Bordetella holmesii infection: current knowledge and a vision for future research

Abstract

Bordetella holmesii is a recently recognized Gram-negative bacterium causing both pertussis-like respiratory symptoms and invasive infections, such as bacteremia, pneumonia, meningitis, arthritis, pericarditis and endocarditis. Few data are available on its epidemiological characteristics, mostly related to respiratory infections. However, these are frequently misdiagnosed as a Bordetella pertussis infection as most diagnostic tests routinely used are not species-specific, thus biasing the epidemiological studies of both strains, as well as the efficacy studies on pertussis vaccination. There is no accepted agreement on treatment and it remains unknown if antimicrobial prophylaxis is indicated in certain clinical settings. We review here the current knowledge on B. holmesii and the need for further research.

Keywords:

• 16S ribosomal RNA sequencing
• arthritis
• bacteremia
• bhoE
• Bordetella holmesii
• Bordetella pertussis
• Bordetella-specific polymerase chain reaction
• cellulitis
• endocarditis
• epidemiology
• insertion sequences IS481
• hIS1001
• matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
• meningitis
• pericarditis
• pertussis-like illness
• pneumonia
• recA
• vaccination

Acknowledgements

The authors thank Stéphane Emonet, Patrick Linder, Karl Perron and François Barja for the figure, Martine Leplay Fontana for her help in retrieving articles and Rosemary Sudan for editing assistance.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Key issues

• Bordetella holmesii is a recently identified Gram-negative bacterial species that can cause respiratory pertussis-like illness, but also invasive infections, unlike Bordetella pertussis that mainly affects the respiratory system.

• A variety of invasive infections due to B. holmesii has been described, that is, bacteremia, endocarditis, pericarditis, pneumonia, bronchitis, meningitis, arthritis, discitis and cellulitis.

• B. holmesii is genetically close to the avian Bordetella species; lateral transfer of genetic material may have enabled B. holmesii strains to infect humans by acquisition of pathogenic factor(s) and may enhance its pathogenicity in the future.

• Only limited data are available on B. holmesii epidemiology, but its prevalence appears to differ worldwide; further studies are needed and should be performed in regions with a high circulation of B. holmesii.

• The bacterial culture of B. holmesii is cumbersome and its growth is inhibited by cephalexin, which is widely used in Bordetella culture media.

• B. holmesii respiratory infection is often misdiagnosed as a B. pertussis infection since most laboratories cannot discriminate between both species

• The susceptibility of B. holmesii to antibiotics differs from that of B. pertussis; in particular, macrolides may not be the first choice treatment.

• Misdiagnosing B. holmesii as B. pertussis respiratory infection could potentially bias pertussis vaccine efficacy studies.