2. Introduction
2
Pneumonia is an infection of the pulmonary
parenchyma
Common cause of significant morbidity and mortality
can be classified as:-
Community acquired (CAP)
Hospital acquired (HAP)
Ventilator-associated pneumonia (VAP)
Healthcare-associated pneumonia (HCAP)
3. Pathophysiology
3
Results from the proliferation of microbial pathogens at the
alveolar level and the host’s response to those pathogens
Microorganisms gain access to the lower respiratory tract
in several ways;
Aspiration from oropharynx
Inhalation as contaminated droplets
Rarely via hematogenous spread
Risk factors
Intrinsic factors- host factors
Extrinsic factors- exposure to a causative agent, pulmonary
irritants, or direct pulmonary injury
4. 4
Intrinsic factors
Age
Loss of protective upper
air way reflexes
Altered mental status
Endotracheal intubation
Immunosuppression
Dysfunction of local
defense mechanisms
Smoking
COPD, bronchiectasis,
CF
Tumors
Chronic periodontitis
Extrinsic factors-
virulence factors
C. pneumonia produce
a cilostatic factor
M. pneumonia can
shear off cilia
Influenza virus markedly
reduces tracheal mucus
velocity
S. pneumonia and N.
meningitidis produce
proteases that can split
secretory IgA
5. Pathology
5
Pneumonia evolves through 4 interrelated series of pathologic changes
1. Alveolar edema
The presence of a proteinaceous exudate and bacteria
2. Red hepatization phase
Erythrocytes and neutrophils predominate
Bacteria are occasionally seen
3. Gray hepatization phase
RBCs are degraded
neutrophils predominate, and bacteria have disappeared
Corresponds with successful containment of the infection and improvement in
gas exchange
4. Resolution phase
The debris of neutrophils, bacteria, and fibrin are cleared
6. Community-Acquired pneumonia
(CAP)
6
Etiology – can be caused by bacteria, fungi, viruses, and
protozoa
“Typical” bacterial causes
S. pneumonia- the most common cause
H. influenza
Pseudomonas
“Atypical” causes
Mycoplasma pneumonia
Chlamydia pneumonia
Legionella
Inflenza viruses
Adenoviruses
Respiratory syncytial virus
8. Clinical manifestations
8
Vary from indolent to fulminant
Fever, tachypnea,tachycardia, chills, and sweating
Cough with mucoid, purulent, or blood-tingled sputum
Pleuritic chest pain
Nausea, vomiting, and/or diarrhea
Fatigue, headache, myalgia, and arthralgia
9. 9
Use of accessory muscles
Increased or decreased tactile fremitus and dull
percussion note
Crackles, BBS, and/or pleural friction rub
The clinical presentation may not be so obvious in the
elderly, who may initially display new-onset or
worsening confusion
Severely ill patients may have septic shock and
evidence of organ failure
10. Hospital-acquired pneumonia
(HAP)
10
Hospital-acquired (or nosocomial) pneumonia (HAP) is
pneumonia that occurs 48 hours or more after admission and did
not appear to be incubating at the time of admission.
Ventilator-associated pneumonia (VAP) is a type of HAP that
develops more than 48 to 72 hours after endotracheal intubation.
Healthcare-associated pneumonia (HCAP) is defined as
pneumonia that occurs in a non-hospitalized patient with
extensive healthcare contact, as defined by one or more of the
following:
Intravenous therapy, wound care, or intravenous chemotherapy
within the prior 30 days
Residence in a nursing home or other long-term care facility
Hospitalization in an acute care hospital for two or more days
within the prior 90 days
Attendance at a hospital or hemodialysis clinic within the prior 30
days
11. Diagnosis
11
Chest X-ray
Lobar Vs bronchopneumonia
May suggest etiologic diagnosis- eg-
pneumatoceles suggest infection with S. aureus
Risk factors for increased severity- cavitation or
multilobar involvement
Complications- eg- pneumothorax
14. Etiologic diagnosis
14
Clinical diagnosis with radiologic support usually suffices to
diagnose most patients with pneumonia
Treatment directed at a specific pathogen is not generally
superior to emperical therapy based on clinical amd
radiologic diagnosis
Indications for etiologic diagnosis
Patients with severe CAP requiring ICU admission
Patients with severe HAP/VAP
Suspicion of pathogens with important public safety
implications
M. tuberculosis
Legionella
Influenza virus
Community aquired MRSA (CA-MRSA)
Agents of bioterrorism
15. 15
Gram’s stain and culture of sputum
Adequate sample
>25PMNLs and <10 squamous epithelial cells per low-power field
Sensitivity and specificity are highly variable
Blood cultures
Yield-very low- 5-14%
Antigen tests
Urine antigen tests for pneumococcal and legionella
Have high sensitivity and specificity
Polymerase chain reaction(PCR)
serology
17. Severe pneumonia
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Assessment of severity is important to decide the
place of care of the patient
Patients with severe pneumonia should be
hospitalized
There are currently two sets of criteria
1. The pneumonia severity index (PSI)
2. CURB-65
18. 18
CURB-65 – easy and commonly used scoring system
Confusion
Urea >7mmol/l
RR ≥30/min
BP <90/60 mmHg
Age >65 yrs
Score of 2 or more is associated with a 30-day mortality
of 9.2% and these patients should be admitted
19. Treatment
19
Initial therapy is usually empirical
Cover both typical and atypical organisms
Antibiotic treatment should be initiated as
expeditiously as possible
Supportive care
Adequate hydration
Oxygen therapy for hypoxia
Assisted ventilation when necessary
23. Failure to improve
23
Patients who are slow to respond should be
reevaluated at about day 3
Reasons
1. Other diagnoses- eg- tuberculosis
2. Complications
3. Resistant organisms=CA-MRSA
4. Inappropriate drug selection or route of
administration
25. Stages of parapneumonic
effusion
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Uncomplicated parapneumonic effusion
Less than half the hemithorax on decubitus films
Gram stain and culture negative
PH higher than 7.20
Treatment with antibiotics alone
Complicated parapneumonic effusion
Large free-flowing effusion, more than half the hemithorax
PH<7.20, LDH >1000U/L and glucose <40mg/dl
Gram stain or culture positive
Treatment with tube thoracostomy and antibiotics
Empyema
Loculated effusion or effusion with thickened pleura
Gross pus on aspiration
Treatment with tube thoracostomy
May require decortication
Radiographic images of the complications of pneumococcal pneumonia. (Left panel) Lung abscess with an air-fluid level in the right lung. Abscess cavity material is nearly always culture positive, and patients commonly defervesce within 48 hours of interventional drainage. (Right panel) Radiograph of necrotizing pneumonia in the left lung. This complication is usually culture negative; attempts at drainage or other surgical intervention for necrotizing pneumonia are strongly discouraged, as the outcome is poor
