L2: CONTROLLING MICROBIAL GROWTH Flashcards
purpose is to destroy all microorganisms and their spores on inanimate objects
Sterilization
purpose is to destroy or irreversibly inactivate microorganisms (but
not their spores) on inanimate objects
Disinfectant
chemical germicide for use on the skin or tissues and should not be
substituted for disinfectant
Antiseptic
inhibits/ suppresses growth of bacteria
Bacteriostatic
kills bacteria
Bactericidal
Kills microorganisms by denaturing/coagulating their proteins and enzymes
Sterilization by Heat
minimum time it takes to kill a population of
microbes at a specific temperature
Thermal Death Time (TDT)
- lowest temperature that is required to kill a population of microbes when applied for a specific time.
Thermal Death Point (TDP)
Time in minutes at which 90% of bacteria is killed within a given period of time. 🡪 canning industry
Decimal Reduction Time (DRT)
Kills vegetative forms of bacteria (water-borne), most virus, and fungi within
1 minute
Boiling
Hepatitis virus can survive up to __ minutes of boiling
30 minutes
Endospores can survive up to __minutes of boiling
20 minutes
Temperatures of about 160C for 60minutes – necessary to kill most spores
Dry heat
Most effective method of sterilization (Autoclave)
Moist Heat
Moist Heat 2 methods:
- Tyndallization
- Autoclaving
AKA Fractional sterilization
Tyndallization
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
Tyndallization Uses____ Sterilizer
Arnold Sterilizer
Most reliable method of heat sterilization, More modern, Use to sterilize culture media and surgical supplies
Autoclave
AUTOCLAVE - __C, __min, __lbs pressure
121C, 15min, 15lbs pressure
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
destroys or deactivates microorganisms and enzymes that contribute to food
spoilage or the risk of disease
Pasteurization
Types of Pasteurization
High-temperature short-time (HTST) pasteurization
Ultra-high-temperature (UHT) pasteurization
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
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)
- Congenital
- Sexual
- Hand to Hand Contact
- Droplets
4 types of Indirect Route (Route of infections)
- Fomites
- Ingestion of contaminated food and water
- Airborne
- 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
