INFECTIOUS DISEASE CASE STUDY 24 During World War 1, soldiers injured in battle often died of then-untreatable Clostridium infections. Initial infection was usually Staphylococcus or Streptococcus. Since antibiotic therapy was not available, these initial infections might be successfully treated topically only to be replaced by one of the Clostridium organisms, usually with fatal outcomes. (A) In the first, symptoms usually occur within ten days. Initi al symptoms are restlessness, irritability, and muscular stiffness in the jaw, neck, or limbs. Muscle spasms increase, leading to clenched jaws, and stiff and arched (hyperextended) back and neck. (B) The second can develop rapidly, especially in poorly-oxygenated tissues. Typically, pain intensifies. The affected are blackens and begins to atrophy. The necrosis (death of soft tissue or bone) spreads from the site. The wound often produces and pungent, gaseous odor. Systemic effects include high fever, delirium, and shock. Laboratory Diagnosis Laboratory analysis of the affected tissue often yields such a variety of microbes that a definitive isolation of the causative agent is difficult to impossible. However, when isolation is successful, the first (A) is seen as a thin Gram positive bacillus with round terminal (at the end of the cell) endospore. It produces a thin spreading veil of growth over a blood agar plate, incubated anaerobically, indicating mobility. The second (B) is a large, gram positive, nonmotile, encapsulated bacillus. Spores are rarely seen in culture. The colonies develop rapidly and are characterized by both complete and incomplete hemolysis of blood agar in anaerobic incubation. (Extra note: This microbe has a generation time as short as 7 minutes!) Which of the following is the most likely causative agent of the infection described in (A)? C Staphylococcus aureus C. Clostridium perfringens C Clostridium tetani CClostridium difficile Which of the following is the most likely causative agent of the infection described in (B)? Clostridium difficile C Clostridium perfringens What features do these two organisms share that would account for them often appearing in deep gunshot and other battle wounds? (Mark all correct answers) They both are anaerobes and thus thrive in poorly oxygenated tissues. CClostridium tetani C Streptococcus pyogenes They both use the skin or parenteral route as portal of entry. They are both commonly found in soil. They both are members of the skin's normal flora. Which of the following is true of gangrene infection? Gas Gangrene of the abdominal cavity can be effectively treated with intravenous penicillin treatment. Gangrene can be prevented by immunization of high risk individuals. RYZEN RADEON VEGA GRAPHICS AMDT