Treatment of disseminated Mycobacterium avium complex infection in AIDS with amikacin, ethambutol, rifampin, and ciprofloxacin. California Collaborative Treatment Group

The role of amikacin in the treatment of nontuberculous mycobacterial disease

Introduction: Guidelines recommend the use of amikacin in the treatment of nontuberculous mycobacterial (NTM) disease. The authors have evaluated the evidence for the position of amikacin in NTM disease treatment.Areas covered: The authors performed a literature search for original research on amikacin in NTM disease, including its mechanism of action, emergence of resistance, pre-clinical and clinical investigations.Expert opinion: Amikacin shows moderate in vitro activity against the clinically most relevant NTM species (M. avium complex and M. abscessus). It is synergistic with ethambutol, clofazimine, and macrolides and these combinations are effective in animal models. Liposomal encapsulation increases amikacin efficacy. Clinically, the recommended dose of 15 mg/kg intravenous amikacin does not lead to PK/PD target attainment in all patients and a positive impact on long-term treatment outcomes remains unproven in both M. avium complex and M. abscessus disease. Adding the amikacin liposome inhalation suspension did prove to be effective in short and long term in patients not responding to recommended treatment for M. avium complex pulmonary disease. Its optimal use in M. avium complex and M. abscessus pulmonary disease warrants further evaluation.

A Rare Case of Disseminated Mycobacterium avium-intracellulare Presenting as Proctitis

Mycobacterium avium intracellulare (MAI) infections are common in Human Immuno-deficiency Virus (HIV) positive patients. MAI infection can have localized or disseminated presentation, patients with low CD4 count presenting with disseminated infection. Fever, abdominal pain, diarrhea, and weight loss are generally the presenting symptoms of disseminated MAI. We present a rare case of a patient with HIV and low CD4 count presenting with proctitis as manifestation of disseminated MAI infection. A 25 year-old-man with HIV came to the emergency room (ER) with complaints of intermittent rectal bleeding for two months. His CD4 count was less than 20 cells/µL. He was MSM (men having sex with men) and has receptive anal intercourse with men. His stool work-up was unrevealing for infectious etiology. Swabs for gonorrhea and chlamydia were negative. Colonoscopy revealed erythematous, congested, friable rectal mucosa with two superficial ulcers. Biopsies of the ulcer were positive for acid fast staining bacteria and the culture grew MAI. His blood culture was negative for growth of acid-fast bacteria (AFB). However, liver biopsy performed for elevated alkaline phosphatase of 958 units/L revealed noncaseating granuloma. Gastro-duodenoscopy with duodenal biopsy did not reveal any mucosal abnormality. He was managed as with disseminated MAI infection using clarithromycin, ethambutol, and rifabutin in addition to HAART therapy. Interval Colonoscopy in 20 months showed resolution of rectal ulcer. The gut is often involved in patients with disseminated MAI infection, with the duodenum being the most common site. MAI infection should be suspected as possible etiology for proctitis in HIV positive patient with low CD4 count, as proctitis, though infrequent can be the sole presentation for disseminated MAI infection in patients with HIV and low CD4 count.

Effective Treatment of Mycobacterium avium subsp. hominissuis and Mycobacterium abscessus Species Infections in Macrophages, Biofilm, and Mice by Using Liposomal Ciprofloxacin

Nontuberculous mycobacteria (NTM) affect an increasing number of individuals worldwide. Infection with these organisms is more common in patients with chronic lung conditions, and treatment is challenging. Quinolones, such as ciprofloxacin, have been used to treat patients, but the results have not been encouraging. In this report, we evaluate novel formulations of liposome-encapsulated ciprofloxacin (liposomal ciprofloxacin) in vitro and in vivo Its efficacy against Mycobacterium avium and Mycobacterium abscessus was examined in macrophages, in biofilms, and in vivo using intranasal instillation mouse models. Liposomal ciprofloxacin was significantly more active than free ciprofloxacin against both pathogens in macrophages and biofilms. When evaluated in vivo, treatment with the liposomal ciprofloxacin formulations was associated with significant decreases in the bacterial loads in the lungs of animals infected with M. avium and M. abscessus In summary, topical delivery of liposomal ciprofloxacin in the lung at concentrations greater than those achieved in the serum can be effective in the treatment of NTM, and further evaluation is warranted.

Mycobacterium avium Complex Disease

Despite the ubiqitous nature of Mycobacterium avium complex (MAC) organisms in the environment, relatively few of those who are infected develop disease. Thus, some degree of susceptibility due to either underlying lung disease or immunosuppression is required. The frequency of pulmonary MAC disease is increasing in many areas, and the exact reasons are unknown. Isolation of MAC from a respiratory specimen does not necessarily mean that treatment is required, as the decision to treatment requires the synthesis of clinical, radiographic, and microbiologic information as well as a weighing of the risks and benefits for the individual patient. Successful treatment requires a multipronged approach that includes antibiotics, aggressive pulmonary hygiene, and sometimes resection of the diseased lung. A combination of azithromycin, rifampin, and ethambutol administered three times weekly is recommend for nodular bronchiectatic disease, whereas the same regimen may be used for cavitary disease but administered daily and often with inclusion of a parenteral aminoglycoside. Disseminated MAC (DMAC) is almost exclusively seen in patients with late-stage AIDS and can be treated with a macrolide in combination with ethambutol, with or without rifabutin: the most important intervention in this setting is to gain HIV control with the use of potent antiretroviral therapy. Treatment outcomes for many patients with MAC disease remain suboptimal, so new drugs and treatment regimens are greatly needed. Given the high rate of reinfection after cure, one of the greatest needs is a better understanding of where infection occurs and how this can be prevented.

