ABSTRACT
Whole-genome sequencing (WGS) has recently been used to investigate acquisition of Mycobacterium abscessus. Investigators have reached conflicting conclusions about the meaning of genetic distances for interpretation of person-to-person transmission. Existing genomic studies were limited by a lack of WGS from environmental M. abscessus isolates. In this study, we retrospectively analyzed the core and accessory genomes of 26 M. abscessus subsp. abscessus isolates collected over 7 years. Clinical isolates (n = 22) were obtained from a large hospital-associated outbreak of M. abscessus subsp. abscessus, the outbreak hospital before or after the outbreak, a neighboring hospital, and two outside laboratories. Environmental M. abscessus subsp. abscessus isolates (n = 4) were obtained from outbreak hospital water outlets. Phylogenomic analysis of study isolates revealed three clades with pairwise genetic distances ranging from 0 to 135 single-nucleotide polymorphisms (SNPs). Compared to a reference environmental outbreak isolate, all seven clinical outbreak isolates and the remaining three environmental isolates had highly similar core and accessory genomes, differing by up to 7 SNPs and a median of 1.6% accessory genes, respectively. Although genomic comparisons of 15 nonoutbreak clinical isolates revealed greater heterogeneity, five (33%) isolates had fewer than 20 SNPs compared to the reference environmental isolate, including two unrelated outside laboratory isolates with less than 4% accessory genome variation. Detailed genomic comparisons confirmed environmental acquisition of outbreak isolates of M. abscessus subsp. abscessus. SNP distances alone, however, did not clearly differentiate the mechanism of acquisition of outbreak versus nonoutbreak isolates. We conclude that successful investigation of M. abscessus subsp. abscessus clusters requires molecular and epidemiologic components, ideally complemented by environmental sampling.
Subject(s)
Cross Infection , Disease Outbreaks , Mycobacterium Infections, Nontuberculous , Mycobacterium abscessus , Cross Infection/epidemiology , Cross Infection/microbiology , Cross Infection/transmission , Genomics , Hospitals , Humans , Mycobacterium Infections, Nontuberculous/epidemiology , Mycobacterium Infections, Nontuberculous/microbiology , Mycobacterium Infections, Nontuberculous/transmission , Mycobacterium abscessus/genetics , Retrospective StudiesABSTRACT
We characterize three respiratory isolates of the recently described species Mycobacterium talmoniae recovered in Texas, Louisiana, and Massachusetts, including the first case of disease in a patient with underlying cystic fibrosis. The three isolates had a 100% match to M. talmoniae NE-TNMC-100812T by complete 16S rRNA, rpoB region V, and hsp65 gene sequencing. Core genomic comparisons between one isolate and the type strain revealed an average nucleotide identity of 99.8%. The isolates were susceptible to clarithromycin, amikacin, and rifabutin, while resistance was observed for tetracyclines, ciprofloxacin, and linezolid. M. talmoniae should be added to the list of potential pulmonary pathogens, including in the setting of cystic fibrosis.
