Echinostoma friedi: the effect of age of adult worms on the infectivity of miracidia.

The effect of ageing of adults of Echinostoma friedi (Trematoda: Echinostomatidae) on the infectivity of miracidia yielded was analysed. Miracidia were obtained after hatching of eggs obtained from adult worms of E. friedi collected weekly during the course of experimental infections in golden hamsters. Miracidial infectivity, measured in terms of percentage of infection in Lymnaea peregra, was significantly influenced by the age of the adult worms from which the miracidia were derived. Infective miracidia only were obtained from adult worms in the age range from 4 to 9 weeks post-infection. Infectivity was maximal in those miracidia derived from adults collected 8 and 9 weeks post-infection. The results suggest that adult worms producing viable eggs require additional maturation to be able to yield eggs containing infective miracidia.

An experimental study of the reproductive success of Echinostoma friedi (Trematoda : Echinostomatidae) in the golden hamster.

Viable eggs produced weekly per infective stage was used as a measure of the reproductive success of Echinostoma friedi during the first 12 weeks of infection in hamsters. The weekly reproductive success was not constant during the experiment in relation to the egg output and the proportion of viable eggs produced. The egg release started during week 2 post-inoculation, attaining a maximum during week 3. A decline in egg output was observed from week 9. Viable eggs were only produced from week 3 post-inoculation and a maximum was attained at week 4 of the experiment. A decline in egg viability was observed from week 9. Considering together the egg output and the egg viability, the maximum weekly reproductive success was obtained during week 4 post-inoculation. The changes in the weekly reproductive success were not reflected in variations in worm numbers and body sizes during the course of the infection. The humoral immune response of golden hamsters during the infection with E. friedi was determined. Increases of IgG levels against somatic and excretory/secretory products of E. friedi were detected coinciding with the reduction in the reproductive success.

The effect of BCG vaccination on tuberculin reactivity and the booster effect among hospital employees.

BACKGROUND: We estimated the effect of remote BCG vaccination on tuberculin reactivity and the booster effect among hospital employees. METHODS: Cross-sectional survey at a university hospital. All personnel employed during a 24-month period were included in the study. Employees were administered 2-step tuberculin testing, and BCG vaccination scars were verified. RESULTS: Of 665 hospital employees studied, 239 (36%) had been vaccinated with BCG in childhood. Significant tuberculin reactions (> or =5 mm) were more frequent among BCG-vaccinated (60%) than among nonvaccinated (29%) employees (odds ratio [OR], 3.6; 95% confidence interval [CI], 2.6-5.2). The predictive value of tuberculosis infection increased with increasing reaction size and greater age (from 37% in subjects 30 years or younger with indurations > or =5 mm to 100% in subjects 50 years or older with indurations > or =15 mm). Among 374 employees with a negative tuberculin test reaction who underwent a second test, 39 (43%) of 91 vaccinated subjects had a positive booster reaction in contrast to 51 (22%) of 232 nonvaccinated subjects (OR, 3.4; 95% CI, 2-5.7). Neither different size criteria nor different definitions of the booster effect had an impact on the predictive value of tuberculosis infection. CONCLUSIONS: Remote BCG vaccination largely influences the tuberculin reaction and the boosting phenomenon among hospital employees. The interpretation of the results of 2-step tuberculin testing in a BCG-vaccinated subject must take into account age, size of the reaction, and local prevalence of tuberculosis infection. No single criterion, however, can accurately separate reactions caused by true infection from those caused by BCG vaccination.

Invasive disease caused by ciprofloxacin-resistant uropathogenic Escherichia coli.

To evaluate the invasiveness of ciprofloxacin-resistant Escherichia coli isolated from the urinary tract, the susceptibility to ciprofloxacin of Escherichia coli strains from patients with invasive urinary tract infection was compared with that of isolates from patients with noninvasive disease. In a 14-month period, 2054 different isolates of Escherichia coli were analyzed, of which 554 (27%) were resistant to ciprofloxacin. One hundred twelve (5.4%) strains were isolated from patients with invasive disease. Resistance was significantly less frequent in isolates from patients with invasive disease (4.5%) than in isolates from patients with noninvasive disease (28.3%) (OR, 0.12; CI 95%, 0.05-0.29; P<0.001). Most ciprofloxacin-resistant strains associated with invasive disease were isolated from bacteremic patients who had recently undergone an invasive procedure involving the urinary tract. Invasive disease is caused more frequently by ciprofloxacin-susceptible strains of Escherichia coli, suggesting that resistance to ciprofloxacin may decrease the invasiveness of uropathogenic Escherichia coli.