Lung Infections Flashcards
What is pneumonia?
Acute lower respiratory tract infection/infection of lung parenchyma causing inflammation of lungs which results in a build up of fluid in alevoli
Describe the pathophysiology of pneumonia
State the different types of pneumonia- giving a brief description of each
- Community acquired: developed before or within 48hrs of hosp admission and not been in hosp in last 14 days
- Hospital acquired (nosocomial): developed pneuomonia >48hrs after admission to hospital
- Aspiration pneumonia: developed pneumonia due to aspiration
- Pneumonia in the immunocompromised: pneumonia caused by atypical organism as pt is immunocompromised
*Can also classify based on infecting organism but often we classive based on source of infection
State the most common causative organisms of each of the following types of pneumonia:
- CAP
- HAP
- Aspiration pneumonia
- Pneumonia in immunocompromised
-
CAP
- Streptococcus pneumoniae
- Haemophilius influenza
- Morazella catarrhalis
- Staphlococcus aureus
- Some of the atypical organisms
-
HAP
- Strep pneumoniae
- Gram negative bacteria
- MRSA
- Pseudomonoas aeruginosa
- Staphylococcus aureus
-
Aspiration pneumonia
- Oral flora
- Anaerobes
-
Pneumonia in immunocompromised/opportunistic
- Pneumocystis jiroveci
- Aspergillus spp
- Cytomegalovirus
*CAN ALSO GET VIRAL PNEUMONIA
Alongside the 4 widely accepted categories of pneumonia mentioned previously, pneumonia can be also be caused by atypical organisms; state 3
- Mycoplasma pneumonia *MOST COMMON
- Chlamydia pneumoniae
- Legionella pneumophilia
State some risk factors for devleoping pneumonia
- Chronic respiratory disease (especially COPD)
- Smoking
- Age
- Lives in nursing home
- Immunocompromised
- Chronic alcohol use/abuse
- Contact with children
- Smoking
- Other chronnic comorbidities e.g. diabetes, CVD
- Poor oral hygiene
*Ones in bold= strong risk factors
State the symptoms of pneumonia
- Fever
- Cough
- Sputum production
- Dyspnoea
- Pleuritic chest pain
- Confusion (elderly)
- Rigors/night sweats
- Malaise
- Myalgia
- Anorexia
We have already said that pneumonia can be caused by atypcial organisms; for each of the following atypical organisms state some symptoms, risk factors and/or test results that may indicate that organism is the cause:
- Klebsiella
- Pseudomonas
- Legionella
- Mycoplasma
- PCP
- Chlamydia
Klebsiella
- Red current jelly like sputum
- Alcoholics & aspiration
Psuedomonas
- Green sputum
- Need stagnant mucus
Legionella
- Flu like symptoms precede dry cough
- Colonises water tanks at <60degrees (e.g. hotel air conditioning, hot water systems)
- D&V, hepatitis
- Hyponatraemia
- Urine antigen present
Mycoplasma
- Flu-like symptoms followed by a dry cough later on
- Cold agglutins
Pneumocystis jiroveci pneumonia
- Dry cough
- SoBoE (over few days become rapidly SOB on exertion)
- Treatment= co-Trimoxazole
Chlamydia
- Pharyngitis, hoarseness, otits followed by pneumonia
State what you might find on clinical examination of someone with pneumonia
- Pyrexia (although elderly can be hypothermic)
- Cyanosis
- Tachynnoea
- Tachycardia
- Hypotension
- Signs of consolidation:
- Dull percussion
- Increse vocal resonance
- Bronchial breathing
- Pleural rub
- Reduced chest expansion
- Reduced air entry
- Crackles
State the investigations you would do if you suspectd pneumonia, include:
- Bedside
- Bloods
- Imaging
*For each, justify why
Bedside
- Usual observations as always (attention SpO2)
- ?ABG: assess PaO2 and PaCO2 to guide O2 therapy
