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Results for “Mycobacterium avium Complex”

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PubMed1998

Randomized, open-label trial of azithromycin plus ethambutol vs. clarithromycin plus ethambutol as therapy for Mycobacterium avium complex bacteremia in patients with human immunodeficiency virus infection. Veterans Affairs HIV Research Consortium.

Disseminated Mycobacterium avium complex (MAC) infection continues to be a common opportunistic infection in patients infected with human immunodeficiency virus (HIV). The optimal therapy for disseminated MAC infection is unclear. We compared azithromycin plus ethambutol with clarithromycin plus ethambutol in the treatment of disseminated MAC infection in HIV type 1-infected patients, examining the frequency of bacteremia clearance, time to clearance, and study drug tolerance after 16 weeks of therapy. Fifty-nine patients for whom blood cultures were positive for MAC were enrolled in the study from 10 university-affiliated Veterans Affairs Medical Centers. Thirty-seven patients were evaluable for determination of quantitative bacteremia and clinical outcomes. Clearance of bacteremia was seen at the final visit in 37.5% of azithromycin-treated patients and in 85.7% of clarithromycin-treated patients (P = .007). The estimated median time to clearance of bacteremia was also significantly different between the two treatment arms: 4.38 weeks for clarithromycin recipients vs. > 16 weeks for azithromycin recipients (P = .0018). Only one isolate developed macrolide resistance during therapy. Abatement of symptoms, other laboratory-evident abnormalities, and adverse effects were similar in the two groups. At the doses used in this study, clarithromycin/ethambutol produced a more rapid resolution of bacteremia than did azithromycin/ethambutol, and clarithromycin/ethambutol was more effective at sterilization of blood cultures after 16 weeks of therapy.

AIDS-Related Opportunistic Infections↗

PubMed1991

Effect of agitation of BACTEC 13A blood cultures on recovery of Mycobacterium avium complex.

The effect of agitation of BACTEC 13A bottles (Becton Dickinson) on the recovery of Mycobacterium avium complex (MAC) from blood was compared with that of static incubation. A total of 265 blood specimens was inoculated in duplicate into BACTEC 13A bottles. One specimen was statically incubated at 35 degrees C, and the other was incubated with agitation on a Gyrotory shaker at 35 degrees C for the first 2 weeks and thereafter without shaking for up to 12 weeks. Of the 265 specimens, 77 (29.1%) were positive in either one or both of the paired bottles. The average detection times for the shaken and nonshaken bottles were 12.7 and 15.9 days, respectively. A total of 10.4% of the specimens in the shaken bottles became positive 1 week before those in the nonshaken bottles, and 16.9% of the shaken cultures were positive more than 2 weeks before their counterparts. A further 46.8% of the agitated specimens became positive while the corresponding nonagitated cultures remained negative. When both specimens became positive at the same time, 88% of the shaken cultures had higher growth indices than their nonshaken counterparts. A further 11 paired blood cultures were taken from patients known to be infected with MAC to assess the effect of agitation of bottles on the utility of making twice-weekly readings during the first 2 weeks of incubation. Ten of the 11 sets of specimens in the shaken bottles were positive 1 or more weeks before those in the corresponding nonshaken bottles. In the remaining set, both specimens became positive on the same day; however, the growth index of the agitated culture was higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteremia↗

PubMed1995

Isolation and characteristics of Mycobacterium avium complex from water and soil samples in Uganda.

SETTING: Mycobacterium avium complex organisms have not been isolated from late stage AIDS patients in Uganda. This could possibly be due to the absence of M. avium complex in the Uganda environment. OBJECTIVE AND DESIGN: Determine whether M. avium complex organisms could be isolated from water and soils collected in the living environment of Ugandan AIDS patients. RESULTS: Representatives of the M avium complex were isolated from 3 of 7 (43%) water and 3 of 7 (43%) soil samples collected in Kampala, Uganda. The average number of colony-forming units per ml water was 3.3 and average colony-forming units per gram of soil was 7825. In terms of growth characteristics, antimicrobial susceptibility patterns, and the presence or absence of plasmids and IS901, Ugandan M. avium complex isolates were similar to those isolated from the US and European AIDS patients and their environment. CONCLUSIONS: M. avium complex organisms sharing genetic and physiological characteristics of M. avium complex isolates recovered from patients with AIDS can be isolated from water and soil samples in Uganda.

