Exam #3 (PART 1) Flashcards
Define microbiota or normal flora.
Commensalistic or mutalistic bacteria and fungi that live in anatomical barriers (epithelial barriers:skin & mucous membrane) in human body
When do microbiota establish in our body?
- At birth: by exposure to mother’s normal microbiota.
2. Later on with exposure to food, water, and other humans.
Where can the microbiota be found?
Nose Mouth & Throat Skin Large Intestine Vagina Urethra
Why does P.acne causing acne occur during puberty and then disappear with time?
- Innate immunity attacks the bacteria as first, but then the body develops adaptive immunity (t helpher cells contain memory)
- Pimples are a result of inflammation and phagocytes → pus, they disappear with time because of the development of the adaptive immunity, Th cells contain memories.
Give one example of bacteria that are not found in vegetarians but do exist in non vegetarians.
Bacteroides spp
All the advantages that are provided by the normal flora to their host? (4)
- Prime the immune system: a low bacteria of cross anatomical barriers and stimulate the immune system
- Prevent pathogens from attaching
- Compete for nutrients with pathogens
- Produce toxic compounds that inhibit other microbes
What are probiotics and why are they important for our health?
Probiotics are organisms such as bacteria or yeast that are believed to improve health. They are available in supplements and foods. They help establish bacteria that may have been disrupted in our normal flora and could help one maintain a good immune system.
Pathogen
microorganism that is capable of causing disease
Pathogenicity
ability of a microbe to cause a disease
Opportunistic Pathogen
cause a disease in suppressed people or when introduced in an unusual location
Infection
the invasion of a host organism’s body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce
ex.HIV
Disease
A particular abnormal, pathological condition that affects part or all of an organism
ex. AIDs
Primary Infection
the initial infection of a host by a pathogen that has completed a resting or dormant period
Secondary Infection
follows primary infection; makes a person more susceptible to disease
Describe the course of an infectious disease including the following periods:
Incubation period
Period of illness
Convalescence
Incubation period- infection stage, exposure, adherece/attachment
Period of illness- disease stage- tissue damage, invasiveness, toxicity
Convalescence- body return to predisease state
Viremia
presence of viruses in blood
Bacteremia
presence of bacteria in the blood
Septicemia
when bacteria is multiplying in the blood
Toxemia
presence of toxins in the blood
List three ways by which bacteria may avoid phagocytosis?
1- preventing encounters with phagocytes,
2- avoiding recognition and attachment
3- surviving within phagocytes
What are superantigens , give one example , explain how they trigger a cytokine storm and why do they cause shock.
Super antigens are a class of antigens that cause non-specific activation of T-cells resulting in polyclonal T cell activation. Staph. aureus override the specificity of the helper T cell response causing toxic effects due to the massive release of cytokines by T helper cells which enters the blood stream
What is the difference between cytotoxic toxin and cytolytic toxin?
cytotoxic: quality of being toxic to cells
cytolytic: occurs when a cell bursts due to an imbalance that has caused excess water to move into the cell
Give three examples of cytolytic toxins.
leukocidins
α-toxin
phospholipase
List all the invasive enzymes that are associated with Staph.aureus
- coagulase
- catalase
- hyaluronidase
- fibrinolysin
- lipase
- nuclease
- penicillinase
List all the virulence factors which allow S.aureus to hide/destroy from the immune system.
- clumping factor
- Fibronectin-binding protein
- protein A
- alpha toxin
- leukocidin
- enterotoxin
- toxic shock syndrome toxin-1
The _______produced by Clostridium botulinum and Clostridium tetani are examples of virulence factors.
neurotoxins
The _____ produced by Clostridium perfringens and Streptococcus pyogenes are examples of virulence factors
necrotizing enzymes
_________ are exoenzymes that cause clot formation.
coagulases
_____ are exoenzymes that dissolve clots.
Kinases
______ are produced by Clostridium difficle, Salmonella spp.,
enterotoxins
______ is a virulence factor that is found in (and released from) the cell walls of Gram-negative bacteria.
endotoxin
The molecules on the surfaces of host cells that pathogens are able to recognize and attach to are known as receptors or _____
adhesions
Molecules on the surfaces of pathogens that are able to recognize and bind to molecules on the surfaces of host cells are known as ligands or _________.
integrins
_______ is also known as “spreading factor.”
hyaloronidase
_____ are toxins that destroy white blood cells
leukocidins
T/F Bacterial capsules protect bacteria from being phagocytized by leukocytes.
TRUE
T/F A headache is a classic example of a sign of a disease.
FALSE
T/F In order to cause disease, all bacterial pathogens must first attach to some tissue in the body.
FALSE
T/F Rickettsias and chlamydias are examples of obligate intracellular pathogens
TRUE
T/F Babesia spp., Ehrlichia spp., and Plasmodium spp. are examples of intraerythrocytic pathogens.
FALSE
T/F The exoenzyme that causes toxic shock syndrome is called erthyrogenic toxin.
FALSE
T/F The neurotoxins produced by Clostridium botulinum and Clostridium tetani cause a spastic, rigid type of paralysis.