Subject(s)
Bronchiectasis/complications , Cystic Fibrosis/complications , Lung Diseases, Fungal/diagnosis , Mycobacterium Infections/diagnosis , Mycobacterium/classification , Mycobacterium/isolation & purification , Phylogeny , Aged , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Chaperonin 60/genetics , Child , Cluster Analysis , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , DNA-Directed RNA Polymerases/genetics , Female , Humans , Louisiana , Lung Diseases, Fungal/microbiology , Male , Massachusetts , Microbial Sensitivity Tests , Mycobacterium/drug effects , Mycobacterium/genetics , Mycobacterium Infections/microbiology , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , TexasABSTRACT
The accuracy and robustness of the Vitek MS v3.0 matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) system was evaluated by identifying mycobacteria from automated liquid-medium systems using patient samples. This is the first report to demonstrate that proteins within the liquid medium, its supplements, and decontamination reagents for nonsterile patient samples do not generate misidentification or false-positive results by use of the Vitek MS v3.0 system. Prior to testing with patient samples, a seeded-culture study was conducted to challenge the accuracy of the Vitek MS system at identifying mycobacteria from liquid medium by mimicking a clinical workflow. Seventy-seven Mycobacterium strains representing 21 species, seeded in simulated sputum, were decontaminated, inoculated into BacT/Alert MP liquid culture medium, incubated until positivity, and identified using the Vitek MS system. A total of 383 liquid cultures were tested, of which 379 (99%) were identified correctly to the species/complex/group level, 4 (1%) gave a "no-identification" result, and no misidentifications were observed. Following the simulated-sputum study, a total of 73 smear-positive liquid-medium cultures detected using BD BBL MGIT and VersaTREK Myco liquid media were identified by the Vitek MS system. Sixty-four cultures (87.7%) were correctly identified to the species/complex/group level; 7 (9.6%) resulted in no identification; and 2 (2.7%) were misidentified at the species level. These results indicate that the Vitek MS v3.0 system is an accurate tool for routine diagnostics of Mycobacterium species isolated from liquid cultures.
Subject(s)
Bacteriological Techniques/methods , Mycobacterium Infections, Nontuberculous/diagnosis , Mycobacterium/classification , Mycobacterium/isolation & purification , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Bacteriological Techniques/instrumentation , Culture Media , Diagnostic Tests, Routine , Humans , Mycobacterium/chemistry , Sputum/microbiologyABSTRACT
This multicenter study was designed to assess the accuracy and reproducibility of the Vitek MS v3.0 matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry system for identification of Mycobacterium and Nocardia species compared to DNA sequencing. A total of 963 clinical isolates representing 51 taxa were evaluated. In all, 663 isolates were correctly identified to the species level (69%), with another 231 (24%) correctly identified to the complex or group level. Fifty-five isolates (6%) could not be identified despite repeat testing. All of the tuberculous mycobacteria (45/45; 100%) and most of the nontuberculous mycobacteria (569/606; 94%) were correctly identified at least to the group or complex level. However, not all species or subspecies within the M. tuberculosis, M. abscessus, and M. avium complexes and within the M. fortuitum and M. mucogenicum groups could be differentiated. Among the 312 Nocardia isolates tested, 236 (76%) were correctly identified to the species level, with an additional 44 (14%) correctly identified to the complex level. Species within the N. nova and N. transvalensis complexes could not always be differentiated. Eleven percent of the isolates (103/963) underwent repeat testing in order to get a final result. Identification of a representative set of Mycobacterium and Nocardia species was highly reproducible, with 297 of 300 (99%) replicates correctly identified using multiple kit lots, instruments, analysts, and sites. These findings demonstrate that the system is robust and has utility for the routine identification of mycobacteria and Nocardia in clinical practice.
