Select a Community
Are you sure you want to trigger topic in your Anconeus AI algorithm?
You are done for today with this topic.
Would you like to start learning session with this topic items scheduled for future?
Clumping of red blood cells after the patient’s blood is drawn and transferred into a chilled EDTA-containing vial
57%
171/301
Elevated pH of urine noted on standard urinalysis
2%
7/301
Alpha hemolysis and optochin sensitivity noted with colonies of the causative organism visualized on blood agar
6%
17/301
Clumping of red blood cells after the patient’s blood is drawn and transferred into a tube containing Proteus antigens
Causative organism is visualized with India ink stain and elicits a positive latex agglutination test
24%
72/301
Select Answer to see Preferred Response
This patient is likely suffering from atypical pneumonia due to Mycoplasma pneumoniae infection. Mycoplasma pneumoniae is not visualized on Gram stain due to its lack of cell wall and is a common cause of atypical pneumonia, especially in younger patients (military recruits and college dorm residents most commonly). A positive cold agglutinins test (as described in the preferred response) is associated with Mycoplasma pneumoniae infection. Cold agglutinins are antibodies directed against antigens on the surface of Mycoplasma pneumoniae. These antibodies cross-react with certain antigens that are also present on the surface of red blood cells. In a process mediated by these antibodies, clumping or agglutination of erythrocytes only occurs at low temperatures. The anemia that is often associated with Mycoplasma pneumoniae infection is likely due to the presence of cold agglutinins in circulation. A positive cold agglutinin test can also be seen in the settings of Epstein-Barr virus or certain hematologic cancers. Thibodeau and Viera review the microbiology and management of atypical pneumonia. Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila are atypical organisms that are the causative microbe in an estimated 40% of cases of community-acquired pneumonia. Empiric antibiotic treatment is indicated and typically covers both typical and atypical organisms. Jacobs discusses the utility and limitations of cold agglutinin testing in diagnosing Mycoplasma pneumoniae infection. Mycoplasma pneumoniae infections can be confirmed with serological methods; however, serologic parameters are often negative during the acute phase of M. pneumoniae disease. This is true for both cold hemagglutinin (the first, nonspecific acute-phase marker that is positive in only 50% of cases) as well as assays that test for more specific IgM antibodies that appear relatively early in the disease course. Illustration A depicts a chest radiograph demonstrating the bilateral diffuse interstitial infiltrate seen in atypical pneumonia. Incorrect answers: Answer 2: This response is a finding characteristic of urease containing organisms (Proteus, Klebsiella, H. pylori, Ureaplasma); these organisms do not cause atypical pneumonia. Answer 3: This response is consistent with Streptococcus pneumoniae, a cause of more overt "typical" pneumonia. Answer 4: This finding is indicative of a Rickettsial infection. Answer 5: This is a characteristic finding of infection with Cryptococcus neoformans.
4.0
(5)
Please Login to add comment