Inhibiting Microbial Growth in Vitro: Matching Terms

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Questions and Answers

What method involves reducing microbial populations to safe levels by public health standards?

Disinfection

Sterilization

Disinfectant

Pasteurization (correct)

Which term refers to the complete destruction of all microbes, including cells, spores, and viruses?

Pasteurization

Disinfection

Sterilization (correct)

Disinfectant

What is the term for chemical substances that eliminate pathogens on inanimate objects?

Pasteurization

Disinfection (correct)

Sterilization

Antiseptic

Which method involves the destruction or elimination of most pathogens from nonliving objects by physical or chemical methods?

Disinfection Signup and view all the answers

What term refers to solutions used to disinfect skin and other living tissues?

Antiseptic Signup and view all the answers

Which method involves the complete destruction of all microbes, including cells, spores, and viruses?

Sterilization Signup and view all the answers

What is the purpose of the biological indicators used in autoclaving?

To verify the autoclave cycle was successful in killing heat-resistant bacteria Signup and view all the answers

What is the primary reason for improper maintenance of the autoclave equipment?

To ensure the autoclave reaches the desired temperature and pressure Signup and view all the answers

What is the primary purpose of loosening screw caps on bottles and tubes of liquids before autoclaving?

To allow for the expansion of the liquid during the sterilization cycle Signup and view all the answers

What is the primary reason for waiting 10 minutes after opening the autoclave door before removing liquids?

To prevent the liquids from boiling over and causing burns to the operator Signup and view all the answers

What is the primary purpose of wearing eye and face protection, as well as heat-resistant gloves, when operating an autoclave?

To comply with workplace safety regulations and prevent potential injuries to the operator Signup and view all the answers

What is the primary reason for ensuring the autoclave has been properly serviced?

To ensure the autoclave reaches the correct temperature and pressure for sterilization Signup and view all the answers

Which characteristic is NOT an ideal characteristic of antimicrobial agents?

Induces allergic reactions in the host Signup and view all the answers

Which antibiotic is classified based on its mode of action as targeting the cell wall of bacteria?

Polymyxins Signup and view all the answers

Which antibiotic originates from Penicillium molds?

Penicillin Signup and view all the answers

What is a commonality among Beta-lactam antibiotics?

Having a Beta-lactam ring Signup and view all the answers

Which antibiotic group can be bacteriostatic or bactericidal depending on concentration?

Aminoglycoside Signup and view all the answers

Which antibiotic group focuses on inhibiting protein synthesis in bacteria?

Tetracycline Signup and view all the answers

Which bacteria can easily spread in hospital settings and are resistant to Methicillin and Vancomycin?

MRSA Staphylococcus aureus Signup and view all the answers

Which bacteria are the indigenous flora, but proliferate due to antibiotic treatment and cause hospital-associated diarrhea?

C. difficile Signup and view all the answers

Which type of drug resistance in bacteria involves the acquisition of genes that destroy or inactivate drugs?

Acquisition of resistance genes that destroys or inactivates drugs Signup and view all the answers

Which bacteria are members of the Enterobacteriaceae family and produce special types of beta-lactamases that inactivate Carbapenems?

CRE Enterobacteriaceae Signup and view all the answers

Which bacteria are resistant to two common drugs used to treat tuberculosis (Isoniazid and Rifampin), and some strains are resistant to almost all drugs?

MDR-TB Signup and view all the answers

What is the most important strategy to combat drug resistance in bacteria, according to the text?

Educating healthcare providers and the public Signup and view all the answers

What is the primary factor that determines the effectiveness of heat for sterilization?

Temperature and time Signup and view all the answers

Which of the following is NOT a form of heat sterilization mentioned in the text?

Microwave heat Signup and view all the answers

What is the typical pressure and temperature used in an autoclave for sterilization?

15 psi, 121°C Signup and view all the answers

Which of the following types of microorganisms can be effectively destroyed by autoclaving at the specified conditions?

