Clinical efficacy and safety of multidrug therapy including thrice weekly intravenous amikacin administration for Mycobacterium abscessus pulmonary disease in outpatient settings: a case series

The epidemiology of pulmonary Mycobacterium abscessus species in Japanese population

BACKGROUND

Mycobacterium abscessus species (MABS) is now a most virulent rapidly growing mycobacteria (RGM), and the rapid increase of MABS was recently observed worldwide, including in Japan. Thus, we gathered evidences of the presence of pulmonary MABS in Japanese population from Japanese articles.

METHODS

we searched studies that addressed the isolation of pulmonary non-tuberculous Mycobacteria (NTM) or MABS from clinical respiratory specimens in Japan.

RESULTS

the ratio of MABS to NTM was 3.04% (95% confidence interval [CI]: 2.51-3.68), found using the meta-analysis of single proportions. The estimated mean age of patients infected with MABS was 67.72 years (95% CI: 65.41-70.02), found using the meta-analysis of single means. The estimated proportion of females, never smoker, and the co-infection with Mycobacterium avium complex (MAC) was 66.75% (95% CI: 59.23-73.50), 67.57% (95% CI: 62.43-72.32), and 36.74% (95% CI: 25.30-49.90), respectively. The characteristics of MABS in Japan were considerably different from that in Europe and United States from the perspective of age, gender, and complications, wherein the patients in these countries tended to be younger, had lower number of females, and had more occurrences of hereditary diseases, including cystic fibrosis (CF).

CONCLUSION

we hypothesized that the characteristics of MABS in the Japanese were involved in those of non-CF MABS, and the distribution of gender and age of MABS were similar to that of MAC in the Japanese.

Nontuberculous Mycobacterial Infections in Pediatric Solid Organ Transplant and Hematopoietic Cell Transplant Recipients

The diagnosis of nontuberculous mycobacterial infections is challenging in pediatric solid organ transplant and hematopoietic cell transplant recipients due to the absence of specific clinical manifestations, limitations of sampling, prolonged times for culture and identification, and difficulty discerning colonization from clinical disease. Treatment is dependent on the nontuberculous mycobacterial species, disease type, and pattern of drug resistance. Treatment of nontuberculous mycobacterial infections involves prolonged durations of therapy using multiple medications, which are limited by toxicities and drug-drug interactions.

[A pharmacologic approach to treatment of Mycobacterium abscessus pulmonary disease]

Mycobacterium abscessus is a fast-growing non-tuberculous mycobacteria complex causing pulmonary infections, comprising the subspecies abscessus, massiliense and bolletii. Differences are based predominantly on natural inducible macrolide resistance, active in most Mycobacterium abscessus spp abscessus species and in Mycobacterium abscessus spp bolletii but inactive in Mycobacterium abscessus spp massiliense. Therapy consists in long-term treatment, combining multiple antibiotics. Prognosis is poor, as only 40% of patients experience cure. Pharmacodynamic and pharmacokinetic data on M. abscessus have recently been published, showing that therapy ineffectiveness might be explained by intrinsic bacterial resistance (macrolides…) and by the unfavorable pharmacokinetics of the recommended antibiotics. Other molecules and inhaled antibiotics are promising.

The synergetic effect of sitafloxacin-arbekacin combination in the Mycobacterium abscessus species

Mycobacterium abscessus species (MABS) is the most commonly isolated rapidly growing mycobacteria (RGM) and is one of the most antibiotic-resistant RGM with rapid progression, therefore, treatment of MABS is still challenging. We here presented a new combination treatment with sitafloxacin that targeted rough morphotypes of MABS, causing aggressive infections. Thirty-four clinical strains of MABS were isolated from various clinical samples at the Juntendo university hospital from 2011 to 2020. The susceptibility to a combination of sitafloxacin and antimicrobial agents was compared to that of the antimicrobial agents alone. Out of 34 MABS, 8 strains treated with sitafloxacin-amikacin combination, 9 of sitafloxacin-imipenem combination, 19 of sitafloxacin-arbekacin combination, and 9 of sitafloxacin-clarithromycin combination showed synergistic effects, respectively. Sitafloxacin-arbekacin combination also exhibited the synergistic effects against 10 of 22 Mycobacterium abscessus subspecies massiliense (Mma) strains and 8 of 11 Mycobacterium abscessus subspecies abscessus (Mab) strains, a highly resistant subspecies of MABS. The sitafloxacin-arbekacin combination revealed more synergistic effects in rough morphotypes of MABS (p = 0.008). We demonstrated the synergistic effect of the sitafloxacin-arbekacin combination against MABS. Further, this combination regimen might be more effective against Mab or rough morphotypes of MABS.

