 at a tertiary referral hospital in South Korea. D-NTM disease was defined as a bloodstream infection or infection of two or more non-contiguous body organs with species identification.

RESULTS

Of the 53342 mycobacterial samples from 23338 patients, extrapulmonary NTM was detected in 104 patients, and 3 (2.9%) were diagnosed with D-NTM disease. Mycobacterium avium was isolated from two patients, while M. abscessus subspecies abscessus was identified in one. The patients were aged between 18 and 25 years, and two patients were male. All patients were immunocompromised - one received lung transplantation, one was diagnosed with anhidrotic ectodermal dysplasia with T-cell immune deficiency, and one had monocytopenia and mycobacterial infection syndrome associated with GATA2 mutations. All patients underwent a standard macrolide-based regimen for >5 months, and their sputum tested negative. However, one patient died of bacterial sepsis, while the other two survived.

CONCLUSION

D-NTM disease is rare in a tertiary referral center in South Korea. They occur primarily in immunocompromised patients at a relatively young age. Careful investigation of the underlying immune status is required when treating patients with D-NTM disease.

Nontuberculous mycobacterial myositis in dermatomyositis with long-term use of immunosuppressant: a case report

Inflammatory myopathies, such as polymyositis and dermatomyositis, are systemic inflammatory disorders that affect skeletal muscles and internal organs. The treatment of inflammatory myopathies usually involves long-term use of high doses of steroids and/or immunosuppressants, making patients susceptible to opportunistic infections. Unfortunately, infections are a leading cause of morbidity and mortality in patients with inflammatory myopathies. Musculoskeletal nontuberculous mycobacterial infections are rare. Nontuberculous mycobacterial infections are easily overlooked owing to their rarity, leading to delayed diagnosis and treatment, indolent clinical course, and difficulty isolating the pathogen. Nontuberculous mycobacterial infections are a growing health concern because of their increasing incidence and the need for prolonged treatment. In patients with connective tissue diseases, immunosuppressant use may lead to an increased risk of nontuberculous mycobacterial infection with a poor prognosis, which highlights the need for early diagnosis and treatment. Herein, we report the case of a 59-year-old man diagnosed with dermatomyositis, who had prolonged use of immunosuppressants and developed a disseminated soft tissue infection in both thighs caused by Mycobacterium abscessus. Multimodal images were obtained using magnetic resonance imaging, ultrasonography, and computed tomography. A strong suspicion of possible combined opportunistic infections and appropriate staining is essential in diagnosing nontuberculous mycobacterial myositis.

Treatment of non-tuberculosis mycobacteria skin infections

Non-tuberculosis mycobacteria (NTM) skin infections have become increasingly prevalent in recent years, presenting a unique challenge in clinical management. This review explored the complexities of NTM infections localized to the superficial tissues and provided valuable insights into the optimal therapeutic strategies. The antibiotic selection should base on NTM species and their susceptibility profiles. It is recommended to adopt a comprehensive approach that considers the unique characteristics of superficial tissues to improve treatment effectiveness and reduce the incidence of adverse reactions, infection recurrence, and treatment failure. Infection control measures, patient education, and close monitoring should complement the treatment strategies to achieve favorable outcomes in managing NTM skin infections. Further efforts are warranted to elucidate factors and mechanisms contributing to treatment resistance and relapse. Future research should focus on exploring novel treatment options, innovative drug development/delivery platforms, and precise methodologies for determining therapeutic duration. Longitudinal studies are also needed to assess the long-term safety profiles of the integrated approaches.

