Investigation of Mycobacterium abscessus outbreak among cystic fibrosis patients, Hawaii 2012

Genomic epidemiology of Mycobacterium abscessus at an adult cystic fibrosis programme reveals low potential for healthcare-associated transmission

Rationale

Nontuberculous mycobacteria (NTM) has been reported to be transmitted between people with cystic fibrosis (CF) attending CF centres. A suspected Mycobacterium abscessus outbreak was investigated at the University of Texas Southwestern (UTSW) Adult CF Program using a combination of pathogen genomic sequencing and epidemiologic methods. The objectives of the present study were to apply the Healthcare-Associated Links in Transmission of NTM (HALT NTM) study to investigate the occurrence of potential healthcare-associated transmission and/or acquisition of NTM among people with CF infected with genetically similar NTM isolates.

Methods

Whole-genome sequencing of respiratory M. abscessus isolates from 50 people with CF receiving care at UTSW was performed to identify genetically similar isolates. Epidemiologic investigation, comparison of respiratory and environmental isolates, and home residence watershed mapping were studied.

Measurements and main results

Whole-genome sequencing analysis demonstrated seven clusters of genetically similar M. abscessus (four ssp. abscessus and three ssp. massiliense). Epidemiologic investigation revealed potential opportunities for healthcare-associated transmission within three of these clusters. Healthcare environmental sampling did not recover M. abscessus, but did recover four human disease-causing species of NTM. No subjects having clustered infections lived in the same home residence watershed. Some subjects were infected with more than one M. abscessus genotype, both within and outside of the dominant circulating clones.

Conclusions

Healthcare-associated person-to-person transmission of M. abscessus appears to be rare at this centre. However, polyclonal infections of M. abscessus species and subspecies, not originating from the endemic hospital environment, suggest multiple shared modes of acquisition outside the healthcare setting.

Prospective healthcare-associated links in transmission of nontuberculous mycobacteria among people with cystic fibrosis (pHALT NTM) study: Rationale and study design

BACKGROUND

Healthcare-associated acquisition and transmission of nontuberculous mycobacteria (NTM) among people with cystic fibrosis (pwCF) has been described, and remains a concern for both patients and providers. This report describes the design of a prospective observational study utilizing the standardized epidemiologic investigation toolkit for healthcare-associated links in transmission of NTM among pwCF.

METHODS

This is a parallel multi-site study of pwCF who have infections with respiratory NTM isolates and receive healthcare within a common CF Care Center. Participants have a history of one or more NTM positive airway cultures and have been identified as having NTM infections suggestive of a possible outbreak within a single Center, based on NTM isolate genomic analysis. Participants are enrolled in the study over a 3-year period. Primary endpoints are identification of shared healthcare-associated source(s) among pwCF in a Center, identification of healthcare environmental dust and water biofilm NTM isolates that are genetically highly-related to respiratory isolates, and identification of common home of residence watersheds among pwCF infected with clustered isolates. Secondary endpoints include characterization of healthcare-associated transmission and/or acquisition modes and settings as well as description of incidence and prevalence of healthcare-associated environmental NTM species/subspecies by geographical region.

DISCUSSION

We hypothesize that genetically highly-related isolates of NTM among pwCF cared for at the same Center may arise from healthcare sources including patient-to-patient transmission and/or acquisition from health-care environmental dust and/or water biofilms. This study design utilizes a published, standardized, evidence-based epidemiologic toolkit to facilitate confidential, independent healthcare-associated NTM outbreak investigations within CF Care Centers. This study will facilitate real-time, rapid detection and mitigation of healthcare-associated NTM outbreaks to reduce NTM risk, inform infection prevention and control guidelines, and characterize the prevalence and origin of NTM outbreaks from healthcare-associated patient-to-patient transmission and/or environmental acquisition. This study will systematically characterize human disease causing NTM isolates from serial collection of healthcare environmental dust and water biofilms and define the most common healthcare environmental sources harboring NTM biofilms.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05686837.

Treatable traits and challenges in the clinical management of non-tuberculous mycobacteria lung disease in people with cystic fibrosis

INTRODUCTION

Over the last ten years an increasing prevalence and incidence of non-tuberculous mycobacteria (NTM) has been reported among patients with cystic fibrosis (CF) Viviani (J Cyst Fibros, 15(5):619-623, 2016). NTM pulmonary disease has been associated with negative clinical outcomes and often requires pharmacological treatment. Although specific guidelines help clinicians in the process of diagnosis and clinical management, the focus on the multidimensional assessment of concomitant problems is still scarce.