EDP-420, a bicyclolide (bridged bicyclic macrolide), is active against Mycobacterium avium

Infection caused by Mycobacterium avium complex (MAC) is common in patients with immunosuppression, such as AIDS, and deficiencies of gamma interferon and interleukin-12, as well as patients with chronic lung diseases. Treatment of MAC disease is limited since few drugs show in vivo activity. We tested a new bridged bicyclic macrolide, EDP-420, against MAC in vitro and in beige mice. EDP-420 was inhibitory in vitro at a concentration ranging from 2 to 8 microg/ml (MIC(50) of 4 microg/ml and MIC(90) of 8 microg/ml). In macrophages, EDP-420 was inhibitory at 0.5 microg/ml, suggesting that the drug concentrates intracellularly. Mice infected with macrolide-susceptible MAC strain 101 were given 100 mg of EDP-420/kg of body weight daily for 4 weeks and showed a significant reduction in the number of bacteria in both liver and spleen which was greater than the reduction observed with clarithromycin treatment at the same dose (P < 0.05). However, macrolide-resistant MAC 101 did not respond to EDP-420 treatment. A combination of EDP-420 with mefloquine was shown to be indifferent; mefloquine alone was active against macrolide-resistant MAC. The frequency of resistance to EDP-420 in MAC 101 was 10(-9), which is significantly less than the emergence of resistance to clarithromycin, approximately 10(-7) (P < 0.05). Further evaluation of EDP-420 in the treatment of MAC disease is warranted.

Mycobacterium avium complex in patients with HIV infection in the era of highly active antiretroviral therapy

Disseminated Mycobacterium avium complex (MAC) infection is a common complication of late-stage HIV-1 infection. Since the advent of highly active antiretroviral therapy (HAART), the rate of MAC infection has declined substantially, but patients with low CD4 cell counts remain at risk. Among patients in the Johns Hopkins cohort with advanced HIV disease, the proportion developing MAC has fallen from 16% before 1996 to 4% after 1996, with a current rate of less than 1% per year. Factors associated with developing MAC include younger age, no use of HAART, and enrollment before 1996. Prophylaxis with azithromycin or clarithromycin is recommended for all patients with CD4 counts less than 50 cells/mL. Optimum treatment for disseminated MAC includes clarithromycin and ethambutol, and another investigation suggests that the addition of rifabutin might reduce mortality. Both prophylaxis and treatment of disseminated MAC can be discontinued in patients who have responded to HAART, and specific guidelines for withdrawing treatment have been published. Although HAART has altered the frequency and outcome of MAC infection, it remains an important complication of AIDS.

Antimicrobial activities of clarithromycin, gatifloxacin and sitafloxacin, in combination with various antimycobacterial drugs against extracellular and intramacrophage Mycobacterium avium complex

We studied the activities of clarithromycin and fluoroquinolones (gatifloxacin, sitafloxacin, levofloxacin) in combination with other antimycobacterial drugs against extracellular and intramacrophage Mycobacterium avium complex (MAC). Clarithromycin potentiated the activities of rifampicin and rifalazil against both extracellular and intramacrophage MAC. In contrast, all the test quinolones exhibited antagonistic effects against extracellular MAC when combined with either clarithromycin or rifamycins. Such an antagonism was not observed for the activity of these combinations against intramacrophage MAC. Combined effects were observed with combinations of these fluoroquinolones with either ethambutol or streptomycin. Similar profiles were seen for the activities of two-drug combinations of clarithromycin or fluoroquinolones with other drugs against intramacrophage MAC isolated from pulmonary and disseminated MAC infections.

Salivary and urinary excretion and plasma-saliva concentration ratios of isoniazid in the presence of Co-administered ciprofloxacin

Salivary and urinary excretion and plasma-saliva concentration ratios of isoniazid (INH) in the absence and presence of ciprofloxacin (CP) were investigated in healthy female volunteers. Results obtained indicated an absorption form of interaction between INH and CP. This led to delay in gastric emptying and onset of absorption of INH in the upper part of the gastrointestinal tract, resulting in a corresponding delay in the onset of salivary and urinary excretion of the drugs. There was a 1-hour reduction in the time to attain peak saliva concentration of INH (tmax), an insignificant difference in peak saliva concentration (Cmax), and a significant (P = 0.05) increase in AUC(0-24h) of INH in the presence of CP. Cumulative amount of INH excreted in the urine increased approximately 38% in the presence of CP. The calculated plasma-saliva concentration ratios of INH were reduced in the presence of CP and were slightly lower than the experimental values. This indicates increased amount of the drug secreted into saliva in the presence of CP and possible buccal partitioning of the drug. Overall, results of the current study indicate that CP delayed the onset but not the extent of INH absorption. Therefore, concurrent administration of the two drugs was considered relatively safe, and the absorption interaction that may have occurred may not be of reasonable clinical consequence.

Infections of the liver in HIV-infected patients

The liver is a common site of pathology in HIV-infected patients. In patients with controlled HIV and minimal immunosuppression, infection with hepatitis viruses is common owing to the risk factors of sexual transmission or parenteral drug use. In patients with AIDS, the liver is a common site of lymphohematogenous dissemination of several infectious pathogens. A thorough diagnostic approach leads to a diagnosis of most hepatobiliary processes. The therapeutic nihilism that has surrounded hepatic disease, including viral hepatitis, is unwarranted, because treatment of the underlying HIV and the hepatic process may improve the quality of life and longevity of these patients.

A retrospective study of the addition of ciprofloxacin to clarithromycin and ethambutol in the treatment of disseminated Mycobacterium avium complex infection

Disseminated Mycobacterium avium complex (DMAC) infection is associated with increased morbidity and mortality in HIV-infected individuals. The combination antibiotic regimens containing clarithromycin can decrease symptoms and improve survival in patients with DMAC, however, optimal therapy remains to be defined. Quinolones have been widely used in the treatment of DMAC but their utility has not been established. A retrospective cohort study of DMAC infection was established in a metropolitan hospital providing comprehensive care to over 3000 HIV-infected individuals. Medical records of patients with DMAC diagnosed at the Parkland Memorial Hospital from 1991 to 1994 were reviewed for therapeutic regimens for DMAC, concomitant therapy for HIV and Pneumocystis carinii prophylaxis and date of death. Subjects were included if they were treated with clarithromycin and ethambutol. Cases were defined as those patients who received more than 30 days of ciprofloxacin as therapy for DMAC in addition to the other drugs that they received. The primary endpoint was the time to death from the data of DMAC diagnosis. Covariates effecting survival were analysed through the Cox proportional hazards model. Eighty-nine subjects with DMAC who were treated with clarithromycin and ethambutol were identified. Fifty-eight received ciprofloxacin in addition to clarithromycin and ethambutol. The time to death was significantly better in those subjects who were treated with ciprofloxacin than those who were not (489 days vs 281 days, P=0.01). The sole significant predictor of improved survival on Cox proportional hazards model was ciprofloxacin therapy. Subjects treated with combination of clarithromycin, ethambutol and ciprofloxacin had improved survival over those treated with clarithromycin and ethambutol alone.

