Written as an editorial commentary regarding Brooks et al. Haemophilus Species, a Rare Cause of Vertebral Osteomyelitis: Case Report and Review of the Literature pages 191–195 of the Journal.
The report of a patient with Haemophilus parainfluenzae vertebral osteomyelitis by Brooks et al1 in this issue of infectious diseases in clinical practice reminds us that invasive Haemophilus infection is now primarily an adult disease and that Haemophilus species other than Haemophilus influenzae type b (Hib) are significant pathogens in the postconjugated-Hib-vaccine era. In the preconjugated-Hib-vaccine era, our pediatric hospitals were replete with infants and children with invasive Hib meningitis, pneumonia, epiglottitis, septic arthritis, orbital cellulitis, and primary bacteremia.2 Now that an estimated 95% of US children are Hib-vaccinated, invasive Hib disease is a rarity in the pediatric population.3 The most common source of Haemophilus bacteremia in adults is pneumonia and the second most common species of Haemophilus-causing bacteremia is H. parainfluenzae.4 Infective endocarditis (the “H” in classic Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, Kingella species group endocarditis) is another well-known source of Haemophilus bacteremia and H. parainfluenzae is the most common cause of Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, Kingella species endocarditis.5,6 Although bacteremia only infrequently accompanies invasive vertebral Haemophilus disease (2 of 15 patients), it is likely that the 13 nonbacteremic patients reported by Brooks et al1 had prior transient bacteremia with disc-space seeding.1Haemophilus species commonly colonize the upper respiratory tract of patients without pulmonary disease and the lower respiratory tract of patients with chronic obstructive pulmonary disease and cystic fibrosis.7 Pneumonia likely results from aspiration of Haemophilus species colonizing the upper respiratory tract in normal patients and invasion of Haemophilus species colonizing the lower respiratory tract in patients with chronic obstructive pulmonary disease or cystic fibrosis. Translocation of colonizing Haemophilus species is likely the source of the 41 episodes of primary (spontaneous) bacteremia in 287 patients with Haemophilus bacteremia in the literature review by Desmett et al in 2014.4
Another important lesson provided by the patient of Brooks et al1 is one that is often lost in the rush and shuffle to care for acutely ill patients with progressive spinal and paraspinal infections: the avoidance of antimicrobial therapy until an appropriate specimen, in this case a bone biopsy, is obtained for culture and pathologic examination. Infectious disease specialists are often faced with prescribing 6 to 8 weeks of parenteral antimicrobial therapy for patients with spinal infection who have sterile biopsy cultures because of prior antibiotic administration. This may result in the need to use broad-spectrum/more toxic agents rather than narrow-spectrum/less toxic therapy than might have been possible had biopsy cultures been available to direct therapy.
In summary, (1) Haemophilus species must be added to the pathogens considered in the differential diagnosis of adult spondylodiscitis/vertebral osteomyelitis. (2) Bacteremia does not usually accompany Haemophilus vertebral osteomyelitis. (3) Surgical intervention is infrequently required for cure (4 of 15 patients). (4) In the absence of bacteremia, when spondylodiscitis/vertebral osteomyelitis is suspected, antimicrobial therapy should be withheld until diagnostic aspiration/biopsy for culture is performed. (5) Haemophilus species are now primarily adult pathogens and familiarity with their diverse clinical manifestations including spinal and perispinal infection should be part of every internist's education and differential diagnosis.1
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type B disease at the beginning of the 21st century: global analysis of the disease burden 25 years after the use of the polysaccharide vaccine and a decade after the advent of conjugates. Clin Microbiol Rev
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type B. In: Epidemiology and Prevention of Vaccine-Preventable Diseases
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. 9th ed. Philadelpia, PA: Elsevier; 2020:2743–2752.