Evolution toward extremely high imipenem resistance in Mycobacterium abscessus outbreak strains.

Treatment of Mycobacterium abscessus pulmonary disease requires multiple antibiotics including intravenous ß-lactams (e.g., imipenem). M. abscessus produces a ß-lactamase (BlaMab) that inactivates ß-lactam drugs but less efficiently carbapenems. Due to intrinsic and acquired resistance in M. abscessus and poor clinical outcomes, it is critical to understand the development of antibiotic resistance both within the host and in the setting of outbreaks. We compared serial longitudinally collected M. abscessus subsp. massiliense isolates from the index case of a cystic fibrosis center outbreak and four outbreak-related strains. We found strikingly high imipenem resistance in the later patient isolates, including the outbreak strain (MIC > 512 µg/mL). The phenomenon was recapitulated upon exposure of intracellular bacteria to imipenem. Addition of the ß-lactamase inhibitor avibactam abrogated the resistant phenotype. Imipenem resistance was caused by an increase in ß-lactamase activity and increased blaMab mRNA level. Concurrent increase in transcription of the preceding ppiA gene indicated upregulation of the entire operon in the resistant strains. Deletion of the porin mspA coincided with the first increase in MIC (from 8 to 32 µg/mL). A frameshift mutation in msp2 responsible for the rough colony morphology and a SNP in ATP-dependent helicase hrpA cooccurred with the second increase in MIC (from 32 to 256 µg/mL). Increased BlaMab expression and enzymatic activity may have been due to altered regulation of the ppiA-blaMab operon by the mutated HrpA alone or in combination with other genes described above. This work supports using carbapenem/ß-lactamase inhibitor combinations for treating M. abscessus, particularly imipenem-resistant strains.

Notes from the Field: Potential Outbreak of Extrapulmonary Mycobacterium abscessus subspecies massiliense Infections from Stem Cell Treatment Clinics in Mexico - Arizona and Colorado, 2022.

Mycobacterium abscessus is an intrinsically drug-resistant, rapidly growing, nontuberculous mycobacterium; extrapulmonary infections have been reported in association with medical tourism (1). During November-December 2022, two Colorado hospitals (hospitals A and B) treated patient A, a Colorado woman aged 30-39 years, for M. abscessus meningitis. In October 2022, she had received intrathecal donor embryonic stem cell injections in Baja California, Mexico to treat multiple sclerosis and subsequently experienced headaches and fevers, consistent with meningitis. Her cerebrospinal fluid revealed neutrophilic pleocytosis and grew M. abscessus in culture at hospital A. Hospital A's physicians consulted hospital B's infectious diseases (ID) physicians to co-manage this patient (2).

A Case of IgA Nephropathy Complicated with Pulmonary Infection by Mycobacterium Abscess.

BACKGROUND: In August 2023, our hospital confirmed a case of IgA nephropathy complicated with pulmonary infection by Mycobacterium abscess. The patient sought medical attention at our hospital due to "gross hematuria for 10 years, recurrence for 10 days, coughing and sputum production". The patient had pulmonary tuberculosis 15 years ago and had been cured. He had bronchiectasis for 10 years. METHODS: Chest CT, fiberoptic bronchoscopy examination, urine routine (urine analysis + sediment quantification), urine trace protein measurement//urine creatinine (random urine), urine protein quantification (24-hour urine), antinuclear antibody measurement (ANA), sputum culture, alveolar lavage fluid bacterial culture, alveolar lavage fluid acid fast staining, and alveolar lavage fluid mNGS. RESULTS: Chest CT: Cystic dilation of bronchi in both lungs, mainly in the lower lungs, with visible phlegm clots inside. Fibrobronchoscopy: A large amount of white foam like secretions can be seen in the lumens of the middle lobe of the right lung and the lower lobes of both lungs. Urinary routine (urine analysis + sediment quantification): protein+↑, occult blood+++. Urine Microprotein Determination//Urine Creatinine (Random Urine): Microalbumin 156.00 mg/L, Urine mALB/Urine Creatinine 132.73 mg/g; Quantitative determination of urine protein (24-hour urine): total protein 0.93 g/24-hour urine; Antinuclear antibody assay (ANA): weakly positive; Sputum bacterial culture: negative; Bacterial culture of bronchoalveolar lavage fluid: Mycobacterium abscess++, NGS in bronchoalveolar lavage fluid: Mycobacterium abscess. Clinical treatment plan: 0.25 g of azithromycin qd po+ 0.4 g of amikacin sulfate qd ivgtt+ 1 g cefmetazole sodium q12hours ivgtt. After 10 days of treatment, the patient improved and was discharged. CONCLUSIONS: This article reports a case of IgA nephropathy complicated with pulmonary abscess mycobacterial infection. Mycobacterium abscess was quickly and accurately identified by mNGS. Reasonable treatment measures were adopted clinically. The patient improved and was discharged. This study has important reference significance for the clinical diagnosis and treatment of Mycobacterium abscess infection. In addition, mNGS, as a novel detection method, has considerable prospects for rapid diagnosis of pathogens.

