Micro - Unit 4

chronic carriers

carriers that are individuals who shelter the infectious agent for a long period after recovery because of the latency of the infectious agent. ex. TB, typhoid fever

convelescent carriers

carriers that are recuperating patients without symptoms; they continue to shed viable microbes and convey the infection to others ex. hep a

passive carriers

carriers that are usually medical and dental personnel who must constantly handle patient materials that are heavily contaminated with patient secretions and blood risk picking up pathogens mechanically and accidentally transferring them to other patients ex. various hai's

incubating carriers

carriers that spread the infectious agent during the incubation period ex. infectious mono

asymptomatic carriers

carries that are infected but show no symptoms of disease ex. gonorrhea, genital herpes with no lesions, HPV

necrosis

cell & tissue death caused from accumlated damage

phagocytes

cells that ordinarily engulf and destroy pathogens by means of enzymes and antimicrobial chemicals.

antiseptics

chemical agents that are applied directly to exposed body surfaces (skin & mucous membranes), wounds, and surgical incisions to destroy or inhibit vegetative pathogens. Ex. clean before surgical incision w/ iodine, ordinary hand washing with a germicidal soap.

bactericide

chemical that destroys bacteria except for those in the endospore stage. It may or may not be effective on other microbial groups. includes: fungicide, virucide, sporicide)

fungistatic

chemicals that inhibit fungal growth

septicemia

clinical term for blood infections, refers to a general state in which microorganisms are multiplying in the blood and are present in large numbers.

Cytotoxins

damage cell membranes or interfere with metabolsim ex. Streptolysin and other hemolysins

leukopenia

decrease in the level of white blood cells

epidemic

disease increases beyond what is expected for that population ex. STD's such as chlamydia & gonorrhea

reportable diseases

diseases that must be reported to authorities ex. anthrax, pertussis, rabies, syphillis, TB

synthetic drugs

drugs produced entirely by chemical reactions

semisynthetic drugs

drugs that are chemically modified in the laboratory after being isolated from natural sources.

Fecal transplants

Used to treat recurrent Clostridium difficile infection and ulcerative colitis

toxin

a specific chemical product of microbes that is poisonous to other organisms. Named according to its specific target of actions:

latency

after the initial symptoms in certain chronic infectious diseases, the infectious agent retreats into a dormant state

Toxemia

agent remains localized but toxins are spread throughout the body

bacteristatic

agents that prevent the growth of bacteria on tissues or on objects in the environment

allergy

Some drugs can cause an _________, a reaction that occurs because the drug stimulates the immune system.

High level, intermediate level, low level

Three Levels of Chemical Decontaminants

antimicrobials

all-inclusive term for any antimicrobial drug, regardless of its origin

pencillinase

an enzyme that hydrolyzes penicillin and is found in penicillin-resistant strains of bacteria AKA beta-lactamase

leukocytosis

an increase in the level of white blood cells

carrier

an individual who inconspicuously shelters a pathogen and spreads it to others without any notice.

noncommunicable

an infectious disease does not arise through transmission of the infectious agent from host to host. They are acquired through some other special circumstance. ex. fungal spores, tetanus

endemic

an infectious disease the exhibits a relatively steady frequency over a long time period in a particular geographic locale. ex. lyme disease

sign

any *objective* evidence of disease as noted by an observer --are more precise

symptom

any *subjective* evidence of disease as sensed by the patient.

Chemotherapeutic drug

any chemical used in the treatment, relief or prophylaxis of a disease

asepsis

any practice that prevents the entry of infectious agents into sterile tissues and thus prevents infection.

virucide

bactericide known to inactivate viruses, especially on living tissue.

Prodromal Stage

earliest notable symptoms appear (lasts 1-2 days)

pandemic

epidemic spreads across continents ex. AIDS & influenza

common source

exposure to single source infection over a period of time ex. contaminated water plant or a single restaurant worker that is a carrier of hep a and doesn't practice good hygiene

index case

first documented case

Transient flora

flora that clings to surface but does not grow there; drastically influenced by hygiene

Resident flora

flora that inhabits deeper parts of epidermis and in glands and follicles --is more stable --less influenced by hygiene --/Staphylococcus sp/. and /Candida albicans/ (fungus)

universal precautions

guidelines that are based on the assumption that all patients could harbor infectious agents and so must be treated with the same degree of care.