- Sputum sample: determine causative organism & antibiotic sensitivity
- Oropharyngeal swab: PCR for atypical organisms
- Urine culture: check for pneunomoccal and/or legionella antigens
Bloods
- FBC: WCC
- U&Es: need urea for CURB65
- LFTs: may be abnormal if basal pneumonia infiltrate liver. Hypoalbuminaemia also marker of severity. Chronic liver disease risk factor for complications
- CRP: infection
- ESR: infection
- Cold agglutins: check for mycoplasma
- Blood culture: determine causative organism
Imaging
- CXR: classical features of pneumonia. Rule out other causes
- ?Aspiration pleural fluid: if have pleural effusion. Can show causative organsis also. May need to drain
- ?Bronchoscopy or bronchoalevolar lavage: if symptoms persist after 6 weeks treatment
Discuss what you would find on CXR of someone with pneumonia
Consolidation will be seen; place varies dependent on subtype:
-
Lobar pneumonia
- Homogenous consodlidation of affected lobe
- Air bronchograms may be seen where consolidation is
-
Bronchopneumonia
- Patchy consolidation
-
Interstitial pneumonia
- Consolidation in ground glass appearnce in central distribution
May also pleural effusions, cavitations
Compare lobar, broncho and interstital pneumonia
*
State some common differentials for consolidation on a CXR
- Pneumonia
- TB (usually upper lobe)
- Lung cancer
- Lobar collapse (due to blockage of bronchi)
- Haemorrhage
We use the CURB65 score to assess the severity of pneumonia; explaint the CURB65 score
One point for each.
- 0-1= antibiotic/home therapy
- 2= hosp
- 3 or more= severe pneumonia- consider ITU
CURB65:
- Confusion: abbreviated mental test <8
- Urea: >7mmol/L
- Resp rate: >30/min
- BP: <90mmHg systolic, <60mm/Hg diastolic
- 65: aged 65 or over
*NOTE: CURB65 may underscore the young so use clinical judgement also
Brielfly/broadly discuss the immediate management of pneumonia
Always do ABCDE to make sure pt stable. Then main treatment plan is antibiotics in accordance with local guidelines (if CURB65 >2 give IV antibiotics)
Also consider:
- Oxgyen
- Fluids
- VTE prophylaxis
- Analgesia
- Consider ITU
Discuss what antibiotics you would use to treat CAP; include treatment for mild, moderate & severe disease
Mild
- Oral amoxicillin or oral doxycycline or oral clarithromycin (5 days)
Moderate
- Oral amoxicillin + oral doxycycline or oral clarithromycin (7-10 days)
Severe
- IV co-amoxiclav + IV doxycycline or IV clarithromycin (7-10 days)
Discuss what antibiotics you would use for HAP; include treatment for mild-moderate and severe
Mild-moderate
- Oral co-amoxiclav
Severe
NICE reccomends following IV antibiotics:
- Piperacillin/tazobactam
- Ceftazamide
- Ceftriazone
- Meropenem
Discuss the follow up management of someone with pneumonia
- Arrange follow up 6 weeks later and repeat CXR to ensure resolution
- Consider bronchoscopy in pts with persisting symptoms or abnormal radiological findings at 6 week follow up
- Other follow up tests:
- HIV test
- Immunoglobulins
- Pneumococcal IgG serotypes
- Haemophilius influenza b IgG
State some causes of non-resolving pneumonia
**Think CHAOS
- Complication: empyema, lunga abscess
- Host: immuncompromised
- Antibiotic: inadequete dose, poor oral absorption
- Organism: resistant or unexpected organisms not covered by antibiotics
- Second diagnosis: PE, cancer, organising pneumonia
What do we mean by atypical pneumonia?
Which abx do they respond to?
Pneumonia caused by an organism that can’t be cultured in the normal way or detected using a gram stain.
