Bacterias Flashcards
STAPHYLOCOCCUS AUREUS
“The golden staff of Moses”
STAPHYLOCOCCUS AUREUS
“The golden staff of Moses”
What does Staphylococcus Aureus literally mean?
Staphylococcus (grape like)
Aureus (gold in color)
Gram type of Staphylococcus Aureus?
Gram Positive Cocci
What tests can be used to determine Staphylococcus Aureus?
Catalase (+)
Coagulase (+)
Beta Hemolytic (+)
Mannitol (+)
What is the main virulence factor on Staphylococcus Aureus and how does it work?
Protein A; Main virulence factor on staph aureus.
Protein A is a component of S. Aureus cell wall and
it can bind to the FC region of antibodies and this will prevent compliment from occurring.
Preventing opsonization and phagocytosis.
Where does Staphylococcus Aureus mainly colonize?
S. Aureus will colonize the nares
What are the 10 possible diseases that can be caused with Staphylococcus Aureus?
- Gastroenteritis
- Acute bacterial endocarditis
- Abscesses and mastitis (Humps with red cloth - Really large erythematous abscesses)
- Toxic shock syndrome
- Impetigo
- Scalded Skin Syndrome (SSS)
- Pneumonia
- Surgical infections
- Osteomyelitis
- Septic Arthritis
What causes the coughing in Staphylococcus Aureus infection?
Coughing - Pneumonia
Patchy infiltrate on x-ray
What is the shape of the capsule of the virus that will infect after a Staphylococcus Aureus infection?
Icosahedron shaped capsule of the virus that will infect after a S. Aureus infection.
What is Staphylococcus Aureus is the most common cause of in adults? (Hint: 2 diseases)
Septic Arthritis and Osteomyelitis.
In Staphylococcus Aureus acute endocarditis, what is the most common cause of it and where does it affect it in the heart?
IV drug use
Tricuspid valve Endocarditis
What mediates Scalded Skin Syndrome in a Staphylococcus Aureus infection?
Scalded skin syndrome mediated by a protease
What causes Toxic Shock Syndrome in a Staphylococcus Aureus infection?
Toxic Shock Syndrome, commonly caused by leaving a bandage in or a tampon which causes nonspecific binding of MHC II to T cell receptors causing over-reaction and Cytokine storm.
What does a Catalase test measure?
Turns hydrogen peroxide –> water
What does a Coagulase test measure?
Fibrinogen –> fibrin
What does a Beta Hemolytic test measure?
When looking at petri dish with B-hemolysis it looks like a glowing halo of light.
Beta-hemolysin breaks down the red blood cells and hemoglobin completely. This leaves a clear zone around the bacterial growth.
What does a Mannitol test measure?
If it CAN ferment manitol it will turn the agar to yellow.
If it CAN’T ferment manitol the agar will stay pink.
What is the treatment of choice for Staphylococcus aureus infection?
Nafcillin/oxacillin are drugs of choice because of widespread antibiotic resistance.
“Naf for Staph”
What is the treatment for methicillin-resistant Staphylococcus aureus (MRSA)?
Vancomycin
What is the treatment for vancomycin-resistant Staphylococcus aureus (VRSA) or vancomycin- intermediate S. aureus (VISA)?
quinupristin/dalfopristin
STAPHYLOCOCCUS EPIDERMIDIS AND STAPHYLOCOCCUS SAPROPHYTICUS
“Beauty and the Plumber”
STAPHYLOCOCCUS EPIDERMIDIS AND STAPHYLOCOCCUS SAPROPHYTICUS
“Beauty and the Plumber”
Staphylococcus epidermidis and Staphylococcus saprophyticus are what type of gram?
Gram (+)
Staphylococcus epidermidis and Staphylococcus saprophyticus are Catalase + or -?
Catalase Positive
Staphylococcus epidermidis and Staphylococcus saprophyticus are Urease Positive. What does that mean?
Urea –> ammonia
How are Staphylococcus epidermidis and Staphylococcus saprophyticus separated from staph aureus?