Efficacy and safety of an intravenous induction therapy for treatment of disseminated Mycobacterium avium complex infection in AIDS patients: a pilot study

Monotherapy with macrolides for the treatment of disseminated Mycobacterium avium complex (MAC) bacteraemia leads to drug resistance and relapse of bacteraemia. Gastrointestinal intolerance is a common reason for treatment withdrawal of multidrug regimens. We have assessed the efficacy and safety of initial parenteral therapy together with a macrolide, for disseminated MAC infection, defined as two positive blood cultures, in AIDS patients. Patients received a daily infusion of amikacin 15 mg/kg + ethambutol 20 mg/kg + ciprofloxacin 400 mg/day, for 1 month, together with a macrolide by oral route. Fifteen patients were included and 13 (86%) achieved negative culture before the end of parenteral therapy.

The aminoglycosides

Despite the introduction of newer, less toxic antimicrobial agents, the aminoglycosides continue to serve a useful role in the treatment of serious enterococcal, mycobacterial, and gram-negative bacillary infections. Gentamicin, because of its low cost, remains the aminoglycoside of choice in hospitals with low levels of resistance among Enterobacteriaceae and Pseudomonas aeruginosa. Typically, it is administered in combination with beta-lactam antibiotics, but it may also be used as monotherapy for urinary tract infections or tularemia. Amikacin is useful against gentamicin-resistant gram-negative bacilli and also in the treatment of infections caused by susceptible Nocardia and nontuberculous mycobacteria. Streptomycin serves an important role in the treatment of multidrug-resistant tuberculosis and may be useful in the treatment of some gentamicin-resistant enterococcal infections. Despite an alarming increase in aminoglycoside-resistant enterococci, most institutions have noted little change in patterns of resistance among gram-negative bacilli. Although the development of newer, less toxic aminoglycosides is unlikely in the near future, single daily dosing regimens have been proposed as a convenient, cost-effective strategy. In selected patients, this novel approach seems to be as safe and effective as traditional, multidose regimens.

Altered expression profile of the surface glycopeptidolipids in drug-resistant clinical isolates of Mycobacterium avium complex

Members of the Mycobacterium avium complex are the most frequently encountered opportunistic bacterial pathogens among patients in the advanced stage of AIDS. Two clinical isolates of the same strain, numbers 397 and 417, were obtained from an AIDS patient with disseminated M. avium complex infection before and after treatment with a regimen of clarithromycin and ethambutol. To identify the biochemical consequence of drug treatment, the expression and chemical composition of their major cell wall constituents, the arabinogalactan, lipoarabinomannan, and the surface glycopeptidolipids (GPL), were critically examined. Through thin layer chromatography, mass spectrometry, and chemical analysis, it was found that the GPL expression profiles differ significantly in that several apolar GPLs were overexpressed in the clinically resistant 417 isolate at the expense of the serotype 1 polar GPL, which was the single predominant band in the ethambutol-susceptible 397 isolate. Thus, instead of additional rhamnosylation on the 6-deoxytalose (6-dTal) appendage to give the serotype 1-specific disaccharide hapten, the accumulation of this nonextended apolar GPL probably provided more precursor substrate available for further nonsaccharide substitutions including a higher degree of O-methylation to give 3-O-Me-6-dTal and the unusual 4-O-sulfation on 6-dTal. Further data showed that this alteration effectively neutralized ethambutol, which is known to inhibit arabinan synthesis. Thus, in contrast with derived Emb-resistant mutants of Mycobacterium smegmatis or Mycobacterium tuberculosis, which are devoid of a surface GPL layer, the lipoarabinomannan from resistant 417 isolate grown in the presence of this drug was not apparently truncated.

Postantibiotic effects of rifampin, amikacin, clarithromycin and ethambutol used alone or in various two-, three- and four-drug combinations against Mycobacterium avium

The postantibiotic effects (PAEs) of rifampin, amikacin, clarithromycin, and ethambutol were determined radiometrically against five AIDS-associated isolates of Mycobacterium avium. and were found to be 20.8+/-3.4. 18.4+/-2.5, 11.8+/-1.7. and 2.4+/-0.9 h, respectively. Various two-, three- or four-drug combinations were also screened: the PAEs for a two-drug combination were generally longer than individual drugs (mean PAE of 13.8+/-1.5 to 29.2+/-7.4 h instead of 2.4+/-0.9 to 18.4+/-2.5 h for single drugs). The addition of a third drug further increased the mean PAE to a range of 21.0+/-2.6 to 32.4+/-6.1 h. Both rifampin+clarithromycin and rifampin+amikacin were the most potent two-drug combinations resulting in longer PAEs than individual drugs, whereas rifampin+amikacin+clarithromycin was the most potent three-drug combination. Parallel viable count determinations showed a good correlation between the PAE results obtained by the radiometric method or by bacterial viability assessment. These results are useful in planning future clinical investigations to clarify the possible implication of PAE in drug schedule and dosage, a line of information that is urgently needed to guide the drug administration in M. avium-infected AIDS patients, who are presently over-burdened with the administration of too many drugs for HIV-treatment and opportunistic infections.

Treatment and prophylaxis of disseminated Mycobacterium avium complex in HIV-infected individuals

OBJECTIVE

To review the pathophysiology, epidemiology, treatment, and prophylaxis of disseminated Mycobacterium avium complex (MAC) infection in HIV-infected individuals.

DATA SOURCES

A MEDLINE (January 1966-July 1997) and AIDSLINE (January 1980-July 1997) search of basic science articles pertinent to the MAC infection in HIV-infected patients.

STUDY SELECTION AND DATA EXTRACTION

All articles were considered for possible inclusion in the review. Pertinent information, as judged by the authors, was selected for discussion.

DATA SYNTHESIS

The organism, epidemiology, and pathophysiology of disseminated MAC are discussed for background. A review of clinical trials for the treatment and prophylaxis of disseminated MAC are presented, along with unresolved issues concerning these topics.

CONCLUSIONS

The incidence of disseminated MAC has increased dramatically with the AIDS epidemic. The infection can lead to increased morbidity and mortality in HIV-infected patients. Treatment regimens for patients with a positive culture for MAC from a sterile site should include two or more drugs, including clarithromycin. Prophylaxis against disseminated MAC should be considered for patients with a CD4 cell count of less than 50/mm3.