Novel Synergies and Isolate Specificities in the Drug Interaction Landscape of Mycobacterium abscessus

Mycobacterium abscessus infections are difficult to treat and are often considered untreatable without tissue resection. Due to the intrinsic drug-resistant nature of the bacteria, combination therapy of three or more antibiotics is recommended. A major challenge in treating M. abscessus infections is the absence of a universal combination therapy with satisfying clinical success rates, leaving clinicians to treat infections using antibiotics lacking efficacy data. We systematically measured drug combinations in M. abscessus to establish a resource of drug interaction data and identify patterns of synergy to help design optimized combination therapies. We measured 191 pairwise drug combination effects among 22 antibacterials and identified 71 synergistic pairs, 54 antagonistic pairs, and 66 potentiator-antibiotic pairs. We found that commonly used drug combinations in the clinic, such as azithromycin and amikacin, are antagonistic in the lab reference strain ATCC 19977, whereas novel combinations, such as azithromycin and rifampicin, are synergistic. Another challenge in developing universally effective multidrug therapies for M. abscessus is the significant variation in drug response between isolates. We measured drug interactions in a focused set of 36 drug pairs across a small panel of clinical isolates with rough and smooth morphotypes. We observed strain-dependent drug interactions that cannot be predicted from single-drug susceptibility profiles or known drug mechanisms of action. Our study demonstrates the immense potential to identify synergistic drug combinations in the vast drug combination space and emphasizes the importance of strain-specific combination measurements for designing improved therapeutic interventions.

A Rare Case of Osteomyelitis of an Ankle Caused by Mycobacterium chelonae

Mycobacterium chelonae, a rapidly growing nontuberculous mycobacterium, is usually described as a causative agent of soft tissue infections (postsurgical, posttraumatic, posttransplantation, postinjection, catheter infection, etc.), but only rarely as a cause of osteomyelitis. The authors describe a case report of a 72-year-old man with osteomyelitis of the talus. Initially, the infection was assessed as a soft tissue infection, without any osteolytic changes on the X-ray. After cultivation with subsequent targeted molecular typing of the rpoB gene, M. chelonae was identified from the affected tissue. The bone involvement was subsequently detected on MRI and confirmed histologically with findings of the granulomatous tissue and acid-fast bacilli. The patient was initially treated intravenously with a combination of tigecycline, amikacin, and moxifloxacin for 4 weeks, after which the oral combination of doxycycline and moxifloxacin continued. Identification of the infecting pathogen using molecular typing thus helped to establish the correct diagnosis and represents a rarely described case of osteomyelitis caused by M. chelonae.

A case of mediastinal abscess and infected aortic aneurysm caused by dissemination of Mycobacterium abscessus subsp. massiliense pulmonary disease

An 81-year-old man was admitted to our hospital because of fever and malaise that had persisted for 3 months. The patient had undergone two aortic valve replacements, 10 and 5 years previously, because of aortic valve regurgitation and infectious endocarditis. He also had had asymptomatic Mycobacterium abscessus complex (MABC) pulmonary disease for the two previous years. Contrast-enhanced computed tomography showed a mediastinal abscess and an ascending aortic aneurysm. Mycobacterium abscessus subsp. massiliense was cultured from his blood, suggesting the aortic aneurysm was secondary to infection of an implanted device. After enlargement over only a few days, a leakage of contrast medium to the mediastinal abscess was found on computed tomography. The patient was diagnosed with rupture of an infectious aortic aneurysm, and emergency aortic replacement and drainage of the mediastinal abscess were successful. The patient was treated with several antibiotics, including meropenem, amikacin, and clarithromycin, and his general condition improved. Cultures from both the mediastinal abscess and a pericardial patch that was placed at the time of surgery 5 years previously revealed MABC. In our case, the infected aortic aneurysm most likely resulted from MABC pulmonary disease rather than from previous intraoperative contamination. This route of infection is rare. Physicians should be aware of the possibility of dissemination and subsequent infection of implants related to MABC pulmonary disease.

Dual Infection of an Open Fracture Caused by Mycobacterium setense and Clostridium celerecrescens

