Term
| Normal resident flora (biota) |
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Definition
refers to large array of microorgs that favorably inhabit the human body in abundance
A) Total cells in human body = 1013
B) Total bacteria in the mouth = 1010
C) Total bacteria on the skin = 1012
D) Total bacteria in the G.I. tract = 1014 |
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Term
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Definition
A) Microbes accumulate over time immediately following birth by simple interaction w/ environment
B) Microbes are found almost everywhere on & in body but more prominent in locations exposed to environment (skin & GI tract)
C) Levels of specific microbes can fluctuate a great deal up & down but normally stay relatively constant
1) Competition w/ other organisms & repeated interaction w/ environment play a role in this balance
D) Some pathogens can be found in normal flora but generally don’t cause
problems BC competition limits their growth
1) In compromised state,can cause problems = opportunistic pathogens
E) The flora even plays a role in the body’s defense by producing antibodies & inhibiting entry & growth of other pathogens |
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Term
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Definition
A) The uterus is normally sterile during development
B) As fetal membrane breaks, microbes in the vagina can enter womb & begin to colonize the skin
C) During the birth the baby is exposed to an even larger # of microbes
D) Colonization of resp. system begins w/ the baby’s first breath
E) Exposure continues as baby comes into contact w/ mother, other family,
hospital staff, etc.
F) Colonization of intestines begins during first feeding
1) The microbes vary dependent on whether the baby is bottle or breast fed
G) Stabilization of eventual adult flora occurs following weaning, the intro of solid food, & eruption of teeth |
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Term
| Flora of specific regions |
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Definition
1. Skin
2. GI tract
3. Respiratory tract
4. Urogenital tract |
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Term
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Definition
A) Flora resides on or in the skin layer
B) Dryness of the skin, humidity, occupational exposure, & clothing influence make-up of flora
C) A very rich flora community is located at regions where the skin joins w/ the mucus membrane
D) 2 distinct populations: transient & resident |
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Term
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Definition
a) clings to the surface but doesn’t usually grow there
b) acquired during routine exposure to the environment or other people
c) is drastically influenced by hygiene |
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Term
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Definition
a) inhabits deeper portions of the epidermis and in glands and follicles
b) population is more stable and predictable and less influenced by hygiene
c) primarily composed of bacteria (usually Staphylococcus sp.) & fungi (Candida albicans) |
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Term
| Flora of mouth & esophagus |
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Definition
| 1) Streptococcus species is most common |
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Term
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Definition
| Helicobacter pylori is the only known bacteria that can live in the stomach |
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Term
| flora of large intestine and rectum (enterics) |
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Definition
Almost entirely composed of anaerobes
a) Bacteroides, Fusobacterium, & Clostridium are prevalent
b) Coliforms, including E. coli, Enterobacter, and Citrobacter are found in smaller numbers
i) coliforms – Gram-negative, lactose-fermenting, facultative anaerobic bacteria found in the colon
ii) Contribute to intestinal odor & discomfort caused by lactose intolerance |
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Term
| Flora of respiratory tract |
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Definition
A) Primarily seen in upper respiratory tract and varies in different regions of the respiratory pathway
1) nasal entrance – Staphylococcus
2) nasopharynx – Neisseria
3) oropharynx – Streptococcus
4) laryngopharynx & tonsils –Haemophilus
B) Conditions in the lower respiratory tract are unfavorable for permanent residents |
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Term
| Flora of urogenital tract (urethra) |
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Definition
1) Usually sterile but can sometimes find nonpathogenic Streptococci,
Staphylococci, & occasionally coliforms
2) The shorter female urethra contributes to increased susceptibility to urinary tract infections (UTI’s) |
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Term
| flora of the urogenital tract (vagina) |
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Definition
1) Before puberty
a) Staph, Strep & Candida are common
b) pH is about 7
2) After puberty
a) Estrogen causes the vaginal mucosa to secrete glycogen which is fermented
by bacteria releasing lactic acid
b) pH lowers to about 4.5
i) Thought to prevent the establishment of microbes that could be harmful to a developing fetus
c) Lactobacilli becomes prevalent bacteria; Candida is still present
3) After menopause flora & pH return pre-puberty levels |
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Term
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Definition
A) Refers to a microorganism’s potential to cause an infection or disease
1) True pathogens are microbes with the ability to cause disease in individuals with
normal immune systems
2) Opportunistic pathogens cause disease when the defenses are compromised |
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Term
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Definition
A) Properties that enable a microbe to invade and infect a host
