Mycobacterium Avium Intracellulare

Mycrobacterium Avium Intracellulare – General Information

Mycobacterium Avium Intracellulare is usually considered the same bacteria with M. intracellulare because both bacterias cause tuberculosis (TB; M tuberculosis). In the United States, they are described as Mycrobacterium avium complex (MAC). MAI organisms are found in soils, like potted plant soil and also in tap water throughout the world. These organisms enter in peoples bodies through food, water or inhaled dust and it probably can’t be transmitted from one person to another. In the United States, by the early 1990s, people with AIDS were commonly reported to be infected with this bacterium, founding that 43% of people, after two years since they were diagonsticated with AIDS, had detectable Mai organisms in their blood. This bacterium is usually encountered in people who are HIV-infected. If they have CD4 counting less than 100 cells/mm3, and often below 20 cells/mm3, MAI can infect almost any organ, especially the liver, spleen and bone marrow. They mainly infect cells of the reticuloendothelial system, a group of related cells in the body that includes macrophages. But in people with healthy immune systems, Mycobacterium Avium Intracellulare rarely causes illness.

Nowadays highly active antiretroviral therapy (HAART), decreases the incidence of Mycobacterium Avium Intracellulare among HIV-infected people and people who have been diagnosticated with MAI, making them live longer. Avoiding certain foods or mineral water is not protective against MAI infection because Mycrobacterium Avium is common in the environment. People can also have in their organism undetectable to MAI organisms, making MAI infection less preventive.

Mycrobacterium Avium Intracellulare – Symptoms

Mycrobacterium Avium Intracellulare – Treatment

Mycobacterium avium-M. intracellulare (MAI) is the most frequent cause of opportunistic bacterial infection in patients with AIDS. Previous studies have indicated that liposome-encapsulated aminoglycosides are highly effective in treating MAI infections in mice. We investigated whether the fluoroquinolone sparfloxacin is effective in treating MAI infection in the murine macrophage-like cell line J774. Sparfloxacin was encapsulated in the membrane phase of multilamellar liposomes composed of phosphatidylglycerol-phosphatidylcholine-cholesterol (1:1:1 molar ratio). Mycrobaterium Avium Intracellulare-infected macrophages were treated for either 24 h or 4 days with free or liposome-encapsulated sparfloxacin. Treatment with free or liposome-encapsulated sparfloxacin (6 micrograms/ml) for 24 h resulted in the reduction of the growth index to 25 and 30% of that of untreated controls, respectively. When cultures were treated for 4 days, free sparfloxacin reduced the growth index to 6% of that of the untreated control, while liposome-encapsulated sparfloxacin reduced it to 8% of that of the control. MAI treatment should generally consist of a combination of two or more drugs, one of which should be clarithromycin or azithromycin. Ethambutol is commonly the second drug prescribed in addition to azithromycin or clarithromycin. Side effects of clarithromycin and azithromycin are mainly gastrointestinal such as nausea and diarrhoea, and usually mild and short-lived. Mycobacterium Avium Intracellulare organisms can become resistant to clarithromycin when the drug is used on its own, and people with resistant organisms are more likely to experience a resurgence of MAI. Doses higher than 500mg twice daily are not recommended as they have been associated with poorer survival in several clinical trials.

Other drugs used in combinations include rifampicin (Rifadin / Rimactane), gentamicin (Cidomycin /Genticin), amikacin (Amikin), ethambutol, Ciproxin (ciprofloxacin) and sparfloxacin. Ethambutol and clarithromycin are commonly prescribed together because they each enhance the strength of the other. Another drug, clofazimine, has been used in combinations, but in July 1996 American researchers warned against this drug after a study suggested that it offered no added benefits, and was associated with an increased risk of death. Clarithromycin was licensed for Mycobacterium Avium Intracellulare prophylaxis in the United States in December 1995 but has not been approved as a preventive treatment for MAI in Europe. An international trial found that it reduced the risk of developing Mycobacterium Avium Intracellulare by over two thirds compared with placebo and produced a survival advantages (Pierce 1996). Two studies which have found that clarithromycin is more effective than rifabutin at delaying MAI bacteraemia or Mycobacterium Avium Intracellulare disease among people with CD4 cell counts below 100 cells/mm3, but they did not report a survival advantage (Hewitt 1999; Benson 2000). Combining both clarithromycin and rifabutin was not significantly better than clarithromycin alone, but caused more side-effects. Azithromycin was licensed for Mycobacterium Avium Intracellulare prophylaxis in the United States in June 1996 but has not been approved as a preventive treatment for MAI in Europe. One study showed that azithromycin was more effective on its own or in combination with rifabutin monotherapy at preventing MAI bacteraemia (Havlir 1996). It can be taken in a convenient once-weekly dose. However, 11% of people who developed MAI despite taking an azithromycin-containing regimen had resistant MAI strains. Mycobacterium Avium Intracellulare strains that are resistant to azithromycin are also resistant to clarithromycin, and vice versa. A trial of clofazimine monotherapy was stopped as it appeared to have no effect in preventing MAI.