Subject(s)
Mycobacterium tuberculosis/isolation & purification , Nocardia/isolation & purification , Nontuberculous Mycobacteria/isolation & purification , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/instrumentation , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , High-Throughput Nucleotide Sequencing , Humans , Mycobacterium tuberculosis/genetics , Nocardia/genetics , Nocardia Infections/diagnosis , Nocardia Infections/microbiology , RNA, Ribosomal, 16S/genetics , Reagent Kits, Diagnostic , Reproducibility of Results , Tuberculosis/diagnosis , Tuberculosis/microbiologyABSTRACT
BACKGROUND: Nontuberculous mycobacteria (NTM) commonly colonize municipal water supplies and cause healthcare-associated outbreaks. We investigated a biphasic outbreak of Mycobacterium abscessus at a tertiary care hospital. METHODS: Case patients had recent hospital exposure and laboratory-confirmed colonization or infection with M. abscessus from January 2013 through December 2015. We conducted a multidisciplinary epidemiologic, field, and laboratory investigation. RESULTS: The incidence rate of M. abscessus increased from 0.7 cases per 10000 patient-days during the baseline period (January 2013-July 2013) to 3.0 cases per 10000 patient-days during phase 1 of the outbreak (August 2013-May 2014) (incidence rate ratio, 4.6 [95% confidence interval, 2.3-8.8]; P < .001). Thirty-six of 71 (51%) phase 1 cases were lung transplant patients with positive respiratory cultures. We eliminated tap water exposure to the aerodigestive tract among high-risk patients, and the incidence rate decreased to baseline. Twelve of 24 (50%) phase 2 (December 2014-June 2015) cases occurred in cardiac surgery patients with invasive infections. Phase 2 resolved after we implemented an intensified disinfection protocol and used sterile water for heater-cooler units of cardiopulmonary bypass machines. Molecular fingerprinting of clinical isolates identified 2 clonal strains of M. abscessus; 1 clone was isolated from water sources at a new hospital addition. We made several water engineering interventions to improve water flow and increase disinfectant levels. CONCLUSIONS: We investigated and mitigated a 2-phase clonal outbreak of M. abscessus linked to hospital tap water. Healthcare facilities with endemic NTM should consider similar tap water avoidance and engineering strategies to decrease risk of NTM infection.
Subject(s)
Cross Infection , Disease Outbreaks , Mycobacterium Infections, Nontuberculous/epidemiology , Mycobacterium Infections, Nontuberculous/microbiology , Mycobacterium abscessus/classification , Mycobacterium abscessus/genetics , Aged , Female , Genes, Bacterial , Hospitals , Humans , Incidence , Male , Middle Aged , Multilocus Sequence Typing , Mycobacterium Infections, Nontuberculous/diagnosis , Mycobacterium Infections, Nontuberculous/etiology , Risk FactorsABSTRACT
Bedaquiline (BDQ), a diarylquinoline antibiotic that targets ATP synthase, is effective for the treatment of Mycobacterium tuberculosis infections that no longer respond to conventional drugs. While investigating the off-label use of BDQ as salvage therapy, seven of 13 patients with Mycobacterium intracellulare lung disease had an initial microbiological response and then relapsed. Whole-genome comparison of pretreatment and relapse isolates of M. intracellulare uncovered mutations in a previously uncharacterized locus, mmpT5 Preliminary analysis suggested similarities between mmpT5 and the mmpR5 locus, which is associated with low-level BDQ resistance in M. tuberculosis Both genes encode transcriptional regulators and are adjacent to orthologs of the mmpS5-mmpL5 drug efflux operon. However, MmpT5 belongs to the TetR superfamily, whereas MmpR5 is a MarR family protein. Targeted sequencing uncovered nonsynonymous mmpT5 mutations in isolates from all seven relapse cases, including two pretreatment isolates. In contrast, only two relapse patient isolates had nonsynonymous changes in ATP synthase subunit c (atpE), the primary target of BDQ. Susceptibility testing indicated that mmpT5 mutations are associated with modest 2- to 8-fold increases in MICs for BDQ and clofazimine, whereas one atpE mutant exhibited a 50-fold increase in MIC for BDQ. Bedaquiline shows potential for the treatment of M. intracellulare lung disease, but optimization of treatment regimens is required to prevent the emergence of mmpT5 variants and microbiological relapse.
