A randomized, placebo-controlled study of oral cimetidine as an immunopotentiator of parenteral immunization with a group B meningococcal vaccine.

Cimetidine (CIM) is an H2-receptor antagonist with a long history of clinical use in peptic ulcer disease. In addition to its inhibitory effect upon gastric acid secretion, CIM can also block histamine-mediated immunosuppression by inhibiting H2 receptors on suppressor T cells. CIM results in immunoaugmentation of both cellular and humoral immunity by this mechanism and has been used clinically in the treatment of chronic infectious and neoplastic diseases. We postulated that orally administered CIM, like an adjuvant, could augment the immunologic response to a parenteral vaccine. To test this hypothesis, a randomized placebo (PLB)-controlled, double-blinded study in 14 healthy volunteers was performed using a Group B meningococcal outer membrane protein (OMP) vaccine administered twice, 6 weeks apart. Volunteers were randomized within pairs defined by their screening OMP antibody titers to receive either CIM or PLB which was administered for 5 days, beginning 2 days before each of the two immunizations. All 14 volunteers completed the study with excellent compliance. Sera were tested for anti-OMP and bactericidal antibodies. The groups were comparable in terms of gender distribution, age and baseline anti-OMP titers. Reactogenicity to the vaccine was mild and comparable between groups. There was little effect of CIM (over PLB) on anti-OMP or functional bactericidal antibody levels over time. Geometric means of maximum OMP antibody increase over baseline was 3.3-fold (95% CI: 1.8-6.3) for CIM and 2.4 for PLB (CI: 1.6-3.7). CIM had a corresponding 3.9-fold increase (CI: 1.9-8.3) in bactericidal antibody level compared to 2.2 for PLB (CI: 1.4-3.4). We conclude that oral CIM was not effective as an immunopotentiator of immunization with this group B meningococcal vaccine.

Use of azithromycin for the treatment of Campylobacter enteritis in travelers to Thailand, an area where ciprofloxacin resistance is prevalent.

We evaluated the use of azithromycin (500 mg) or ciprofloxacin (500 mg) daily for 3 days for the treatment of acute diarrhea among United States military personnel in Thailand. Stool cultures were obtained and symptoms were recorded on study days 0, 1, 2, 3, and 10. Campylobacter species were the most common pathogen isolated (44 isolates from 42 patients). All Campylobacter isolates were susceptible to azithromycin; 22 were resistant to ciprofloxacin. Among the 42 patients with campylobacter infection, there were 2 clinical and 6 bacteriologic treatment failures in the ciprofloxacin group and no treatment failures in the azithromycin group (P = .021 for bacteriologic failures). Overall, azithromycin was as effective as ciprofloxacin in decreasing the duration of illness (36.9 hours vs. 38.2 hours, respectively) and the number of stools (6.4 vs. 7.8, respectively). Among those not infected with Campylobacter species (n = 30), the duration of illness was 32.9 hours vs. 20.7 hours (P = .03) for the azithromycin and ciprofloxacin groups, respectively. Azithromycin is superior to ciprofloxacin in decreasing the excretion of Campylobacter species and as effective as ciprofloxacin in shortening the duration of illness. Azithromycin therapy may be an effective alternative to ciprofloxacin therapy in areas where ciprofloxacin-resistant Campylobacter species are prevalent.