Infections caused by Mycobacterium setense or Clostridium celerecrescens are extremely rare. In this report, for the first time a dual infection with these two pathogens is described. An 18-year-old female suffered multiple injuries, including an open comminuted fracture of the right humeral diaphysis after falling from a fifth-floor balcony in January 2019. Five months after the accident, a fistula appeared in the scar, reaching the bone tissue. M. setense and C. celerecrescens were cultured from sinus swabs and subsequently from perioperative samples. The patient was initially treated with a combination of intravenous antibiotics (ATBs): imipenem, amikacin, and ciprofloxacin. One month after the fracture fixation with a titanium nail, C. celerecrescens was again detected; therefore, metronidazole was added to the therapy. A triple combination of oral (PO) ATBs (trimethoprim–sulfamethoxazole, moxifloxacin, and metronidazole) followed, 8 weeks after the initial intravenous therapy. C. celerecrescens was cultured again two times, most recently in November 2019, when surgical debridement was supplemented by the topical administration of cancellous bone impregnated with vancomycin. Signs of bone healing were found at follow-ups and ATB treatment was finished in March 2020 after a total of 9 months of therapy. To this day, there have been no signs of reinfection. This case thus illustrates the need for a combination of systemic and individualized local therapy in the treatment of complicated cases of dual infections with rare pathogens.

Manifestations of cutaneous mycobacterial infections in patients with inborn errors of IL-12/IL-23-IFNγ immunity

Background

Inborn errors of IL-12/IL-23-IFNγ immunity underlie Mendelian susceptibility to mycobacterial diseases (MSMD), a group of immunodeficiencies characterized by a highly selective susceptibility to weakly virulent strains of mycobacteria, such as non-tuberculous mycobacteria (NTM) and bacillus Calmette-Guérin (BCG). Cutaneous mycobacterial infections are common in MSMD and may represent a red flag for this immunodeficiency.

Objectives

We present a case series of four paediatric patients with MSMD, specifically with IFNγR1 and STAT1 deficiencies, and cutaneous NTM/BCG infections to increase awareness of this immunodeficiency, which may, in some cases, be intercepted by the dermatologist and thus timely referred to the immunologist.

Materials & Methods

Clinical, laboratory and genetic investigations of the four paediatric patients with MSMD are presented.

Results

All four presented patients experienced early complications after BCG vaccination. Two patients suffered recurrent mycobacteriosis, one patient experienced delayed BCG reactivation, and one patient died of disseminated avian mycobacteriosis. The dermatological manifestation in these patients included destructive nasal ulcerations, scrofuloderma of various sites and lupus vulgaris. All patients had a normal basic immune phenotype.

Conclusion

The presented cases demonstrate that NTM/BCG infections in otherwise seemingly immunocompetent patients should raise suspicion of MSMD. This is of utmost importance as specific therapeutic approaches, such as IFNγ treatment or haematopoietic stem cell transplantation, may be employed to improve the disease outcome.

Mycobacterium smegmatis Skin Infection Following Cosmetic Procedures: Report of Two Cases

Mycobacterium smegmatis is an acid-fast bacillus of rapidly growing mycobacteria (RGM) of nontuberculous mycobacteria (NTM). M. smegmatis was considered nonpathogenic to humans until 1986, when the first patient was linked to the infection. To date, fewer than 100 cases have been reported in the literature, mainly related to various surgical procedures. Herein, we report two immunocompetent patients who acquired M. smegmatis infection following cosmetic procedures. Due to the rarity of M. smegmatis infection in routine clinical practice, it is challenging for medical providers to diagnose and treat patients with M. smegmatis infection. M. smegmatis infection should be considered for patients with chronic skin and soft tissue infections at the injection site or surgical site following cosmetic procedures. Histological findings, pathogen identification by molecular testing or bacterial culture are required to make a definitive diagnosis. Medical providers should raise awareness of M. smegmatis infection for patients with chronic skin and soft tissue infections after cosmetic procedures. Stringent sterile procedures for surgical instruments, supplies, and environments should be enforced.

Clinical characteristics and the diagnostic role of molecular tests in musculoskeletal infections caused by nontuberculous Mycobacterium: a single-center experience

PURPOSE

We retrospectively investigated NTM musculoskeletal infections to understand the clinical characteristics as well as the diagnostic performance of molecular tests as a useful supplementary test.

METHODS

A retrospective cohort study was conducted from January 2016 to December 2019. Intraoperative specimens for culture and pathological analysis were obtained during surgery under sterile conditions. AdvanSure TB/NTM real-time PCR (LG Life Sciences, Seoul, Korea) and PCR-reverse blot hybridization assay (REBA, REBA Myco-ID; YD Diagnostics, Yongin, Republic of Korea) was performed directly from tissue specimens for the rapid and accurate identification of 20 mycobacterial species.

