Mycobacterium Avium Complex Isolates Research Articles

2135. Epetraborole in vitro Activity Against Mycobacterium avium complex Recent Clinical Isolates from Japan

Abstract Background Epetraborole (EBO) is a boron-containing, oral inhibitor of bacterial leucyl-tRNA synthetase, an essential enzyme in protein synthesis. EBO demonstrates potent activity against nontuberculous mycobacteria and is currently under clinical development for treatment of treatment-refractory Mycobacterium avium complex (MAC) lung disease. The objective of this study was to evaluate the in vitro activity of EBO against recent MAC isolates from Japan. Methods Minimal inhibitory concentration (MIC) values for EBO, amikacin (AMK), clarithromycin (CLR), rifabutin (RFB), and ethambutol (EMB) were determined using broth microdilution assays according to Clinical and Laboratory Standards Institute M24-A3 guideline (2018) against 110 MAC clinical isolates collected from Japanese patients in 2020. MAC isolates were of respiratory origin and included 55 M. avium and 55 M. intracellulare isolates. Results EBO (MIC) values ranged from 0.25 - 16 µg/mL and the EBO MIC50 and MIC90 were 2 and 4 µg/mL, respectively (Table 1). The CLR MIC range was 0.125 - > 32 µg/mL and included 4 CLR-resistant isolates (MIC ≥ 32 µg/mL). CLR MIC50 and MIC90 were 1 and 4 µg/mL, respectively. All isolates were susceptible to AMK and had an MIC range of 2 - 32 µg/mL; the MIC50 and MIC90 were 8 and 16 µg/mL, respectively. The EMB MIC range was 2 - > 32 µg/mL; the MIC50 and MIC90 were 4 and 16 µg/mL, and the RFB MIC range was ≤0.03 - 2 µg/mL and MIC50 and MIC90 were 0.06 and 0.25 µg/mL. EBO maintained activity with MIC values of 0.25 - 2 µg/mL against the 4 CLR-resistant isolates. Epetraborole and comparator antimicrobial minimum inhibitory concentration values against 110 recent Mycobacterium avium complex clinical isolates from Japan MIC=minimal inhibitory concentration; MIC50=minimal inhibitory concentration for 50% of isolates tested; MIC90=minimal inhibitory concentration for 90% of isolates tested. Conclusion EBO demonstrated potent in vitro activity against 110 recent MAC isolates collected from Japanese patients. Furthermore, EBO demonstrated in vitro activity against CLR-resistant MAC isolates suggesting that CLR-resistance does not impact EBO activity. These data are similar to results obtained against U.S. isolates and support the continued clinical evaluation of the use of EBO in the treatment of MAC lung disease in Japan. Disclosures Tiffany Keepers White, PhD, AN2 Therapeutics: Employee|AN2 Therapeutics: Stocks/Bonds Satoshi Mitarai, MD, PhD, AN2 Therapeutics, Inc.: Grant/Research Support

Phenotypic drug-susceptibility profiles and genetic analysis based on whole-genome sequencing of Mycobacterium avium complex isolates in Thailand.

Mycobacterium avium complex (MAC) infections are a significant clinical challenge. Determining drug-susceptibility profiles and the genetic basis of drug resistance is crucial for guiding effective treatment strategies. This study aimed to determine the drug-susceptibility profiles of MAC clinical isolates and to investigate the genetic basis conferring drug resistance using whole-genome sequencing (WGS) analysis. Drug-susceptibility profiles based on minimum inhibitory concentration (MIC) assays were determined for 38 MAC clinical isolates (12 Mycobacterium avium and 26 Mycobacterium intracellulare). Mutations associated with drug resistance were identified through genome analysis of these isolates, and their phylogenetic relationships were also examined. Drug resistance, based on MIC values, was most commonly observed for moxifloxacin (81.6%), followed by linezolid (78.9%), clarithromycin (44.7%) and amikacin (36.8%). We identified specific mutations associated with resistance to amikacin. These include the rrs mutation at C464T in amikacin intermediate-resistance M. avium, and two mutations at T250A and G1453T in amikacin non-susceptible M. intracellulare. Mutations in rrl at A2058G, A2059C and A2059G were potentially linked to clarithromycin resistance. MAC clinical isolates not susceptible to linezolid exhibited mutations in rplC at G237C and C459T, as well as two rplD mutations at G443A and A489G. GyrB substitution Thr521Ala (T521A) was identified in moxifloxacin non-susceptible isolates, which may contribute to this resistance. A phylogeny of our MAC isolates revealed high levels of genetic diversity. Our findings suggest that the standard treatment regimen for MAC infections using moxifloxacin, linezolid, clarithromycin and amikacin may be driving development of resistance, potentially due to specific mutations. The combination of phenotypic and genotypic susceptibility testing can be valuable in guiding the clinical use of drugs for the treatment of MAC infections.