Evaluation of a disk diffusion method for determining susceptibility of Mycobacterium avium complex to clarithromycin

We evaluated an agar disk diffusion method for determining the susceptibility of Mycobacterium avium complex to clarithromycin. Isolates were inoculated onto the surface of a Middlebrook 7H11 plate, followed by the application of a 15-microgram clarithromycin disk. Zone sizes were read after 5-7 days of incubation. Zone sizes had a bimodal distribution; 40 isolates (10%) had no zone of inhibition, whereas the zone sizes for the remaining isolates ranged from 11 to 60 mm. Most isolates (37/40) having no zone of inhibition came from patients who had been treated previously with clarithromycin. Fifty-one isolates were also tested for clarithromycin susceptibility using a microdilution broth method. Defining susceptibility as a zone size of > 10 mm, disk diffusion test results agreed with the results by the microdilution broth method for 50 of 51 (98%) isolates tested by both methods. Agar disk diffusion is a promising method for the determination of clarithromycin susceptibility testing for M. avium complex.

Identification and cloning of the Mycobacterium avium folA gene, required for dihydrofolate reductase activity

Dihydrofolate reductase is an essential bacterial enzyme necessary for the maintenance of intracellular folate pools in a biochemically active reduced state. In this report, the Mycobacterium avium folA gene was identified by functional genetic complementation, sequenced, and expressed for the first time. It has an open reading frame of 543 bp with a G + C content of 73%. The translated polypeptide sequence shows 58% identity to the consensus sequence of the conserved regions from eight other bacterial dihydrofolate reductases. Recombinant M. avium dihydrofolate reductase was expressed actively in Escherichia coli, and SDS-PAGE analysis revealed a 20 kDa species, agreeable with that predicted from the polypeptide sequence:

Postantibiotic effect of amikacin, rifampin, sparfloxacin, clofazimine and clarithromycin against Mycobacterium avium

Antimycobacterial drugs acting efficiently against Mycobacterium avium complex have in common low MICs and MBC/MIC ratios. The recently reported clinical efficacy of some of the newer drugs is also clearly linked to their pharmacokinetic properties such as higher serum level and/or intracellular concentrations and half-life. In the present investigation, comparative postantibiotic effects (PAEs) of amikacin, rifampin, sparfloxacin, clofazimine and clarithromycin were investigated. Bacteria were exposed to MIC, MIC x 4 and MIC x 8 concentrations of each drug for 2 h, the drug was removed by centrifugation and cells were thoroughly washed and resuspended in drug-free medium. Growth was compared to control organisms which underwent a similar treatment (but without drugs) and PAEs were assessed using the equation "T-C", where T equals the time required for colony counts to increase by 1 log10 in test samples after antibiotic exposure and C equals the time for 1 log10 growth in control. Our results underlined two distinct patterns concerning PAE: pattern I included drugs for which PAE (in hours) was dose-dependent and varied (for MIC, MIC x 4 and MIC x 8 concentrations) for amikacin (10.3 +/- 1.7, 14.7 +/- 1.9 and 17.7 +/- 4.1), rifampin (28.0 +/- 7.6, 62.0 +/- 18.5 and 71.0 +/- 3.2) and clarithromycin (2.6 +/- 1.0, 15.0 +/- 4.0 and 22.0 +/- 4.0), whereas pattern II included drugs with a stable PAE, relatively independent of the drug concentrations: sparfloxacin (11.0 +/- 2.5, 12.3 +/- 6.4 and 13.0 +/- 2.1) and clofazimine (26.0 +/- 2.8, 28.8 +/- 2.5 and 27.3 +/- 1.3). These results may be useful for guidance in scheduling of drug administration in M. avium-infected AIDS patients overburdened with too many drugs given for various opportunistic infections.

Prophylaxis for disseminated Mycobacterium avium complex (MAC) infection in patients with AIDS: a cost-effectiveness analysis

OBJECTIVE

To determine the effectiveness and costs of prophylaxis for disseminated Mycobacterium avium complex (MAC) infection in patients with AIDS.

DESIGN

A decision analysis model was constructed to compare rifabutin (300 mg/day), azithromycin (1200 mg/week), and clarithromycin (500 mg twice per day) with no prophylaxis. Sensitivity analysis was done on all model parameters, including initial CD4 count for beginning prophylaxis.

SETTING

The setting was hypothetical for the cost-effectiveness model. Clinical data were taken from published prospective randomized controlled trials.

MAIN OUTCOME MEASURES

Outcomes were measured in terms of projected life expectancy, quality-adjusted life expectancy, direct medical costs, and cost-effectiveness in U.S. dollars per quality-adjusted life-year saved ($/QALY).

RESULTS

For patients with AIDS and those having CD4 counts <75 cells/mm3, azithromycin, clarithromycin, and rifabutin prophylaxis increased lifetime per person MAC-related costs by $994, $2,117, and $2,185 U.S., respectively. Quality-adjusted life expectancy increased from 1.6068 QALYs to between 1.6186 and 1.6255 QALYs. The cost-effectiveness ratios were $58,200, $116,000, and $179,100/QALY saved for azithromycin, clarithromycin, and rifabutin prophylaxis, respectively, each compared with no prophylaxis. Results were most dependent on the annual cost of prophylaxis, the initial CD4 count when starting prophylaxis, and any survival benefit with prophylaxis. For each type of prophylaxis, strategies beginning with CD4 counts <25 or 50 cells/mm3 were substantially more cost-effective than those beginning in patients with higher CD4 counts.

CONCLUSIONS

MAC prophylaxis is likely to cost society an additional $99 to $219 million U.S. per 100,000 patients treated. In the context of Centers for Disease Control and Prevention (CDC) recommendations to use prophylaxis in patients with CD4 counts <75 cells/mm3, azithromycin represents the best value and is most cost-effective when used in patients with CD4 counts <25 cells/mm3.

Diagnosis and treatment of disease caused by nontuberculous mycobacteria. This official statement of the American Thoracic Society was approved by the Board of Directors, March 1997. Medical Section of the American Lung Association

Diagnostic criteria of nontuberculous mycobacterial lung disease in HIV-seropositive and -seronegative hosts. The following criteria apply to symptomatic patients with infiltrate, nodular or cavitary disease, or a high resolution computed tomography scan that shows multifocal bronchiectasis and/or multiple small nodules. A. If three sputum/bronchial wash results are available from the previous 12 mo: 1. three positive cultures with negative AFB smear results or 2. two positive cultures and one positive AFB smear B. If only one bronchial wash is available: 1. positive culture with a 2+, 3+, or 4+ AFB smear or 2+, 3+, or 4+ growth on solid media C. If sputum/bronchial wash evaluations are nondiagnostic or another disease cannot be excluded: 1. transbronchial or lung biopsy yielding a NTM or 2. biopsy showing mycobacterial histopathologic features (granulomatous inflammation and/or AFB) and one or more sputums or bronchial washings are positive for an NTM even in low numbers.

