Microbial Control and Biosafety Levels

These flashcards cover key concepts related to microbial control, biosafety levels, sterilization methods, chemical agents, and techniques discussed in the lecture.

Biosafety Level 1 (BSL-1)

Lowest risk level; microbes do not cause disease in healthy individuals, minimal precautions necessary; examples include E. coli and Bacillus subtilis.

Biosafety Level 2 (BSL-2)

Moderate risk of infectious agents commonly found in clinical labs; requires PPE and biosafety cabinets; examples include Mycobacterium tuberculosis and HIV.

Biosafety Level 3 (BSL-3)

Serious or potentially lethal infections; requires respirators and strict containment protocols; examples include West Nile virus and Bacillus anthracis.

Biosafety Level 4 (BSL-4)

Highest danger; often fatal diseases with no available treatments; requires full-body suits and maximum containment.

Sterilization

The complete elimination of all life forms, including bacteria, viruses, and endospores, achieved through heat, pressure, filtration, and chemicals.

Disinfection

Elimination of most microbes on surfaces, does not kill endospores.

Antiseptics

Antimicrobial chemicals that are safe for application on skin.

Fomite

An inanimate object capable of transmitting microbes between individuals, e.g., door handles and medical equipment.

Endospores

Highly resistant bacterial structures that can survive extreme conditions such as heat and chemicals; example includes Clostridium botulinum.

Aseptic technique

Procedures that prevent contamination of sterile materials or environments, critical in labs and clinical settings.

Pasteurization

A method that reduces pathogens in foods without achieving sterility; involves different temperature-time combinations.

Autoclave standard conditions

121°C, 15 psi pressure, for 15 minutes; used for sterilization through pressurized steam.

Moist heat vs Dry heat

Moist heat (e.g., autoclaving) is generally more effective for microbial control than dry heat (e.g., incineration).

Refrigeration

Slows microbial metabolism by maintaining temperatures between 0–7°C.

Ionizing radiation

Uses gamma rays, X-rays, or electron beams to damage DNA and sterilize medical supplies.

Alcohols

Kill bacteria and fungi by disrupting membranes; commonly used as skin antiseptics.

Triclosan

Banned by the FDA in consumer antibacterial soaps due to lack of effectiveness and concerns about safety and antibiotic resistance.

Disk Diffusion Test

Method for testing the effectiveness of germicidal chemicals by measuring the zone of inhibition around antimicrobial disks.