Species identification and drug susceptibility testing of non-tuberculous mycobacteria by Line Probe Assay in Lambaréné, Gabon—a cross-sectional study

BackgroundNon-tuberculous mycobacteria (NTM) are a group of bacteria that cause rare lung infections and are increasingly recognized as causative agents of opportunistic and device-associated infections in humans. In Gabon, there is a lack of data on NTM species identification and drug susceptibility. The aim of this study was to identify the frequency of NTM species and their genotypic susceptibility pattern to commonly used antibiotics for NTM infections in Gabon.MethodsA cross-sectional study was conducted at the CERMEL TB laboratory from January 2020 to December 2022, NTM subspecies identification and drug susceptibility testing to macrolides and aminoglycosides were performed using the genotype NTM-DR kit.ResultsThe study found that out of 524 culture-positive specimens, 146 (28%) were NTM, with the predominant group being Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MABC). All MAC isolates were fully susceptible to macrolides and aminoglycosides, while five MABC isolates carried mutations indicative of reduced susceptibility to macrolide and aminoglycoside drugs.ConclusionsThese findings suggest that clinicians may use macrolides and aminoglycosides to manage NTM infections caused by MAC, but further investigation is required to determine MABC drug susceptibility.

In Vitro Effect of Three-Antibiotic Combinations plus Potential Antibiofilm Agents against Biofilm-Producing Mycobacterium avium and Mycobacterium intracellulare Clinical Isolates.

Patients with chronic pulmonary diseases infected by Mycobacterium avium complex (MAC) often develop complications and suffer from treatment failure due to biofilm formation. There is a lack of correlation between in vitro susceptibility tests and the treatment of clinical isolates producing biofilm. We performed susceptibility tests of 10 different three-drug combinations, including two recommended in the guidelines, in biofilm forms of eight MAC clinical isolates. Biofilm developed in the eight isolates following incubation of the inoculum for 3 weeks. Then, the biofilm was treated with three-drug combinations with and without the addition of potential antibiofilm agents (PAAs). Biofilm bactericidal concentrations (BBCs) were determined using the Vizion lector system. All selected drug combinations showed synergistic activity, reducing BBC values compared to those treated with single drugs, but BBC values remained high enough to treat patients. However, with the addition of PAAs, the BBCs steadily decreased, achieving similar values to the combinations in planktonic forms and showing synergistic activity in all the combinations and in both species. In conclusion, three-drug combinations with PAAs showed synergistic activity in biofilm forms of MAC isolates. Our results suggest the need for clinical studies introducing PAAs combined with antibiotics for the treatment of patients with pulmonary diseases infected by MAC.

Monotherapy: Key cause of macrolide-resistant Mycobacterium avium complex disease

BackgroundMacrolide-resistant Mycobacterium avium complex (MAC) disease is very difficult to cure. Macrolide-resistance emerges in patients and is largely preventable by appropriate screening and treatment practices. MethodsPatients with macrolide-resistant MAC isolates between March 2019 and March 2022 were retrieved from the mycobacteriology reference laboratory database at Radboudumc, Nijmegen, the Netherlands. Clinical consultation reports were extracted from the database to assess the cause of macrolide resistance. ResultsSixteen patients with macrolide-resistant MAC disease were included, from a total of 815 patients with MAC isolates (2%); Macrolide monotherapy in bronchiectasis or CF was the most frequent cause of development of macrolide-resistance MAC disease (n = 8; 50%). Short (n = 3; mean duration 9 months, range 6–12) or guideline non-compliant (n = 2) treatment regimens and patient non-adherence (n = 2) were other key causes of macrolide-resistance. ConclusionsMacrolide monotherapy after inappropriate screening is the most frequent cause of macrolide-resistant Mycobacterium avium complex disease in the Netherlands. Educational efforts are needed to prevent this.

