The Lowenstein Jenson medium is a culture medium for the growth of?

CGHS SSC - 2018

Microbiology

Easy

Appeared in: CGHS SSC - 2018

Explanation

Lowenstein-Jensen (LJ) medium is a selective medium specifically designed for the isolation and cultivation of Mycobacterium species.
It contains malachite green, a dye that inhibits the growth of most other bacteria and fungi commonly found in clinical samples like sputum.
The medium is egg-based (containing coagulated hen's eggs), providing the necessary nutrients like fatty acids and proteins for the slow-growing M. tuberculosis.
Colonies of M. tuberculosis on LJ medium are characteristically described as 'rough, tough, and buff' (dry, irregular, and cream-colored) and take several weeks to appear.

Option A: Clostridium species are typically obligate anaerobes and require special anaerobic media for growth.
Option C: E. coli is a non-fastidious, gram-negative bacterium that grows readily on many simple media. LJ medium is too inhibitory for it.
Option D: Staphylococcus is a gram-positive bacterium. While it can grow on basic media, specific selective media are used for its identification.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Microbiological Culture Media: Lowenstein-Jensen Medium as background academic context rather than a clinical decision trigger.
Understanding the correct culture medium is fundamental for nurses in ensuring proper specimen handling and anticipating laboratory results for infectious diseases like tuberculosis.
Nurses play a key role in patient education for sputum collection, ensuring a high-quality sample is obtained to maximize the chances of a correct diagnosis, thereby preventing delayed treatment and further transmission.
What if? If a culture from a respiratory specimen shows rapid growth (within 24-48 hours) on a standard medium like blood agar, it would strongly suggest a bacterial pneumonia caused by organisms like Streptococcus pneumoniae or Haemophilus influenzae, rather than the slow-growing M. tuberculosis.

How to Approach the Question

First, identify the core subject of the question, which is a specific type of microbiological culture medium: 'Lowenstein Jenson medium'.
This is a factual recall question. Access your knowledge base about common culture media used in diagnostic microbiology.
Recall or deduce the specific purpose of LJ medium. Its unique name and composition (egg-based, with malachite green) are strong clues that it's for a specific, fastidious organism.
Associate LJ medium with Mycobacterium tuberculosis, a notoriously slow-growing and difficult-to-culture bacterium.
Evaluate the options provided. Eliminate the other bacteria based on their standard culture requirements (Clostridium - anaerobic, E. coli - MacConkey, Staphylococcus - MSA).
Confirm that Mycobacterium tuberculosis is the correct match for Lowenstein-Jensen medium.

Concept Tested & Keywords

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