Colony Count, Microbial↗

PubMed1981

Pathology and tuberculin sensitivity in cattle inoculated with Mycobacterium avium complex serotypes 6, 14 and 18.

Three strains of Mycobacterium avium complex organisms, serotypes 6, 14 and 18 isolated from typical tuberculous lesions in cattle were examined for pathogenicity and ability to sensitise cattle to avian and bovine tuberculin. Each strain caused tuberculoid granulomas at the site of subcutaneous inoculation but no lesions elsewhere. Sensitisation to bovine tuberculin was detected in the caudal fold test in 11 of 18 inoculated animals 8 weeks after injection. In a simultaneous comparative cervical test, reactions to avian tuberculin were much larger than reactions to bovine tuberculin in all inoculated animals.

Animals↗

PubMed1993

[Immunological aspects of Mycobacterium avium complex infection].

Tuberculin anergy is common in patients with Mycobacterium avium complex (MAC) infection. We examined in vitro cell-mediated immunity in these patients with MAC infection. Peripheral blood lymphocytes of patients, as compared with those of tuberculous patients or tuberculin-positive healthy donors, showed depressed in vitro blastogenic responses to purified protein derivative of tuberculin (PPD), not only to PPDs of Mycobacterium tuberculosis but also to PPD-B and PPD-Y of M. intracellulare and M. kansasii, respectively. Analysis of defective in vitro PPD-induced lymphocyte blastogenic responses in these patients revealed that PPD-induced interleukin 2 (IL-2) production was impaired whereas PPD-induced IL-2 responsiveness was normally developed after PPD stimulation. In the second half of this report, study was carried out to examine the mechanism of depressed T cell activity in these patients. Heat-killed MAC organisms and their lipid component impaired the capacity of peripheral blood lymphocytes to proliferate in vitro in response to concanavalin A (Con A), PPD, and to a lesser degree, phytohemagglutinin (PHA) stimulation. Inhibition by MAC was not contingent upon prior exposure of the donor to MAC or other mycobacteria and occurred with lymphocytes from tuberculin-negative as well as -positive subjects. The suppression was not due to the toxicity of MAC. Adherent cell depletion and cell mixing experiments with T cells indicated that monocytes and not T cells were a major contributor to the immunosuppression observed. Treatment of monocytes with MAC or MAC-derived lipid resulted in significant decreases in CD11b, a member of the LFA-1 and Leu M3 (CD14) molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed1999

Mycobacterium avium complex spinal epidural abscess in an HIV patient.

Although Mycobacterium avium complex (MAC) is the most common opportunistic bacterial infection in AIDS patients, epidural involvement is rare. A case of MAC spinal epidural abscess without vertebral osteomyelitis, that was continuous with presacral and bilateral piriformis muscle inflammation, is reported.

AIDS-Related Opportunistic Infections↗

PubMed1996

Localized cutaneous infection caused by Mycobacterium avium complex in an AIDS patient.

Although infection due to Mycobacterium avium complex (MAC) has long been recognized, it was not until the current AIDS epidemic that isolation of these mycobacteria became common in microbiology laboratories. The disseminated form of the disease is the commonest type. Localized disease as the first manifestation of MAC infection is a rare finding among these patients. Herein we report a case of localized cutaneous infection due to MAC in an AIDS patient.

AIDS-Related Opportunistic Infections↗

PubMed1995

Treatment of localized Mycobacterium avium complex infection with clofazimine and doxycycline in a cat.

Mycobacterium avium complex infection resulted in a granuloma that developed at the base of the left ear in a cat. The lesion caused vestibular dysfunction and facial palsy on the left side and protruded into the oral cavity on that side. The cat was treated successfully, with resolution of the lesion and elimination of the organism, by use of combined administration of clofazimine and doxycycline. Adverse effects of the clofazimine treatment included temporary reddish-orange discoloration of the cat's skin and mucous membranes.

Animals↗

PubMed2001

[Mycobacterium avium complex in water buffaloes slaughtered for consumption].