Subject(s)
Antitubercular Agents/therapeutic use , Diarylquinolines/therapeutic use , Drug Resistance, Bacterial , Mutation, Missense , Mycobacterium avium Complex/genetics , Transcription Factors/genetics , Tuberculosis, Pulmonary/drug therapy , Aged , Female , Genome, Bacterial , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Mycobacterium avium Complex/isolation & purification , Recurrence , Sequence Analysis, DNA , Tuberculosis, Pulmonary/microbiologyABSTRACT
A previously undescribed, rapidly growing, scotochromogenic species of the genus Mycobacterium (represented by strains PB739T and GK) was isolated from two clinical sources - the sputum of a 76-year-old patient with severe chronic obstructive pulmonary disease, history of tuberculosis exposure and Mycobacterium avium complex isolated years prior; and the blood of a 15-year-old male with B-cell acute lymphoblastic leukaemia status post bone marrow transplant. The isolates grew as dark orange colonies at 25-37 °C after 5 days, sharing features in common with other closely related species. Analysis of the complete 16S rRNA gene sequence (1492 bp) of strain PB739T demonstrated that the isolate shared 98.8â% relatedness with Mycobacterium wolinskyi. Partial 429 bp hsp65 and 744 bp rpoB region V sequence analyses revealed that the sequences of the novel isolate shared 94.8 and 92.1â% similarity with those of Mycobacterium neoaurum and Mycobacterium aurum, respectively. Biochemical profiling, antimicrobial susceptibility testing, HPLC/gas-liquid chromatography analyses and multilocus sequence typing support the taxonomic status of these isolates (PB739T and GK) as representatives of a novel species. Both isolates were susceptible to the Clinical and Laboratory Standards Institute recommended antimicrobials for susceptibility testing of rapidly growing mycobacteria including amikacin, ciprofloxacin, moxifloxacin, doxycycline/minocycline, imipenem, linezolid, clarithromycin and trimethropin/sulfamethoxazole. Both isolates PB739T and GK showed intermediate susceptibility to cefoxitin. We propose the name Mycobacterium grossiae sp. nov. for this novel species and have deposited the type strain in the DSMZ and CIP culture collections. The type strain is PB739T (=DSM 104744T=CIP 111318T).
Subject(s)
Mycobacterium Infections/microbiology , Mycobacterium/classification , Phylogeny , Adolescent , Aged , Bacterial Typing Techniques , Blood Culture , DNA, Bacterial/genetics , Humans , Male , Multilocus Sequence Typing , Mycobacterium/genetics , Mycobacterium/isolation & purification , Mycobacterium Infections/blood , Pigmentation , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Sputum/microbiologyABSTRACT
We compared the activities of the carbapenems ertapenem, meropenem, and imipenem against 180 isolates of rapidly growing mycobacteria (RGM) and 170 isolates of Nocardia using the Clinical and Laboratory Standards Institute (CLSI) guidelines. A subset of isolates was tested using the Etest. The rate of susceptibility to ertapenem and meropenem was limited and less than that to imipenem for the RGM. Analysis of major and minor discrepancies revealed that >90% of the isolates of Nocardia had higher MICs by the broth microdilution method than by Etest, in contrast to the lower broth microdilution MICs seen for >80% of the RGM. Imipenem remains the most active carbapenem against RGM, including Mycobacterium abscessus subsp. abscessus For Nocardia, imipenem was significantly more active only against Nocardia farcinica Although there may be utility in testing the activities of the newer carbapenems against Nocardia, their activities against the RGM should not be routinely tested. Testing by Etest is not recommended by the CLSI.
