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135 Cards in this Set

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Describe Staphylococci:
-Spherical cells arranged in irregular clusters
-Gram +
-Catalase Positive
-non motile
-Common Inhabitant of the skin and mucous membranes
-31 species
Are Staphylococci motile?
no, they lack flagella
Staphylococci is Catalase ___.
Staphylococci is Catalase Positive.
Staphylococci & Streptococci are both Gram + Cocci that can cause similar infections and be confused for one another. How do you tell them apart?
Staphylococci is Catalase Positive; Streptococci is Catalase Negative.
Enzyme that breaks down Hydrogen Peroxide.
Catalase
Major Pathogen in the Staphylococcus genus is:
Staphylococcus aureus
Describe Staphylococcus aureus:
Known for ability to grow in different environments:
-Wide temp. range: -10 to 46°C
-Facultative anaerobe
-withstands:
-high salt
-extremes in pH
-dessication
-Produces many virulence factors
What are the enzymes that are virulence factors for Staphylococcus aureus?
-Coagulase (diagnostic)
-Hyaluronidase
-Staphylokinase
-Lipases
-Penicillinase & other antibiotic resistance enzymes (MRSA)
What are Staphylococcus aureus' oxygen requirements?
He is a facultative anaerobe
Why is Coagulase diagnostic?
Because Staphylococcus aureus is the only species in the Staphylococcus genus that produces Coagulase.
What do Staphylococcus aureus Exoenzymes do?
-Coagulase (diagnostic): coagulates plasma (forms clots)
-Hyaluronidase: Digests basement membrane & tissue aka Spreading Factor
-Staphylokinase: Digests blood clots
-Lipases: Digest lipids
-Penicillinase & other antibiotic resistance enzymes (MRSA)
Explain why Staphylococcus aureus wants to make Coagulase which forms blood clots, and also Staphylokinase which digests blood clots.
It depends on where it is in the infection cycle.
Coagulase is useful to protect it from WBCs. So, early on in the infection, it forms clots to slow/block WBC from reaching it.
Later on in the infection, Staphylokinase (as well as Hyaluronidase) is made to break down blood clots to allow Staphylococcus to spread.
One of the reasons that Staphylococcus can survive on our skin is that:
it produces Lipases, which break down oils in the skin, allowing it to survive.
MRSA stands for:
Multi-drug Resistant Staphylococcus Aureus.
Is Staphylococcus aureus good at developing anti-biotic resistance?
Yes
What are the toxins produced by Staphylococcus aureus?
-Toxic shock syndrome toxin
-Hemolysins
-Enterotoxins
-Exfoliative toxin
-Leukocidin
What do the toxins produced by Staphylococcus aureus do?
-Hemolysins: lyse RBCs
-Leukocidin: lyse WBCs
-Enterotoxins: toxins that act on the GI tract
-Exfoliative toxin: separates dermis from epidermis (skin peels off in sheets)
-Toxic shock syndrome toxin: causes severe systemic effects
Enterotoxin symptoms include:
Vomiting, nausea, stomach cramps, diarrhea.
Toxic shock syndrome toxin symptoms include:
Vomiting, nausea, fever, rash. Multi-system, severe toxin.
All of the toxins released by Staphylococcus aureus are:
Exotoxins
What are the types of Local S. aureus infections?
Abscesses & Impetigo
Define abscess:
A localized lesion with puss.
What are the types of abscesses caused by S. aureus:
Furuncles & Carbuncles
What is a Furuncle?
What is a Carbuncle?
A Furuncle is an infected hair follicle.
A Carbuncle
Furuncle aka:
a boil
What is a Carbuncle?
Multiple furuncles grouped together.
Describe Impetigo:
S. aureus infection of the epidermis. Identified as crusty, yellow lesions.
Impetigo most commonly infects:
Newborns, usually because they don't have microflora to protect them yet.
What are some systemic S. aureus diseases?
-Bacteremia
-Endocarditis
-Osteomyelitis
Define Bacteremia:
Bacteria in the blood stream.
How does S. aureus enter the bloodstream?
From a Furuncle or an open wound.
When S. aureus enters the bloodstream, what are its two favorite locations to set up infection?
The Endocardium & the bones.
Describe Endocarditis :
Infection of the heart lining.
Describe Osteomyelitis:
Bacterial infection of the bones.
In Osteomyelitis, bacteria can grow so quickly that it can cause:
breaks in the bones.
The main culprit for Osteomyelitis is:
S. aureus
What are the Toxigenic S. aureus diseases?
-Food Intoxication
-Scalded Skin Syndrome
-Toxic Shock Syndrome
Describe Food Intoxication:
When S. aureus grows in a high carbohydrate environment, it releases an Enterotoxin. This Enterotoxin causes gastroenteritis: Nausea, Vomiting, Diarrhea, Stomach cramps etc. within hours. Recovery in days.