MAIN BODY

This review aims to identify the treatable traits of NTM pulmonary disease in people with CF and discuss the importance of a multidisciplinary approach in order to detect and manage all the clinical and behavioral aspects of the disease. The multidisciplinary complexity of NTM pulmonary disease in CF requires careful management of respiratory and extra-respiratory, including control of comorbidities, drug interactions and behavioral factors as adherence to therapies.

CONCLUSIONS

The treatable trait strategy can help to optimize clinical management through systematic assessment of all the aspects of the disease, providing a holistic treatment for such a multi-systemic and complex condition.

Environmental Sources and Transmission of Nontuberculous Mycobacteria

The field of environmental nontuberculous mycobacteria (NTM) is benefiting from a new era of genomics that has catapulted our understanding of preferred niches, transmission, and outbreak investigations. The ability to forecast environmental features that promote or reduce environmental NTM prevalence will greatly improve with coordinated environmental sampling and by elevating the necessity for uniform disease notifications. Studies that synergize environmental biology, isolate notifications, and comparative genomics in prospective, longitudinal studies, particularly during climate changes and weather events, will be useful to solve longstanding NTM public health quandaries.

Phylogenomics of nontuberculous mycobacteria respiratory infections in people with cystic fibrosis

Nontuberculous mycobacteria (NTM) can cause severe pulmonary disease in people with cystic fibrosis (pwCF). These infections present unique challenges for diagnosis and treatment, prompting a recent interest in understanding NTM transmission and pathogenesis during chronic infection. Major gaps remain in our knowledge regarding basic pathogenesis, immune evasion strategies, population dynamics, recombination potential, and the evolutionary implications of host and antibiotic pressures of long-term NTM infections in pwCF. Phylogenomic techniques have emerged as an important tool for tracking global patterns of transmission and are beginning to be used to ask fundamental biological questions about adaptation to the host during pathogenesis. In this review, we discuss the burden of NTM lung disease (NTM-LD), highlight the use of phylogenomics in NTM research, and address the clinical implications associated with these studies.

Potential Cross-Transmission of Mycobacterium abscessus among Non-Cystic Fibrosis Patients at a Tertiary Hospital in Japan

Mycobacterium abscessus (M. abscessus) is a highly antimicrobial-resistant pathogen that causes refractory pulmonary disease. Recently, the possibility of M. abscessus cross-transmission among cystic fibrosis (CF) patients has been reported. CF is rare in Asia, but M. abscessus pulmonary disease is common. Therefore, we investigated the possibility of M. abscessus cross-transmission in a Japanese hospital setting. Of 104 M. abscessus isolates, 25 isolates from 24 patients were classified into four clusters based on their variable number of tandem repeat profiles and were subjected to whole-genome sequencing (WGS). The epidemiological linkages among our patients were investigated by integrating the WGS data of previously reported nosocomial outbreak-related M. abscessus clinical isolates in the United Kingdom and the United States. Eight transmissible clusters (TCs) were identified. The United Kingdom and United States isolates were assigned to four clusters (TC1, TC2, TC5, and TC8) and one cluster (TC3), respectively. A total of 12 isolates from our hospital belonged to 4 clusters (TC4, TC5, TC6, and TC7). Epidemiological linkage analysis inferred direct or indirect transmission between patients in our hospital in TC4 and TC5 but not in TC6 and TC7. In TC5, the single nucleotide polymorphism distance between isolates from Japanese and United Kingdom patients was less than 21; however, there was no contact. This study revealed that genetically closely related isolates exist, even in non-CF patients. However, the transmission route remains unclear, and further research is warranted to clarify whether cross-transmission is involved. IMPORTANCE Although the possibility of Mycobacterium abscessus (M. abscessus) cross-transmission in cystic fibrosis (CF) patients has often been reported, it is not clear whether similar events have occurred in Asian non-CF patients. Whole-genome sequencing analysis of M. abscessus isolates from Fukujuji Hospital in Japan indicated that genetically closely related M. abscessus isolates exist. In addition, according to epidemiological linkage analysis, some clusters were suspected of direct or indirect transmission between patients within our hospital. However, the transmission route of M. abscessus remains unclear, because interestingly, one cluster showed a single nucleotide polymorphism distance of less than 21 from the United Kingdom isolates, but no epidemiological linkage was identified.