Subject(s)
Anti-Bacterial Agents/pharmacology , Imipenem/pharmacology , Microbial Sensitivity Tests/methods , Nocardia/drug effects , Nontuberculous Mycobacteria/drug effects , Thienamycins/pharmacology , beta-Lactams/pharmacology , Ertapenem , Humans , Meropenem , Nocardia/isolation & purification , Nontuberculous Mycobacteria/isolation & purificationABSTRACT
Mycobacterium terrae complex has been recognized as a cause of tenosynovitis, with M. terrae and Mycobacterium nonchromogenicum reported as the primary etiologic pathogens. The molecular taxonomy of the M. terrae complex causing tenosynovitis has not been established despite approximately 50 previously reported cases. We evaluated 26 isolates of the M. terrae complex associated with tenosynovitis or osteomyelitis recovered between 1984 and 2014 from 13 states, including 5 isolates reported in 1991 as M. nonchromogenicum by nonmolecular methods. The isolates belonged to three validated species, one new proposed species, and two novel related strains. The majority of isolates (20/26, or 77%) belonged to two recently described species: Mycobacterium arupense (10 isolates, or 38%) and Mycobacterium heraklionense (10 isolates, or 38%). Three isolates (12%) had 100% sequence identity to each other by 16S rRNA and 99.3 to 100% identity by rpoB gene region V sequencing and represent a previously undescribed species within the M. terrae complex. There were no isolates of M. terrae or M. nonchromogenicum, including among the five isolates reported in 1991. The 26 isolates were susceptible to clarithromycin (100%), rifabutin (100%), ethambutol (92%), and sulfamethoxazole or trimethoprim-sulfamethoxazole (70%). The current study suggests that M. arupense, M. heraklionense, and a newly proposed species ("M. virginiense" sp. nov.; proposed type strain MO-233 [DSM 100883, CIP 110918]) within the M. terrae complex are the major causes of tenosynovitis and osteomyelitis in the United States, with little change over 20 years. Species identification within this complex requires sequencing methods.
Subject(s)
Mycobacterium Infections, Nontuberculous/microbiology , Mycobacterium/classification , Mycobacterium/isolation & purification , Osteomyelitis/microbiology , Tenosynovitis/microbiology , Adult , Aged , Antitubercular Agents/pharmacology , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , DNA-Directed RNA Polymerases , Female , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Mycobacterium/drug effects , Mycobacterium/genetics , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , United States , Young AdultABSTRACT
The taxonomic position of members of the Mycobacterium abscessus complex has been the subject of intensive investigation and, in some aspects confusion, in recent years as a result of varying approaches to genetic data interpretation. Currently, the former species Mycobacterium massiliense and Mycobacterium bolletii are grouped together as Mycobacterium abscessus subsp. bolletii. They differ greatly, however, as the former M. bolletii has a functional erm(41) gene that confers inducible resistance to macrolides, the primary therapeutic antimicrobials for M. abscessus, while in the former M. massiliense the erm(41) gene is non-functional. Furthermore, previous whole genome studies of the M. abscessus group support the separation of M. bolletii and M. massiliense. To shed further light on the population structure of Mycobacterium abscessus, 43 strains and three genomes retrieved from GenBank were subjected to pairwise comparisons using three computational approaches: verage ucleotide dentity, enome to enome istance and single nucleotide polymorphism analysis. The three methods produced overlapping results, each demonstrating three clusters of strains corresponding to the same number of taxonomic entities. The distances were insufficient to warrant distinction at the species level, but met the criteria for differentiation at the subspecies level. Based on prior erm(41)-related phenotypic data and current genomic data, we conclude that the species M. abscessus encompasses, in adjunct to the presently recognized subspecies M. abscessus subsp. abscessus and M. abscessus subsp. bolletii, a third subspecies for which we suggest the name M. abscessus subsp. massiliense comb. nov. (type strain CCUG 48898T=CIP 108297T=DSM 45103T=KCTC 19086T).
