L2: CONTROLLING MICROBIAL GROWTH Flashcards by JD Dela Cruz

purpose is to destroy all microorganisms and their spores on inanimate objects

Sterilization

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purpose is to destroy or irreversibly inactivate microorganisms (but
not their spores) on inanimate objects

Disinfectant

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chemical germicide for use on the skin or tissues and should not be
substituted for disinfectant

Antiseptic

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inhibits/ suppresses growth of bacteria

Bacteriostatic

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kills bacteria

Bactericidal

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Kills microorganisms by denaturing/coagulating their proteins and enzymes

Sterilization by Heat

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minimum time it takes to kill a population of
microbes at a specific temperature

Thermal Death Time (TDT)

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lowest temperature that is required to kill a population of microbes when applied for a specific time.

Thermal Death Point (TDP)

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Time in minutes at which 90% of bacteria is killed within a given period of time. 🡪 canning industry

Decimal Reduction Time (DRT)

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Kills vegetative forms of bacteria (water-borne), most virus, and fungi within
1 minute

Boiling

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Hepatitis virus can survive up to __ minutes of boiling

30 minutes

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Endospores can survive up to __minutes of boiling

20 minutes

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Temperatures of about 160C for 60minutes – necessary to kill most spores

Dry heat

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Most effective method of sterilization (Autoclave)

Moist Heat

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Moist Heat 2 methods:

Tyndallization
Autoclaving

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AKA Fractional sterilization

Tyndallization

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Tyndallization- the steaming process performed at 100°C done in steam sterilizer for 15-20 minutes followed by incubation at 37°C overnight and this cycle is repeated
for successive __ days

3 days

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Tyndallization Uses____ Sterilizer

Arnold Sterilizer

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Most reliable method of heat sterilization, More modern, Use to sterilize culture media and surgical supplies

Autoclave

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AUTOCLAVE - __C, __min, __lbs pressure

121C, 15min, 15lbs pressure

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process of food preservation in which packaged and unpacked foods (e.g.,
milk and fruit juices) are treated with mild heat, usually to less than 100 °C
(212 °F), to eliminate pathogens and extend shelf life

Pasteurization

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destroys or deactivates microorganisms and enzymes that contribute to food
spoilage or the risk of disease

Pasteurization

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Types of Pasteurization

High-temperature short-time (HTST) pasteurization
Ultra-high-temperature (UHT) pasteurization

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for milk; (71.5 °C
(160.7 °F) for 15 seconds) which ensures safety of milk and provides a
refrigerated shelf life of approximately two weeks

High-temperature short-time (HTST) pasteurization

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milk is pasteurized at 135 °C (275 °F) for 1–2 seconds, which provides the same level of safety, but along with the packaging, extends shelf life to three months under refrigeration

Ultra-high-temperature (UHT) pasteurization

UV rays with shorter WL are more effective in killing bacteria

Irradiation

______ with WL 240 -280 ARE used to sterilize rooms

Mercury vapor lamps with WL 240-280

Use if heat is not feasible (some carbohydrates solutions, serum, body fluids), Removes microbes by passage of liquid or gas through a screen like material with small pores

Filtration

A typical microfiltration membrane pore size range is ___ - ___ µm, with the most commonly used being 0.2 µm and 0.45 µm, which is sufficient to eliminate bacteria and fungi

0.1-10 µm

use in operating rooms to eliminate bacteria; mostly filters particles that are 0.3um; capture pollen, dirt, dust, moisture, bacteria (0.2–2.0 μm), viruses (0.02–0.3 μm), and submicron liquid aerosol (0.02–0.5 μm).

High Efficiency Particulate Air filter (HEPA)

usually inhibit or stop microbial growth and proliferation but often do not kill bacteria (BACTERIOSTATIC)

Low Temperature

three types of alcohol are ___, ___, and ___

ethanol, methanol, and isopropanol

works by denaturing and coagulating proteins, disrupting their cell wall, and killing them; dissolves lipid membranes, highly efficient against viruses and can be used in adjunct with other ___ to obtain a powerful synergistic effect against microorganisms

Alcohol

EXAMPLE OF Oxidizing Agents

H2O2, K-permanganate

act by oxidizing the cell membrane of microorganisms, which results in a loss of structure and leads to cell lysis and death

Oxidizing Agents

Disrupts oxidative phosphorylation, which is the most important process in cell ex. Iodide, Chlorines

Halogens

Porous surface- __:__dilution

1:10 dilution

Hard Surfaces- _:___ dilution

1:100 dilution

Concentrated infectious agents: __:__ dilution

1:5 dilution

produce saponification of the fatty acids within cell membranes, resulting in the loss of membrane integrity. ex KOH, NaOH

Alkalies

disrupts the amphoteric matter in microbial surface structures and increases the permeability of cell membrane, subsequently metabolic processes are hindered

Acids

inactivates microorganisms by alkylating the amino and sulfhydral groups of proteins and ring nitrogen atoms of purine bases. ex. Formaldehyde

Gases

ex. hexadecyltrimethylammonium ('cetrimide'), chlorhexidine, and benzalkonium chloride

