Mycobacterium xenopi Genotype Associated with Clinical Phenotype in Lung Disease.

Mycobacterium xenopi is responsible for pulmonary disease (PD) in Europe and Canada. Despite its high prevalence and increasing clinical importance, little is known about the genetic diversity of M. xenopi. Through a prospective study for M. xenopi strain type and the relation to clinical phenotype, 39 patients with M. xenopi PD were analyzed. Our study demonstrated that sequence type (ST) 5 was dominant in Ontario among 15 distinct STs and caused PD in people even without underlying lung disease, whereas disease due to non-ST5 was found almost exclusively in patients with underlying lung disease.

Lung cavitation due to Mycobacterium xenopi in a renal transplant recipient.

Mycobacterium xenopi is an unusual pathogen and few such cases have been reported in the literature. We report the case of a patient with a sirolimus-based immunosuppressive regimen, who developed lung cavitation. M. xenopi was isolated from the sputum. The patient was treated initially with rifampicin, isoniazid, and pyrazinamide; levofloxacin was added to the treatment regimen after M. xenopi was demonstrated. A possible relationship between sirolimus and M. xenopi infection has been postulated, probably due to the combination of pulmonary toxicity and cellular immunosuppression of rapamycin.

Hemoptisis en mujer joven inmunocompetente / Hemoptysis in a young immunocompetent woman

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Mycobacterium xenopi multiplies within human macrophages and enhances HIV replication in vitro.

Mycobacterium xenopi can cause opportunistic infections, particularly in persons infected with human immunodeficiency virus type 1 (HIV-1). The primary focus of this effort was to determine if M. xenopi isolates could survive and grow in human peripheral blood macrophage (MPhi), and if these isolates could promote the replication of HIV-1 in vitro. M. xenopi bacilli survived and replicated 10-fold within 48 h in human MPhi while avirulent Mycobacterium smegmatis, did not grow within the MPhi. M. xenopi bacilli when cultured with peripheral blood mononuclear cells enhanced HIV-1 replication 30- and 50-fold with the macrophage-tropic HIV-1(Ba-L) and 50- and 75-fold with T-cell-tropic strain HIV-1(LAI) by 6 days post-infection when compared to M. smegmatis. The enhanced HIV replication was associated with increased production of TNF-alpha. Partial inhibition of HIV-1 induction was observed using a neutralizing anti-TNF-alpha monoclonal antibody, pentoxifylline, and matrix metalloproteinase (MMP) inhibitor I. Similar mechanisms of pathogenesis among mycobacterial species may help elucidate better treatment approaches in HIV co-infected persons.

Mycobacterium xenopi pneumonia in the southeastern United States.

Mycobacterium xenopi (M. xenopi) is a slow-growing, nontuberculous mycobacterium (NTM). This organism is found in fresh water and has been isolated in water samples collected from water systems in homes and hospitals. Before the acquired immunodeficiency syndrome epidemic, M. xenopi infection was infrequent and occurred in clusters; however, M. xenopi is now a recognized cause of pulmonary infection in immunocompetent patients with preexisting lung disease. The classic chest x-ray appearance is cavitary apical pulmonary disease, which mimics tuberculosis. M. xenopi is currently one of the most common NTM pathogens in parts of England and Canada and has been reported in parts of the northeastern United States. Whether the isolation of M. xenopi from our patient in Tennessee represents a new geographic distribution of this organism or technologic advancements that now allow for reliable identification is debatable. This case serves as a reminder to clinicians that the incidence of NTM infection is rising in the United States and that unusual NTM are capable of causing disease even in patients who are not immunocompromised.

[Mycobacterium xenopi: epidemiological and bacteriological features]. / Mycobacterium xenopi: caractères épidémiologiques et bactériologiques.

Mycobacterium xenopi is a scotochromogenic slow-growing atypical mycobacteria, with a thermostable catalase, no production of niacin and whose cell wall contains types I and VI long-chain fatty acids. Cosmopolitan, it is mainly recovered in tap-warm water. The contamination occurs through aerosol inhalation, water ingestion or use of contaminated medical or surgical equipment. M. xenopi is an opportunistic pathogen; the infection is facilitated by the incidental introduction of the bacteria in the body, pre-existing pulmonary lesions and an immunodepression. M. xenopi is mainly involved in infections of lungs, bones and joints. The treatment consists in the combination of three or four antibiotics, among rifampicin, rifabutin, ethambutol, macrolides, amikacin and fluoroquinolones.

Mycobacteria other than tuberculosis with an emphasis on Mycobacterium xenopi in clinical specimens from AIDS patients at the University Hospital of Vienna from 1989 to 1996.

This study was carried out to provide an overview of the frequency of various mycobacterial species isolated from AIDS patients at the University Hospital of Vienna from 1989 to 1996. Mycobacterium xenopi was found to be the second most common nontuberculous mycobacterial species (92 specimens from 30 patients) and was cultured predominantly from respiratory tract specimens. In 55% of patients, chest X-rays taken at the time of isolation demonstrated pathologic changes which could not be attributed to another cause. Therefore, according to our results, Mycobacterium xenopi should be viewed as an infectious agent rather than a contaminant in AIDS patients.