Describe Scalded Skin Syndrome:
S. aureus is growing on skin and releasing Exfoliative Toxins which cause the separation of the dermis from the epidermis.
- Very Painful
When does S. aureus release Toxic Shock Syndrome toxin?
Toxic Shock Syndrome toxin can be released when S. aureus is growing in a nutrient rich environment.
Describe Toxic Shock Syndrome:
Fever, vomiting, Rash, Damage to multiple organs, & death without treatment.
Describe Toxic Shock Syndrome toxin assoc. w/ tampon use:
Back in the 80s, tampon formulations actually encouraged the growth of S. aureus, which would produce the Toxic Shock Syndrome Toxin in the high nutrient environment of menstrual fluids.
What has been done now to reduce the risk of Toxic Shock Syndrome toxin?
Tampons are now formulated differently to discourage the growth of S. aureus. New guidelines suggest leaving a tampon in for no longer than 8 hrs. However, the #1 risk factor for Toxic Shock Syndrome is tampon use, so the risk factor is still there.
S. aureus is the bad guy in the 31 species of Staphylococcus, but some other species that can cause infection are:
However, these are thought of as:
-S. hominis
-S. capitis
-S. saprophyticus
-S. epidermidis
These are thought of as: opportunistic pathogens.
How do you test a patient to see if they have S. aureus, or the less dangerous opportunistic species of Staphylococcus?
Test for Coagulase. Remember, Coagulase is diagnostic* for Staphylococcus aureus. The others are Coagulase Neg.
If a patient comes in with a Gram + cocci infection, the first question is?
Is it Staphylococcus or Streptococcus.
What's the first thing you do to distinguish Staphylococcus from Streptococcus?
Catalase test
Staphylococcus is Catalase___.
Streptococcus is Catalase ___.
Staphylococcus is Catalase +
Streptococcus is Catalase –
If the Catalase test comes back +, the next question is?
If the Catalase test comes back +, we know it is in the Staphylococcus genus. Now we need to find out if it is the nasty S. aureus or one of the opportunistic Staphylococcus species.
How to distinguish S. aureus from the other opportunistic species of Staphylococcus?
Coagulase test; if result is Coagulase + then it is S. aureus
A Staphylococcus species makes Coagulase, therefore it is Coagulase ___ and its name is ____________.
A Staphylococcus species makes Coagulase, therefore it is Coagulase + and its name is Staphylococcus aureus.
Describe Streptococci:
-Spherical to Ovoid cocci in chains
-Gram +
-Catalase Neg.
-Non-spore forming/Non-motile
-Most pathogenic forms are fastidious
-25 species
Fastidious means:
difficult to grow.
Describe the difference between Staphylococci & Streptococci in regards to their growth tolerances:
Staphylococci are very hearty.
Streptococci are fastidious.
What are the classification methods for Streptococci?
-Lancefield classification system based on cell wall
-Hemolytic pattern classification
Describe the Lancefield classification system:
Where is this used?
What is used in the scientific community?
The Streptococci are classified according to their cell wall and organized into 14 groups: Group A strep, Group B strep, etc.
This classification system is used in the Medicine. The species names are used instead in the scientific community.
Many species of Streptococci are hemolytic, meaning they can:
break down RBCs.
-partial hemolysis of blood is called:
-complete hemolysis of blood is called:
-partial hemolysis of blood is called: α-hemolysis
-complete hemolysis of blood is called: β-hemolysis
Describe the α-hemolysis pattern:

What is happening?
A khaki-green colored halo around the colony.
What's happening is that the colony is releasing hemolysins; chemicals that lyse the RBCs but they do it incompletely, leaving a khaki-green colored halo around the colony.
The Streptococcus that causes Strep throat is ___-hemolytic.
β-hemolytic
Describe the β-hemolysis pattern:
There is complete hemolysis of the blood cells, leaving clear halo around the colony. You can see through the plate.
The major pathogen in the Streptococcus genus is:
S. pyogenes
S. pyogenes
Lancefield classification is:
Hemolytic pattern classification is:
Lancefield classification is: Group A
Hemolytic pattern classification is: β-Hemolytic
Streptococcus species that is Group A strep and β-Hemolytic is:
Streptococcus pyogenes
Describe Streptococcus pyogenes:
-Reservoir of infection:
-Surface antigens:
-Exoenzymes:
-Toxins:
-Strict parasite (ie. not found on countertops) very picky and quite fastidious
-Reservoir of infection: throat, nasopharynx, sometimes skin (face & genitals)
-Surface antigens: C-carbohydrates & M-protein (his type of fimbrae)
-Exoenzymes: Hyaluronidase & Streptokinase
-Toxins: Hemolysins & Erythrogenic Toxin
Describe the Surface Antigen, C-carbohydrate:
It is S. pyogenes' particular type of teichoic acid.