Quaternary Ammonium Compounds

bactericidal and fungicidal activity, permeate into the membrane and disrupt its physical and biochemical properties

Quaternary Ammonium Compounds

disrupt the chemical bonds that allow bacteria, viruses and grime to stick to surfaces, lifting them off the skin

Soaps

Antimicrobial soaps 🡪

triclosan and triclocarban

Any chemical use to treat an infections either by inhibiting or killing pathogens. Antibacterial, Antifungal, Antiprotozoals, Antiviral

Antimicrobial Agents

subs produced by microorganism that is effective in killing or inhibiting growth of microorganisms

Antibiotics

All antibiotics are ___ but not all ___ are antibiotics

antimicrobial

trap bacteria with the assistance of cilia

Mucus

present in respiratory secretions lyses bacterial cell wall

Lysozymes

possess hydrolytic enzymes that breakdown bacteria

Saliva

destroys bacteria that are acid labile

Gastric acid of the stomach

Host Defense Mechanisms, ______ of the Large intestines

Normal flora

Host Defense Mechanisms, ____ of the urine and constant flushing action

Acidic pH

Host Defense Mechanisms, _____ lactic acid – normal flora

Vaginal lactic acid

Host Defense Mechanisms, ____ -constant flushing action

Eye tears

total changes occurring in tissue factors upon injury

Inflammation

Human Immunoglobulins, passive immunity for newborns, mainly involved in secondary (amnestic) immune response

IgG

Human Immunoglobulins, mainly involved in primary immune response

IgM

Human Immunoglobulins, prevention of bacterial and viral invasions of mucous membranes

IgA

Human Immunoglobulins, little is known, may serve as a B cell receptor or play a role in autoallergic diseases

IgD

Human Immunoglobulins, Major role in allergic response

IgE

infection Acquired in the hospital or other health care setting

Nosocomial Infection

Nosocomial Infection 2 Categories:

Endogenous Exogenous

infection: result from organisms that are part of the patient’s NF

Endogenous

infection: from external sources (contamination, inanimate objects)

Exogenous

presence and multiplication of microorganisms within a host with no clinical signs of infections 🡪 Reservoir

Colonization

– the entrance and multiplication of a microorganism in a host

Infection

condition assoc with functional and structural harm to the host 🡪 s/s

Infectious Disease

5 Common Nosocomial Infections

UTI Surgical wound infections LRTI Bacteremia Aspiration Pneumonia

6 Common Pathogens causing NI

S. aureus E. coli P. aeruginosa Coagulase negative Staph Enterococcus Klebsiella

Routes of Infection, 2 types: __ and __

DIRECT and INDIRECT

Direct Route, ____ :across the placenta (Syphillis) or through the vaginal canal (Gonorrhea)

Congenital

Direct Route, ____ :common colds, skin infections, GI pathogens

Hand to Hand contact

Direct Route, ____ :Strep throat, common colds, URTI

Droplets

4 types of Direct Route (Route of infections)

1. Congenital 2. Sexual 3. Hand to Hand Contact 4. Droplets

4 types of Indirect Route (Route of infections)

1. Fomites 2. Ingestion of contaminated food and water 3. Airborne 4. Animal or Arthropod vectors

JCAHO means

Joint Commission on Accreditation of Healthcare Organizations

CAP means

College of American Pathologists

Publication of standards for Bloodborne Pathogens, what org

OSHA - Occupational Safety and Health Administration

describe the handling of clinical specimens where BLOOD and other body fluids should be treated as INFECTIOUS

UNIVERSAL PRECAUTIONS –

is a significant part of the Universal Precaution

Personal Protective Equipment

Biosafety level: no known pathogenic potential for immunocompetent individuals, ex: Bacillus subtilis

Biosafety Level 1

Biosafety level: level 1 practices plus lab coats, protective gloves, limited acess, decontamination of all infectious waste, and biohazard warning signs. ex. HBV, HIV, Staphylococcus, etc

Biosafety level 2

Biosafety level: level 2 procedures plus special lab clothing and controlled access. ex. mycobacterium tuberculosis, Brucella, Coccidioides immitis, etc

Biosafety Level 3

Biosafety level: level 3 practices plus entrance through separate room where street clothing is changed and replaced with lab clothing ex. Filovirus and Arenavirus.

Biosafety Level 4

an enclosed, ventilated laboratory workspace for safely working with materials contaminated with (or potentially contaminated with) pathogens requiring a defined biosafety level.

Biological Safety Cabinets

what class of bsc provides protection for the user and surrounding environment, but no protection for the sample being manipulated

Class I BSC

what class of bsc sterilize both the air entering and circulating the cabinet and exhaust air, USED BY MOST HOSPITAL MICROBIOLOGICAL LABORATORIES,

Class II BSC

Class II BSC is also known as

LAMINAR FLOW

what class of bsc provides the highest level of safety, All air entering and leaving the cabinet is STERILIZED with HEPA filter, System is entirely closed and all infectious material are handled with rubber gloves that are sealed to the cabinet

Class III BSC