Cerebral toxoplasmosis and co-trimoxazole prophylaxis

Meta-analysis of prevention and treatment of toxoplasmic encephalitis in HIV-infected patients

Toxoplasmic encephalitis (TE) is one of the most common central nervous system (CNS) opportunistic infections in HIV-infected patients. It can be prevented and treated through drug regimen. However, drugs have serious adverse effects sometimes. The purpose of this review is to determine the most effective therapy for TE in HIV-infected patients. Different primary prophylaxis and treatment regimens have been compared with regard to episodes of TE, clinical response, morbidity, and serious adverse events. In September 2012, we searched PubMed, Google Scholar, EMBASE, and CENTRAL (the Cochrane Central Register of Controlled Trials) database for randomized and quasi-randomized controlled trials of any drug regimen for primary prophylaxis and treatment of TE in HIV-infected patients. We independently extracted data and assessed eligibility and risk of bias using a standardized data collection form, and resolved any disagreement through discussion. We combined dichotomous outcomes using odds ratio (OR), presenting with 95% confidence interval (CI). Eleven trials were found to meet the inclusion criteria. Six trials compared trimethoprim-sulfamethoxazole (TMP-SMX) with dapsone-pyrimethamine (D-P) were analyzed together for the outcome of episodes of TE, morbidity, and serious adverse events. The two treatment arms did not differ for episodes of TE (OR=0.98; 95% CI: 0.48-2.00). Compared with D-P, TMP-SMX showed a beneficial trend in terms of mortality despite a lack of statistical significance (OR=0.75; 95% CI: 0.53-1.06). However, TMP-SMX is still associated with substantial toxicity and intolerance (OR=1.47; 95% CI: 0.91-2.38). Three trials compared pyrimethamine-sulfadiazine (P-S) with pyrimethamine-clindamycin (P-C) were analyzed together for the outcome of clinical response, morbidity, and serious adverse events. Compared with P-C, P-S showed a beneficial trend in terms of clinical response (OR=1.63; 95% CI: 1.05-2.51); P-S also showed a beneficial trend in terms of mortality despite a lack of statistical significance (OR=0.66; 95% CI: 0.37-1.17). However, P-S is still associated with substantial toxicity and intolerance (OR=3.08; 95% CI: 1.82-5.24). Two trials compared P-S with TMP-SMX were analyzed together for the outcome of clinical response, morbidity, and serious adverse events. The two treatment arms did not differ for clinical response (OR=0.90; 95% CI: 0.39-2.06). Compared with TMP-SMX, P-S showed a beneficial trend in terms of mortality despite a lack of statistical significance (OR=0.12; 95% CI: 0.01-1.39). However, P-S is still associated with substantial toxicity and intolerance (OR=2.91; 95% CI: 0.99-8.55). The available evidence fails to identify any one superior regimen for the primary prophylaxis and treatment of TE. The choice of therapy will often be directed by available therapy. Although current evidence does not allow a definitive recommendation, administration of TMP-SMX for primary prophylaxis and treatment of TE in patients with HIV infection is consistent with the available data.

Reactivations of ocular toxoplasmosis after cataract extraction

PURPOSE

To determine the risk of reactivation of ocular toxoplasmosis following cataract extraction.

DESIGN

Retrospective case-control study.

PARTICIPANTS

Out of 154 patients with ocular toxoplasmosis, 14 patients (15 eyes) who had undergone a cataract extraction and 45 age- and sex- matched controls without cataract were selected.

INTERVENTION

A review of the medical records of 14 patients with ocular toxoplasmosis and cataract and 45 control patients with ocular toxoplasmosis but without cataract. The clinical records of the controls and patients were assessed for an identical 4-month period following the date of the cataract extraction in the index patients.

MAIN OUTCOME MEASURES

Development of a new active retinal lesion within 4 months after cataract surgery in patients and age -and sex matched-controls. The presence of risk factors such as sex, congenital or postnatal acquisition of ocular toxoplasmosis, age at first clinical manifestation of ocular toxoplasmosis, total number of attacks per affected eye, type of cataract, age at the time of cataract surgery and the intervals between surgery and first clinical manifestation of ocular toxoplasmosis and between surgery and the last recurrence of ocular toxoplasmosis, as well as the use of antiparasitic medication during surgery, type and complications of surgery and optimal visual acuity before and after cataract surgery.

RESULTS

Reactivations of ocular toxoplasmosis following cataract extraction occurred in 5/14 patients (5/15 eyes), which was higher than the incidence of recurrences in age -and sex-matched controls (p < 0.001). No additional risk factors for the development of recurrences of ocular toxoplasmosis after cataract surgery were found. Incidence of recurrences preceding surgery did not differ between patients and controls.

CONCLUSION

We identified an increased risk of reactivation of ocular toxoplasmosis following cataract extraction which implies that prophylactic treatment with antiparasitic drugs during and after the cataract surgery might be worthwhile for patients at risk of visual loss.

[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.