Multiple Postoperative Lung Infections after Thymoma Surgery Diagnosed as Nontuberculous Mycobacterial Infection.

BACKGROUND: Thymomas are thymic epithelial-derived, most common primary anterior mediastinal masses. Non-tuberculous mycobacteria (NTM) are species that do not cause leprosy and belong to species outside the Mycobacterium tuberculosis complex. METHODS: With the clinical application of targeted next-generation sequencing (tNGS), we promptly confirmed a case of NTM infection combined with NTM infection after thymoma surgery, and we performed a joint literature analysis of the two diseases to improve clinicians' understanding and recognition of lung infections after thymoma surgery. RESULTS: Chest CT of both lungs showed multiple hyperdense shadows. Sputum bacterial culture and characterization detected Neisseria Dryad and Streptococcus Grass Green. The presence of Mycobacterium abscessus infection was confirmed by alveolar lavage fluid sent for second-generation macro gene sequencing. CONCLUSIONS: The body's immune function decreases after thymoma surgery. When empirical anti-infection treatment for recurrent pneumonia in the lungs is ineffective, we should be alerted to the possibility of the presence of pulmonary non-tuberculous mycobacterial infection, and next-generation sequencing should be performed promptly to arrive quickly at a diagnosis.

Mycobacterium Infection of Abscess with Hemoptysis as the Initial Manifestation.

BACKGROUND: Mycobacterium abscessus is a new pathogen in recent years, which belongs to non-tuberculosis mycobacterium. Mycobacterium abscessus is widely involved in many nosocomial infections and secondary aggravation of genetic respiratory diseases. Mycobacterium abscessus is naturally resistant to most antibiotics and is difficult to treat. We report a case of mycobacterium abscessus infection with hemoptysis as the first manifestation. METHODS: Bronchoscopy, next-generation sequencing (NGS). RESULTS: Acid-fast staining of bronchoscopic lavage fluid showed that a small amount of acid-fast bacilli could be seen. NGS test showed the presence of Mycobacterium abscess, sequence number 137 (reference range ≥ 0), and symptomatic treatment against non-tuberculosis mycobacteria. CONCLUSIONS: For the follow-up infection of patients with hemoptysis, the treatment effect of antibiotics is not good, so the pathological tissue should be obtained by bronchoscopy or percutaneous lung biopsy in time, and the diagnosis should be confirmed by NGS if necessary.

Three Cases of Non-Tuberculosis Mycobacterium Skin Infection Outbreak in Beauty Institutions.

BACKGROUND: From June 2021 to July 2021, our hospital confirmed 3 cases of Mycobacterium infection in skin abscesses. All 3 patients underwent thread embedding and weight loss surgery at the same informal beauty institution, with a history of silk protein injection. None of the patients had any other underlying diseases or surgical history. Symptoms and signs show that the disease is acute and the course of the disease is short. All patients have found subcutaneous masses in different parts of the body. In most cases, the masses show redness and swelling, and some of the masses are accompanied by tenderness, wave sensation, and rupture. After some of the masses rupture, purulent secretions can be seen. METHODS: The pus secreted by the skin lesions of the three patients were cultured to a single bacterium, which was identified by MALDI-TOF MS. Multiple locus sequence typing (MLST) was performed using three specific genes (hsp65, rpoB, and secA1) and seven housekeeping genes (argH, cya, glpK, gnd, murC, pta, and purH). The results were queried through the MLST database of Mycobacterium abscess. RESULTS: All three strains of bacteria were Mycobacterium abscess type ST279 massiliense subtype. Three antibacterial drugs including cefmetazole, amikacin, and clarithromycin were administered in combination with 5-aminolevulinic acid photodynamic therapy (ALA-PDT). After 3 - 6 months, there was no obvious redness or swelling in the surrounding tissues of the wound, and no obvious purulent secretions were observed. All patients were cured and discharged from the hospital. After a follow-up of six months, there was no recurrence of the lesions. CONCLUSIONS: Medical institutions must strictly follow infection control guidelines and take preventive measures to prevent such incidents from happening again. ALA-PDT as a combination therapy for nontuberculous Mycobacterium (NTM) skin infections can improve treatment efficacy and shorten antibiotic usage time.

