14. Pneumonias and Chest Infections Flashcards
What is the incidence of pneumonia per every 1000 adults?
How does the BTS (British Thoracic Society) define pneumonia?
What are some symptoms (localised and systemic), signs and radiographic changes of pneumonia?
Is pneumonia always infective?
5-11 cases. Highest incidence in extremes of age.
Symptoms and signs consistent with an acute lower respiratory tract infection associated with new radiographic shadowing for which there is no other explanation.
Symptoms: localised - cough + at least one other from: plueral pain, dyspnoea, tachypnoea. Systemic - sweating, fever, shivers, aches and pains and/or fever ≥38oc.
Signs: new + focal chest signs
Radiographic changes: new radiographic shadowing with no other explanation
No - e.g. eosinophilic pneumonia.
What are the top 3 organisms that cause pneumonia?
What are the top 3 oragnisms that cause pneumonia in nursing homes/hospitals?
What principle organisms cause pneumonia for each of the following patient factors:
a) Elderly
b) Chronic illness
c) Alcoholism
d) Immunodeficiency
Streptococcus pneumoniae, G-ve bacilli, H. influenzae. (pic) (But no pathogen ID’d = most common)
H. influenzae, G-ve and S. aureus. Decreased Legionella.
a) Elderly: increased incidence and mortality, decreased M.pneumoniae and Legionella, less classical presentation
b) Chronic illness: diabetes increases bacteraemic pneumococcal pneumonia. COPD increases H.influenzae and M.catarrhalis, sicker, same mortality.
Alcoholism: increased risk of most pathogens, consider aspiration
Immunodeficiency: medication e.g. immunosuppressive therapy, steroids - increases legionella. Chemo -> neutropenic sepsis and if no improvement consider fungal. HIV/AIDs - usually common causes. Consider TB, PCP etc.
What microbes are number 1 suspects for HAP (hospital acquired pneumonia)?
When pathogenic organisms are aspirated, they are ususally removed by defence mechanisms. What can these be overcome by?
List some lung defence mechanisms.
How might these become defected?
Gram -ves +/- Staph aureus. No need to cover Legionella.
Defect in host defence. Virulent organism. Overwhelming inoculum.
Filtration/deposition in upper airways. Cough reflex. Mucociliary clearance. Alveolar macrophages. Humoral and cellular immunity. Ocidative metabolism of neutrophils.
(pic)
What investigations in a patient with pneumonia could you perform to:
a) aid/confirm diagnosis?
b) stratify severity risk?
c) target therapy?
What are the 2 aims of microbiology with reference to lower respiratory tract infection?
What are urinary antigens, and how useful are they? What organisms are they available for?
a) Chest radiograph (within 4hrs), FBC (WCC usually >15x109/l), LFT, CRP (usually >100mg/l). E.g. eosinophil count for asthma?
b) U+Es, CRP, O2 sat/ABG
c) Blood and sputum cultures, pneumococcal urinay antigen, legionella urinary antigen + sputum culture, Mycoplasma PCR (sputum/throat swab), Chlamydophilia PCR/complement fixation.
1) ID pathogenic bacteria (microscopy)
2) Test sensitivity to abx (culture + sensitivites)
Can ID pts with actue infection. Highly sensitive (>80%) and specific (>95%). Rapid result. Remain +ve on tx. No info on antibiotic sensitivities. Only available for pneumococcal and legionella. NB use CFT (serology) for mycoplasma and chlamydophila. Influenza = nose/throat swab PCR.
What pathology appears on these 2 CXRs?
What chest radiograph changes are consistent with pneumonia?
L: RUZ and MZ consolidation
R: L pleural effusion
Consolidation (use term ‘shadowing’), lobar collapse, pleural effusion.
NB: no changes are pathologic for pneumonia…
Give tx and repeat CXR.
What pathology appears on these 2 CXRs?
What is the CURB65 criteria? What does it stand for?
L: RLL collapse
R: R pleural effusion with RMZ consolidation.
Clinical prediction rule for predicting mortality in community-acquired pneumonia (and infection of any site). Each risk factor measured scores 1 point, for a maximum score of 5. Use if struggling to dx pneumonia based on epidemiology, clinical presentation etc.