Meeting the challenges of NTM-PD from the perspective of the organism and the disease process: innovations in drug development and delivery

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) poses a substantial patient, healthcare, and economic burden. Managing NTM-PD remains challenging, and factors contributing to this include morphological, species, and patient characteristics as well as the treatment itself. This narrative review focusses on the challenges of NTM-PD from the perspective of the organism and the disease process. Morphological characteristics of non-tuberculous mycobacteria (NTM), antimicrobial resistance mechanisms, and an ability to evade host defences reduce NTM susceptibility to many antibiotics. Resistance to antibiotics, particularly macrolides, is of concern, and is associated with high mortality rates in patients with NTM-PD. New therapies are desperately needed to overcome these hurdles and improve treatment outcomes in NTM-PD. Amikacin liposome inhalation suspension (ALIS) is the first therapy specifically developed to treat refractory NTM-PD caused by Mycobacterium avium complex (MAC) and is approved in the US, EU and Japan. It provides targeted delivery to the lung and effective penetration of macrophages and biofilms and has demonstrated efficacy in treating refractory MAC pulmonary disease (MAC-PD) in the Phase III CONVERT study. Several other therapies are currently being developed including vaccination, bacteriophage therapy, and optimising host defences. Newly developed antibiotics have shown potential activity against NTM-PD and include benzimidazole, delamanid, and pretomanid. Antibiotics commonly used to treat other infections have also been repurposed for NTM-PD, including clofazimine and bedaquiline. Data from larger-scale studies are needed to determine the potential of many of these therapies for treating NTM-PD.

Mycobacterium abscessus subspecies abscessus infection associated with cosmetic surgical procedures: Cases series

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Mycobacterium abscessus is a drug-resistant nontuberculous mycobacterium (NTM).

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Cutaneous & subcutaneous NTM infections post-cosmetic surgery are poorly diagnosed.

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Initial surgical evaluation facilitates early suspicion of M. abscessus infection.

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Rapidly evolving infection & negative culture/antibiotic response are indicators.

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Amikacin, imipenem, & clarithromycin combination may treat M. abscessus infection.

Background

Mycobacterium abscessus is one of the most pathogenic and drug-resistant opportunistic microorganisms among the nontuberculous mycobacteria (NTM) involved in skin and soft tissue infections (SSTI) associated with cosmetic surgical procedures. However, NTM infection is often wrongly diagnosed initially causing prolonged suffering. Here is described the author’s experience working with patients who developed M. abscessus SSTI after cosmetic procedures.

Methods

Patients who developed NTM infection after undergoing cosmetic procedures, and who presented at the Hospital Metropolitano and Hospital Vozandes (Quito, Ecuador) between 2013–2016. A review of patient medical records was performed.

Results

Five patients with culture proven M. abscessus subspecies abscessus SSTI after cosmetic surgeries were identified. All patients were treated with aggressive surgical debridement and antibiotics.

Conclusions

A rapidly spreading wound infection presenting two or more weeks after a cosmetic procedure that fails to respond to standard antimicrobial therapy should raise suspicion for NTM infection. Samples for acid-fast bacilli smear, cultures, and PCR from infected tissue should be taken. Surgical drainage and debridement are recommended along with a long course of antibiotics. In the absence of clinical trials, a combination of amikacin, imipenem, and clarithromycin may be an adequate initial treatment for M. abscessus subspecies abscessus SSTI in immunocompetent patients.

Treatment of Nontuberculous Mycobacterial Pulmonary Disease: An Official ATS/ERS/ESCMID/IDSA Clinical Practice Guideline

Nontuberculous mycobacteria (NTM) represent over 190 species and subspecies, some of which can produce disease in humans of all ages and can affect both pulmonary and extrapulmonary sites. This guideline focuses on pulmonary disease in adults (without cystic fibrosis or human immunodeficiency virus infection) caused by the most common NTM pathogens such as Mycobacterium avium complex, Mycobacterium kansasii, and Mycobacterium xenopi among the slowly growing NTM and Mycobacterium abscessus among the rapidly growing NTM. A panel of experts was carefully selected by leading international respiratory medicine and infectious diseases societies (ATS, ERS, ESCMID, IDSA) and included specialists in pulmonary medicine, infectious diseases and clinical microbiology, laboratory medicine, and patient advocacy. Systematic reviews were conducted around each of 22 PICO (Population, Intervention, Comparator, Outcome) questions and the recommendations were formulated, written, and graded using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. Thirty-one evidence-based recommendations about treatment of NTM pulmonary disease are provided. This guideline is intended for use by healthcare professionals who care for patients with NTM pulmonary disease, including specialists in infectious diseases and pulmonary diseases.