moist heat

heat that occurs in the form of hot water, boiling water, or steam (vaporized water). In practice, the temp this heat usually ranges from 60C to 135 C. -Shorter exposure times to achieve effectiveness. --many cellular structures are damaged by this heat --its most microbial effect is the coagulation and denaturation of proteins, which quickly & permanently halts cellular metabolism. --Methods: boiling water, pasteurization, steam under pressure

dry heat

heat that refers to hot air (such as in an oven) or an open flame. In practice, the temp of this heat ranges from 160c to several thousand degrees C --this heat dehydrates the cell, removing the water necessary for metabolic reactions --denatures proteins --actually increases the stability of some protein conformations, necessitating the use of higher temps when this is employed as a method of microbial control. --at very high temps, it oxidizes cells, burning them to ashes. --methods: incineration, hot air oven

semicritical

how devices should be handled that come into contact with mucosal membranes. Ex. endoscopy tube Must receive at least high-level disinfection and preferable should be sterilized.

noncritical

how items should be handles that do not touch the patient or are only expected to touch intact skin. ex. bp cuff, crutches. They require only low-level disinfection unless they become contaminated with blood or body fluids.

contagious

if an infectious agent is highly communicable, especially through direct contact

vector transmission

includes: mechanical vector & biological vector

Period of Invasion

multiplies at high levels; exhibits greatest virulence

Asymptomatic (subclinical)

no signs or symptoms

Transmitter

individual or object from which the infection is acquired

zoonosis

infection indigenous to animals but naturally transmissible to humans

systemic infection

infection spreads to several sites and tissue fluids (usually via the bloodstream), but may travel by other means such as nerves (rabies) and cerebralspinal fluid (meningitis) ex. mumps, rubella, chicken pox, AIDS, syphilis

polymicrobial

infections in which the disease symptoms are influenced by more than one colonizer.

point-source

infectious agent from a single source and all of its "victims" were exposed to it from that source. ex. food poisoning

propagated epidemic

infectious agent is communicable from person to person and is therefore sustained over time in a population. ex. influenza

focal infection

infectious agent spreads from a local site and is carried to other tissues ex. TB, streptococcal pharyngitis

healthcare-associated (nosocomial)

infectious diseases that are acquired or develop during a hospital or health care facility stay include UTI's, respiratory tact infections, surgical incision infection

Infectious dose (ID)

is the minimum number of microbes present for an infection to proceed The smaller the ID, the greater the virulence of the microbe

localized infection

microbes enter the body, remain confined to a specific tissue ex. boils, warts, fungal skin infection

Superinfection

microbes that were once small in number overgrow when normal resident biota are destroyed by broad-spectrum antimicrobials

drug resistance

one unfortunate outcome of the use of antimicrobials. It is an adaptive response in which microorganisms begin to tolerate an amount of drug that would ordinarily be inhibitory. --Due to the genetic versatility and adaptability of microbial populations --Can be intrinsic as well as acquired

acids & alkali's

other microbial agent --Low or high pH can destroy or inhibit microbial cells --Limited application due to corrosive, caustic and hazardous nature --Acids-food preservatives

Dyes

other microbial gent that has limited use due to narrow spectrum of activity --Aniline dyes-crystal violet and malachite green-effective against gram positive bacteria and some fungi --Yellow acridine dyes-acriflavine and proflavine-antisepsis and wound treatment in vet clinics

opportunistic pathogen

pathogen causing disease when the host's defenses are compromised or when the pathogens become established in a part of the body that is not natural to them.

portal of exit

pathogens depart by a specific avenue. Most cases the pathogen is shed or released from the body through secretion, excretion, discharge, or sloughed tissue.

true pathogens

pathogens that are capable of causing disease in healthy persons with normal immune defenses. ex: cold, flu, protozoa

infection control officer

person that implements practices and tracks potential outbreaks in hospitals

disinfection

physical process or a chemical agent to destroy vegetative pathogens but not bacterial endospores. Removes harmful products of microorganisms (toxins) from material. Normally used on inanimate objects Common uses: boiling food utensils, applying 5% bleach solution to an examining table, immersing thermometers in an iodine solution between uses. ex. Bleach, iodine, heat (boiling)

sterilization

process that destroys or removes all viable microorganisms (including viruses). Generally reserved for inanimate objects Common uses: surgical instruments, syringes, commercially packaged food Ex. heat (autoclave), sterilants (chemical agents capable of destroying endospores)

virulence factors

properties that enable a microbe to invade and infect a host.

