Infection of Pulmonary Parenchyma

Pneumonia

Infection of pulmonary parenchyma

Symptoms

·  Dyspnoea

·  Cough

·  Malaise

·  Anorexia

·  Fever

·  Sweats

·  Rigors

·  Pleuritic pain

·  Haemoptysis (less common)

·  Confusion (elderly esp)

·  Sputum - scant - green

- rusty (pneumococcal)

Signs

·  looks unwell + flushed

·  tachypnoea (early sign in elderly)

·  tachycardia

·  rigors and high temp (young)

·  herpes labialis (pneumococcal pneumonia)

·  reduced expansion on affected side

·  pleural rub

·  consolidation - dull percussion note

- increased vocal fremitus/ resonance

- bronchial breathing

or - localised inspiritory creps

Typical or Atypical?

CAUSES

Aspiration from Oropharyngeal Flora (most common)

·  S. pneumoniae

·  S. pyogenes

·  Mycoplasma pneumoniae

·  Haemophilus influenzae

·  Moraxella catarhalis

Airborne Infection

particles < 3 – 5 containing 1 or 2 micro organisms remain suspended in atmosphere unless removed by ventilation or filtration in the lungs.

Leads to contamination if they reach alveoli.

·  TB

·  Influenza

·  Legionellosis

·  Psittacosis

·  Histoplasmosis

·  Q fever

Blood-borne infection

·  Usually Staph aureus - from Right or Left sided bacterial endocarditis

- IV cannula infection

Classification

- guide to blind therapy, classify source

COMMUNITY ACQUIRED - strep. pneumoniae (commonest)

-  Mild: Mycoplasma pneumoniae and other 'atypical' bacteria - children and young adults.

-  Severe: H. influenzae, chlamydia pneumoniae, legionella pneumophilia

-  Viruses

NOSOCOMIAL (>48hrs after hospital admission)

- Gram-ve enterobacteria or staph aureus(10%)

- Pseudomonas (~50%), Klebsiella, Bacteroides, Clostridia

ASPIRATION (stroke, impaired conc, oesophageal disease)

- Anaerobes from oropharynx (Bacteriodes, Fusobacterium, Peptostreptococci)

IMMUNOCOMPROMISED

Bacterial

-  Strep pneumoniae

-  H. influenzae

-  Staph aureus

-  Moxarella catarrhalis

-  Mycoplasma

-  Gram -ve's

-  Actinomycetae

-  Legionella pneumophilia

Fungi

-  Candida spp (often preceded by oral candidiasis)

-  Aspergillus and Mucor spp.

-  Pneumocytis carinii – common in AIDS

Viruses

-  Cytomegalovirus – important in transplant patients

-  Herpes simplex virus

-  Varicella zoster virus

-  Measles virus

Primary or Secondary

- previously well or predisposing condition

·  COPD: Strep pneumoniae, H. influenzae, Moraxella catarrhalis

·  Post influenzae: Strep pneumoniae, H. influenzae, Staph aureus

SEVERITY

High Risk:

Clinical - Tachypnoea (resp rate > 30/min)

- Hypotension (diastolic < 60mmHg)

- Age > 60 yrs

- Underlying disease

- Confusion

- AF

- Multilobar involvement

Laboratory - low serum albumin (< 35g/L)

- high serum urea (>7mmol/L)

- Hypoxia (PaO2 < 8kPa)

- Leucopenia

- Leucocytosis

Treat Empirically / Admit - ITU (if severe)

Differential Diagnosis

- Fairly clear cut diagnosis

- Pulmonary infarction, pulmonary oedema, bronchial Ca and alveolitis ('velcro' creps) have similar presentation

- Acute pancreatitis and subphrenic abscess mimic lower lobe pneumonia

- Acute bronchitis causes fever and cough but no localising signs

INVESTIGATIONS

·  CXR

·  ABG’s/ pulse oximetry

·  U+E’s

·  FBC – WCC

·  Blod cultures

·  Sputum culture and microscopy (NB often contaminated by potentially pathogenic bacteria that have not actually caused infection)

·  Pleural fluid culture and microscopy

Serology for atypicals ( Legionella, Mycoplasma, Chlamydia, Coxiella)

·  Bronchoscopy - bronchial washings (use in severly ill or immunocompromised patients)

·  Percutaneous lung aspiration

·  Counter current immunoelectrophoresis (CIE) – blood, urine, sputum or CSF

-  identify pneumococcal antigen

Consider: ECG, cardiac enzyme-+

COMPLICATIONS:

·  Pleural effusion (may lead to Empyema)

·  Lung abscess

·  Septicaemia

·  Metastatic infections

·  Resp. failure

·  Jaundice

PREVENTION

Pneumococcal vaccine for patients with:

·  Chronic heart or lung conditions

·  Cirrhosis

·  Nephrosis

·  Diabetes Mellitus

·  Immunosuppression

MANAGEMENT

If severe – ITU

Antibiotics

Treat septicaemic shock

Monitor pulse, BP, temp, resp. rate 4 hourly

Pulse oximetry

Analgesia (NSAID) for pleuritic pain

IV fluids

O2 (aim for PaO2 > 8kPa)

Treatment

Community Acquired

1.  Uncomplicated

·  Broad spectrum penicllin

(amoxycillin, benzylpenicillin – if previously healthy chest)

(erythromycin -penicillin allergy)

+ Flucloxacillin – if Staph suspected

+ Erythromycin – if atypical suspected

2.  Severe, unknown aetiology

·  Erythromycin + 3rd Gen Cephalosporin (Cefuroxime or Cefotaxime)

+ Flucloxacillin – if Staph suspected

Hospital Acquired

·  Broad spectrum Cephalosporin (Cefotaxime or Ceftazidine)

Or

·  Antipseudomonal Penicillin + Aminoglycloside

+ Metronidazole – if anaerobic infection suspected

Treatment of Suspected Atypical