Staph epidermidis and Staph saprophyticus are coagulase negative
Why is Staphylococcus epidermidis considered Ortopedic’s enemy?
- Hardware - Infects hardware or orthopedic joints
- Tubing - Catheter tubes, Indwelling catheters are also important spots of infections
- Heart valves - Infection of heart implants - endocarditis of artificially implanted heart valves
How is Staphylococcus epidermidis able to affect tools?
Uses biofilms to stick to sleek metal and plastic surfaces, these are polysaccharides that protect them from antibiotics and immune cells.
TXT of Staphylococcus Epidermidis endocarditis?
Vancomycin for TXT of Staph Epidermidis endocarditis
Where can Staphylococcus Epidermidis be found?
Normal Skin Flora
Staphylococcus Epidermidis is sensitive or resistant to a certain drug?
Novobiocin Sensitive
What disease is mainly caused by Staphylococcus saprophyticis infection?
UTI’s in Sexually Active Females.
Staphylococcus saprophyticis is sensitive or resistant to a certain drug?
Novobiocin resistant
Who is more at risk for Staphylococcus sapropytics infection?
Sexual active females
GROUP A STREPTOCOCCUS (STREPTOCOCCUS PYOGENES)
“The Pie Genies’ Bakery”
GROUP A STREPTOCOCCUS (STREPTOCOCCUS PYOGENES)
“The Pie Genies’ Bakery”
Group A Streptococcus are:
encapsulated or no capsulated?
Encapsulated
What is the capsule of the Streptococcus Pyogenes made of?
Hyaluronic Acid
Where do we produce Hyaluronic Acid in our bodies?
Connective Tissue so everywhere in our body so it cannot be immunogenic or else our own immune system would constantly be attacking us.
What tests can be done with Streptococcus Pyogenes?
B-Hemolytic
What are the symptoms Streptococcus Pyogenes can cause?
Impetigo
Pharyngitis (aka Strep throat), red inflamed throat
Erysipelas (its a very superficial cellulitis infection), red lesion with well demarcated borders, S Pyogenes is the most common cause.
What is the toxin of the Streptococcus Pyogenes?
Streptococcal Pyrogenic Exotoxin (SPE)
SPE A
SPE B
SPE C
What are the diseases that can be caused by the Streptococcus Pyogenes toxin?
Scarlett Fever
Toxic Shock Like Syndrome (TSLS)
Necrotizing Fasciitis
What are the three main symptoms of Scarlett Fever?
a. “Strawberry Tongue” - reddening and swelling of the tongue
b. Pharyngitis
c. Diffuse (widespread) rash that spares the face.
What is Toxic Shock Like Syndrome mediated by?
Super Antigen SpeA, SpeC
What is the Necrotizing Fasciitis mediated by?
SpeB
What are the two highly tested conditions (complications) pretending to Streptococcus Pyogenes?
Rheumatic Fever (RF)
Post Streptococcus Glomerulonephritis (PSGN)
What is the main virulence factor for Rheumatic Fever and how does it function?
M protein in GAS (Group A Strep) is the main virulence factor for Rheumatic Fever, will interfere with opsonization, antiphagocytic, M protein will mimic antibodies in heart and cause issues with Mitral Valve in the heart.
How does M protein function?
Antiphagocytic action
Very antigenic and elicits a humoral response, creating an antibodies to a very similar antigen and in this case myosin in cardiac muscle (Molecular mimicry), thus, damages mitral valves (can cause a mitral stenosis)
Pharyngitis precipitates RF, NOT IMPETIGO
When does Rheumatic Fever occur?
AFTER Streptococcus pharyngitis infection.
Does NOT happen after skin infections.
Does NOT happen after prompt treatment of pharyngitis, which is why it happens more in young children with little access to Healthcare.
Pharyngitis precipitates RF, NOT IMPETIGO”
What kind of hypersensitivity reaction is Rheumatic Fever?
