"Sorry," Jack managed. He felt embarrassed, since everyone was looking at him.

"Are you done tonight or what?" Warren questioned.

Jack shrugged. The pain had peaked, then lessened considerably, giving him a false sense of hope. Gingerly, he got to his feet and gradually put weight on the injured joint. He shrugged again and took a few tentative steps. "It doesn't feel that bad," he announced as he assessed the abrasions on his left elbow and knee. Then he tried yet another couple of steps, which seemed okay until he twisted himself to the left. At that point, the joint again briefly dislocated, causing Jack to revisit the pavement. For a second time, he struggled to his feet. "I'm done," he remarked with equal resignation and regret. "I'm really done. Clearly, this isn't a simple sprain."

LIKE MOST PEOPLE, David Jeffries had never truly appreciated the molecular marvel that bacteria represented, nor the fact that whether an infection, once started, would be contained or spread depended on the outcome of an epic molecular battle waged between the bacteria's virulence factors and the human body's defense mechanisms. He also had never truly appreciated the threat that bacteria continued to pose, despite the extensive pharmacopoeia of antibiotics available to the modern physician. He had been aware that bacteria were responsible for terrible scourges in the past, including the black plague, but that had been in the past. He certainly hadn't worried about bacteria the way he worried about viruses such as H5N1 (bird flu), Ebola, or the virus that causes AIDS, whose threat was continually hyped by the media.