antagonism

relationship in which microorganisms compete for survival in a common environment by taking actions that inhibit or destroy another organism.

exotoxin

released by living bacterial cells into infected tissues. with a strong specificity for a target cell and extremely powerful, sometimes deadly, effects

horizontal

route or pattern of disease transmission when the disease is spread through a population from one infected individual to another includes direct, indirect & vector transmission

Koch's postulates

series of proofs that establish a principal criteria of etiologic studies

Persisters

slowing or stopping of metabolism so that the microbe can't be harmed by the antibiotic (one reason biofilm bacteria are less susceptible to antibiotics than free-living bacteria are)

prokaryotic

small cells, lacing special structures such as a nucleus and organelles. All of these are microorganisms.

epidemiology

study of disease in populations involves the study of the frequency and distribution of disease & other health-related factors.

Slime (or capsule )

substance on surface making phagocytosis difficult (/Streptococcus pneumoniae, Salmonella typi/)

antibiotics

substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms.

leukocidins

substances that are toxic to white blood cells (/Streptococcus and Staphylococcus/)

Convalescent Period

symptoms decline, followed by recovery

thermal death point (TDP)

the *lowest* temperature required to kill all microbes in a sample in 10 minutes

thermal death time (TDT)

the *shortest* length of time required to kill all test microbes at a specific temperature. --been experimentally determined for the microbial species that are common or important contaminants in various heat-treated materials

physical & chemical

the 2 broad categories of controlling microorganisms

Urgent threat

the antibiotic resistance threat level of: --Clostridium difficile --Carbapenem-resistant Enterobacteriaceae --Drug-resistant Neisseria gonorrhoeae

Serious threat

the antibiotic resistance threat level of: --Multidrug-resistant Acinetobacter --Drug-resistant Campylobacter --Fluconazole-resistant Candida --Many more

concerning threat

the antibiotic resistance threat level of: --Vancomycin-resistant Staphylococcus aureus --Erythromycin-resistant Group A Streptococcus --Clindamycin-resistant Group B Streptococcus

etiologic agent

the causative agent of a disease

etiology

the cause, set of causes, or manner of causation of a disease or condition

peptidoglycan

the cell wall is a rigid structure found in bacteria that is made of _________________ and lies just outside the cell membrane.

cellular synthesis

the cellular target of agents that can interrupt the synthesis of proteins via the ribosomes, inhibiting proteins needed for growth and metabolism and preventing multiplication. Agents can change geteic codes (mutations) ex. formaldehyde, radiation, ethylene oxide

lyophilization

the combination of freezing & drying --a common method of *preserving* microorganisms and other cells in a viable state for many years.

infectious disease

the disruption of a tissue or organ caused by microbes or their products

inflammation

the earliest symptoms of disease result from the activation of the body defense process. Includes cells and chemicals that response nonspecifically to disruptions in the tissue commpn symptoms: fever, pain, soreness & swelling. Signs: edema, granulomas, abscesses, swollen lymph nodes.

sepsis

the growth of microorganisms in the blood and other tissues.

sequelae

the long-term or permanent damage to tissues or organs left by some diseases.

mortality rate

the measure of the total number of deaths in a population due to a certain disease

incidence

the number of new cases of a disease over a certain time period. this statistic also called the case, or morbidity, rate indicates both the rate and the risk of infection.

adhesion

the process by which microbes gain a more stable foothold on host tissues. Because this is dependent on binding between specific molecules on both the host & pathogen, a particular pathogen is limited to only those cells (and organisms) to which it can bind. Bacterial, fingal, and protozoal pathogens attach most often by mechanisms such as fimbriae (pili), surface proteins, and adhesive slimes or capsules; viruses attach by means of specialized receptors. --Firm attachment to host tissues is almost always a prerequisite for causing disease since the body has so many mechanisms for flushing microbes and foreign materials from its tissues.

therapeutic index (TI)

the ration of the dose of the drug that is toxic to humans as compared to its minimum effective (therapeutic) dose. --The closer these two figures are (the smaller the ratio), the greater is the potential for toxic drug reactions. --Drugs (with similar MICs) with the highest TI usually have the widest safety margin

virulence

the relative severity of the disease cause by a particular microorganism to invade and harm host cells

vertical

the route or pattern of disease transmission from parent to offspring via ovum, sperm, placenta, or milk.

