PNEUMONIA

ABOVE IS A NORMAL XRAY

MakambweM
PNEUMONIA
• This is an acute inflammation of the lung parenchyma distal to the terminal
bronchioles including respiratory bronchioles, alveolar ducts, alveolar spaces
and interstitial tissue.

• It can affect:
➢ The entire lobe: lobar pneumonia
➢ A segment of a lobe: Segmental/lobular pneumonia
➢ Alveoli contiguous (adjacent) to Bronchi-Bronchopneumonia
➢ Interstitial tissue- Interstitial pneumonia/atypical

• The differences between the above are made on X-ray.

• Pneumonia is usually caused by bacteria but can also be caused by viruses and
fungi.
• Clinically, it usually presents as an acute illness with cough, purulent sputum
(rusty color), breathlessness and fever together with physical signs or
radiological changes compatible with consolidation of the lung.
➢ A pulmonary consolidation is a region of lung tissue (normally
compressible) that has been filled with fluid instead of air. It occurs through
accumulation of inflammatory cellular exudate in the alveoli and adjoining
ducts.

➢ The liquid can be pulmonary edema,

inflammatory exudate, pus, inhaled water or
blood (from bronchial tree or hemorrhage from
a pulmonary artery)
➢ Consolidation must be present to diagnose pneumonia.
• In the elderly there is a subtler presentation of
symptoms.
• About 50% of pneumonia is pneumococcal. Figure 39: Chest X-ray showing lobar

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PREDISPOSING FACTORS FOR PNEUMONIA
• Preceding respiratory viral infections
• Alcoholism
• Cigarette smoking
• Underlying diseases such as heart failure, COPD
• Age extremes
• Immunosuppressive therapy and disorders
• Decreased consciousness, coma, seizure etc.
• Surgery and aspiration of secretions

CLASSIFICATION OF PNEUMONIA
• Pneumonia can be classified:
➢ 1. Morphologically/anatomical
➢ 2. Etiologically
➢ 3. Setting in which it is contracted
1. MORPHOLOGICAL/ ANATOMICAL CLASSIFICATION
• Pneumonia can be classified as:
➢ Lobar pneumonia: involving the entire lobe
➢ Segmental/lobular pneumonia: involving part of the lobe
➢ Bronchopneumonia: involving the alveoli contiguous (adjacent) to
Bronchi
➢ Interstitial pneumonia: involving the interstitial tissue.
ETIOLOGICAL CLASSIFICATION
• Cause of pneumonia can be
➢ Infectious
➢ Non-infectious

INFECTIOUS
• Bacterial:
➢ Streptococcus pneumoniae (50%)
➢ Haemophilus influenzae (7%)
➢ Klebsiella pneumoniae
➢ Pseudomonas aeruginosa
➢ Legionella pneumophilia (3%)
➢ Staphylococcus aureus (2%)
➢ Moraxella catarrhalis (2%)
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➢ Mycoplasma pneumoniae
➢ Chlamydophila pneumoniae
➢ Chlamydophila psittaci
➢ Coxiella burnetti (Q fever)

• Viral:
➢ Influenza viruses (A and B)
➢ Parainfluenza virus
➢ Cold viruses: adenovirus, corona virus, Astrovirus

• Fungal/Parasitic
➢ Pneumocystis Jirovercii pneumonia
➢ Aspergillosis

NON-INFECTIOUS
• This includes aspiration pneumonia
➢ Chemical insult such as in the aspiration of vomit
o Aspiration pneumonia is seen in patients at risk for aspiration (e.g.
alcoholics and comatose patients)
o Most often due to anaerobic bacteria in the oropharynx (e.g.
Bacteroides, Fusobacterium and Peptococcus) and other microbes such
as Enterobacteriacae, S. pneumoniae, S. aureus
o Classically results in a right lower lobe abscess: anatomically the right
main stem bronchus branches at a less acute angle than the left.
• Radiotherapy
• Allergic mechanisms

SETTING ACQUIRED
• Pneumonia is usually classified by the setting in which the person has
contracted
their infection:
➢ Community acquired pneumonia: with no underlying immunosuppression
or malignancy.
➢ Hospital acquired pneumonia
➢ Pneumonia in the immunocompromised (through genetic defect,
immunosuppressive medication or acquired immunodeficiency such as HIV)
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COMMUNITY ACQUIRED PNEUMONIA
• Occurs across all ages however is commoner at the extremes of age.
• Pneumonia can be classified either according to the organisms responsible for
the infection or by the site of disease.

