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

Challenges in achieving the guideline-recommended amikacin level for Mycobacterium avium complex pulmonary disease

Background

The addition of aminoglycosides to a macrolide-based regimen is recommended for refractory Mycobacterium avium complex pulmonary disease (MAC-PD). For intravenous amikacin (AMK) administration three times a week, the ATS/ERS/ESCMID/IDSA guidelines recommend targeting a peak serum concentration of 65-80 µg/mL. However, the feasibility of achieving the guideline-recommended AMK concentration remains unclear.

Methods

From 2018 to 2022, we retrospectively analyzed patients with refractory MAC-PD treated with AMK thrice weekly for ≥3 months combined with an oral regimen of ≥2 drugs, including macrolides. The peak serum concentration and therapeutic effects of AMK were evaluated.

Results

The median age of the 9 patients was 70 years (range: 50-79 years; 2 men and 7 women). The causative organism was M. avium in all cases. All cases demonstrated susceptibility to AMK, which was administered at a median dose of 700 mg/day (15.8 mg/kg/day) for a median duration of 6 months. One patient experienced hearing loss, which led to AMK discontinuation at 4 months. The median AMK peak concentration was 47.1 μg/mL, with a tendency to be higher in the clinical efficacy group compared to the nonefficacy group. None of patient, except one, achieved the target AMK peak concentration.

Conclusions

In this preliminary study, the guideline-recommended AMK concentration for MAC-PD was not achieved in the majority of patients. Due to the small sample size and retrospective design, robust conclusions regarding the association between AMK concentrations and clinical outcomes could not be drawn. Prospective randomized controlled trials are required to better define the optimal AMK concentration for efficacy and safety.

Trial registration

Not applicable.

Multicenter, retrospective cohort study of antimycobacterial treatment-related harms among patients with non-tuberculosis Mycobacterium infections in the United States

Non-tuberculosis mycobacteria (NTM) are extensively drug-resistant organisms that require long-term therapy. The study purpose was to quantify the incidence of and risk factors for antimycobacterial-associated adverse drug events (ADEs) in persons with NTM infections receiving outpatient therapy. A multicenter, retrospective cohort was performed of persons with NTM infections who received antimycobacterial treatment from 2013 to 2024. Inclusion criteria were age ≥18 years, ≥1 month of outpatient treatment, and ≥1 follow-up outpatient visit within 3 months of index encounter. Mycobacterium avium complex and Mycobacterium tuberculosis complex were excluded. The primary outcome was development of pre-specified treatment-related ADE or acute kidney injury (AKI), thrombocytopenia, and/or Clostridioides difficile infection (CDI) through 12 months of therapy. Secondary outcomes included therapy discontinuation due to any treatment-related ADEs. Two hundred patients were included: 14% developed a pre-specified ADE. Mycobacterium abscessus (29%) was the most common pathogen; most initial regimens included a macrolide (54%), systemic aminoglycoside (24%), β-lactam (24%), or tetracycline derivative (22%). The most common pre-specified ADEs were thrombocytopenia (9%), AKI (8%), and CDI (<1%). The median (IQR) time-to-ADE was 25 (18-38) days from initial outpatient regimen; patients who received aminoglycoside- or oxazolidinone-based therapies were more likely to develop a pre-specified ADE (adjOR, 3.9; 95% CI, 1.7-9.2). Therapy discontinuation due to any ADE occurred in 35% of patients; the median (IQR) time-to-any ADE was 32 (21-58) days. ADEs in persons with NTM infections are common and occur near the first month of outpatient treatment. Intensified monitoring and/or use of more tolerable antimycobacterial regimens early in treatment may be an appropriate approach to avoid harms.Treatment of non-tuberculosis mycobacteria is complicated by adverse drug events (ADEs). This work quantified the incidence and time course of pre-determined, clinically relevant ADEs (acute kidney injury, thrombocytopenia, and C. difficile infection), which occurred in 14% of patients within 30 days of outpatient treatment.

