Mycobacterium Avium Complex Infection Research Articles

Pulmonary coccidioidomycosis complicated by nontuberculous mycobacterial pulmonary diseases with a literature review.

Following endobronchial examination, a young mine supervisor was treated with antibiotics for a pulmonary nontuberculous mycobacterial infection for approximately 1 year. However, a review of the radiological findings, which had not been previously assessed, revealed a different possibility. Accordingly, pulmonary resection was performed, enabling histopathological analysis, which showed numerous yeast-like fungi. Given the history of a stay in the southwestern United States for 2 months in 2009, 8 years previously, coccidioidomycosis was strongly suspected and the diagnosis was subsequently confirmed by serology and polymerase chain reaction testing of the excised specimen. Here, we report an educational case emphasizing the importance of meticulous medical history-taking and awareness of endemic mycoses in other countries in the context of globalization.

Treatment outcomes and relapse in patients with Mycobacterium avium-intracellulare complex pulmonary disease.

The treatment responses and outcomes in patients with Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) remain uncertain. This retrospective study was conducted in Taiwan between 2011 and 2020. A microbiological cure was defined as the requirement for a minimum of three consecutive negative cultures following culture conversion that continued until the completion of anti-MAC treatment. A total of 97 patients with MAC-PD were enrolled in this study. The sputum smear-negative conversion rate was 40% (19/47). Thirty (31%) patients achieved sputum culture-negative conversion rates within 3 years after treatment initiation. All patients with negative sputum culture conversion rates achieved microbiological cure. Patients treated with a macrolide + rifamycin + ethambutol (M + R + EMB)-based regimen had a higher microbiological cure rate than the other patients (39% vs 17%, P = 0.023). Patients with persistently positive sputum smears after 6 months of treatment had a lower microbiological cure rate than those with negative sputum smears (6% vs 44%, P < 0.001). Among 30 patients with microbiological cure, the median time from sputum culture conversion to treatment completion was 221.5 (0-483) days, and the 1-year relapse rate was 17%. Treatment with the M + R + EMB-based regimen was associated with a higher microbiological cure rate, and patients with persistently positive sputum smears after 6 months of treatment had a lower microbiological cure rate. IMPORTANCE The treatment responses and outcomes in patients with Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) remain uncertain. In this study, patients with MAC-PD treated with a macrolide + rifamycin + ethambutol (M + R + EMB)-based regimen had a higher microbiological cure rate than those treated with other regimens. After 6 months of treatment, patients with persistently positive sputum smears had a lower microbiological cure rate than those with negative sputum smears. Among patients with microbiological cure, the median time from sputum culture conversion to treatment completion was 221.5 days (range, 0-483), and the 1-year relapse rate was 17%.

Nontuberculous mycobacterial (NTM) infections in bronchiectasis patients: A retrospective US registry cohort study

