Effect of multidrug therapy on the prognosis of Mycobacterium avium complex pulmonary disease.

Multidrug therapy for Mycobacterium avium complex pulmonary disease (MAC-PD) results in negative sputum cultures. However, the prognostic value of this treatment approach remains unclear. This study aimed to clarify whether multidrug therapy reduces the incidence of events related to MAC-PD and improves the mortality rate. Patients who met the diagnostic criteria for MAC-PD at our hospital between 2003 and 2019 were retrospectively evaluated using medical records. Events related to MAC-PD were defined as hospitalisation for haemoptysis or respiratory infection and the development of chronic respiratory failure. There were 90 and 108 patients in the multidrug and observation groups, respectively. The median observation period was 86 months. Intergroup differences in body mass index, proportion of patients with cavities, and erythrocyte sedimentation rate were not significant. However, the observation group was older with a higher mean age (multidrug group: 62 years, observation group: 69 years; P < 0.001) and had a higher proportion of male patients (multidrug group: 13/90 [14.4%], observation group: 35/108 [32.4%]; P < 0.01). Furthermore, intergroup differences in the incidence of events related to MAC-PD (multidrug group: 26.69/1000 person-years, observation group: 25.49/1000 person-years), MAC-PD-associated mortality rate (multidrug group: 12.13/1000 person-years, observation group: 12.74/1000 person-years), and total mortality (multidrug group: 24.26/1000 person-years, observation group: 29.50/1000 person-years) were not significant. Many patients relapse even after multidrug therapy, and our findings suggest that multidrug therapy has no effect in preventing the onset of respiratory events or prolonging life expectancy.

A Rapid Screening Assay for Clarithromycin-Resistant Mycobacterium avium Complex Using Melting Curve Analysis with Nonfluorescent Labeled Probes.

Mycobacterium avium complex (MAC) thrives in various environments and mainly causes lung disease in humans. Because macrolide antibiotics such as clarithromycin or azithromycin are key drugs for MAC lung disease, the emergence of macrolide-resistant strains prevents the treatment of MAC. More than 95% of macrolide-resistant MAC strains are reported to have a point mutation in 23S rRNA domain V. This study successfully developed a melting curve assay using nonfluorescent labeled probes to detect the MAC mutation at positions 2058 to 2059 of the 23S rRNA gene (AA genotype, clarithromycin susceptible; TA, GA, AG, CA, AC, and AT genotypes, clarithromycin resistant). In the AA-specific probe assay, the melting peak of the DNA fragment of the AA genotype was higher than that of DNA fragments of other genotypes. Melting temperature (Tm) values of the AA genotype and the other genotypes were about 80°C and 77°C, respectively. DNA fragments of each genotype were identified correctly in six other genotype-specific probes (TA, GA, AG, CA, AC, and AT) assays. Using genomic DNA from six genotype strains of M. avium and four genotype strains of M. intracellulare, we confirmed that all genomic DNAs could be correctly identified as individual genotypes according to the highest Tm values among the same probe assays. These results indicate that this melting curve-based assay is able to determine MAC genotypes at positions 2058 to 2059 of the 23S rRNA gene. This simple method could contribute to the rapid detection of clarithromycin-resistant MAC strains and help to provide accurate drug therapy for MAC lung disease. IMPORTANCE Since macrolide antibiotics such as clarithromycin or azithromycin are key drugs in multidrug therapy for Mycobacterium avium complex (MAC) lung diseases, the rapid detection of macrolide-resistant MAC strains has important implications for the treatment of MAC. Previous studies have reported a correlation between drug susceptibility testing and the mutation of macrolide resistance genes. In this study, we developed a novel melting curve-based assay using nonfluorescent labeled probes to identify both clarithromycin-resistant M. avium and M. intracellulare with mutations in the 23S rRNA gene, which is the clarithromycin or azithromycin resistance gene. This assay contributed to not only the detection of MAC mutations but also the determination of all genotypes at positions 2058 to 2059 of the 23S rRNA gene. Furthermore, because nonfluorescent labeled probes are used, this assay is more easily and more immediately available than other methods.

Vacuum sealing drainage: A novel treatment method for primary cutaneous Mycobacterium intracellulare infection.