Pulmonary nontuberculous mycobacterial infections among women with cystic fibrosis and non-cystic fibrosis bronchiectasis

Nontuberculous mycobacteria (NTM) are ubiquitous, opportunistic pathogens that can cause lung disease in people with non-cystic fibrosis bronchiectasis (NCFB) and cystic fibrosis (CF). The incidence of NTM pulmonary infections and lung disease has continued to increase worldwide over the last decade among both groups. Notably, women with NCFB NTM pulmonary disease (NTM-PD) bear a disproportionate burden with NTM rates increasing in this population as well as having consistently higher incidence of NTM-PD compared to men. In contrast, among people with CF, an overall increased risk among women has not been observed. In the United States, the majority of people with CF are taking highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulators, and these numbers are increasing worldwide. The long-term impact of CFTR modulator medications on NTM infections is not entirely understood. Guidelines for the screening, diagnosis, and management of NTM-PD exist for people with NCFB and CF, but do not consider unique implications relevant to women. This review highlights aspects of NTM-PD among women with NCFB and CF, including the epidemiology of NTM infection, special considerations for treatment, and unmet research needs relevant to women with NTM-PD.

The Long and Winding Road: Three-year Mortality Following Prescription of Multidrug Antibiotic Treatment for Mycobacterium avium complex Pulmonary Disease in United States Medicare Beneficiaries With Bronchiectasis

Background/Aims

Although increased mortality has been reported among people with Mycobacterium avium complex pulmonary disease (MAC-PD), data are limited on survival associated with various antibiotic regimens used to treat MAC-PD. We conducted a comparative analysis of 3-year mortality in Medicare beneficiaries with bronchiectasis using various MAC-PD regimens.

Methods

We included Medicare beneficiaries aged ≥65 years with bronchiectasis (01/2006-12/2014). We limited our cohort to new MAC-PD therapy users. MAC-PD therapy was defined as ≥60-day prescriptions for a macrolide plus ≥1 other MAC-PD antibiotic. Guideline-based therapy (GBT) included a macrolide, ethambutol, and/or rifamycin. Using Cox proportional hazard models, we calculated adjusted hazard ratios (aHR) for death up to 3 years after therapy start between the following groups: (1) 2007 GBT versus non-GBT; (2) 2020 GBT versus non-GBT; and (3) macrolide-ethambutol-rifamycin (3-drug) versus macrolide-ethambutol (2-drug).

Results

We identified 4820 new MAC-PD therapy users, of whom 866 (17.9%) were deceased within 3 years of therapy initiation. Of 3040 (63.1%) beneficiaries prescribed 2007 GBT, 472 (15.5%) were deceased by 3 years, compared to 394 (22.1%) of 1780 (36.9%) prescribed non-GBT (aHR 0.82; 95% confidence interval [CI], .72-.94). We observed a similar trend for 2020 GBT versus non-GBT (aHR 0.81; 95% CI, .70-.94]). Three-year-mortality was similar between those starting 3-drug versus 2-drug regimens (aHR 0.89; 95% CI, .74-1.08]).

Conclusions

Among Medicare new MAC-PD therapy users, 3-year-mortality was higher in those prescribed non-GBT regimens compared to GBT regimens. Whether this finding suggests improved efficacy of GBT and/or differential characteristic of those using non-GBT regimens deserves further study.

Supporting Patients with Nontuberculous Mycobacterial Pulmonary Disease: Ensuring Best Practice in UK Healthcare Settings

Nontuberculous mycobacterial pulmonary disease (NTM-PD) results from opportunistic lung infections by mycobacteria other than Mycobacterium tuberculosis or Mycobacterium leprae species. Similar to many other countries, the incidence of NTM-PD in the United Kingdom (UK) is on the rise for reasons that are yet to be determined. Despite guidelines established by the American Thoracic Society (ATS), the Infectious Diseases Society of America, and the British Thoracic Society, NTM-PD diagnosis and management remain a significant clinical challenge. In this review article, we comprehensively discuss key challenges in NTM-PD diagnosis and management, focusing on the UK healthcare setting. We also propose countermeasures to overcome these challenges and improve the detection and treatment of patients with NTM-PD.