RationaleLongitudinal epidemiological and clinical data are needed to improve the management of patients with bronchiectasis developing nontuberculous mycobacterial (NTM) pulmonary disease. ObjectivesTo describe the epidemiology, patient management, and treatment outcomes of NTM infections in patients with bronchiectasis enrolled in the United States Bronchiectasis and NTM Research Registry (US BRR). MethodsThis was a retrospective cohort study of patients with bronchiectasis and NTM infections enrolled with follow-up in the US BRR in 2008–2019. The study included patients with ≥1 positive NTM respiratory culture in the 24-month baseline period (baseline NTM cohort) and/or during the annual follow-up visits (incident NTM cohort). Incidence, prevalence, baseline patient characteristics, treatment exposure, treatment outcomes, and respiratory clinical outcomes were described in the baseline NTM cohort, incident NTM cohort, and both cohorts combined (prevalent NTM cohort). ResultsBetween 2008 and 2019, 37.9% (1457/3840) of patients with bronchiectasis in the US BRR met the inclusion criteria for this study and were reported to have Mycobacterium avium complex (MAC) and/or Mycobacterium abscessus complex (MABSC) infections. MAC prevalence increased steadily in the US BRR during 2009–2019; incidence was relatively stable, except for a peak in 2011 followed by a slow decrease. MABSC and mixed MAC/MABSC infections were rare. Most patients with bronchiectasis and NTM infections in the registry were female, White, and aged >65 years. The antibiotics administered most commonly reflected current guidelines. In the prevalent cohort, 44.9% of MAC infections and 37.1% of MABSC infections remained untreated during follow-up, and MAC treatment was initiated with delay (>90 days after positive NTM respiratory culture) twice as frequently as promptly (≤90 days after positive NTM respiratory culture) (68.6% vs 31.4%, respectively). The median time from diagnosis to treatment was shorter for MABSC versus MAC infections (194.0 days [interquartile range (IQR) 8.0, 380.0] vs 296.0 days [IQR 35.0, 705.0], respectively). Among patients with MAC infections who completed treatment, 27.6% were classified as cured and 29.6% as treatment failure during the annual follow-up visit window. For MABSC, these proportions were 25.0% and 28.0%, respectively. ConclusionsA considerable proportion of MAC and MABSC infections were untreated or treated after initial delay/observation. MABSC infections were more likely to be treated and start treatment sooner than MAC infections. Further longitudinal studies are warranted to evaluate the monitor-with-delay approach and inform clinical guidelines.

Dipeptidyl peptidase IV inhibitors and the risk of mycobacterial pulmonary infections in type 2 diabetes mellitus

BackgroundType 2 diabetes mellitus (DM) is a risk factor for mycobacterial pulmonary infections (MPI), including tuberculosis (TB) and nontuberculous mycobacterial lung disease (NTM-LD). Dipeptidyl peptidase IV inhibitor (DPP4i), a common DM medication, has an immune-modulation effect that raises concerns about developing MPI. However, there is scarce research on the topic. MethodsThis retrospective study was conducted in a tertiary-referral center in Taiwan from 2009 to 2016. Patients with type 2 DM who were receiving any DM medication were enrolled. TB and NTM-LD were defined by microbiological criteria. We analyzed the risk of MPI in DPP4i users using Cox proportional hazard regression with adjusted inverse probability of treatment weighting. ResultsA total of 9963 patients were included. Among them, 3931 were classified as DPP4i users, and 6032 patients were DPP4i nonusers. DPP4i users had no increase in incidences of MPI (604 vs. 768 per 100,000 person-years, p = 0.776), NTM-LD (174 vs. 255 per 100,000 person-years, p = 0.228), and TB (542 vs. 449 per 100,000 person-years, p = 0.663) relative to those of DPP4i nonusers. After adjustment, the adjusted hazard ratios for MPI (aHR: 1.07, 95% CI: 0.79–1.45), TB (aHR: 1.15, 95% CI: 0.81–1.64) and NTM-LD (aHR: 0.85, 95% CI: 0.49–1.47) were not significantly increased relative to those of nonusers. The subgroup analysis also showed that DPP4i use did not increase the risk of MPI in different DM severities and comorbidities. ConclusionsAccording to our large cohort study, DPP4i use is safe for patients with type 2 DM and might not increase the risk of MPI.

In vitro and intracellular activities of novel thiopeptide derivatives against macrolide-susceptible and macrolide-resistant Mycobacterium avium complex.

