1.2 Community Acquired Pneumonia Flashcards
INITIAL INVESTIGATIONS
The initial investigations to be performed in suspected CAP include:
1. CXR (look for radiographic abnormalities e.g. patchy, lobar consolidation)
2. Blood tests (FBC, U+E, LFTs, CRP)
3. ___________________ (oxygenation status)
4. Microbiological investigations (sputum cultures, blood cultures, urine antigen tests for ________________ and _____________)
WCC would be raised in infections; systemic infections may cause dehydration (abnormal kidney function) → some labs use _____________ (instead of CRP; more specific))
Arterial blood gases;
Legionella pneumophila;
Streptococcus pneumoniae;
procalcitonin levels
CLINICAL PRESENTATION
On CXR, infiltrates are seen in ____________________, while there are no radiographic infiltrates in URTIs:
Common signs
- Dyspnoea (SOB)
- Cough, sputum production
- Fever
- Crackles, wheeze
Less common signs
- Changes in mental state
- Bronchial breathing
- Reduced breath sounds
- Normal (asymptomatic)
pneumonia (consolidation/increased opacification)
- Raised urea: indicates __________________
* Raised white cell count: increased in response to ____________
dehydration (more likely to have more severe pneumonia) ;
infection
EPIDEMIOLOGY
There is a high incidence and mortality rate (25.45% > 90yo) with increasing age:
Risk factors • Demographic and lifestyle factors - Extremes of age (< 2 years or > 65 years) - Cigarette smoking - Excess alcohol consumption
• Social factors
- Contact with children aged ___________
- Poverty, overcrowding
• Medications
- Inhaled corticosteroids, immunosuppressants (e.g. steroids)
- ______________________
• Medical history
- COPD, asthma, previous pneumonia
- Heart disease, liver disease, diabetes mellitus, HIV, malignancy
• Specific risk factors for certain pathogens
- Geographical variations
- Animal contact
- Healthcare contacts
< 15 years;
Proton pump inhibitors (PPIs)
The most common pathogens which cause CAP include:
Typical
- ________________
- _________________
- ________________
Atypical
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Legionella pneumophila (Gram-negative)
* Staphylococcus species are also common causes of CAP.
Streptococcus pneumoniae (GNC);
Haemophilus influenzae (GNCB);
Moraxella catarrhalis (GNC – diplococcus)
Typical VS Atypical Pneumonia
Typical
- productive cough (sputum)
- acute onset
- extrapulmonary features not usually present
- leukacytosis
- x ray: _______ changes
- diagnosis: ______________
Atypical
- non productive cough
- insidious onset
- extrapulmonary features: _________________
- no leukocytosis, hyponatraemia
- x ray: _____________-
diagnosis: ______________
*Atypical bacteria are not covered by standard penicillin antibiotics (require usually __________ to treat).
lobar;
sputum/ blood cultures;
headaches, N/V/D,
Diffuse patchy;
Atypical serology ;
macrolides
Additional considerations for the causative organism for CAPs include:
• History of diabetes mellitus: consider _________________
• Preceding influenza: consider ___________________
• Alcoholic or high likelihood aspiration: consider ________________
• Prolonged cough (> 2 weeks) with weight loss: consider _______________
Klebsiella and melioidosis (Burkholderia);
Staphylococcus aureus and Streptococcus pneumoniae;
anaerobic cover;
tuberculosis
ANTIBIOTIC THERAPY
As there are no tests that can give rapid information about the causative pathogen of CAP, the initial choice of treatment must be empirical (based on local guidelines):
Factors for choice of antibiotic therapy
• Age (different pathogens in elderly and children)
• Comorbidities
• Severity of disease (give ______________ for severe)
• Patient allergies / antibiotic intolerance
• Previous pathogens / colonisation
• Local epidemiology / resistance
______________ are commonly given for first-line treatment (with or without macrolides for atypical pathogen coverage):
• Local guidelines within hospitals may differ (alternative agents for penicillins include _________________)
• Time to antibiotic administration is crucial (especially for those with severe disease/sepsis → as soon as possible)
o Every hour of delay in septic shock results in 7.9% reduction in survival
• Duration of treatment: typically 1 week (3 – 7 days for mild to moderate pneumonia
broad spectrum;
Aminopenicillins (ampicillin/amoxicillin);
cephalosporins and quinolones
COMPLICATIONS
Patients with pneumonia may develop parapneumonic effusions (fluid accumulation in __________) and empyema (pus in __________):
• Complicated parapneumonic effusions refers to when ______
• Usual pathogens causing empyema include: ________________(most common; 50%), Staphylococcus aureus, Gram-negative aerobes and anaerobes (often mixed picture with 2 or more pathogens present)
• Treatment: ________, _________, ______
pleural space;
pleural space;
acidic fluid accumulates;
Streptococcus spp.