Treatment regimens for patients with toxoplasmic encephalitis

Toxoplasma gondii is an obligate intracellular parasitic protozoan that infects a variety of warm-blooded animals, including humans. Infection is usually asymptomatic in immunocompetent individuals but may be devastating in immunocompromised individuals such as those with acquired immunodeficiency syndrome (AIDS). Clinical manifestations of infection in immunocompromised patients include the development of encephalitis. It has been estimated that approximately 30% of patients with AIDS who are latently infected will eventually develop toxoplasmic encephalitis. The most common regimen used to treat toxoplasmic encephalitis is a combination of pyrimethamine 50 to 100 mg/d and sulfadiazine 4 to 8 g/d, with or without folinic acid 10 mg/d. This regimen, however, commonly leads to adverse effects or relapses. Other pharmacologic approaches include the use of clindamycin rather than sulfadiazine, the macrolide antibiotics, atovaquone, 5-fluorouracil, trimethoprim/sulfamethoxazole, minocycline or doxycycline, trimetrexate with folinic acid, dapsone, rifabutin, pentamidine, and diclazuril. None of these alternative regimens has been proven to be more effective than the standard pharmacologic therapy. An evolving approach is the use of immunotherapy, such as interleukin-2, -6, and -12; interferon-gamma; and alpha-tumor necrosis factor. Restoring a competent immune system may be the only cure for toxoplasmosis and other opportunistic infections.

Therapeutic approaches for AIDS-related toxoplasmosis

OBJECTIVE

To summarize current knowledge of prophylaxis and treatment of AIDS-related toxoplasmosis.

DATA SOURCES

A MEDLINE search (1985-1994) was used to identify pertinent literature, including reviews.

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

Trimethoprim/sulfamethoxazole (TMP/SMX) appears to be useful for prophylaxis against toxoplasmosis in patients with AIDS. The most effective TMP/SMX dose for prevention of toxoplasmosis needs to be determined. Dapsone in combination with pyrimethamine therapy may be an effective alternative for toxoplasmosis prophylaxis. The most effective regimen for the treatment of AIDS-related toxoplasmosis is the combination therapy of pyrimethamine/sulfadiazine. In patients who cannot tolerate sulfadiazine therapy because of adverse effects or allergy, pyrimethamine with clindamycin therapy may be considered as a second-line alternative. Lifelong suppressive therapy is required after either treatment regimen to prevent relapse. Other newer agents such as azithromycin, clarithromycin, atovaquone, or timetrexate-leucovorin need further studies to confirm their true effectiveness in the treatment of toxoplasmosis.

CONCLUSIONS

TMP/SMX remains a useful agent in prophylaxis against toxoplasmosis. Pyrimethamine/sulfadiazine is the most effective combination in the treatment of acute toxoplasmosis.

Outcome of Toxoplasma gondii mismatches in heart transplant recipients over a period of 8 years

Donor-related infection due to Toxoplasma gondii is a well-recorded complication of cardiac transplantation. In order to assess the efficacy of co-trimoxazole in small doses as prophylaxis for primary Toxoplasma gondii infection in seronegative heart and heart-lung transplant recipients receiving organs from seropositive donors, we reviewed the serostatus and clinical outcome of all such mismatched transplants performed at our unit over a period of 8 years. Of 310 transplants performed between May 1985 and May 1993, donor and recipient serum samples were available for 257 heart and 33 heart-lung transplants. Of these, 13 (4.5%) were toxoplasma mismatches. Post-transplant review serum samples were available for 3 months or longer for nine of the 13 mismatches. The first three patients received co-trimoxazole 480 mg bd orally for 3 months (regimen A) while the remainder received only the standard prophylaxis designed for Pneumocystis carinii i.e., 960 mg bd orally three times per week for 3 months (regimen B). Seroconversion was demonstrated in only one patient (regimen A). Furthermore, none of the mismatched patients developed serious infection compatible with primary toxoplasmosis. We therefore conclude that in centres with a low prevalence of toxoplasma seropositivity, testing of donor and recipient serum for Toxoplasma gondii antibody should be performed only when clinically indicated and, in addition, standard prophylaxis for Pneumocystis carinii may be adequate for preventing primary toxoplasmosis.

Long-term results of monthly inhaled pentamidine as primary prophylaxis of Pneumocystis carinii pneumonia in HIV-infected patients

PURPOSE

To evaluate the long-term efficacy and safety of inhaled pentamidine as primary prophylaxis against Pneumocystis carinii pneumonia (PCP) in patients infected with human immunodeficiency virus (HIV).

PATIENTS

Two hundred thirty-two HIV-infected patients with a CD4 cell count below 20% of the total lymphocyte count were given aerosolized pentamidine once every 4 weeks for more than 3 months. Pentamidine aerosols were administered at the hospital under medical supervision. Prevention of bronchospasm was carried out using inhaled salbutamol.

RESULTS

Mean duration of prophylaxis was 15.9 months. Eleven patients (4.7%; [95% confidence interval 2% to 7.4%]) developed PCP. Probability to remain free of PCP is 95.6% at 12 months, 94% at 18 months, and 88% at 24 months. Mean delay between the onset of the prophylaxis and the occurrence of PCP for the 11 patients was 12.9 months (range: 4 to 26 months). No major side effect was observed, and minor side effects (cough, acute dyspnea) were infrequent.

CONCLUSION

The efficacy and tolerance of aerosolized pentamidine as shown in our study support its use as primary prophylaxis against P. carinii in HIV-infected patients.