Vegetative microorganisms, bacterial endospores, and viruses Signup and view all the answers

What is the purpose of quality control (QC) in the autoclaving process?

To ensure that the sterilization process is effective in killing all microorganisms Signup and view all the answers

Which of the following is NOT mentioned as a method of quality control for autoclaving?

Spectroscopic analysis Signup and view all the answers

Study Notes

Methods of Microbial Control in Vitro

Microbial control involves methods of inhibiting microbial growth, inhibition, and destruction
Methods of microbial control can be categorized into physical, chemical, and biological methods

Sterilization, Disinfection, and Antiseptics

Sterilization: the complete destruction of all microbes, including cells, spores, and viruses
Disinfection: the destruction or elimination of most pathogens from nonliving objects by physical or chemical methods
Antiseptics: chemical substances used to disinfect skin and other living tissues
Pasteurization: a method of reducing microbial populations to levels considered safe by public health standards

Heat Sterilization

Heat is a practical, efficient, and inexpensive method of sterilization for inanimate objects
Two factors determine the effectiveness of heat for sterilization: temperature and time
Thermal death point (TDP) is the lowest temperature that will kill all organisms in a standardized pure culture within a specified time
Dry heat: uses flame and incineration; moist heat: uses autoclave

Autoclave

Autoclave is a common method of sterilization used in places where sterile items are required, such as tattoo parlors, microbiology labs, and medical facilities
Autoclave uses pressure and steam to sterilize items, with typical specifications of 15 psi, 121°C, and 15-20 minutes
Autoclaving destroys vegetative microorganisms, bacterial endospores, and viruses
Quality control is essential to ensure that items are properly sterilized

Autoclave Quality Control

Chemical indicators: temperature-sensitive tapes or bags
Physical indicators: alloys that melt when exposed to correct temperature for at least 15 minutes
Biological indicators: sealed ampules with heat-resistant bacteria

Common Faults in Autoclave Operation

Inadequate precleaning of instruments
Improper maintenance of equipment
Cycle time too short or temperature too low
Overloading or improper loading of sterilizer chamber
Incompatible packaging material
Interruption of sterilization cycle to add or remove an item
Wrong cycle was selected
Mechanical failure or insufficient water supply

Autoclave Safety

Loosen screw caps on bottles and tubes of liquids before autoclaving
Always check that chamber pressure has returned to zero before opening door
Wear eye and face protection and heat-resistant gloves
Stand behind door when opening it
Slowly open door only a crack to allow residual steam to escape

Physical Methods of Inhibition

Cold can have a static effect, halting growth
Some methods preserve, such as penicillin produced by Penicillium mold

Antibiotics

Ideal characteristics of antimicrobial agents:
- Kills or inhibits growth of target pathogen
- Causes no damage to host
- No allergic reaction in the host
- Stable when stored in solid or liquid form
- Penetrates and remains in target tissue
- No resistance
Antibacterial agents can be organized by mode of action:
- Cell wall: beta-lactams
- Protein synthesis: glycopeptides
- Genetic material: quinolones
- Cell membrane: polymyxins
- Metabolic process: sulfonamides and trimethoprim

Beta-Lactam Antibiotics

Commonalities: beta-lactam ring, target cell wall, and are bactericidal
Differences: side groups, specificity, and spectrum
Examples: penicillin, cephalosporin, and carbapenems

Mechanisms of Drug Resistance

Intrinsic resistance
Mutations:
- Chromosomal mutation that alters drug-binding site
- Chromosomal mutation that causes a change in cell membrane permeability
Acquisition:
- Of resistance genes that destroy or inactivate drugs
- Of genes that pump antimicrobials outside the cell

Strategies to Combat Drug Resistance

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Description

Test your knowledge on the methods of microbial control in vitro, inhibition and destruction, use of antibiotics for controlling growth, and understanding antimicrobial resistance. Match the terms to their definitions accurately.