B) Virulence
1) The ability of a microbe to cause infection that takes the presence or absence of
virulence factors into account |
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Term
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Definition
A) The characteristic route that a microbe takes to enter body tissues
1) Exogenous agents enter the body from the outside environment; ex. common cold
2) Endogenous agents already exist in the body; ex. candidiasis (yeast infection)
B) Many pathogens only cause disease when they enter through a specific portal |
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Term
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Definition
1) Most pathogens enter through damaged areas in the skin
2) Some can burrow through the skin or enter through insect bites
3) The conjunctiva is also susceptible to infection |
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Term
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Definition
1) A large number of microbes enter through the mucus membranes
2) The rectum isn’t a normal portal of entry for microbes but may become a portal with individuals who practice anal sex |
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Term
| Respiratory tract as a portal |
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Definition
| Smaller microbes are more likely to enter through this portal |
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Term
| Urogenital tract as a portal |
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Definition
1) The agents of sexually transmitted diseases and urinary tract infections (UTI’s) enter here
2) Some enter directly through the skin (broken or unbroken); others enter via the urethral mucosa or vaginal lining |
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Term
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Definition
Process by which microbes gain a more stable position in the body
a) Bacteria attach via fimbrae, flagella, pili, slime layers, capsules
b) Virus often attach to a specific receptor on the cell surface; may involve specific viral proteins (spikes)
c) Protozoa use their structures of locomotion to burrow into the host cell
d) Worms mechanically fasten using suckers, hooks or barbs |
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Term
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Definition
Often caused by a microbe’s virulence factors
1. enzymes
2. bacterial toxins |
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Term
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Definition
i) Directly inflict tissue damage
ii) Breakdown a host’s defenses and allow the microbe to move deeper into
the tissue |
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Term
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Definition
| digest the protective coating on mucus membranes |
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Term
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Definition
| digests keratin, a primary component of skin, hair, and nails |
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Term
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Definition
| digests the collagen fibers of connective tissue |
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Term
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Definition
| digests the component holding animal cells together |
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Term
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Definition
i) Toxin is any chemical that is poisonous to another organism
(a) Exotoxin – released by living bacterial cells into infected tissue
(b) Endotoxin – released when the bacteria is damaged or destroyed |
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Term
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Definition
| released by living bacterial cells into infected tissue |
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Term
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Definition
| released when the bacteria is damaged or destroyed |
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Term
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Definition
damage nervous tissue
(i) ex. tetanospasmin and anthrax toxin |
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Term
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Definition
cause symptoms associated with intestinal disturbances
(i) ex. cholera & shiga toxina |
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Term
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Definition
damage a variety of cells by damaging cell membranes or interfering with metabolism
(i) ex. streptolysin and other hemolysins |
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Term
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Definition
1) A single microbe enters the body and remains confined to a specific tissue
2) Examples: boils & fungal skin infections
3) Mixed infection
a) Several microbes establish themselves simultaneously at the infection site
b) Examples: dental caries, wound infections and human bite infections |
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Term
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Definition
1) An infection spreads to several sites and tissue fluids usually in the bloodstream
2) Examples: viral diseases such as measles, chickenpox and AIDS, and bacterial diseases such as diphtheria, typhoid fever and syphilis |
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Term
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Definition
1) A single microbe enters the body and remains confined to a specific tissue
2) Examples: boils & fungal skin infections
3) Mixed infection
a) Several microbes establish themselves simultaneously at the infection site
b) Examples: dental caries, wound infections and human bite infections |
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Term
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Definition
1) When an infectious agent breaks free of its local infection and is carried to other tissues
2) Example: tuberculosis |