Subject(s)
Mycobacterium/classification , Phylogeny , Bacterial Proteins/genetics , Bacterial Typing Techniques , DNA, Bacterial/genetics , Humans , Mycobacterium/genetics , Sequence Analysis, DNAABSTRACT
The erm(41) gene confers inducible macrolide resistance in Mycobacterium abscessus subsp. abscessus, calling into question the usefulness of macrolides for treating M. abscessus subsp. abscessus infections. With an extended incubation (14 days), isolates with MICs of ≥8 µg/ml are considered macrolide resistant by current CLSI guidelines. Our goals were to determine the incidence of macrolide susceptibility in U.S. isolates, the validity of currently accepted MIC breakpoints, and the erm(41) sequences associated with susceptibility. Of 349 isolates (excluding those with 23S rRNA gene mutations), 85 (24%) had clarithromycin MICs of ≤8 µg/ml. Sequencing of the erm(41) genes from these isolates, as well as from isolates with MICs of ≥16 µg/ml, including ATCC 19977T, revealed 10 sequevars. The sequence in ATCC 19977T was designated sequevar (type) 1; most macrolide-resistant isolates were of this type. Seven sequevars contained isolates with MICs of >16 µg/ml. The T28C substitution in erm(41), previously associated with macrolide susceptibility, was identified in 62 isolates (18%) comprising three sequevars, with MICs of ≤2 (80%), 4 (10%), and 8 (10%) µg/ml. No other nucleotide substitution was associated with macrolide susceptibility. We recommend that clarithromycin susceptibility breakpoints for M. abscessus subsp. abscessus be changed from ≤2 to ≤4 µg/ml and that isolates with an MIC of 8 µg/ml have repeat MIC testing or erm sequencing performed. Our studies suggest that macrolides are useful for treating approximately 20% of U.S. isolates of M. abscessus subsp. abscessus. Sequencing of the erm gene of M. abscessus subsp. abscessus will predict inducible macrolide susceptibility.
Subject(s)
Anti-Bacterial Agents/pharmacology , Clarithromycin/pharmacology , Drug Resistance, Bacterial , Methyltransferases/genetics , Mycobacterium/drug effects , Mycobacterium/enzymology , Genotype , Humans , Macrolides/pharmacology , Microbial Sensitivity Tests , Molecular Sequence Data , Mutant Proteins/genetics , Mycobacterium/genetics , Sequence Analysis, DNA , United StatesABSTRACT
Macrolide resistance has been linked to the presence of a functional erythromycin ribosomal methylase (erm) gene in most species of pathogenic rapidly growing mycobacteria (RGM). For these Mycobacterium isolates, extended incubation in clarithromycin is necessary to determine macrolide susceptibility. In contrast, the absence of a detectable erm gene in isolates of M. chelonae, M. senegalense, and M. peregrinum and a nonfunctional erm gene in M. abscessus subsp. massiliense and 15% to 20% of M. abscessus subsp. abscessus isolates renders these species intrinsically macrolide susceptible. Not all RGM species have been screened for the presence of an erm gene, including the Mycobacterium mucogenicum group (M. mucogenicum, M. phocaicum, and M. aubagnense) and Mycobacterium immunogenum. A total of 356 isolates of these two pathogenic RGM taxa from two reference laboratories (A.R.U.P. Reference Laboratories and the Mycobacteria/Nocardia Laboratory at the University of Texas Health Science Center at Tyler) underwent clarithromycin susceptibility testing with readings at 3 to 5 days and 14 days. Only 13 of the 356 isolates had resistant clarithromycin MICs at initial extended MIC readings, and repeat values on all available isolates were ≤2 µg/ml. These studies suggest that these two additional RGM groups do not harbor functional erm genes and, like M. chelonae, do not require extended clarithromycin susceptibility testing. We propose to the Clinical Laboratory and Standards Institute that isolates belonging to these above-mentioned six rapidly growing mycobacterial groups based on molecular identification with no known functional erm genes undergo only 3 to 5 days of susceptibility testing (to exclude mutational resistance).
Subject(s)
Anti-Bacterial Agents/pharmacology , Clarithromycin/pharmacology , Methyltransferases/genetics , Nontuberculous Mycobacteria/drug effects , Nontuberculous Mycobacteria/genetics , Humans , Macrolides/pharmacology , Microbial Sensitivity Tests , Mycobacterium Infections/microbiology , Nontuberculous Mycobacteria/isolation & purification , Retrospective Studies , Time FactorsABSTRACT
Mycobacterium canariasense is a recently described late-pigmenting, rapidly growing mycobacterium linked to bacteremia in patients with underlying malignant diseases. We report a case of M. canariasense infection in a patient from Massachusetts with underlying diffuse B cell lymphoma, which was identified both by multilocus sequence typing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). To our knowledge, this is the first description after its original identification in Spain and the first report of this opportunistic pathogen in the Americas.
