2.
Definition
Classification
Lobar pneumonia and Bronchopneumonia
Community acquired pneumonia
Hospital acquired pneumonia
Pneumonia in immunocompromised patient
Suppurative and aspiration pneumonia
Index
3.
Pneumonia is defined as an acute respiratory illness
associated with recently developed segmental, lobar or
multilobar radiological shadowing.
Definition
4.
It is classified as
1. Community-acquired pneumonia (CAP)
2. Hospital acquired (nosocomial) pneumonia (HAP)
3. Pneumonia occurring in immunocompromised hosts.
Classification
5.
Lobar pneumonia and
Bronchopneumonia
Lobar pneumonia is a
radiological and
pathological term referring
to homogeneous
consolidation of one or
more lung lobes, often with
pleural inflammation.
Bronchopneumonia refers
to patchy alveolar
consolidation with
bronchial and bronchiolar
inflammation, often
affecting both lower lobes.
6.
20% of childhood deaths worldwide are due to pneumonia.
Most patients may be safely managed at home but hospital
admission is necessary in 20–40%.
In hospital, death rates are typically 5–10%, rising to 50% in
severe illness.
The most common organism is Streptococcus pneumoniae,
Haemophilus influenzae should be considered in elderly
patients, while Mycoplasma and Chlamydia pneumoniae are
more often seen in the young.
Rarer causes of severe pneumonia include Legionella ,
Chlamydia Psittaci , Staph. aureus , Burkholderia pseudomallei
Community-acquired pneumonia
7.
Fever, rigors, shivering and vomiting.
Pleuritic chest pain is common and may be the presenting
feature.
Cough is followed by mucopurulent sputum
(rust-coloured sputum - Strep. pneumoniae infection).
Patients have poor appetite and headache.
Haemoptysis (occasionally).
Examination may reveal crepitations or bronchial
breathing, suggesting underlying consolidation.
Clinical features
8.
Chest X Ray: In lobar pneumonia, a homogeneous opacity
localised to the affected lobe or segment is seen.
It may also identify complications such as a
parapneumonic effusion, intrapulmonary abscess
formation, or empyema.
Investigations
10.
Sputum is sent for microscopy (Gram and Ziehl–Neelsen
stains), culture and sensitivity testing.
Blood culture is frequently positive in pneumococcal
pneumonia.
Acute and convalescent samples for Mycoplasma, Chlamydia,
Legionella and viral serology should be sent.
Legionella antigen can be detected in urine and pneumococcal
antigen can be detected in blood or sputum.
Throat/nasopharyngeal swabs may be helpful during an
influenza epidemic.
Many cases of CAP are managed successfully without
identification of the organism.
Microbiological investigations
11.
Arterial Blood gas should be done if SaO2 is < 93% or if
clinical features suggest severe pneumonia.
WBC count is often marginally raised or even normal in
patients with pneumonia caused by atypical organisms.
A very high (> 20 × 109/L) or low (< 4 × 109/L) WCC may
be seen in severe pneumonia.
U&Es and LFTs should be checked.
C reactive protein is typically elevated.
Blood investigations
12.
A scoring system to assess disease severity helps to
guide antibiotic and admission policies.
- CURB 65 Score
Management
13.
CURB SCORE
Defined as an abbreviated mental test score ≤ 8, or new disorientation
in person, place or time. (A urea of 7 mmol/L ≅ 20 mg/dL.)
15.
High concentrations (> 35%) of oxygen (preferably
humidified) should be administered to all patients with
tachypnoea, hypoxaemia, hypotension or acidosis, aiming to
keep PaO2 ≥ 8 kPa (60 mmHg) or SaO2 ≥ 92% .
IV fluids are given in severe disease, and in elderly or vomiting
patients.
If possible, take blood cultures prior to starting antibiotics but
do not delay treatment in severe pneumonia.
Consider analgesia for pleural pain, and physiotherapy if cough
issuppressed, e.g. due to pain.
16.