Accurate subspecies-level identification of clinically significant Mycobacterium avium and Mycobacterium intracellulare by whole-genome sequencing

Whole genome sequencing (WGS) of Mycobacterium avium complex (MAC) isolates in the clinical laboratory setting allows for rapid and reliable subspecies identification of a closely related complex of human pathogens. We developed a bioinformatics pipeline for accurate subspecies identification and tested 74 clinical MAC isolates from various anatomical sites. We demonstrate that reliable subspecies level identification of these common and clinically significant MAC isolates, including M. avium subsp. hominissuis (most dominant in causing lower respiratory tract infections in our cohort), M. avium subsp. avium, M. intracellulare subsp. intracellulare, and M. intracellulare subsp. chimaera, can be achieved by analysis of only two marker genes (rpoB and groEL/hsp65). We then explored the relationship between these subspecies and anatomical site of infection. Further, we conducted an in silico analysis and showed our algorithm also performed well for M. avium subsp. paratuberculosis but failed to consistently identify M. avium subsp. silvaticum and M. intracellulare subsp. yongonense, likely due to a lack of available reference genome sequences; all the 3 subspecies were not found in our clinical isolates and rarely reported to cause human infections. Accurate MAC subspecies identification may provide the tool and opportunity for better understanding of the disease-subspecies dynamics in MAC infections.

Comparative study of in vitro activity of tedizolid and linezolid against Mycobacterium avium complex.

ObjectivesThe aim of this study is to compare the in vitro activity and minimal inhibitory concentration (MIC) distributions of tedizolid and linezolid against Mycobacterium avium complex (MAC) strains using a reference broth microdilution assay and a macrodilution assay with the Bactec-MGIT-960. MethodsA total of 37 clinical isolates of MAC were included in the study. Reference broth microdilution was performed according to CLSI guidelines in a range of concentrations from 64 to 0.064 mg/L. Macrodilution was performed with the Bactec-MGIT-960 system. The cut-off points defined by CLSI for linezolid (resistant: > 16 mg/L, intermediate: 16 mg/L, susceptible: <16 mg/L) were used to define clinical categories of this drug. Essential agreement for both linezolid and tedizolid and categorical agreement for linezolid were defined following FDA criteria. ResultsThe MIC50 (16mg/L) and MIC90 (32mg/L) values for linezolid were identical with both methods. However, the MIC50 and MIC90 of tedizolid by microdilution (4 mg/L and 8 mg/L, respectively) were one twofold dilution higher than by macrodilution (2 mg/L and 4 mg/L, respectively). Ninety-four percent and 2.7% of the strains had MICs of tedizolid ≤4 mg/L and ≤ 0.5 mg/L, respectively, by the reference method. The linezolid macrodilution assay showed a categorical agreement of 40.5%, a minor error rate of 56.7% and a major error rate of 2.7% with respect to the reference method. ConclusionsTedizolid showed higher in vitro activity than linezolid against the tested MAC isolates. Macrodilution using the BD Bactec-MGIT-960 system is a practical approach to determine the susceptibility of MAC strains to tedizolid.

In vitro assessment of 17 antimicrobial agents against clinical Mycobacterium avium complex isolates

BackgroundRecently, Mycobacterium avium complex (MAC) infections have been increasing, especially in immunocompromised and older adults. The rapid increase has triggered a global health concern due to limited therapeutic strategies and adverse effects caused by long-term medication. To provide more evidence for the treatment of MAC, we studied the in vitro inhibitory activities of 17 antimicrobial agents against clinical MAC isolates.ResultsA total of 111 clinical MAC isolates were enrolled in the study and they were identified as M. intracellulare, M. avium, M. marseillense, M. colombiense, M. yongonense, and two isolates could not be identified at the species level. MAC strains had relatively low (0–21.6%) resistance to clarithromycin, amikacin, bedaquiline, rifabutin, streptomycin, and clofazimine, and the resistant rates to isoniazid, rifampin, linezolid, doxycycline, and ethionamide were very high (72.1–100%). In addition, M. avium had a significantly higher resistance rate than that of M. intracellulare for ethambutol (92.3% vs 40.7%, P < 0.001), amikacin (15.4% vs 1.2%, P = 0.049), and cycloserine (69.2% vs 25.9%, P = 0.004).ConclusionsOur results supported the current usage of macrolides, rifabutin, and aminoglycosides in the regimens for MAC infection, and also demonstrated the low resistance rate against new drugs, such as clofazimine, tedizolid, and bedaquiline, suggesting the possible implementation of these drugs in MAC treatment.

Relationship between Resistance to Ethambutol and Rifampin and Clinical Outcomes in Mycobacterium avium Complex Pulmonary Disease.

We evaluated the associations between the in vitro activities of ethambutol and rifampin and clinical outcomes of Mycobacterium avium complex (MAC) pulmonary disease (PD). Among 158 patients with MAC-PD, there was no relationship between high MICs for ethambutol and/or rifampin and treatment failure for MAC-PD. Ethambutol and rifampin resistance was common among MAC isolates (rates of 87% and 59%, respectively), but mutations in embB, rpoB, and rpoC were rare, with detection in only 4% of the drug-resistant MAC isolates.