What are teichoic acids?
They are only found in?
They are the molecules that hold peptidoglycan onto the cell membrane.
Only found in Gram + bacteria.
Organism that requires growth factors present in their environment in order to grow:
Fastidious organisms
What does C-carbohydrate protect S. pyogenes against?
Lysozyme
What is Streptokinase?
An enzyme produced by S. pyogenes that digests blood clots.
The quintessential test for S. pyogenes is:
to test for β-hemolysis
Describe Erythrogenic Toxin and its bizarre formation:
Erythrogenic Toxin creates the "Scarlett Fever" rash and is only created by S. pyogenes that has been infected by a bacteriaphage.
What are some localized S. pyogenes diseases?
-Impetigo
-Erysipelas
-Pharyngitis (Strep throat)
What is Erysipelas?
How is it caused?
What is the classic sign?
When the bacteria is growing in the dermis. Usually caused by the bacteria entering into a cut or puncture wound. The classic sign of Erysipelas is: a super-hot, red rash.
What are the symptoms of Strep-throat?
-Really dark red in back of throat (so red its almost purple)
-Puss patches
-Rotten smell from patients mouth
-Nausea, headache, Fever, swollen lymph nodes.
Possible complications of strep-throat can lead to:
Systemic S. pyogenes diseases
What are some Systemic S. pyogenes diseases? (possible complications of strep-throat)
Scarlet fever & rheumatic fever
Scarlet fever causes a rash all over the body, but the easiest place to see it is on the:
Tongue; causes strawberry tongue
Describe Strawberry Tongue:
Tomato red tongue with the skin peeling off.
Is rheumatic fever only caused by S. pyogenes that has been infected by a virus?
No; it can be caused either way.
Describe Rheumatic fever:
S. pyogenes enters the bloodstream. It theoretically could go anywhere once in the bloodstream, but it likes to set up infection in the heart valves, where it can damage them.
One reason to be quick to prescribe anti-biotics is to fight:
Strep-throat.
Is Necrotizing Fasciitis a complication of Strep throat?
No, it is due to S. pyogenes entering in through a deep wound.
Describe Necrotizing fasciitis:
S. pyogenes enters through a deep wound. He releases Streptokinase, Hyaluronidase & Hemolysin. As the bacteria grows, it shows an unbelievable ability to digest through all tissues, even bone.
How is Necrotizing Fasciitis treated?
All of the dead tissue and bacteria is removed and the patient is treated aggressively with anti-biotics.
The severity of Necrotizing Fasciitis is depends entirely on:
the location of the infection
The Enterococci genus is closely related to:
Streptococci
What are the two species of Enterococcus lectured?
Enterococcus faecalis & Enterococcus faecium
Describe Enterococcus faecalis & Enterococcus faecium:
-Normal colonists of the human large intestine
-Cause opportunistic urinary, wound, & skin infections.
Are the Viridians Group of Streptococci the same species?
No, but they are so closely related, have so many similarities, cause the same infections, and are so difficult to distinguish from one another, that they are grouped together.
Describe the Viridians Group of Streptococci..
Reservoir:
Hemolytic pattern:
Invasiveness:
-Most numerous & widespread residents of the oral cavity, nasopharynx, genital tract, & skin.
-α–hemolytic
-Not very invasive but Dental or surgical procedures can facilitate entrance.
If the Viridians Group get into the blood, their favorite location to set up infection is the:
Heart
What are the Viridians Group diseases?
-Subacute endocarditis
-Tooth abscesses
-Abdominal infection
-Bacteremia
-Dental Carries
-Meningitis
Describe Sub-acute endocarditis:
Blood borne bacteria settle & grow on heart lining or valves.
What is the #1 cause of heart murmurs in the US?
Endocarditis by either S. pyogenes or the Viridians group.
Describe Streptococcus pneumoniae:
-Small, lancet-shaped cells in pairs and short chains
-A causative agent for pneumonia: Causes 60-70% of all bacterial pneumonias.
-ALL pathogenic strains form large capsules (*major virulence factor*)
Define Pneumonia:
Inflammatory fluids in the lungs.
S. pneumoniae is known for:
having a HUGH capsule (major virulence factor)
The 84 capsular types of S. pneumoniae can be identified using the _____________ test.
Quellung test
How does S. pneumoniae cause pneumonia?
Occurs in people who carry S. pneumonia in the flora of their Upper Respiratory Tract. Another infection or allergies causes the S. pneumonia to travel into the lungs in mucus. This causative agent for pneumonia is NOT contagious.
What are the signs of pneumonia?
-Difficulty breathing
-Chills
-Shaking
What are some infections caused by S. pneumoniae?
