Atovaquone: a new antipneumocystis agent.

The mechanism of action, pharmacokinetics and pharmacodynamics, clinical efficacy, adverse effects, and dosage of atovaquone in the management of mild to moderate Pneumocystis carinii pneumonia (PCP) are reviewed. Atovaquone has a novel mechanism of action that has been hypothesized to result in microbicidal rather than microbistatic activity against Pneumocystis carinii. Absorption of the drug is significantly enhanced by the presence of food, particularly food with a high fat content. In comparative trials, atovaquone was slightly less effective than trimethoprim-sulfamethoxazole and as effective as pentamidine isethionate in treating mild to moderate PCP. Atovaquone is associated with a lower incidence of treatment-limiting adverse reactions than are trimethoprim-sulfamethoxazole and pentamidine isethionate. The most commonly occurring adverse effect in patients receiving atovaquone is rash, and the drug does not appear to cause bone marrow suppression. The FDA-approved dosage regimen for atovaquone in treating mild to moderate PCP is 750 mg (three 250-mg tablets) administered orally three times daily with food for 21 days. Atovaquone may be considered a first-line treatment for patients with the acquired immunodeficiency syndrome who have mild to moderate PCP and have demonstrated an intolerance to trimethoprim-sulfamethoxazole.

Intravenous streptomycin use in a patient infected with high-level, gentamicin-resistant Streptococcus faecalis.

OBJECTIVE: To report a case of intravenous streptomycin sulfate use in a patient infected with high-level, gentamicin-resistant Streptococcus faecalis. CASE SUMMARY: A 37-year-old woman with a history of schizoaffective disorder, diabetes insipidus possibly induced by lithium, chronic renal insufficiency, and anemia presented with a two-day history of decreased responsiveness, decreased verbalization, and tremulousness. Her hospital course was complicated by polymicrobial sepsis (S. faecalis, coagulase-negative staphylococci, Citrobacter diversus, Enterobacter aerogenes, and unidentified gram-negative bacilli #2) requiring vancomycin and gentamicin therapy. Gentamicin was discontinued after two doses because she developed acute-on-chronic renal insufficiency. Subsequent susceptibility data showed the enterococcus to be highly resistant to gentamicin. The patient deteriorated clinically when treated only with vancomycin. She remained septic with a blood pressure of 80/40 mm Hg; streptomycin was added to her regimen. We were concerned that streptomycin concentrations obtained following intramuscular administration would not be adequate because of possible hypoperfusion. Based on limited published literature, streptomycin was administered intravenously via a central intravenous catheter. DISCUSSION: A review of high-level aminoglycoside-resistant S. faecalis and treatment with intravenous streptomycin therapy are discussed. The availability and monitoring of streptomycin therapy are also described. CONCLUSIONS: Streptomycin is an antimicrobial agent that must be used with vancomycin in serious infections to eradicate high-level, gentamicin-resistant S. faecalis. Its unique administration and monitoring concerns require individual patient assessment.