The epidemiology of pulmonary Mycobacterium abscessus species in Japanese population.

BACKGROUND: Mycobacterium abscessus species (MABS) is now a most virulent rapidly growing mycobacteria (RGM), and the rapid increase of MABS was recently observed worldwide, including in Japan. Thus, we gathered evidences of the presence of pulmonary MABS in Japanese population from Japanese articles. METHODS: we searched studies that addressed the isolation of pulmonary non-tuberculous Mycobacteria (NTM) or MABS from clinical respiratory specimens in Japan. RESULTS: the ratio of MABS to NTM was 3.04% (95% confidence interval [CI]: 2.51-3.68), found using the meta-analysis of single proportions. The estimated mean age of patients infected with MABS was 67.72 years (95% CI: 65.41-70.02), found using the meta-analysis of single means. The estimated proportion of females, never smoker, and the co-infection with Mycobacterium avium complex (MAC) was 66.75% (95% CI: 59.23-73.50), 67.57% (95% CI: 62.43-72.32), and 36.74% (95% CI: 25.30-49.90), respectively. The characteristics of MABS in Japan were considerably different from that in Europe and United States from the perspective of age, gender, and complications, wherein the patients in these countries tended to be younger, had lower number of females, and had more occurrences of hereditary diseases, including cystic fibrosis (CF). CONCLUSION: we hypothesized that the characteristics of MABS in the Japanese were involved in those of non-CF MABS, and the distribution of gender and age of MABS were similar to that of MAC in the Japanese.

[Solitary pulmonary nodule as an unusual presentation of infection by Mycobacterium abscessus. Report of a clinical case]. / Nódulo pulmonar solitario como presentación inhabitual de infección por Mycobacterium abscessus. Reporte de un caso clínico.

Nontuberculous mycobacteria are a ubiquitous species of bacteria that can produce chronic pulmonary infectious disease in humans. The clinical manifestations are diverse, from an indolent solitary pulmonary nodule up to fibrocavitary disease which carries a poor prognosis. The presentation as a solitary pulmonary nodule has been described in slowly growing mycobacteria, mainly Mycobacterium avium complex and Mycobacterium kansasii. In the following clinical case, we report an infection by a nontuberculous mycobacteria presenting as a solitary pulmonary nodule caused by Mycobacterium abscessus and its outcomes after surgical resection.

CLINICAL CHARACTERISTICS AND VISUAL OUTCOMES IN ENDOPHTHALMITIS AFTER KERATOPROSTHESIS IMPLANTATION.

PURPOSE: To describe the presentation, microbiology, management, and prognosis of eyes with endophthalmitis after Boston keratoprosthesis implantation. METHODS: Retrospective case series with history, diagnostics, management, and outcomes data in endophthalmitis after keratoprosthesis implantation presenting to a tertiary center between 2009 and 2020. RESULTS: Of 137 keratoprosthesis-implanted eyes, 7 eyes of 7 patients (5%) developed endophthalmitis. On presentation, 6 (86%) reported decreased visual acuity, and only 1 (14%) reported pain. Peripheral corneal ulcers were present in 2 eyes (29%). Seidel testing was negative in all cases. Six eyes (86%) had retroprosthetic membranes. One (14%) underwent initial pars plana vitrectomy with mechanical vitreous biopsy, whereas 6 (86%) received a needle vitreous tap-half of which were dry. Organisms were isolated after vitreous tap in two eyes: Streptococcus intermedius and Mycobacterium abscessus. The mean visual acuity preendophthalmitis, at presentation, and at 6 months were 20/267, 20/5,944, and 20/734, respectively. The visual acuity improved 9.08 ± 11.78 Early Treatment Diabetic Retinopathy Study lines from presentation to 6 months. Six-month visual acuity was correlated with preendophthalmitis visual acuity (r = 0.92, P = 0.003) but not presenting visual acuity (P = 0.838). CONCLUSION: Visual acuity at 6 months is correlated with preendophthalmitis visual acuity, not presenting visual acuity. Endophthalmitis should be considered in the differential diagnosis of painless intraocular inflammation any time after keratoprosthesis implantation, even if Seidel negative.