Refer to ICU for consideration of continuous positive
airways pressure (CPAP) or intubation if there is:
1. a CURB score of 4–5 and the patient is failing to respond
to treatment;
2. persistent hypoxia despite high inspired O2;
3. progressive hypercapnia;
4. severe acidosis;
5. shock;
6. depressed conscious level
18.
Review should be arranged at ~6 weeks
Chest X ray to be taken if there are persistent symptoms,
physical signs or reasons to suspect underlying
malignancy.
Influenza vaccination and pneumococcal vaccination are
recommended for selected high-risk patients.
Follow-up and prevention
19.
Hospital-acquired pneumonia (HAP) is defined as a new
episode of pneumonia occurring at least 2 days after
admission to hospital.
The most important distinction between HAP and CAP
lies in the spectrum of organisms, with the majority of
hospital-acquired infections caused by Gram-negative
bacteria, including Escherichia, Pseudomonas and
Klebsiella spp. Staph. aureus/MRSA are also common.
The clinical features and investigation of patients with
HAP are very similar to those of CAP.
Hospital-acquired pneumonia
20. Patients who have received no previous antibiotics can be treated
with co-amoxiclav or cefuroxime.
If the individual has received a course of recent antibiotics, then
piperacillin/tazobactam or a thirdgeneration cephalosporin should
be considered.
Antipseudomonal cover may be provided by meropenem or a
third-generation cephalosporin combined with anaminoglycoside.
MRSA cover may be provided using vancomycin or linezolid.
It is usual to start with broad-based cover, discontinuing less
appropriate antibiotics as culture results become available.
Physiotherapy is important to aid expectoration in the immobile
and elderly, and nutritional support is often required.
The mortality from HAP is high (~30%).
Management and Prognosis
21.
In suppurative pneumonia there is destruction of the lung
parenchyma by the inflammatory process.
Microabscess formation is a characteristic histological feature of
suppurative pneumonia; the term ‘pulmonary abscess’ refers to
large localised collections of pus.
Organisms include Staph. aureus and Klebsiella pneumoniae.
Suppurative pneumonia may be produced by primary infection,
inhalation of septic material from the oropharynx or
haematogenous spread
Bacterial infection of a pulmonary infarct or of a collapsed lobe
may also produce suppurative pneumonia or lung abscess.
Suppurative and aspiration
pneumonia
22.
Chest X Ray characteristically demonstrates a dense
opacity with cavitation and/or a fluid level.
Treatment with co-amoxiclav may be effective.
If anaerobes are suspected, oral metronidazole should be
added.
Prolonged treatment for 4–6 wks may be required.
23.
Pulmonary infection is common in patients receiving
immunosuppressive drugs and in diseases causing defects of
cellular or humoral immune mechanisms.
Most infections are caused by the same common pathogens
that cause CAP.
Gram-negative bacteria, especially Ps. aeruginosa, are more of
a problem than Gram-positive organisms, however, and unusual
organisms or those normally considered to be non-pathogenic
may become ‘opportunistic’ pathogens.
More than one organism may be present.
Pneumonia in the
immunocompromised patient
24.
Patients may have non-specific symptoms and the onset tends to
be less rapid in those with opportunistic organisms such as
Pneumocystis jirovecii and mycobacterial infections.
In P. jirovecii pneumonia, cough and breathlessness can precede
the appearance of CXR abnormality by several days.
At presentation the patient is usually pyrexial and hypoxic with
normal breath sounds.
Induced sputum or bronchoscopy with bronchoalveolar lavage
or bronchial brushings may help to establish a diagnosis.
Clinical features and investigations
25.
Whenever possible, treatment should be directed against
identified organism.
Frequently, the cause is not known and broadspectrum
antibiotic therapy is required (e.g. a third-generation
cephalosporin, or a quinolone, + an antistaphylococcal
antibiotic, or an antipseudomonal penicillin + an
aminoglycoside)
Treatment is thereafter tailored according to the results of
investigations and the clinical response.
Management