Investigating Nontuberculous Mycobacteria Transmission at the Colorado Adult Cystic Fibrosis Program

Rationale: Healthcare-associated transmission of nontuberculous mycobacteria (NTM) among people with cystic fibrosis (pwCF) has been investigated at CF centers worldwide, with conflicting conclusions. We investigated transmission at the Colorado Adult CF Program. Objectives: To systematically investigate healthcare-associated transmission and/or acquisition of NTM to determine similarity among respiratory and environmental isolates, and to compare home residence watershed mapping among pwCF having genetically similar NTM isolates. Methods: Whole-genome sequencing of NTM isolates from 80 pwCF was conducted to identify genetically similar isolate clusters (⩽30 SNP differences). Epidemiology, comparison of respiratory and environmental isolates, and home residence watershed mapping were analyzed. Measurements and Main Results: Whole-genome sequencing analysis revealed 11 clusters of NTM [6 Mycobacterium abscessus subspecies (ssp.) abscessus, 1 M. abscessus ssp. massiliense, 2 Mycobacterium avium, and 2 Mycobacterium intracellulare] among pwCF. Epidemiologic investigation demonstrated opportunities for healthcare-associated transmission in two M. abscessus and two M. avium clusters. Respiratory and healthcare environmental isolate comparisons revealed no genetic similarity. Individuals comprising one M. abscessus cluster, with no plausible healthcare-associated transmission, resided in the same watershed. Conclusions: This study suggests healthcare-associated transmission of M. abscessus is rare and includes a report of potential healthcare-associated transmission of M. avium among pwCF. One M. abscessus cluster possibly had common acquisition arising from residing in the same watershed. The presence of genetically similar isolates is insufficient to demonstrate healthcare-associated NTM transmission. Standardizing epidemiologic investigation, combined with environmental sampling and watershed analysis, will improve understanding of the frequency and nature of healthcare-associated NTM transmission among pwCF.

Healthcare-associated links in transmission of nontuberculous mycobacteria among people with cystic fibrosis (HALT NTM) study: Rationale and study design

Background

Healthcare-associated transmission of nontuberculous mycobacteria (NTM) among people with cystic fibrosis (pwCF) has been reported and is of increasing concern. No standardized epidemiologic investigation tool has been published for healthcare-associated NTM outbreak investigations. This report describes the design of an ongoing observational study to standardize the approach to NTM outbreak investigation among pwCF.

Methods

This is a parallel multi-site study of pwCF within a single Center who have respiratory NTM isolates identified as being highly-similar. Participants have a history of positive airway cultures for NTM, receive care within a single Center, and have been identified as part of a possible outbreak based on genomic analysis of NTM isolates. Participants are enrolled in the study over a 3-year period. Primary endpoints are identification of a shared healthcare-associated encounter(s) among patients in a Center and identification of environmental isolates that are genetically highly-similar to respiratory isolates recovered from pwCF. Secondary endpoints include characterization of potential transmission modes and settings, as well as incidence and prevalence of healthcare-associated environmental NTM species/subspecies by geographical region.

Discussion

We hypothesize that genetically highly-similar strains of NTM among pwCF cared for at the same Center may arise from healthcare sources including patient-to-patient transmission and/or acquisition from environmental sources. This novel study design will establish a standardized, evidence-based epidemiologic investigation tool for healthcare-associated NTM outbreak investigation within CF Care Centers, will broaden the scope of independent outbreak investigations and demonstrate the frequency and nature of healthcare-associated NTM transmission in CF Care Centers nationwide. Furthermore, it will provide valuable insights into modeling risk factors associated with healthcare-associated NTM transmission and better inform future infection prevention and control guidelines. This study will systematically characterize clinically-relevant NTM isolates of CF healthcare environmental dust and water biofilms and set the stage to describe the most common environmental sources within the healthcare setting harboring clinically-relevant NTM isolates.

Trial registration

ClinicalTrials.gov NCT04024423. Date of registry July 18, 2019.

Population Genomics of Mycobacterium abscessus from U.S. Cystic Fibrosis Care Centers