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Term
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Definition
| circulation of bacteria in the bloodstream |
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Term
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Definition
| acute illness caused by bacteria or toxin in the blood (a.k.a blood poisoning) |
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Term
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Definition
the agent remains localized but its toxins are spread throughout the
body |
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Term
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Definition
| circulation of a virus in the blood |
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Term
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Definition
A) Specific route taken by pathogens to leave the host
B) Often the exit is the same as the portal of entry |
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Term
| Respiratory and salivary portals |
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Definition
1) Mucus, sputum, saliva, nasal drainage, and other moist secretions act as media for exit
2) Breathing, coughing, sneezing, laughing, and talking push these pathogens into the environment |
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Term
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Definition
1) Most individuals shed billions of dead skin cells each day and it is the largest component of household dust
2) Potential exit for the agents of fungal skin infections, syphilis, herpes simplex,
and smallpox |
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Term
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Definition
1) Common exit for intestinal pathogens and helminth worms (specifically
eggs or larva)
2) Fecal contamination of drinking water and its use as a fertilizer often raise public
health issues |
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Term
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Definition
1) Vaginal discharge/semen
a) STD’s
b) Vagina is also location of neonatal infectious agents
2) Urine
a) High acidity make is less common mode of exit but agents of typhoid fever and tuberculosis may exit in urine |
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Term
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Definition
1)no natural exit 4 blood except menses
2) Blood-feeding insects often carry pathogens from human blood
3) Shared needles & small abrasions causes by intercourse can also result in transmission of pathogens especially HIV & hepatitis |
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Term
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Definition
| microbes present at a given place and time that is undesirable |
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Term
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Definition
| the removal or destruction of contaminants |
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Term
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Definition
A) Process that removes all viable microorganisms including viruses & endospores
B) Generally applies only to inanimate objects and those essential to well-being
1) Surgical instruments, syringes, packaged foods |
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Term
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Definition
A) Refers to the use of physical or chemical means to kill vegetative pathogens and most viruses but not endospores
B) Usually only involves non-living materials due to its harsh sometimes toxic nature |
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Term
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Definition
any cleansing technique that mechanically removes microorganisms to reduce the contamination levels to acceptable
A) Washing dishes & clothes |
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Term
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Definition
reduction of the number of microbes on the human skin by scrubbing
A) Works by removing oils and microbes on the outer layer of the skin through physical or chemical means or both
1) Hand washing & surgical scrubbing
2) Swabbing with an alcohol wipe |
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Term
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Definition
| The permanent loss of reproductive capability, even under optimum growth conditions is the accepted microbial definition of death |
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Term
| Factors affecting microbial death rate |
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Definition
A) Number of microorganisms
B) Nature of the microorganisms in the target population
C) Temperature and pH of the environment
D) Concentration of the agent
E) Mode of action of the agent
F) Presence of solvents, interfering organic matter, and inhibitors |
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Term
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Definition
1. Affect the cell wall
2. Affect the cell membrane
3. Affect protein synthesis
4. Affect protein function |
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Term
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Definition
A) Block its synthesis, digest it or break down its surface
B) Makes the microbe very susceptible to lysis
C) Penicillin, cephalosporins, vancomycin, detergents, and alcohol |
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Term
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Definition
A) Disrupt the normal transport of materials in/out of the cell or allow the free flow of substances in/out of the cell
B) Surfactants – detergents that essentially open holes in the membrane |
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Term
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Definition
| detergents that essentially open holes in the membrane |
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Term
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Definition
A) Disruption of DNA transcription or replication
