Gram negative coccobacillus. H. aprophilus (now Aggregatibacter aphrophilus), H. ducreyi, H. haemolyticus (Can be confused with H. influenza in the COPD patient but is not a pathogen (PubMed), H. influenzae, H. parahaemolyticus, H. parainfluenzae, H. paraaprophilus, Haemophilus segnis (now Aggregatibacter segnis).
Being human, and, for Type b H. influenza, being an unvaccinated human.
H. influenza can be type b, other types (a,c,d,e, f as examples) and untypable.
Kids used to get type b, adults usually get other types or untypable. The vaccine has pretty much eradicated b disease.
H. influenza type a can also cause invasive disease (PubMed) .
Invasive disease should result in a work-up for antibody deficiencies and other immunodeficiencies (PubMed).
H. ducreyi: azithromycin 1 g orally in a single dose OR ceftriaxone 250 mg (IM) in a single dose OR ciprofloxacin 500 mg orally twice a day for 3 days OR erythromycin base 500 mg orally three times a day for 7 days (CDC).
H. aprophilus, parainfluenza and paraaprophilus endocarditis: ampicillin +/- gentamicin for four (native valve) to six weeks (prosthetic valve). A third generation cephalosporin OR aztreonam are reasonable alternatives if resistance OR allergies preclude the use of beta lactams.
Increasing resistance to tetracycline and sulfa precludes their use empirically.
Relevant links to my Medscape blog
Last update: 05/05/18