RESULTS

A series of 24 patients was identified during the study period. Agricultural/aquatic exposure were predisposing factors in 9 patients, trauma in 4 patients, but no predisposing host factor was identified for 11 patients. Twenty-two patients presented with tenosynovitis and two with arthritis with substantial delays between initial presentation of symptoms and microbiologic diagnosis, with a median of 147 days (range 5-396 days). Pathologic tissue examination of musculoskeletal NTM infections was positive for chronic granulomatous inflammation in 18 cases. Fifteen were positive in the culture study, and nine were positive only in the molecular study using tissue specimens. All 6 M. ulcerans/M. marinum isolates were identified only by PCR.

CONCLUSIONS

This study is an important reminder that NTM infections should be a part of the differential diagnosis in patients with chronic musculoskeletal infections refractory to regular treatment. Although molecular test cannot replace the conventional smear and culture methods, it can be used as a useful supplementary test especially in diagnosing M. marinum infection.

A refractory tenosynovitis of the wrist: a case report

Background

Mycobacterium malmoense is a species of slow-growing nontuberculous mycobacteria. It causes mostly pulmonary infections or lymphadenitis in children, but is increasingly encountered in isolated tenosynovitis in adults. Diagnosis is often delayed because of the rarity of the condition and the difficulty of culturing the bacteria.

Case presentation

We report on a rare association of seronegative polyarthritis with infectious nontuberculous mycobacteria tenosynovitis. A 65-year-old Caucasian female was referred to our clinic because of persisting tenosynovitis of the finger flexor tendons of her right hand, despite two previous synovectomies. She also reported bilateral shoulder and left wrist pain. Paraclinical investigations showed slightly elevated inflammatory parameters. Ultrasound showed synovitis of metacarpophalangeal joints of the right hand and right knee, and a bilateral subacromial bursitis. Hand magnetic resonance imaging also revealed an erosive carpal synovitis. Bacteriological analysis of the second tenosynovectomy specimen showed no growths in aerobic and anaerobic cultures. An additional synovial fluid analysis of the wrist joint was negative for mycobacteria and crystals. Seronegative polyarthritis was suspected, but the initiated immunosuppressive treatment with prednisolone and methotrexate resulted in no clinical improvement of the tenosynovitis. Yet the other joints responded well, and the inflammatory parameters normalized. The immunosuppression was later stopped because of side effects. Due to massive worsening of the tenosynovitis, a third synovectomy was performed. Mycobacterium malmoense was identified on biopsy, leading to the diagnosis of infectious tenosynovitis. At this point, we started an antituberculous therapy, with incomplete response. A combination of antimicrobial and immunosuppressive treatment finally led to the desired clinical improvement.

Conclusion

The treatment of nontuberculous mycobacteria tenosynovitis is not well established, but combining antibiotics with surgical debridement is probably the most adequate approach. Our case highlights the importance of having a high clinical suspicion of an atypical infection in patients with inflammatory tenosynovitis not responding to usual care.

A Case of Nasopharyngeal Mycobacteriosis with Bony Erosion of the External Skull Base

Primary nasopharyngeal mycobacteriosis is a rare disease. We present a case in which skull base bone erosion appeared and was alleviated during the course of the treatment. Bone complications occur in osteoarticular mycobacteriosis, but their occurrence in primary nasopharyngeal mycobacteriosis has not been reported. A 77-year-old immunocompromised Asian woman presented with a right occipitotemporal headache. An ulcerative mass covered with a thick yellowish discharge was found in the roof and posterior walls of the right nasopharynx. Because histopathological examination indicated the presence of mycobacterial infection, we began using antituberculosis medication for the treatment because of the possibility of primary nasopharyngeal tuberculosis. However, this was followed by glossopharyngeal and vagus nerve paralysis. Computed tomography (CT) showed a diffuse enhancing mucosal irregularity in the nasopharynx with bony erosion of the external skull base. Deep tissue biopsy was repeated to differentiate it from malignant lesions, and drainage of pus from the right nasopharynx was confirmed. Subsequently, the headache, neurological findings, and the yellowish discharge disappeared, and the bony erosion of the external skull base was alleviated. Surgical intervention should also be considered for drug-resistant mycobacteriosis. We concluded that mycobacteriosis should also be considered apart from carcinoma even if CT shows a diffuse enhancing mucosal irregularity with bone destruction in the nasopharynx.