Treatment of nontuberculous mycobacterial pulmonary disease: an official ATS/ERS/ESCMID/IDSA clinical practice guideline

Nontuberculous mycobacteria (NTM) represent over 190 species and subspecies, some of which can produce disease in humans of all ages and can affect both pulmonary and extrapulmonary sites. This guideline focuses on pulmonary disease in adults (without cystic fibrosis or human immunodeficiency virus infection) caused by the most common NTM pathogens such as Mycobacterium avium complex, Mycobacterium kansasii, and Mycobacterium xenopi among the slowly growing NTM and Mycobacterium abscessus among the rapidly growing NTM. A panel of experts was carefully selected by leading international respiratory medicine and infectious diseases societies (ATS, ERS, ESCMID, IDSA) and included specialists in pulmonary medicine, infectious diseases and clinical microbiology, laboratory medicine, and patient advocacy. Systematic reviews were conducted around each of 22 PICO (Population, Intervention, Comparator, Outcome) questions and the recommendations were formulated, written, and graded using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. Thirty-one evidence-based recommendations about treatment of NTM pulmonary disease are provided. This guideline is intended for use by healthcare professionals who care for patients with NTM pulmonary disease, including specialists in infectious diseases and pulmonary diseases.

In vitro efficacy of combinations of eight antimicrobial agents against Mycobacteroides abscessus complex

OBJECTIVES

A standard treatment regimen against Mycobacteroides abscessus complex (MABC) infections has not yet been established, making MABC difficult to treat successfully. In this study, we sought to develop an active ingredient for the clinical treatment of MABC infections.

METHODS

We screened 102 MABC strains isolated from clinical specimens using DNA sequence analysis with the housekeeping genes hsp65 and rpoB. Drug susceptibility testing was performed against two subspecies-Mycobacteroides abscessus subsp. abscessus (M. abscessus) and Mycobacteroides abscessus subsp. massiliense (M. massiliense)-using eight antimicrobial agents (clarithromycin, amikacin, doxycycline, imipenem, linezolid, moxifloxacin, faropenem, and rifampicin). The combined efficacy of the antimicrobial agents was investigated using a checkerboard method.

RESULTS

We identified 51 isolates as M. abscessus, 46 as M. massiliense, and five as others. Most of the M. abscessus isolates (83.0 %) exhibited inducible resistance to clarithromycin via the expression of the erm(41) gene. Combinations of imipenem with linezolid, moxifloxacin, and rifampicin exhibited additive effects against 81.0 %, 40.7 %, and 26.9 % of M. abscessus, respectively, and against 54.5 %, 69.2 %, and 30.8 % of M. massiliense, respectively.

CONCLUSIONS

These results demonstrated the potential efficacy of a regimen containing imipenem against M. abscessus and M. massiliense infections.

M ycobacterium abscessus pulmonary disease: individual patient data meta-analysis

Treatment of Mycobacterium abscessus pulmonary disease (MAB-PD), caused by M. abscessus subsp. abscessus, M. abscessus subsp. massiliense or M. abscessus subsp. bolletii, is challenging.We conducted an individual patient data meta-analysis based on studies reporting treatment outcomes for MAB-PD to clarify treatment outcomes for MAB-PD and the impact of each drug on treatment outcomes. Treatment success was defined as culture conversion for ≥12 months while on treatment or sustained culture conversion without relapse until the end of treatment.Among 14 eligible studies, datasets from eight studies were provided and a total of 303 patients with MAB-PD were included in the analysis. The treatment success rate across all patients with MAB-PD was 45.6%. The specific treatment success rates were 33.0% for M. abscessus subsp. abscessus and 56.7% for M. abscessus subsp. massiliense For MAB-PD overall, the use of imipenem was associated with treatment success (adjusted odds ratio (aOR) 2.65, 95% CI 1.36-5.10). For patients with M. abscessus subsp. abscessus, the use of azithromycin (aOR 3.29, 95% CI 1.26-8.62), parenteral amikacin (aOR 1.44, 95% CI 1.05-1.99) or imipenem (aOR 7.96, 95% CI 1.52-41.6) was related to treatment success. For patients with M. abscessus subsp. massiliense, the choice among these drugs was not associated with treatment outcomes.Treatment outcomes for MAB-PD are unsatisfactory. The use of azithromycin, amikacin or imipenem was associated with better outcomes for patients with M. abscessus subsp. abscessus.

