Detailed analysis of the radiographic presentation of Mycobacterium kansasii lung disease in patients with HIV infection

Mycobacterium kansasii

The incidence of Mycobacterium kansasii varies widely over time and by region, but this organism remains one of the most clinically relevant isolated species of nontuberculous mycobacteria. In contrast to other common nontuberculous mycobacteria, M. kansasii is infrequently isolated from natural water sources or soil. The major reservoir appears to be tap water. Infection is likely acquired through the aerosol route, with low infectivity in regions of endemicity. Human-to-human transmission is thought not to occur. Clinical syndromes and radiological findings of M. kansasii infection are mostly indistinguishable from that of Mycobacterium tuberculosis, thus requiring microbiological confirmation. Disseminated disease is uncommon in HIV-negative patients and usually associated with severe immunosuppression. The majority of patients with M. kansasii pulmonary disease have underlying pulmonary comorbidities, such as smoking, chronic obstructive pulmonary disease, bronchiectasis, and prior or concurrent M. tuberculosis infection. Surveys in Great Britain, however, noted higher rates, with 8 to 9% of M. kansasii infections presenting with extrapulmonary disease. Common sites of extrapulmonary disease include the lymph nodes, skin, and musculoskeletal and genitourinary systems. The specificity of gamma interferon release assays (IGRAs) for M. tuberculosis may be reduced by M. kansasii infection, as M. kansasii encodes CFP-10 and ESAT-6, two antigens targeted by IGRAs. A study conducted to evaluate the therapy in rifampin-resistant disease found that patients with acquired rifampin resistance were treated with daily high-dose ethambutol, isoniazid, sulfamethoxazole, and pyridoxine combined with aminoglycoside therapy. Given the potential toxicities, particularly with aminoglycoside therapy, clarithromycin and/or moxifloxacin therapy could be considered as alternatives.

Risk Factors Associated With Quantitative Evidence of Lung Emphysema and Fibrosis in an HIV-Infected Cohort

INTRODUCTION

The disease spectrum for HIV-infected individuals has shifted toward comorbid non-AIDS conditions including chronic lung disease, but quantitative image analysis of lung disease has not been performed.

OBJECTIVES

To quantify the prevalence of structural changes of the lung indicating emphysema or fibrosis on radiographic examination.

METHODS

A cross-sectional analysis of 510 HIV-infected participants in the multicenter Lung-HIV study was performed. Data collected included demographics, biological markers of HIV, pulmonary function testing, and chest computed tomographic examinations. Emphysema and fibrosis-like changes were quantified on computed tomographic images based on threshold approaches.

RESULTS

In our cohort, 69% was on antiretroviral therapy, 13% had a current CD4 cell count less than 200 cells per microliter, 39% had an HIV viral load greater than 500 copies per milliliter, and 25% had at least a trace level of emphysema (defined as >2.5% of voxels <-950HU). Trace emphysema was significantly correlated with age, smoking, and pulmonary function. Neither current CD4 cell count nor HIV viral load was significantly correlated with emphysema. Fibrosis-like changes were detected in 29% of the participants and were significantly correlated with HIV viral load (Pearson correlation coefficient = 0.210; P < 0.05); current CD4 cell count was not associated with fibrosis. In multivariable analyses including age, race, and smoking status, HIV viral load remained significantly correlated with fibrosis-like changes (coefficient = 0.107; P = 0.03).

CONCLUSIONS

A higher HIV viral load was significantly associated with fibrosis-like changes, possibly indicating early interstitial lung disease, but emphysematous changes were not related to current CD4 cell count or HIV viral load.

Human infections due to nontuberculous mycobacteria: the infectious diseases and clinical microbiology specialists' point of view

Nontuberculous mycobacteria (>150 species such as Mycobacterium avium, Mycobacterium kansasii, Mycobacterium chelonae and Mycobacterium abscessus) are opportunistic pathogens causing lung and extrarespiratory infections, beside M. ulcerans and M. marinum that are pathogens causing specific skin and soft tissue infections. Disseminated infections occur only in severe immunosuppressed conditions such as AIDS. The diagnosis is based on repeated isolations of the same mycobacterium associated with clinical and radiological signs, and the absence of tuberculosis. Precise species identification is obtained by molecular biology. Therapeutic antibiotic regimens differ with regard to the mycobacterial species that are involved. Prevention of iatrogenic infections relies on using sterile water in all injections, healthcare and cosmetic occupations. Future perspectives are to set effective antibiotic regimens tested in randomized therapeutic trials.

