Closing the Brief Case: Ventilator-Associated Corynebacterium accolens Pneumonia in a Patient with Respiratory Failure Due to COVID-19

ANSWERS TO SELF-ASSESSMENT QUESTIONS

• 1.In which body site(s) can Corynebacterium accolens be frequently found in humans?
  • a.Urinary tract
  • b.Upper respiratory tract
  • c.Gastrointestinal tract
  • d.Genital tract

Answer: b. As an inhabitant of the upper respiratory tract, C. accolens is one of the most common Corynebacterium species isolated from the nasal cavity of healthy people.

• 2. Which of the following phenotypic characteristics fit with identification of Corynebacterium accolens?

  • a.Catalase positive and lipophilic
  • b.Catalase negative and lipophilic
  • c.Catalase positive and nonlipophilic
  • d.Catalase negative and nonlipophilic

Answer: a. The majority of medically relevant Corynebacterium species are catalase positive and nonmotile. Some Corynebacterium species, e.g., C. accolens, C. jeikeium, and C. urealyticum, are lipophilic, and growth is enhanced on media supplemented with an additional lipids.

• 3. Which of the following diagnostic tests can yield the most reliable identification of Corynebacterium accolens?

  • a.MALDI-TOF MS
  • b.CAMP reaction
  • c.Vitek 2 ID-ANC card
  • d.Serologic tests

Answer: a. Conventional biochemical methods are suboptimal for identifying C. accolens, which may be misidentified as C. macginleyi with the API Coryne test, and as Propionibacterium (Cutibacterium) acnes with the Vitek 2 ID-ANC card. MALDI-TOF MS is a robust and cost-effective tool for rapid and accurate species-level identification of Corynebacterium spp., including C. accolens.

TAKE-HOME POINTS

• •Corynebacterium accolens are aerobic, asporogenous, catalase-positive, lipophilic Gram-positive rods, which typically exhibit diphtheroid morphology.
• •As an inhabitant of the upper respiratory tract, C. accolens is one of the most common Corynebacterium species isolated from the nasal cavity of healthy people.
• •C. accolens is increasingly recognized as a medically relevant Corynebacterium species and associated with a variety of human diseases, including ventilator-associated pneumonia.
• •MALDI-TOF MS is a robust and cost-effective tool for rapid and accurate species-level identification of Corynebacterium spp., including C. accolens.
• •C. accolens isolates are generally susceptible to a broad range of antibiotics, including penicillins, ceftriaxone, gentamicin, vancomycin, and linezolid.