Detection of pneumococcal carriage in asymptomatic healthcare workers

Abstract

BackgroundHealthcare workers are at increased risk of exposure to respiratory pathogens includingStreptococcus pneumoniae(pneumococcus). While little asymptomatic carriage has been reported in young-to-middle-aged adults, this may be due to non-sensitive diagnostic methods. The aim of the study was to investigate the rates of pneumococcal carriage in a large cohort of healthcare workers using saliva as a respiratory specimen.MethodsWe evaluated the prevalence of pneumococcal carriage in a convenience sample of saliva, self-collected from asymptomatic healthcare workers at Yale New Haven Hospital (CT, USA) who were testing for SARS-CoV-2 from March 30 to June 11, 2020. Samples were transported at ambient temperature and stored at −80°C within 12 hours. DNA extracted from the culture-enriched saliva was later tested using qPCR forpiaB, lytA, and serotype. Saliva samples were considered positive for pneumococcus when thepiaBCt value was <40.ResultsStudy participants were 22-74 years old (mean=38.5), 75% female, 75% white, with occupations including registered nurses (48%), medical doctors (23%), and patient care assistants (5%). Overall, 138/1241 (11%) samples from 86/392 (21%) individuals testedpiaB-positive for pneumococcus at some point during the 4-month study period, with 28 (33%) colonized individuals positive at multiple time points. Carriers reflected the overall study population. No significant demographic characteristics were associated with detection of pneumococcus. Colonized individuals primarily carried serotypes 19F (25%) and 3 (12%), however, we were unable to resolve a primary serotype for 31% of all pneumococcus-positive samples identified.ConclusionsDuring a period of mandatory masking, we identified a cumulative pneumococcal carriage prevalence of 21% among healthcare workers. This study highlights that healthcare workers may act as unrecognized reservoirs of pneumococcus in the population. Despite long-standing PCV7 and PCV13 pediatric immunization programs, vaccine serotypes continue to be prevalent among the adult population.