Molecular characterisation of clinical and environmental isolates of Mycobacterium kansasii isolates from South African gold mines

Mycobacterium kansasii (M. kansasii) is a major cause of non-tuberculous mycobacterial pulmonary disease in the South African gold-mining workforce, but the source of infection and molecular epidemiology are unknown. This study investigated the presence of M. kansasii in gold and coal mine and associated hostel water supplies and compared the genetic diversity of clinical and environmental isolates of M. kansasii. Five M. kansasii and ten other potentially pathogenic mycobacteria were cultured mainly from showerhead biofilms. Polymerase chain reaction-restriction analysis of the hsp65 gene on 196 clinical and environmental M. kansasii isolates revealed 160 subtype I, eight subtype II and six subtype IV strains. Twenty-two isolates did not show the typical M. kansasii restriction patterns, suggesting that these isolates may represent new subtypes of M. kansasii. In contrast to the clonal population structure found amongst the subtype I isolates from studies in other countries, DNA fingerprinting of 114 clinical and three environmental subtype I isolates demonstrated genetic diversity amongst the isolates. This study demonstrated that showerheads are possible sources of M. kansasii and other pathogenic non-tuberculous mycobacterial infection in a gold-mining region, that subtype I is the major clinical isolate of M. kansasii strain and that this subtype exhibits genetic diversity.

Non-tuberculous mycobacterial infections at San Francisco General Hospital

BACKGROUND AND AIMS

The epidemiology of non-tuberculous mycobacteria (NTM) infection is not well defined. We evaluated the trends in incidence of NTM infections at San Francisco General Hospital (SFGH), a large metropolitan county hospital.

METHODS

We performed a retrospective review of microbiologic and clinical records of all patients with a positive NTM culture reported from 1993 to 2001. NTM infection was defined by the isolation of >1 NTM from any clinical specimen. Patients were stratified by human immunodeficiency virus (HIV) status. Univariate and multivariate logistic regression were used to identify factors that were independently associated with NTM infection. Trends over time were assessed using Poisson test for trend.

RESULTS

During the study period, 25 736 samples from 7395 patients were cultured for mycobacteria. Of these samples, 2853 (11.1%) from 1345 patients (18.2%) were culture positive for NTM. Patient characteristics associated with infection included younger age (P < 0.001), male gender (P < 0.001), White ethnicity compared with Asian and Hispanic (P < 0.001 and P = 0.01, respectively), and HIV positivity (P < 0.001). Overall, NTM infection at SFGH decreased significantly from 319 cases in 1993 to 59 in 2001 (P < 0.001). Mycobacterium avium was predominant in both HIV-positive and HIV-negative populations (74.5% and 44.6% of isolates, respectively), and Mycobacterium kansasii was the second most common NTM species isolated. The proportion of other NTM species isolated in these groups differed.

CONCLUSION

In contrast to other published studies, time-series analyses show that NTM isolation rates decreased during the study period at SFGH, where NTM was most strongly associated with HIV infection.

Protective effects of Korean red ginseng against radiation-induced apoptosis in human HaCaT keratinocytes

Radiation-induced oral mucositis is a dose-limiting toxic side effect for patients with head and neck cancer. Numerous attempts at improving radiation-induced oral mucositis have not produced a qualified treatment. Ginseng polysaccharide has multiple immunoprotective effects. Our aim was to investigate the effectiveness of Korean red ginseng (KRG) on radiation-induced damage in the human keratinocyte cell line HaCaT and in an in vivo zebrafish model. Radiation inhibited HaCaT cell proliferation and migration in a cell viability assay and wound healing assay, respectively. KRG protected against these effects. KRG attenuated the radiation-induced embryotoxicity in the zebrafish model. Irradiation of HaCaT cells caused apoptosis and changes in mitochondrial membrane potential (MMP). KRG inhibited the radiation-induced apoptosis and intracellular generation of reactive oxygen species (ROS), and stabilized the radiation-induced loss of MMP. Western blots revealed KRG-mediated reduced expression of ataxia telangiectasia mutated protein (ATM), p53, c-Jun N-terminal kinase (JNK), p38 and cleaved caspase-3, compared with their significant increase after radiation treatment. The collective results suggest that KRG protects HaCaT cells by blocking ROS generation, inhibiting changes in MMP, and inhibiting the caspase, ATM, p38 and JNK pathways.

HIV and tuberculosis: a deadly human syndemic

A syndemic is defined as the convergence of two or more diseases that act synergistically to magnify the burden of disease. The intersection and syndemic interaction between the human immunodeficiency virus (HIV) and tuberculosis (TB) epidemics have had deadly consequences around the world. Without adequate control of the TB-HIV syndemic, the long-term TB elimination target set for 2050 will not be reached. There is an urgent need for additional resources and novel approaches for the diagnosis, treatment, and prevention of both HIV and TB. Moreover, multidisciplinary approaches that consider HIV and TB together, rather than as separate problems and diseases, will be necessary to prevent further worsening of the HIV-TB syndemic. This review examines current knowledge of the state and impact of the HIV-TB syndemic and reviews the epidemiological, clinical, cellular, and molecular interactions between HIV and TB.

