pneumonia Flashcards
definition of pneumonia
Infection of distal lung parenchyma.
categorised as:
- community acquired/hospital acquired/nosocomial
- aspiration pneumonia, pneumonia in the immunocompromised
- typical and atypical (mycoplasma, chlamydia, legionella)
pneumococcal pneumonia
The commonest bacterial pneumonia.
Affects all ages, but is commoner in the elderly, alcoholics, post-splenectomy, immunosuppressed, and patients with chronic heart failure or pre-existing lung disease.
Fever, pleurisy, herpes labialis.
CXR shows lobar consolidation. If mod/severe check for urinary antigen.
amoxicillin, benzylpenicillin, or cephalosporin.
staphylococcal pneumonia
May complicate influenza infection or occur in the young, elderly, intravenous drug users, or patients with underlying disease, eg leukaemia, lymphoma, cystic fibrosis (CF).
It causes a bilateral cavitating bronchopneumonia.
flucloxacillin ±rifampicin, MRSA: contact lab; consider vancomycin.
klebsiella pneumonia
rare. Occurs in elderly, diabetics, and alcoholics.
Causes a cavitating pneumonia, particularly of the upper lobes, often drug resistant.
cefotaxime or imipenem.
pseudomonas pneumonia
A common pathogen in bronchiectasis and CF.
causes hospital-acquired infections, particularly on ITU or after surgery.
anti-pseudomonal penicillin, ceftazidime, meropenem, or ciprofloxacin + aminoglycoside. Consider dual therapy to minimize resistance.
mycoplasma pneumonia
Occurs in epidemics about every 4yrs
flu-like symptoms (headache, myalgia, arthralgia) followed by a dry cough
CXR: reticular-nodular shadowing or patchy consolidation often of one lower lobe, and worse than signs suggest.
PCR sputum or serology. Cold agglutinins may cause an autoimmune haemolytic anaemia.
Complications: Skin rash (erythema multiforme), Stevens–Johnson syndrome, meningoencephalitis or myelitis; Guillain–Barré syndrome.
Clarithromycin (500mg/12h) or doxycycline (200mg loading then 100mg OD) or a fluroquinolone (eg ciprofloxacin or norfloxacin).
legionelaa pneumophilia
Colonizes water tanks kept at <60°C (eg hotel air-conditioning and hot water systems) causing outbreaks.
Flu-like symptoms (fever, malaise, myalgia) precede a dry cough and dyspnoea. Extra-pulmonary features in-clude anorexia, D&V, hepatitis, renal failure, confusion, and coma.
CXR shows bi-basal consolidation. Blood tests may show lymphopenia, hyponatraemia, and deranged LFTS. Urinalysis may show haematuria.
diagnosis: urine ag/culture
fluoroquinolone for 2–3wks or clarithromycin
10% mortality
chlamydophilia pneumoniae
The commonest chlamydial infection. Person-to-person spread,
biphasic illness: pharyngitis, hoarseness, otitis, followed by pneumonia.
Diagnosis: Chlamydophila complement fixation test, PCR invasive samples.
Doxycycline or clarithromycin.
chlamydophilia psittaci
Causes psittacosis, an ornithosis acquired from infected birds (typically parrots).
headache, fever, dry cough, lethargy, arthralgia, anorexia, and D&V. Extra-pulmonary features are legion but rare, eg meningo-encephalitis, infective endocarditis, hepatitis, nephritis, rash, splenomegaly.
CXR shows patchy consolidation.
Diagnosis: Chlamydophila serology
doxycycline or clarithromycin.
viral pneumonia
Influenza commonest
but ‘swine flu’ (H1N1) is now considered seasonal and covered by the annual ‘flu vaccine. Others: measles, CMV, varicella zoster.
avian influenza
- if fever (>38°C), chest signs or consolidation on CXR, or life-threatening infection, and contact with poultry or others with similar symptoms
- D&V, abdominal pain, pleuritic pain, and bleeding from the nose and gums are reported to be an early feature in some patients
- H7N9 and H5N1
- diagnosis: Viral culture ± reverse transcriptase-PCR with H5 & N1 specific primers.
- Ventilatory support + O2 and antivirals may be needed. Most viruses are susceptible to oseltamivir, peramivir, and zanamivir.
- Nebulizers and high-air flow O2 masks are implicated in nosocomial spread.
pneumocystis pneumonia
in the immunosuppressed (eg HIV).
dry cough, exertional dyspnoea, low PaO2, fever, bilateral crepitations.
CXR may be normal or show bilateral perihilar interstitial shadowing.
Diagnosis: Visualization of the organism in induced sputum, bronchoalveolar lavage, or in a lung biopsy specimen.
High-dose co-trimoxazole, or pentamidine by slow IVI for 2–3 weeks. Steroids are beneficial if severe hypoxaemia.
Prophylaxis is indicated if the CD4 count is <200≈106/L or after the 1st attack.
aetiology of CAP
may be primary/secondary due to underlying lung disease
Streptococcus pneumoniae(70%),
Haemophilus influenzae and Moraxella catarrhalis(COPD) ,
Chlamydia pneumonia and Chlamydia psittaci (contactwith birds/parrots),
Mycoplasma pneumonia (periodic epidemics),
Legionella (anywhere with air conditioning),
Staphylococcus aureus (recent influenza infection, IV drug users),
Coxiella burnetii (Q fever, rare),
TB (may present as pneumonia).
Viruses including influenza account for up to 15%.
flu might be complicated by community-acquired MRSA pneumonia
aetiology of HAP
defined as >48hr after hospital admission
staph aureus or gram -ve enterobacter especially in COPD (Pseudomonas, klebsiella, bacteroides, clostridia)
anaerobes (aspiration pneumonia)
aetiology of aspiration pneumonia
Those with stroke, myasthenia, bulbar palsies, reduced consciousness (eg post-ictal or intoxicated), oesophageal disease (achalasia, reflux), or poor dental hygiene risk aspirating oropharyngeal anaerobes.
pneumonia aetiology in immunocompromised
Strep. pneumoniae, H. influenzae, Staph. aureus, M. catarrhalis, M. pneumoniae, Gram Ωve bacilli and Pneumocystis jirovecii (P carinii)
Other fungi, viruses (CMV, HSV), and mycobacteria.
RF for pneumonia
age - very young or very old
smoking
alcohol
pre-existing lung diseae
immunodeficiency
contact with pneumonia