Unsatisfactory outcomes following long-term multidrug treatment in patients with Mycobacterium avium complex (MAC) pulmonary disease have urged us to develop novel antibiotics. Thiopeptides, a class of peptide antibiotics derived from natural products, have potential as drug candidates that target bacterial ribosomes, but drug development has been hampered due to their extremely poor solubility. Here, we evaluated three new compounds (AJ-037, AJ-039, and AJ-206) derived from the thiopeptide micrococcin P2 with enhanced aqueous solubility; the derivatives were generated based on structure-activity relationship analysis. We conducted in vitro drug susceptibility and intracellular antimycobacterial activity testing of the three thiopeptide derivatives against various MAC strains, including macrolide-resistant MAC clinical isolates. These compounds showed low MICs against MAC, similar to that of clarithromycin (CLR). In particular, two compounds, AJ-037 and AJ-206, had intracellular antimycobacterial activities, along with synergistic effects with CLR, and inhibited the growth of MAC inside macrophages. Moreover, these two compounds showed in vitro and intracellular anti-MAC activities against macrolide-resistant MAC strains without showing cross-resistance with CLR. Taken together, the results of the current study suggest that AJ-037 and AJ-206 can be promising anti-MAC agents for the treatment of MAC infection, including for macrolide-resistant MAC strains. IMPORTANCE Novel antibiotics for the treatment of MAC infection are urgently needed because the treatment outcomes using the standard regimen for Mycobacterium avium complex (MAC) pulmonary disease remain unsatisfactory. Here, we evaluated three novel thiopeptide derivatives (AJ-037, AJ-039, and AJ-206) derived from the thiopeptide micrococcin P2, and they were confirmed to be effective against macrolide-susceptible and macrolide-resistant MAC. Our thiopeptide derivatives have enhanced aqueous solubility through structural modifications of poorly soluble thiopeptides. The thiopeptide derivatives showed minimal inhibitory concentrations against MAC that were comparable to clarithromycin (CLR). Notably, two compounds, AJ-037 and AJ-206, exhibited intracellular antimycobacterial activities and acted synergistically with CLR to hinder the growth of MAC within macrophages. Additionally, these compounds demonstrated in vitro and intracellular anti-MAC activities against macrolide-resistant MAC strains without showing any cross-resistance with CLR. We believe that AJ-037 and AJ-206 can be promising anti-MAC agents for the treatment of MAC infections, including macrolide-resistant MAC strains.

Exploring the role of point-of-care ultrasound for people with HIV in a resource affluent setting: A prospective observational study.

In low resource settings point of care ultrasound (POCUS) has proven value for the detection of opportunistic diseases in HIV, especially tuberculosis. Few studies have explored POCUS in people with HIV and potential opportunistic infections in resource affluent settings. We performed a prospective observational study in the Netherlands. Outpatients newly diagnosed with HIV and a CD4 T-cell count below 350 cells/mm3 and inpatients with HIV on the infectious diseases ward were included. POCUS of chest and abdomen were performed to detect opportunistic diseases and patients were followed for 1 year to register the presence or absence of opportunistic diseases as detected during routine care. Primary outcome was the number of HIV-related and unrelated conditions detected by POCUS and interobserver variation (ClinicalTrials.gov registration NCT04246983). We included 34 patients (79% males, median CD4 T-cell count 115/mm3). Observers had 97.5% agreement (Cohen's kappa for interobserver reliability 0.75). POCUS examination indicated at least one new opportunistic disease in 11 patients. In all these patients additional investigations confirmed opportunistic disease, predominantly Pneumocystis jirovecii pneumonia, bacterial pneumonia, Mycobacterium avium complex infection and lymphoma. In four patients an opportunistic disease was diagnosed in foci inaccessible for POCUS and a normal POCUS correctly excluded opportunistic diseases of the investigated structures in all patients, yielding a sensitivity of 73% and a specificity of 100%. POCUS can be a reliable, valuable addition to physical examination of people with HIV and advanced immune suppression. The data support further exploration of POCUS in people with HIV in resource affluent settings.

Incidence of nontuberculous mycobacteria infections among persons with cystic fibrosis in the United States (2010–2019)

