ANSWERS TO SELF-ASSESSMENT QUESTIONS
Which of the following are considered enterohepatic Helicobacter species?
A. Helicobacter pylori
B. Helicobacter cinaedi
C. Helicobacter canis
D. B and C
Answer: D. Helicobacter cinaedi and Helicobacter canis are both enterohepatic Helicobacter species, but Helicobacter pylori is not.
Which of the following is considered unreliable for identification of H. cinaedi?
A. 16S rRNA gene sequencing
B. Biochemical methods
C. MALDI-TOF mass spectrometry
D. Species-specific PCR
Answer: B. Because of biochemical similarities between Campylobacter species and H. cinaedi, traditional biochemical methods are not reliable for identification of H. cinaedi.
Based on published susceptibilities of H. cinaedi, which drug is most likely to have potent activity against this bacterium in vitro?
A. Ciprofloxacin
B. Levofloxacin
C. Tetracycline
D. Clarithromycin
Answer: C. Tetracycline shows potent in vitro activity against H. cinaedi. In contrast, H. cinaedi often demonstrates high MICs to fluoroquinolones (e.g., ciprofloxacin, levofloxacin, etc.) and macrolides (e.g., clarithromycin).
TAKE-HOME POINTS
Helicobacter cinaedi is an enterohepatic Helicobacter that can cause recurrent bacteremia.
There appear to be differences between commercial blood culture systems in their ability to recover H. cinaedi from blood.
While H. cinaedi can grow on routine primary media (i.e., TSA with sheep blood and chocolate agars) and enriched media (e.g., BCYE and BHI-B), growth of this bacterium on solid culture media requires extended incubation under microaerobic conditions (5 to 7% O2, 7 to 10% H2, 80 to 85% N2).
Identification of H. cinaedi using biochemical methods can be unreliable, with definitive identification best achieved using PCR or 16S rRNA gene sequencing. MALDI-TOF mass spectrometry is a promising method for the identification of this bacterium.
See page 5 in this issue (https://doi.org/10.1128/JCM.02936-15 ) for case presentation and discussion.
- Copyright © 2016 American Society for Microbiology.