Re-telling the story of aminoglycoside ototoxicity: tales from sub-Saharan Africa

Background

Aminoglycosides, such as Streptomycin, are cheap, potent antibiotics widely used Sub-Saharan Africa. However, aminoglycosides are the commonest cause of ototoxicity. The limited prospective epidemiological studies on aminoglycoside ototoxicity from Sub-Saharan Africa motivated this study to provide epidemiological information on Streptomycin-induced ototoxicity, identify risk factors and predictors of ototoxicity.

Method

A longitudinal study of 153 adults receiving Streptomycin-based anti-tuberculous drugs was done. All participants underwent extended frequency audiometry and had normal hearing thresholds at baseline. Hearing thresholds were assessed weekly for 2 months, then monthly for the subsequent 6 months. Ototoxicity was determined using the ASHA criteria. Descriptive statistics were used to analyze socio-demographic variables. Ototoxicity incidence rate was calculated, and Kaplan-Meier estimate used to determine cumulative probability of ototoxicity. Chi-square test was done to determine parameters associated with ototoxicity and Cox regression models were used to choose the predictors of ototoxicity.

Results

Age of participants was 41.43 ± 12.66 years, with a male-to-female ratio of 1:0.6. Ototoxicity was found in 34.6% of the participants, giving an incidence of 17.26 per 1,000-person-week. The mean onset time to ototoxicity was 28.0 ± 0.47 weeks. By 28th week, risk of developing ototoxicity for respondents below 40 years of age was 0.29, and for those above 40 years was 0.77. At the end of the follow-up period, the overall probability of developing ototoxicity in the study population was 0.74. A significant difference in onset of ototoxicity was found between the age groups: the longest onset was seen in <40 years, followed by 40-49 years, and shortest onset in ≥50 years. Hazard of ototoxicity was significantly higher in participants aged ≥50 years compared to participants aged ≤40 years (HR = 3.76, 95% CI = 1.84-7.65). The probability of ototoxicity at 40 g, 60 g and 80 g cumulative dose of Streptomycin was 0.08, 0.43 and 2.34, respectively. Age and cumulative dose were significant predictors of ototoxicity.

Conclusion

The mean onset time to Streptomycin-induced ototoxicity was 28 weeks after commencement of therapy. Age and cumulative dose can reliably predict the onset of Streptomycin-induced ototoxicity. Medium to long term monitoring of hearing is advised for patients on aminoglycoside therapy.

[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.

Medications and Monitoring in Treatment of Nontuberculous Mycobacterial Pulmonary Disease

In the treatment of nontuberculous mycobacteria (NTM) lung disease, clinicians must consider potential toxicities that may occur as a result of prolonged exposure to a multidrug antibiotic regimen. Frequent clinical and microbiological monitoring is required to assess response and guide treatment duration. This article summarizes toxicity profiles of the antibiotics that are most frequently prescribed for the treatment of NTM lung disease. The role of therapeutic drug monitoring during use of amikacin and linezolid is discussed. The available evidence to guide frequency and extent of medication monitoring during NTM treatment is provided.

Colistin- and amikacin-loaded lipid-based drug delivery systems for resistant gram-negative lung and wound bacterial infections

Antimicrobial resistance (AMR) is a global health issue, which needs to be tackled without further delay. The World Health Organization(WHO) has classified three gram-negative bacteria, Pseudomonas aeruginosa, Klebsiella pneumonia and Acinetobacter baumannii, as the principal responsible for AMR, mainly causing difficult to treat nosocomial lung and wound infections. In this regard, the need for colistin and amikacin, the re-emerged antibiotics of choice for resistant gram-negative infections, will be examined as well as their associated toxicity. Thus, current but ineffective clinical strategies designed to prevent toxicity related to colistin and amikacin will be reported, highlighting the importance of lipid-based drug delivery systems (LBDDSs), such as liposomes, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), as efficient delivery strategies for reducing antibiotic toxicity. This review reveals that colistin- and amikacin-NLCs are promising carriers with greater potential than liposomes and SLNs to safely tackle AMR, especially for lung and wound infections.