Rationale:Mycobacterium abscessus is a significant threat to individuals with cystic fibrosis (CF) because of innate drug resistance and potential transmission between patients. Recent studies described global dominant circulating clones of M. abscessus, but detailed genomic surveys have not yet been described for the United States. Objectives: We examined the genetic diversity of respiratory M. abscessus isolates from U.S. patients with CF and evaluated the potential for transmission events within CF Care Centers. Methods: Whole-genome sequencing was performed on 558 M. abscessus isolates from 266 patients with CF attending 48 CF Care Centers in 28 U.S. states as part of a nationwide surveillance program. U.S. isolates were also compared with 64 isolate genomes from 13 previous studies to evaluate the prevalence of recently described dominant circulating clones. Results: More than half of study patients with CF and M. abscessus had isolates within four dominant clones; two clones of M. abscessus subspecies (subsp.) abscessus (MAB) and two clones of M. abscessus subsp. massiliense (MMAS). Acquired drug resistance mutations for aminoglycosides and macrolides were rare in the isolate population, and they were not significantly enriched in dominant clones compared with unclustered isolates. For a subset of 55 patients, there was no relationship between dominant clones and diagnosis of active lung disease (P = 1.0). Twenty-nine clusters of genetically similar MAB isolates and eight clusters of genetically similar MMAS isolates were identified. Overall, 28 of 204 (14%) patients with MAB and 15 of 64 (23%) patients with MMAS had genetically isolates similar to those of at least one other patient at the same CF Care Center. Genetically similar isolates were also found between 60 of 204 (29%) patients with MAB and 19 of 64 (30%) patients with MMAS from different geographic locations. Conclusions: Our study reveals the predominant genotypes of M. abscessus and frequency of shared strains between patients in U.S. CF Care Centers. Integrated epidemiological and environmental studies would help to explain the widespread presence of dominant clones in the United States, including the potential for broad distribution in the environment. Single site studies using systematic, evidence-based approaches will be needed to establish the contributions of health care-associated transmission versus shared environmental exposures.

Antibiotic treatment for nontuberculous mycobacteria lung infection in people with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria are mycobacteria, other than those in the Mycobacterium tuberculosis complex, and are commonly found in the environment. Nontuberculous mycobacteria species (most commonly Mycobacterium avium complex and Mycobacterium abscessus) are isolated from the respiratory tract of approximately 5% to 40% of individuals with cystic fibrosis; they can cause lung disease in people with cystic fibrosis leading to more a rapid decline in lung function and even death in certain circumstances. Although there are guidelines for the antimicrobial treatment of nontuberculous mycobacteria lung disease, these recommendations are not specific for people with cystic fibrosis and it is not clear which antibiotic regimen may be the most effective in the treatment of these individuals. This is an update of a previous review.

OBJECTIVES

The objective of our review was to compare antibiotic treatment to no antibiotic treatment, or to compare different combinations of antibiotic treatment, for nontuberculous mycobacteria lung infections in people with cystic fibrosis. The primary objective was to assess the effect of treatment on lung function and pulmonary exacerbations and to quantify adverse events. The secondary objectives were to assess treatment effects on the amount of bacteria in the sputum, quality of life, mortality, nutritional parameters, hospitalizations and use of oral antibiotics.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search: 24 February 2020. We also searched a register of ongoing trials and the reference lists of relevant articles and reviews. Date of last search: 21 March 2019.

SELECTION CRITERIA

Any randomized controlled trials comparing nontuberculous mycobacteria antibiotics to no antibiotic treatment, as well as one nontuberculous mycobacteria antibiotic regimen compared to another nontuberculous mycobacteria antibiotic regimen, in individuals with cystic fibrosis.   DATA COLLECTION AND ANALYSIS: Data were not collected because in the one trial identified by the search, data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

MAIN RESULTS

One completed trial was identified by the searches, but data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

AUTHORS' CONCLUSIONS

This review did not find any evidence for the effectiveness of different antimicrobial treatment for nontuberculous mycobacteria lung disease in people with cystic fibrosis. Until such evidence becomes available, it is reasonable for clinicians to follow published clinical practice guidelines for the diagnosis and treatment of nodular or bronchiectatic pulmonary disease due to Mycobacterium avium complex or Mycobacterium abscessus in patients with cystic fibrosis.

Cystic fibrosis program characteristics associated with adoption of 2013 infection prevention and control recommendations

BACKGROUND

The Cystic Fibrosis (CF) Foundation disseminated an updated guideline for infection prevention and control (IP&C) practices for CF care programs in 2013. Assessing adoption rates of IP&C recommendations is crucial to evaluate their impact.

METHODS

CF care programs provided their written IP&C policies for CF. Policies were analyzed to determine adoption of selected recommendations new in 2013, as well as recommendations made in both 2003 and 2013. Weighted adoption scores were analyzed for association with program characteristics.