Hypersensitivity type II reaction
What is the criteria used for Rheumatic Fever?
JONES criteria
J: Joints –> polyarthritis
O: <3 : “heart problems” –> valvular damage leading to new murmurs, myocarditis, paricarditis.
N: Nodules (subcutaneous nodules): nodules on extensor surfaces (forearms, elbows, knees)
E: erythema marginatum: rash with nice thick borders
S: Sydenham’s Chorea: rapid involuntary especially of hands and face
What causes the Post Streptococcus Glomerulonephritis (PSGN)?
Our own immune system.
After a streptoccocus infection, unlike RF the damage isn’t a type2 hypersensitivity reaction, its a type 3 hypersensitivity, which means the damage is from circulating antibody antigen immune complexes that eventually deposit in the glomerulus.
What are the 2 main symptoms for Post Streptococcus Glomerulonephritis (PSGN)?
Facial edema - puffy cheeks w/ nephritis
Cola colored Urine
When does Post Streptococcus Glomerulonephritis (PSGN) occur?
Occurs 2 weeks after the onset of the initial streptococcus infection.
What is a way to differentiate RF and PSGN?
RF: can occur only after pharyngitis
PSGN: can occur after pharyngitis or superficial infection like impetigo
Treatment and complication prevention:
Early diagnosis and treatment of Strept throat can prevent RF but it cant prevent PSGN.
What is the treatment for Streptococcus pyogenes infection?
Penicillin
What are 3 more virulence factors for Streptococcus pyogenes?
a. Streptolysin O: allows Group A Streptococcus to lyse RBC to be Beta Hemolytic, we generate antibodies to Streptolysin O (called ASO antibodies).
b. Streptokinase, converts plasminogen to plasmin. Plasmin is fibrinolytic. So Streptokinase is given as medication to lyse clots to MI or Ischemic strokes.
c. DNA’ases, depolymerize DNA and really least important to know.
What does “kinase” mean?
To put a phosphate on something
How do we differentiate Group A Streptococcus and Group B streptococcus?
Group A Streptococcus is Bacitracin sensitive.
Group B Streptococcus is Bacitracin resistant.
How can we test if a patient recently had a Group A streptococcus infection?
Check ASO titers to see if there was a Group A Strep Infection since we create antibodies against it.
We generate antibodies to Streptolysin O (called ASO antibodies).
Antistreptolysin O titer
What is the Mnemonic for Virulence factors of Streptococcus pyogenes?
“SMASHED”
Streptolysins M protein Anti-C5a peptidase Streptokinase Hyaluronidase and Hyaluronic acid Capsule Exotoxin (SPE-A, SPE-B, SPE-C) DNAses
STREPTOCOCCUS AGALACTIAE
“Galactic Baby (Group B Streptococcus)”
STREPTOCOCCUS AGALACTIAE
“Galactic Baby (Group B Streptococcus)”
Streptococcus agalactiae is gram positive or negative?
Gram Positive (“purple plante”)
What tests can be done to check for Streptococcus agalactiae?
Hippurate Positive
CAMP test positive
B-hemolytic
What does a Hippurate test measure?
Hydrolyzes sodium hippurate.
What does CAMP test measure?
Distinguishes Streptococcus agalactiae with all other streptococcus!
Similar to staphylococcus Aureus, when GBS is plated with Staph aureus, it has increasing zone of hemolysis.
What kind of capsule does Streptococcus Agalactiae have?
Polysaccharide capsule
What does Bacitracin do to streptococcus agalactiae?
Nothing, its Bacitracin resistant.
What is the main concern with a streptococcus agalactiae and its also the first thing you should think about is:
Causes Meningitis in neonates (#1 cause of meningitis in neonates).
What else can streptococcus agalactiae also cause?
Most likely to cause meningitis sepsis and also causes pneumonia.
What can you see in petri dish of streptococcus agalactie?
a arrowhead is the arcuate that forms in the zone of hemolysis.
How can a neonate get a streptococcus agalactiae infection?
