Clinical Laboratory Perspective on Streptococcus halichoeri, an Unusual Nonhemolytic, Lancefield Group B Streptococcus Causing Human Infections

• Published in: Emerging infectious diseases 2021-05, Vol.27 (5), p.1309-1316
• Main Authors: Shakir, Salika M, Gill, Rahul, Salberg, Jonathan, Slechta, E Susan, Feldman, Mark, Fritsche, Thomas, Clarridge, Jill, Sharp, Susan E, Fisher, Mark A
• Format: Article
• Language: English
• Subjects: Acids; Antimicrobial agents; antimicrobial resistance; Back pain; bacteria; Biopsy; Case studies; Causes of; Clinical Laboratory on Human Infections Caused by Unusual Nonhemolytic Lancefield Group B; Diabetes; Edema; grey seals; Hypertension; Identification and classification; Infectious bone diseases; Ionization; Joint diseases; Joint replacement surgery; Joint surgery; Laboratories; Magnetic resonance imaging; Mass spectrometry; Original Research; Penicillin; Prostheses; Scientific imaging; Streptococcal infections; streptococci; Streptococcus; Streptococcus halichoeri; Streptococcus infections; underlying health conditions; Vertebrae
• ISSN: 1080-6040; 1080-6059
• DOI: 10.3201/eid2705.203428

Streptococcus halichoeri is a relatively newly identified species of pyogenic streptococci that causes zoonotic infection in humans. S. halichoeri was first described in 2004 as indigenous to seals, and only 8 reports of human S. halichoeri infection have been published. S. halichoeri grows as small, white, nonhemolytic colonies and may be strongly catalase-positive on routine blood agar media, which can lead to isolates being misidentified as coagulase-negative staphylococci. S. halichoeri tests positive for Lancefield group B antigen, like S. agalactiae, but can be identified with matrix-assisted laser desorption/ionization time of flight mass spectrometry or partial 16S rRNA sequencing. We describe 3 cases of S. halichoeri bone and joint infections in patients in the United States with underlying health conditions. In addition, we examine the microbiologic characteristics of S. halichoeri and discuss the importance of fully identifying this organism that might otherwise be disregarded as a skin commensal.