what is flora?
population of microbes found on and in the body of healthy people
name all normal flora

normal microbiota

normal microbial flora

indigenous microbiota

Disruption of the normal microbiota results in infections caused by

Candida albicans, mycobacterium, clostridium difficile


Examples of Zoonaoses?
anthrax, salmonellosis, rabies, typhus
Type 1-Resident Flora=
inhabit body sites for extended periods of time; throughout life
Type 2-Transient flora=
only temporary
Zoonaoses are
Disease that are naturally spread from their usual animal hosts to humans.
5 ways a Zoonaoses can transmit disease

1.     Direct contact w/ animals or its waste

2.    Bloodsucking arthropods as vectors that transmit the microbe from animal to human

3.    Contaminationof food and water

4.    Indirect Contact with contaminated hides, fur, (wooler’s disease), feathers

5.     Consumption of animal meat or milk of infected animal products


Biological vector:
not only transmit pathogens, they also serve as hosts for the multiplication of pathogens during some stage of the pathogens life
Mechanical vector:
are not required as hosts by the pathogens they transmit; such vectors only passively carry pathogens to new hosts on their feet or other body parts.
Examples of Biological vectors

Biting arthropods; mosquitoes, ticks, lice, fleas, bloodsucking flies, mites, and bloodsucking bugs.


Examples of mechanical vectors?
housefly and cockroach
an infection must be trasmitted from either?
a reservior or portal of exit to another hosts portal of entry
what are 3 modes of trasmission?
contact trasmission, vehicle transmission, vector transmission
Type of Contact transmission are
direct, indirect or droplet
type of vehicle transmission is?
airborne, water-borne, food-borne, bodily fluid
types of vector transmission are?
biological transmission, mechanical transmission
what are the most important group of disease vectors
Biological vectors can
actively participate in pathogens life cycle. they can transmit pathoge
Examples of biological vectors:
Mosquitoes, Ticks, Lice, Fleas, Blood sucking flies, Blood sucking bugs, Mites
Mechanical vectors are what?
Animals are not necessary to the life cycle of the pathogen. Animals passively carry pathogen on their feet or body parts to drinking water, food, or on host skin.
Kirby Bauer tells us?

which drug is the drug of choice

which drug is the microbe most susceptible to

MIC test combined with Diffusion Susceptibility test is the?
eTEST determines?
susceptibility and MIC
The process of microorganisms in or on the body of other site
any adverse internal condition severe enough to  interfere with normal body functions
Successful invasion of the body by a pathogenic microorganism.
Endotoxin vs Exotoxin ARE?

Both are produced by Gram – bacteria, both can be fetal, both heat stable, but differ in their mechanism of release and composition


Endotoxins are?
are lipids released only when the cell dies b/c they are a part of the outer membrane. Can survive a hour of autoclaving at 121*C, produce fever, but only a weak immune response, so toxoid immunization is not a option.
Exotoxins are?

Also produced by Gram + bacteria.

Are proteins or peptides that are secreted, leaving the cell intact, toxicity is higher than Endotoxins, not stable above 60*C, produce a strong immune response and therefore toxoid immunization is possible.

Endotoxins are not secreted bu?
released only after the Gram – bacterial cell is damaged or lysed. Secreted from dead bacterial cells
4 examples of Exotoxins?





Examples of bacter that secrete Exotosxins?

Clostridium perfringens

Clostridium botulinum

Clostridium tetani

Staphylococcus aureus = exfoliate toxin

Streptococcus pyogenes

Vibrio cholera

Bordetella pertussis

E. coli: O157 = Shiga toxin


Iatrogenic is?
Diseases that are induced by modern medical procedures. “doctor induced”
congenital is
presented from birth… “born with”
5 stages of infection?

Portals of Entry = getting in

Attaching to the Host = staying in

Surviving Host Defenses = defeat host’s defenses

Causing the Disease = damage the host

Portals of Exit = getting out, transmitted to another host


5 stages of disease?

Incubation, prodromal period, illness, decline, convalenscence


Degerming is?

Removal of microbes from a surface by scrubbing, whether that surface is human skin or a table top), REMOVAL RATHER THAN KILLING OF MICROBES


Sterilization is?
is the Destruction (complete removal) of ALL microorganims and viruses in or on an object. This is done by steam, under pressure, incineration,or ethylene oxide gas.
Examples of sterilization
Ionizing radiation, incineration, autoclaving, and dry heat.
Endemic is?
a disease that occurs at a relatively stable frequency within a given are or population.
Epidemic is?
a disease that occurs at a greater than normal frequency for a given area or population.
Sporatic is?
a disease that occurs in only a few scattered cases within a given area or population during a given period of time.
Pandemic is?
the occurrence of an epidemic on more than one continent simultaneously.
Pathogen is?
any microorganisms that cause disease
True pathogen is?
PRIMARY PATHOGEN;are capable of causing disease in health person with normal immune defenses.
EXAMPLES of true pathogen?

