Streptococcus pneumoniae biofilms and human infectious diseases: A review

Streptococcus pneumoniae (S. pneumoniae or pneumococci) is a Gram-positive bacterium and colonizes in the nasopharynx asymptotically and causes infection under immune-compressed conditions. Pneumococci colonize nasopharynx in the form of biofilms, which are adherent communities of bacteria to the biotic or abiotic surface and surrounded by extracellular polymeric (ECP) matrix. These pneumococci biofilms act as a reservoir of bacteria, and the planktonic bacteria from biofilm transit to other anatomical sterile site and cause infection. For example, if pneumococci transit from nasopharynx to the lungs, they cause pneumonia, to middle ears cause otitis media (OM), in blood cause bacteremia, in the brain cause meningitis. S. pneumoniae biofilms are resistant to antibiotics and required elevated concentration of antibiotics to eradicate biofilms, and give rise to recurrent infections and persister cells. The antibiotic resistance of pneumococci biofilm is due to biofilm matrix that embedded bacteria. With the advancement of medical science, new information about pneumococci biofilms is revealed, new strategies to combat pneumococci biofilm are proposed by various researchers. In this chapter, we provided an overview on pneumococcal biofilms and their impact on human health.