High rate of reinfection and possible transmission of Mycobacterium avium complex in Northeast Thailand

The Mycobacterium avium complex (MAC) includes two main species of non-tuberculous mycobacteria (NTM), M. avium and Mycobacterium intracellulare. These can cause serious disease, especially in immunocompromised patients. Little information is available concerning genetic diversity of NTM. We used multilocus sequence typing (MLST) based on a highly discriminative gene set to analyze MAC serially isolated from patients to determine the rate of MAC reinfection. Genomic DNA was sequenced from 49 MAC isolates (15 cases comprised of 11 true infections and 4 instances of colonization). More than half of the MAC isolates tested were found to be multidrug resistant. The discriminatory power was assessed of 24 house-keeping genes (fusA, atpD, pheT, glnA, topA, secA, argH, glpK, murC, cya, pta, rrl, rrs, hsp65, rpoB, 16S-23S rRNA ITS, recF, lipT, pepB, gnd, aspB, groEL, sodA and est) previously used for genotyping of MAC and other NTM. Seven genes (fusA, secA, rpoB, hsp65, 16S rRNA, 23S rRNA, 16S-23S rRNA ITS) had a discriminatory power index higher than 0.9 and were included in the optimized set that we used. This set was significantly better for genotyping and diagnosis of MAC than previously used 4-gene, 5-gene and 9-gene sets. MLST using our 7-gene set indicated that the rate of reinfection was 54.55% (6/11 cases). Persistent infections (n = 5 cases, 45.45%) were found. A changing of clone in the same patient was found in 1/4 (25%) of the colonization cases. Two small clusters of possible MAC transmission between humans were found. Our study demonstrated that the high frequency of apparent treatment failure of MAC might be artefactual, as a consequence of a high rate of MAC reinfection in Thai population. Our useful highly discriminative gene set for MAC species and clonal strain analysis could be further applied for the diagnosis and patient management.

Population Genomics and Inference of Mycobacterium avium Complex Clusters in Cystic Fibrosis Care Centers, United States.

Mycobacterium avium complex (MAC) species constitute most mycobacteria infections in persons with cystic fibrosis (CF) in the United States, but little is known about their genomic diversity or transmission. During 2016–2020, we performed whole-genome sequencing on 364 MAC isolates from 186 persons with CF from 42 cystic fibrosis care centers (CFCCs) across 23 states. We compared isolate genomes to identify instances of shared strains between persons with CF. Among persons with multiple isolates sequenced, 15/56 (27%) had >1 MAC strain type. Genomic comparisons revealed 18 clusters of highly similar isolates; 8 of these clusters had patients who shared CFCCs, which included 27/186 (15%) persons with CF. We provide genomic evidence of highly similar MAC strains shared among patients at the same CFCCs. Polyclonal infections and high genetic similarity between MAC isolates are consistent with multiple modes of acquisition for persons with CF to acquire MAC infections.

1388. Epidemiology and Treatment Outcomes of Nontuberculous Mycobacterial Infections at a Community Teaching Hospital in the Southeastern United States

BackgroundGaps in evidence concerning the epidemiology of nontuberculous mycobacterial (NTM) organisms and their associated treatment outcomes are evident in the literature. The aim of this study was to describe NTM species distribution and susceptibility profile and associated treatment outcomes among adult patients at a tertiary referral hospital in the Southeastern United States.MethodsA retrospective cohort study of adult patients with NTM infections from January 1, 2010 to June 30, 2020 was performed. Included patients had a positive culture for NTM species and clinical suspicion of infection. Patients were excluded if they had concurrent positive culture for M. tuberculosis (MTB) or monomicrobial culture for M. gordonae. Study endpoints included predictors for favorable treatment outcome, species distribution, and susceptibility at baseline. Favorable treatment outcome was defined as physician-guided cessation of therapy due to clinical improvement. Univariate followed by multivariate regression analysis was used to analyze favorable predictors. ResultsA total of 250 and 78 patients were included in microbiologic and outcomes cohorts, respectively. Among treated patients, 47 (60%) had a favorable treatment outcome. The outcomes cohort consisted primarily of non-Hispanic Caucasians (71%) with pulmonary infection (67%). The most common isolates observed were Mycobacterium avium complex (MAC) (67%) and M. abscessus (18%). Being self-pay, underweight, history of MTB treatment, and concurrent asthma were more common in those with unfavorable treatment outcomes. The significant favorable predictors included antibiotic change not due to escalation or de-escalation of therapy and private insurance. Among MAC isolates, clarithromycin and amikacin were highly susceptible; however, M. abscessus has reduced susceptibility to first-line agents such as amikacin, clarithromycin, and cefoxitin (Table 1). Table 1. Baseline Susceptibility ConclusionConsidering the long incubation time, knowledge of prevalence, antimicrobial susceptibility patterns, and outcomes could guide empirical antimicrobial selection for NTM infections. This is particularly useful for M. abscessus infections where most isolates carry significant resistance to one or more first-line agents. Disclosures Julie Ann Justo, PharmD, MS, BCPS-AQ ID, bioMerieux (Speaker’s Bureau)Merck & Co. (Advisor or Review Panel member)Therapeutic Research Center (Speaker’s Bureau)Vaxart (Shareholder) P. Brandon Bookstaver, Pharm D, ALK Abello, Inc. (Grant/Research Support, Advisor or Review Panel member)Biomerieux (Speaker’s Bureau)Kedrion Biopharma (Grant/Research Support, Advisor or Review Panel member)

