5. Pneumonia Flashcards
Define Pneumonia.
It is the proliferation of microbial pathogens at the alveolar level in a host and the host’s response to those pathogens.
What is the main characteristic of a patient with Pneumonia?
Consolidation of Lobes of the Lung (Alveoli are filled with inflammatory exudate, WBCs and bacteria)
Classify Pneumonia.
It can be classified according to these criterias :
- Anatomical Pattern (Lobar and Bronchopneumonia)
- Clinical Circumstances
- Host’s Reaction
- Etiological Agents
- Sources of Infection
State the different clinical circumstances that may lead to Pneumonia.
- Primary (Healthy person)
2. Secondary (Local/Systemic defects in host’s defence)
State the different host’s reaction that may occur in Pneumonia.
It could be fibrinous or suppurative, depending on the dominant component of the exudate.
State the etiological agents that may lead to Pneumonia.
- Bacterial
- Viral
- Fungal
- Others
Name the bacterial aetiological agents that may lead to Pneumonia.
- Streptococcal pneumonia
- TB pneumonia
- Staphylococcus aureus
Name the viral aetiological agents that may lead to Pneumonia.
- Measles
- Influenza
- RSV
- Adenovirus
- Coronavirus
Name the fungal aetiological agents that may lead to Pneumonia.
- Cryptococcus neoformans
- Candida sp.
- Aspergillus
Name the other aetiological agents that may lead to Pneumonia.
- Mycoplasma pneumoniae
2. Pneumocystis jiroveci
State the different sources of infections that may lead to Pneumonia.
- Community-acquired pneumonia (CAP)
- Hospital-acquired pneumonia (HAP)
- Ventilator-acquired pneumonia (VAP)
How does an infection occur in the lungs and give examples.
- Aspiration of content from the Oropharynx (Ex; Saliva)
- Hematogenous Spread (Ex; Pathogens from Tricuspid Endocarditis)
- Contiguous extension (Ex; Infected Pleural/Mediastinal Space)
State the risk factors that may lead to Pneumonia.
- Age
- Co-morbidity (Diabetes, Asthma, COPD, Bronchiectasis)
- Immunosuppresion
- Neoplasia
- Neurological disorders
- Alcohol/Tobacco consumption
- Other various lifestyle factors
Define Community-acquired Pneumonia.
It is pneumonia which develops in a healthy person outside the hospital or in a person who has been in the hospital for less than 48 hours.
State the bacterial aetiological agents causing CAP.
- Typical Bacterial Pathogens :
- Strep. pneumoniae
- Haemophilus influenzae
- Staphyloccoccus aureus
- Gram negative bacili (Klebsiella pneumoniae, Pseudomonas aeruginosa)
- Atypical Bacterial Pathogens :
- Mycoplasma pneumoniae
- Chlamydophilia pneumoniae
- Legionella pneumoniae
- Chlamydia psittaci (commonly found in birds)
- Coxiella burnetti (commonly found in cattle/cats)
What are the symptoms seen in a patient with CAP?
- High fever with chills
- Cough
- Rusty/Mucopurulent sputum
- Dyspnoea
- Pleuritic Chest Pain
What the signs elicited in a patient with CAP?
- Fever
- Tachycardia
- Tachypneoea
- Cyanosis
- Hypotension
What is observed in the respiratory examination of a patient with CAP?
- Decreased respiratory (chest) movements, exclusively in the affected lobe.
- Impaired note on percussion (woody dull note)
- Tubular bronchial breath sounds
- Increased vocal resonance
- Aegophony
- Crepitations
- Pleural effusion/rub
What is observed in the respiratory examination of a patient with CAP?
Elevated WBC count
State the complications that might occur in a patient with CAP.
- Lung abscess
- Para-pneumonic effusions
- Empyema
- Sepsis
- Metastatic infections (Meningitis, Endocarditis, Arthritis)
- ARDS
- Respiratory Failure
- Circulatory Failure
- Renal Failure
- Multiorgan Failure
How would you handle a suspected case of Pneumonia?
- Obtain relevant details from the history
- Check for signs and symptoms
- Conduct blood investigations
- Conduct a Chest X-Ray
- Send a sputum sample to the lab for Culture and Gram Staining
- Other tests : Chest CT, Blood culture, Antigen test, Serology, Bronchoscopy, Bronchoalveolar lavage, PCR.
What is to be expected in a Chest X-Ray of a patient with Pneumonia?
Homogenous opacity is observed, indicating consolidation. Sometimes, a cavity (no opacity) may be present.
What are the goals of treatment in a CAP patient?
- Selection of appropriate antibiotics
2. Treat the asso. co-morbidities and it’s complications
What are the ‘Severity of Illness’ scoring methods used in a case of Pneumonia?
- CURB-65
2. Pneumonia Severity Index
Explain about CURB-65.
CURB-65 Criteria (If a patient meet 2 or more criterias, hospitalization is required)
- Confusion
- Urea : > 7 mmol
- Respiratory Rate : > 30
- Blood Pressure : Low (SBP<90/DBP>60)
What is the general approach you’d take to treat a patient with CAP?
- Check for adequacy of respiratory function
- Administer Humidified Oxygen if hypoxemia is present
- Administer Bronchodilators (Albuterol) if bronchoconstriction is present
- Chest physiotherapy with postural drainage
- Provide adequate hydration if necessary
- Administer Expectorants (Guaifenesin) if necessary
- Administer Analgesics for Pleuritic Chest Pains
How would you administer the anti-microbials in a CAP case?
