Tetanus infection commonly occurs in deeper wounds, for instance, wounds that reach the subcutaneous fat layer, and in severe cases, even the muscle layer. Such deep wounds can create an anaerobic environment, and Clostridium tetani, an anaerobic bacterium, thrives in this oxygen-free environment. It can secrete various bacterial toxins, thereby causing tetanus in patients. Therefore, tetanus generally occurs in deep wounds. For superficial wounds, the chance of contracting tetanus is almost zero if the wound is properly disinfected locally.