Subject(s)
Bacteremia/diagnosis , Catheter-Related Infections/diagnosis , Mycobacterium Infections, Nontuberculous/diagnosis , Mycobacterium/isolation & purification , Adult , Bacteremia/microbiology , Bacteremia/pathology , Catheter-Related Infections/microbiology , Catheter-Related Infections/pathology , Humans , Lymphoma, Large B-Cell, Diffuse/complications , Male , Massachusetts , Molecular Sequence Data , Multilocus Sequence Typing , Mycobacterium/chemistry , Mycobacterium/classification , Mycobacterium/genetics , Mycobacterium Infections, Nontuberculous/microbiology , Mycobacterium Infections, Nontuberculous/pathology , Spectrometry, Mass, Matrix-Assisted Laser Desorption-IonizationABSTRACT
Recent studies have shown that respiratory isolates from pulmonary disease patients and household water/biofilm isolates of Mycobacterium avium could be matched by DNA fingerprinting. To determine if this is true for Mycobacterium intracellulare, household water sources for 36 patients with Mycobacterium avium complex (MAC) lung disease were evaluated. MAC household water isolates from three published studies that included 37 additional MAC respiratory disease patients were also evaluated. Species identification was done initially using nonsequencing methods with confirmation by internal transcribed spacer (ITS) and/or partial 16S rRNA gene sequencing. M. intracellulare was identified by nonsequencing methods in 54 respiratory cultures and 41 household water/biofilm samples. By ITS sequencing, 49 (90.7%) respiratory isolates were M. intracellulare and 4 (7.4%) were Mycobacterium chimaera. In contrast, 30 (73%) household water samples were M. chimaera, 8 (20%) were other MAC X species (i.e., isolates positive with a MAC probe but negative with species-specific M. avium and M. intracellulare probes), and 3 (7%) were M. avium; none were M. intracellulare. In comparison, M. avium was recovered from 141 water/biofilm samples. These results indicate that M. intracellulare lung disease in the United States is acquired from environmental sources other than household water. Nonsequencing methods for identification of nontuberculous mycobacteria (including those of the MAC) might fail to distinguish closely related species (such as M. intracellulare and M. chimaera). This is the first report of M. chimaera recovery from household water. The study underscores the importance of taxonomy and distinguishing the many species and subspecies of the MAC.
Subject(s)
Mycobacterium avium Complex/classification , Mycobacterium avium Complex/isolation & purification , Tuberculosis, Pulmonary/microbiology , Water Microbiology , Biofilms , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , Family Characteristics , Humans , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNAABSTRACT
Recent studies have characterized a dominant clone (Clone 1) of Mycobacterium abscessus subspecies massiliense (M. massiliense) associated with high prevalence in cystic fibrosis (CF) patients, pulmonary outbreaks in the United States (US) and United Kingdom (UK), and a Brazilian epidemic of skin infections. The prevalence of Clone 1 in non-CF patients in the US and the relationship of sporadic US isolates to outbreak clones are not known. We surveyed a reference US Mycobacteria Laboratory and a US biorepository of CF-associated Mycobacteria isolates for Clone 1. We then compared genomic variation and antimicrobial resistance (AMR) mutations between sporadic non-CF, CF, and outbreak Clone 1 isolates. Among reference lab samples, 57/147 (39%) of patients with M. massiliense had Clone 1, including pulmonary and extrapulmonary infections, compared to 11/64 (17%) in the CF isolate biorepository. Core and pan genome analyses revealed that outbreak isolates had similar numbers of single nucleotide polymorphisms (SNPs) and accessory genes as sporadic US Clone 1 isolates. However, pulmonary outbreak isolates were more likely to have AMR mutations compared to sporadic isolates. Clone 1 isolates are present among non-CF and CF patients across the US, but additional studies will be needed to resolve potential routes of transmission and spread.