1) Ciprofloxacin, sulfonamides, and radiation (gamma, UV and X)
B) Disruption of translation in the ribosomes
1) Streptomycin, tetracycline, chloramphenicol, and erythromycin |
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Term
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Definition
A) Generally work by altering the protein’s natural structure (conformation)
1) Denaturation – involves the breaking of bonds within the protein to disrupt its conformation
2) Coagulation – aggregation of proteins resulting in a non-functioning mass |
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Term
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Definition
| aggregation of proteins resulting in a non-functioning mass |
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Term
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Definition
| involves the breaking of bonds within the protein to disrupt its conformation |
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Term
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Definition
A) Steam, boiling water, or hot water (pasteurization)
B) Causes protein denaturation and coagulation
C) Works well on all types of organisms although exposure time and temperature vary from microbe to microbe
1) Generally 80oC for 20 minutes is the accepted guideline for non-heat-resistant microbes |
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Term
| Steam under pressure (steam sterilization) |
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Definition
a) Steam can only reach 100 degrees under normal pressure; increasing the pressure allows for higher temps & better microbe killing
b) Destroys vegetative cells, spores, & viruses
c) Autoclave – the commercial device used for steam-heat sterilization
d) Similar in function to a pressure cooker
e) Avg settings are 15psi, 121 degrees, 15 mins
f) Effective at sterilizing heat-resistant materials glassware, cloth, metallic instruments, liquids) & any material that will be discarded(plastic Petri dishes & pipets)
g) Not effective in sterilizing substances that repel/absorb moisture(wax,oil,powder) |
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Term
| Methods of moist heat control |
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Definition
1. Steam under pressure (steam sterilization)
2. Boiling Water
3. Pasteurization (hot water) |
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Term
| Methods of physical control |
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Definition
1. Moist heat
2. Dry heat
3. Cold treatment
4. Desiccation
5. Radiation
6. Sound waves
7. Filtration
8. Osmotic pressure |
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Term
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Definition
a) Relied on for disinfection not sterilization
b) 10 minutes will kill all non-spore-forming pathogens & most viruses
c) Used by many to decontaminate suspect drinking water
d) Recontamination after removal from water is the biggest downside with
disinfection objects with this method |
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Term
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Definition
a) technique in which heat is applied to liquids to kill potential agents of
infection and spoilage while maintaining the flavor & food value
b) does not sterilize liquid as thermoduric and thermophilic orgs still remain
c) 3 methods
i) high-temp-short-time (HTST) pasteurization – 71–74 degrees for 15–30 seconds (europe,asia)
ii) batch pasteurization – 63-66 degrees for 30 minutes (USA)
iii) ultrahigh-temp (UHT)
d) Goal to prevent transmission of milk-borne diseases from infected cows & milk handlers
e) Does not kill all microbes |
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Term
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Definition
(Dry heat)
1) Uses heat to reduce the microbe to gas and ash
2) Flaming the loop in lab is an example
3) Hospitals often use incineration to eliminate their infectious waste materials |
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Term
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Definition
(Dry heat)
1) Electric coils radiate heat within an enclosed compartment
2) Sterilization occurs at 150-180 degrees for 1-4 hours
3) Used for heat-resistant materials that cannot be sterilized with moist heat (some
glassware, powders, oils, and metallic instruments) |
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Term
| Cold treatment (fridge & freezing) |
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Definition
A) Designed to slow microbial growth
B) Common in food processing and storage
C) Not considered a viable method of sterilization or disinfection |
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Term
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Definition
A) inhibits growth by removing water
B) inhibits the spread of most pathogens but not all of them
C) lyophilization – mixture of freezing & drying
1) used to preserve microbes and other cells
D) not considered a viable method of sterilization or disinfection |
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Term
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Definition
a) Excites electrons to the point that they are ejected from the molecule
i) DNA most sensitive
b)causes lethal chemical changes in organelles & the prod. of toxins
c) Used in sterilization of comm. food products
i) Potential probs: change flavor and nutritional value, & introduce undesirable chem. reactions
d) Is preferred methods for sterilizing drugs & tissues by hospitals
e) Potential danger to machine operators & possible damage to some materials are its disadvantages
f) Examples include gamma & X radiation |
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Term
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Definition
a) Excites electrons causing them to jump orbitals but don’t leave molecule
i) Leads to abnormal linkages & bonds within molecules
ii) DNA again is very susceptible
(a) thymine dimers are a common result
(b) UV radiation is the primary example
i) Excellent for disinfecting air