Coronavirus causes acommon cold

Influenza virus causesa flu

Malarial protozoan causesa malaria

Opportunist pathogen is?

microorganism that may cause a disease under certain circumstances.


Opportunist pathogen can only cause disease when??

When host’s immune defenses are weakened or host is immunocompromised

When introduced into an unusual location

Opportunist pathogens May be members of the normal flora or common in the environment


examples of Opportunist pathogens?


E. coli

Pseudomonas= common in environment

Pasteurization is?
The process of heating milk or fruit juice to levels that kill any pathogenic microbes present
4 types of pasteurization?

historical pasteurization (batch)

flash pasteurization

ultrahigh-temp pasteurization

ultrahigh temp sterilization

Historical (batch) pasteurization you heat mild for?
30 minutes at 63*C
Flash pasteurization is when?

Milk flows through heated tubes that raise its temp to 72* for only 15 seconds. This treatment effectively destroys all pathogens.


Ultrahigh- temp pasteurization is when?
Milk is Heated to 134*c for only 1 second but some consumers claim it adversely affects the taste
Ultrahigh- temp sterilization does?

Heats milk to 140*c for 1-3 seconds.

Denatures proteins and destroys membranes

Sterilization of dairy products.


Brucella melitensis is target of?
prions can only be sterilized thru which method of sterilization?
How long is the boil H2O warning for?
10 minutes at 100*C
is it longer or shorter to boil than in Denver, CO?
It takes longer to boil water in Denver because Water boils at lower temperatures at higher elevations because there is less air pressure and steam escapes more quickly and pulls of excess heat.
Cross reistance is?

resistant to one antibicrobial agent

may confer resistance to similar drugs

especially when drugs have similar structures

Exampleas of cross resistant microbes?
Streptomycin, Neomycin, Gentamicin, Kanamycin
Multiple resistance means
“super bugsa resistant to 3 or more types of antiMicrobial agents
Multi-resistant strains of bacteria develop in?

Hospitals and nursing homes

Where the constant use of many kinds drugs eliminates sensitive cells and allow the growth of resistant strains

Multiple Resistance and Cross Resistance create?


examples of superbug strains?
Staphylococcus, Streptococcus, Enterococcus, Pseudomonas, Plasmodium
Synergist drugs are?
one drug that enhances the effects of a second drug
Examples of synergistic drugs?
pcn and streptomycin
Penicillin inhibits the formation of the____ and makes it easier for ____ to get inside the pathogen and interfere with protein synthesis.
cell wall; streptomycin
Antagonistic drugs?
interefere with each other
can something be partially sterile?
NO; either sterile or not sterile
what is ultra-high temp sterilization used for?

Dairy industry and other food processors use Ultrahigh-temperature sterilization to rid liquids of all living microbes.Can now be stored indefinitely at room temperature 134C or 273F;

Flash heating milk or other liquids to rid them of all living microbes;

Passing the liquid through superheated steam at 140*C for 1-3 sec, then cooling rapidly

does boiling for 10 minutes kill endospores, viruses, and cysts?
no b/c they can survive boiling for 10 minutes at sea level
boiling for 10 minutes rid of what?
both growing bacteria and enveloped viruses
Contagious is?
A communicable disease easily transmitted between hosts, either directly or indirectly.
example of a contagious disease?
FLUE, herpes, TB
Non-communicable are?

arise from outside the hosts or from normal microbiota. They are not spread from one host to another, and diseased patients are not a source of contamination.


examples of non-communicable disease?
tooth decay, acne, tetanus
ionizing radiation is?
electron beams, gamma rays, and x-rays
ionizing radiation destroys what?
IONIZING radiation is used to sterilize what?

Pharmaceuticals (drugs)

Disposable dental & medical supplies

Syringes, gloves, catheters

Tissues for grafts: bone, skin, heart valves

Mail to certain D.C. zip codes



NON-ionizing radiation is?
UV light
NON- ionizing radiation is used for?

Used for disinfection rather than sterilization

Kills microbes on the surface

Disinfecting air

Transparent fluids

Hospital rooms

Operating rooms

Food prep areas

Dental offices

Aseptic is?
an environment or procedure that is free of contamination by pathogens
Examples of aseptic?
Vegetables are available in aseptic packaging/Surgeon uses aseptic technique to avoid contaminating the surgical field
Antisepsis or Antiseptic is?

the use of chemical methods for eliminating or reducing microbes and viruses (particularly pathogens) on the skin or living tissue.

