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Micro - Streptococci (iii) (Enterococci (risk factors (surgery, malignancy…
Micro - Streptococci (iii)
S Pneumoniae
diplococci
in nasopharynx of 5-10% of adults, 20-40% of children (mediated via adhesin)
over 90 serotypes based on polysaccharides capsule
vaccines for some
in childhood vaccine programme
also for adults > 65 y/o + high risk groups (e.g. splenectomy/congenital asplenia)
catalase -ve
optochin sensitive
invasion promoted by cell wall, cytotoxin pneumolysin (both activate complement + cause CK release), adhesin, capsule (antiphagocytic
risk factor = immunocompromisation
! antibiotic resistance
droplet spread
causes
pneumococcal pneumonia
pleuritic chest pain
dyspnoea
purulent sputum
usually lobar, but can spread to bronchus (esp in elderly)
influenza = major predisposing factor
complications
lung abscess (pus collection in pathological cavity)
empyema (pus collection in physiological cavity)
parapneumonic effusion (pleural effusion arising from pneumonia)
sinusitis
esp paranasal sinuses
usually preceded by upper RTI
in all ages
otitis media
usually preceded by upper RTI
esp in young children
pneumococcal meningitis
leading cause of meningitis in adults
gets to CNS via bacteraemia, chronic ear/sinusinfection, or head trauma
BSI
in 25-30% of patients with pneumococcal pneumonia
may accompany pneumococcal meningitis
rarely occurs in sinusitis/otitis media
Enterococci
18 species
E Faecium + E Faecalis most common
low virulence, part of bowel flora
previously known as grown D strep
facultative anaerobes
some alpha + some beta-haemolytic
can grow in presence of bile salts (i.e. on MacConkey)
protein + carb factors enable binding to cells
antibiotic resistance can be intrinsic or acquired
e.g. VRE
transmitted via hands, environment, contaminated H2O/food
risk factors
surgery
malignancy
burns
trauma
recent cephalosporins/aminoglycosides
prolonged hospitalisation (esp ICU)
cause UTIs (esp cather-related), endocarditis, BSI, wound infections, intra-ab infections