Clinical infections in the noninstitutionalized geriatric age group: methods utilized and incidence of infections. The Pittsburgh Good Health Study.

Because noninstitutionalized senior citizens comprise over 95% of the population 65 years of age and older, their health needs are a major concern. Data regarding infections in this population including the epidemiology, morbidity, and mortality are lacking. The authors recruited a study population of 417 free-living persons, all 65 years of age or older, from two neighborhoods in Pittsburgh, Pennsylvania. After the collection of self-reported baseline information from these persons, they were monitored for all clinical infections for 2 years, beginning July 1986 and through June 1988, using clinic visits, hospitalizations, or phone calls when needed. The baseline information showed the study population of 417 persons to be comparable with a neighborhood comparison group and with established populations for epidemiologic studies of the elderly in three other states. The 24 months of infection surveillance yielded 494 diagnosed infections in 224 or 54% of the subjects. Respiratory infections were most frequent with 259 or 52% of the total, followed by genitourinary infections with 24%, skin infections with 18%, gastrointestinal infections with 4%, and other types of infection with 2%. By comparing 22 self-reported baseline conditions with the occurrence of infection, 10 historic factors were univariately significant for infection. Of these 10 factors, only history of a lung problem (relative risk = 1.7, 95% confidence interval (CI) 1.1-2.9) and history of difficulty controlling urination (relative risk = 2.7, 95% CI 1.3-4.9) were statistically significant in multivariate analysis. To our knowledge, this study represents the first prospective data on infections in the noninstitutionalized elderly. The data demonstrate the wide variety of infections that occurred in this population and suggest that persons with a history of any one of several medical problems were possibly at greater risk for infection.

Pharmacokinetics of cephradine administered intravenously and orally to young and elderly subjects.

The pharmacokinetics of IV and oral cephradine in healthy young male and female volunteers (ages 19 to 25, n = 10) were compared to those of older individuals (ages 65 to 81, n = 9). Subjects received 1 gram of cephradine by a 5-minute intravenous (IV) infusion followed the next day by a 1-gram oral dose. Serial serum and urine samples collected over a period of 12 hours after the dose were analyzed for cephradine concentration by a microbiologic assay. After IV administration, mean serum cephradine concentrations in the elderly group were significantly higher at both 6 hours (1.52 +/- 0.41 mcg/mL) and 8 hours (0.73 +/- 0.22 mcg/mL) than in the young group at 6 hours (0.43 +/- 0.11 mcg/mL). Total systemic clearance was significantly lower (2.64 +/- 0.34 vs. 4.81 +/- 0.59 ml/min/kg) and the elimination half-life was significantly longer (1.71 +/- 0.20 vs 1.12 +/- 0.13 hours) in the elderly group (P = .0001). Systemic cephradine clearance correlated positively with creatinine clearance (r2 = 0.34, P = .0110) and negatively with age (r2 = 0.79, P = .0052). The mean volume of distribution was not significantly different between the two groups. Mean renal clearance was significantly lower in the elderly group (P = .0001), but more than 80% of the dose was excreted in the urine within 6 hours in both groups. After oral administration, the mean peak concentration and time to peak concentration did not differ between groups. The relative oral bioavailability was approximately 94% in both groups. The mean serum concentrations in the elderly were higher at both 6 and 8 hours than in the young group at 6 hours. There were no differences in pharmacokinetic parameters between male and female subjects. Because of reduced cephradine clearance secondary to an age-related decline in renal function, administration of cephradine every 8 hours, rather than every 6 hours, may be sufficient in elderly patients.

In vitro activity of BMY-28100, a new oral cephalosporin.

BMY-28100 is a new orally absorbed cephalosporin whose in vitro activity was compared with that of cefaclor. BMY-28100 was more active against Staphylococcus aureus and Haemophilus influenzae than was cefaclor. In addition, there was only a small rise in MIC50 and MIC90 values for BMY-28100 when the inoculum size was increased 100- or 10,000-fold. In contrast, MIC50 and MIC90 values increased significantly for cefaclor with similar increases in inoculum size. These data suggest that BMY-28100 may be a promising agent to test for oral administration in infections caused by S. aureus and H. influenzae.