• Classification according to etiology includes:

➢ Bacterial pneumonia: pneumococcus is the commonest cause overall.
Usually produce lobar or bronchopneumonia.
o Streptococcus pneumoniae (pneumococcal pneumonia)-50% of cases
o Haemophilus influenza-7% of cases
o Staphylococcus aureus-2% of cases
o Mycoplasma pneumoniae- 5-15% of cases
o Chlamydia pneumoniae-10% of cases
o Legionella pneumophila-3% of cases
o Oral anaerobic bacteria
o Mycobacterium tuberculosis
➢ Viral pneumonia: usually produce atypical pneumonia.
o Influenza A + B
o Respiratory syncytial virus
➢ Fungal pneumonia: Pneumocystis Jirovercii (causing pneumocystis
pneumonia-PCP) which is common in the immunosuppressed.
• Classification according to site of disease includes:
➢ Lobar pneumonia: consolidation affects one whole lobe
➢ Segmental/lobular: lobules of the lung are affected, and the infection is
centered on the bronchi and bronchioles.
➢ Bronchopneumonia: the alveoli adjacent to the bronchi are affected.
➢ Interstitial pneumonia (atypical pneumonia): inflammation within the
interstitium- there is an increase in lung markings on CXR.

LOBAR PNEUMONIA
• This is characterized by consolidation of an entire lobe of the lung.
• Usually bacterial, most common causes are Streptococcus pneumoniae (95%)
and Klebsiella pneumoniae.

• Classic gross phases of lobar pneumonia:

➢ Congestion- due to congested vessels and edema. This lasts less than 24
hours.
➢ Red hepatization- due to exudate, neutrophils, and hemorrhage filling the
alveolar air spaces, giving the normally spongy lung a solid consistency.
There is a firm, ‘meaty’ and airless appearance of the lung (it looks like a
liver).

➢ Gray hepatization- due to macrophage mediated degradation of red cells

and fibrin within the exudate. There is less hyperemia.

➢ Resolution- lysis and removal of the fibrin via sputum and lymphatics. It
begins after 8-9 days (without antibiotics) and there is sudden improvement
of the patient’s condition.
• This type of pneumonia usually develops in the distal airspaces adjacent to the
visceral pleura and then spreads to produce consolidation of all or part of the
lobe.

• On X-ray this appears as:

➢ Unifocal (but may be multifocal)
➢ Homogenous lung opacity limited by fissures with air bronchograms
(which become less obvious as the disease progresses).

➢ Round shaped pneumonia that may simulate a lung mass. (cavitations are
unlikely)
➢ A Parapneumonic effusion
➢ Note: lobar volume usually remains unchanged (but rarely it increases)

• Radiographic resolution is fairly rapid- 1 week; total resolution happens

within 2-6 weeks.
➢ Chest X-ray must be repeated 6 weeks after discharge unless complications
occur to rule out an underlying bronchial malignancy predisposing to
pneumonia by causing obstruction.
BRONCHOPNEUMONIA/LOBULAR
• Characterized by scattered patchy consolidation centered around bronchioles,
often multifocal and bilateral. With worsening disease, the opacities may
become
more homogenous.
• Pleural effusion or empyema, cavitation, pneumothorax and atelectasis are
common.
• Caused by a variety of bacterial organisms.

INTERSTITIAL PNEUMONIA (ATYPICAL PNEUMONIA)

• Characterized by diffuse interstitial infiltrates.
• Presents with relatively mild upper respiratory symptoms (minimal sputum
and
low fever), ‘atypical presentation’.
• Most often caused by bacteria or viruses. SHOWN BELOW

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TYPES OF PNEUMONIA
CAUSES OF LOBAR
PNEUMONIA
ORGANISM COMMENTS
Streptococcus • Most common cause of community acquired pneumonia.
pneumoniae • Seen in middle-adults and elderly.
• Affects malnourished and debilitated individuals,
especially elderly in
nursing homes, alcoholics and diabetics (enteric flora that
Klebsiella
is aspirated)
pneumoniae
• Thick mucoid capsule results in gelatinous sputum
(current jelly)
• Often complicated by abscess.
CAUSES OF
BRONCHOPNEUMONIA
ORGANISM COMMENTS
• Most common cause of secondary pneumonia (bacterial
Staphylococcus pneumonia
aureus superimposed on a viral upper respiratory tract infection)
• Often complicated by abscess or empyema
• Common cause of secondary pneumonia and pneumonia
Haemophilus
superimposed on
influenza
COPD (leads to exacerbation of COPD)