BackgroundNontuberculous mycobacteria (NTM) are ubiquitous, environmental bacteria that can cause chronic lung disease. Persons with cystic fibrosis (pwCF) are at high risk for NTM. Approximately 1 in 5 pwCF in the United States (U.S.) is affected by pathogenic NTM species, and incidence rates of NTM have been increasing among pwCF as well as in the general population. Prevalence of NTM pulmonary infections (PI) varies widely across the United States because of geographic variation in environmental exposures. This study will present updated region-level incidence of NTM infections in the cystic fibrosis (CF) population in the U.S.MethodsWe used the Cystic Fibrosis Foundation Patient Registry (CFFPR) data for the period 2010 through 2019. Our study population comprised persons with CF ≥ 12 years of age who had been tested for NTM PI. We included only registry participants with NTM culture results. We defined incident cases as persons with one positive mycobacterial culture preceded by ≥ two negative mycobacterial cultures. We defined non-cases as persons with ≥ two negative mycobacterial cultures. We estimated average annual NTM PI incidence by region. Using quasi-Poisson models, we calculated annual percent change in incidence by region.ResultsWe identified 3,771 incident NTM infections. Of these cases, 1,816 (48.2%) were Mycobacterium avium complex (MAC) infections and 960 (25.5%) were Mycobacterium abscessus infections. The average annual incidence of NTM PI among pwCF in the U.S. was 58.0 cases per 1,000 persons. The Northeast had the highest incidence of MAC (33.5/1,000 persons tested) and the South had the highest incidence of M. abscessus (20.3/1,000 persons tested). From 2010 to 2019, the annual incidence of total NTM PI increased significantly by 3.5% per year in the U.S.ConclusionsNTM PI incidence is increasing among pwCF. Identifying high risk areas and increasing trends is important for allocating public health and clinical resources as well as evaluating interventions.

Fatty Acids Composition and HIV Infection: Altered Levels of n-6 Polyunsaturated Fatty Acids Are Associated with Disease Progression.

Fatty acids (FAs) are important regulators of immune responses and innate defense mechanisms. We hypothesized that disturbed FA metabolism could contribute to the progression of HIV infection. Plasma levels of 45 FAs were analyzed with gas chromatography in healthy controls and HIV-infected patients with regard to Mycobacterium avium complex (MAC) infection. In vitro, we assessed MAC-PPD-induced release of inflammatory cytokines in peripheral and bone marrow mononuclear cells (PBMC and BMMC) according to levels of n-6 polyunsaturated fatty acids (PUFAs). While plasma saturated FAs were higher in HIV infection, PUFAs, and in particular the n-6 PUFA arachidonic acid (AA), were lower in patients with advanced disease. The ratio between AA and precursor dihomo-γ-linolenic acid, reflecting Δ5-desaturase activity, was markedly lower and inversely correlated with plasma HIV RNA levels in these patients. Depletion of AA was observed prior to MAC infection, and MAC-PPD-induced release of TNF and IL-6 in PBMC and BMMC was lower in patients with low plasma AA. Our findings suggest that dysregulated metabolism of n-6 PUFAs may play a role in the progression of HIV infection. While high AA may contribute to chronic inflammation in asymptomatic HIV-infected patients, low AA seems to increase the susceptibility to MAC infection in patients with advanced disease.

Prevalence and risk factors of non-tuberculous mycobacterial pulmonary isolates and infection in interstitial lung disease associated with systemic autoimmune disease.

Non-tuberculous mycobacterial (NTM) lung disease (NTM-LD) prevalence is increasing worldwide. In this study, we aimed to evaluate the clinical significance of NTM pulmonary isolates (NTM-PI) and NTM-LD in patients with systemic autoimmune disease (SAD) who had a concurrent interstitial lung disease (ILD) diagnosis. We retrospectively identified patients with SAD who had a concurrent ILD diagnosis (SAD-ILD) and from whom clinically indicated sputum specimens were collected for NTM culture between 2003 and 2018 at a tertiary referral hospital. We analysed the prevalence and risk factors of NTM pulmonary isolates (NTM-PI; ≥1 positive culture) and NTM-LD (≥2 positive cultures). This study included 258 patients. Rheumatoid arthritis and Sjögren's syndrome were the most common SADs (32.2% and 26.7%, respectively). The NTM-negative subgroup had 204 patients (79.1%) and the NTM-PI subgroup had 54 patients (20.9%). In the NTM-PI subgroup, 33 patients had one NTM positive set of specimens (NTM 1+, 12.8% of the entire sample) and 21 had NTM-LD (8.1% of the entire sample). In a multivariable analysis, chronic kidney disease (CKD; adjusted odds ratio [aOR]: 3.10 [1.53, 6.29]) and chronic obstructive pulmonary disease (COPD; aOR: 2.59 [1.16, 5.78]) were significantly associated with NTM-PI. For NTM-LD, CKD (aOR: 2.79 [1.00, 7.76]) and COPD (aOR: 3.70 [1.23, 10.72]) remained significant risk factors. In patients with SAD-ILD, the NTM-PI and NTM-LD prevalence rates were 20.9% and 8.1%, respectively. COPD and CKD were independent risk factors of both NTM-PI and NTM-LD. Previous use of biological agents was associated with NTM-PI.