Difference in drug susceptibility distribution and clinical characteristics between Mycobacterium avium and Mycobacterium intracellulare lung diseases in Shanghai, China.

Introduction. Mycobacterium avium complex (MAC) has been reported as the most common aetiology of lung disease involving nontuberculous mycobacteria.Hypothesis. Antimicrobial susceptibility and clinical characteristics may differ between Mycobacterium avium and Mycobacterium intracellulare.Aim. We aimed to evaluate the differences in antimicrobial susceptibility profiles between two major MAC species (Mycobacterium avium and Mycobacterium intracellulare) from patients with pulmonary infections and to provide epidemiologic data with minimum inhibitory concentration (MIC) distributions.Methodology. Between January 2019 and May 2020, 45 M. avium and 242 M. intracellulare isolates were obtained from Shanghai Pulmonary Hospital. The demographic and clinical characteristics of patients were obtained from their medical records. The MICs of 13 antimicrobials were determined for the MAC isolates using commercial Sensititre SLOWMYCO MIC plates and the broth microdilution method, as recommended by the Clinical and Laboratory Standards Institute (CLSI; Standards M24-A2). MIC50 and MIC90 values were derived from the MIC distributions.Results. M. intracellulare had higher resistance rates than M. avium for most tested antimicrobials except clarithromycin, ethambutol, and ciprofloxacin. Clarithromycin was the most effective antimicrobial against both the M. avium (88.89 %) and M. intracellulare (91.32 %) isolates, with no significant difference between the species (P=0.601). The MIC90 of clarithromycin was higher for M. avium (32 µg ml-1) than M. intracellulare (8 µg ml-1). The MIC50 of rifabutin was more than four times higher for M. intracellulare (1 µg ml-1) than M. avium (≤0.25 µg ml-1). The percentages of patients aged >60 years and patients with sputum, cough, and cavitary lesions were significantly higher than among patients with M. intracellulare infection than M. avium infections.Conclusions. The pulmonary disease caused by distinct MAC species had different antimicrobial susceptibility, symptoms, and radiographic findings.

Association between 16S rRNA gene mutations and susceptibility to amikacin in Mycobacterium avium Complex and Mycobacterium abscessus clinical isolates

We evaluated the association between 16S rRNA gene (rrs) mutations and susceptibility in clinical isolates of amikacin-resistant nontuberculous mycobacteria (NTM) in NTM-pulmonary disease (PD) patients. Susceptibility was retested for 134 amikacin-resistant isolates (minimum inhibitory concentration [MIC] ≥ 64 µg/ml) from 86 patients. Amikacin resistance was reconfirmed in 102 NTM isolates from 62 patients with either Mycobacterium avium complex-PD (MAC-PD) (n = 54) or M. abscessus-PD (n = 8). MICs and rrs mutations were evaluated for 318 single colonies from these isolates. For the 54 MAC-PD patients, rrs mutations were present in 34 isolates (63%), comprising all 31 isolates with amikacin MICs ≥ 128 µg/ml, but only three of 23 isolates with an MIC = 64 µg/ml. For the eight M. abscessus-PD patients, all amikacin-resistant (MIC ≥ 64 µg/ml) isolates had rrs mutations. In amikacin-resistant isolates, the A1408G mutation (n = 29) was most common. Two novel mutations, C1496T and T1498A, were also identified. The culture conversion rate did not differ by amikacin MIC. Overall, all high-level and 13% (3/23) of low-level amikacin-resistant MAC isolates had rrs mutations whereas mutations were present in all amikacin-resistant M. abscessus isolates. These findings are valuable for managing MAC- and M. abscessus-PD and suggest the importance of phenotypic and genotypic susceptibility testing.