They don’t respond to penicillins. Can be treated with marcolides (e.g. clarithromycin), fluoroquinolones (e.g levofloxacin) or textracyclines (e.g. doxycycline)
State the 5 causes of atypical pneumonia
HINT: can remember by “Legions of psittaci MCQs”
- Legionella pneumophilia (Legionnaire’s disease)
- Chlamydia psittaci
- Mycoplasma pneumonia
- Chlamydydophilia pneumoniae
- Q fever (coxiella burnetii)
For each of the causes of atypical pneumonia, discuss:
- Where pt gets infection from
- Any symptoms/signs associated with infection by the atypical organism
Legionella pneumophilia (Legionnaire’s disease)
- Infected water supplies or air conditioning
- Can cause SIADH causing hyponatraemia
Chlamydia psittaci
- Infected birds
- MCQ pt often a parrot owner
Mycoplasma pneumoniae
- Milder pneumonia which can cause erythema multiforme rash and neurological symptoms in young pts
Chlamydydophilia pneumoniae
- Mild to moderate chronic pneumonia and wheeze in school aged children
Q fever (coxiella burnetti)
- Exposure to animals and their bodily fluids
- Typical MCQ is farmer with flu-like symptoms
For fungal pneumonia, discuss:
- Who usually presents in
- Most common causative fungi
- Presentation
- Treatment
- Immuncompromised; it is particularly important to consider in poorly controlled or new HIV with a low CD4 count
- Pneumocystis jiroveci (PCP)
- Present subtly with dry cough, SOBoE and night sweats
- Treatment: co-trimoxazole (trimethoprim/sulfamethoxazole) known by bran name Septrin
*NOTE: pts with low CD4 counts prescribed prophylactic oral co-trimoxazole to protect against PCP
State some potential complications of pneumonia
- Sepsis
- Pleural effusion
- Empyema
- Lung abscess
- Death
State 4 ‘at risk’ groups who are offered the flu vaccination
- Elderly >65yrs
- Chronic heart, liver, renal, lung conditions
- Immunosupressed
- Diabetes mellitus not controlled by diet
State 4 at risk groups who are offered pneumococcal vaccination
- babies
- people aged 65 and over
- anyone from the ages of 2 to 64 with a health condition that increases their risk of pneumococcal infection (generally same people who are eligible for flu vaccination)
- anyone at occupational risk, such as welders
What is tuberculosis?
Infection with Mycobacterium tuberculosis. It commonly involves the lungs and is communicable in this form, but may affect almost any organ system including the lymph nodes, central nervous system, liver, bones, genitourinary tract, and gastrointestinal tract.
Describe the pathogenesis of tuberculosis (recap from resp sem 3)
- Inhale MTB which deposits in alveoli. TB likes to deposit in fissures and subpleural spaces
- Macrophages try to remove MTB but cannot. Leads to activation of cell mediated immunity leading to emergence of macrophages with enhanced ability to kill MTB- takes about 6 weeks
- Macrophages then kill MTB in the alveoli forming a subpleural focus of tubercles called the ‘Ghon or Primary focus’. NOTE: tubercle= spherical granuloma with central caseating necrosis
- Some of the macrophages, which have engulfed TB, travel to a hilar lymph node and kill MTB causing a granuloma in lymph node aswell. The Ghon focus & enlarged hilar lymph node that has caseous granuloma also called the primary complex. This occurs over 3-8 weeks and causes an inflammatory reaction.
- Some TB bacilli may enter blood stream and heamatogenous spread can oocur leading to TB forming tubercles in other parts of lungs and extra-pulmonary sites
- There are then three options after this:
- Bacteria continues to multiply leading to progressive primary infection
- Bacteria is completely cleared (heals/self cure)
- Some TB bacilli persist in host without causing disease (TB bacilli could be in lungs or other extra-pulmonary sites) this can be reactivated in time causing secondary progressive/post primary TB
What is meant by miliary TB?
TB that has spread via blood both in lungs(leading to many discrete foci of granulomas in lungs) and to other organs in body; leading to millet seet appearance on CXR
State some risk factors for TB
- Past history of TB
- Known history of TB contact
- Born in country with high TB incidence
- Foreign travel to country with high TB incidence
- Immunosupression
*High TB incidence: Asia, Africa, South America, Eastern Europe