Safety and effectiveness of low-dose amikacin in nontuberculous mycobacterial pulmonary disease treated in Toronto, Canada

Background

Treatment guidelines suggest either a low-dose or high-dose approach when prescribing amikacin for nontuberculous mycobacterial pulmonary disease (NTM PD), but data supporting the low-dose approach are limited. The purpose of this study was to describe the safety and efficacy of the use of a low-dose of intravenous amikacin in a cohort of patients with NTM PD.

Methods

We retrospectively reviewed all patients with NTM PD who received amikacin at our institution between July 1, 2003 and February 28, 2017. Demographics, clinical, microbiological and radiological data, indication and dose of amikacin, and adverse drug effects were recorded.

Results

A total of 107 patients received a regimen containing amikacin for a median (IQR) of 7 (4–11) months. Seventy (65.4%) were female and the mean age (SD) was 58.3 (14.9) years. Amikacin was started at a median dose of 9.9 (2.5) mg/kg/day. Ototoxicity was observed in 30/77 (39%) patients and it was related to female sex (OR 4.96, 95%CI 1.24–19.87), and total dose of amikacin per bodyweight (OR 1.62, 95%CI 1.08–2.43). Patients of East Asian ethnicity were less likely to develop ototoxicity (0.24, 95%CI 0.06–0.95). Out of 96 patients who received amikacin for more than 3 months, 65 (67.7%) experienced symptom improvement and 30/62 (49.2%) converted their sputum to culture negative within a year.

Conclusions

Patients with NTM PD treated with low-dose intravenous amikacin frequently developed ototoxicity, which was associated with female sex, and total dose of amikacin per bodyweight. Physicians should carefully consider dose, treatment duration, and long term prognosis in balancing risks and benefits of intravenous amikacin in NTM PD.

Sitafloxacin-Containing Regimen for the Treatment of Refractory Mycobacterium avium Complex Lung Disease

Background

Sitafloxacin (STFX) exhibits potent activity against Mycobacterium avium complex (MAC) in both in vitro and in vivo experiments. However, limited data are available for the clinical efficacy and adverse effects of STFX and the susceptibility of refractory MAC lung disease (MAC-LD) to the drug. Therefore, this study was aimed at evaluating the clinical efficacy and safety of an STFX-containing regimen for the treatment of refractory MAC-LD.

Methods

We retrospectively evaluated treatment outcomes of 31 patients with refractory MAC-LD, who received an STFX-containing regimen for ≥4 weeks between January 2010 and July 2017. Refractory MAC-LD was defined as persistent positive sputum cultures for >6 months of macrolide-based standard therapy.

Results

Clarithromycin resistance (minimum inhibitory concentration [MIC] ≥32 μg/mL) was identified in 15 patients (48%). Twelve months after receiving the STFX-containing regimen, 26% and 19% of patients showed symptomatic and radiological responses, respectively. Although STFX-associated adverse effects were noted in 9 patients, their severity was grade 1 (National Cancer Institute Common Terminology Criteria); only 1 patient discontinued STFX because of suspected gastrointestinal disturbance. Negative sputum culture conversion was achieved in 7 patients (23%). Both univariate and multivariate logistic regression analyses revealed that surgery, low STFX MIC (≤1 μg/mL), and macrolide resistance were significant predictors of negative sputum culture conversion.

Conclusions

Our results demonstrate that STFX may be effective in one-fourth of patients with refractory MAC-LD. Prospective larger studies that include the analyses of MAC are needed to determine the clinical efficacy of STFX against refractory MAC-LD.

Antimicrobial resistance in Mycobacterium abscessus complex isolated from patients with skin and soft tissue infections at a tertiary teaching hospital in Taiwan

Background

Mycobacterium abscessus complex (MABC) is the most common non-tuberculous mycobacterium that causes complicated skin and soft tissue infections (cSSTIs). The selection of antimycobacterial agents for successful treatment of such infections is a critical issue.

Objectives

To investigate the antimicrobial susceptibility patterns of MABC isolates from skin and soft tissue to a variety of antimycobacterial agents.