When neonates passes through the vaginal canal of the mother during delivery.
Part of prenatal care, how and when do we check for streptococcus agalactiae?
Week 35 the vagina and rectum is swabbed to see if she is colonized by streptococcus agalactie.
What is GBS infection?
Group B Strep infection
What is the prevention for streptococcus agalactiae?
Profilaxis: Penicillin will be given to mom intrapartum to prevent group B strep.
STREPTOCOCCUS PNEUMONIA & STREPTOCOCCUS VIRIDANS
“The Alpha Knight Tournament”
STREPTOCOCCUS PNEUMONIA & STREPTOCOCCUS VIRIDANS
“The Alpha Knight Tournament”
Is streptococcus pneumonia gram positive or gram negative?
Gram Positive
Is streptococcus pneumonia alpha or beta hemolytic?
a-hemolytic which means theres partial hemolysis where the surrounding zone is a green hue. This green comes from the oxidation from hemoglobin.
What kind of capsule does streptococcus pneumonia have and why is it important?
Polysaccharide capsule which is a major virulence factor.
Streptococcus pneumonia is sensitive to something. what is it?
Optochin sensitive, optochin inhibits the growth of streptococcus pneumonia
What does streptococcus pneumonia look like under a microscope?
“Double Lance” - Lancet shaped diplococci
Streptococcus pneumonia is soluble to what?
Bile soluble, meaning it does not grow in bile
What kind of pneumonia does streptococcus pneumonia lead to and how does the sputum look like?
Lobar pneumonia that generally infiltrates the lower lobes.
Rust colored sputum.
Streptococcus pneumonia is the number one cause of which diseases?
Community acquired pneumonia
"MOPS" Meningitis Otittis Media Pneumonia Sinusitis
Streptococcus Pneumonia has another virulence factor other than its capsule that helps it avoid our immune system. What is it?
IgA Protease: Protease that cleaves IgA that allows invasion of mucosa reducing host defenses.
Helps it invade and colonize our mucosa, reducing host’s defenses
Who is at a greater risk of getting infection of encapsulated microorganisms?
Spleenectomy or autospleenectomy as in the case of Sickle cell disease (asplenia). This is because the spleen plays a major role of removing encapsulated organisms from the body.
Removal of spleen leads to susceptibility of infection by encapsulated organisms like in sickle cell anemia.
What is the TXT for streptococcus pneumonia infection?
Macrolides (azithromycin)
3rd gen cefalosporin: Ceftriaxone
How can we prevent a streptococcus pneumonia infection?
Adult is a 23 valiant polysaccharide vaccine.
Children is 7 valent but conjugated to a protein.
Adults will have a T-Cell independent response creating IgM that does not last long. Adding the protein adds a more robust antigen response leading to a production of IgG in children.
What kind of capsule does Streptococcus viridians have?
its NOT encapsulated
Streptococcus viridians is resistant to what?
optochin
What happens to streptococcus viridians when it is put with bile?
it is resistant
What other species are part of the streptococcus viridans?
Streptococcus mutants
Streptococcus sanguinis
What can streptococcus mutants and Streptococcus sanguinis lead to?
dental plaque, dental carries
What happens if Streptococcus viridian gets in the blood?
subacute endocarditis in damaged heart valves most commonly mitral valve.
Strep Sanguineous adheres to fibrin platelet aggregates in damaged heart valves, most commonly occurs in mitral valve.
How can Streptococcus viridians do so much damage to the heart?
Synthesizes Dextran’s (think of it like a glue) from glucose which allows strep viridians to adhere to any fibrin from platelets that has been damaged in the heart.
ENTEROCOCCUS FAECALIS & ENTEROCOCCUS CAUCUS
“Protest at the Caucus”
ENTEROCOCCUS FAECALIS & ENTEROCOCCUS CAUCUS
“Protest at the Caucus”
What are the two species of the enterococcus genus?
Enterococcus Faecalis (California) Enterococcus Faecium (Stop the Fees)
Which species of enterococcus is more common?