A Case of Mycobacterium avium Complex Vertebral Osteomyelitis in a Patient With Human Immunodeficiency Virus

Abstract Mycobacterium avium complex (MAC) infection is one of the most common bacterial opportunistic infections in persons living with human immunodeficiency virus (PLWH). Mycobacterium avium complex infections are caused by either M. avium or Mycobacterium intracellulare, which are nontuberculous mycobacterial species. Mycobacterium avium complex is prevalent in soil, water, and animals in the environment. Mycobacterium avium complex infections are commonly seen in persons with CD4 counts less than 50 cells/μL and are the most common cause of disseminated disease in immunocompromised patients. Vertebral osteomyelitis caused by MAC, however, remains uncommon in PLWH, with few cases reported in the literature (Lancet Infect Dis. 2004;4:557–565; Infect Dis Clin Pract. 2001;10:17–20). We present a case of vertebral osteomyelitis secondary to MAC in a person with human immunodeficiency virus and compare 10 other cases reported in the literature. Our case also highlights the importance of resuming secondary MAC prophylaxis when CD4 counts decline below 100 cells/μL in PLWH.

Letter: Abdominal Mycobacterium avium-intracellulare Infection—A Series in Immunocompromised and Port Site Infections

Letter: Abdominal Mycobacterium avium-intracellulare Infection—A Series in Immunocompromised and Port Site Infections

The problem of Mycobacterium abscessus complex: multi-drug resistance, bacteriophage susceptibility and potential healthcare transmission

ObjectivesMycobacterium abscessus complex is responsible for 2.6–13.0% of all non-tuberculous mycobacterial pulmonary infections and these are notoriously difficult to treat due to the complex regimens required, drug resistance and adverse effects. Hence, bacteriophages have been considered in clinical practice as an additional treatment option. Here, we evaluated antibiotic and phage susceptibility profiles of M. abscessus clinical isolates. Whole-genome sequencing (WGS) revealed the phylogenetic relationships, dominant circulating clones (DCCs), the likelihood of patient-to-patient transmission and the presence of prophages. MethodsAntibiotic susceptibility testing was performed using CLSI breakpoints (n = 95), and plaque assays were used for phage susceptibility testing (subset of n = 88, 35 rough and 53 smooth morphology). WGS was completed using the Illumina platform and analysed using Snippy/snp-dists and Discovery and Extraction of Phages Tool (DEPhT). ResultsAmikacin and Tigecycline were the most active drugs (with 2 strains resistant to amikacin, and one strain with Tigecycline MIC of 4 μg/mL). Most strains were resistant to all other drugs tested, with Linezolid and Imipenem showing the least resistance, at 38% (36/95) and 55% (52/95), respectively. Rough colony morphotype strains were more phage-susceptible than smooth strains (77%—27/35 versus 48%—25/53 in the plaque assays, but smooth strains are not killed efficiently by those phages in liquid infection assay). We have also identified 100 resident prophages, some of which were propagated lytically. DCC1 (20%—18/90) and DCC4 (22%—20/90) were observed to be the major clones and WGS identified 6 events of possible patient-to-patient transmission. DiscussionMany strains of M. abscessus complex are intrinsically resistant to available antibiotics and bacteriophages represent an alternative therapeutic option, but only for strains with rough morphology. Further studies are needed to elucidate the role of hospital-borne M. abscessus transmission.