Two mycobacterium strains isolated from lung tissue a apical lymph nodes of slaughtered water buffaloes were biochemically analyzed and identified as Mycobacterium avium complex strains. Association between these microorganisms and the acquired immunodeficiency syndrome, and the potential risk posed by eating infected animals and their products, was discussed.

Animals↗

PubMed1992

Distinctive western blot antibody patterns induced by infection of mice with individual strains of the Mycobacterium avium complex.

Systemic infection of mice with organisms of the Mycobacterium avium complex (MAC) induced antibody responses, characteristic for each of the three tested individual strains. The influence of host genetic factors was reflected up to 3 months after infection by the finding of generally oligobanded and multibanded Western blot patterns in C57B1/6 and BALB/c mice, respectively. Nevertheless, more bands developed at 6 months in C57BL/6 mice. The response to three antigens of 18,000, 38,000 and 24,000 MW was analysed in greater detail. Antibodies to a protease-resistant 18,000 MW band produced only by BALB/c mice were either strain specific, following infection with M. avium, strain Maa-B2, or cross-reactive within MAC, following infection with M. avium strain Maa-A6 and M. paratuberculosis, strain Map-203. Another protease-resistant antigen of 38,000 MW was immunogenic only in Maa-B2 infected mice. This constituent was found to be related to the protease-sensitive antigen of corresponding molecular weight from M. tuberculosis. Two 24,000 MW proteins of M. paratuberculosis were separated by two-dimensional gel electrophoresis: antibodies to the anodic band were induced by Map-203 infection, whilst the cathodic band was revealed by heteroclitic antibodies from Maa-B2-infected mice. The latter antigen is apparently expressed during in vivo replication, but not during in vitro culture of Maa-B2 bacteria. We generally conclude, that the selective antibody patterns after live infection, could be attributed to differences in the release of native antigens within mycobacterial lesions. In view of a high degree of species specificity, some of the immunogenic constituents identified may also be useful for serodiagnostic application.

Animals↗

PubMed1993

In-vitro evaluation of clarithromycin, temafloxacin, and ethambutol in combination against Mycobacterium avium complex.

The in-vitro activity of clarithromycin, temafloxacin, and ethambutol were assessed by MIC, FIC and intra-macrophage killing determinations alone and in various combinations against ten pigmented and ten non-pigmented strains of Mycobacterium avium complex bacteria. Alone, either clarithromycin or temafloxacin were found to be active against M. avium, but the best results were obtained from combinations of drugs. Clarithromycin and temafloxacin together were found to have an additive effect against two of ten pigmented variants and one of ten non-pigmented variants. Clarithromycin and ethambutol demonstrated a synergistic effect against two pigmented and one non-pigmented strain, and an additive effect against five and three pigmented and non-pigmented strains, respectively. For temafloxacin and ethambutol, additive effects were observed in four and two pigmented and non-pigmented strains, respectively. In cultures of macrophages both clarithromycin and temafloxacin alone reduced the numbers of bacteria growing intracellularly after six days, but the most effective bactericidal combination was clarithromycin, temafloxacin, and ethambutol together.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Evaluation of new anti-infective drugs for the treatment and prevention of infections caused by the Mycobacterium avium complex. Infectious Diseases Society of America and the Food and Drug Administration.

The bacteria of the Mycobacterium avium complex are ubiquitous; thus it is often difficult to distinguish environmental contamination from colonization or infection. Patients with either pulmonary or disseminated infection may be enrolled in clinical trials. Disseminated disease occurs mostly in patients infected with the human immunodeficiency virus. In general, a randomized, active-control, double-blinded clinical trial is preferred; there should at least be a blinded evaluator. With regard to immunosuppressed populations, new antimycobacterial drugs need to be evaluated not only for the treatment but also for the prevention of disease. For trials of prophylaxis a placebo-controlled design is ethical until a drug is proven effective; then the use of an active-control regimen is appropriate. Since no regimen has been approved by the U.S. Food and Drug Administration for treatment or prevention of disease caused by the M. avium complex, demonstration of the superiority of the study regimen to the control regimen should be the objective of the clinical trial.

Anti-Bacterial Agents↗

PubMed2006

Disseminated Mycobacterium avium complex infection in an immunocompetent pregnant woman.