endogenous

the source of the infection agent originating from a source already existing on or in the body (normal biota or a previously silent infection) (i.e., Candidiasis—yeast infection)

exogenous

the source of the infectious agent originating from a source outside the body (the environment or another person or animal) ie: the common cold

human microbiome

the sum total of all microbes found on and in a normal human, it is critically important to the health and functioning of its host organisms.

prevalence

the total number of existing cases of a disease with respect to the entire population

secondary

the type of infection that is caused by different microbe which complicates the primary infection (usually due to compromised immune system) ex. influenza complicated by pneumonia, common cold complicated by bacterial otitis media

indirect transmission

the type of transmission that must pass from an uninfected host to an intermediate conveyor and from there to another host. Infected individuals contaminate objects, food, or air through their activities Fomite: inanimate object (doorknob, phone) Vehicle - natural, nonliving material air, water, soil, food **oral-fecal route - vehicle or fomite

antimicrobial chemotherapy

the use of chemotherapeutic drugs to control infection

Incubation Period

time of initial contact with infectious agent to the appearance of symptoms (usually 2-30 days)

portal of entry

to initiate an infection, a microbe enters the tissues of the body by this route.. Usually skin or a mucous membrane.

Endotoxin

toxin released from outer membrane of gram-negative bacteria (usually when damaged or destroyed) ex. Lipopolyaccharide (LPS)

enterotoxin

toxin that acts on the intestine ex. Cholera and shiga toxins

neurotoxin

toxin that acts on the nervous system ex. Tetanospasm and anthrax toxin

nephrotoxins

toxins that damage the kidneys

hemotoxin

toxins that lyse red blood cells

communicable

type of disease when an infected host can transmit the infectious agent to another host and establish infection in that host.

broad-spectrum

type of spectrum of drugs that are effective against more than one group of bacteria ex. tetracyclines

narrow-spectrum

type of spectrum of drugs that generally target a specific group of bacteria ex. polymyxin & penicillins

direct transmission

type of transmission that involves physical contact between infected person and that of the new infectee ex. touching, kissing, etc. --droplet contact, sneezing or coughing --parenteral transmission - via intentional or unintentional injection into deeper tissues (needles, knives, branches, broken glass, etc)

biological vector

type of vector transmission that insect injects microbes into host; part of microbe life cycle completed in insect

mechanical vector

type of vector transmission that insects carries microbes to host on its body parts

antiphagocytic factors

type of virulence factor used by some pathogens to avoid phagocytes. Helps microorganisms to circumvent some part of the phagocytic process.

prophylaxis

use of a drug to prevent imminent infection of a person at risk

microbistatic

used to control microorganisms in the body (antiseptics and drugs) often have this effect because many microbicidal compounds can be highly toxic to human cells.

Chlorine

what chemical is a halogen --Target microbes: can kill endospores (slowly); all other microbes. Kills bacteria, endospores, fungi, and viruses --Possible Sterilant --Liquid and gas forms --Mode of action: combine with water in solution and release hypochlorous acid (HOCI) which denatures enzymes and suspends metabolic reactions --Used to disinfect drinking water, sewage treatment --Hypochorites used in health care to treat wounds, disinfect bedding and instruments --Used to sanitize restaurant equipment --Used in pools and spas --Disadvantages: Becomes less effective if exposed to light, alkaline pH, excess organic matter

selectively toxic

what drugs should be so they kill or inhibit microbial cells without simultaneously damaging host tissues. --this concept is central to antibiotic tx, and the best drugs in current use are those that block the actions or synthesis of molecules in microorganisms but not in vertebrate cells ex.. Penicillins are excellent in damages thing cell wall of bacteria but have a low toxicity to human cells

syndrome

when a disease can be identified or defined by a certain complex of signs & symptoms.

sporadic

when a disease has only occasional cases and are reported at irregular intervals in random locales

microbistasis

when microbes are temporarily prevented from multiplying but are not killed outright

bacteremia

when small numbers of bacteria are found in the blood

viremia

when small numbers of viruses are found in the blood

Kirby-Bauer method (The Disk Diffusion Method)

which drug susceptibility testing technique is an agar diffusion test that provides useful data on antimicrobial susceptibility. --In this test, the surface of a plate of special medium is spread with the test bacterium, and small discs containing a premeasured amount of antimicrobial drugs are placed on the agar surface. --After incubation, the clear areas called *zones of inhibition* appear on the agar as round disks where the drugs inhibit the bacteria. --Important to realize the results obtained in vitro (in the lab) often differ from those obtained in vivo (in a living organism) --metabolic processes in a living organism may inactivate or inhibit a drug. --this profile of antimicrobial sensitivity is called an *antibiogram* --this test is less effective for bacteria that are anaerobic, highly gastidious, or slow growing (Mycobacterium).

