Bacteremia associated with Haemophilus influenzae type e biotype 4

Area of Science:

• Microbiology
• Infectious Diseases
• Clinical Bacteriology

Background:

• Haemophilus influenzae is a significant human pathogen, with non-typeable strains commonly causing respiratory and ear infections.
• Encapsulated strains, such as type b (Hib), were historically associated with severe invasive diseases, but vaccination has reduced their incidence.
• Other encapsulated serotypes (a, c, d, e, f) are less common but can cause invasive disease, particularly in specific populations.

Observation:

• A single antemortem blood culture from a 60-year-old male patient yielded positive results.
• The patient presented with a diagnosis of abdominal carcinomatosis, indicating advanced cancer.
• The isolated bacterium was identified as Haemophilus influenzae type e biotype 4.

Findings:

• Haemophilus influenzae type e biotype 4 was successfully isolated from the patient's bloodstream.
• This represents a rare isolation of this specific serotype and biotype in a clinical setting.
• The isolation occurred in the context of a patient with significant underlying malignancy.

Implications:

• This case suggests that Haemophilus influenzae type e biotype 4, though uncommon, can cause bloodstream infections.
• Patients with advanced cancer and potential immune compromise may be at risk for infections with less common H. influenzae serotypes.
• Further surveillance and case reporting are warranted to understand the clinical significance and epidemiology of non-b encapsulated H. influenzae types.