Impacts of Culture-Independent Diagnostic Practices on Public Health Surveillance for Bacterial Enteric Pathogens

Abstract

For decades, culture has been the mainstay of diagnostic testing for bacterial enteric pathogens. This paradigm is changing as clinical laboratories adopt culture-independent methods, such as antigen-based tests and nucleic acid-based assays. Public health surveillance for enteric infections addresses 4 interrelated but distinct objectives: case investigation for localized disease control; assessment of disease burden and trends to prioritize and assess impact of population-based control measures; outbreak detection; and microbiologic characterization to improve understanding of pathogens, their virulence mechanisms, and epidemiology. We summarize the challenges and opportunities that culture-independent tests present and suggest strategies, such as validation studies and development of culture-independent tests compatible with subtyping, that could be adopted to ensure that surveillance remains robust. Many of these approaches will require time and resources to implement, but they will be necessary to maintain a strong surveillance system. Public health practitioners must clearly explain the value of surveillance, especially how outbreak detection benefits the public, and collaborate with all stakeholders to develop solutions.

Multicenter Evaluation of Clinical Diagnostic Methods for Detection and Isolation of Campylobacter spp. from Stool

“…The use of culture-independent diagnostic tests (CIDTs) for Campylobacter testing on stool samples is increasing, which may have important implications for both patient management and public health surveillance efforts (5). Stool antigen tests to directly detect Campylobacter in fecal samples are fast and generate sameday results, but concerns regarding specificity and positive predictive value (PPV) have been raised (6,7).…”

Public health impacts of culture independent diagnostic testing in Australia

“…Many pathology laboratories have embraced PCR due to the low ongoing cost, speed, and ease of use 1,[4][5][6] . PCR requires less training and expertise, and is less subjective than culture, for which experience is required to identify appropriate colonies to select for further characterisation 1,6 .…”

“…PCR requires less training and expertise, and is less subjective than culture, for which experience is required to identify appropriate colonies to select for further characterisation 1,6 . PCR is generally more sensitive than culture, and can detect pathogens that do not grow easily in culture, have been treated with antibiotics or are in low numbers in the specimen 5,6 . PCR is more likely to detect a pathogen in specimens with decreased viability due to a delay before testing 7 .…”

“…One of the most important uses of surveillance data is for the detection of an increase in disease through comparison with historical data 5,6 . Therefore, any change in testing method will need to be reviewed in the context of previous results, to enable valid comparison of data from before and after the change in method.…”

“…Without information on the specific genotype of the pathogen, it is difficult to prove the linkage of cases to pathogen isolates obtained after traceback to the potential food source. This can affect the success of interventions or litigation 1,6 .…”