Amikacin liposome and Mycobacterium avium complex: A systematic review

INTRODUCTION

The prevalence of Mycobacterium avium complex (MAC) is increasing globally. Macrolide-based multidrug regimens have been recommended as the first-line treatment for patients with MAC pulmonary disease. However, developing macrolide resistance was associated with poor treatment outcomes and increased mortality. In 2018, the U.S. Food and Drug Administration approved liposomal amikacin for inhalation (LAI) to treat refractory MAC pulmonary disease. The current systematic review aimed to evaluate LAI's outcomes and adverse events in MAC pulmonary disease.

METHODS

The systematic search was performed in PubMed/Medline, EMBASE, and the Cochrane Controlled Register of Trials (CENTRAL) up to March 8, 2022. The search terms included Mycobacterium avium complex, MAC, amikacin, and liposomal amikacin.

RESULTS

After reviewing 1284 records, four papers met the inclusion criteria, including three clinical trials and one prospective cohort study. These studies showed that adding LAI to guideline-based therapies can increase sputum culture conversion rate and achieve early sustained (negative sputum culture results for 12 months with treatment) and durable (negative sputum culture results for three months after treatment) negative sputum culture. In addition, extended LAI use was a potential benefit in patients considered refractory to initial treatment. The most prevalent treatment-emergent adverse events (TEAE) reported in the LAI group were the respiratory TEAE.

CONCLUSIONS

LAI could increase the sputum culture conversion rate and achieve early sustainable, durable negative sputum culture. However, additional large-scale research is required to confirm the results.

Identification and drug susceptibility testing of the subspecies of Mycobacterium avium complex clinical isolates in mainland China

OBJECTIVES

The Mycobacterium avium complex (MAC), comprising a series of subspecies, has a worldwide distribution, with differences in drug susceptibility among subspecies. This study aimed to assess the composition of MAC and susceptibility differences among subspecies in mainland China.

METHODS

A total of 287 MAC clinical strains were included in the study. Multitarget sequences were applied to accurately identify subspecies, and a microdilution method was used to evaluate minimum inhibitory concentrations (MICs) among subspecies using Sensititre SLOMYCO plates.

RESULTS

Mycobacterium intracellular (N = 169), Mycobacterium avium (N = 52), Mycobacterium chimaera (N = 22), Mycobacterium marseillense (N = 25), Mycobacterium colombiense (N = 14), Mycobacterium yongonense (N = 4), Mycobacterium vulneris (N = 3) and Mycobacterium timonense (N = 2) were isolated from MAC. Clarithromycin, amikacin and rifabutin showed lower MIC₅₀ and MIC₉₀ values than other drugs, and the resistance rates of clarithromycin, amikacin, linezolid and moxifloxacin were 6.3%, 10.5%, 51.9% and 46.3%, respectively. The resistance rates of clarithromycin and moxifloxacin in the initial treatment group were significantly lower than those in the retreatment group (4.09% vs. 12.94%; 30.41% vs. 75.29%; P < 0.05). Drug susceptibility differences were observed in clarithromycin and moxifloxacin among the five major subspecies (P < 0.05); however, those statistically significant differences disappeared when MACs were divided into two groups according to previous anti-tuberculosis (anti-TB) treatment history.

CONCLUSION

This study revealed that MAC, primarily comprising M. intracellulare, was susceptible to clarithromycin, amikacin and rifabutin. Drug susceptibility among subspecies did not exhibit intrinsic differences in our study. Previous anti-TB treatment patients are more resistant to drugs; thus, attention should be given to those patients in the clinic.

Management of Mycobacterium avium complex and Mycobacterium abscessus pulmonary disease: therapeutic advances and emerging treatments

Nontuberculous mycobacterial pulmonary disease (NTM-PD) remains a challenging condition to diagnose and treat effectively. Treatment of NTM-PD is prolonged, frequently associated with adverse effects and has variable success. In this review, we consider the factors influencing clinicians when treating NTM-PD and discuss outcomes from key studies on the pharmacological management of Mycobacterium avium complex pulmonary disease and M. abscessus pulmonary disease. We highlight issues relating to treatment-related toxicity and provide an overview of repurposed and emerging therapies for NTM-PD.