Painful Purulent Nodules Caused by Mycobacterium at Site of Lipodissolve Injections.

ABSTRACT: "Lipodissolve" (LD) is a non-FDA-approved solution of phosphatidylcholine in deoxycholate that was developed around 2004. A study of its safety reported minor and uncommon side effects including pain, tender nodules, pigmentary alterations, and ulceration at the site of injection. We present a 53-year-old woman who received LD injections bilaterally to her proximal arms. One week later, she developed painful nodules at each injection site. She was treated with a 10-day course of trimethoprim/sulfamethoxazole without improvement. An incisional biopsy was performed and showed deep dermal suppurative inflammation with numerous neutrophils and granulomas. Stains for bacteria, fungus, and acid-fast organisms were negative. Cultures for acid-fast bacilli grew Mycobacterium abscessus, sensitive to amikacin and clarithromycin. The patient was subsequently treated with intravenous amikacin, azithromycin, and bedaquiline with symptom resolution. Investigation revealed 3 similar infections linked to LD injections originating from the same physician's office. The most common organism implicated in injection infections is Staphylococcus aureus. Infections at injection sites caused by atypical mycobacteria have been reported to occur after tattooing, other types of injections, and implants. Of atypical mycobacteria, M. abscessus accounts for the greatest number of postinjection or iatrogenic infections. Common antitubercular drugs are not effective for treating atypical mycobacteria, making species identification and sensitivity testing imperative for treatment. This case highlights an unusual infection caused by cosmetic injections of LD, previously reported to be associated with minimal side effects, and the importance of examination for acid-fast bacilli and follow-up with culture, even in the absence of organisms identified on stained sections.

Mycobacterium abscessus virulence traits unraveled by transcriptomic profiling in amoeba and macrophages.

Free-living amoebae are thought to represent an environmental niche in which amoeba-resistant bacteria may evolve towards pathogenicity. To get more insights into factors playing a role for adaptation to intracellular life, we characterized the transcriptomic activities of the emerging pathogen Mycobacterium abscessus in amoeba and murine macrophages (Mϕ) and compared them with the intra-amoebal transcriptome of the closely related, but less pathogenic Mycobacterium chelonae. Data on up-regulated genes in amoeba point to proteins that allow M. abscessus to resist environmental stress and induce defense mechanisms, as well as showing a switch from carbohydrate carbon sources to fatty acid metabolism. For eleven of the most upregulated genes in amoeba and/or Mϕ, we generated individual gene knock-out M. abscessus mutant strains, from which ten were found to be attenuated in amoeba and/or Mϕ in subsequence virulence analyses. Moreover, transfer of two of these genes into the genome of M. chelonae increased the intra-Mϕ survival of the recombinant strain. One knock-out mutant that had the gene encoding Eis N-acetyl transferase protein (MAB_4532c) deleted, was particularly strongly attenuated in Mϕ. Taken together, M. abscessus intra-amoeba and intra-Mϕ transcriptomes revealed the capacity of M. abscessus to adapt to an intracellular lifestyle, with amoeba largely contributing to the enhancement of M. abscessus intra-Mϕ survival.

Isolation of non-tuberculous mycobacteria among tuberculosis patients, a study from a tertiary care hospital in Lahore, Pakistan.