Mycobacterium avium Complex Infections: Detailed Phenotypic and Functional Immunological Work-Up Is Required despite Genetic Analyses

Introduction: Cervical scrofulous lymphadenitis due to Mycobacterium avium complex (MAC) in immunocompetent adults is a rare disease. The presence of MAC infections demands meticulous clinical evaluation of patients along with detailed phenotypic and functional evaluation of their immune system including next-generation sequencing (NGS) analyses of target genes. Methods: Exact clinical histories of the index patients both suffering from retromandibular/cervical scrofulous lymphadenitis were obtained along with phenotypic and functional immunological evaluations of leukocyte populations followed by targeted NGS-based sequencing of candidate genes. Results: Immunological investigations showed normal serum immunoglobulin and complement levels, but lymphopenia, which was caused by significantly reduced CD3+CD4+CD45RO+ memory T-cell and CD19+ B-cell numbers. Despite normal T-cell proliferation to a number of accessory cell-dependent and -independent stimuli, the PBMC of both patients elaborated clearly reduced levels of a number of cytokines, including IFN-γ, IL-10, IL-12p70, IL-1α, IL-1β, and TNF-α upon TCR-dependent T-cell stimulation with CD3-coated beads but also superantigens. The IFN-γ production deficiency was confirmed for CD3+CD4+ helper and CD4+CD8+ cytotoxic T cells on the single-cell level by multiparametric flow cytometry irrespective of whether PMA/ionomycin-stimulated whole blood cells or gradient-purified PBMC was analyzed. In the female patient L1, targeted NGS-based sequencing revealed a homozygous c.110T>C mutation in the interferon-γ receptor type 1 (IFNGR1) leading to significantly reduced receptor expression on both CD14+ monocytes and CD3+ T cells. Patient S2 presented with normal IFNGR1 expression on CD14+ monocytes but significantly reduced IFNGR1 expression on CD3+ T cells, despite the absence of detectable homozygous mutations in the IFNGR1 itself or disease-related target genes. Exogenous addition of increasing doses of IFN-γ resulted in proper upregulation of high-affinity FcγRI (CD64) on monocytes from patient S2, whereas monocytes from patient L1 showed only partial induction of CD64 expression after incubation with high doses of IFN-γ. Conclusion: A detailed phenotypic and functional immunological examination is urgently required to determine the cause of a clinically relevant immunodeficiency, despite detailed genetic analyses.

Mycobacterium chimaera infections in cardiothoracic surgery patients exposed to heating and cooling devices despite infection control measures

Background: LivaNova 3T heating and cooling devices (HCDs) have been associated with Mycobacterium chimaera, a Mycobacterium avium-intracellulare (MAIC) species, infections after cardiothoracic surgery. We describe our outbreak, which persisted despite escalating infection control measures. Methods: We identified patients with a positive MAIC culture following cardiothoracic surgery from January 2015 to the present at our institution. We classified these as “definite,” “possible,” or “operating room contamination” cases based on positive cultures from sterile sites, airway, or surgical specimens without evidence of infection. To identify patient or surgery characteristics associated with risk for MAIC infection, we conducted a case–control study comparing definite cases to randomly selected unmatched controls of patients over the same period without a positive MAIC culture after cardiothoracic surgery. Results: We identified 26 patients with a positive MAIC culture after cardiothoracic surgery: 13 definite, 9 possible, and 4 contamination cases. Among definite cases, the most common surgeries were valve replacements and left ventricular assist devices (5 cases each). The mean time from cardiothoracic surgery to diagnosis was 525 days. Overall, 10 (77%) cases occurred after exposure to our oldest HCDs (manufactured in 2013 or earlier). To date, 16 (62%) have undergone or are undergoing treatment for MAIC infection, and 4 (15%) have died due to NTM infection or complications. Compared to 47 controls, definite cases were associated with chronic kidney disease, implants, procedure type, use of cardiopulmonary bypass, and HCD age. Cases were not associated with time on bypass, time in the operating room, or other comorbid conditions (Table). All cases occurred despite enhanced disinfection and reorienting the HCD within the operating room, according to manufacturer recommendations. Moreover, 18 cases, including 7 definite cases, occurred after most HCDs were either deep cleaned or upgraded by the manufacturer. Also, 5 cases, including 3 possible cases and 2 contamination cases, occurred after physical separation of the HCD from the operating room. In August 2022, we purchased a fleet of glycol-cooled HCDs, and we have not identified additional MAIC cases since their deployment (Fig.). Conclusions: MAIC infections after cardiothoracic surgery were associated with procedure type, especially implants, use of cardiopulmonary bypass, and HCD age. Contrary to prior reports, neither operative nor CPB time was associated with MAIC infection after cardiothoracic surgery. The outbreak persisted despite disinfection and/or deep cleaning and reorienting HCDs within the operating room; some possible and contamination cases occurred even after moving HCDs outside the operating room. Thus, HCD water contamination events in the operating room (eg, spills from HCD tubing) may be a route of exposure, and different infection prevention measures are needed.Disclosure: None