(a) Commonly seen in lights found in hospitals, ORs, schools, nursing homes, cafeterias, & military housing
ii) Does not pass easily through solids but is used in some applications
iii) Poses threat to human tissue if overexposure occurs |
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Term
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Definition
A) Used high-frequency sound waves to disrupt cell structure
B) Sonicator – water-filled chamber through which the sound waves become vibrations that can disrupt cell structure
C) Gram-negative bacteria are most susceptible
D) Often used to clean debris from instruments before sterilization
E) Not a reliable form of disinfection or sterilization |
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Term
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Definition
A) Used to remove microbes from air & water
B) Involves the passage of these substances through filters perforated with precise, uniform pores
1) Pore size varies dependent on what needs to be trapped but can be small enough to trap viruses
C) Used to prepare liquids that cannot withstand heat
1) Serum and other blood products, vaccines, IV fluids, and enzymes
2) Has also been used to sterilize beer and milk without altering flavor
D) Also used to capture airborne contaminants |
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Term
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Definition
(Salt concentration)
A) involves the use of salt to create a hypertonic environment
B) results in water leaving the cell, inhibiting cellular processes |
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Term
| Methods of chemical control |
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Definition
1. Phenols
2. Alcohols
3. Halogens
4. Oxidizing agents
5. Surfactants
6. Heavy metals
7. Aldehydes
8. Ethylene Oxide gas |
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Term
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Definition
A) AKA carbolic acid
B) effective against vegetative cells but not spores
C) phenolics
1) ex. orthophenylphenol (active ingredient in Lysol), hexylresorcinol (used in mouthwash), and hexochlorophene (Phisoderm)
D) they denature proteins & disrupt cell membranes
E) often have nasty odor & some side effects |
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Term
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Definition
chemicals derived from phenol that have had additional functional groups added
ex. orthophenylphenol (active ingredient in Lysol), hexylresorcinol (used in mouthwash), and hexochlorophene (Phisoderm) |
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Term
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Definition
A) effective against vegetative cells but not spores
B) isopropanol & ethanol are most commonly used in 70-90% mixtures
C) work by denaturing proteins & disrupting cell walls & membranes
D) one disadvantage is that they evaporate quickly & may not be in contact with the microbe long enough to be effective |
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Term
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Definition
A) effective against vegetative cells and some spores
B) although unclear, it is believed they disrupt enzyme function
C) ex. iodine, chlorine, bromine and fluorine |
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Term
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Definition
A) especially effective against anaerobic organisms
B) are also used to treat drinking water and to eliminate spores on open surfaces
C) work by oxidizing enzymes thus shutting down the microbe’s metabolism
D) ex. peroxides, ozone (used on dialysis equipment), paracetic acid |
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Term
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Definition
A) “surface active” chemicals
B) generally work well against vegetative cells but not spores
C) work by disrupting cell membrane structure
D) ex. soaps, detergents and mouthwash |
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Term
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Definition
A) generally just slow growth but do not destroy the microbe
B) work by binding with sulfur in amino acids & altering protein’s shape thus inhibiting or eliminating function
C) ex. silver, mercury, zinc & copper
D) most are no longer used
1) copper is still used to control algae growth in water
2) copper, zinc, and mercury are used to control fungal growth in paint
3) silver nitrate is sometimes used to treat oral ulcers & silver ions are used in antimicrobial fabrics
a) silver nitrate was once required by law to be administered to the eyes of newborns to prevent ophthalmic gonorrhea
4) mercury (Mecurochrome) is still used today as antiseptic |
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Term
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Definition
A) work by denaturing proteins and inactivating nucleic acids
1) glutaraldehyde is used for cleaning lensed instruments and some respiratory
equipment
2) formaldehyde is used in vapor form to sterilize laboratories which have become contaminated
3) both are effective at sterilization |
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Term
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Definition
A) effective against all microbes, including endospores & viruses
B) works by reacting with proteins
C) useful in sterilizing fabrics (mattress,pillow) & implantable devices (pacemakers/artificial hips),as well as any heat or moisture sensitive items
D) objects need to be exposed for 3-12 hours for full sterilization
E) care must be used as the gas is toxic, explosive, and potentially carcinogenic
1) sterilization is followed by the object being treated with heated, forced air for 8-12 hours to dissipate any remaining ethylene oxide |
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Term
| Ultra high temp pasteurization |
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Definition
– 140-150 degrees for 1-3 seconds
(a) allows milk to be stored for long periods at room temp (ex. coffee creamers) |
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