FALSE
T/F Although most people use the terms “infection” and “infectious disease” synonymously, microbiologists define infection as colonization by a pathogen.
TRUE
T/F Avirulent strains do not cause disease.
TRUE
T/F It is thought that the waxes in the cell walls of Mycobacterium tuberculosis protect this pathogen from digestion within phagocytes.
TRUE
Microbe lacks the ability to cause disease
avirulent
Establish microbial growth on a body surface
colonization
Able to produce disease in a host with impaired defenses
opportunist
Disease Causing Organism
Pathogen
T/F The most successful parasites are the ones that live in harmony with their hosts.
TRUE
T/F Infection always leads to disease.
FALSE
T/F A disease is an infection that impairs the normal state of health.
TRUE
T/F Obligate intracellular parasites may be grown in special synthetic media
TRUE
T/F The infectious dose of most pathogens is about equal.
FALSE
T/F A strong attachment of a microorganism to a host cell automatically leads to disease
FALSE
T/F High concentrations of some bacteria are necessary for successful invasion because only at high density are their virulence genes expressed.
TRUE
T/F Only gram + bacteria produce exotoxins
FALSE
The toxin implicated in C. perfringens toxicity is A. tetanospasmin. B. exoenzyme S. C. alpha-toxin phospholipase D. endoenzyme T.
alpha-toxin phospholipase
Which of the following produces a greenish pigment that may appear in infected wounds? E. coli S. aureus S. pyogenes P. aeruginosa
P. aeruginosa
Effective treatment of gas gangrene primarily involves
- use of an antitoxin.
- use of immune globulins.
- vaccination with inactivated toxin.
- surgical removal of dead and infected tissues.
surgical removal of dead and infected tissues.
The toxin implicated in C. perfringens toxicity is
- tetanospasmin.
- exoenzyme S.
- alpha-toxin.
- endoenzyme T.
alpha toxin
Tetanus antitoxin is
- antibody against the bacteria.
- inactivated toxin.
- inactivated bacteria.
- antibody against the toxin.
antibody against the toxin
Tetanus prevents the release of neurotransmitters from
- muscle cells.
- excitatory neurons.
- inhibitory neurons.
- tetano cells.
inhibitory neurons.
Wound infections may result in
• delayed healing.
• abscess formation.
• extension of bacteria or their products into surrounding tissues or bloodstream.
• aerobic conditions.
• delayed healing, abscess formation AND extension of bacteria or their products into surrounding tissues or bloodstream.
delayed healing, abscess formation AND extension of bacteria or their products into surrounding tissues or bloodstream.
Factor(s) not found in abscesses is/are
- pus.
- dead leukocytes.
- tissue remnants.
- blood vessels.
blood vessels
The normal habitat of Clostridium tetani ____ &___
soil and dust
What is associated with the flesh-eating organism?
Streptococcus pyogenes
. The Rickettsial disease that killed Howard Ricketts and Stanislaus Prowazek was
a. louse-borne typhus.
b. tick-borne typhus.
c. yellow fever.
d. bubonic plague.
louse-borne typhus.
Which of the following is considered an important function of the skin?
a. hold muscle to bone
b. manufacture blood cells
c. produce antibodies
d. control body temperature
control body temperature
- The antimicrobial aspect(s) of the skin is/are
a. dryness.
b. saltiness.
c. acidity.
d. toxicity.
e. all of the above
e. all of the above
Which of the following organisms is not normally found on the skin?
a. staphylococci
b. diptheroids
c. Candida spp.
d. Malassezia spp.
c. Candida spp.
Diphtheroids
a. are part of the normal flora of the skin.
b. are responsible for body odor.
c. include P. acnes.
d. include Malassezia spp..
e. a, b and c
e. a, b and c
Which of the following normal skin flora is a small yeast?
a. staphylococci
b. diphtheroids
c. Candida spp.
d. Malassezia spp.
Malassezia spp.
The growth of P. acnes within hair follicles, in many individuals, leads to
a. eczema.
b. carbuncles.
c. boils.
d. acne.
d. acne.
The principal species of Staphylococcus found on the skin is
a. aureus.
b. acnes.
c. pyogenes.
d. epidermidis.
d. epidermidis.
The bacteria that appear to maintain balance between the members of the normal flora and play a vital role in limiting colonization by pathogens are
a. staphylococci.
b. diptheroids.
c. Candida spp.
d. Malassezia spp.
a. staphylococci.
Which of the following may be added to normal media to make it more selective for staphylococci?
a. 7.5% salt
b. 0.5% HCl
c. 1.0 % glucose
d. 5.0% mannose
a. 7.5% salt
The member of the normal flora sometimes considered responsible for tinea versicolor is
a. staphylococci.
b. diptheroids.
c. Candida spp.
d. Malassezia spp.
d. Malassezia spp.
Which is deemed the most serious staphylococcal skin infection?
a. tinea versicolor
b. folliculitis
c. furuncles
d. carbuncles
d. carbuncles
A protein associated with a more virulent form of Staphylococcus is
a. leukocidin.
b. mannose.
c. streptokinase.
d. coagulase.
d. coagulase.