Initially, apply empirical use of Broad Spectrum antibiotics. After the culture and sensitivity report is confirmed, apply Narrow Spectrum antibiotics to target specific pathogens.
What drugs are preferred in a CAP case due to Staph. pneumonia (MSSA)?
Flucloxacillin 1-2g Q6H IV + Clarithromycin 500mg Q12H IV
What drugs are preferred in a CAP case due to Atypical Bacterial Pneumonia (MSSA)?
Erythromycin 500mg Q6H oral/IV +/- Rifampicin 600mg Q12H IV for severe cases
What would you prescribe a CAP patient who has been previously healthy and has no antibiotic use in the past 3 months?
A Macrolide (Clarithromycin/Azithromycin) or Doxycycline (100mg PO b.i.d)
What would you prescribe a CAP patient who has presence of co-morbidities or anti-biotic use in the past 3 months?
- Respiratory Fluoroquinolone (Moxifloxacin, Gemifloxacin, Levofloxacin)
- Beta-Lactam AB (High Dose of Amoxicillin, Amoxicillin/Clavulanate + a Macrolide)
What would you prescribe a CAP patient who is admitted in the ICU?
Beta-Lactam AB + Azithromycin/Fluoroquinolone
Ex :
- Co-amoxiclav 1.2g Q8H IV
or
- Ceftriaxone 2g IV daily
or
- Cefuroxime 1.5g Q8H IV
+ Typical bacterial ‘cover’ : Tetracycline, Macrolides or FQs
Define ‘Hospital-acquired pneumonia’ (HAP).
It is a pneumonia that occupant after 48 hours of hospitalisation (due to other reasons) and which was not incubating at the time of admission.
When is HAP suspected?
In the presence of a new/progressive radiographic infiltrate on the X-Ray + at least 2 of these 3 clinical features (Fever : >38 degrees, Leucocytosis/Leukopenia, Purulent secretions)
State the symptoms seen in a patient with HAP.
- New onset of fever
- Cough with purulent sputum
*symptoms may be obscured by underlying diseases
State the signs elicited in a patient with HAP.
- Fever
- Tachycardia
- Tachypnoea
What is observed in a respiratory examination of a HAP patient?
- Impaired percussion notes
- Tubular breath sounds
- Crepitations
What investigations would you carry out to confirm your diagnosis of HAP?
- Blood count (leucocytosis w. neutrophilia)
- Chest X-Ray (Patchy, non-lobar infiltrates, cavitations, pleural effusion, empyema)
- Sputum culture and sensitivity test
- Blood culture
- ABG test
Define ‘Ventilator-acquired pneumonia’ (VAP).
It is the pneumonia that occurs in 48-72 hours after endotracheal intubation.
State the pre-disposing factors of HAP and VAP.
- Close approximation with patients
- Intimate exposure of patients to hospital personnel
- Unusual reservoirs of microbes
- Microbes with antibiotic resistance
- Host factors : underlying illness, prolonged antibiotic use, immunosuppression, impaired mental status (drugs/coma)
- Invasive hospital procedures : Endotracheal intubation, Bronchoscopy, Tracheostomy
State the sources of infection for HAP and VAP.
- Environmental : Aspergillus (air), Legionella (water), Gram -ve bacteria (food), S. aureus/RSV (fomites)
- Devices : Endotracheal tubes, Suction Catheters, Bronchoscope, Respiratory therapy equipment, Nasogastric Tubes
- Other patients
- Hospital personnel
State the common modes of transmission of infections for HAP and VAP?
- Aspiration
- Hematogenous dissemination
- Inhalation
- Direct inoculation into airways
State the complications seen in HAP and VAP cases?
- Lung abscess
- Cavitation
- Pleural Effusion
- Empyema
Name the bacterial agents that cause HAP and VAP.
- Gram -ve bacilli : Pseudomonas aeruginosa, Enterobacteriaeae
- Enteric G-ve organisms : E.coli, Klebsiella sp., Proteus sp., Seratio marcescens, H. influenzae
- Staph. aureus (MSSA/MRSA)
- Anaerobic bacteria
- Haemophilus influenzae
- Strep. pneumoniae
- Legionella sp.
When is HAP/VAP due to Pseudomonas aeruginosa commonly seen?
- Prolonged ICU stay
- Prolonged steroid/antibiotic use
- Structural lung damage patients
When is HAP/VAP due to MSSA/MRSA is commonly seen?
- Coma
- Head injury
- Diabetes
- Renal failure patients
When is HAP/VAP due to anaerobic bacteria commonly seen?
- Patients with recent abdominal surgery
2. Aspirations
When is HAP/VAP due to Legionella sp. commonly seen?
Patients who use high doses of Steroids
What drugs would you prescribe for a patient with HAP/VAP due to Gram -ve bacilli?
- 3rd gen. Cephalosporins
2. Aminoglycosides
What drugs would you prescribe for a patient with HAP/VAP due to Pseudomonas aeruginosa?
- Ceftazidime
- Cefipime
- Piperacillin
- Ciprofloxacin
What drugs would you prescribe for a patient with HAP/VAP due to Staph.aureus?
- Linezolid
2. Vancomycin
What drugs would you prescribe for a patient with HAP/VAP due to anaerobes?
- Metronidazole 500mg Q8H IV
2. Clindamycin
What is the commonly used scoring method for HAP and VAP?
CLINICAL PULM. INFECTION SCORE (CPIS)
- Temperature
- WBC count
- Oxygenation
- Purulent secretion
- Chest X-Ray infiltrates
