Pneumococo

Pneumococo, commonly referred to by its scientific name Streptococcus pneumoniae, is a Gram-positive, alpha-hemolytic diplococcus that colonizes the human nasopharynx. It is encapsulated, with a polysaccharide capsule that defines many serotypes.

The capsule is a major virulence factor; pneumolysin, autolysis, and the ability to form biofilms contribute to disease; although often part of the normal upper respiratory flora, pneumococcus can invade sterile sites.

Pneumococcal disease includes pneumonia, meningitis, bacteremia, otitis media, and sinusitis; less commonly it causes endocarditis or septic arthritis.

It spreads primarily by respiratory droplets and colonizes the nasopharynx; risk factors include young age, older age, asplenia, immunosuppression, smoking, and crowded living conditions.

Diagnosis relies on culture of blood or CSF in invasive disease, CSF analysis for meningitis, sputum culture, urinary antigen testing, PCR, and radiographic evidence in pneumonia.

Vaccination reduces disease burden. Pneumococcal vaccines include conjugate vaccines (PCV) and polysaccharide vaccines (PPSV23). Conjugate vaccines reduce carriage and transmission; modern programs include PCV15 and PCV20, with PPSV23 recommended for adults 65 and older and other at-risk groups.

Treatment depends on susceptibility and site of infection. For noninvasive disease, penicillin or amoxicillin is common; macrolide resistance is increasing. Alternatives include amoxicillin-clavulanate or cephalosporins; invasive disease may require vancomycin plus a third-generation cephalosporin, guided by local guidelines.

Epidemiology and public health: Streptococcus pneumoniae remains a leading cause of pneumonia and meningitis worldwide; vaccination programs have reduced incidence and mortality in many regions, and serotype distribution informs vaccine design.