E Test

which drug susceptibility testing technique is an alternate diffusion system that provides additional information on drug effectiveness? --more sensitive and quantitative results can be obtained with tube dilution tests. -- test that uses a strip to produce the zone of inhibition. Advantage of this test is that the strip contains a gradient of drug calibrated in micrograms; This way the minimum inhibitory concentration (MIC) can be measured by observing the mark on the strip that corresponds to the edge of the zone of inhibition

Quinine

-historically used to treat malaria; synthesized quinolones, chloroquine and primaquine now used

DRACO

"double-stranded RNA-activated caspase oligomerizer" --Breakthrough antiviral treatment currently being tested --Will hopefully result in a broad-spectrum antiviral

The Dilution Method

A constant quantity of microbial inoculum is introduced into a series of broth cultures containing decreasing concentrations of a drug. After incubation, the tubes are examined and the lowest concentration of the drug that prevents visible growth (indicated by turbidity) is noted. --Advantage to using this method over the disk method: Samples from tubes that show no growth can be used to inoculate broth that contains no drug to see if the drug was bactericidal or bacteriostatic.

ad

A virus is an acellular infectious agent composed of: (select 2 that apply) a) protein coat b) lipid-rich core c)ribosomes d) RNA or DNA core

penicillinase

An enzyme that hydrolyzes penicillin and is found in penicillin-resistant strains of bacteria

alcohol

An example of an agent that lowers the surface tension of cells is phenol chlorine alcohol formalin

Narrow-Spectrum (limited spectrum)

Antimicrobials effective against a limited array of microbial types - for example, a drug effective mainly against gram-positive bacteria

Broad-Spectrum (extended spectrum)

Antimicrobials effective against a wide variety of microbial types-for example, a drug effective against both gram-positive and gram-negative bacteria.

biofilms

Bacteria in __________ behave differently than when they are free-living --Often unaffected by antimicrobials --Antibiotics often cannot penetrate the sticky extracellular material surrounding them --Bacteria in these express a different phenotype and have different antibiotic susceptibility profiles than free-living bacteria

bc

Biofilm intections are found in/on which of the following? (select all that apply) a) between the toes b) urinary catheter c) middle ear d) conjuctiva

Steam under pressure

-- moist heat sterilization --Autoclaves - steam under pressure --Provide high temp and high pressure (Pressure: 1 atm, temp.: 121 C) --Steam should contact all surfaces --Holding time varies between 10-40 minutes; average 20 (bulkiness of load and fullness of chamber affect holding time) --Used for sterilization of: Culture media Equipment Biological waste

High Level Germicides

--Kill endospores --Can be sterilants --Used for catheters, heart-lung equipment, implants

Intermediate Level Germicides

--Kill fungal but not bacterial spores and resistant pathogens like the tubercle bacillus and viruses --Used to disinfect items that come into intimate contact with mucous membranes but are non invasive (respiratory equipment, thermometers)

boiling

--Moist heat Disinfection --Nonpressurized steam --Boiling (100C) for 10 min kills vegetative cells of bacteria, viruses, and fungi --Hepatitis virus can survive up to 30 min of boiling; some bacterial spores can survive more than 20 h. --Tyndalization - boiling the medium for 60 min repeatedly for 3 day

Desiccation

--NOT A METHOD OF STERILIZATION OR DISINFECTION --Vegetative cells exposed to room air eventually become dehydrated --In the absence of water microbes cannot grow but can survive --Bacterial spores can survive for centuries --Survival depends on microbial type and organism's environment (embedded in mucus - better survival) --Mycobacterium tuberculosis - long survival --Neisseria gonorrhoeae - dies after a few hours of air drying

Osmotic Pressure

--NOT a sterilizing technique; prevents multiplication of microbes --High concentration of salt causes water to leave the cell --Used in preservation of food (high sugar concentration - fruit preserve)

Low Level Disinfection

--Only eliminate vegetative cells and some viruses --Used to clean materials that come into contact with skin, but not mucous membranes (electrodes, furniture, straps, etc.)

