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Microbiology Video 2


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What are the medically important staphlococci?
Staphlococcus aureus
Staphlococcus epidermidis
Staphlococcus Saprophyticus
Are staphlococcie catalase positive or negative?
catalase positive
Are streptococci catalase positive or negative?
catalase negative
Whis is the only Staphlococcus that is coagulase positive?
Staph. aureus
What does the Alpha toxin released by Staph aureus cause it to be on blood agar?
BETA hemolytic, because the alpha toxin lyses cells
What is the color of the colonies of Staph aureus on blood agar?
In summary, what does Ataph aureus look like on blood agar?
gram + cocci, in clusters, catalase positive, coagulase positive, and yellow pigment
What are the toxins that Staph Aureus releases?
Alpha toxin
Toxic Shock Syndrome Toxin (TSST)
Entertoxins (products with milk or egg products that allow the organism to grow. This toxin produces rapid diarrhea, vomiting, etc.)
Is Staph epidermidis coagulase positive or negative?
coagulase negative
When grown on mannitol salt how is staph aureus differentiated from staph epidermidis and why is this?
Staph aureus is mannitol salt positive which means it ferments mannitol and produces a yellow color on the salt.

Staph epidermidis is mannitol salt negative which mean that it does not ferment mannitol and thus does not produce the yellow color on mannitol salt.
What is the significance of Staphylococcus saprophyticus?
it causes urinary tract infections
What are the predisposing factors for Staph Aureus infections?
IV drug Abuse
chronic granulomatous disease
What are the six diseases caused by staphylococci?
Infective endocarditis
toxic shock syndrome
surgical infections
What toxins are the cause of the abscesses/furuncles/carbuncles/styes?
coagulase, probably the cytolysins
What is the number one cuase of acute endocarditis?
Staph aureus
What are some other disorders due to staph aureus?
abcess, osteomyelitis (bone infections), SSS (scalded skin syndrome)
What is Scalded Skin Syndrome due to?
The exfoliatin toxin produced by STAPH AUREUS
What toxin released by staph aureus acts like an endotoxin?
Toxic shock syndrome toxin
What is another name for gastroenteritis and how long does it take to take effect and what toxin produces it?
food poisoning takes approx. 2-6 hours to take effect and is causes by enterotoxin released from staphlococci
What is impetigo caused by
staph or strep
What are the signs and symptoms that point toward Toxic shock syndrome?
systolic BP less than 90
increased liver enzymes
respiratory distress
coagulation problems
What is staph notorious for?
spreading throughout the body after a surgery while we are immunocompromized.
What has the staphlococci obtained and how does this effect how we treat people with staph infections?
staphylococci have obtained a Beta lactamase plasmid which makes them resistant to pinacillin
What is the antibiotic of choice for staphylococci?
How are staphlococci differentiated from strep.?
Streptococci are catalase negative while staphlococci are catalse positive.

