Pneumonia SR Flashcards
Features of pneumonia in the elderly
RR increase
crackles
consolidation
fevers/chills
*lower areas of lung
Bacteria with capsules (can’t be phagocytosed)
Streptococcus pneumoniae Staphylococcus aureus Haemophilus influenzae Neisseria meningitidis Escherichia coli
Common causes of pneumonia
Streptococcus pneumoniae Haemophilus influenzae Staph aureus Enterobacteriaceae Legionella pneumophila (rare) Mycoplasma pneumoniae Chlamydophilia pneumoniae Aspiration Influenza viruses
Features of strep pneumoniae
- alpha-haemolytic streptococcus
2. colonizes nasopharynx of 5-10% of adults, 20-40% of children
Pneumococcal virulence
- pneumococcal surface protein A - binds to epithelial cells and also prevents deposition of C3b
- PspC prevents activation of complement cascade
- pili contribute to colonisation and cytokine production (TNFa) during invasion
- choline binding protein - binds Ig receptor on epithelial cells to allow transport into cell
- pneumolysin (toxin) lyses neutrophils and epithelial cells
- polysaccharide capsule prevents phagocytosis and complement deposition
Pneumonia investigations
1. PRIMARY CXR (if none no antibiotics) 2. Sputum culture (only on admission) 3. Nasopharyngeal swab (if admitted) - if viral shown on PCR stop antibiotics 4. blood cultures 5. urine ICT (immunochromatographic test) 6. serology 7. CT chest/ bronchoscopy
Treatment
- Antibiotics! reduce duration of illness and risk of death
- Penicillin resistance is increasing - mediated by altered PBP/transpeptidace which reduces penicillin binding affinity
- *oral dosing inadequate. IV dosing okay - important in treating menigitis caused by s. pn
- **penicillin resistance is associated with resistance to other antibiotics - quinolones, recently developed macrolides, ketolides
Ribosome targets
50S transpeptidation -
1. macrolides eg erythromycin A, azithromycin, clarithromycin,
(broad spectrum, limited activity against gram negative bacteria, active against streptococci, staphylococci and other causes of pneumoniae, tratment of chlamydia)
- lincosamides
50S peptidyl transferase - chloramphenicol
30S initiation - aminoglycosides
30S tRNA binding - tetracyclines
Macrolides adverse effects
GIT upset
Sudden death
drug-drug interactions
Empiric therapy
A medical term referring to the initiation of treatment prior to determination of a firm diagnosis.
Community acquired
Mild (can stay home) - doxycycline, amoxycillin 500mg tds
Moderate (often in hospital)
amoxycillin 1g oral/IV Q6H AND roxithromycin 300mg daily OR doxycycline 200mg on day 1 then 100mg daily
Very sick (ICU) amoxycillin/clavulanic acid 1.2gm IV Q8H and erythromycin 1g IV Q6H or moxifloxacin 400mg IV daily
Health care associated pneumonia
cefuroxime 1.5gm IV Q8H +/- gentamicin IV daily
Bronchitis
Viral illness
Antibiotics not beneficial
Treatment for cough include NSAIDS, sedating antihistamines, chlorpheniramine
- Influenza
- Adenovirus
- other viruses
- measles
- bordetella pertussis
- chlamydia/mycoplasma