Identifying a Level of Neutralizing Antibody That Correlates With Protection From Clinical Mumps Disease During a 2017 Mumps Outbreak Among Military Service Members.

Background: In 2017, a mumps outbreak occurred in a US military barracks. Serum collected at service entry was used to compare pre-exposure with presumptive vaccine-induced antibody levels from persons who developed mumps (cases) and potentially exposed persons who did not develop mumps (non-cases). Sufficient information to determine levels of exposure during the outbreak was not available. Methods: Pre-outbreak serum samples from the Department of Defense Serum Repository were available from 254 potentially exposed service members. Twelve developed clinical symptoms and had post-outbreak serum collected. All sera were tested with a mumps-specific enzyme immunoassay for immunoglobulin M, immunoglobulin G (IgG), and IgG avidity. The neutralizing antibodies to vaccine strain (Jeryl Lynn [JL], genotype A) and wildtype virus (genotype G) was assessed by a plaque reduction neutralization test. A Fisher exact test and receiver operator characteristic curve were used to analyze the antibody response for non-cases and mumps cases. Results: Eight mumps cases were laboratory confirmed. Pre-outbreak neutralizing antibody titers to JL and genotype G mumps virus and pre-outbreak IgG index values were proportionately lower for most cases as compared with exposed non-cases. When compared with potentially exposed non-cases, cases with clinical symptoms had greater odds of having a pre-outbreak JL titer <41 and a genotype G titer <16. Conclusions: We identified potential correlates of protection for mumps neutralizing antibody titers against JL and genotype G mumps viruses.

Evaluation of a two step testing algorithm to improve diagnostic accuracy and stewardship of Clostridioides difficile infections.

In response to national guidelines, we implemented a two-step testing algorithm for Clostridioides difficile in an effort to improve diagnostic accuracy. Following implementation, we analyzed treatment frequency between discordant and concordant patients. We found that the majority of discordant cases were treated with no significant differences in patient characteristics or outcomes between the concordant and discordant groups. Additionally, there were no differences in outcomes when discordant patients were further stratified by treatment status. Given little added diagnostic accuracy with the addition of EIA toxin testing, our facility resumed diagnosis by PCR testing alone. Further studies are needed to investigate alternative processes for improvement in diagnostic accuracy aside from toxin EIA testing including stool submission criteria and educational programs.