Loading....
Coupon Accepted Successfully!

Microbiology

Open Flashcards

Gram Negative Coccobacilli

Question
51 out of 58
 

A 21-yrs-old student complained of malaise, low – grade fever, and a harsh cough. CXR revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student had been ill for a week. The following laboratory data were available within two days. Cold agglutinins – negative; complement fixation (Mycoplasma pneumoniae) – 1:64; viral culture – pending, but negative to date; bacterial culture of sputum on blood agar and MacConkey’s agar – normal oral florA. In order to confirm the diagnosis, which of the following procedures could be ordered to achieve a specific and sensitive diagnosis?



A A DNA probe to the 165 ribosomal RNA of an organism lacking a cell wall

B Another viral culture in one week

C A repeat CF test in five days

D A repeat cold agglutinin test

Ans. A A DNA probe to the 165 ribosomal RNA of an organism lacking a cell wall

a. M. pneumoniae causes a respiratory infection known as primary atypical pneumonia, or walking pneumonia.

b. Until recently, diagnostic tests have been of limited value. Up to 50% of cases may not show cold agglutinins, an insensitive and nonspecific acute-phase reactant. However, if cold agglutinins are present, a quick diagnosis can be made if signs and symptoms are characteristic.

c. Complement fixation tests that measure an antibody to a glycolipid antigen of M. pneumoniae are useful but not routinely performed in most laboratories. Also, cross-reactions may occur.

d. Culture of M. pneumoniae, while not technically difficult, may take up to two weeks before visible growth is observed. A DNA probe is available. It is a 1251 probe for the 16S ribosomal RNA of M. pneumoniae.

e. Evaluations in a number of laboratories indicate that compared with culture it is highly sensitive and specific. Recently, DNA probes have been applied to the detection of M. pneumoniae in clinical specimens

Gram Negative Coccobacilli Flashcard List

58 flashcards
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
25)
26)
27)
28)
29)
30)
31)
32)
33)
34)
35)
36)
37)
38)
39)
40)
41)
42)
43)
44)
45)
46)
47)
48)
49)
50)
51)
52)
53)
54)
55)
56)
57)
58)