Chapter 4, Problem 1EDCS

Necrotizing Fasciitis

Fever, chills, nausea, weakness, and general yuckiness. Carlos thought he was getting the flu. Further, he had pulled a cactus thorn from his arm the day before, and the tiny wound had swollen to a centimeter in diameter. It was red, extremely hot, and much more painful than such a puncture had a right to be. Everything was against him. He couldn’t afford to miss days at work, but he had no choice.

He shivered in bed with fever for the next two days and suffered more pain than he had ever experienced, certainly more than the time he broke his leg. Even more than passing a kidney stone. The red, purple, and black inflammation on his arm had grown to the size of a baseball. It was hard to the touch and excruciatingly painful. He decided it was time to call his brother to take him to the doctor. That decision saved his life.

Carlos’s blood pressure dropped severely, and he was unconscious by the time they arrived. The physician immediately admitted Carlos to the hospital, where the medical team raced to treat necrotizing fasciitis, commonly called “flesh-eating” disease. This reemerging disease is caused by group A Streptococcus, a serotype of Gram-positive bacteria also known as Streptococcus pyogenes. Group A strep invades through a break in the skin and travels along the fascia-the protective covering of muscles-producing toxins that destroy human tissues, affecting about 750 people each year in the United States.

By cutting away all the infected tissue; using high-pressure, pure oxygen to inhibit bacterial growth; and applying antimicrobial drugs to kill the bacterium, the doctors stabilized Carlos. After months of skin grafts and rehabilitation, he returned to work, grateful to be alive. (For more about necrotizing fasciitis, see pp.560-561.)

1. What color do cells of S. pyogenes appear after the Gram staining procedure?