Staph is in clusters and strep is in chains.
How are the various Streptococci best differentiated?
Culture on blood agar. They will be either Beta, alpha, or gamma hemolytic.
what is the difference between beta, alpha, and gamma hemolytic?
Beta = clear (complete hemolysis)
Alpha = green (partial hemolysis)
Gamma = non-hemolytic
What is a good example of a beta hemolytic streptococcus?
group A Strep. pyogenes
What are good examples of Alpha hemolytic Streptococci?
Strep. pneumoniae
Strep. Salivarious
what is a good example of a gamma hemolytic streptococci?
enterococcus faecalis (aka. streptococcus faecalis) the enterococci belong to the streptococcaceae family
What are the streptococci divided into groups due to and what are these groups known as?
a carbohydrate in the cell wall and these groups are known as Lancefield's groups
What are the three important identification criteria for Strep pyogenes?
Lancefield Group A, Beta hemolytic, and Becitracin-sensitive
What are the three important identification criteria for Strep agalactiae?
Lancefield Group B, Beta hemolytic, and Bacitracin-resistant
What is the main disease that Strep. agalactiae is associated with?
neonatal meningitis
What characterizes Enterococcus faecalis?
Lancefield Group D, gamma hemolytic grows in high salt, is PYR test positive, and turns black in bile esculin
Which streptococci and not groupable into Lancefield groups?
Strep. Pneumoniae and Viridan Group
What are the important identification criteria for Strep viridans group?
They are not groupable, alpha hemolytic, not bile-soluble, and not inhibitied by optochin
What does S. pneumoniae look like under the microscope?
gram + cocci in pairs
What is special about the capsule of Strep pneumoniae?
it reacts in the quelin reaction. antibody react with the capsule and the capsule swells up.
How do we identify strep pneumonia (3 things)?
it is alpha hemolytic, soluble in bile, inhibited by optochin
How is the Viridans group of strep grouped?
not groupable
What are good examples of Streptococci in Viridans group?
Strep. mutans
Strep. salivarius
How is Viridan group similar to and distinguished from S. pneumoniae?
Both are Alpha hemolytic
How to distinguish?
Strep viridans is not bile soluble, and is not sensitive to optochin
What are the characteristics of Strep. pyogenes?
group A
Beta hemolytic
Bacitracin sensitive
catalase negative
What diseases does Strep. pyogenes cause Acutely and non-acutely?
scarlet fever
necrotizing fasceitis (flash eating disease)