BACKGROUND: Disseminated mycobacterium avium complex (MAC) occurs mainly in immunocompromised hosts, which is associated with abnormal cellular immunity. CASE PRESENTATION: A 26-year-old pregnant woman presented with fever and general weakness. Miliary lung nodules were noted on chest X-ray. Under the impression of miliary tuberculosis, anti-tuberculosis medication was administered. However, the patient was not improved. Further work-up demonstrated MAC in the sputum and placenta. The patient was treated successfully with clarithromycin-based combination regimen. CONCLUSION: This appears to be the first case of disseminated MAC in an otherwise healthy pregnant woman. Clinicians should be alert for the diagnosis of MAC infection in diverse clinical conditions.

Adult↗

PubMed1997

Intrathoracic Mycobacterium avium complex infection in immunocompetent children: case report and review.

Mycobacterium avium complex (MAC) infection is a rarely recognized cause of intrathoracic infection in immunocompetent children. The incidence of this disease is unknown but is likely underestimated among children in whom MAC infection is not usually considered. An increase in the number of cases of MAC infection in adults has been noted since the late 1970s. The number of these cases in children with AIDS has also increased. There are currently no guidelines for the treatment of these children. We describe a previously healthy 14-month-old boy with a mediastinal mass for whom tuberculosis was initially diagnosed; subsequently, biopsy-proven infection with MAC was demonstrated. He received no specific therapy after surgical excision of his intrathoracic mass and has done well since. We reviewed eight additional cases of intrathoracic nontuberculous mycobacteria infection in children that were reported from 1979 to 1994 and found excellent outcomes for seven immunocompetent children who received diverse methods of treatment.

Female↗

PubMed2000

The role of Mycobacterium avium complex fibronectin attachment protein in adherence to the human respiratory mucosa.

Mycobacterium avium complex (MAC) are opportunistic respiratory pathogens that infect non-immunocompromised patients with established lung disease, although they can also cause primary infections. The ability to bind fibronectin is conserved among many mycobacterial species. We have investigated the adherence of a sputum isolate of MAC to the mucosa of organ cultures constructed with human tissue and the contribution of M. avium fibronectin attachment protein (FAP) to the process. MAC adhered to fibrous, but not globular mucus, and to extracellular matrix (ECM) in areas of epithelial damage, but not to intact extruded cells and collagen fibres. Bacteria occasionally adhered to healthy unciliated epithelium and to cells that had degenerated exposing their contents, but never to ciliated cells. The results obtained with different respiratory tissues were similar. Two ATCC strains of MAC gave similar results. There was a significant reduction (P < 0.05) in the number of bacteria adhering to ECM after preincubation of bacteria with fibronectin and after preincubation of the tissue with M. avium FAP in a concentration-dependant manner. The number of bacteria adhering to fibrous mucus was unchanged. Immunogold labelling demonstrated fibronectin in ECM as well as in other areas of epithelial damage, but only ECM bound FAP. A Mycobacterium smegmatis strain had the same pattern of adherence to the mucosa as MAC. When the FAP gene was deleted, the strain demonstrated reduced adherence to ECM, and adherence was restored when the strain was transfected with an M. avium FAP expression construct. We conclude that MAC adheres to ECM in areas of epithelial damage via FAP and to mucus with a fibrous appearance via another adhesin. Epithelial damage exposing ECM and poor mucus clearance will predispose to MAC airway infection.

Adenoids↗

PubMed1998

Adjunctive corticosteroid therapy for patients whose treatment for disseminated Mycobacterium avium complex infection has failed.

Patients with AIDS and disseminated Mycobacterium avium complex (MAC) infection can have progressive disease despite combination antimycobacterial therapy. Our goal was to determine the utility of corticosteroids as adjunctive therapy for AIDS patients with disseminated MAC infection and refractory symptoms despite combination antimycobacterial therapy. We retrospectively reviewed 12 consecutive patients whose therapy for MAC infection clinically failed and who subsequently received low-dose oral corticosteroids in addition to continued combination antimycobacterial therapy. With the addition of corticosteroids, 11 of 12 patients experienced a rapid improvement in symptoms, with diminished or resolved fevers and night sweats, and an increased sense of well-being and energy. Ten of 12 patients gained weight; the differences between weights before and after steroid therapy were statistically significant (P = .003, paired Student's t-test), and the weights achieved were similar to baseline weights prior to the development of MAC infection (P = .2). Mean survival after diagnosis of MAC infection was 17.5 months. New opportunistic processes developed in seven patients during corticosteroid therapy. However, given the severely immunocompromised status of these patients, it was not possible to attribute the development of new opportunistic processes directly to corticosteroid therapy.

