Serotypes and antibiotic susceptibility of Streptococcus pneumoniae isolated from hospitalized patients with community-acquired pneumonia in Italy

Background: Pneumonia remain an important public health problem. The primary objective was to determine the proportion of community-acquired pneumonia that is attributable to Streptococcus pneumoniae infection; secondary objectives were the description of community-acquired pneumonia attributable to Streptococcus pneumoniae according to socio-demographic and clinical variables, the clinical evolution of community-acquired pneumonia and the description of the serotype distribution of vaccine-preventable disease and antibiotic resistance rate of pneumococcal infections. Methods: An observational, prospective study was conducted on consecutive patients coming from the community, who were hospitalized with pneumonia. Data on admission, at discharge and 30 days after discharge were collected. Logistic regression models were used to evaluate the risk factors independently associated with pneumococcal pneumonia. Results: Among the 193 patients enrolled in the study, the etiology of community-acquired pneumonia was identified in 60 patients (33%) and 35 (18%) of evaluable patients had community-acquired pneumonia due to Streptococcus pneumoniae. Of all clinical characteristics, if no previous antibiotic treatment was performed, there was a 13-fold higher risk of presenting community-acquired pneumonia due to Streptococcus pneumoniae (odds ratio, 12.9; 95% confidence interval, 1.42–117.9). Moreover, the most frequent isolated serotypes were 35F, 3 and 24 (29%, 23% and 16%, respectively). Conclusion: The most frequent serotypes in pneumococcal community-acquired pneumonia are 35F, 3, 24, 6 and 7A, and thus almost 50% of Streptococcus pneumoniae strains could be covered by pneumococcal conjugate vaccine 13 in adult patients with risk factors for pneumococcal infections.