- *C**: new Confusion (AMTS (abbreviated mental test score) ≤ 8)
- *U**: increased Urea >7 mmol/L
- *R**: increased Respiratory rate ≥ 30/min
- *B**: decreased BP (SBP <90mmHg and/or DBP ≤ 60 mmHg)
- *65**: increased age ≤ 65
- Clinical judgement important, consider social factors + comorbidities.*
List some factors associated with increased mortality for a pt with pneumonia.
How would you manage a pt who had a CURB65 score of 0-1, 2, 3+, and 4-5?
Increased age, pre-existing comorbidities (esp COPD, renal disease and alcohol misuse), increased respiratory rate, confusion, decreased BP, hypoxaemia/respiratory failure, WCC >20 or < 4, bilateral/progressive CXR changes, +ve blood cultures, biochemical markers - CRP.
0-1: home tx, decreases risk of hospital acquired infection, VTE and mortality.
2: short admission, oral abx
3+: admit + urgent senior review
4-5: admit + critical care (ITU/HDU) review
O2 - aim for target sat, IV fluids, analgesia and DVT prophylaxis, chest physio/sitting out + nutritional support. Smoking cessation
Name abx likely to be effective against each of the major respiratory pathogens.
How is the correct drug chosen for lower respiratory tract infections? (When/where, route and how long?)
What is the preferred and alturnative tx for different severities of pneumonia (low, low but admission, moderate, high)?
What are the preferred medications for hospital acquired penumonia:
a) G- enteric bacilli
b) S. aureus
β-lactam (+ macrolide if moderate-severe): S.pneumoniae about 90% sensitive to penicillins and macrolides. Legionella and mycoplasma penicillin resistant but susceptible to macrolides (so give macrolide + β lactam).
When/where: immediatly after dx confirmed by CXR
Route: oral unless CURB65 ≥ 3, or unable
How long: mild 5/7, moderate-severe 7-10/7, atypicals 14-21/7
Preferred tx usually amoxycillin +/- clarithromycin. Alternative tx doxycycline. (pic)
a) Cefuroxime
b) Non-MRSA: flucloxacillin +/- rifampicin. MRSA: vancomycin or linezolid +/- rifampicin
Follow up at 6w. Why might pts fail to improve in the follow up?
What are some individual and society adverse consequences of abx?
What are some strategies for abx stewardship?
Incorrect dx or complicating condition. Unexpected/resistant pathogen. Impaired local/systemic immunity. Local/distant complications of CAP. Radiological resolution often lags behind clinical picture, slower in elderly + multilobar involement, so repeat CXR at 6/52 if no improvement and consider bronchoscopy and CT. May take up to 50 d to return to full activity.
Individual: C.diff, MRSA. Society: abx resistance - S.pneumoniae: penicillin resistance and macrolide resistance.
Ensure dx secure, discontinue if not appropriate, narrow spectrum if specific pathogen ID’d, IV -> oral switch, stop dates on drug charts.
Describe the vaccinations against (seasonal) influenza and pneumococcus.
What is atypical pneumonia and atypical pathogens?
What clinical/pathological/microbiological features differentiate atypical pathogens from ‘typical’?
(Pic)
‘Atypical pneumonia’ - don’t recommend its use, incorrectly implies distinctive clinical pattern. ‘Atypical pathogens’ defines infections caused by Mycoplasma pneumoniae, Chlamidophila pneumoniae, Chladmidophila psittaci, Coxiella burnetii. + legionella
Difficult to dx early in illness, resistant to β-lactams, replicate intracellulary, mixed reports regarding specific symptoms: Mycoplasma (younger and less systemic features, epidemics), C.pneumoniae (headaches, longer prodrome and older), C.psittaci (acquired from birds, only 20% have bird contact), C.burnetii (younger males, dry cough, high fever).
What things can cause legionella outbreak?
What 2 organisms are responsible for many winter epidemics?
Inhalation of aerosol form infected water source e.g. air con. Increase in summer - 50% related to foreign travel. Difficult to differentiate clinically: men, healthy younger pts, smokers, neuro/GI symptoms, less resp symptoms.
S. aureus. Influenza. Can be co-infected
