Colon Cancer and Gas around the Joints! - USMLE Forums
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  #1  
Old 07-30-2012
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Bacteria Colon Cancer and Gas around the Joints!

A 69-year-old man with recurrent adenocarcinoma of the colon was admitted to the hospital with the sudden onset of excruciating pain in his left elbow. There had been no antecedent trauma. His temperature was 37.8°C (100°F), heart rate 112 beats/min and blood pressure 100/65 mm Hg. His left arm was swollen and tender, with a large purplish lesion over the elbow and crepitation around the elbow. X-ray of the arm showed gas in the deep structures surrounding the joint. Gram stain of bullous fluid revealed rare polymorphonucleocytes (PMNs) and numerous Gram-positive rods with subterminal spores, which were later recovered in both aerobic and anaerobic cultures. What is the most likely diagnosis?

a) Cellulitis due to Clostridium perfringens
b)
Myonecrosis due to C. perfringens
c)
Myonecrosis due to Clostridium septicum
d)
Necrotizing fasciitis and myositis due to Staphylococcus aureus
e)
Necrotizing fasciitis and myositis due to Streptococcus pyogenes
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  #2  
Old 07-30-2012
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Answer is C
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  #3  
Old 07-30-2012
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B : gas gangrene due to myonecrosis due to cl.perfringes


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  #4  
Old 07-30-2012
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c) Myonecrosis due to Clostridium septicum

while C. perfringens can cause the same, C. septicum is associated with malignancy (Colon cancer).
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  #5  
Old 07-30-2012
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great ques casandra .....the answer is c.myonecrois by clostridium septicum.....i was initially tempted to pick b .myonecrosis by clostridium perfringens but unlike cl.perfringens which is associated with trauma ..cl.septicum is associated with colorectal cancer
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  #6  
Old 07-31-2012
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c is the answer
http://en.wikipedia.org/wiki/Clostridium_septicum
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  #7  
Old 07-31-2012
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Correct Answer correct answer :)

The answer is c) Myonecrosis due to Clostridium septicum

The patient developed a nontraumatic gas gangrene most likely caused by C. septicum. The organism resides in appendices of up to 60% of normal individuals. C. septicum is an anaerobic rod-shaped bacterium with subterminal spore that tolerates oxygen and thus will grow on blood agar plates aerobically.

As for B) - C. perfringens myonecrosis, also known as gas gangrene, is a fulminant life-threatening disease characterized by intense pain, crepitation, and systemic toxicity. Toxins produced by C. perfringens mediate the disease. Biopsy of the muscle tissue reveals a striking absence of neutrophils and presence of large Gram-positive rods with truncated ends. C. perfringens spores are rarely seen in biopsy specimens. In addition, the patient has no history of trauma or surgery. Thus, C. perfringens is an unlikely cause of this patient’s myonecrosis.
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  #8  
Old 07-31-2012
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Thanks guys for clearing that
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Old 08-01-2012
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b) Myonecrosis due to C. perfringens
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Old 09-15-2012
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Thumbs Up C

I will go with option C
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