877. Use of Statistical Process Control Charts for Early Detection of Healthcare Facility-Associated Nontuberculous Mycobacterial Outbreaks

BackgroundNontuberculous mycobacteria (NTM) are increasingly implicated in healthcare facility-associated (HCFA) outbreaks. However, systematic methods for NTM surveillance and outbreak detection are lacking and represent an emerging need. We examined how statistical process control (SPC) might perform in NTM outbreak detection.MethodsSPC charts were optimized for surgical site infection surveillance and adapted to analyze 3 NTM outbreaks that occurred from 2013-2016 at a single hospital. The first 2 outbreaks occurred contemporaneously and consisted of pulmonary Mycobacterium abscessus complex (MABC) acquisition and cardiac surgery-associated extrapulmonary MABC infection, respectively. The third outbreak was a pseudo-outbreak of Mycobacterium avium complex (MAC) at a bronchoscopy suite.We retrospectively analyzed monthly rates of unique patients who had: 1) positive respiratory cultures for MABC obtained on hospital day 3 or later; 2) positive non-respiratory cultures for MABC; and 3) positive bronchoalveolar lavage (BAL) cultures for MAC collected at the bronchoscopy suite. For each outbreak, we used these rates to construct a standardized moving average (MA) SPC chart with MA span of 3 months. Rolling baselines were estimated from average rates for months 7 through 12 prior to each monthly data point. SPC detection was indicated by the first data point above the upper control limit (UCL) of 3 standard deviations. Traditional surveillance detection was defined as the time of outbreak detection by routine infection control procedures.ResultsSPC detection occurred 5, 4, and 9 months prior to traditional surveillance outbreak detection for the three outbreaks, respectively (Figures 1 and 2). Prospective NTM surveillance using the MA chart potentially would have prevented an estimated 19 cases of pulmonary MABC, 9 cases of extrapulmonary MABC, and 80 cases of BAL MAC isolation (Table). No data points exceeded the UCL during 95 cumulative months of post-outbreak surveillance, suggesting low burden of false positive SPC signals.Figure 1. Use of a moving average statistical process control (SPC) chart for early detection of hospital-associated outbreaks of pulmonary Mycobacterium abscessus complex (MABC) and cardiac surgery-associated extrapulmonary MABC infection. The pulmonary chart analyzes cases of hospital-onset respiratory isolation of MABC. The extrapulmonary chart analyzes cases of positive non-respiratory cultures for MABC. CL, center line; LCL, lower control limit; UCL, upper control limit. Figure 2. Use of a moving average statistical process control (SPC) chart for early detection of a pseudo-outbreak of Mycobacterium avium complex (MAC) that occurred at a bronchoscopy suite. The chart analyzes cases of MAC isolated from bronchoalveolar lavage cultures. CL, center line; LCL, lower control limit; UCL, upper control limit. Table. Estimated cases of hospital-associated nontuberculous mycobacteria that would have been prevented by prospective surveillance with a moving average statistical process control (SPC) chart. ConclusionA single MA SPC chart detected 3 HCFA NTM outbreaks an average of 6 months earlier than traditional surveillance. SPC has potential to improve NTM surveillance, promoting early cluster detection and prevention of HCFA NTM.Disclosures All Authors: No reported disclosures

Prevalence, awareness of butchers and Antimicrobial Pattern of Mycobacterium avium complex in horses at Ebonyi State, Nigeria, 2018

Background: INTRODUCTION: Atypical mycobacteria are ubiquitous with more than 140 mycobacteria species. Mycobacterium avium complex (MAC) is zoonotic in animals including, deer, horses, pigs and birds. It affects immunosuppressed human patients with acquired immunodeficiency syndrome (AIDS). Some parents/caregivers use raw horse blood as treatment for cough and Tuberculosis in Ebonyi State. MAC is not killed by any standard antituberculous drug except Ethambutol at concentrations achievable in plasma of patient Methods and materials: METHOD The sample size was 425 using prevalence of (50%) and non-response rate (10%). Collection of specimens was by physical examination of organs. Thirty-five tissue with granulomatous lesions were collected at post mortem. Samples preserved, taken to TB Lab and processed for 8 weeks. Five isolates were positive to AFB test but negative to MPT64 antigen on SD-bioline. These were considered non tuberculous mycobacteria (NTM) Questionnaire on knowledge, attitude and practice were administered to 200 butchers on MAC risk. Results: MAC prevalence of 1.2% was found. The knowledge of MAC among butchers was poor. Attitude and practice of butchers toward MAC risk were poor. Mono-drug resistance against Isoniazid was in one isolate (20.0%), and multi-drug resistance against Streptomycin and Rifampicin was in one isolate (20.0%) in the horses. Conclusion: The prevalence of MAC in the horses slaughtered at Ebonyi State was low and multi drug resistant MAC isolates were in horse tissues at Ebonyi State. The knowledge of MAC among butchers was poor. Attitude and practice of butchers toward MAC risk were poor. Some isolates showed resistance to antimicrobials.

