The Incorrect Association is C
The correct answer is C: Verruca vulgaris is NOT caused by HPV types 6,11,16, or 18—it is caused by HPV types 2 and 4. 1, 2
Analysis of Each Association
A. Blistering Distal Dactylitis: Streptococcus pyogenes - CORRECT
- This is a localized infection of the volar fat pad of the distal phalanx caused primarily by group A beta-hemolytic Streptococcus (Streptococcus pyogenes). 3
- Less commonly, Staphylococcus aureus and Staphylococcus epidermidis can be causative organisms. 3
- While classically described in children aged 2-16 years, it can occur in younger infants and adults. 3, 4
B. Hand, Foot, and Mouth Disease: Coxsackievirus A16 - CORRECT
- Coxsackievirus A16 is the most common cause of hand, foot, and mouth disease in the United States. 5, 6
- Enterovirus 71 is another primary causative agent, particularly associated with severe neurologic complications in Asian outbreaks. 5
- Coxsackievirus A6 has emerged as a cause of atypical and more extensive presentations, including widespread exanthema, peri-oral rash, and adult cases. 5, 7, 6
C. Verruca Vulgaris: HPV 6,11,16,18 - INCORRECT
- Verruca vulgaris (common warts) is caused by HPV types 2 and 4, NOT types 6,11,16, or 18. 1, 2
- HPV 6 and 11 cause genital warts (condyloma acuminatum), accounting for approximately 90% of genital wart cases. 1, 2
- HPV 16 and 18 are high-risk oncogenic types strongly associated with cervical dysplasia, squamous intraepithelial neoplasia, and squamous cell carcinoma. 1, 2
- The distinction between cutaneous wart-causing HPV types (2 and 4) and sexually transmitted types (6,11,16,18) is critical, as they have distinct anatomic distributions, transmission routes, and malignant potential. 1
D. Hot Tub Folliculitis: Pseudomonas aeruginosa - CORRECT
- Hot tub folliculitis is correctly associated with Pseudomonas aeruginosa infection from exposure to contaminated water in hot tubs, whirlpools, and swimming pools. 2
Key Clinical Pitfall
The most common error is conflating the HPV types that cause benign cutaneous warts (types 2 and 4) with those causing genital lesions or malignancy-associated disease (types 6,11,16, and 18). 1 These represent distinct clinical entities with different transmission patterns—verruca vulgaris occurs via autoinoculation from fingers to mouth, while HPV 6,11,16, and 18 are sexually transmitted. 1, 2