HIV Patients Receiving HAART Therapy Can Still Transmit the Virus

(36th Annual Meeting of the Infectious Diseases Society of America) Research indicates that men who are positive for human immunodeficiency virus (HIV) infection and who are undergoing treatment with highly active antiretroviral chemotherapy (HAART) may still be able to transmit the virus, even if no free HIV can be detected in their blood or seminal fluid. The study included seven patients receiving HAART therapy who had no detectable free HIV in their blood or seminal fluid. HIV provirus, a precursor of the free virus, was detected in the seminal cells of four of the seven patients. In two of the four cases, the virus was grown in vitro by cultivating provirus-containing cells with blood cells from individuals who were not infected with HIV. Genetic testing of the HIV viruses that were grown in vitro showed them to be macrophage-tropic—that is, they grow in blood cells that are most infected by a first-time HIV infection. The investigators believe this finding suggests that provirus cells may be capable of developing into infectious HIV when transmitted to the body of a noninfected individual and that patients receiving HAART should continue to practice safe sex and other behaviors that protect against the transmission of HIV.—roger j. pomerantz, m.d., et al., Thomas Jefferson University, Philadelphia.

Investigative Inhaled Influenza Agent Shortens Duration of Symptoms

(Infectious Diseases Society of America) Results of a study on the investigational drug zanamivir (Relenza) demonstrate the effectiveness of this inhalational agent in alleviating the symptoms of influenza type A and type B. The randomized, placebo controlled study included 356 patients who were 12 years or older with confirmed influenza type A or type B, including patients at high risk for complications. Within 48 hours of symptom onset, the patients received either 10 mg of zanamivir for inhalation twice daily for five days, or placebo. The patients who received zanamivir had less severe symptoms including headache, sore throat, fever, myalgia, cough, weakness and loss of appetite, compared with patients who received placebo. The patients who received zanamivir reported feeling better sooner than those who received placebo (in five days versus 7.5 days). The 32 high-risk patients who received zanamivir reported an improvement in symptoms more than two days sooner than those who received placebo (nine days versus 11.5 days), although this difference was not statistically significant. The investigators believe that because influenza can be such a debilitating disease, feeling better two days sooner can be very important to patients.—d.m. gleming, m.d., et al., Birmingham Research Unit, Royal College of General Practitioners, United Kingdom.

New Antibiotic Shows Activity Against Broad Spectrum of Pathogens

(Infectious Diseases Society of America) Results of a study of pexiganan acetate, an investigational topical antibiotic, have shown that this agent is effective against more than 3,000 clinical isolates, including gram-positive, gram-negative and anaerobic pathogens. Pexiganan is a member of a new class of peptide antibiotics called magainins. In the study, pexiganan was active in vitro against almost all species of the gram-positive microbes (16 μg per mL or less), and active against Streptococcus sanguis (64 μg per mL or less) and Enterococcus faecalis (128 μg per mL or less). It was also active against the majority of gram-negative bacteria tested, and 90 percent of these isolates were inhibited with 32 μg per mL or less of pexiganan. Pexiganan was similarly active against 417 anaerobic isolates. The investigators note that the mechanisms of action of pexiganan may explain the low incidence of bacterial resistance and the inability of researchers to induce resistance among bacteria in vitro. The antibiotic is currently being reviewed by the U.S. Food and Drug Administration for the topical treatment of infected diabetic foot ulcers.—benjamin lipsky, m.d., et al., University of Washington School of Medicine, Seattle, Washington.

Data Show Effectiveness of Intranasal Influenza Vaccine in Children

(38th Interscience Conference on Antimicrobial Agents and Chemotherapy) Data from the second year of a double-blind placebo-controlled, phase III efficacy trial in children show that an investigational intranasal influenza virus vaccine (FluMist) provided 100 percent protection against culture-confirmed strains included in the 1996-1997 influenza vaccine, and conferred 86 percent protection against A/Sydney, the predominant strain of influenza that unexpectedly circulated during the 1996-1997 influenza season. Of the 1,358 participants in the trial, five cases of influenza caused by influenza strains included in the vaccine were reported, and 66 cases caused by the A/Sydney strain occurred. Two percent (15 of 917) of the children who received the intranasal vaccine had culture-confirmed influenza, all of which was attributable to the A/Sydney strain, while 13 percent (56 of 441) of the children who received placebo contracted culture-confirmed influenza. The overall protection rate was 87 percent. None of the children who received the vaccine had lower respiratory complications.—robert belshe, m.d., et al., St. Louis University, St. Louis, Missouri.

Patients at Risk of Lung Cancer May Benefit from CT Screening

(84th Scientific Assembly and Annual Meeting of the Radiological Society of North America) Persons who smoke and those who are former smokers age 60 and older may benefit from computed tomography (CT) screening for lung cancer, according to preliminary results of a study at New York Hospital/Cornell Medical Center and New York University Medical Center funded by the National Institutes of Health. One thousand smokers and former smokers were screened in the Early Lung Cancer Action Program. Twenty-two cancers were detected by CT scanning. Of those cancers, 17 (77 percent) were in the early stage and not visible on chest radiographs. The investigators believe that CT screening of persons at risk for lung cancer could save lives, but long-term follow-up assessing cure rate and cost is necessary before a national screening program can be recommended.—claudia i. henschke, m.d., ph.d., et al., New York Hospital/Cornell Medical Center, New York City.