One of the odder aspects of infection is that microbes that normally do no harm at all sometimes get into the wrong parts of the body and "go kind of crazy," in the words of Dr. Bryan Marsh, an infectious diseases specialist at Dartmouth-Hitchcock Medical Center in Lebanon, New Hamphire. "It happens all the time with car accidents when people suffer internal injuries. Microbes that are normally benign in the gut get into other parts of the body—the bloodstream, for instance—and cause terrible havoc."
感染有许多古怪的方面。其中之一是，有些在正常情况下完全无害的微生物，有时候会进入人体本来不该它们去的部分——用新罕布什尔州莱巴嫩城达特茅斯-希契科克医疗中心的传染病专家布赖恩·马什的话来说——“有点儿发了狂”。“这种总是出现在发生了车祸，有人受了内伤的时候。通常情况下肠胃里面无害的微生物就会进入身体的其他部分——比如流动的血液，产生严重的破坏作用。”

The scariest, most out-of-control bacterial disorder of the moment is a disease called necrotizing fasciitis in which bacteria essentially eat the victim from the inside out, devouring internal tissue and leaving behind a pulpy, noxious residue. Patients often come in with comparatively mild complaints—a skin rash and fever typically—but then dramatically deteriorate. When they are opened up it is often found that they are simply being consumed. The only treatment is what is known as "radical excisional surgery"—cutting out every bit of infected area. Seventy percent of victims die; many of the rest are left terribly disfigured. The source of the infection is a mundane family of bacteria called Group A Streptococcus, which normally do no more than cause strep throat. Very occasionally, for reasons unknown, some of these bacteria get through the lining of the throat and into the body proper, where they wreak the most devastating havoc. They are completely resistant to antibiotics. About a thousand cases a year occur in the United States, and no one can say that it won't get worse.
眼下，最罕见的也是是无法控制的细菌引起的疾病，是一种会导致坏死病的筋膜炎。细菌吞噬内部组织，留下一种糨糊状的有毒残渣，实际上把病人从里到处吃掉。起初，病人往往只是稍有不舒服——通常是身上出疹，皮肤发热——但接着就急剧恶化。打开一看，往往发现病人正被完全吃掉。唯一的治疗办法是所谓的“彻底切除手术”——即把所有感染部位全部切除。70%的病人死亡，许多幸存者最后严重毁形。感染原是一种名叫A群链球菌的普通细菌家族，通常不过引起链球菌咽喉炎。在极少的情况下，由于不明原因，这类细菌有的会钻进咽喉壁里，进入人体本身，造成最严重的破坏作用。它们完全能抵御抗生素。这种情况美国每年发生大约1000例，谁也说不准情况是不是会变得更严重。