Antisepsis is a modification of disinfection.

Antiseptic are disinfectants whose strength is reduced to make them safe for living tissue.


Examples of antiseptics are?
frowth inhibiting chemicals such as alcohol or iodine
Which class of chemicals does Lysol belong to?


Lysol is a disinfectant

Lysol active ingredient is Orthophenylphenol

What is the appropriate range of percentages for using ETOH for a hand sanitizer?
Betadine belongs to which class of chemicals?

Betadine is a iodophore.

Iodine based products such as Betadine are Halogens.

What is a Iodophore?

Is an iodine-containing organic compound found in such antiseptics as betadine.

Combination of iodine and carrier which realeases iodine slowly.

Iodophores are less irritating that iodine tinctures.

What was once put in neonates eyes immediately following parturition? (Prevent eye infections)
1% silver nitrate
IN-USE test?

a.    More realistic method for determining the effectiveness of a disinfectant or antiseptic

b.    Swabs are taken from actual objects (operating room equipment) before & after application of disinfectant or antiseptic

c.    The swabs are inoculated onto nutrient agar plates & then incubated

d.    The plates are monitored for growth before & after the disinfectant was used


M.I.C = BACTERIOSTATIC=Minimum Inhibitory Concentration Test is?

is the smallest amount of the drug that will inhibit growth/reproduction of the pathogen.

§  MIC = attempts to quantify the smallest amount of drug that will inhibit a pathogen

 u  The MIC is determined by broth dilution test

u  After incubation, clear broth indicates that bacteria were either inhibited or killed

o   Determined by E-test


M.B.C = Minimum bactericidal concentration test = MBC test

O  MBC adetermines the dosage of the drug to be an effective bacteriocidal

  Samples are transferred to plates containing a Drug-free growth medium.

 ANY growth of bacterial colonies on a plate indicates that concentration of antimicrobial drug is… Only bacteriostatic.


What is a Beta Lactam Ring?
Functional unit of the beta lactum which is contained in Penicillin and cephalosporin and acts as NAM disruptors in the cell walls of bacteria.
what can inactivate the beta lactam ring?
which drugs have the beta lactam ring?
pcn and cephalosporin
Domagk discovered what?
first widely available antibiotic; sulfa drugs
Waksman did what
coined the term antibiotic
Alexander Fleming did what?

discovered that Penicillium chrysogenum, killed Staphylococcus aureus.

Fleming coined word Antibiotics


Sulfa drugs inhibit what?

– the metabolic pathway

– sulfa drugs are structural analogs of PABA

Paul Ehrlich (1854-1915) = “Magic Bullets”

          Produced Arsenic compound that killed Trypanosoma brucei = African sleeping sickness.  

– Produced Arsenic compound that killed Treponema pallidum = Syphilis Called it Salvarsan (salvation from syphilis)

what are the characteristics of the “ideal” antimicrobial?
1.  Inexpensive and fast-acting
2. Stable during storage
3. Control all microbial growth while being harmless to humans, animals, and object
Amphotericin B is?
is a fungicide that disrupts the cell (cytoplasmic) membrane. –  It attaches to ergosterol
Ergosterol is found in
fungal cell membranes causing lysis of fungal cells
Do we use Amphotericin B for minor infections?
yes we treat minor and serious infections with Amphotericin B
how do the “sulfa” drugs work?

Compete with PABA for enzymes active site

Are antimetabolites

When sulfa drugs bind to the pathogens enzyme the sulfa drug blocks the pathway for formation of Folic Acid

-Sulfa drugs bind irreversible to enzyme’s active site & block metabolic pathway

-Competitively inhibit the enzyme’s active site that PABA normally binds to

This stops the metabolic pathway & production of folic acid

No enzyme = No metabolic pathway (to manufacture the bacteria’s folic acid)

what are the 4 MAIN portal of entry and exit?


mucous membranes


parenteral route

what does a portal of entry mean?
Portal of entry are sites where pathogens enter the body. They are usually the same regions that support normal microbial flora.
Portal of entry with skin is?
insect bites, fungi enter thru openings, cuts, nicks, etc…
Mucous membrane portal of entry means?
Resp. tract., G.I tract, urogenital tract.
what is a placenta portal of entry?
usually an effective barrier against microbes in the maternal circulation, but some microbes cross the placenta.
what is a parenteral route portal of entry?
not a true portal of entry but a means by which portals can be circumvented (nail, thorn, needle, bites, stab wounds, surgery)
What are some examples of specific portal of entries?

– Inoculate influenza virus in nose and person gets flu but if the virus contacts only the skin, no infection results.

