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?
- yellow
- 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.)
Exfoliatins
Cytolysins - 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?
-
surgery
neuropenia
IV drug Abuse
chronic granulomatous disease - What are the six diseases caused by staphylococci?
-
Gastroenteritis
Infective endocarditis
abcesses/furuncles/carbuncles/styes
toxic shock syndrome
impetigo
pneumonia
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?
-
fever
systolic BP less than 90
rash
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?
- vancomycin
- 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?
hemolytic?
sensitivity?
catalase? -
group A
Beta hemolytic
Bacitracin sensitive
catalase negative - What diseases does Strep. pyogenes cause Acutely and non-acutely?
-
Acute
pharyngitis
scarlet fever
pyoderma/impetigo
necrotizing fasceitis (flash eating disease)
Non-acute
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
-
Alpha-hemolytic
Gram-positive
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?
- penicillin
- 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
or
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
PYR+
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
aerobic
large
only bacteria with polypeptide capsule instead of polysaccharide - What are the general characteristics of all Clostridium?
-
Gram-positive rod
spore forming
anaerobic - How would you identify all corynebacterium?
-
Gram-positive rods
non-spore forming, nonmotile
aerobic - 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
aerobic
motile
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?
-
actinomyces
nocardia - What are the five distinguishing characteristics of bacullus?
-
gram + rod
spore forming
aerobic
large
capsule is polypeptide (protein) instead of carbohydrate - What are the obligate aerobic organisms?
-
mycobacterium
pseudomonas
bacillus - When is anthrax lethal?
- when it is breathed in. it is the pneumonia form that is very deadly
- how is an anthrx treated?
- penicillin
- What are the six distinguishing characteristics of listeria?
-
gram positive
non spore forming
facultative intracellular
parasite
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
nonmotile
aerobic
club-shaped
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?
-
Actinomyces
Bacteroides
Clostridium - 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?
- penicillin
- What are the three main distinguishing characteristics of nocardia?
-
Aerobic BACTERIA
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