Detection of pneumococcal carriage in asymptomatic healthcare workers
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Background
Healthcare workers are at increased risk of exposure to respiratory pathogens including Streptococcus 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.
Methods
We 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 for piaB, lytA , and serotype. Saliva samples were considered positive for pneumococcus when the piaB Ct value was <40.
Results
Study 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 tested piaB -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.
Conclusions
During 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.