BACKGROUND: There is scarce knowledge on the prevalence of diseases caused by non-tuberculous mycobacteria (NTM) in Pakistan. In the absence of culture and identification, acid-fast bacilli (AFB) causing NTM disease are liable to be misinterpreted as tuberculosis (TB). Introduction of nucleic acid amplification testing for Mycobacterium tuberculosis complex (MTBC) offers improved diagnostic accuracy, compared with smear microscopy, and also assists in differentiating MTBC from other mycobacteria. This study aimed to investigate the prevalence of NTM among patients investigated for TB and describe NTM disease and treatment outcomes at a tertiary care hospital in Pakistan. METHODS: This is a retrospective study, data on NTM isolates among culture-positive clinical samples over 4 years (2016-19) was retrieved from laboratory records. Information on clinical specimens processed, AFB smear results, and for the AFB positive isolates, results of species identification for MTBC, and for NTM isolates, results of species characterization and drug susceptibility testing was collected. Additional clinical data including patient characteristics, treatment regimens, and outcomes were collected for patients with NTM disease treated at Gulab Devi Hospital, Lahore. RESULTS: During the study period, 12,561 clinical specimens were processed for mycobacterial culture and 3673 (29%) were reported positive for AFB. Among these 3482 (95%) were identified as MTBC and 191 (5%) as NTM. Among NTM, 169 (88%) were isolated from pulmonary and 22 (12%) from extrapulmonary specimens. Results of NTM speciation were available for 60 isolates and included 55% (n = 33) M. avium complex and 25% (n = 15) M. abscesses. Among these patients, complete clinical records were retrieved for 12 patients with pulmonary disease including nine infected with M. avium complex and three with M. abscessus. All 12 patients had a history of poor response to standard first-line anti-TB treatment. Ten patients were cured after 18 months of treatment, whereas, one with M. abscessus infection died and another was lost to follow up. CONCLUSION: In TB endemic areas, NTM can be misdiagnosed as pulmonary TB leading to repeated failed anti-TB treatment and increased morbidity, emphasizing the need for improved diagnosis.

Glycopeptidolipid Genotype Correlates With the Severity of Mycobacterium abscessus Lung Disease.

BACKGROUND: Smooth and rough colony morphotypes of Mycobacterium abscessus are associated with virulence, but some isolates form both smooth and rough colonies, impeding successful morphotype identification. Reportedly, smooth/rough morphotypes are also related to the glycopeptidolipid (GPL) genotype. However, the accuracy of GPL genotyping to discriminate morphotypes and the relationship between GPL genotype and clinical characteristics of M abscessus lung disease have not been verified. METHODS: A retrospective analysis of colony morphology, GPL genotype, and clinical data from 182 patients with M abscessus lung disease was conducted. RESULTS: Of 194 clinical isolates, 126 (65.0%), 15 (7.7%), and 53 (27.3%) exhibited rough, smooth, and mixed colony morphotypes, respectively. Glycopeptidolipid genotyping indicated that 86.7% (13 of 15) of smooth isolates belonged to the GPL-wild type (WT) group, whereas 98.4% (124 of 126) of rough isolates belonged to the GPL-mutant type (MUT) group. Therefore, GPL genotyping accurately distinguished between smooth and rough morphotypes. Mixed colony morphotypes were also divided into GPL-WT (18.9%) and GPL-MUT (81.1%) groups. Further analysis revealed that patients infected with the GPL-MUT group presented with significantly worse baseline clinical characteristics and exacerbated episodes of lung disease. CONCLUSIONS: Glycopeptidolipid genotyping accurately distinguishes smooth and rough colony morphotypes. Patients infected with the GPL-MUT genotype exhibit worse clinical characteristics and are at a higher risk of exacerbated lung disease.

TBAJ-876, a 3,5-Dialkoxypyridine Analogue of Bedaquiline, Is Active against Mycobacterium abscessus.

Lung disease caused by Mycobacterium abscessus is very difficult to cure, and treatment failure rates are high. The antituberculosis drug bedaquiline (BDQ) is used as salvage therapy against this dreadful disease. However, BDQ is highly lipophilic, displays a long terminal half-life, and presents a cardiotoxicity liability associated with QT interval prolongation. Recent medicinal chemistry campaigns resulted in the discovery of 3,5-dialkoxypyridine analogues of BDQ which are less lipophilic, have higher clearance, and display lower cardiotoxic potential. TBAJ-876, a clinical development candidate of this series, shows attractive in vitro antitubercular activity and efficacy in a murine tuberculosis model. Here, we asked whether TBAJ-876 is active against M. abscessus TBAJ-876 displayed submicromolar in vitro activity against reference strains representing the three subspecies of M. abscessus and against a collection of clinical isolates. Drug-drug potency interaction studies with commonly used anti-M. abscessus antibiotics showed no antagonistic effects, suggesting that TBAJ-876 could be coadministered with currently used drugs. Efficacy studies, employing a mouse model of M. abscessus infection, demonstrated potent activity in vivo In summary, we demonstrate that TBAJ-876 shows attractive in vitro and in vivo activities against M. abscessus, similar to its BDQ parent. This suggests that next-generation BDQ, with improved tolerability and pharmacological profiles, may be useful for the treatment of M. abscessus lung disease in addition to the treatment of tuberculosis.

The synergetic effect of Imipenem-clarithromycin combination in the Mycobacteroides abscessus complex.

