We will perform an initial test of viability for a new technique that promises to rapidly and accurately serotype Salmonella isolates. Over 400 deaths, 20k+ hospitalizations and 1.2M illnesses in the United States each year are caused by Salmonella according to the Centers for Disease Control and Prevention (CDC Salmonella Atlas 2013). This pathogen causes the most gastroenteritis and can cause invasive, life threatening infections. Containment of outbreaks requires additional strain characterization to the serotype level. Serotypes are established according to the Kauffman-White scheme, which enables the ability to track and identify outbreaks and a method to determine the success of control efforts. The current serotyping methods are laborious, resulting in high cost and delayed delivery of information. The cost (including capital, facilities, and training) limits its wide spread use. The burden of serotyping falls to state and local public health labs, national reference labs, and government labs. The delays occur from shipping and confirmation of species using conventional techniques and can take up to ten days to obtain results. These delays provide more time for contaminated food vectors to remain in consumer hands and create further infections. We have begun to develop a microdevice technology based on dielectrophoresis that differentiates specific pathogens based on their biophysical properties. This approach is in distinct contrast to genotyping, expression profiles, phenotyping, or metabolic tests, all of which require the laborious procedures and resources noted. Pathogenic and non-pathogenic E. coli have been differentiated using this strategy and gentamicin resistant S. epidermidis and S. aureus have been isolated from their susceptible strains. Data and theory suggests each serotype can be selectively isolated and concentrated thus providing its identity. This proposal is limited to producing a proof-of-principle data set by evaluating the CDC Salmonella validation kit to understand if this strategy is worth further pursuit. An optimized device will be developed and sample property requirements established. The proposed work will directly assess the sensitivity and specificity and provide an estimate for the speed of identification and a rough estimate of the cost. If the data suggest this is a viable strategy, future studies can include characterization of further isolates, more accurate estimates of cost, precise determination of speed, and the development of user-friendly and handheld interfaces. The upside for biophysical serotyping is excellent: results in minutes, minimal cost, wide distribution, and no cold-chain reagents.
New capabilities in biophysical separations promise the direct serotyping of Salmonella isolates. This will allow timely and inexpensive results, enabling rapid detection of outbreaks, decreasing suffering, disability and cost of care, and ultimately limiting the spread of disease.
