Pneumococcal colonization in nasopharynx, oropharynx and gingival sulcus among adults in Brazil

Abstract

Background : Streptococcus pneumoniae is a leading cause of community-acquired pneumonia. This pathogen can be found as part of the human commensal microbiota of the upper respiratory tract. Pneumococcal colonization is mostly asymptomatic, but is the first step to develop pneumococcal diseases. Anaerobes and oral bacteria are more frequently detected in patients with community-acquired pneumonia and it is possible that these bacteria may play more important roles in the development of this disease.Aim/Hypothesis : This study aimed to evaluate the prevalence of Streptococcus pneumoniae colonization in three different sites of healthy adults-nasopharynx, oropharynx and gingival sulcus. Material and Methods: Two-hundred sixty-five adults, aged 20-60 years, who attended dental clinics in one public university ( n = 106) and one military institution ( n = 159) were enrolled in this study. Pneumococcal detection was performed by direct culture (DC) and PCR for lytA gene after a broth enrichment step. Capsular types were determined by sequential multiplex PCR.Results : We identified 18 (6.8%) pneumococcal carriers among 265 adults by PCR, but only one (0.4%) pneumococcal strain was isolated by the DC method. Oropharynx (17, 6.4%) was the main source of S. pneumoniae. Colonization of gingival sulcus and nasopharynx was found in 4 (1.5%) and 2 (0.8%) adults, respectively. Nine distinct capsular types were detected from seven adults and co-colonization with two serotypes was confirmed in four (1.5%) subjects. Factors associated with carriage were being females, having low level of schooling, being non-military and using regular medication. We observed a low (6.8%) pneumococcal carriage prevalence, but oropharyngeal samples yielded more sensitive results, especially by the PCR-based detection methodology.Conclusions and Clinical Implications : Gingival sulcus was found to be a possible reservoir for S. pneumoniae. As dental plaque may act as a repository of S. pneumoniae this new data will clarify the knowledge of the risk factors for bacterial pneumonia which is critical to the development of strategies for the prevention and treatment of these infections. Future investigations need to consider the potential role of gingival sulcus as a reservoir of S. pneumoniae in order to establish the capacity of the oral condition to start or maintain systemic diseases.