Community-acquired Pneumonia

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Community-acquired Pneumonia

• Medical Journal of Australia 2002 176 341-347
• Presented by Ri ??? Oct 28, 2002

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Introduction

• Possible pathogens
• Antibiotics choosing
• Antibiotics resistance
• Be treated at home or hospital?

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Epidemiology

• In US, mortality averages 14 in 2000.
• Less than 1 for those outpatients

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Risk Factors
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Causative Organisms

• Most common S. pneumoniae
• H. influenzae
• S. aureus
• Enteric gram-negative bacteria
• Mycoplasma pneumoniae
• Chlamydia
• Legionella
• Mycobacterium tuberculosis
• Others (Pseudomonas, virus)

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Aspiration Pneumonia

• An variant of CAP
• Elderly people, bulbar weakness, laryngectomy or
  stroke
• S. aureus, H. influenzae, and G (-) aerobes
• No anaerobes? Chest 1999 115 178-183.

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Diagnosis

• Two or more
• Fever
• Rigors
• New-onset cough
• Change in sputum color if chronic cough
• Chest discomfort
• Dyspnea

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Investigation

• CXR
• Clearly show consolidation
• Poor guide to the likely pathogen
• D/D from other cause
• Initially appears normal?
• Sputum smear culture
• Try to identify pathogens

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Investigation

• CBC, BCS and ABG
• Blood culture
• Most specific diagnostic test
• Others
• Legionella urinary antigen test
• Viral immunofluorescence testing
• Serological diagnosis
• PCR

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Management

• What is the severity?
• Where should the patient be managed?
• Which antibiotics should be used?

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Risk stratification
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Pneumonia Severity Index
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Mortality
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Antibiotics Choice

• Resistance
• Streptococcus
• H. influenzae
• Mycoplasma, Chlamydia and Legionella

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Incidence of Drug-resistant Pneumococcus (DRSP)
in CAP

• Cefotaxime 42
• Meropenem 52
• Erythromycin 61
• Trimethoprim/sulfamethoxizole 92
• Quinolone (ciprofloxacin) 2.9
• Whitney CG, Increasing prevalence of
  multi-drug resistant Streptococcus pneumonia in
  the United States N Engl J Med 2000
  3431917-1924

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Low-risk patients

• Risk class?and many patients in classes?and ?
  (PSI lt 90)
• Oral antibiotics in the community
• Amoxicillin roxithromycin or doxycycline
• Allergy or resistance?
• Oral cefuroxime or iv Rocephin with roxithromycin
  or doxycycline po

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Higher-risk patients

• PSI risk class?
• Require IV therapy
• Benzylpenicillin IV roxithromycin or
  doxycycline po
• S. aureus and G (-) rods
• flucloxacillin or dicloxacillin
• aminoglycoside or extended-spectrum
  cephalosporin

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Highest-risk patients

• PSI risk class?
• Early broad-spectrum parenteral therapy
• IV erythromycin Rocephin or Claforan
• IV erythromycin penicillin gentamicin

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Role of Fluoroquinolone

• Reserved for
• Treatment failure
• Allergy to other agents
• DRSP
• Avoid widespread using

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Supportive Care

• Hypoxaemia - continuous O2 therapy
• Asthma or COPD bronchodilator
• Adequate hydration, but avoid overload
• ARF temporary dialysis
• Pain control

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Follow-up

• Improvement on CXR is often slow
• Most patients recovery in 24 to 72 hrs
• Failure to improve ? review of the case
• Abx failure is not usually the reason

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Treatment Failure

• Is the diagnosis correct?
• Is the patient taking the Abx?
• Need admission IV therapy?
• Any complication?
• Any obstruction?
• Abx resistance?
• TB? HIV?
• Advanced investigation

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Prevention and Public Health

• Risk factors age gt 65
• Influenza vaccination annually
• Pneumococcal vaccination five-yearly
• Legionnaires disease, TB and psittacosis
  notifiable disease

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Conclusion

• CAP is caused by a range of organisms, most
  commonly S. pneumoniae
• CXR is required for diagnosis
• A risk score can aid Tx decisions
• Antibiotics should be given according to specific
  pathogen

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• Thanks for Your Attention !