A 56-year-old Army officer received a smallpox vaccination at a military vaccination clinic. Within 2 weeks, a painful ulcer was noted at the vaccination site. Because of the appearance of an increasing number of peripheral lesions and because of continued enlargement of the initial ulcer, he was treated. Eventual recovery was complicated by Pseudomonas sepsis and the need for a skin graft at the vaccination site. What was the cause of the ulcer and lesions, and what were the treatments? What caused the Pseudomonas infection?