Underutilization of nontuberculous mycobacterial drug susceptibility testing in Ontario, Canada, 2010-2015.

Drug susceptibility testing (DST) in nontuberculous mycobacterial pulmonary disease (NTM-PD) is useful for some Mycobacterium species. International guidelines recommend routine use of DST for clinically relevant mycobacteria. DST use and results are poorly studied at the population level. We sought to identify the frequency of DST utilization for nontuberculous mycobacteria (NTMs) and describe the potential relevance of these results in Ontario. Using public health laboratory data, we performed a population-based retrospective analysis of NTM DST utilization in Ontario from May 2010 to June 2015. We determined the proportion of incident NTM-PD infections for which DST was performed and analyzed minimum inhibitory concentration (MIC) distributions from NTM testing overall, using thresholds recommended by the Clinical and Laboratory Standards Institute. The proportion of incident cases of NTM-PD tested for DST was 6.3% (240/3,806) for Mycobacterium avium complex (MAC), 36.2% (67/185) for M. abscessus, and 1.8% (19/1,057) for M. xenopi. Among specimens from all body sites, MAC resistance to clarithromycin occurred in 8.0% of specimens (21/262) and MAC resistance to amikacin (intravenous, MIC > 64 µg/mL) occurred in 22.6% (19/84). M.abscessus resistance occurred as follows: to amikacin, 3.8% (3/79); cefoxitin, 14.0% (11/79); imipenem, 30.4% (14/46); linezolid, 39.2% (31/79); clarithromycin, 54.2% (13/24); ciprofloxacin, 92.4% (73/79); and moxifloxacin, 91.1% (51/56). M. xenopi analysis was limited by few DST requests and a lack of DST clinical correlation. We found that NTM DST is underutilized in Ontario and observed a very high frequency of amikacin resistance among MAC isolates.

Rational Choice of Antibiotics and Media for Mycobacterium avium Complex Drug Susceptibility Testing.

The Clinical and Laboratory Standards Institute recommends the use of Mueller Hinton (MH) medium to perform drug susceptibility testing (DST) of Mycobacterium avium complex (MAC) using the microdilution method. For MAC, there has been no study on the impact of media on the determination of minimum inhibitory concentrations (MICs) of antibiotics other than clarithromycin. This study aimed at determining the impact of two media used for DST of MAC and at augmenting the number of pertinent MICs for MAC species encountered in clinical practice. MICs of antibiotics used for the treatment of MAC infections were determined for 158 clinical MAC isolates (80 M. avium, 40 M. intracellulare, 35 M. chimaera, two M. yongonense and one M. timonense) in MH and 7H9 broths using the SLOMYCO SensititreTM system (TREK Diagnostic Systems, East Grinstead, United Kingdom). The modal MICs determined in both media were the same for linezolid, moxifloxacin, rifabutin and amikacin but not for clarithromycin, rifampin and ethambutol. The kappa test for MICs converted to susceptibility categories showed an excellent agreement for clarithromycin, a moderate agreement for linezolid and a weak agreement for moxifloxacin and amikacin. For amikacin, 7H9 allowed a better distinction (fewer intermediate strains) of wild-type populations than MH. Existing breakpoints for linezolid and moxifloxacin are spread through the distribution of MICs for wild-type populations. The only breakpoints that can be used rationally are those for amikacin and clarithromycin. For amikacin, 7H9 performs better than MH, whereas both media perform equally for clarithromycin. Given that testing in 7H9, as opposed to MH, allows easier MIC measurements and yields greater reproducibility, we propose the use of 7H9 medium for DST of MAC.

MAC Attack: Clinical Correlates of Mycobacterium avium Complex Infection Among Patients With and Without Cancer.