The incidence of primary cutaneous Mycobacterium intracellulare infection is very low. We report a case of primary cutaneous M. intracellulare infection which presented as painful erythematous swelling of the right upper limb without systemic involvement. A novel technique of vacuum sealing drainage was successfully implemented after antimycobacterial treatment proved ineffective at the end of 3 months. Our technique also revealed some additional practical advantages.

Mycobacterium indicus pranii protein MIP_05962 induces Th1 cell mediated immune response in mice.

Utility of Mycobacterium indicus pranii (MIP) as a multistage vaccine against mycobacterial infections demands identification of its protective antigens. We explored antigenicity and immunogenicity of a candidate protein MIP_05962 that depicts homology to HSP18 of M. leprae and antigen1 of Mycobacterium tuberculosis. This protein elicited substantial antibody response in immunized mice along with modulation of cellular immune response towards protective Th1 type. Both CD4+ and CD8+ subsets from immunized mice produced hallmark protective cytokines, IFN-γ, TNF-α and IL-2. This protein also enhanced the CD4+ effector memory that could act as first line of defence during infections. These results point to MIP_05962 as a protective antigen that contributes, in conjunction with others, to the protective immunity of this live vaccine candidate.

Nontuberculous mycobacterial empyema in an immunocompetent child.

Nontuberculous mycobacterium (NTM) species are mycobacterial species other than those belonging to the Mycobacterium Tuberculosis complex and Mycobacterium leprae. There are very few reports of NTM in immunocompetent children causing empyema. In this article, we report a 9-year-old immunocompetent girl who presented with Mycobacterium avium-intracellulare empyema.

Safety and tolerability of clofazimine as salvage therapy for atypical mycobacterial infection in solid organ transplant recipients.

BACKGROUND: The treatment of Mycobacterium avium complex (MAC) requires prolonged, multidrug therapy, which is often not well tolerated. In solid organ transplant (SOT) recipients, drug-drug interactions complicate treatment further. Failure or intolerance requires the use of salvage regimens, and clofazimine is one of the drugs that can be used. No data are available on the safety and tolerability of clofazimine for the treatment of MAC in SOT recipients. METHODS: Retrospective review of all SOT recipients treated for MAC infection with clofazimine at a large transplant center between 2006 and 2013. RESULTS: Five SOT recipients received clofazimine as salvage therapy. Transplanted organs were lungs in 3 patients, and kidney and liver in 1 patient each. Infection was diagnosed at a median of 22 months (range 4-57) post transplant. Sites of infection were the lungs in 2 patients, and septic arthritis, mesenteric, and disseminated disease in 1 patient each. All patients received standard anti-MAC therapy for a median of 26 weeks (range 18-45) before starting clofazimine. Indications for use of clofazimine included a lack of response to previous therapy (3 patients), and poor tolerance of other regimens (3 patients). All patients received at least 2 additional drugs besides clofazimine. Median duration of clofazimine-containing regimen was 8 months (range 2-18). Clofazimine was discontinued because of gastrointestinal intolerance in 1 of the 5 patients. The most common adverse event from clofazimine was skin discoloration, in 60% of patients. No hepatotoxicity or hematologic toxicity occurred. Microbiological clearance and resolution of clinical disease was documented in 2 of 5 patients; and 2 of the 5 patients died of other causes while on therapy. CONCLUSIONS: Clofazimine appears safe and may be considered as a salvage therapeutic option in SOT recipients with MAC infection who are intolerant or unresponsive to standard therapy. The small sample size does not allow conclusions regarding efficacy.

[Nontuberculous mycobacterial infections of the lung]. / Atypische Mykobakteriose der Lunge.