Sex Differences in the Triad of Acquired Sensorineural Hearing Loss

The triad of noise-generated, drug-induced, and age-related hearing loss is the major cause of acquired sensorineural hearing loss (ASNHL) in modern society. Although these three forms of hearing loss display similar underlying mechanisms, detailed studies have revealed the presence of sex differences in the auditory system both in human and animal models of ASNHL. However, the sexual dimorphism of hearing varies among noise-induced hearing loss (NIHL), ototoxicity, and age-related hearing loss (ARHL). Importantly, estrogen may play an essential role in modulating the pathophysiological mechanisms in the cochlea and several reports have shown that the effects of hormone replacement therapy on hearing loss are complex. This review will summarize the clinical features of sex differences in ASNHL, compare the animal investigations of cochlear sexual dimorphism in response to the three insults, and address how estrogen affects the auditory organ at molecular levels.

Impact of Therapeutic Drug Monitoring on Once-Daily Regimen of Amikacin in Patients With Urinary Tract Infection: A Prospective Observational Study

BACKGROUND

Amikacin is a semisynthetic antibiotic used in the treatment of gram-negative bacterial infections and has a narrow therapeutic index. Although therapeutic drug monitoring is recommended for amikacin, it is not routinely performed because of the use of a less toxic once-daily regimen. Only few studies have evaluated the role of therapeutic drug monitoring in patients treated with amikacin. The objective of our study was to find an association between the pharmacokinetic parameters of amikacin and the time required for a clinical cure, creatinine clearance, and frequency of ototoxicity in patients with urinary tract infection treated for 7 or more days.

METHODS

A prospective study was conducted on patients with urinary tract infections who were administered amikacin for 7 or more days. Blood samples were obtained from the patients to measure the maximum drug concentration (Cmax) and trough concentration (Ctrough). Minimum inhibitory concentration (MIC) values were determined for patients with positive urine cultures. Serum creatinine levels were estimated every 3 days. The auditory assessment was performed using pure tone audiometry at baseline and weekly until the patients were discharged. Levels of amikacin were analyzed using a validated liquid chromatography-tandem mass spectrometry method.

RESULTS

Of 125 patients analyzed, the median time required for a clinical cure was less in the group of patients who achieved a Cmax/MIC ratio ≥8 than it was in those who did not achieve this level [7 versus 8 days (P = 0.02)]. The Ctrough of amikacin was associated with the change in serum creatinine level (P = 0.01) and the incidence of nephrotoxicity (P = 0.004).

CONCLUSIONS

In patients receiving short-term amikacin therapy, Cmax/MIC value can be used to predict the time required for a clinical cure. Ctrough can be used to predict the occurrence of nephrotoxicity in patients receiving amikacin therapy.

Population Pharmacokinetic Analysis of Amikacin for Optimal Pharmacotherapy in Korean Patients with Nontuberculous Mycobacterial Pulmonary Disease

Amikacin is used as a therapy for patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) who are resistant to macrolide antibiotics or have severe symptoms. This study aimed to characterize the pharmacokinetic properties of amikacin in patients with NTM-PD by developing a population pharmacokinetic model and to explore the optimal pharmacotherapy in patients with NTM-PD. For this study, all data were retrospectively collected. The amikacin pharmacokinetic properties were best described by a two-compartment model with first-order elimination. The estimated glomerular filtration rate and body weight were identified as significant covariates for clearance and the volume of distribution, respectively. A model-based simulation was conducted to explore the probability of reaching the target therapeutic range when various dose regimens were administered according to the body weight and renal function. The simulation results indicated that the amikacin dosage should be determined based on the body weight, and for patients who weigh over 70 kg, it is necessary to adjust the dose according to renal function. In conclusion, the optimal pharmacotherapy of amikacin for patients with NTM-PD was recommended based on the population pharmacokinetic model, which is expected to enable the personalization of drug therapy and improve the clinical outcomes of amikacin therapy.

