Study Shows New Bacterial Testing Technology May Be Step in the Wrong Direction for Food Safety

The US Center for Disease Control and Prevention has released its preliminary report on pathogens transmitted by food for the year 2015. According to the report, new and changing tests that aid epidemiologists in identifying foodborne infections may soon become part of the problem. As the medical community begins to turn from the traditional culture methods towards new, more rapid testing technology, he agency says that the new tests may begin to “pose challenges to finding outbreaks,” slowing progress toward preventing foodborne disease through monitoring and reporting illnesses and outbreaks.

Relatively new, culture-independent diagnostic tests have somewhat revolutionized the way that medical professionals and diagnose and treat foodborne disease. The tests, also known as CIDTs, allow doctors to diagnose foodborne illnesses and infections much more rapidly than the previous diagnostic method.

Traditional Stool Culture Methods – Does Slow but Steady Win the Race?

Historically, doctors have had to utilize traditional culture methods.  A fecal culture – also referred to as a stool culture or enteric pathogens culture – are laboratory tests that require collecting a sample of a patient’s feces for testing. These culture methods require growing bacteria to determine what is causing illness, which takes time – much more time than many other laboratory tests.

The procedure yields a sample that ultimately assists medical professionals in learning about the bacteria that currently exists in a patient’s digestive tract, which helps doctors diagnose bacterial infections.

In the context of foodborne illness, one of the issues with fecal cultures has been the hesitancy of medical professionals to actually order the test. The results longer to come back than many other tests. Further, many cases of foodborne illness are not severe enough to warrant ordering such a test, and will resolve with no additional treatment in a number of days.

Many people with food poisoning self-treat and never seek help from a doctor or registered nurse for their illness. In those cases, there is no chance to order the test in the first place.

If the illness is severe enough, the results of a fecal culture can help determine the appropriate antibiotic or other treatment plan. Alternatively, results may indicate that no further additional professional or pharmacological treatment is necessary.

Many types of bacteria cause food poisoning – Shigella, Salmonella, E. coli and Listeria to name a few – but what many people don’t know is that there are many different strains of each type of bacteria. Not only are the bacteria divided into serotypes, which is what people generally refer to as a “strain” of the bacteria as, they are further divided into very specific groups that are genetically related.

It comes as a surprise to many to find out that bacteria have genes and DNA just like people do. Though the organisms have fewer genes than humans, there are still more than enough to identify groups of bacteria that are genetically very similar or identical. Clusters of cases – which are often precursors to or parts of outbreaks – are identified when epidemiologists isolate a group of people with food poisoning caused by bacteria that is genetically very closely related.

Faster Test Results: Worth Losing Out on Long-Term Progress Towards Safer Food

CIDTs allow public health officials to diagnose a patient’s sickness much faster, and even identifies the bacteria responsible for the illness. However, the absence of a bacterial culture also means that officials are unable to get more detailed information about the specific bacteria that is making the person sick.

Without a stool culture, however, laboratory technicians, epidemiologists and other public health officials and medical experts are unable to get detailed genetic information about the bacteria sampled. This means that they are also unable to test whether or not the bacteria is resistant to antibiotics, a dangerous phenomenon that is growing quickly in the US and worldwide. With the increase of CIDT tests and corresponding decrease in fecal testing, that trend may well continue.

According to the CDC, “in 2015, the percentage of foodborne infections diagnosed only by CIDT was about double compared with the percentage in 2012-2014.” The preliminary report concludes that since “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,” our new more sophisticated tests may actually prove to be a step backwards in our efforts to increase food safety.