Population-based incidence of infection with selected bacterial enteric pathogens in children younger than five years of age, 1996-1998.

BACKGROUND: Previous studies of bacterial enteric infections have suggested a disproportionate disease burden for children younger than 5 years of age. OBJECTIVES: This study describes population-based incidence of culture-confirmed infections with 6 bacterial enteric pathogens in children younger than 5 years of age in the Foodborne Diseases Active Surveillance Network (FoodNet), 1996-1998. METHODS: Cases were ascertained through active laboratory-based surveillance in Minnesota, Oregon and selected counties in California, Connecticut, Georgia, Maryland and New York. RESULTS: Twenty-one percent (5218 of 24,358) of infections were in children younger than 5 years of age, but this age group made up only 7% of the total person-years of observation. Among those younger than 5 years of age, the incidence (cases per 100,000 person-years) for each pathogen was: Salmonella, 55.3; Campylobacter, 43.4; Shigella, 32.7; E. coli O157, 10.3; Yersinia enterocolitica, 7.1; Listeria monocytogenes, 0.7. Incidence varied widely among the 7 FoodNet sites. CONCLUSIONS: This study confirmed a disproportionate disease burden in young children. Investigation of risk factors specific to this age group and review and enhancement of current prevention and control strategies for children younger than 5 years of age may reduce illness.

Factors affecting surveillance data on Escherichia coli O157 infections collected from FoodNet sites, 1996-1999.

To determine the burden of illness caused by Escherichia coli O157 infections in populations in Foodborne Diseases Active Surveillance Network (FoodNet) surveillance areas, we initiated active, laboratory-based surveillance and surveyed laboratories, physicians, and the general public regarding the factors associated with the diagnosis and surveillance of infection with E. coli O157. We evaluated survey responses and site-specific incidence, outbreak, and demographic data during 1996-1999. A total of 1425 laboratory-confirmed cases of E. coli O157 infection and 32 outbreaks were reported from the 5 original FoodNet sites. The average annual incidence ranged from 0.5 cases/100,000 population in Georgia to 4.4 cases/100,000 population in Minnesota. After excluding outbreak-associated cases, the annual incidence of sporadic, laboratory-confirmed E. coli O157 infections remained relatively stable during 1996-1999, with a range of 1.9-2.3 cases/100,000 population. Regional differences in incidence partly resulted from differing physician and laboratory practices and from site-specific exposure factors (e.g., living on or visiting farms).

Laboratory practices for stool-specimen culture for bacterial pathogens, including Escherichia coli O157:H7, in the FoodNet sites, 1995-2000.

In 2000, we surveyed microbiologists in 388 clinical laboratories, which tested an estimated 339,000 stool specimens in 1999, about laboratory methods and policies for the routine testing of stool specimens for Salmonella, Shigella, Campylobacter, and Vibrio species, Yersinia entercolitica, and Escherichia coli O157:H7. The results were compared with those of similar surveys conducted in 1995 and 1997. Although these laboratories reported routinely testing for Salmonella, Shigella, and Campylobacter species, only 57% routinely tested for E. coli O157:H7, 50% for Y. entercolitica, and 50% for Vibrio species. The mean proportions of stool specimens that yielded these pathogens were as follows: Campylobacter, 1.3% of specimens; Salmonella, 0.9%; Shigella, 0.4%; and E. coli O157:H7, 0.3%. The proportion of laboratories that routinely tested for E. coli O157:H7 increased from 59% in 1995 to 68% in 2000; however, the proportion of stool specimens tested decreased from 53% to 46%. E. coli O157:H7 should be routinely sought in stool specimens submitted for microbiologic culture.

Consumer attitudes and use of antibiotics.

Recent antibiotic use is a risk factor for infection or colonization with resistant bacterial pathogens. Demand for antibiotics can be affected by consumers' knowledge, attitudes, and practices. In 1998-1999, the Foodborne Diseases Active Surveillance Network (FoodNet( conducted a population-based, random-digit dialing telephone survey, including questions regarding respondents' knowledge, attitudes, and practices of antibiotic use. Twelve percent had recently taken antibiotics; 27% believed that taking antibiotics when they had a cold made them better more quickly, 32% believed that taking antibiotics when they had a cold prevented more serious illness, and 48% expected a prescription for antibiotics when they were ill enough from a cold to seek medical attention. These misguided beliefs and expectations were associated with a lack of awareness of the dangers of antibiotic use; 58% of patients were not aware of the possible health dangers. National educational efforts are needed to address these issues if patient demand for antibiotics is to be reduced.

Antimicrobial resistance among Campylobacter strains, United States, 1997-2001.

We summarize antimicrobial resistance surveillance data in human and chicken isolates of Campylobacter. Isolates were from a sentinel county study from 1989 through 1990 and from nine state health departments participating in National Antimicrobial Resistance Monitoring System for enteric bacteria (NARMS) from 1997 through 2001. None of the 297 C. jejuni or C. coli isolates tested from 1989 through 1990 was ciprofloxacin-resistant. From 1997 through 2001, a total of 1,553 human Campylobacter isolates were characterized: 1,471 (95%) were C. jejuni, 63 (4%) were C. coli, and 19 (1%) were other Campylobacter species. The prevalence of ciprofloxacin-resistant Campylobacter was 13% (28 of 217) in 1997 and 19% (75 of 384) in 2001; erythromycin resistance was 2% (4 of 217) in 1997 and 2% (8 of 384) in 2001. Ciprofloxacin-resistant Campylobacter was isolated from 10% of 180 chicken products purchased from grocery stores in three states in 1999. Ciprofloxacin resistance has emerged among Campylobacter since 1990 and has increased in prevalence since 1997.