Pseudomonas
• Pneumonia in cystic fibrosis patients
aeruginosa
• Community-acquired and pneumonia superimposed on
Moraxella
COPD (leads to
catarrhalis
exacerbation of COPD)
• Community-acquired pneumonia
• Pneumonia superimposed on COPD or pneumonia in
Legionella immunocompromised states.
pneumophila • Transmitted from water source.
• Intracellular organism that is best visualized by silver
stain.
CAUSES OF
INTERSTITIAL
(ATYPICAL)
PNEUMONIA
ORGANISM COMMENTS
• Most common cause of atypical pneumonia, usually
affects young adults.
• Complicates include autoimmune hemolytic anemia (IgM
Mycoplasma
against antigen
pneumoniae
on RBCs causes cold hemolytic anemia) and erythema
multiforme.
• Not visible on gram stain due to lack of cell wall
Chlamydia • Second most common cause of atypical pneumonia in
pneumoniae young adults
Respiratory
• Most common cause of atypical pneumonia in infants.
syncytial virus
• Atypical pneumonia with post-transplant
Cytomegalovirus
immunosuppressive therapy

• Atypical pneumonia in elderly, immunocompromised and

those with
preexisting lung disease.
Influenza virus
• Also increases risk for superimposed S aureus or H influenza
bacterial
pneumonia
• Atypical pneumonia with high fever (Q fever).
• Coxiella is a Rickettsial organism that causes pneumonia and
Coxiella burnetti does not
require arthropod vector for transmission and does not produce
skin
rash.
RISK FACTORS FOR COMMUNITY
ACQUIRED PNEUMONIA
AGE <16 or >65 years
HIV infection, diabetes mellitus,
CO-MORBIDITIES chronic kidney disease, malnutrition,
recent viral respiratory infection

Cystic fibrosis, bronchiectasis,

OTHER RESPIRATORY COPD, obstructing lesion
CONDITIONS (endoluminal cancer, inhaled foreign
body)
Cigarette smoking, excess alcohol,
LIFESTYLE
intravenous drug use
Immunosuppressant therapy
IATROGENIC
(including prolonged corticosteroids)

CLINICAL FEATURES
• Clinical features vary according to the immune state of the patient and the
infecting agent.
• Symptoms:
➢ Fever and chills: this can be as high as 39.5- 40.5oC. If swinging fevers are
present, this often indicates empyema.
➢ Cough: may be dry or productive and hemoptysis can occur.
o In pneumococcal pneumonia, sputum is characteristically rust-colored or
yellow-green (indicating pus).
➢ Chest pain: pleuritic in nature due to inflammation of pleura (mediated by
bradykinin and prostaglandin E2).
o The pleuritic chest pain is worsened during inspiration and coughing
➢ Breathlessness: alveoli become filled with pus and debris, impairing gas
exchange.
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➢ In the elderly community acquire pneumonia (CAP) can present with
confusion or nonspecific symptoms such as recurrent falls. CAP should
always be considered in the differential diagnosis of sick elderly patients
given their frequently atypical presentation.
➢ Where symptoms have been present for several weeks or have failed to
respond to standard antibiotics, the possibility of Tuberculosis should always
be remembered.
• Signs:
➢ Tachypnea and increased pulse rate
➢ Cyanosis may be present
➢ There will be dullness to percussion
➢ Bronchial breathing (Increased breath sounds): may be heard over areas of
consolidated lung.
➢ Coarse crepitations are often heard on auscultation, due to consolidation of
the lung parenchyma.
➢ A pleural rub may be heard early on in the illness
➢ Elevated WBC count.
➢ Extrapulmonary manifestation: may be indicative of causative agent.
Pneumonia Manifestations
• Myalgia, arthralgia and malaise
• Headache
• Meningoencephalitis and other neurological
Legionella
abnormalities (less
pneumonia
common)
• Abdominal pain, diarrhea and vomiting (common)
• Hepatitis
• Myalgia, arthralgia and malaise
• Myocarditis and pericarditis
Mycoplasma
• Erythema multiforme and erythema nodosum
pneumonia
• Stevens-Johnson syndrome (Rare complication of
pneumonia)
Pneumococcal
• Labial herpes simplex reactivation
pneumonia

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• The type and extent of depends on the severity of the illness, which also
guides
where the patient should be managed and predicts their outcome.
• Severity is commonly assessed by CURB-65 or CRB=65 score. The CRB=65
score is used in the community where the serum urea level is not usually
available. 1 point for each
➢ C- confusion present (abbreviated mental test score <8/10)
➢ U- urea levels >7 mmol/L
➢ R- respiratory rate >30/min
➢ B- systolic BP <90 or diastolic BP <60
➢ 65- age>65
• Score 0-1: treat as outpatient
• Score 2: Admit to hospital
• Score 3+: Often require ICU care. Mortality rates increase with
increasing
score.
• Other severity scores are also used e.g. Pneumonia Severity index (PSI)
INVESTIGATIONS
• The clinical presentation varies between different causative organisms but
there is considerable overlap.