COMMENTS

these criteria fit best with M. avium complex, M. abscessus, and M. kansasii. Too little is known of other NTM to be certain how applicable these criteria will be. At least three respiratory samples should be evaluated from each patient. Other reasonable causes for the disease should be excluded. Expert consultation should be sought when diagnostic difficulties are encountered.

Diagnosis and treatment of hepatic disease in patients with HIV

Liver involvement with opportunistic infections and neoplasms is a well-recognized component of AIDS, affecting most patients. The cause of hepatic disease in these patients may be divided into hepatitis, granulomatous disease, mass lesions, vascular lesions, hepatotoxic drugs, and nonspecific findings. With a rational approach, most patients with AIDS and liver disease can be diagnosed and treated in a cost-effective manner with low morbidity.

Clarithromycin and ethambutol with or without clofazimine for the treatment of bacteremic Mycobacterium avium complex disease in patients with HIV infection

OBJECTIVE

To compare the efficacy of two- and three-drug regimens for treating Mycobacterium avium complex (MAC) bacteremia in patients with AIDS.

DESIGN

Randomized open-label clinical trial.

SETTING

Outpatient HIV specialty centers' clinics.

PATIENTS

A total of 106 adults with AIDS and MAC bacteremia.

INTERVENTIONS

Patients were treated with clarithromycin 500 mg twice daily and ethambutol 800-1,000 mg daily and were randomized to receive clofazimine 100 mg daily or no clofazimine.

MAIN OUTCOME MEASURES

Quantitative blood MAC cultures, symptoms, adverse reactions and survival.

RESULTS

Patients randomly assigned to three drugs had significantly higher baseline colony counts of MAC in blood than patients receiving two drugs. The proportion of patients becoming culture-negative was 65% in the two-drug group and 54% in the three-drug group. The median time to negative culture was 58 days for patients in the two-drug and 63 days for the three-drug group. At the last visit during treatment, the mean reduction in colony forming units/ml of MAC in blood was 1.8 log10 for the two-drug group and 2.3 log10 for the three-drug group. Improvement in fever and night sweats was reported by 87 and 89% of the two-drug patients and 84 and 86% of the three-drug patients. During the study, 38% of two-drug patients and 61% of three-drug patients died (P = 0.032), and time to death was shorter in patients treated with three drugs (P = 0.012). In a multivariate analysis, both assignment to clofazimine and high baseline colony counts of MAC bacteremia were significantly associated with death (P < 0.05).

CONCLUSION

The addition of clofazimine to a regimen of clarithromycin and ethambutol for MAC bacteremia in AIDS patients does not contribute to clinical response and is associated with higher mortality.

Complicated anorectal sepsis

These complex anorectal conditions are difficult to diagnose because clinical features overlap. In general, an aggressive approach is reserved for hidradenitis suppurativa and necrotizing infections. Patients with Crohn's disease, hematologic disorders, or AIDS are often treated more conservatively, but the correct timing and degree of aggressiveness of surgical intervention may considerably improve the overall outcome. The increasing incidence of AIDS and the frequency with which infected patients present to surgical clinics make it imperative that all surgeons have a working knowledge of the conditions associated with this syndrome. Expertise is required not only to diagnose and treat these conditions but also to protect oneself and others from being inadvertently infected with the HIV. A high index of suspicion and constant vigilance permit the successful resolution of many of these challenging problems.

Drug treatment of HIV-related opportunistic infections

The AIDS epidemic has led to the emergence of several disease entities which in the pre-AIDS era were rare or seemingly innocuous. Experience of treating these diseases varies. In some instances, such as Pneumocystis carinii pneumonia, there is an abundance of published literature to direct our course of action. However, for many of these newly recognised diseases our treatment experience is limited. Furthermore, in many instances, well controlled trials evaluating treatment modalities in the AIDS population are lacking. We have identified 13 disease entities (P. carinii pneumonia, toxoplasmosis, cryptococcosis, histoplasmosis, Mycobacterium tuberculosis, Mycobacterium avium complex, cytomegalovirus, coccidioidomycosis, isosporiasis, candidosis, Kaposi's sarcoma, herpes simplex virus, and varicella zoster virus) and have reviewed the current literature with regard to their treatment.

HIV in children

Because children acquire HIV infection differently than adults, this article begins with a discussion of the epidemiology of AIDS in children. This is followed by a discussion of factors related to progression of the disease and survival in pediatric AIDS. A discussion of the pulmonary manifestations in children is followed by a suggested approach to the HIV-infected child with respiratory symptoms.

Spectrum of activity of levofloxacin against nontuberculous mycobacteria and its activity against the Mycobacterium avium complex in combination with ethambutol, rifampin, roxithromycin, amikacin, and clofazimine

The spectrum of activity of levofloxacin was initially determined against 29 strains belonging to 16 species of atypical mycobacteria by measuring radiometric MICs. Levofloxacin MICs were 1 to 2 dilutions lower compared with those obtained for ofloxacin and 8 to 64 dilutions lower compared with those obtained for its D-isomer. Levofloxacin MICs were below its peak level in serum (5.5 micrograms/ml following administration of a single oral dose of 350 mg) for 25 of 29 isolates tested. It possessed MICs below its peak level in serum for M. scrofulaceum, M. szulgai, M. malmoense, M. xenopi, M. marinum, M. kansasii, M. chelonei, M. abcessus, M. fortuitum, and M. peregrinum. Regarding the M. avium complex, the MICs of levofloxacin for 11 clinical isolates (7 from human immunodeficiency virus-positive patients and 4 from human immunodeficiency virus-negative patients) were 1 to 2 dilutions lower than those of ofloxacin. Among 20 isolates belonging to 12 pathogenic mycobacterial species, the MBC/MIC ratios varied from 1 to 4 for levofloxacin and 2 to 4 for ofloxacin. When drug combinations were screened by using the radiometric x/y quotient methodology against five M. avium complex isolates, levofloxacin activity against all five isolates was enhanced by ethambutol and activity against three isolates was enhanced by clofazimine. Screening of three-drug combinations showed that the combination levofloxacin-ethambutol with a third potential anti-M. avium drug (rifampin, roxithromycin, amikacin, or clofazimine) resulted in enhanced activity for all 20 drug combinations screened.

