Haemophilus influenzae

Introduction

Gram negative bacilli. Requires coagulation factors V & X. ALA -; hemolysis -. Encapsulated & unencapsulated strains.

Epidemiology

• unencapsulated strains present in sputum of 30-60% of normal adults & 60-80% of patients with COPD

Pathology

• bacteremia is almost always associated with encapsulated strains
• both encapsulated & unencapsulated strains cause:
  • pulmonary infections
  • otitis
  • sinusitis
  • epiglottitis
  • pneumonia

Laboratory

• Haemophilus influenzae serology
• Haemophilus influenzae serotype
• Haemophilus influenzae antigen
• Haemophilus influenzae identified in isolate
• Haemophilus influenzae DNA
  • Haemophilus influenzae acs gene
  • Haemophilus influenzae bcs gene
  • Haemophilus influenzae ccs gene
  • Haemophilus influenzae dcs gene
  • Haemophilus influenzae ecs gene
  • Haemophilus influenzae bex gene
  • Haemophilus influenzae hpd gene
  • Haemophilus influenzae lex2 gene
• Haemophilus influenzae rRNA
• Haemophilus influenzae identified by culture
• see ARUP consult

Complications

Pneumonia:

• most cases associated with COPD or alcoholism
• also occurs in military recruits
• copious sputum production
• lower lobes affected more frequently than upper lobes
• chest X-ray findings are consistent with bronchopneumonia or lobar pneumonia
• pleural effusion occurs in 30% of patients
• cavitation is rare

Management

• outpatient
  • oral cephalosporin, 2nd or 3rd generation
  • Augmentin
  • alternative agents
    • doxycycline
    • clarithromycin
    • azithromycin
    • fluoroquinolone
• hospitalized patient
  • ceftriaxone
  • cefotaxime
  • ampicillin 1-2 g IV q 6 hours if isolate is susceptible.

More general terms

• Haemophilus

Additional terms

• haemophilus b vaccine; HIB vaccine (HibTITER, Hiberix)