BackgroundIn 2007 the American Thoracic Society (ATS) released guidelines on management of Mycobacterium avium complex (MAC), an increasingly common respiratory organism worldwide. Determining when this represents a true respiratory pathogen remains controversial and becomes increasingly challenging in patients with cancer. This study aims to 1) describe the phenotype that exists among cancer patients with MAC colonization and MAC pulmonary infection when compared to non-cancer patients; 2) assess whether cancer, symptoms, and radiographs, were associated with the decision to treat MAC pulmonary infection with antibiotics.MethodsWe retrospectively analyzed 550 adult, non-human immunodeficiency virus (HIV) patients, among whom MAC was identified in respiratory cultures or tissue. Radiographs, clinical symptoms and cancer status were studied. Patients were categorized as having MAC pulmonary infection based on 2007 ATS guidelines, and antibiotic treatment was thereafter reviewed. Fisher’s exact test and Wilcoxon Rank sum assessed differences.ResultsMedian age of the 550 patients was 68 years; most were female (56%) and white (83%). Symptoms and radiographic abnormalities accompanying MAC isolation were common, occurring among 83% and 99.6% respectively of all patients. There were 444 patients with MAC who had current or inactive cancers, most commonly hematologic (30%) and lung (25%) malignancies, while 106 patients never had cancer. Cancer patients were younger (P = 0.028), less often female (P < 0.001), and had less-frequent pre-existing lung disease (P = 0.017) than those without cancer. There were 196 (35%) patients determined to have MAC pulmonary infection, among whom 49 (9%) received directed antibiotics. Those receiving antibiotics had lower body mass index (BMI) (P < 0.0001), more frequent pre-existing lung disease (P = 0.003) and lower cancer rates (P = 0.008) than those not receiving antibiotics. Patients receiving antibiotics were more likely to have cavitary disease (P = 0.001), cough/dyspnea (P = 0.012), hemoptysis (P < 0.001), and constitutional symptoms (P = 0.001).ConclusionsIn concordance with ATS guidelines, hemoptysis, constitutional symptoms, cough/dyspnea and cavitary disease were associated with highest likelihood to treat with antibiotics. The phenotype in cancer patients was quite different than the classic Lady Windermere syndrome. MAC pulmonary infection was treated less often in cancer patients. This study extends beyond the ATS guidelines to examine the potential import of malignancy on the colonization and potential treatment of MAC.

1386. Reduction in Expected Survival Associated with Nontuberculous Mycobacterial Pulmonary Infection

BackgroundNontuberculous mycobacteria (NTM) are emerging agents of pulmonary disease, estimated to affect >80,000 people in the United States. While the spectrum of pulmonary NTM severity is broad, some published series report 5-year mortality of up to 40%.MethodsWe conducted a retrospective cohort study to examine mortality of patients with positive respiratory cultures for NTM in the Duke Health System from January 1, 1996 to June 30, 2015, compared with the expected mortality in the US population among a cohort with the same demographic composition. We included patients with ≥2 positive NTM respiratory cultures, or 1 positive culture plus an associated ICD diagnosis. Patients with disseminated NTM, HIV, cystic fibrosis, and solid-organ or hematopoietic cell transplants were excluded, as were isolates of Mycobacterium gordonae. Five specific comorbidities (cancer, chronic obstructive pulmonary disease, stroke, chronic renal failure, myocardial infarction) were assessed with ICD codes. Survival was measured from the date of first positive NTM culture and censored as of 6/30/2015.ResultsWe identified 653 patients who met the case definition. 451 (69%) were female; 548 (84%) were Caucasian, and the median age was 69 years (IQR 59–76). 544 (83.3%) patients had only Mycobacterium avium complex (MAC) isolates in cultures; 39 (6%) had only M. abscessus; 33 (5%) had both MAC and M. abscessus; 37 (5.7%) had other NTM isolates. Most patients (n = 410, 62.8%) had none of the evaluated comorbidities prior to NTM diagnosis. Median follow-up time was 1252 days (IQR 449–2688). Median survival in our cohort among persons with and without comorbidities was 1973 days (95% CI 1487–2995) and 3952 days (95% CI 3496–5186), respectively. Median expected survival in the demographically-matched population cohort was significantly longer at 5479 days (P<.0001). Mortality at 5 years was 47.9% (39.7–55.0) and 27.2% (95% CI 22.1–32.0) among NTM patients with and without comorbidities, respectively, vs. expected mortality of 5.7% in the general population.ConclusionNTM pulmonary infection in our cohort was associated with significantly lower survival than expected in the general population. The impact of NTM infection itself vs. other comorbidities on survival requires further study. Disclosures All authors: No reported disclosures.