A Case of Isolated Pulmonary Mycobacterium avium Complex Infection in an Immunocompetent Host

A 48-year-old male presented with complaints of occasional dry cough and sneezing for the past 4 months and high-resolution computed tomography chest done showed tree in bud and patchy nodular opacities in the right upper lobe and right middle lobe. He underwent bronchoscopy and bronchoalveolar lavage Gene X-pert Mycobacterium Tuberculosis (MTB) was not detected, but cytology showed granulomas and hence he was started on empirical antituberculous therapy (Isoniazid, Rifampicin, Pyrazinamide and Ethambutol (HRZE) regimen). His acid-fast bacilli C/S reports during follow-up showed growth of Mycobacterium Avium complex (MAC). Drug sensitivity testing was done and then he was started on oral rifampicin, ethambutol, and azithromycin and this regimen was continued for the next 6 months.

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.

Multiple mutations of Mycobacterium intracellulare subsp. chimaera causing false-negative reaction to the transcription-reverse transcription concerted method for pathogen detection

ObjectivesTo report an isolate of Mycobacterium intracellulare subsp. chimaera with multiple mutations in 16S ribosomal RNA (rRNA) gene, resulting in the false-negative reaction to the transcription-reverse transcription concerted (TRC) method for Mycobacterium avium-intracellulare complex. MethodsWe used TRC, polymerase chain reaction (PCR), and Matrix-assisted laser desorption/ionization Time-of-Flight/Mass Spectrometry (MALDI-TOF/MS) methods to identify a clinical isolate in 2021. Due to the discordant results between TRC and PCR or MALDI-TOF MS methods, 16S rRNA sequencing, whole-genome shotgun (WGS) sequencing, and average nucleotide identity (ANI) analysis were employed to identify the isolate. ResultsA mycobacterial isolate from a sputum sample gave negative results for the detection of Mycobacterium tuberculosis complex or M. avium-intracellulare complex by the TRC method. However, the isolate was identified as M. intracellulare by both PCR method and MALDI-TOF MS method. WGS sequencing of 16S rRNA genome revealed eight substitution mutations and one insertion mutation within the region, which could hamper the correct reaction to TRC method. Subsequent ANI analysis between the isolate and various species of nontuberculosis mycobacteria revealed that the isolate could be identified as M. intracellulare subsp. chimaera. ConclusionRare mutations within the 16S rRNA genome resulted in the false-negative identification of Mycobacterium chimaera by the TRC method. WGS sequencing and ANI analysis was necessary to identify the isolate.

Mycobacterium Avium Complex Infection of the Spine in a Patient Without Acquired Immune Deficiency Syndrome: A Case Report and Literature Review

A 52-year-old patient misdiagnosed with spinal tuberculosis was successfully diagnosed with Mycobacterium avium infection using metagenomic next-generation sequencing and cured with four-drug combination protocol chemotherapy (amikacin, rifampicin, clarithromycin, ethambutol) and spinal fixation.