Exoenzymes

--Secreted by many pathogenic bacteria, fungi, protozoa and worms --Damage tissue or dissolve host's defense barriers --*Mucinase*-digests protective coating on mucous membranes (amoebic dysentery) --*Hyaluronidase*-digest hyaluronic acid which holds animal cells together (staphylococci, clostridia, streptococci, pneumococci) --*Coagulase*-causes blood clotting (staphylococci) --*Kinases*-dissolve clots (streptococci, staphylococci)

Alcohol

--Target Microbes: Most bacteria, viruses, fungi --Ethanol or isopropanol 60% - 95% --Kills vegetative cells of bacteria and fungi (not spores and nonenveloped viruses) --Mode of action: dissolves membrane lipids, disrupts membrane integrity --Nonirritating and inexpensive --Used as skin degerming agent (70-95% solutions) --Disadvantages -Fast evaporation rate decreases effectiveness -Vapors can affect the nervous system

Detergents (soaps)

--Target Microbes: Some bacteria, viruses, fungi --Chemicals with surface action -Detergents are polar molecules - surfactants -Decrease the surface tension among molecules and water -Soaps and Detergents are not antiseptics - they break the oily film on the surface of skin --They have microbicidal power when mixed with quaternery ammonium compounds (quats) --Effective against some viruses, algae, fungi and gram positive bacteria --Rate only for low level disinfection in clinical setting --Mode of action: Disrupts cell membrane causing it to loose selective permeability leading to cell death -Used to clean restaurant utensils, dairy equipment, surfaces, restrooms --Disadvantages: -Reduced activity in presence of organic matter -Ineffective against tuberculosis bacterium, hepatitis virus, Pseudomonas and endospores

Heavy Metal Compounds

--Target Microbes: Some bacteria, viruses, fungi --Only mercury and silver have germicidal significance --Effective against some bacteria, viruses and fungi --Mechanism of action: ions combine with sulfhydril groups - protein denaturation --Organic mercury tinctures are fairly effective antiseptics, opthalamic solutions --Silver nitrate used for topical germicides and ointments --Disadvantages: -Microbes can become resistant -Not effective against endospores -Can be toxic -May cause allergic reactions

Phenol (Carbolic Acid)

--Target Microbes: Some bacteria, viruses, fungi --Phenolics (derivatives of phenol) --Used first time by Lister - carbolic acid --Kills some bacteria, viruses and fungi --Mechanism of action: damages the plasma membrane, enzyme inactivation --Advantage: active even in the presence of organic compounds -Hexachlorophene (bisphenol) used in antimicrobial soaps --Disadvantages -Toxicity of many phenolics make them dangerous to use as antiseptics --Now used only in limited cases like drains, cesspools and animal quarters

Chlorhexidine

--Target Microbes: most bacteria, viruses, fungi --Popular due to low toxicity and rapid action --Mode of action: targets bacterial membranes causing loss of selective permeability; denatures proteins --Used in hand scrubs, skin prep for surgery, obstetric antiseptic --Disadvantage: effect on viruses and fungi variable

Gaseous sterilants disinfectants

--Target microbes: ethylene oxide kills endospores; other gases less effective --Can be sterilant Ethylene oxide Can kill endospores --Mode of action: blocks DNA replication and enzyme action --Used to disinfect plastic and delicate instruments; can be used to sterilize syringes, surgical supplies and medical devices --Disadvantages: Explosive Can damage lungs, eyes, mucous membens Carcinogen

aldehydes

--Target microbes: kill endospores and all other microbes --Can be a Sterilant --High level disinfectant --Include formaldehyde, glutaraldehyde --Includes: -Glutaraldehyde Mode of action: disrupts proteins Rapid, broad spectrum Used to sterilize respiratory equipment, dialysis machines, dental insturments --Disadvantage: unstable -Formaldehyde-gas that combines with water to form formalin Mode of action: attaches to nucleic acids and amino acid functional groups Slower in action Used to disinfect surgical instruments --Disadvantages: toxic and irritating to skin and mucous membranes

hydrogen peroxide

--Target microbes: kills endospores and all other microbes --Can be a sterilant --3% solution used as an antiseptic -Skin and wound cleansing -Mouthwash -Contact lens --35% used in low temp sterilizing cabinets for delicate instruments --Can be used to treat infections caused by anaerobic bacteria --Disadvantages: Sporicidal only in high concentrations

Heat

--Temps exceeding maximum growth temp are usually microbicidial while those below the minimum growth temp are microbistatic --Bacterial endospores have greatest resistance to heat; usually require temps above boiling to destroy --Vegetative states of bacteria and fungi are least resistant to heat --Viruses highly resistant to heat --Thermal Death Time (TDT): shortest length of time required to kill all the microbes at a specified temp --Thermal Death Point (TDP): lowest temp required to kill all microbes in a sample in 10 minutes --application Moist or Dry

