Dramatic decrease of Streptococcus pneumoniae infections in Marseille, 2003-2014.

We studied the evolution of the prevalence of pneumococcal infections in university hospitals in Marseille, France, from January 2003 to December 2014, and compared our observations and results to available international data. We collected data referring to patients hospitalised for Streptococcus pneumoniae infections in the four university hospitals of Marseille from January 2003 to December 2014. We then calculated percentages of positiveness to pneumococcal strains by dividing the annual number of patients infected by pneumococcal strains by the annual number of patients found to be infected by at least one bacterial species in the settings of interest throughout the study period. Overall, 2442 non-redundant patients were infected by S. pneumoniae strains throughout the study period. We observed that the annual percentage of patients infected by S. pneumoniae significantly decreased throughout the study period (from 1.99% in 2003 to 0.77% in 2014, p-value < 10(-4)). A significant correlation was obtained comparing the annual evolution of the percentage of patients positive to pneumococcal strains aged under 21 years to that of patients aged over 21 years (r = 0.93, p-value < 10(-5)). Our results allowed us to prove that national immunisation programmes effectively impact on the pneumococcal infection prevalence in young and elderly populations, even on the regional scale.