Tablet and web-based audiometry to screen for hearing loss in adults with cystic fibrosis

INTRODUCTION

Individuals with chronic lung disease (eg, cystic fibrosis (CF)) often receive antimicrobial therapy including aminoglycosides resulting in ototoxicity. Extended high-frequency audiometry has increased sensitivity for ototoxicity detection, but diagnostic audiometry in a sound-booth is costly, time-consuming and requires a trained audiologist. This cross-sectional study analysed tablet-based audiometry (Shoebox MD) performed by non-audiologists in an outpatient setting, alongside home web-based audiometry (3D Tune-In) to screen for hearing loss in adults with CF.

METHODS

Hearing was analysed in 126 CF adults using validated questionnaires, a web self-hearing test (0.5 to 4 kHz), tablet (0.25 to 12 kHz) and sound-booth audiometry (0.25 to 12 kHz). A threshold of ≥25 dB hearing loss at ≥1 audiometric frequency was considered abnormal. Demographics and mitochondrial DNA sequencing were used to analyse risk factors, and accuracy and usability of hearing tests determined.

RESULTS

Prevalence of hearing loss within any frequency band tested was 48%. Multivariate analysis showed age (OR 1.127; (95% CI: 1.07 to 1.18; p value<0.0001) per year older) and total intravenous antibiotic days over 10 years (OR 1.006; (95% CI: 1.002 to 1.010; p value=0.004) per further intravenous day) were significantly associated with increased risk of hearing loss. Tablet audiometry had good usability, was 93% sensitive, 88% specific with 94% negative predictive value to screen for hearing loss compared with web self-test audiometry and questionnaires which had poor sensitivity (17% and 13%, respectively). Intraclass correlation (ICC) of tablet versus sound-booth audiometry showed high correlation (ICC >0.9) at all frequencies ≥4 kHz.

CONCLUSIONS

Adults with CF have a high prevalence of drug-related hearing loss and tablet-based audiometry can be a practical, accurate screening tool within integrated ototoxicity monitoring programmes for early detection.

Successful bedaquiline-containing antimycobacterial treatment in post-traumatic skin and soft-tissue infection by Mycobacterium fortuitum complex: a case report

BACKGROUND

Mycobacterium fortuitum complex is a group of rapidly growing nontuberculous mycobacteria (NTM) associated with skin and soft-tissue infections after surgery or trauma. Treatment of NTM is challenging, due to resistance to multiple antimycobacterial agents. Bedaquiline is a diarylquinoline that inhibits mycobacterial ATP-synthase. The drug has recently been approved for the treatment of multidrug-resistant tuberculosis and evidence of its in vitro efficacy against NTM, including Mycobacterium fortuitum complex, has been published.

CASE PRESENTATION

A 20-year-old Caucasian woman with chronic skin and soft tissue infection in the lower leg following a traffic accident in Vietnam underwent a tedious journey of healthcare visits, hospital admissions, empiric antimicrobial treatments, surgical debridement and plastic reconstruction before definite diagnosis of Mycobacterium fortuitum complex-infection was established by culture from a tissue biopsy and targeted antimycobacterial therapy was administered. Histopathological examination revealed granulomatous purulent inflammation, which strongly supported the diagnosis. Genotypic identification was performed and broth microdilution for susceptibility testing showed macrolide resistance. Five weeks of induction treatment with intravenous amikacin, imipenem / cilastin, and oral levofloxacin was administered, followed by all-oral treatment with bedaquiline combined with levofloxacin for four months, which was well-tolerated and led to persistent healing with scars but without signs of residual infection.

CONCLUSIONS

Bedaquiline is a promising novel agent for NTM treatment, although clinical data are limited and trials evaluating efficacy, safety, and resistance of bedaquiline are required. To our knowledge, this is the first reported case of successful in vivo use of bedaquiline for a skin and soft tissue infection caused by Mycobacterium fortuitum complex.