Methods

Sixty-seven MABC isolates were collected and partial gene sequencing of secA1, rpoB and hsp65 was used to classify them into three subspecies: M. abscessus subsp. abscessus (MAB), M. abscessus subsp. massiliense (MMA) and M. abscessus subsp. bolletii (MBO). The MICs of 11 antimycobacterial agents for these 67 isolates were determined using a broth microdilution method and commercial Sensititre RAPMYCOI MIC plates, as recommended by CLSI.

Results

In total, 28 MAB, 38 MMA and 1 MBO were isolated from patients with cSSTIs at our hospital. Most MABC strains were resistant to ciprofloxacin, doxycycline, imipenem, linezolid, minocycline, moxifloxacin and trimethoprim/sulfamethoxazole. In addition, most MABC strains were intermediately susceptible or resistant to cefoxitin. Eighteen of the 28 MABs and 1 MBO isolate harboured the T28 polymorphism in the erm(41) gene. Two of the 38 MMA isolates had an rrl A2059G point mutation. Most of the MABC strains were susceptible to amikacin and tigecycline.

Conclusions

In Taiwan, amikacin, clarithromycin and tigecycline have good activity against MMA and MAB erm(41) C28 sequevar isolates, whereas amikacin and tigecycline, rather than clarithromycin, have good activity against both MBO and MAB erm(41) T28 sequevar isolates. Clinical trials are warranted to correlate these data with clinical outcomes.

Clinical features of infection caused by non-tuberculous mycobacteria: 7 years' experience

INTRODUCTION

Non-tuberculous mycobacteria (NTM) are ubiquitous organisms associated with various infections. The aim of the study was to determine the most relevant clinical characteristics of NTM during the 7-year period.

METHODOLOGY

A retrospective study of NTM infections was conducted between January 2009 and December 2016. The American Thoracic Society/Infectious Disease Society of America criteria were used to define cases of pulmonary or an extrapulmonary site.

RESULTS

A total of 85 patients were included in the study. Pulmonary cases predominated 83/85 (98%), while extrapulmonary NTM were present in 2/95 (2%) patients. Overall, ten different NTM species were isolated. The most common organisms were slow-growing mycobacteria (SGM) presented in 70/85 (82.35%) patients. Isolated SGM strains were Mycobacterium avium complex (MAC) in 25/85 (29.41%) patients, M. xenopi in 20/85 (23.53%) patients, M. kansasii in 15/85 (17.65%) patients and M. peregrinum and M. gordonae in 5/85 (5.88%) patients each. Isolated rapid-growing mycobacteria (RGM) strains were M. abscessus in 8/85 (9.41%) patients, M. fortuitum in 4/85 (4.71%) patients and M. chelonae in 3/85 (3.53%) patients. Almost all patients (98%; 83/85) had comorbidities. Among 75 (88.24%) patients who completed follow-up, 59 (69.41%), 10 (11.76%) and 6 (7%), were cured, experienced relapse and died, respectively.

CONCLUSION

In the present study, pulmonary NTM infections were more frequent compared to extrapulmonary disease forms. SGM were most common isolates with MAC pulmonary disease the most frequently found. Comorbidities have an important role in NTM occurrence. Further investigation should focus on an NTM drug susceptibility testing.

Systematic Review and Meta-analyses of the Effect of Chemotherapy on Pulmonary Mycobacterium abscessus Outcomes and Disease Recurrence

In pharmacokinetic/pharmacodynamic models of pulmonary Mycobacterium abscessus complex, the recommended macrolide-containing combination therapy has poor kill rates. However, clinical outcomes are unknown. We searched the literature for studies published between 1990 and 2017 that reported microbial outcomes in patients treated for pulmonary M. abscessus disease. A good outcome was defined as sustained sputum culture conversion (SSCC) without relapse. Random effects models were used to pool studies and estimate proportions of patients with good outcomes. Odds ratios (OR) and 95% confidence intervals (CI) were computed. Sensitivity analyses and metaregression were used to assess the robustness of findings. In 19 studies of 1,533 patients, combination therapy was administered to 508 patients with M. abscessus subsp. abscessus, 204 with M. abscessus subsp. massiliense, and 301 with M. abscessus with no subspecies specified. Macrolide-containing regimens achieved SSCC in only 77/233 (34%) new M. abscessus subsp. abscessus patients versus 117/141 (54%) M. abscessus subsp. massiliense patients (OR, 0.108 [95% CI, 0.066 to 0.181]). In refractory disease, SSCC was achieved in 20% (95% CI, 7 to 36%) of patients, which was not significantly different across subspecies. The estimated recurrent rates per month were 1.835% (range, 1.667 to 3.196%) for M. abscessus subsp. abscessus versus 0.683% (range, 0.229 to 1.136%) for M. abscessus subsp. massiliense (OR, 6.189 [95% CI, 2.896 to 13.650]). The proportion of patients with good outcomes was 52/223 (23%) with M. abscessus subsp. abscessus versus 118/141 (84%) with M. abscessus subsp. massiliense disease (OR, 0.059 [95% CI, 0.034 to 0.101]). M. abscessus subsp. abscessus pulmonary disease outcomes with the currently recommended regimens are atrocious, with outcomes similar to those for extensively drug-resistant tuberculosis. Therapeutically, the concept of nontuberculous mycobacteria is misguided. There is an urgent need to craft entirely new treatment regimens.