-Pneumonia
-Otitis Media (ear infection)
-Meningitis
Describe Otitis Media caused by S. pneumoniae:
Symptoms:
S. pneumonia as flora in the Upper Respiratory Tract moves up the Eustachian tube and sets up infection.
-Symptoms: Pain, inflammation, & fluid build up.
Why are kids at a higher risk for ear infections?
They have a shorter eustachian tube, ∴ there is less distance for the bacteria to travel.
Is there a vaccine available for S. pneumoniae?
Yes, it is suggested for children at the highest risk for S. pneumoniae ear infections and meningitis.
Staphylococci and Streptococci are Gram__.
Gram +
Enterococci are Gram__.
Gram+
Neisseria is Gram__.
Gram –
Describe the Neisseria genus:
-Gram Neg. diplococci
-Lack flagella and spores
-Pathogens have capsules and pili (pili are also used for attachment)
-Strict parasites
Describe the reservoir for Neisseria:
They are strict parasites that reside in mucous membranes. They cannot live outside the body. Cannot be transferred by fomites. Only transferred by direct contact.
Classic pathogen in the Neisseria genus is:
Neisseria Gonorrhoeae
Describe Neisseria Gonorrhoeae...
Causes what?
Virulence factors:
Species infected:
Survival outside the body/fomites
asymptomatic prevalence?
-Causes the STD Gonorrhea
-Virulence Factors: Pili & IgA Protease
-Strictly a human infection
-Does not survive longer than 1 -2 hrs. on fomites.
-Infection is asymptomatic in 10% of males and 50% of females.
Major symptom associated with Gonorrhea is:
-Tons of puss production
-Painful urination
What is IgA Protease?
An Exoenzyme made by Neisseria Gonorrhoeae that degrades IgA.
Describe Gonorrhea contraction in males:
Bacteria enters urethra causing Urethritis. Untreated, it can move up from the urethra to the vas deferens and testis.
Define Urethritis:
The infection and inflammation of the urethra.
Long term infection of Gonorrhea can lead to:
Scar tissue formation in the vas deferens causing infertility.
Describe Gonorrhea contraction in females:
There are two possibilities:
1) it can set up infection in the urethra causing urethritis.
2) it can set up infection in the vagina causing vaginitis.
What are the symptoms of female gonorrhea?
Whether the infection sets up in the vagina or urethra, the symptoms are the same:
-Puss production
-Painful urination
-Painful sexual contact
Describe long term infection of gonorrhea in females:
The bacteria can make its way up past into the higher reproductive organs, past the cervix, and infect the mucosa of the uterus, or infect the fallopian tubes or even cross to the ovaries.
What are the dangers of long term infection of gonorrhea in females:
Scar tissue can develop in the uterus, ovaries, or fallopian tubes causing infertility or sterility. Scar tissue in the fallopian tubes can lead to ectopic pregnancies.
Infection in the fallopian tubes, ovaries, or uterus lining is called:
Salpingitis or Pelvic Inflammatory Disease (PID)
Describe Gonorrhea in newborns:
Babies can be infected from the mom as they pass through the birth canal. If not treated quickly, can lead to blindness. Positive mothers can be given anti-biotics before birth. anti-biotic eye drops are given prophylactically to baby upon birth.
How many new cases of gonorrhea every year?
about 2 million, making gonorrhea 1 of the top 5 STDs in the US.
Describe immunity against gonorrhea:
immunity doesn't last very long. Memory B response isn't very strong. If you get gonorrhea, you can get it again.
Describe Neisseria Meningitidis...
How many strains?
Causes what disease?
Do vaccines exist?
-Virulence Factors: Capsule, pili, IgA Protease, Endotoxin
-12 strains; serotypes A,B,&C cause most cases
-prevalent cause of meningitis
-vaccines exist for group A and C.
Some people carry Neisseria Meningitidis as the normal flora in their:
nasopharynx.
The high-risk demographic for Neisseria Meningitidis is:
Young adults
Describe infection by Neisseria Meningitidis:
A carrier of Neisseria Meningitidis comes into close contact with a non-carrier. They inhale the bacteria in, the bacteria enters the bloodstream and crosses the blood-brain barrier and set up infection in the meninges. The bacteria then releases ENDOTOXIN.
Define Meningitis:
Infection of the meninges, the membranes that surround the brain and spinal cord.
Describe the symptoms of meningitis:
-Fever
-Headache
-Chills
-Delirium
-Shock
-Death
Can go down the spinal cord
What other pathogen besides Neisseria Meningitidis can cause meningitis?
S. pneumoniae
The group at the highest risk for meningitis from Neisseria Meningitidis is:
Young adults living in close quarters: college students living in dorms, military recruits.
Neisseria Meningitidis aka
Neisseria Meningicoccus
Is there a vaccine for Neisseria Meningitidis?
Yes, its called the Meningicoccus vaccine. Many colleges are requiring students to get it before they come to campus.