An official ATS workshop report: Emerging issues and current controversies in HIV-associated pulmonary diseases

Pulmonary diseases are major causes of morbidity and death in persons with HIV infection. Millions of people with HIV/AIDS throughout the world are at risk of opportunistic pneumonias such as tuberculosis, bacterial pneumonia, and Pneumocystis pneumonia. However, the availability of combination antiretroviral therapy has turned HIV into a chronic disease, and noninfectious lung diseases such as lung cancer, chronic obstructive pulmonary disease, and pulmonary arterial hypertension are also emerging as important causes of illness. Despite the importance of these diseases and the rapidly evolving understanding of their pathogenesis and epidemiology, few avenues exist for the discussion and dissemination of new clinical and basic insights. In May of 2008, the American Thoracic Society sponsored a 1-day workshop, "Emerging Issues and Current Controversies in HIV-Associated Pulmonary Diseases," which brought together basic and clinical researchers in HIV-associated pulmonary disease. A review of the literature was performed by workshop participants, and the workshop included 18 presentations on diverse topics summarized in this article.

Nontuberculous mycobacterial lung disease

PURPOSE OF REVIEW

There is increasing awareness that nontuberculous mycobacteria (NTM) lung diseases are becoming more prevalent. Nontuberculous mycobacterial diseases could legitimately be seen as an emerging public-health threat.

RECENT FINDINGS

Nontuberculous mycobacterial lung disease associated radiographically with nodules and bronchiectasis occurs primarily in women. These patients are associated with a specific morphotype, including low BMI, tall stature, scoliosis, pectus excavatum and mitral valve prolapse. The pathophysiologic link between these findings and the development of bronchiectasis and NTM disease remains unclear. As with tuberculosis, the tumor-necrosis factor alpha (TNF-alpha) blockers also predispose to NTM infection that can be severe. The most frustrating aspect of NTM therapy remains the generally poor correlation between in-vitro antibiotic susceptibility and in-vivo response to antimicrobials. A possible insight into this phenomenon is the recent discovery of an inducible macrolide resistance (erm) gene in Mycobacterium fortuitum and Mycobacterium abscessus. This gene can produce in-vivo resistance without resulting in a 'resistant' MIC for macrolides.

SUMMARY

The NTM pose an increasing problem for clinicians and are associated with significant obstacles that thwart successful treatment of NTM disease. Continued progress in the areas of disease pathogenesis and therapy will improve the outlook for these patients.

Current treatment of atypical mycobacteriosis

BACKGROUND

Atypical mycobacteria are a heterogeneous group of organisms that are of increasing importance because of the growing number of infections they cause. This rising rate of infection is due mainly to the increase in the number of susceptible (and especially immunosuppressed) patients.

OBJECTIVE

To revise the currently used treatment schemes of the most commonly isolated atypical mycobacteria.

METHODS

Literature review using reference books and PubMed with specific keywords for each mycobacteria.

RESULTS/CONCLUSION

The first important step in the management of atypical mycobacteria is to recognize the true infections caused by these organisms. The treatment required varies according to species. Well-characterized combinations exist for most common isolates, with the use of first-line antituberculous drugs (isoniazid, rifampin, ethambutol), clarithromycin, aminoglycosides and/or quinolones for slowly growing species (Mycobacterium avium complex, Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium ulcerans, Mycobacterium marinum, Mycobacterium lentiflavum, Mycobacterium malmoense) and macrolides, quinolones, amikacin and other antibiotics for rapidly growing mycobacteria (Mycobacterium abscessus, Mycobacterium chelonae, Mycobacterium fortuitum). Surgical therapy is also important for some species (Mycobacterium ulcerans, Mycobacterium scrofulaceum) and for localized infections. The treatment of uncommon species is not well defined and is determined by the results of in vitro tests of individual strains. Because of the increasing number of resistant strains, new antibiotics need to be used for the treatment of these strains.

Acute immune response to Mycobacterium massiliense in C57BL/6 and BALB/c mice

Mycobacterium massiliense is an environmental opportunistic pathogen that has been associated with soft tissue infection after minor surgery. We studied the acute immune response of C57BL/6 and BALB/c mice infected intravenously with 10(6) CFU of an M. massiliense strain isolated from a nosocomial infection in Brazil. The results presented here show that M. massiliense is virulent and pathogenic to both C57BL/6 and BALB/c mice, inducing a granulomatous inflammatory reaction that involves the activation of macrophages, dendritic cells, and natural killer cells induced by gamma interferon and interleukin-17 (IL-17) in C57BL/6 mice and by IL-12 in BALB/c mice.