Intermittent co-trimoxazole prophylaxis against Pneumocystis carinii pneumonia

A randomized trial of the discontinuation of primary and secondary prophylaxis against Pneumocystis carinii pneumonia after highly active antiretroviral therapy in patients with HIV infection. Grupo de Estudio del SIDA 04/98

BACKGROUND

Prophylaxis against Pneumocystis carinii pneumonia is indicated in patients with human immunodeficiency virus (HIV) infection who have less than 200 CD4 cells per cubic millimeter and in those with a history of P. carinii pneumonia. However, it is not clear whether prophylaxis can be safely discontinued after CD4 cell counts increase in response to highly active antiretroviral therapy.

METHODS

We conducted a randomized trial of the discontinuation of primary or secondary prophylaxis against P. carinii pneumonia in HIV-infected patients with a sustained response to antiviral therapy, defined by a CD4 cell count of 200 or more per cubic millimeter and plasma HIV type 1 (HIV-1) RNA level of less than 5000 copies per milliliter for at least three months. Prophylactic treatment was restarted if the CD4 cell count declined to less than 200 per cubic millimeter.

RESULTS

The 474 patients receiving primary prophylaxis had a median CD4 cell count at entry of 342 per cubic millimeter, and 38 percent had detectable HIV-1 RNA. After a median follow-up period of 20 months (758 person-years), there had been no episodes of P. carinii pneumonia in the 240 patients who discontinued prophylaxis (95 percent confidence interval, 0 to 0.85 episode per 100 person-years). For the 113 patients receiving secondary prophylaxis, the median CD4 cell count at entry was 355 per cubic millimeter, and 24 percent had detectable HIV-1 RNA. After a median follow-up period of 12 months (123 person-years), there had been no episodes of P. carinii pneumonia in the 60 patients who discontinued prophylaxis (95 percent confidence interval, 0 to 4.5 episodes per 100 person-years).

CONCLUSIONS

In HIV-infected patients receiving highly active antiretroviral therapy, primary and secondary prophylaxis against P. carinii pneumonia can be safely discontinued after the CD4 cell count has increased to 200 or more per cubic millimeter for more than three months.

[Epidemiologic characteristics of cerebral toxoplasmosis in 399 HIV-infected patients followed between 1983 and 1994]

OBJECTIVE

To describe the epidemiological characteristics of toxoplasmic encephalitis in HIV-infected patients with a more than 12-year follow-up.

METHODS

From a data base of 1,628 AIDS subjects hospitalized from 1983 to 1994, we studied the epidemiological characteristics of 399 patients with toxoplasmic encephalitis. Diagnosis of toxoplasmic encephalitis was based on the association of central neurological disorders, typical lesions on CT scan or MRI, and favorable outcome under appropriate toxoplasmosis therapy.

RESULTS

Four hundred sixty-four cases of toxoplasmic encephalitis were reported in 399 patients (24.5% of the patients with AIDS). The overall incidence was 20.5 per 100 patients-year. Toxoplasmic encephalitis was the first AIDS defining event in 51% of the cases and revealed HIV infection in 13% of the cases. In the remaining 49%, the mean delay from AIDS diagnosis to toxoplasmic encephalitis was 13 months (range: 1-71 months). At the time of diagnosis, mean CD4 count was 44/mm3 (range: 0-408/mm3). Antibodies to Toxoplasma gondii were found in 97% of the cases. Before the first episode of toxoplasmic encephalitis, 58% of the patients were given antiretroviral therapy (mean: 17.8 months; range: 1-64 months). Of the 399 patients with toxoplasmic encephalitis, 366 (92%) did not receive any primary toxoplasmosis prophylaxis. Among them, 205 (56%) did not receive any drug prophylaxis, and 161 (44%) had Pneumocystis carinii pneumonia prophylaxis alone (aerosolized pentamidine). Thirty-three failures were observed (8%) with cotrimoxazole: 14 cases (3%) were considered to have irregular compliance. Sixty-five relapses were observed in 52 patients. At the end of the study 334 patients had died (84%). The median survival was 11.4 months (95% confidence interval, range: 10.4-12.4 months).

CONCLUSIONS

Toxoplasmic encephalitis incidence has decreased since the introduction of appropriate drug prophylaxis.