Pasteurization

--moist heat disinfection --Technique applied to liquids to kill the agents of infection while retaining the liquids flavor and food value --Batch Method: (original method) 63 C for 30 min --Flash Method (preferred method)- high temperature short-time pasteurization: 72 C for 15 sec. or --Ultra-high-temperature (UTH) treatment - Exposure to 134 C for 3 sec. then rapidly cooled)—sterile milk (shelf life of 3 months)

microbial death

--the permanent loss of reproductive capability under optimum growth conditions --Variation in cells of a culture in susceptibility to a microbicidal agent --Death of a whole population is not instantaneous; begins when threshold of microbicidal agent is met and continues in logarithmic manner --Several factors affect the action of antimicrobial agents

decontamination (sanitization)

Cleansing technique that mechanically removes microorganisms as well as other debris to reduce contamination to safe levels. Important to restaurants, dairies, breweries, and other commercial entities that handle large numbers of soiled utensils/ containers. Common uses: cooking utensils, dishes, bottles for reuse Ex. Soaps, detergents, commercial dishwashers

d

Microbe(s) that is/are the targets of pasteurization include a. Costridium botulinum b. Mycobacterium species c. Salmonella species d. both b & c

endospores

Microbial control methods that kill _________ are able to sterilize. viruses the tubercle bacillus endospores cysts

bacteria

Drugs designed for __________ are not effective against fungal infections

pathogenicity

a broad concept that describes an organism's potential to cause disease and is used to divide pathogenic microbes into one of two groups.

eukaryotic

a cell that differs from a prokaryotic cell cheifly by having a nuclear membrane (well defined nucleus), membrane-bound subcelluar organelles, and mitotic cell division.

pathogen

a microbe whose relationship with its host is parasitic and results in infection and disease

Chemical Agents of Microbial Control

Chemical Agents of Microbial Control --Antimicrobial chemicals occur in liquid, gas or solid state --Gases usually dissolved in water, alcohol, or both ---Dissolved in water: aqueous solution ---Dissolved in alcohol: tinctures --Can be disinfectants, antiseptics, sterilants, preservatives (prevent deterioration) Desirable qualities of a germicide: --Rapid action in low concentration --Soluble in water or alcohol with long term stability --Broad spectrum microbicidal action --Not harmful to human or animal tissue --Penetration of inanimate objects --Resistant to inactivation by organic matter --Non corrosive --Nonstaining --Sanitizing --Deodorizing properties --Affordable --Readily available

Antisepsis (degermation)

Reduces the number of microbes on the human skin. A form of decontamination but on living tissues. Involves scrubbing the skin (mechanical friction) or immersing it in chemicals (or broth) Ex. Alcohol, surgical hand scrub

iodine

Halogen --Target microbes: can kill endospores (slowly); all other microbes --Possible Sterilant --Exists as free iodine or Iodophors (tincture) --Mode of action: interferes with metabolic functions; interferes with disulfide bonds of proteins --Uses: -2% used as topical antiseptic -5% , 10% potassium iodine used to disinfect plastic and rubber instruments and cutting blades -Iodophore used to prepare skin for surgery, surgical scrubs, burn treatment and disinfectant --Disadvantages: Irritating to skin Toxic when absorbed

b

High temperatures __________ and low temperatures __________. a. sterlize. disinfect b. kill cells; inhibit growth c. denature proteins; burst cells d. speed up metabolism; slow down metabolism

critical

How medical devices that are expected to come into contact with sterile tissues are to be handled. ex. syringe needle or artificial hip.

Acute infection

Infection comes on rapidly with severe short lived effects ex. flu

Chronic infection

Infection that progresses and persists over a long period of time ex. HIV

Microbial antagonism

Normal biota are unlikely to be displaced by incoming microbes; limited number of attachment sites; chemical or physiological environment created by resident biota is hostile to other microbes

