Microbiology Clinical diphtheria is caused by: (PGI June 2009) A Corynebacterium diphtheriae B Corynebacterium parvum C C. Ulcerans D Streptococcus pyogens 💡 Explanation Clinical diphtheria is caused by: (PGI June 2009) ✓ Correct Answer: A. Corynebacterium diphtheriae