Questions and Answers
What is the primary purpose of cleaning before sterilization or disinfection?
Which sterilization method effectively kills bacterial endospores?
What is the mode of action of phenols in chemical sterilization?
At what temperature and duration does dry heat sterilization typically occur?
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What is the main disadvantage of using phenolics as a sterilizing agent?
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What is the minimum temperature and time required for effective sterilization in an autoclave?
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Which method involves passing liquid or gas through a filter to sterilize?
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Which of the following methods is NOT considered a physical method of sterilization?
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What is the term used to describe the process of making something dirty or poisonous?
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Which of the following is NOT a form of decontamination?
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What level of decontamination eliminates virtually all pathogenic microorganisms except bacterial spores?
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Which factor does NOT influence the effectiveness of disinfection?
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Which process involves applying a liquid antimicrobial chemical to skin or tissue?
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What is the primary purpose of cleaning in a decontamination process?
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Which aspect is least likely to affect the level of decontamination achieved on an instrument?
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What term describes the unintentional introduction of microbial agents into the food chain?
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Which mechanism is primarily involved in the action of phenolics on plasma membranes?
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What is the primary characteristic of triclosan among disinfectants?
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What role does iodine play in antiseptic treatments?
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How does chlorine function as a disinfectant?
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Which disinfectant is most effective against Gram-positive bacteria?
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What is the primary action of alcohols in microbial control?
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What is a key drawback of using alcohol as a disinfectant?
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What is the primary function of heavy metals in microbial control?
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What is the primary mechanism of cationic detergents in microbial control?
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Which acid is mentioned as effective at controlling molds at low pH levels?
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Which of the following statements about peroxygens is true?
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What is the primary purpose of gaseous sterilants such as ethylene oxide?
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Which of the following is NOT a characteristic of acid-anionic detergents?
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Which component primarily acts through oxidation to exert antimicrobial effects?
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What is the function of the plasma membrane in microbial cells?
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Which of the following antimicrobial agents is categorized as a metabolic inhibitor?
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What is the primary action of polymyxin B in microbial control?
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Which of the following antibiotics specifically inhibits the final step of cell wall biosynthesis?
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What type of agents are classified as DNA inhibitors in antimicrobial action?
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Which statement accurately describes the mechanism of sulfanilamides?
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Which antimicrobial agent is primarily effective against Gram-positive bacteria?
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What is the primary effect of erythromycin on bacterial cells?
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What characteristic defines a substance that inhibits nucleic acid synthesis?
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Which antibiotic is known for targeting both DNA and RNA synthesis?
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Study Notes
Contamination and Decontamination
- Contamination refers to the process of making something dirty or toxic, including containing harmful substances.
- Microbial contamination occurs when harmful microorganisms like bacteria, viruses, or parasites unintentionally enter the food chain and are consumed.
- Decontamination is the process that makes medical devices, instruments, or surfaces safe to handle and involves sterilization, disinfection, and antisepsis.
Levels of Decontamination
- Disinfection: Utilizes liquid chemicals to destroy almost all pathogenic microorganisms except bacterial spores on surfaces and equipment. Effectiveness varies with organism type, organic matter, and exposure conditions.
- Antisepsis: Involves applying antimicrobial chemicals to living tissues, such as skin, to inhibit or destroy microorganisms. Common in swabbing injection sites and hand washing.
- Cleaning: Involves using water, detergent, and mechanical actions like scrubbing to remove dirt and reduce microorganisms before further decontamination.
- Sterilization: Aims to eliminate all microbial life, including resistant bacterial endospores, through physical or chemical means.
Physical Methods of Sterilization (In Vitro)
- Radiation: Utilizes short, invisible UV light for germicidal effects, effective against vegetative cells.
- Burning/Open Flame: Involves heating instruments at 65°C to cause coagulation.
- Dry Heat Oven: Operates at 160-170°C for 1-2 hours to sterilize instruments like petri dishes.
- Boiling: Applies temperatures of 100°C or higher to kill vegetative states.
- Filtration: Involves passing liquids or gases through materials with pores, such as HEPA or membrane filters.
- Autoclaving: Employs steam under pressure at 121°C for 15-20 minutes to eliminate bacteria and spores.
Chemical Methods of Sterilization (In Vitro)
- Phenols & Phenolics: Disrupt plasma membranes and denature enzymes; generally not preferred due to irritating qualities.
- Bisphenols: Effective as disinfectants in soaps; target a broad spectrum of bacteria.
- Biguanide (Chlorhexidine): Bactericidal especially against Gram-positive bacteria; used in surgical scrubs.
- Halogens: Iodine and chlorine serve as strong oxidizing agents for disinfecting water and surfaces.
- Alcohols: Denature proteins and dissolve lipids; common examples include ethanol and isopropanol.
- Heavy Metals: Use silver nitrate for microbial denaturation, effective in various applications.
- Surface-active Agents: Mechanical removal through scrubbing; includes soaps and cationic detergents for broad-spectrum activity.
Actions of Antimicrobial Drugs
- Damage to Plasma Membrane: Leads to leakage of cellular contents. Example: Polymyxin B.
- Inhibition of Cell Wall Synthesis: Protects bacteria from injury; common antibiotics include penicillin and cephalosporins.
- Inhibition of Protein Synthesis: Disrupts new protein generation; examples are chloramphenicol and erythromycin.
- Inhibition of Metabolite Synthesis: Compounds that interfere with normal metabolism. Examples include sulfanilamides and trimethoprim.
- Inhibition of Nucleic Acid Synthesis: Targets DNA and RNA production. Examples are quinolones and rifampicin.
Specific Antimicrobial Drug Actions
- Penicillin: Inhibits transpeptidase, essential for cell wall biosynthesis and effective against Gram-positive bacteria.
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Description
Test your knowledge on the concepts of contamination and decontamination processes. This quiz covers various aspects including microbial contamination, the significance of sterilization, disinfection, and antisepsis in making surfaces safe to handle. Perfect for students in health sciences or environmental studies.
