What the pediatrician should know about non-typeable Haemophilus influenzae.
Non-typeable Haemophilus influenzae (NTHi) live exclusively in the pharynges of humans and are increasingly recognized as pathogens that cause both localized infections of the respiratory tract (middle ear spaces, sinuses, and bronchi) and systemic infections such as bacteraemia and pneumonia. Only one vaccine antigen of NTHi, Protein D, has been extensively studied in humans and its efficacy in preventing NTHi otitis media is modest. Recent genetic analyses reveal that NTHi are closely related to Haemophilus haemolyticus (Hh), previously thought to be a non-pathogenic commensal of the pharynx. This review discusses the differences between the pathogenic potential of encapsulated and non-typeable Hi. In addition, information on the lifestyles and bacterial characteristics of NTHi and Hh as they pertain to their pathogenic capacities and the value of the Haemophilus taxonomy to clinicians are presented. Further, the epidemiology and mechanisms of NTHi antibiotic resistance, which include production of β-lactamase and alterations of penicillin-binding protein 3, are reviewed, as are the challenges of vaccine antigen discovery in NTHi.
D5101 Medical Professional Building SPC 5718, Ann Arbor, MI 48109-5718, United States. Electronic address: gilsdorf@umich.edu.
Janet R
JR
Gilsdorf
D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000145:classification / Q000187:drug effects / Q000235:genetics; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D010372:Pediatrics
D000900:Anti-Bacterial Agents; D018073:Haemophilus Vaccines
Antibiotic resistance; Bacterial capsule; Beta lactamase negative ampicillin resistance; Haemophilus haemolyticus; Haemophilus influenzae; NTHi vaccines; Non typeable Haemophilus influenzae; Taxonomy