Nontuberculous mycobacterium (NTM) species are mycobacterial species other than those belonging to the Mycobacterium tuberculosis complex and M. leprae. NTM are generally free-living organisms that are ubiquitous in the environment. Pulmonary disease, especially in older persons with and without underlying lung disease, is caused primarily by M. avium complex (MAC) and M. kansasii. The symptoms and signs of MAC lung disease are variable and not specific, but include cough, malaise, weakness, dyspnoea, chest discomfort and occasionally hemoptoe. Two major clinical presentations include disease in those with underlying lung disease, primarily white, middle-aged or elderly men - often alcoholics and/or smokers with underlying chronic obstructive lung disease, patients in whom MAC develops in areas of prior bronchiectasis, and patients with cystic fibrosis; and those without known underlying lung disease, including non-smoking women over age 50 who have interstitial patterns on chest radiography. M. kansasii infections are endemic in cities with infected tap water. Symptoms of the M. kansasii lung disease resemble to tuberculosis. M. abszessus is the most pathogenic rapid growing Mycobacterium which causes pulmonary infection. The American Thoracic Society and Infectious Disease Society of America's diagnostic criteria for nontuberculous mycobacterial pulmonary infections include both imaging studies consistent with pulmonary disease and recurrent isolation of mycobacteria from sputum or isolated from at least one bronchial wash in a symptomatic patient. For treatment of MAC lung disease we recommend depending on severity and susceptibility testing a three to four drug treatment with a macrolide, rifampicin and ethambutol and for M. kansasii a treatment with Isoniazid, rifampicin and ethambutol. Surgical management only plays a role in rare and special cases. Treatment should be continued until sputum cultures are consecutively negative for at least one year.

Hypercalcemia in two patients with sarcoidosis and Mycobacterium avium intracellulare not mediated by elevated vitamin D metabolites.

INTRODUCTION: To describe 2 unusual cases of hypercalcemia due to granulomatous diseases with normal vitamin D metabolites and no other ready explanation for the hypercalcemia. METHODS: We present the clinical, laboratory and pathologic findings of 2 patients with hypercalcemia and review previous reports of hypercalcemia in granulomatous diseases without elevated vitamin D metabolites. RESULTS: Hypercalcemia was described in various granulomatous diseases including sarcoidosis, tuberculosis, berylliosis, leprosy and, rarely, in fungal infections. Elevated serum level of vitamin D or its metabolites was linked to the pathogenesis of hypercalcemia in these disorders. The authors present the clinical, laboratory and pathologic findings in 2 patients who presented with hypercalcemia and normal vitamin D metabolites with no other ready explanation for the hypercalcemia. The first patient was diagnosed with Mycobacterium avium, whereas the second patient was found to have sarcoidosis. CONCLUSION: Although hypercalcemia in granulomatous diseases has been attributed to be mediated by elevated vitamin D metabolites, there have been several case reports that documented normal values of active vitamin D metabolites. This report illustrates the regulatory feedback mechanisms of vitamin D synthesis and introduces the term "inappropriately normal" vitamin D metabolites levels in light of low levels of parathyroid hormone.

[Novel type of antimicrobial mechanism in host macrophages against mycobacterial infections].

Macrophages (M(phi)s) play a central role as anti-microbial effector cells in the expression of host resistance to mycobacterial infections. With respect to antimicrobial effector molecules of host M(phi) against mycobacterial pathogens, recent studies suggest the possibility that the reactive nitrogen intermediates (RNI)--and reactive oxygen intermediates-independent antimycobacterial mechanism(s) may be crucial for the antimycobacterial function of host M(phi). In this context, we previously found that free fatty acids (FFAs) such as arachidonic acid (AA) and linolenic acid exhibited potent antimicrobial activity against mycobacterial organisms, including Mycobacterium tuberculosis (MTB) and Mycobacterium avium complex (MAC). In addition, FFAs in combination with RNI played critical roles in manifestation of the activity of M(phi) against mycobacterial organisms. Moreover, our recent studies have shown the following findings. First, anti-MTB activity of IFN-gamma-activated M(phi)s was specifically blocked by arachidonyl trifluoromethylketone (aTFMK), an inhibitor of cytosolic phospholipase A2 (cPLA2). Second, ATP potentiated the anti-MAC bactericidal activity of M(phi)s cultivated in the presence of clarithromycin and rifamycin. This effect of ATP was closely related to intracellular Ca2+ mobilization and was specifically blocked by aTFMK. Third, intramacrophage translocation of membranous AA molecules to MAC-containing phagosomes was also specifically blocked by aTFMK. In the confocal microscopic observation of MAC-infected M(phi)s, ATP enhanced the intracellular translocation of cPLA2 into MAC-containing phagosomes. These findings suggest that FFAs (especially AA) produced by the enzymatic action of cPLA2 play important roles as antimycobacterial effectors in the expression of M(phi) antimicrobial activity against mycobacterial pathogens.

Mechanism of thioamide drug action against tuberculosis and leprosy.