Successful treatment of atypical mycobacterial meningitis by fluoroquinolone

We report a case of restricted meningeal infection by atypical mycobacteria, identified by the polymerase chain reaction, in a non-immunocompromised adult successfully treated by multiple antibiotics including fluoroquinolone. New quinolones should be considered as a therapeutic option for such mycobacterial meningitis.

A comparison of two regimens for the treatment of Mycobacterium avium complex bacteremia in AIDS: rifabutin, ethambutol, and clarithromycin versus rifampin, ethambutol, clofazimine, and ciprofloxacin. Canadian HIV Trials Network Protocol 010 Study Group

BACKGROUND

Bacteremia with the Mycobacterium avium complex is common in patients with the acquired immunodeficiency syndrome (AIDS), but the most effective treatment for this infection remains unclear.

METHODS

We randomly assigned 229 patients with AIDS and M. avium complex bacteremia to receive either rifampin (600 mg daily), ethambutol (approximately 15 mg per kilogram of body weight daily), clofazimine (100 mg daily), and ciprofloxacin (750 mg twice daily) (the four-drug group) or rifabutin (600 mg daily), ethambutol (as above), and clarithromycin (1000 mg twice daily) (the three-drug group). In the three-drug group the dose of rifabutin was reduced by half after 125 patients were randomized, because 24 of 63 patients had uveitis.

RESULTS

Among 187 patients who could be evaluated, blood cultures became negative more often in the three-drug group than in the four-drug group (69 percent vs. 29 percent, P<0.001). Among patients treated for at least four weeks, the bacteremia resolved more frequently in the three-drug group (78 percent vs. 40 percent, P<0.001). In the three-drug group, bacteremia resolved more often with the 600-mg dose of rifabutin than with the 300-mg dose (P=0.025), but the latter regimen was more effective than the four-drug regimen (P<0.05). The median survival was 8.6 months in the three-drug group and 5.2 months in the four-drug group (P = 0.001). The median Karnofsky performance score was higher in the three-drug group than in the four-drug group from week 2 to week 16 (P<0.05). Mild uveitis developed in 3 of the 53 patients receiving the 300-mg dose of rifabutin, an incidence about one quarter that observed with the 600-mg dose (P<0.001).

CONCLUSIONS

In patients with AIDS and M. avium complex bacteremia, treatment with the three-drug regimen of rifabutin, ethambutol, and clarithromycin leads to resolution of the bacteremia more frequently and more rapidly than treatment with rifampin, ethambutol, clofazimine, and ciprofloxacin, and survival rates are better.

Hypersensitivity anaphylactoid reaction to pefloxacin in a patient with AIDS

OBJECTIVE

To report a life-threatening anaphylactoid reaction to oral pefloxacin in a patient with AIDS and to review the pertinent literature.

CASE SUMMARY

A 32-year-old woman with AIDS developed an anaphylactoid reaction following a second exposure to oral pefloxacin. This reaction was characterized by severe hypotension, dizziness, itching, and fever.

DISCUSSION

Fluoroquinolones are broad-spectrum antimicrobial agents. They are used frequently in patients with AIDS for numerous indications, including treatment of Mycobacterium avium complex. Pefloxacin, a broad-spectrum fluoroquinolone, was introduced in France in 1985. Since then, many patients with AIDS have been treated with this drug. Several cases of anaphylactoid reactions to ciprofloxacin have been documented in patients with HIV infection. To our knowledge, this is the first reported case of an anaphylactoid reaction to pefloxacin in a patient with AIDS.

CONCLUSIONS

There is a need for continued vigilance in the reporting of adverse drug reactions in patients with AIDS, especially with new drug. Also, care must be taken in introducing drugs, including fluoroquinolones, to this patient population.

Clinical diagnosis of mycobacterial diseases versus autopsy findings in 350 patients with AIDS

Three-hundred fifty consecutively autopsied AIDS patients in Milan, Italy, were studied to determine the frequencies of clinical and postmortem diagnoses of mycobacterial diseases, to evaluate the clinical histories of those patients with mycobacterial diseases, and to investigate the reasons for nondiagnosis of mycobacterial diseases during life. Seventy-eight patients (22.3%) had mycobacterial diseases. In 64 cases (18.3%) the diagnosis was made antemortem and in 50 (14.2%) at autopsy; there were 36 cases of concordant clinical and postmortem diagnoses. Nontuberculous mycobacterioses (NTM) were diagnosed in 41 patients (20 clinical/postmortem diagnoses, 11 clinical diagnoses, and 10 postmortem diagnoses), extrapulmonary tuberculosis (TB) in 19 patients (7 clinical/postmorten, 8 clinical, 4 postmortem), and pulmonary TB in 18 patients (9 clinical/postmorten, 9 clinical). Patients with a clinical diagnosis of mycobacteriosis but with no pathological evidence of disease at autopsy were considered to have recovered on the basis of negative culture findings and prolonged antimycobacterial treatment. In Italian patients with AIDS, NTM occurs less frequently and TB more frequently than in American AIDS patients. At least some of the patients reported in this study seemed to have recovered from mycobacterial disease after prolonged treatment. The lack of diagnosis during life can be attributed to aspecific symptoms, a rapidly terminal course, and the presence of concomitant opportunistic diseases.