Autophagy and Host Defense in Nontuberculous Mycobacterial Infection

Autophagy is critically involved in host defense pathways through targeting and elimination of numerous pathogens via autophagic machinery. Nontuberculous mycobacteria (NTMs) are ubiquitous microbes, have become increasingly prevalent, and are emerging as clinically important strains due to drug-resistant issues. Compared to Mycobacterium tuberculosis (Mtb), the causal pathogen for human tuberculosis, the roles of autophagy remain largely uncharacterized in the context of a variety of NTM infections. Compelling evidence suggests that host autophagy activation plays an essential role in the enhancement of antimicrobial immune responses and controlling pathological inflammation against various NTM infections. As similar to Mtb, it is believed that NTM bacteria evolve multiple strategies to manipulate and hijack host autophagy pathways. Despite this, we are just beginning to understand the molecular mechanisms underlying the crosstalk between pathogen and the host autophagy system in a battle with NTM bacteria. In this review, we will explore the function of autophagy, which is involved in shaping host–pathogen interaction and disease outcomes during NTM infections. These efforts will lead to the development of autophagy-based host-directed therapeutics against NTM infection.

Current Molecular Therapeutic Agents and Drug Candidates for Mycobacterium abscessus

Mycobacterium abscessus has been recognised as a dreadful respiratory pathogen among the non-tuberculous mycobacteria (NTM) because of misdiagnosis, prolonged therapy with poor treatment outcomes and a high cost. This pathogen also shows extremely high antimicrobial resistance against current antibiotics, including the anti-tuberculosis agents. Therefore, current chemotherapies require a long curative period and the clinical outcomes are not satisfactory. Thus, there is an urgent need for discovering and developing novel, more effective anti-M. abscessus drugs. In this review, we sum the effectiveness of the current anti-M. abscessus drugs and drug candidates. Furthermore, we describe the shortcomings and difficulties associated with M. abscessus drug discovery and development.

Photo-damage promoted by tetra-cationic palladium(II) porphyrins in rapidly growing mycobacteria

Antimicrobial photodynamic therapy (aPDT) has gained prominence in microbiology, especially in treating non-invasive infections. Diseases such as mycobacteriosis, which causes localized infections and has a slow treatment, tend to be future targets for this type of technology. Therefore, this study aimed to explore the action of two isomeric Pd(II)-porphyrins on fast-growing mycobacterial strains (RGM). Tetra-cationic porphyrins (4-PdTPyP and 3-PdTPyP) were synthesized and applied against standard strains of Mycobacteroides abscessus subsp. abscessus (ATCC 19977), Mycolicibacterium fortuitum (ATCC 6841), Mycolicibacterium smegmatis (ATCC 700084), and Mycobacteroides abscessus subsp. massiliense (ATCC 48898). Reactive oxygen species (ROS) scavengers were used in an attempt to determine possible ROS produced by the photosensitizers (PS) under study. Moreover, the impact of porphyrin on the mycobacterial surface was further evaluated by atomic force microscopy (AFM), and we observed significant damage on cells walls and altered nanomechanical and electrostatic adhesion properties. The results presented herein show that the positively charged porphyrin at the meta position (3-PdTPyP) was the most efficient PS against the RGM strains, and its bactericidal activity was proven in two irradiation sessions, with singlet oxygen species being the main ROS involved in this process. This study demonstrated the therapeutic potential of porphyrins, especially the 3-PdTPyP derivative.

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

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

Approach to the diagnosis and treatment of non-tuberculous mycobacterial disease

Non-tuberculous mycobacteria (NTM) is a collective name given to a group of more than 190 species of Mycobacterium. The clinical presentation for most NTM infections is non-specific, often resulting in delayed diagnosis. Further complicating matters is that NTM organisms can be difficult to isolate. Medications used to treat NTM infection can be difficult for patients to tolerate, and prolonged courses of anti-mycobacterial therapy are often required for adequate suppression or eradication. Herein, we review different NTM syndromes, appropriate diagnostic tests, and treatment regimens.

