Highlights of the 42nd Interscience Conference on Antimicrobial Agents and Chemotherapy

for Community-Acquired Pneumonia Speaker: John Pullman, MD, Infectious Diseases Specialist, Internal Medicine, Mercury Medical Center, Butte, Montana. Telithromycin (KetekTM, Aventis), administered once daily for five to ten days to patients with CAP, has been found to be as effective and safe as standard twice-daily, 10-day treatment with clarithromycin (Biaxin, Abbott), a commonly prescribed macrolide; this suggests that in an environment of increasing macrolide resistance, telithromycin might be an effective alternative for the treatment of patients with CAP. Data were analyzed from two phase III, multicenter, actively controlled, randomized, double-blind trials of telithromycin versus clarithromycin for the treatment of CAP in 1,023 patients, focusing on antibacterial activity against Streptococcus pneumoniae, particularly erythromycin-resistant strains. In the first study, 448 patients received either oral telithromycin 800 mg once daily or oral clarithromycin 500 mg twice daily for 10 days. In the second study, 575 patients received either telithromycin 800 mg once daily for 5 days, telithromycin 800 mg once daily for 7 days, or clarithromycin 500 mg twice daily for 10 days. In S. pneumoniae–associated (either single-pathogen or mixed-pathogen) infections, telithromycin was clinically and bacteriologically effective in 97.7% of patients; clari thromycin was effective in only 75%. In addition, telithromycin was active in 88.9% of patients with erythromycin-resistant S. pneumoniae; clarithromycin was active in only 75%. Once-Daily Antiherpetic Agent for Suppression of Genital Herpes Speaker: Lawrence Corey, MD, Professor of Medicine and Laboratory Medicine, and Head, Virology Division, University of Washington; and Head of the Program in Infectious Diseases, Fred Hutchinson Cancer Research Center, Seattle, Washington. A daily dose of valacyclovir as suppressive therapy has been shown to reduce the transmission of symptomatic genital herpes by 77% in healthy heterosexual monogamous couples. Overall, 1,484 couples were randomly assigned in a doubleblind study and were included in the intent-to-treat population. The herpes simplex virus-2 (HSV-2)–seropositive source partners with a history of fewer than 10 episodes per year were randomly assigned, in a 1:1 ratio, to receive valacyclovir 500 mg once daily or placebo for eight months. The HSV-2 seronegative-susceptible partners were monitored monthly for clinical or subclinical (serological) acquisition of genital herpes. All couples were provided with condoms and were counseled on safer sexual behavior at all study visits. The primary endpoint was the proportion of susceptible partners with a first episode of symptomatic genital herpes, confirmed by HSV-2 culture, polymerase chain reaction (PCR), or seroconversion. The secondary endpoint was the presence of genital HSV-2 in the susceptible partners. A total of 741 source partners received placebo, and 743 received valacyclovir. In total, 488 susceptible partners were women and 996 were men. The study showed that once-daily suppressive therapy with valacyclovir reduced the transmission of symptomatic genital herpes by 77% compared with placebo. Seventeen subjects (2.3%) in the placebo group and four (0.5%) in the valacyclovir group acquired symptomatic genital herpes. In addition, suppressive antiherpetic therapy decreased laboratory-confirmed genital herpes and/or seroconversion in partners who did not develop active cases of the disease by Dr. Prescott is a medical, health, and science writer based in San Diego, California, and a former medical microbiologist and clinical pathologist for the World Health Organization. Highlights of the 42nd Interscience Conference on Antimicrobial Agents and Chemotherapy