Thioamide drugs, ethionamide (ETH) and prothionamide (PTH), are clinically effective in the treatment of Mycobacterium tuberculosis, M. leprae, and M. avium complex infections. Although generally considered second-line drugs for tuberculosis, their use has increased considerably as the number of multidrug resistant and extensively drug resistant tuberculosis cases continues to rise. Despite the widespread use of thioamide drugs to treat tuberculosis and leprosy, their precise mechanisms of action remain unknown. Using a cell-based activation method, we now have definitive evidence that both thioamides form covalent adducts with nicotinamide adenine dinucleotide (NAD) and that these adducts are tight-binding inhibitors of M. tuberculosis and M. leprae InhA. The crystal structures of the inhibited M. leprae and M. tuberculosis InhA complexes provide the molecular details of target-drug interactions. The purified ETH-NAD and PTH-NAD adducts both showed nanomolar Kis against M. tuberculosis and M. leprae InhA. Knowledge of the precise structures and mechanisms of action of these drugs provides insights into designing new drugs that can overcome drug resistance.

Misidentification of Mycobacterium leprae as Mycobacterium intracellulare by the COBAS AMPLICOR M. intracellulare test.

Commercially available nucleic acid probe- and amplification-based systems for detection and differentiation of mycobacteria are widely used in clinical microbiology laboratories. Here we report two cases of human leprosy in which the COBAS AMPLICOR Mycobacterium intracellulare test led to false- positive results. Correct identification of Mycobacterium leprae was possible only by amplification and comparative sequence analysis of the 16S rRNA gene.

Cutaneous Mycobacterium avium intracellulare infection in an HIV+ patient mimicking histoid leprosy.

Cutaneous infections with Mycobacterium avium intracellulare (MAI) are uncommon in healthy patients but may arise in those with underlying immunocompromise, including patients with HIV. Their clinical manifestations are protean. We report an AIDS patient with a cutaneous MAI infection that clinically and histopathologically mimicked histoid leprosy, a presentation not previously described in this population.

Treatment of Mycobacterium avium-intracellulare complex lung disease with a macrolide, ethambutol, and clofazimine.

BACKGROUND: Mycobacterium avium-intracellulare (MAC) causes progressive lung disease. Recommended treatment regimens include a macrolide and a rifamycin, but drug intolerance and relapse after treatment is completed often limit successful therapy. METHODS: Consecutive individuals referred for treatment of MAC lung disease were treated with a regimen that included either clarithromycin, 500 mg bid, or azithromycin, 250 mg/d, on weekdays; ethambutol, 15 mg/kg/d; and clofazimine, 100 mg/d. The intention was to treat patients for a minimum of 12 months. The diagnosis of MAC lung disease was confirmed by multiple positive sputum culture findings in patients with typical symptoms and radiologic findings. RESULTS: Thirty patients (27 women and 3 men; mean age, 70 +/- 9.4 years [SD]) were treated. A total of 22 of the patients reported adverse effects from clarithromycin or azithromycin. Intolerance of clarithromycin resulted in the withdrawal of four patients before sputum conversion. The remaining patients continued treatment for an average of 10 months, and sputum findings converted to negative in all 26 patients (87%). One patient died of unrelated causes while still receiving therapy, and five patients (19%) relapsed an average of 17 months after treatment was completed. CONCLUSIONS: Treatment with a macrolide, ethambutol, and clofazimine was successful in 20 of 30 patients (67%) with MAC lung disease and is a reasonable alternative to rifamycin-containing regimens.

Association of DRB1*1501 with disseminated Mycobacterium avium complex infection in North American AIDS patients.

The HLA class II allele, DR2 (DRB1*1501), has been repeatedly found to be associated with development of tuberculosis and leprosy. We searched for associations of these and other class II alleles with disseminated Mycobacterium avium complex infection (DMAC) in North American Caucasian homosexual AIDS patients. Molecular typing for HLA-DRB1 and -DQB1 alleles in 176 cases of DMAC and 176 matched controls showed an association of accelerated onset of disease with DRB1*1501 (and the closely linked DQB1*0602) that was stronger upon adjustment for the degree and duration of CD4+ cell deficiency (P=0.04) and in multivariate analysis (P=0.02) than in unadjusted analysis. A similar trend was seen with DRB1*0701, and no other allele showed a relationship of similar magnitude. M. avium complex organisms may more effectively evade host defenses in individuals carrying an HLA polymorphism identical to that associated with M. tuberculosis and M. leprae.