Streptococcus Pneumoniae

Gram + coccicomplex nutritional requirementsmany fastidiouscatalase negstrict anerobes to facultative anerobes to capnophilicdifferentiation of species is complex

Oropharynx and nasopharynx of health ind. disease results from trauma resulting in spreading of organisms colonizing the pharynxhigh infection rate in children and elderlymajor resistance problemshigh infectious dose unless pro-inflammatory signal is present - then only 10 cells needed*more about the host response to infection than specific toxins

Capsulepiliamidasepneumolysinh202 productionphosphocholineIgA protease

MOST IMPORTANT virulence determinantpolysaccharideantiphagocytic90+ serotypesproduction of antibodies to capsule is best protection against disease

Adhesionsallows for attachment to epithelial tissue

Enhances release of cell wall components (peptioglycan and teichoic acids)triggers inflammation and the alternate complement pathway

(associated mainly with pneumonia)major mediator of damage to respiratory epitheliumbinds to cholesterol - disrupts cell membranetrigger inflammation and the classic complement pathwayprevents oxidative burst

Causes damage to host tissue (usual bc usually h202 damages bacteria)no catalase to break this down

Present in bacterial cell wallbinds receptors to platelet activating factor preventing clottingfacilitates spread to blood, CSF, etc

Secretory IgA facilitates binding of bacteria to mucinnormally, secretory IgA facilitates bacterial binding to mucin the protease prevents this, allowing the organism to persist in the respiratory tract

Pneumococcal pneumoniasinusitisotitis mediapneumococcal meningitisbacteremia

Most common cause of bacterial pneumoniausually associated w/ viral respiratory disease (influenza) coupled w/ aspiration of S. pneumoniaethe viral infections impedes clearance of S. pneuomiaethe spread of S. pneumoniae results in lung inflammation usually in lower lobes

Viral infection is present 1-3 days priorat oneset of pneumonia: sustained fever (102-105) shaking, chills, chest pain, blood in sputum may have: nausea, vomiting, headache
later causes severe tissue damage

Due to invasion of organism across mucosal surface into paranasal sinusesviral infection can precede sinusitisS. pneumoniae is common cause of acute sinusitis but often not cultured

Children more susceptible (bc of position of eustachian tubes to middle ear)nearly 100% will have this before 5 years oldrepeated infection may require placement of tubes in order to improve drainage