Microbiology

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).

Epidemiologic Risks

Being human, and, for Type b H. influenza, being an unvaccinated human.

Syndromes

H. influenzae: otitis media, sinusitis, epiglottitis, pneumonia, meningitis (esp children who are not vaccinated).

H. ducreyi: chancroid painful, ulcerated, genital ulcers with inguinal adenopathy.

H. aprophilus (now Aggregatibacter aphrophilus), parainfluenza and paraaprophilus: endocarditis. Part of any disease where spit is an issue.

Treatment

H. influenzae: any and all beta lactams (except ampicillin) and quinolones. See specific disease. Type b with increasing resistance to ampicillin.

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.

Notes

Increasing resistance to tetracycline and sulfa precludes their use empirically.

ICD9 Codes (Soon to be supplanted by ICD10)

Hemophilus influenzae NEC 041.5; arachnoiditis 320.0; bronchopneumonia 482.2; cerebrospinal inflammation 320.0; infection NEC 041.5; leptomeningitis 320.0; meningitis 320.0; meningomyelitis 320.0; pneumonia (broncho-) 482.2.