Contact with fungi in cracks in toe webs results in athlete’s foot infection But inhaling the fungal spores will not cause athlete’s foot

The study of the patterns, the occurrence, the spread of a disease in a population.

Manner in which disease develops

§  The structural and functional changes brought about by the disease

§  The final effects on the body


Can an opportunistic pathogen cause disease if introduced to an unusual site in the body?
Yes. If a member of the normal microbiota in one site is introduced into a site it normally does not inhabit, it may become an opportunist pathogen
How do we acquire our “normal flora”?

    As we development in the womb, it is free of microbes (axenic)

    Microbiota: begins to develop during the birthing process:

    When amniotic membrane is ruptured:

    Passage through the birth canal microorganisms enter mouth and nose;  First breath, First meal, Microbes from parents and hospital staff all contributes to normal microbiota.


A major source of infection in the world is what?


awatera fecal oral
is the number of new cases of a disease in a given area or population during a given period of time
is the total number of cases, both new and already existing, in a given area or population during a period of time. a cumulative number.
6 Exo-enzymes= extracellular enzymes

Hyaluronidase=bacteria go deeper into tissue

Collagenase=bacteria go deeper into tissue

Coagulase== coagulates blood proteins, bacteria hide

Kinases=breaks clot and releases bacteria

Mucinasedigest mucus= bacteria go deeper in tissue

Keratinase=digest keratin, bacteria go deeper in tissue


What is a fomite?
Inanimate objects involved in the indirect contact transmission of pathogens. A pathogen is spread from one host to another host by way of a fomite.
what are some examples of fomites?

Contaminated needles

u  Toothbrushes

u  Paper tissues

u  Toys

u  Money

u  Bed sheets

u  Medical equipment

u  Doorknobs

u  Telephones

u  Faucet handles

u  Paper cups

u  Towels

what are Koch’s postulates?
experimental epidemiology
what is the major drawback of Koch’s postulates?
Koch cannot be applied to every infectious disease to identify its causative pathogen.
What methods do we use to sterilize space-craft?
Ethylene Oxide
Which microbes can pass thru the placenta?

Placenta forms an effective barrier to most pathogens but in 2% of pregnancies pathogens cross the placenta and cause abortion, birth defects, or premature birth.

STORCH =syphillis, toxoplasmosis, other, rubella, cytomegalovirus, herpes

Other= (Hepatitis B, HIV, chlamydia (Listeria moncytogenes, Parvovirus)

All signs and symptoms of Lipid A intoxication?

Lipid A is an endotoxin that stimulates the body to release chemicals that cause; 

*Inflammation, diarrhea, hemorrhaging, shock, and blood coagulation. Lipid A can cause fatal endotoxic shock and can be fatal in high doses.

What are the methods of preserving food (stasis)?
Refrigeration is bacteriostatic for most microbes. It inhibits bacterial growth, but normal bacterial growth and metabolism can resume when optimal temperatures are restored. Freezing & drying are also methods
Can Beta-Lactam drugs be used to treat fungal infections?

No they treat bacterial infections!

Beta-lactam antibiotics have an effect on bacterial cell walls





What is the most limited group of antimicrobials we have?


          Why? Anything effective against the virus is toxic to the host as wellAntiviral medications frequently block unique enzymes to prevent production of new virus

Does UV light penetrate tissues (materials) more than gamma radiation?
Less effectively than Gamma rays
what is filtration used for?

A sterilizing agent; Sterilization of air and heat-sensitive ophthalmic and enzymatic solutions, vaccines, and antibiotics

Features with filtration:

o   Nitrocellulose or plastic membrane filters

o   Sterilization of heat-sensitive materials

o   Use of HEPA filters to filter air

o   Ability of some filters to trap viruses and proteins

What radiation do we use to clean the outside of our fruit?
Gamma Rays are used
What are the most difficult microorganisms to kill?


1.Bacterial endosproes:Endospores of Bacillus and Clostridium are the most resistant life forms
2.Species of Mycobacterium :cell walls have a waxy coat that prevents:
The entrance of water based chemical& Dehydration
3.Cysts of protozoa:Protozoal cysts wall prevents entry of Most disinfectants, 
Protects protozoa against drying & Shields protozoa against heat, and radiation


T/F Abx are produced by bacteria and fungi?


What is a toxoid?

Toxoids are toxinsthat have been treated with: Heat, Formaldehyde & Chlorineto to make them nontoxic

Toxoids consist of?
A purified fragment of the bacterial Toxins (Exotoxin’s) antigen. Toxoids stimulate Antibody production (antitoxins) for protection against toxinoses (diseases) Such as Diphtheria, Pertussis and Tetanus.  
what is a toxoid used for?
Categories: Microbiology