AIDS-Related Opportunistic Infections↗

PubMed2000

Drug-Drug interactions of clinical significance in the treatment of patients with Mycobacterium avium complex disease.

Therapeutic and prophylactic regimens directed specifically against Mycobacterium avium complex (MAC) are increasingly being used in patients infected with the human immunodeficiency virus (HIV). Several of the drugs used in the management of MAC have been associated with significant drug interactions involving the cytochrome P450 (CYP) enzyme system. This enzyme system is also highly influenced by other drugs used in the management of patients with HIV, particularly the protease inhibitors, non-nucleoside reverse transcriptase inhibitors (NNRTIs) and azole antifungals. This article reviews the published concentrations or subtherapeutic concentrations of other drugs have been described. In particular, concurrent use of rifabutin with clarithromycin or fluconazole has resulted in increased concentrations of rifabutin and an accompanying increase in the incidence of rifabutin toxicities, including uveitis and leucopenia. Similar results have been seen when rifabutin is combined with protease inhibitors or delavirdine. The macrolides, clarithromycin and azithromycin, have also been associated with significant drug interactions. Clarithromycin has a higher affinity for CYP than azithromycin and, thus, is more frequently associated with clinically significant drug interactions. Clarithromycin is an inhibitor of CYP and may result in toxic concentrations of other drugs metabolised by this enzyme system. Such interactions have been described with rifabutin and the statin lipid-lowering agents. In addition, nevirapine and efavirenz have been shown to significantly reduce clarithromycin concentrations, whereas the protease inhibitors and delavirdine may increase clarithromycin concentrations. Other drugs used in the management of patients with MAC are not metabolised by CYP and thus have a lower incidence of interactions, although the absorption of ciprofloxacin may be impaired when it is given with products containing multivalent cations, such as didanosine. However, clinicians must remain vigilant for drug interactions when reviewing a patient's medication profile, keeping in mind both interactions that have been described in the literature and those that may be predicted based upon known pharmacokinetic profiles.

Azithromycin↗

PubMed1998

Use of IS901 and IS1245 in RFLP typing of Mycobacterium avium complex: relatedness among serovar reference strains, human and animal isolates.

SETTING: Mycobacterium avium complex (MAC) includes major acquired immune deficiency syndrome (AIDS)-associated pathogens. Formerly, MAC serotyping was used for epidemiological purposes. Recently, restriction fragment length polymorphism (RFLP) typing has become available. OBJECTIVE: Examination of the usefulness of insertion sequence IS1245 in RFLP typing of MAC isolates and the association with IS901 RFLP. DESIGN: Ninety-four serovar reference strains were compared with 144 clinical and animal MAC isolates in RFLP typing. RESULTS: All but four strains containing M. avium-specific-rRNA possessed IS1245. Most human isolates showed polymorphic multiband IS1245 patterns, which were associated with serovars 4, 6 and 8. Sequential clinical isolates obtained at up to five years' distance displayed indistinguishable/closely related patterns. Eleven M. paratuberculosis isolates showed indistinguishable six-band patterns. All 29 MAC isolates from 23 bird species, 7/23 from mammals and 1/81 clinical isolates showed an IS1245 three-band pattern, associated with serovars 1, 2 and 3. All these IS1245 'bird' type strains showed closely related IS901 RFLPs. Only three IS1245 'non-bird' type strains contained IS901, but exhibited completely different RFLP patterns. CONCLUSION: IS1245-RFLP typing is useful for the classification of M. avium and epidemiology of most human isolates. The highly conserved IS901 and IS1245 RFLPs among 'bird' type isolates provide proof that these strains constitute a separate taxon within the MAC.

Animals↗