Bacteremic Streptococcus pneumoniae in Community-Acquired Pneumonia: An Update

Invasive pneumococcal disease is a major cause of morbimortality worldwide. The presence of bacteremia in pneumococcal pneumonia constitutes an additional factor of worse prognosis, although the highest virulence of invasive pneumococcal infection is clustered in certain serotypes. Antibiotic resistances are a challenge for the clinician when choosing the most appropriate antibiotic treatment. However, the influence of these in the evolution of the disease is a controversial issue, and it is clinically irrelevant if the MIC is lower than 4 μg/ml. The control of antibiotic pressure on Streptococcus pneumoniae has proved the most effective tool for monitoring resistances. Prevention strategies through pneumococcal vaccination have been shown to reduce the incidence of invasive pneumococcal disease in vaccinated children and the unvaccinated adult population. However, a phenomenon of increased infections by serotypes not included in the vaccine has been described. The development of antibiotics and vaccination have achieved great progress in the control of this disease, although Streptococcus pneumoniae continues to develop mechanisms of survival and adaptation.