An agent that has the power to kill bacteria is called?

NHM UP Staff Nurse - 2019

Microbiology

Easy

Appeared in: NHM UP Staff Nurse - 2019

Explanation

A bactericide is an agent specifically designed to kill bacteria.
The term is derived from 'bacterio-' (referring to bacteria) and the Latin suffix '-cide' (meaning 'to kill').
This action is typically irreversible, leading to the death of the bacterial cell.
Examples of bactericidal agents include many antibiotics like β-lactams (e.g., penicillin) and aminoglycosides.

Option A: An antiseptic is a substance applied to living tissue to prevent infection. While some antiseptics are bactericidal, others are only bacteriostatic (inhibit growth). The term is broader and defines the use (on living tissue) rather than the specific action of killing bacteria.
Option B: A bacteriostat is an agent that inhibits bacterial growth and reproduction but does not kill the bacteria. The suffix '-stat' means to stop or keep in a stationary state.
Option C: Bacteriostasis is not an agent; it is the condition or state where bacterial growth is inhibited. It describes the effect of a bacteriostatic agent.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Microbiology Terminology: Bactericidal vs. Bacteriostatic Agents as background academic context rather than a clinical decision trigger.
Infection Control: The choice between a bactericidal and a bacteriostatic agent is critical. Bactericidal agents are essential for sterilizing surgical instruments and for treating life-threatening infections.
Patient Factors: For immunocompromised patients (e.g., those with neutropenia, HIV, or on chemotherapy), a bactericidal antibiotic is strongly preferred because their immune system cannot effectively clear the bacteria, even if their growth is inhibited by a bacteriostatic drug.
What if?: What if the infection is endocarditis (infection of the heart valves)? A bactericidal agent is mandatory. The vegetations on the heart valves are difficult for immune cells to penetrate, so the antibiotic must be able to kill the bacteria on its own.

How to Approach the Question

First, identify the key action word in the question stem, which is 'kill'.
Next, analyze the options by breaking them down into their root words and suffixes.
Recognize that the suffix '-cide' means 'to kill' (e.g., homicide, suicide).
Recognize that the suffix '-stat' or '-stasis' means 'to stop' or 'to stand still'.
Based on this linguistic breakdown, 'bactericide' directly translates to 'bacteria killer'.
Eliminate 'bacteriostat' as it only stops growth, 'bacteriostasis' as it's a condition, and 'antiseptic' as it's a broader term for use on living tissue.

Concept Tested & Keywords

Concept Tested: Microbiology Terminology: Bactericidal vs. Bacteriostatic Agents
Stem keywords: agent, kill bacteria
Lead-in keywords: is called
Negative lead-in flag: false

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E6 Pharmacology Katzung 16e pp. 1414-1416, 1394-1396

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 126-128