RESULTS

The median number of new recommendations adopted by each program was 7 (mean 6.3, range 0-9). The most commonly adopted new recommendations were universal mask use by patients in both inpatient and outpatient settings (85% and 87%, respectively) and contact precautions for CF patients in inpatient and outpatient settings (90% for both). The least frequently adopted new recommendations were the "6-foot rule" in inpatient settings (n = 66, 53%) and auditing disinfection of surfaces in clinic (n = 64, 49%). Larger program size was associated with a higher weighted adoption score (odds ratio [OR] 1.9, P =.02).

CONCLUSIONS

Whereas most programs adopted more than one-half of the selected IP&C recommendations assessed, adoption was variable. Efforts to improve adoption of IP&C recommendations should focus on smaller programs with fewer resources.

Outbreaks of nontuberculous mycobacteria

PURPOSE OF REVIEW

The purpose of this review is to summarize the emerging literature on nontuberculous mycobacteria outbreaks in healthcare settings. As our ability to identify mycobacterial species develops, we are better able to recognize epidemiologic connections and better understand the prevalence and importance of these outbreaks and pseudo-outbreaks in healthcare settings.

RECENT FINDINGS

The number of outbreaks related to nontuberculous outbreaks is increasing because of heightened awareness and better diagnostic tests for species level identification of mycobacteria. Outbreaks in healthcare settings have been related to cardiac surgery, plastic surgery, including medical tourism, colonized humidifiers and heater-cooler devices, imperfect disinfection, and hospital water sources. Mycobacteria have a predilection to form biofilms, are resistant to disinfection and are prevalent in hospital water systems. Patients with structural lung disease like cystic fibrosis patients are at particularly high risk for mycobacterial infection. It has been thought that acquisition in this patient population is from common environmental exposure; however, there is increasing evidence that transmission in this patient population can occur through either direct or indirect patient-to-patient spread.

SUMMARY

Mycobacteria outbreaks in healthcare settings have been underrecognized. As we identify additional clusters of infection with better diagnostic tools and heightened awareness, we will likely need better infection control practices to prevent infections in healthcare settings.

Antagonism between Front-Line Antibiotics Clarithromycin and Amikacin in the Treatment of Mycobacterium abscessus Infections Is Mediated by the whiB7 Gene

Combinations of antibiotics, each individually effective against Mycobacterium abscessus, are routinely coadministered based on the concept that this minimizes the spread of antibiotic resistance. However, our in vitro data contradict this assumption and instead document antagonistic interactions between two antibiotics (clarithromycin and amikacin) used to treat M. abscessus infections. Clinically relevant concentrations of clarithromycin induced increased resistance to both amikacin and itself. The induction of resistance was dependent on whiB7, a transcriptional activator of intrinsic antibiotic resistance that is induced by exposure to many different antibiotics. In M. abscessus, the deletion of whiB7 (MAB_3508c) resulted in increased sensitivity to a broad range of antibiotics. WhiB7 was required for transcriptional activation of genes that confer resistance to three commonly used anti-M. abscessus drugs: clarithromycin, amikacin, and tigecycline. The whiB7-dependent gene that conferred macrolide resistance was identified as erm(41) (MAB_2297), which encodes a ribosomal methyltransferase. The whiB7-dependent gene contributing to amikacin resistance was eis2 (MAB_4532c), which encodes a Gcn5-related N-acetyltransferase (GNAT). Transcription of whiB7 and the resistance genes in its regulon was inducible by subinhibitory concentrations of clarithromycin but not by amikacin. Thus, exposure to clarithromycin, or likely any whiB7-inducing antibiotic, may antagonize the activities of amikacin and other drugs. This has important implications for the management of M. abscessus infections, both in cystic fibrosis (CF) and non-CF patients.

Antibiotic treatment for nontuberculous mycobacteria lung infection in people with cystic fibrosis

BACKGROUND

Nontuberculous mycobacteria are mycobacteria, other than those in the Mycobacterium tuberculosis complex, and are commonly found in the environment. Nontuberculous mycobacteria species (most commonly Mycobacterium avium complex and Mycobacterium abscessus) are isolated from the respiratory tract of approximately 5% to 40% of individuals with cystic fibrosis; they can cause lung disease in people with cystic fibrosis leading to more a rapid decline in lung function and even death in certain circumstances. Although there are guidelines for the antimicrobial treatment of nontuberculous mycobacteria lung disease, these recommendations are not specific for people with cystic fibrosis and it is not clear which antibiotic regimen may be the most effective in the treatment of these individuals. This is an update of a previous review.