Mycobacterium abscessus Complex Infections in Children: A Review

PURPOSE OF REVIEW

Infections in children with Mycobacterium abscessus complex represent a particular challenge for clinicians. Increasing incidence of these infections worldwide has necessitated focused attention to improve both diagnostic as well as treatment modalities. Published medical literature was reviewed, with emphasis on material published in the past 5 years.

RECENT FINDINGS

Increasing availability of new diagnostic tools, such as matrix-assisted laser desorption ionization-time of flight mass spectrometry and custom PCRs, has provided unique insights into the subspecies within the complex and improved diagnostic certainty. Microbiological review of all recent isolates at the University of Minnesota Medical Center was also conducted, with description of the antimicrobial sensitivity patterns encountered in our center, and compared with those published from other centers in the recent literature. A discussion of conventional antimicrobial treatment regimens, alongside detailed description of the relevant antimicrobials, is derived from recent publications. Antimicrobial therapy, combined with surgical intervention in some cases, remains the mainstay of pediatric care. Ongoing questions remain regarding the transmission mechanics, immunologic vulnerabilities exploited by these organisms in the host, and the optimal antimicrobial regimens necessary to enable a reliable cure. Updated treatment guidelines based on focused clinical studies in children and accounting especially for the immunocompromised children at greatest risk are very much needed.

The efficacy, safety, and feasibility of inhaled amikacin for the treatment of difficult-to-treat non-tuberculous mycobacterial lung diseases

Background

In multidrug regimens, including an intravenous aminoglycoside (e.g. amikacin [AMK]) is recommended for difficult-to-treat non-tuberculous mycobacterial (NTM) lung diseases. We aimed to evaluate the efficacy, safety, and feasibility of inhaled AMK therapy in patients with difficult-to-treat NTM lung diseases in a retrospective chart review.

Methods

The study population consisted of patients with NTM lung diseases who received combination therapy, including inhaled AMK therapy, at Keio University Hospital (Tokyo, Japan), from January 2014 through May 2016. A total of 26 cases, consisting of 23 Mycobacterium avium complex (MAC) and three Mycobacterium abscessus complex (MABC) infections cases, were included in this study. The efficacy, safety, and feasibility of inhaled AMK therapy were retrospectively investigated. The Research Ethics Committee of Keio University Hospital approved this study, and informed consent was obtained from all patients.

Results

All 26 patients were culture-positive at enrolment. Twenty-three of the 26 patients (88.5%), including 21/23 MAC patients (91.3%) and 2/3 MABC patients (66.7%), were administered inhaled AMK therapy for >3 months. The proportion of patients who had clinical symptoms, including, cough and sputum, declined after inhalation AMK therapy. Ten of the 23 patients (43.5%) who received AMK inhalation, including 8/21 MAC (38.1%) and 2/2 MABC patients (100%), showed sputum conversion, defined as at least three consecutive negative sputum cultures. Seven of the 23 patients, including, 5/21 MAC and 2/2 MABC patients, showed improvements in high-resolution computed tomography imaging of the chest. In addition, the serum AMK trough levels before the second inhalation were <1.2 μg/mL in all 26 patients, with no occurrence of severe adverse events, such as renal toxicity. One patient (3.8%) experienced auditory toxicity, in the form of tinnitus. However, this symptom was reversible, after temporary interruption of AMK, the patient was able to safely resume the therapy.

Conclusions

Inhaled AMK therapy is an effective and feasible therapy for difficult-to-treat NTM lung disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2665-5) contains supplementary material, which is available to authorized users.