Rheumatic fever
Acute glomerulonephritis
What is the capsule of Strep pyogenes composed of?
Hyaluronic Acid - non-immunogenic
What is an important antiphagocytic protein in the cell wall of Strep. pyogenes?
M protein
What are the important toxins produces by Strep pyogenes and why are these toxin important?
Streptolysin O
Streptolysin S
these are the toxins that produces rheumatic fever and the body produces antibodies to streptolysin O, the production of this antibody indicates a poor prognosis
Erythrogenic toxin from strep pyogenes results in what and what is the main sign?
Scarlet fever which is identified by a strawberry tongue
What are the major characteristics of Strep. agalactiae
Group B
Beta hemolytic
Catalase negative
resistant to bacitracin
What does S. agalactiae colonize and what does this result in?
S. agalactiae colonizes the vagina and thus can infect a newborn during a long birth, obstetric problem, etc.
What diseases does S. agalactiae cause?
Neonatal septicemia and meningitis
What is hte most common cause of neonatal septicemia and meningitis?
Group B Strep.
What are the major characteristics of Strep. Pneumoniae (4) things
inhibited by optochin
lysed by bile
What are the three diseases the Strep Pneumonia causes?
Bacterial Pneumonia
Adult Meningitis
Otitis Media and Sinusitis in Children
What would you see in a person with Strep pneumonia?
RUSTY SPUTUM, chills, fever, alcoholic, smoker, and elderly individual
what is a very effective antibiotic agains Strep pneumoniae and most of the streptococci?
What is the best prevention for strep. pneumonia?
vaccine with 23 serotypes of capsule.
What are the strep. in the group Viridans Streptocooci?
S. sanguis
S. mutans
S. salivarius
What does Strep. mutans cause?
dental caries
What are the distinguishing characteristics of Viridans Streptococci?
Alpha-hemolytic, resistant to optochin
If what organism gets in the blood stream and goes to a damaged value it causes infective endocarditis?
strep salivarius
enterococcus faecalis
What characterizes entercoccus faecalis and what is it also, formerly, known as?
It was formerly known as streptococcus faecalis and it is characterized by being
catalase negative
gamma hemolytic
bile esculin positive (bile esculin agar burns black)
growns in high salt media
What Lancefield group is entercoccus in?
group D
What are some signs and symptoms of subacute bacterial endocarditis?
oslers nodes
splinter hemmorraging of big toe
What is the big problem in the treatment of enterococcus faecalis?
it has developed resistance to penicillin and that must be treated with vancomycin
What are the two spore forming bacteria?
bacillus and clostridium
What three things characterize Bacillus?
Gram +
spore forming
only bacteria with polypeptide capsule instead of polysaccharide
What are the general characteristics of all Clostridium?
Gram-positive rod
spore forming
How would you identify all corynebacterium?
Gram-positive rods
non-spore forming, nonmotile
what are the distinguishing characteristics of corynebacterium diphtheriae?
club shaped
granules stain metachromatically
What must diphtheriae have in order to produce the toxin?
Toxin producing strains have Beta prophage
What type of toxin is diphtheria toxin and what does it do in the cells?
it is an AB toxin which halts protein synthesis by binding ADP rybose to EF-2.
What rae the characteristics of listeria?
non-spore forming
intracellular growth by escaping phagosome beofre phagosome-lysosome binding
What gets infected with listeria?
Immunocompromised host
Which organisms are many times called fungi but are actually gram positive rods?
What are the five distinguishing characteristics of bacullus?
gram + rod
spore forming
capsule is polypeptide (protein) instead of carbohydrate
What are the obligate aerobic organisms?
When is anthrax lethal?
when it is breathed in. it is the pneumonia form that is very deadly
how is an anthrx treated?
What are the six distinguishing characteristics of listeria?
gram positive
non spore forming
facultative intracellular
tumbling motility
beta hemolytic
cold growth
Where do we find listeria?
Digestive tract of most animals
unpasturized milk
What are the two major problems in neonatal meningitis?
listeris and Group B Strep. agalactia.
Why is listeria so dangerous in neonatal meningitis?
it crosses the placenta
Describe the onset of neonatal meningitis due to listeria.
it can be either early (in utero transmission) or late onset ( 2 to 3 weeks)meningitis
What are the six distinguishing characteristics of corynebacterium?
Gram + rods
grows on tellurite medium
Granules (volutin) stain metachromatically (darker color at each end of the club)
What must the corynebacterium contain in order to produce the toxin?
Toxin-producing strains have Beta-prophage
What does corynebacterium look like on tellurite medium?
black colonies
how is corynebacterium spread?
respiratory spread. it gets into the throat, starts divinding and then produces one of the strongest toxins there is.
What does the corynebacterium diphtheriae toxin do?
inhibits protein systhesis
When the diphtheria toxin spreads, what does it mainly effect?
heart tissue
What is the main symptom of diphtheria look like and why is it dangerous?
dirty grey pseudomembrane which can spread to the larynx/trachea and cause obstruction
What is the test used to identify diphtheria?
Elek plate test
What are the main three anaerobes?
What are the three main identifying characteristics of actinomyces?
Anaerobic BACTERIA
Gram-positive rods to branching filaments
Where do we get actinomyces from?
Gingival crevices and female genital tract
What does an actual actinomyces infection look like?
Tissue swelling, which leads to draining abcesses. Inside the fluid drained from the abcesses are HARD YELLOW MICROCOLONIES (SULFUR GRANULES)
When does an actinomyces infection usually occur and what is it known as?
Occurs after a tooth extraction and is known as lumpy jaw.
What is the treatment for an actinomyces infection?
What are the three main distinguishing characteristics of nocardia?
Gram positive filaments breaking up into rods
partially acid-fast
How do we get Nocardia?
Comes through the soil. Ususally through a wound
Although actinomyces looks similar, how do you traeat nocardia?
sulfonamides: trimethoprim/sulfamethoxazole

you do not use penicillin for nocardia.
How would you identify mycobacterium?
Acid fast rods
obligate aerobe
What is unique to mycobacterium?
high concentration of lipids contain long chain fatty acids called MYCOLIC ACIDS
What is the pathogenic element of mycobacterium?
CORD FACTOR, the mycolic acids organized themselves into what is known as cord factor
What are the five distinguishing characteristics of Mycobacterium tuberculosis?
Auramine-rhodamine staining bacilli
Acid Fast
Aerobic, grows on Lowenstein-Jensen medium
Produces niacin
heat-sensitive catalase (other mycobacterial catalases are heat insensitive)
In what population is Mycobacterium TB prevalent in?
immunocompromised (HIV)
How do we test for mycobacterim TB?
x-rays and PPD skin test

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