Analysis of time for diagnosis of nontuberculous mycobacterial lung disease and its associated factors in a tuberculosis-designated hospital in Shanghai

Objective: To investigate the pathogenic characteristics, bacteriological diagnosis time and its associated factors among patients with nontuberculous mycobacterial (NTM) lung disease in a large tuberculosis-designated hospital in Shanghai from 2020 to 2021, in order to improve diagnosis efficiency and formulate precision treatment. Methods: On the basis of the Tuberculosis Database in Shanghai Pulmonary Hospital, NTM patients diagnosed by the Department of Tuberculosis between January 2020 and December 2021 were screened. Demographic, clinical and bacterial information were retrospectively collected. Chi-square test, paired-sample nonparametric test and logistic regression model were used to analyze the factors associated with the diagnosis time of NTM lung disease. Results: A total of 294 patients with bacteriologically confirmed NTM lung disease were included in this study, 147 males and 147 females with a median age of 61(46, 69) years. Of them, 227 (77.2%) patients had comorbidity of bronchiectasis. Species identification results showed that Mycobacterium Avium-Intracellulare Complex was the main pathogen of NTM lung disease (56.1%), followed by Mycobacterium kansasii (19.0%) and Mycobacterium abscessus (15.3%). Species such as Mycobacterium xenopi and Mycobacterium malmoense were rarely identified, accounting for a total proportion of only 3.1%. Positive culture rates for sputum, bronchoalveolar lavage fluid and puncture fluid were 87.4%, 80.3% and 61.5%, respectively. Paired-sample analysis showed that the positive rate of sputum culture was significantly higher than that of smear microscopy (87.1% vs. 48.4%, P<0.01), while no statistical difference was observed between sputum and bronchoalveolar lavage fluid on positive culture rate (78.7% vs. 77.3%, P>0.05). Patients with cough or expectoration were observed with 4.04-fold (95%CI 1.80-9.05) or 2.95-fold (95%CI 1.34-6.52) higher probability of positive sputum culture, compared to those without. Regarding bronchoalveolar lavage fluid, female or patients with bronchiectasis had a 2.82-fold (95%CI 1.16-6.88) or 2.38-fold (95%CI 1.01-5.63) higher probability to achieve a positive culture. The median time to diagnosis of NTM lung disease was 32 (interquartile range: 26-42) days. The results of multivariable analysis showed that patients with symptom of expectoration (aOR=0.48, 95%CI 0.29-0.80) needed a shorter diagnosis time in comparison with patients without expectoration. With Mycobacterium Avium-Intracellulare Complex as a reference, lung disease caused by Mycobacterium abscessus needed shorter diagnosis time (aOR=0.43, 95%CI 0.21-0.88), whereas those caused by rare NTM species were observed to require a longer diagnosis time (aOR=8.31, 95%CI 1.01-68.6). Conclusion: The main pathogen causing NTM lung disease in Shanghai was Mycobacterium Avium-Intracellulare Complex. Sex, clinical symptoms and bronchiectasis had an impact on the positive rate of mycobacterial culture. The majority of patients in study hospital were timely diagnosed. Clinical symptoms and NTM species were associated with the bacteriological diagnosis time of NTM lung disease.

Disseminated Mycobacterium avium Complex Infection in a Patient Treated With Immunosuppressants

Mycobacterium avium complex (MAC) is an important cause of opportunistic infections in immunosuppressed hosts, such as patients with HIV infection and solid organ transplant recipients. MAC disease usually presents in 4 distinct clinical categories: chronic pulmonary disease, disseminated disease, skin/soft-tissue infection, and superficial lymphadenitis. However, clinical reports on gastrointestinal (GI) MAC disease are rare, especially in patients without HIV infection or a history of organ transplantation. We describe a case of non-HIV-associated GI MAC disease in a patient with long-term mycophenolate mofetil use. In this case, MAC organisms in the GI tract and ascites were observed. Endoscopy revealed a unique colonic image with large, deep epithelial denudations. This suggests that apart from patients with HIV infection or transplant recipients, those treated with immunosuppressants can have disseminated MAC. Therefore, internal physicians need to monitor patients undergoing mycophenolate mofetil immunosuppressant therapy.