Randomized study of sulfamethoxazole-trimethoprim versus aerosolized pentamidine for secondary prophylaxis of Pneumocystis carinii pneumonia in patients with AIDS

In a prospective, randomized open-label trial, the efficacy of sulfamethoxazole-trimethoprim (SMX-TMP) 400/80 mg b.i.d. was compared with the efficacy of aerosolized pentamidine (AP) 60 mg every 2nd week as secondary prophylaxis (SP) against recurrence of Pneumocystis carinii pneumonia (PCP) in AIDS patients. 94 patients participated in the study, 47 in each group. The patients were observed for a mean period of 17.2 months. PCP recurred in the AP group in 8 cases, while 1 relapse occurred in the SMX-TMP group. The one-year cumulative relapse rate was 9.0% (95% CI 0-19%) in the AP group compared with 2.4% (95% CI 0-8%) in the SMX-TMP group (p < 0.05). The odds ratio was 4.2 (95% CI 0.5-39.8) in favour of SMX-TMP. Furthermore, we found a tendency towards a protective effect against toxoplasmosis in the SMX-TMP group, though there was no difference in survival between the two groups. There was no statistical difference in frequency of crossover from one therapy form to the other. Based on these data we recommend SMX-TMP for secondary PCP prophylaxis.

Prospective randomized comparison of toxicity of two prophylactic regimens of cotrimoxazole in leukemic children

Cotrimoxazole is currently used for Pneumocystis carinii pneumonia prophylaxis in leukemic children. The former regimen of continuous administration was recently replaced by intermittent administration. The antifolic activity of cotrimoxazole could theoretically enhance that of methotrexate, also administered to leukemic children. We report on a prospective, randomized study to compare two different regimens--continuous vs. 3 days a week--of cotrimoxazole prophylaxis. The aim of the study was to evaluate the toxicity, assuming that both regimens are equally effective to prevent P. carinii pneumonia. Seventy-seven leukemic children were enrolled; 67 were evaluable, 35 from arm A (continuous), 32 from arm B (intermittent cotrimoxazole administration). The conclusion was that long-term maintenance chemotherapy with antimetabolites produced lower levels of folate but normal levels of vitamin B12 in leukemic children. This pattern did not vary between the continuous and the 3-days-a-week administration of cotrimoxazole prophylaxis. Thus it seems hypothesizable that the antimetabolic activity of methotrexate alone exceeds that of cotrimoxazole.

Trimethoprim-sulfamethoxazole

The antimicrobial combination of trimethoprim and sulfamethoxazole is active in vitro against various gram-positive and gram-negative bacteria. Clinically, it is useful for prophylaxis and treatment of selected infections of the genitourinary, respiratory, and gastrointestinal tracts. Trimethoprim-sulfamethoxazole by itself or in combination with other antimicrobial agents is indicated for most Nocardia asteroides infections and is the antimicrobial agent of choice for Pneumocystis carinii pneumonia. The drug is relatively nontoxic in patients who do not have the acquired immunodeficiency syndrome (AIDS) and is available in both oral and intravenous forms. The native compounds and the metabolites of trimethoprim and sulfamethoxazole are excreted primarily in the urine. When the creatinine clearance is less than 30 ml/min, the dosage of trimethoprim-sulfamethoxazole should be adjusted.

Treatment and prophylaxis of Pneumocystis carinii pneumonia in AIDS patients

Pneumocystis carinii pneumonia (PCP) is seen in people with a defect in cell-mediated immunity. Today the most common cause for this is the Acquired Immunodeficiency Syndrome (AIDS). There have been some remarkable advances recently in the development of new drug regimens to combat this otherwise fatal infection. Although cotrimoxazole (trimethoprim-sulfamethoxazole) is still the drug of first choice it cannot be tolerated by a significant proportion of patients, and therapies such as pentamidine (pentamidine-isethionate) [intravenous or nebulised], dapsone-trimethoprim, eflornithine (DFMO; difluoromethylornithine), trimetrexate, and clindamycin-primaquine are finding therapeutic niches. The major advantage in these other agents is not improved efficacy but different toxicity profiles, enabling therapy to be most appropriately tailored to individual patients' conditions. Although the majority of patients should now survive an attack of PCP, relapses will occur if prophylaxis is not used. There is also the capacity to predict accurately which patients are at risk for this pneumonia and prevent it through the use of chemoprophylaxis. These advances in the treatment and prevention of PCP, together with anti-retroviral therapy, mean that this is an area of AIDS management that has resulted in improved long term survival.