Laboratory Surveys

More than 650 clinical laboratories in the FoodNet surveillance area test specimens from ill people. These laboratories differ in their routine testing practices for foodborne pathogens and in methods they use. Such differences may contribute to variation in the incidence rate of reported infections between FoodNet sites. To understand current practices and to monitor changes in practices over time, FoodNet conducts periodic surveys of all clinical laboratories within the surveillance area.

FoodNet conducted general surveys in 1995 (during the pilot phase of FoodNet surveillance), 1997, and 2000, and pathogen-specific surveys in 2005 and 2007. A brief summary of results, links to the survey protocols, questionnaires, and a list of publications describing results are included below. In 2010, FoodNet began to routinely survey clinical laboratories serving surveillance catchment area residents on the use of new testing methods to detect enteric pathogens in stool specimens.

In 1995, 1997 and 2000, surveys were conducted to describe laboratory methods and policies for the routine testing of stool specimens for Salmonella, Shigella, Campylobacter, Vibrio, Yersinia entercolitica, and Escherichia coli O157:H7. Results showed that all or almost all laboratories routinely test for Salmonella, Shigella, and Campylobacter, but only about half routinely tested for E. coli O157:H7, Yersinia entercolitica, or Vibrio spp. In 2000, labs were also queried about testing practices for parasitic agents. Most laboratories sent specimens off site for parasitic screening and did not routinely test fecal specimens for Cryptosporidium species or Cyclospora cayetanensis unless requested by a physician.

Reference:
  • Voetsch AC, Angulo FJ, Rabatsky-Ehr TR, Shallow S, Cassidy M, Thomas SM, Swanson E, Zansky SM, Hawkins MA, Jones TF, Shillam PJ, Van Gilder TJ, Wells JG, Griffin PM. Laboratory practices for stool-specimen culture for bacterial pathogens, including Escherichia coli O157:H7, in the FoodNet sites, 1995-2000. Clin Infect Dis. 2004;38(Suppl 3):S190-197.
  • Jones JL, Lopez A, Wahlquist SP, Nadle J, Wilson M. Survey of clinical laboratory practices for parasitic diseases. Clin Infect Dis. 2004;38(Suppl 3):S198-202.

In 2005, FoodNet conducted a survey to describe laboratory characteristics, stool specimen collection methods, transport methods and times, and culture and incubation procedures used to isolate and identify Campylobacter. Results showed that adherence to existing recommendations for isolation and identification of Campylobacter varied substantially between laboratories and that many were using techniques likely to reduce their ability to isolate Campylobacter.

An electronic copy of the questionnaire and protocol is not currently available. Please contact foodnet@cdc.gov to request a copy.

References:
  • Hurd S, Demma L, Tong X, et al; EIP FoodNet Working Group. Clinical laboratory practices for the identification of Campylobacter in FoodNet Sites: Do differences explain variation in incidence rates. [Abstract]. International Conference on Emerging Infectious Diseases, Atlanta, GA, March 19-22, 2006.
  • Hurd S, Patrick M, Hatch J, Clogher P, Wymore K, Cronquist A, Segler S, Robinson T, Hanna S, Smith G, Fitzgerald C. Clinical Laboratory Practices for the Isolation and Identification of Campylobacter in Foodborne Diseases Active Surveillance Network (FoodNet) Sites: Baseline Information for Understanding Changes in Surveillance Data. Clin Infect Dis. 2012 Jun;54 Suppl 5:S440-5.

In 2007, FoodNet conducted a survey to describe culture-based and culture-independent testing practices for STEC identification. Results showed that most laboratories complied with recommendations for O157 STEC testing by culture but not with recommendations for detection of non-O157 STEC.

An electronic copy of the questionnaire and protocol is not currently available. Please contact foodnet@cdc.gov to request a copy.

Reference: