21-yr-old College Student with Harsh Cough

[bebix]

A 21-year-old college student complained of malaise, low-grade fever, and a harsh cough, but not of muscle aches and pains. An x-ray revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student has been ill for a week.

1.- Based on the information given, the most likely diagnosis is
a. Mycoplasma pneumonia
b. Pneumococcal pneumonia
c. Staphylococcal pneumonia
d. Influenza
e. Legionellosis

2.- Based on the information given, which of the following laboratory tests would most rapidly assist you in making the diagnosis?
a. Cold agglutinins
b. Viral culture
c. Complement fixation (CF) test
d. Gram stain of sputum
e. Culture of sputum

3.- The following laboratory data were available within 2 days: cold agglutinins—negative; complement fixation (M. 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. Culture of the sputum on charcoal yeast extract
b. A repeat cold agglutinin test
c. A DNA probe to the 16S ribosomal RNA of an organism lacking a cell wall
d. A repeat CF test in 5 days
e. Another viral culture in 1 week

[dr.muhamad]

1-a
2-a
3-c
????

[hardik221186]

1.-a
2.-a/c
3.-a/c

[dr.Irina]

1.a
2.a
3.c

[Hope2Pass]

hey just wondering, what are the right answers for these?

[eesfee]

The correct answers are:

a
a
c

[mle2resident]

I wud go for
a
a
c

[bebix]

The answers are
1-a
2-a
3-c

[amritdhillon257]

why 3-( c )..
can you explain please...

[bebix]

Originally Posted by amritdhillon257

why 3-( c )..
can you explain please...

Up to 50% of cases may not show cold agglutinin. However, if cold agglutinins are present, a quick diagnosis can be made if signs and symptoms are characteristic.
Complement fixation tests that measure an antibody to a glycolipid antigen of M. pneumoniae are useful but not routinely performed in most laboratories and cross-reactions may occur.
Culture of M. pneumoniae may take up to 2 weeks before visible growth is observed. Evaluations in a number of laboratories indicate that compared with culture, a DNA probe is highly sensitive and specific.