BACKGROUND: Nontuberculous mycobacteria (NTM) are ubiquitous organisms and the incidence of NTM infections has been increasing in recent years. Mycobacteroides abscessus (M. abscessus) is one of the most antimicrobial-resistant NTM; however, no reliable antibiotic regimen can be officially advocated. We evaluated the efficacy of clarithromycin in combination with various antimicrobial agents against the M. abscessus complex. RESULTS: Twenty-nine clinical strains of M. abscessus were isolated from various clinical samples. Of the isolates, 10 (34.5%) were of M. abscessus subsp. abscessus, 18 (62.1%) of M. abscessus subsp. massiliense, and 1 (3.4%) of M. abscessus subsp. bolletii. MICs of three antimicrobial agents (amikacin, imipenem, and moxifloxacin) were measured with or without clarithromycin. The imipenem-clarithromycin combination significantly reduced MICs compared to clarithromycin and imipenem monotherapies, including against resistant strains. The association between susceptibility of the M. abscessus complex and each combination of agents was significant (p = 0.001). Adjusted residuals indicated that the imipenem-clarithromycin combination had the synergistic effect (adjusted residual = 3.1) and suppressed the antagonistic effect (adjusted residual = - 3.1). In subspecies of M. abscessus complex, the association with susceptibility of M. abscessus subsp. massiliense was similarly statistically significant (p = 0.036: adjusted residuals of synergistic and antagonistic effect respectively: 2.6 and - 2.6). The association with susceptibility of M. abscessus subsp. abscessus also showed a similar trend but did not reach statistical significance. CONCLUSION: Our data suggest that the imipenem-clarithromycin combination could be the recommended therapeutic choice for the treatment of M. abscessus complex owing to its ability to restore antimicrobial susceptibility.

Mycobacterium abscessus subsp. abscessus empyema complicated with subcutaneous abscess.

There have been no case reports of thoracic subcutaneous abscess after surgery for Mycobacterium abscessus complex associated empyema. We herein report a case of Mycobacterium abscessus subsp. abscessus (M. abscessus subsp. abscessus) induced subcutaneous abscesses following surgical treatment for concurrent M. abscessus subsp. abscessus -associated empyema and pneumothorax. A 75-year-old woman had M. abscessus subsp. abscessus -associated empyema and pneumothorax. She underwent surgical treatment of decortication and fistulectomy and suffered from M. abscessus subsp. abscessus -associated subcutaneous abscesses after thoracentesis/drainage. A multidisciplinary approach combined with surgical care, thermal therapy, and multidrug chemotherapy contributed to a successful result. An early multidisciplinary approach is believed to be important in cases of M. abscessus subsp. abscessus -associated empyema and subcutaneous abscess.

Molecular characterization of Mycobacterium abscessus subspecies isolated from patients attending an Italian Cystic Fibrosis Centre.

Mycobacterium abscessus (MABS) infection represents significant management challenge in cystic fibrosis (CF) patients. This retrospective study (2005-2016) aims to determine the prevalence of the subspecies of MABS isolated from CF patients, to evaluate the persistence over the years of a single subspecies of MABS and to correlate mutations responsible for macrolides and amikacin resistance with MIC values. We investigated 314 strains (1 isolate/patient/year) isolated from the lower respiratory tract of 51 chronically infected CF patients. Sequencing of rpoB gene was performed to identify the MABS subspecies. The erm(41) gene was sequenced to differentiate the strains with and without inducible macrolide resistance. Regions of 23S and 16S rRNA were sequenced to investigate mutations responsible for constitutive resistance to macrolides and aminoglycosides, respectively. Antibiotic susceptibility, using commercial microdilution plates, was evaluated according to CLSI. M. abscessus subsp. abscessus accounted for 64% of the isolates, bolletii subspecies for 16% and massiliense subspecies for 20%. All the massiliense strains presented truncated erm(41) gene while 12 abscessus strains presented the mutation T28->C in the erm(41) gene, which makes it inactive. The 23S rRNA analysis did not show constitutive resistance to macrolides in any strain. Mutation of the 16S rRNA gene was highlighted in 2 strains out of 314, in agreement with high MIC values. The correct identification at the subspecies level and the molecular analysis of 23S rRNA, 16S rRNA and erm gene is useful to guide the treatment strategy in patients with M. abscessus lung infection.

[In vitro evaluation of the antibacterial activity of nemonoxacin against Mycobacterium tuberculosis, Mycobacterium intracellulare and Mycobacterium abscessus].

