The endotoxic activity of the gram negative bacteria is due to:

AIIMS BHOPAL NO- 2018( Shift-2nd)

Applied Microbiology & Infection control

Easy

Appeared in: AIIMS BHOPAL NO- 2018( Shift-2nd)

Explanation

Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria.
The Lipid A moiety of the LPS molecule is the actual endotoxin, responsible for its toxic effects on the host.
When Gram-negative bacteria die and lyse, Lipid A is released, triggering a potent inflammatory cascade that can lead to fever, septic shock, and disseminated intravascular coagulation (DIC).

Option A: This option is too general. While LPS is part of the cell wall, the question asks for the specific component responsible for endotoxic activity. The cell wall also contains other structures like peptidoglycan which are not the primary cause of endotoxicity.
Option B: This is a broad chemical classification. While LPS is a type of glycolipid, 'Lipopolysaccharides' is the precise and standard scientific term for the endotoxin found in Gram-negative bacteria.
Option C: Aminoglycosides are a class of antibiotics used to treat bacterial infections. They are external agents that act on bacteria; they are not a structural component of the bacteria itself.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Bacterial Virulence and Toxins as background academic context rather than a clinical decision trigger.
Understanding that LPS triggers sepsis is crucial for nurses. In patients with Gram-negative infections, nurses must diligently monitor for signs of septic shock: hypotension, tachycardia, fever, and altered mental status.
Early recognition and intervention, including prompt fluid resuscitation and appropriate antibiotic administration, are critical to prevent the progression to severe sepsis and multi-organ failure.
What if the infection was caused by a Gram-positive bacterium like Staphylococcus aureus? The primary concern would shift to exotoxins, which are proteins actively secreted by living bacteria. These can have highly specific targets (e.g., superantigens causing toxic shock syndrome), presenting a different clinical challenge than the endotoxin released upon cell death.

How to Approach the Question

First, identify the key terms in the question: 'endotoxic activity' and 'gram-negative bacteria'.
Recall the unique structure of the Gram-negative cell wall, which features an outer membrane not present in Gram-positive bacteria.
Differentiate between the components of the Gram-negative cell wall. Remember that the outer membrane contains a specific, complex molecule responsible for its toxic properties when the cell is destroyed.
Evaluate the options based on this knowledge. 'Cell wall' is too broad. 'Aminoglycosides' are drugs, not bacterial parts. 'Glycolipids' is a general chemical class.
Conclude that 'Lipopolysaccharides' is the most specific and accurate term for the molecule responsible for endotoxic activity in Gram-negative bacteria.

Concept Tested & Keywords

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