laboratorytesting-406 The next generation of rapid lab tests is helping doctors diagnose and treat foodborne illnesses faster than ever, but health officials are concerned increasing use of the tests is decreasing their ability to detect and investigate outbreaks. Known as CIDTs, the “culture-independent diagnostic tests” provide big picture results in hours, indicating whether a person’s illness was caused by Listeria or E. coli, for example. “But without a bacterial culture, public health officials cannot get the detailed information about the bacteria needed to help find outbreaks, check for antibiotic resistance, and track foodborne disease trends,” according to the Centers for Disease Control and Prevention. In 2015, the percentage of foodborne infections diagnosed only by CIDT was about double compared with the percentage in 2012-2014. “We are working with partners to make sure we still get important information about harmful bacteria despite the increasing use of diagnostic tests that don’t require a culture,” said Robert Tauxe, director of CDC’s Division of Foodborne, Waterborne and Environmental Diseases. Growing bacterial cultures typically takes days compared to the CIDTs, which provide results in hours. The extra time required for cultures yields the extra information epidemiologists and outbreak investigators need. Cultures show if multiple patients are infected with the same isolate, or strain, of pathogens such as Salmonella, E. coli, Listeria, Cryptosporidium or Campylobacter. Determining the specific strain of a pathogen also allows investigators to rule out suspect foods as an outbreak source. For the short term, the CDC is asking for cooperation from clinical laboratories. “Clinical laboratories should work with their public health laboratories to make sure a culture is done whenever a CIDT indicates that someone with diarrheal illness has a bacterial infection,” according to CDC’s Morbidity and Mortality Weekly Report (MMWR). Limited progress in reducing foodborne illness rates The MMWR also included the most recent data from CDC’s Foodborne Diseases Active Surveillance Network, known as FoodNet. A summary of preliminary data from 2015 on nine foodborne pathogens showed the most frequent causes of infection were Salmonella and Campylobacter, as in previous years. CDC-2015-CIDTs-tests Another key finding from the FoodNet report showed the incidence of Salmonella Typhimurium infection, often linked to poultry and beef, decreased 15 percent in 2015 from 2012-2014 levels. The decline may be due in part to tighter regulatory standards and vaccination of chicken flocks against Salmonella, researchers said in the report. The 2015 data also shows an increase in some infections. Cryptosporidium infections increased 57 percent compared to 2012-2014, likely due to increased testing for this pathogen, according to the report. Reported non-O157 Shiga toxin-producing E. coli (STEC) infections increased 40 percent compared with 2012-2014. Officials theorized quicker and easier testing likely accounted for some or all of the increase. (To sign up for a free subscription to Food Safety News, click here.)