• Streptococcus pneumoniae is the commonest single cause and all treatment

and investigation strategies need to cover this. The most likely causative
pathogens must be treated while considering alternative less common infectious
causes(such as tuberculosis) or an alternative pathology (e.g. lung cancer).

• All patients admitted to hospital should have a chest X-ray, blood tests and
microbiological tests.

➢ Chest X-ray: must be repeated 6 weeks after discharge unless complications

occur to rule out an underlying bronchial malignancy predisposing to
pneumonia by causing obstruction
o Strep. Pneumoniae: consolidation with air bronchograms, effusions and
collapse due to retention of secretions can all be seen. Radiological
abnormalities can lag behind clinical signs. A normal CXR on
presentation should be repeated after 2-3 days where community
acquired pneumonia is suspected.
o Mycoplasma: Usually one lobe is involved but infection can be bilateral
and extensive

o Legionella: There is lobar and then multi-lobar shadowing with the

occasional small pleural effusion. Cavitation is rare.
➢ Sputum gram stain and culture: required for all patients
o S. pneumoniae: gram positive diplococci

o S. aureus: gram positive organisms commonly in clusters like a bunch of

grapes or in rods.
o Blood culture should be done for all patients who have moderate to
severe community acquired pneumonia, ideally before antibiotics are
administered. In S. pneumoniae infection, positive blood culture
indicates more severe disease with greater mortality.
➢ Blood tests: Full blood count, urea & electrolytes, biochemistry, C-reactive
protein, HIV testing
o Strep pneumoniae: WBC> 15 x109/L (90% polymorphonuclear
leukocytosis), ESR> 100mm/hour, CRP> 100mg/L.

o Mycoplasma: WBC is usually normal. In the presence of anemia,

hemolysis should be ruled out (direct Coomb’s test and measurement of
cold agglutinins).

o Legionella: there is Lymphopenia without marked leukocytosis,

hyponatremia, hypoalbuminemia and high serum levels of liver
aminotransferases.
➢ Pulse oximetry and arterial blood gas analysis is necessary if oxygen
saturation is below 94%.

MANAGEMENT OF PNEUMONIA
• Antibiotics
➢ Administer first dose within 4 hours of presentation in hospital and
treatment
should not be delayed while investigations are awaited.
➢ The antibiotic regimen should be adjusted specifically once culture and
sensitivity results are available.
EMPERICAL TREATMENT
• Benzyl penicillin 1-2 MU IV QID for 5 days (as soon as the symptoms and
respiratory
rates are controlled change to oral medication i.e. Amoxicillin 500mg for
remaining
days) or
• Ceftriaxone 1-2g daily for 7 days. If allergic to penicillin use
• Erythromycin 500mg PO QID for 7 days

2. SUPPORTIVE THERAPY
• Oxygen: supplemental oxygen should be administered to maintain
saturations between 94% and 98% provided the patient is not at risk of
carbon dioxide retention due to loss of hypoxic drive in COPD.
In patients with known COPD, oxygen saturations should be maintained
between 88% and 92%, normally with controlled oxygen via fixed
percentage delivery mask.
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➢ Ensure adequate oxygenation to patients with cyanosis, significant
hypoxemia, severe dyspnea, circulatory disturbance or delirium.
• Intravenous fluids: required in hypotensive patients showing evidence
of volume
depletion.
• Thromboprophylaxis if admitted for more than 12 hours subcutaneous
low
molecular weight heparin should be prescribed unless contraindications
exist.
• Physiotherapy: chest physiotherapy is not needed unless sputum
retention is an issue.
• Nutritional supplementation
• Antipyretics should be given.
• Analgesia: paracetamol or NSAIDs help treat pleuritic pain, thereby
reducing the risk of further complications due to restricted breathing
because of pain e.g.
sputum retention, atelectasis or secondary infection.
➢ Paracetamol 500mg to 1g PO TDS/QID

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