Objective: To test the in vitro antibacterial activity of nemonoxacin against clinically isolates of Mycobacterium tuberculosis complex(MTBC), Mycobacterium intracellulare(MI) and Mycobacterium abscessus(MA). Methods: Totally 128, 80 and 50 isolates of MTBC, M.intracellulare and M.abscessus were tested, respectively. The minimum inhibitory concentrations (MICs) of nemonoxacin and levofloxacin against the strains of the three most frequently isolated mycobacterium species were measured by double dilution method with micro-well plate. Results: The MICs of 104(81.2%) strains of MTBC isolates against levofloxacin were ≤ 1 µg/ml. Whereas 112 (87.5%) strains of MTBC isolates had MICs against nemonoxacin than>1 µg/ml, furthermore, the MICs of 88(68.8%)strains of MTBC isolates against nemonoxacin were≥4 µg/ml. The median MIC of M. intracellulare isolates against levofloxacin and nenofloxacin were 16 and 32 µg/ml, separately, while were 16 µg/ml and 8 µg/ml for M. abscessus, respectively. The ratios of nemonoxacin MIC/levofloxacin MIC of M. abscessus were between 0.125-1.000. Conclusions: Nemonoxacin presented weaker inhibitory activity than levofloxacin against M. tuberculosis, whereas it had better activity than levofloxacin against M. abscessus.

[Mycobacterium abscessus complex representatives in patients with bronchopulmonary pathology: prevalence, peculiarities of cultivation and identification.]

More and more publications appear in the modern literature on the increase in the prevalence of non-tuberculous mycobacteria (NTMs), in particular, representatives of M. chelonae / Mycobacterium abscessus complex (MABSc). The paper presents data on the current classification of M. chelonae / Mycobacterium abscessus complex and its main representatives. The main data on the possible sources and ways of infection of MABSc patients in hospital are presented. The main features of cultivation on various nutrient media and their possible identification using modern methods are also indicated. The main risk factors for the development of mycobacteriosis in patients and the possible clinical picture are described. The prevalence of MABSc representatives in the structure of non-tuberculous mycobacteria isolated from clinical material from 483 patients from the Samara region was assessed for examination for tuberculosis, and the prevalence from 933 patients with cystic fibrosis (CF) from 55 regions of the Russian Federation from 2016 to 2019 was estimated. In total, as a result of the study, 316 NTM strains (65.4%) were isolated and identified in the first group of patients. M.abscessus was isolated and identified 10 strains and 5 strains - M.chelonae, which amounted to 3.2% and 1.6%, respectively, of all NTMs. In general, MABSc representatives were isolated in 3.1% of the examined patients. As a result of a screening study of patients with CF, 14194 microorganism strains from 933 patients were isolated and identified. Altogether M. abscessus was isolated and confirmed from 14 patients of different ages. Thus, the prevalence of MABSc among the examined patients with CF in the Russian Federation was 1.5%.

HMGN2 regulates non-tuberculous mycobacteria survival via modulation of M1 macrophage polarization.

Non-tuberculous mycobacteria (NTM), also known as an environmental and atypical mycobacteria, can cause the chronic pulmonary infectious diseases. Macrophages have been suggested as the main host cell to initiate the innate immune responses to NTM infection. However, the molecular mechanism to regulate the antimicrobial immune responses to NTM is still largely unknown. Current study showed that the NTM clinical groups, Mycobacterium abscessus and Mycobacterium smegmatis, significantly induced the M1 macrophage polarization with the characteristic production of nitric oxide (NO) and marker gene expression of iNOS, IFNγ, TNF-α, IL1-ß and IL-6. Interestingly, a non-histone nuclear protein, HMGN2 (high-mobility group N2), was found to be spontaneously induced during NTM-activated M1 macrophage polarization. Functional studies revealed that HMGN2 deficiency in NTM-infected macrophage promotes the expression of M1 markers and the production of NO via the enhanced activation of NF-κB and MAPK signalling. Further studies exhibited that HMGN2 knock-down also enhanced IFNγ-induced M1 macrophage polarization. Finally, we observed that silencing HMGN2 affected the survival of NTM in macrophage, which might largely relevant to enhanced macrophage polarization into M1 phenotype under the NTM infection. Collectively, current studies thus suggested a novel function of HMGN2 in regulating the anti-non-tuberculous mycobacteria innate immunity of macrophage.