chest tube drainage, surgery (cleaning the pleural cavity), long-term antibiotics
They may also present with pulmonary abscesses (less frequent than parapneumonic effusions and empyema):
• Usual pathogens causing pulmonary abscesses include: ___________________
• Complications: metastatic infection (spreads throughout body including bloodstream) → ________________ (cavities lying on pulmonary vessels)
• Treatment: long-term antibiotic therapy and surgical treatment (if possible)
*Complications of CAP may be severe, and treatment failure requires additional investigation and broader antibiotic therapy.
Staphylococcus aureus, Klebsiella pneumoniae, tuberculosis, anaerobes and Streptococci;
massive haemoptysis
Viral pneumonia is less common than bacterial pneumonia in adults:
Common
- __________
- __________ (more of paeds)
- Adenovirus
Rarer (newer)
- SARS/MERS coronaviruses
Influenza A/B;
Respiratory syncytial virus (RSV)
INFLUENZA VIRUSES The membrane envelope of the influenza viruses contains ______________ (9 subtypes) and _______________ (15 subtypes) glycoproteins involved in entry and release:
• Possesses a ______________ genome
• Cause of many epidemics throughout history (e.g. H1N1 Spanish flu, H2N2 Asian flu, H3N2 HK flu, H5N2 Avian flu) → population is never immune due to antigenic drift and antigenic shift (refer to M1 IMS notes)
neuraminidase;
haemagglutinin
single-stranded RNA
H5N1 (more commonly known as Avian/bird flu) is a highly infective pathogen which is able to cause disease in multiple species (humans, birds, cats, poultry):
• High mortality rate of 50%; causing ____________________ (including cough, shortness of breath, muscle pain, abdominal pain, vomiting, diarrhoea)
• ____________ (20%) and ___________ (50 – 80%) may also occur
URTIs, LRTIs and GI symptoms;
Renal failure;
pancytopenia
H1N1 (more commonly known as swine flu) was a pathogen which caused a global pandemic in 2009 – 2010, with a substantial number of people infected and hospitalised:
• Many fatal confirmed influenza deaths between 2009 to 2011 in the UK were due to the 2009 strain of H1N1 influenza A virus
• Risk factors: non-white ethnic backgrounds, mild asthma, pregnant women, <5 yo, ITU/HDU (even those with no underlying health problems had high risk)
• Treatment: ___________________
early antiviral therapy (within 48 hours of symptom onset)
CORONAVIRUSES (SARS & MERS)
There are two known human coronaviruses (____________ viruses) which may cause SARS (severe acute respiratory syndrome):
• Widespread in domestic animals (enteric, lung, liver etc.) and are highly virulent in tissue cultures (Vero cells) with a completely novel genome
• Presentation: fever (>38°C), cough or breathing difficulty, death (from ________________), infiltrations on CXR, pneumonia, acute respiratory distress syndrome (ARDS), diarrhoea, desaturation
• Lab results: SARS coronavirus (virus cultures, PCR, antibodies)
• Virus excretion begins at or before the onset of illness (from stools from day 3 and from respiratory tract from day 5):
o Avoid: routine hospitalisation, nebulisers, ventilators and trips to X-rays (provided route for transmission of virus)
• Rapid global travel facilitated the spread of SARS, and the enclosed living and modern healthcare system was exploited for transmission
MERS (Middle Eastern Respiratory Syndrome) was first reported in Saudi Arabia in 2012, and is caused by the novel coronavirus MERS-CoV (same genus as SARS-CoV):
• Leads to _____________________ (with high mortality rate: 63/149)
large RNA
unexplained acute respiratory illness;
severe acute pneumonia and renal failure