Activities of bay Y 3118, levofloxacin, and ofloxacin alone or in combination with ethambutol against Mycobacterium avium complex in vitro, in human macrophages, and in beige mice

Levofloxacin, ofloxacin, and Bay Y 3118 are new fluoroquinolones with variable in vitro bacteriostatic and bactericidal activities against the Mycobacterium avium complex (MAC). The potential therapeutic activities of these agents both alone and combined with ethambutol were evaluated in a human macrophage test system and in the beige mouse animal test system with MAC strain 101. Bay Y 3118 at a human-equivalent dose of 30 mg/kg/day for 4 weeks caused a significant reduction in mortality compared with that in untreated controls (P = 0.02). Bay Y 3118 also caused significant reductions in the number of MAC organisms in the blood, liver tissue, and spleen tissue compared with those in untreated controls. Levofloxacin at a human-equivalent dose of 200 mg/kg/day was associated with a significant reduction in mortality (10 versus 39%); however, treatment with either levofloxacin or ofloxacin (200 mg/kg/day) did not result in significant reductions in the numbers of MAC organisms in blood, liver, and spleen compared with those in untreated controls. When Bay Y 3118 was combined with ethambutol, there was no enhancement in therapeutic activity except in the spleen in terms of CFU per gram (reductions of 89% compared with the untreated control, 63% compared with Bay Y 3118 alone, and 72.5% compared with ethambutol alone). Levofloxacin in combination with ethambutol was more active than either drug alone in the reduction of organisms in blood, liver, and spleen. Bay Y 3118 was the most active fluoroquinolone for monotherapy of MAC infection in beige mice, and the combination of ethambutol plus either levofloxacin or ofloxacin was at least additive. In summary, this study demonstrates that quinolones, although active, are inhibitory against MAC in vivo and that there is little correlation between the activity of quinolones in vitro and the activity in mice.

In vitro activities of rifabutin, azithromycin, ciprofloxacin, clarithromycin, clofazimine, ethambutol, and amikacin in combinations of two, three, and four drugs against Mycobacterium avium

Multidrug therapy is recommended for treatment of Mycobacterium avium complex (MAC) bacteremia in patients with AIDS. Azithromycin, clarithromycin, rifabutin, ciprofloxacin, ethambutol, clofazimine, and amikacin have all been suggested for use in treating MAC bacteremia, but the most active combinations of these drugs have not been identified, nor has the minimum number of drugs needed for effective therapy been determined. To address the former, the in vitro bactericidal activities of all two-, three-, and four-drug combinations of these seven agents was determined by using 10 blood-derived strains of MAC isolated from patients with AIDS. The activities of the 132 drug combinations were compared by statistical analysis of survival means (analysis of variance) and further evaluated by determining the percentage of strains considered susceptible to each combination. When susceptibility was defined as a decrease in CFU of > or = 2 log10, no two- or three-drug combination and only two four-drug combinations were active against all 10 MAC strains. When a less stringent definition was applied (> or = 1 log10 decrease in CFU), 1 two-drug combinations, 9 three-drug combinations, and 31 four-drug combinations showed activity against all 10 strains. Eighteen selected drug combinations were also tested for intracellular activity in MAC-infected J774 cells. Combinations which contained amikacin as a component were considerably less active against intracellular MAC organisms than against organisms in broth. The opposite result was obtained for the combination of clarithromycin plus clofazimine.

Clarithromycin against Mycobacterium avium complex infections

The turning point in antimicrobial therapy of Mycobacterium avium infections came with the development of two new macrolides, clarithromycin and azithromycin. Controlled clinical trials, the first ever conducted with any agent among patients with M. avium infection, indicated the high efficiency of clarithromycin, in either acquired immune deficiency syndrome (AIDS) patients having a disseminated infection or non-AIDS patients with localized pulmonary disease. Monotherapy with clarithromycin resulted in elimination of bacteremia in almost all patients with disseminated infection, which is inevitably followed by a relapse of bacteremia in patients who survived long enough to reach this event. The strains susceptible to clarithromycin isolated before therapy contained 10(-8) or 10(-9) resistant mutants, and the relapses of bacteremia were caused by multiplication of these pre-existing mutants. Clarithromycin-resistance was associated with a mutation in the 23S rRNA gene. Cross-resistance between clarithromycin and azithromycin was confirmed with laboratory mutants and clinical isolates. At least two methods for determining the susceptibility of the M. avium isolates to clarithromycin are available: one is minimum inhibitory concentration (MIC) determination on Mueller-Hinton agar (pH 7.4) supplemented with 10% Oleic acid-albumin-dextrose catalase, the other is MIC determination in 7H12 broth, also at pH 7.4. The breakpoints for 'susceptible' for these methods are < or = 8.0 micrograms/ml and < or = 2.0 micrograms/ml, respectively. The breakpoints for 'resistant' are > 128 micrograms/ml for the agar method and > 32.0 micrograms/ml for the broth method. The predictability value of MIC determination was confirmed by comparing the test results with the patients' clinical and bacteriological response to therapy. The remaining major problem in the therapy of the M. avium infections is a selection of companion drugs to be used in combination with clarithromycin (or azithromycin) to prevent the emergence of the macrolide-resistance. A number of clinical trials are now in progress to find a solution to this problem.

Cervical lymphadenitis caused by a fastidious mycobacterium closely related to Mycobacterium genavense in an apparently immunocompetent woman: diagnosis by culture-free microbiological methods

Fastidious mycobacteria usually infect immunocompromised hosts (human immunodeficiency virus-infected or otherwise immunosuppressed patients). We here describe severe lymphadenitis, caused by a fastidious mycobacterium closely related to Mycobacterium genavense, in an apparently immunocompetent woman, whose brother had died from an unidentified mycobacterial infection in 1969. A variety of techniques, including inoculation of nude mice, histopathology, electron microscopy, lipid analysis, ATP measurements, and molecular biology, were used to characterize this mycobacterium. All attempts to culture the etiological agent on many different media failed. The organism multiplied only in congenitally athymic nude mice. Although phenotypically similar to M. genavense, the mycobacterium differs from M. genavense by three nucleotides of the 16S rRNA gene sequence. Various antimycobacterial drugs were administered, including gamma interferon, but multiple relapses occurred. Finally, therapy with a combined regimen of clarithromycin, clofazimine, rifabutin, and ethambutol was curative. To our knowledge, this is the first report of lymphadenitis in an apparently immunocompetent patient, caused by a noncultivable Mycobacterium sp. closely related to M. genavense. This study emphasizes the importance of employing a variety of diagnostic approaches such as the inoculation of laboratory animals, histopathology, electron microscopy, lipid analysis, ATP measurements, and molecular biology to characterize novel microorganisms that cannot be cultured in vitro.