A case report of wrist synovial infection due to Mycobacterium jacuzzii, Iran

Background

Mycobacterium jacuzzii (M. jacuzzii) was first isolated in 2003 by insertion of breast implants in Tel Aviv, Israel. In this case report, we describe our experience in detection of M. jacuzzii using phenotypic and genotypic test of wrist synovial sample.

Case presentation

A 73-year-old woman complained of pain and swelling in the right wrist for 4 months. Her body temperature was 37–38 °C, and symptoms, such as pain, swelling, and some movement limitation, were reported. Clinical laboratory parameters showed an elevated C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), and white blood cells (WBC) count. The sequences of hsp65, rpoB, 16S rDNA, and sodA genes indicated very high homology to M. jacuzzii.

Conclusion

We report a case of synovial infection caused by M. jacuzzii in a patient with severe wrist pain in Iran, who was treated with amikacin, levofloxacin, and ethambutol. The outcomes of treatment after 8 months were positive, and no recurrence of infection was reported in the patient.

Epidemiology, diagnosis & treatment of non-tuberculous mycobacterial diseases

Non-tuberculous mycobacteria (NTM) are ubiquitously present in the environment, but NTM diseases occur infrequently. NTM are generally considered to be less virulent than Mycobacterium tuberculosis, however, these organisms can cause diseases in both immunocompromised and immunocompetent hosts. As compared to tuberculosis, person-to-person transmission does not occur except with M. abscessus NTM species among cystic fibrosis patients. Lung is the most commonly involved organ, and the NTM-pulmonary disease (NTM-PD) occurs frequently in patients with pre-existing lung disease. NTM may also present as localized disease involving extrapulmonary sites such as lymph nodes, skin and soft tissues and rarely bones. Disseminated NTM disease is rare and occurs in individuals with congenital or acquired immune defects such as HIV/AIDS. Rapid molecular tests are now available for confirmation of NTM diagnosis at species and subspecies level. Drug susceptibility testing (DST) is not routinely done except in non-responsive disease due to slowly growing mycobacteria ( M. avium complex, M. kansasii) or infection due to rapidly growing mycobacteria, especially M. abscessus. While the decision to treat the patients with NTM-PD is made carefully, the treatment is given for 12 months after sputum culture conversion. Additional measures include pulmonary rehabilitation and correction of malnutrition. Treatment response in NTM-PD is variable and depends on isolated NTM species and severity of the underlying PD. Surgery is reserved for patients with localized disease with good pulmonary functions. Future research should focus on the development and validation of non-culture-based rapid diagnostic tests for early diagnosis and discovery of newer drugs with greater efficacy and lesser toxicity than the available ones.

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

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

Current and future management of non-tuberculous mycobacterial pulmonary disease (NTM-PD) in the UK

A rising number of non-tuberculous mycobacterial (NTM) isolates are being identified in UK clinical practice. There are many uncertainties around the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD), including its epidemiology, diagnosis, treatment and prevention. Regional variations in how patients with NTM-PD are managed reflects the lack of standardised pathways in the UK. Service optimisation and multidisciplinary working can improve the quality of care for patients with NTM-PD, including (1) better identification of patients at risk of NTM-PD and modification of risk factors where applicable; (2) standardisation of reference laboratory testing to offer clinicians access to accurate and prompt information on NTM species and drug sensitivities; (3) development of recognised specialist NTM nursing care; (4) standardisation of NTM-PD imaging strategies for monitoring of treatment and disease progression; (5) establishment of a hub-and-spoke model of care, including clear referral and management pathways, dedicated NTM-PD multidisciplinary teams, and long-term patient follow-up; (6) formation of clinical networks to link experts who manage diseases associated with NTM; (7) enabling patients to access relevant support groups that can provide information and support for their condition; and (8) development of NTM research groups to allow patient participation in clinical trials and to facilitate professional education.