Prebiotics

Nutrients that encourage the growth of beneficial microbes

Radiation

Physical Control Mechanism --Ionizing radiation (gamma rays, X-rays) --*STERILIZATION * --Short wavelength, high energy --Sterilization of materials that are sensitive to heat and chemicals --Irradiation of food --Mechanism of action: ionization of water which forms hydroxyl radicals which react with DNA --Non-ionizing radiation (UV light) --DISINFECTION; Sterilization can be achieved, but difficult --Not as penetrating as ionizing radiation --UV light, germicidal light Mechanism of action: damage of DNA - formation of thymine dimmers --Sterilization of the air (hospital rooms, operating rooms, cafeteria) --Can be harmful to human eyes, skin

Cold

Physical Control Mechanism --NOT A METHOD OF DISINFECTION OR STERILIZATION --Effect depends on the microbial type --Ordinary refrigeration (0-7 C) - bacteriostatic effect --Psychotrophs grow slowly --Pathogenic bacteria will not grow --Rapid freezing - microbes become dormant --Lyophilization - frozen samples (bacterial cultures) dried in vacuum --Slow freezing - more harmful

Filtration

Physical Control Mechanism --Removal of microbes from air and liquids --Liquids passed through filter with openings large enough for fluid to pass, but too small for microbes to pass --Used to prepare liquids that cannot withstand heat—serum, blood products, vaccines, IV fluids, etc. --Decontamination of beer and milk Disadvantage: does not remove soluble molecules that can cause disease (toxins) --Removal of airborne contaminants using high efficiency particulate air filter (HEPA)

R factors

Plasmids, typically shared among bacteria by conjugation, that provide resistance to the effects of antibiotics.

Probiotics

Preparations of live microorganisms fed to animals and humans to improve intestinal biota

Reservoirs

Primary habitat in the natural world from which a pathogen originates May be living or nonliving

sterilization, disinfection, decontamination, antisepsis

The 4 methods of microbial control used *outside* the body are

quorum sensing

The ability of bacteria to regulate their gene expression in response to sensing bacterial density.

a

Sanitation is a process by which a: the microbial load on objects is reduced b. objects are made sterile with chemicals c. utensils are scrubbed d. skin is debrided

d

Select the correct sequence, from least to most resistant: a. Most, gram -negative bacteria, enveloped viruses, prions b. most gram-negative bacteria, staphylococcus, enveloped viruses c. most gram-negative bacteria, most gram-positive bacteria, prions d. enveloped viruses, protozoan, cysts, bacterial endospores e. enveloped viruses, most gram-negative bacteria, most gram-positive bacteria

mixed infection (polymicrobial infection)

Several agents establish theneselves simultaneously at the infection site ex. human bite infections, wound infections, gas gangrene.

cytoplasmic membrane

The cellular target for agents that physically bind to lipid layer of the cytoplasmic membrane, opening up the cytoplasmic membrane and allowing injurious chemicals to enter the cell and important ions to exit the cell. ex. detergents

cellular wall

The cellular target for chemical agents that can damage the cell wall by blocking its synthesis, or digesting the call wall. ex. chemicals, detergents, alcohol

proteins

The cellular target of agents that are capable of denaturing proteins (breaking of protein bonds, which results in breakdown of the protein structure) Agents may attach to the active site of a protein, preventing it from interacting with its chemical structure. ex. Moist heat, alcohol, phenolics

biofilm

The mixed communities of different kinds of bacteria and other microbes that are attached to a surface and to each other, forming a multilayer conglomerate of cells and intracellular material.

filtration

The most versatile method of sterilizing heat-sensitive liquids is: UV radiation exposure to ozone beta propiolactone filtration

b

The primary mode of action of nonionizing radiation is to a: produce superoxide ions b. make pyrimidine dimers c. denature proteins d. break disulfide bonds

cell wall

The rigid structure found in bacteria that is made of peptidoglycan and lies just outside the cell membrane.

fungal

The similarities between ____________ and human cells often mean that drugs toxic to the this type of cells are also capable of harming human tissues.

MIC

The smallest concentration (*highest dilution*) of drug that visibly inhibits growth; important in determining smallest effective dose of a drug

primary

The type of infection that is the initial infection.

penicillinase

What bacterial enzyme makes a cell wall inhibitor drug ineffective? Coagulase Cephalosporin Hyaluronidase Penicillinase

bd

Which of the following are NOT primary sites for action of antimicrobial drugs in bacteria? a) nucleic acids b) Golgi apparatus (bodies) c) cell membrane d) mitochondria e) cell wall f) ribosomes

sporicide

a bactericide capable of destroying bacterial endospores. This type of agent can also be a sterilant because it can destroy the most resistant of all microbes.

fungicide

a bactericide that can kill fungal spores, hyphae, and yeasts.