OBJECTIVES

The objective of our review was to compare antibiotic treatment to no antibiotic treatment, or to compare different combinations of antibiotic treatment, for nontuberculous mycobacteria lung infections in people with cystic fibrosis. The primary objective was to assess the effect of treatment on lung function and pulmonary exacerbations and to quantify adverse events. The secondary objectives were to assess treatment effects on the amount of bacteria in the sputum, quality of life, mortality, nutritional parameters, hospitalizations and use of oral antibiotics.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search: 02 September 2016.We also searched a register of ongoing trials and the reference lists of relevant articles and reviews. Date of last search: 03 November 2016.

SELECTION CRITERIA

Any randomized controlled trials comparing nontuberculous mycobacteria antibiotics to no antibiotic treatment, as well as one nontuberculous mycobacteria antibiotic regimen compared to another nontuberculous mycobacteria antibiotic regimen, in individuals with cystic fibrosis.   DATA COLLECTION AND ANALYSIS: Data were not collected because in the one trial identified by the search, data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

MAIN RESULTS

One completed trial was identified by the searches, but data specific to individuals with cystic fibrosis could not be obtained from the pharmaceutical company.

AUTHORS' CONCLUSIONS

This review did not find any evidence for the effectiveness of different antimicrobial treatment for nontuberculous mycobacteria lung disease in people with cystic fibrosis. Until such evidence becomes available, it is reasonable for clinicians to follow published clinical practice guidelines for the diagnosis and treatment of nodular or bronchiectatic pulmonary disease due to Mycobacterium avium complex or Mycobacterium abscessus in patients with cystic fibrosis.

Environmental Nontuberculous Mycobacteria in the Hawaiian Islands

Lung disease caused by nontuberculous mycobacteria (NTM) is an emerging infectious disease of global significance. Epidemiologic studies have shown the Hawaiian Islands have the highest prevalence of NTM lung infections in the United States. However, potential environmental reservoirs and species diversity have not been characterized. In this cross-sectional study, we describe molecular and phylogenetic comparisons of NTM isolated from 172 household plumbing biofilms and soil samples from 62 non-patient households and 15 respiratory specimens. Although non-uniform geographic sampling and availability of patient information were limitations, Mycobacterium chimaera was found to be the dominant species in both environmental and respiratory specimens. In contrast to previous studies from the continental U.S., no Mycobacterium avium was identified. Mycobacterium intracellulare was found only in respiratory specimens and a soil sample. We conclude that Hawai’i’s household water sources contain a unique composition of Mycobacterium avium complex (MAC), increasing our appreciation of NTM organisms of pulmonary importance in tropical environments.

In the U.S., the Hawaiian Islands have the highest number of nontuberculous mycobacterial (NTM) lung disease cases per capita. The tropical climate, geographical isolation of the islands, and aquifer water sources may have influence such prevalence. Previous studies suggest that NTM thrive in water biofilms and soil. To broaden our understanding of potential environmental reservoirs and species composition of NTM in the Hawaiian Islands, we sampled environmental sites and examined patient isolates. Our recovery and identification of Mycobacterium chimaera and several other clinically relevant NTM species and the absence of Mycobacterium avium in both the indigenous environment and clinical specimens underscore the need for further studies to define the environmental factors that drive NTM lung disease and species composition in high prevalence locations such as the Hawaiian Islands.

Nontuberculous Mycobacteria in Cystic Fibrosis

Nontuberculous mycobacteria (NTM) are found in approximately 10 % of cystic fibrosis (CF) patients, but only a portion will develop NTM disease. The management of CF lung disease should be optimized, including antibiotic therapy targeted to the individual's usual airway bacteria, prior to considering treatment for NTM lung disease. Those who meet criteria for NTM lung disease may not necessarily require treatment and could be monitored expectantly if symptoms and radiographic findings are minimal. However, the presence of Mycobacterium abscessus complex (MABSC), severe lung disease, and/or anticipated lung transplant should prompt NTM therapy initiation. For CF patients with Mycobacterium avium complex (MAC), recommended treatment includes triple antibiotic therapy with a macrolide, rifampin, and ethambutol. Azithromycin is generally our preferred macrolide in CF as it is better tolerated and has fewer drug-drug interactions. MABSC treatment is more complex and requires an induction phase (oral macrolide and two IV agents including amikacin) as well as a maintenance phase (nebulized amikacin and two to three oral antibiotics including a macrolide). The induction phase may range from one to three months (depending on infection severity, treatment response, and medication tolerability). For both MAC and MABSC, treatment duration is extended 1-year post-culture conversion. However, in patients who do not achieve culture negative status but tolerate therapy, we consider ongoing treatment for mycobacterial suppression and prevention of disease progression.