Evaluating the quality of life associated with rifabutin prophylaxis for Mycobacterium avium complex in persons with AIDS: combining Q-TWiST and multiattribute utility techniques

Our objective was to evaluate the effect of rifabutin prophylaxis in patients with AIDS and CD4 counts of less than 200 per cubic millimetre using a combination of Q-TWiST (quality-adjusted time without symptoms and toxicity) and multiattribute health utility assessment. The design consisted of a secondary analysis of two previously reported multicentre, randomized, placebo-controlled clinical trials conducted in 78 academic, community and Department of Veterans Affairs HIV centres and private practices. 542 patients with AIDS and CD4 counts of less than 200 per cubic millimetre were assigned to rifabutin 300 mg/day and 562 were assigned to a placebo. A modified Q-TWiST approach was used for comparing treatments based on the occurrence and duration of time with and without severe symptoms and clinical endpoints. Health states were constructed to represent combinations of clinical events experienced by study patients. Five physicians assigned utilities for health states using a six-attribute health classification system. These utilities were used to adjust survival for QOL. The rifabutin and placebo groups were compared using estimated quality-of-life-adjusted days. The incidence of MAC was 9% for the rifabutin group and 18% for the placebo group (p < 0.001). Differences, although not statistically significant, were observed for rates of survival and hospitalization. The rifabutin group experienced less anaemia (p < 0.02), and fever and night sweats (p < 0.02) than the placebo group. Average Q-TWiST days were 325 for the rifabutin group and 309 for the placebo group (p < 0.05). Q-TWiST days were significantly lower for patients with MAC bacteraemia (p < 0.04) and hospitalizations (p < (0.003). Rifabutin prophylaxis resulted in fewer MAC infections and greater quality-of-life-adjusted days of survival compared to no rifabutin. Quality-of-life-adjusted survival, based on a combination of the Q-TWiST and multiattribute health utility index, is a feasible approach for evaluating the outcomes of medical treatment. Future studies should, however, use patient-assigned utility weights to compute Q-TWiST scores, since physician generated utilities may differ significantly from those of patients.

Clarithromycin in the treatment of Mycobacterium avium lung infections in patients without AIDS. Clarithromycin Study Group of France

Mycobacterium avium complex infections, common in patients with AIDS as either pulmonary or disseminated disease, are infrequent in patients without AIDS. Participants were 45 HIV-negative patients with lung disease and positive sputum cultures for M avium; 10 had documented immunocompromise, and 24 had preexisting lung disease. Clarithromycin dosage was 500 to 2,000 mg daily (mean +/- SD = 1,633 +/- 432 mg). The drug was administered either alone (n = 14) or in combination with rifampin (n = 8), aminoglycoside (n = 1), quinolone (n = 10), clofazimine (n = 18), isoniazid (n = 5), ethambutol (n = 9), pyrazinamide (n = 1), or minocycline (n = 6). At 3 months, 36 patients among 39 bacteriologically assessed had negative sputum cultures, 3 had positive culture, 3 were dead, and 3 discontinued treatment. At the end of treatment, 32 patients remained negative, 7 were positive. The success rate was 15 of 22 (64%) in patients previously treated with antimycobacterial drugs for M avium disease and 17 of 23 (74%) in new patients. Adverse effects included mild hearing loss (n = 4), increase in liver enzyme levels (n = 5), and gastrointestinal pain (n = 10, two of whom had to stop treatment). Patients stopped treatment after 300 +/- 186 days due to side effects (3), death (4), or the patient's (5) or physician's decision (33). During the follow-up, one patient suffered a relapse with peripheral lymph nodes. A daily dose of 30 mg/kg of clarithromycin in the treatment of M avium infections appears to be effective and safe. Concomitant drug therapy should be assessed for its ability to prevent relapse.

Therapy of Mycobacterium avium complex infections in beige mice with streptomycin encapsulated in sterically stabilized liposomes

Mycobacterium avium complex (MAC) causes serious opportunistic infections in AIDS patients. Previous studies with MAC-infected beige mice have indicated that weekly administration of liposome-encapsulated streptomycin can reduce significantly the CFU in the liver and spleen. We examined whether streptomycin encapsulated in recently developed sterically stabilized liposomes with prolonged circulation times would have a therapeutic effect in this animal model. Two liposome types with prolonged circulation (polyethyleneglycol-distearoylphosphatidylethanolamine [PEG-DSPE]-distearoylphosphatidylcholine [DSPC]-cholesterol [chol] or phosphatidylinositol [PI]-DSPC-chol) and conventional liposomes (phosphatidylglycerol [PG]-phosphatidylcholine [PC]-chol) encapsulating streptomycin and administered twice weekly were bactericidal to MAC strain 101 in the spleen when the level of infection after treatment was compared with the level of infection before treatment. PI-DSPC-chol and PG-PC-chol liposomes encapsulating streptomycin were bactericidal in the liver. Although PG-PC-chol or PEG-DSPE-DSPE-chol liposomes encapsulating streptomycin were not bactericidal in the lungs, they reduced the level of MAC infection by more than 3 orders of magnitude compared with the level of MAC infection in untreated controls.

French multicenter study involving eight test sites for radiometric determination of activities of 10 antimicrobial agents against Mycobacterium avium complex

The radiometric BACTEC 460-TB methodology has filled an increased need in the screening of a wide range of antimicrobial agents against Mycobacterium avium (MAC) isolates on a patient-to-patient basis. In this context, a multicenter study involving eight test sites across France was performed to determine the MICs of 10 antimicrobial agents for MAC organisms. The aim of the investigation was to compare the in vitro activities of D-cycloserine, ethambutol, ethionamide, rifampin, amikacin, streptomycin, ciprofloxacin, sparfloxacin, clofazimine, and clarithromycin against MAC isolates. All of the test sites received the same clinical isolates of MAC, and the MICs were determined by a common protocol. The overall interlaboratory reproducibility of the MICs within +/- 1 dilution of the modal MICs varied from 79.70 to 100% (mean, 95.2% +/- 2.1%), whereas overall agreement of the MICs among the test sites varied from a mean of 91% +/- 4.1% to a mean of 98 +/- 1.3%. We confirmed that the proposed methodology is easy, accurate, and sufficiently reproducible to be used routinely in a clinical laboratory. Despite variations in the MICs of the same drug among strains, no link between the origin of MAC isolates (from human immunodeficiency virus-positive or -negative patients) and their drug susceptibilities was established. On the basis of the MICs that inhibited 50 and 90% of isolates tested for the drugs used, clarithromycin, clofazimine, ethambutol, and streptomycin were the most uniformly active against MAC; this was followed by amikacin, rifampin, and sparfloxacin. On the other hand, ciprofloxacin, D-cycloserine, and ethionamide showed only marginal in vitro activities.