July 13, 2010

Q&A: Treatment of Atypical Pneumonia

Atypical pneumonia refers to pneumonia caused by C. pneumoniae and other bacteria including Mycoplasma pneumoniae, Legionella pneumophila and Legionella species, C. psittaci, and Coxiella burnetii.

In this article:
Atypical pneumonia by Mycoplasma pneumoniae
MCQ clinical scenario
MCQ answer
MCQ explanation

Atypical pneumonia by Mycoplasma pneumoniae

The origin of the term "atypical" in atypical pneumonia is debatable, and may refer to the fact that these organisms are not "typical" bacteria that can be identified by standard microbiologic techniques. Others suggest that atypical refers to the mild nature of the pneumonia caused by some of these organisms compared with pneumonia caused by Streptococcus pneumoniae

Mycoplasma pneumoniae is one of the smallest free-living organisms and a common bacterial respiratory tract pathogen. Upper respiratory tract infections and acute bronchitis are the most common manifestations of M. pneumoniae infection, but pneumonia can also occur. Manifestations outside the respiratory tract (eg, encephalitis, hemolytic anemia, and carditis) are rare and can occur with respiratory tract infections or independently.

MCQ clinical scenario

A 34 year old woman has an atypical pneumonia suspected to be secondary to Mycoplasma Pneumonia.

The penicillin group of antibiotics are ineffective for the treatment of pneumonia caused by Mycoplasma pneumoniae because:

a) Mycoplasma produce Beta lactamase enzyme which breaks down penicillin
b) Mycoplasma lacks a cell wall
c) Mycoplasma belong to category of viruses
d) Mycoplasma are non-sporing organisms
e) The above statement is untrue

MCQ questions & answers on medicalnotes.info

MCQ answer

The correct answer is B.
The penicillins are ineffective because Mycoplasma lacks a cell wall.

MCQ explanation

Penicillin group of antibiotics bring about their bactericidal action by selective inhibition of bacterial cell wall synthesis.

Mycoplasma are a group of bacteria which are devoid of a cell wall. Due to the absence of a cell wall these bacteria are naturally resistant to the action of penicillin group of antibiotics. Therefore penicillins are of no use for the treatment of pneumonia caused by mycoplasma pneumoniae.

Mycoplasma does not produce beta lactamase enzyme for the breakdown of penicillins. Mycoplasma are not viruses. They are classified as bacteria. The non-sporing nature of mycoplasma has no relation to their sensitivity to penicillin. A large number of non-sporing organisms are sensitive to penicillin.

Reference(s)
1). UpToDate: Mycoplasma pneumoniae infection in adults. Available online: https://www.uptodate.com/contents/mycoplasma-pneumoniae-infection-in-adults
2). UpToDate: Pneumonia caused by Chlamydia pneumoniae in adults. Available online: https://www.uptodate.com/contents/pneumonia-caused-by-chlamydia-pneumoniae-in-adults

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