Enterococcus Faecalis (California)
Which species of enterococcus is more dangerous and why?
Enterococcus Faecium (Stop the Fees), Nosocomial infection resistant to almost every antibiotic we have.
Vancomycin resistant as well (VRE: Vancomysin Resistant Enterococcus)
Both enterococci can grow in mediums of?
Can grow in mediums up to 6.5% sodium chloride
What is enterococcus resistant against?
Bile resistant
What are the main symptoms of enterococcus infections?
DO U <3 T?
U: UTI
<3: Endocarditis
T: Infection of the Biliary Tree
What is the treatment for enterococcus infections?
“Police Line” - Linezolid
“tiger stripes” - Tigacycline
NEISSERIA SPECIES
“Noir Series”
NEISSERIA SPECIES
“Noir Series”
Neisseria is gram positive or gram negative?
Gram negative
neisseria: oxidase positive or negative?
Oxidase positive
What kind of shape does neisseria have?
Dipplicocci (“double hand cuffs”)
What are the agars used for neisseria?
Chocolate agar (its a heated blood agar).
CANT use blood agars since its inhibited by some of lipids/other elements in blood agar unless heated therefore chocolate agar.
VPN agar (Thayer Martin Agar)
What is a VPN agar?
VPN special agar enriched with vancomycin, polymixin, and nystatin
Can be used for Neisseria.
What is another name for VPN agar?
Thayer martin AKA VPN agar
What deficiency causes an increase susceptibility to neisseira species?
MAC complex deficiency due to complex c5-c9 deficiency.
MAC Deficiency unable to form the MAC complex due to complex c5-c9 being inhibited. Patients with c5-c9 deficiency are unable to form MAC complex, leading to increased infections.
MAC = Membrane Attack Complex
What are the virulence factors of Neisseria species?
Virulence Factors
a. Pilli allows attachment to surfaces and display antigenic variation which makes our immune system difficult to target neisseria and prevent any lasting immune response.
b. IgA protease will cleave IGA at its hinge point, facilitates survival along mucosal surfaces.
NEISSEIRA MENINGITIDES
“A SHOCKING DEATH ON CAMPUS”
NEISSEIRA MENINGITIDES
“A SHOCKING DEATH ON CAMPUS”
How does neisseria meningitis spread?
Easily spread in areas with a lot of people, military recruits, college dorms via respiratory droplet
Neissiria meningitis is gram ____________.
Gram negative - Red Hue
What does Neisseiria meningitis ferment?
meningitis ferments maltose and glucose.
Only meningitis ferments maltose
Where does neisseria meningitis first colonize?
Colonizes nasopharynx first, transmitted by respiratory secretions (kissing, sharing drinks, close contacts, sneezing, coughing)
What kind of capsule does neisseria meningitis have?
Polysaccharide capsule that inhibits phagocytosis and its considered its major virulence factor.
How can neisseria meningitis be prevented?
Before SDSU I had to get a shot - the Meningococcal vaccine
It was a vaccine for A,C,D polysaccharide capsules but not B.
Which type of neisseria meningitis accounts for most infections in USA and most developed countries?
Type B since theres no vaccine for it.
Who are more susceptible to neisseria meningitis infection?
Sickle cell and asplenic patients are more susceptible to Neisseria meningitides because it is encapsulated (just like Strep pneumonia!)
What is the physiopathology of neisseria meningitis infection?
N. Meningitides Invades hemotogenously leading to a massive inflammatory response generated by LOS (lipooligiosaccharides) proteins, these are Neisseria’s version of LPS, it grows so much of it that it outgrows the surface area of the bacteria and begins blabbing off.
These blebs of LOS envelope that lead to a massive inflammatory response.
MOST IMPORTANT QUESTION; PATHOGENOSIS:
What does the inflammatory response of neisseria meningitis lead to?
Inflammation leads to leaky capillaries, which leads to characteristic petechial rash leading to thrombocytopenia leading to DIC (Disseminated Intravascular Coagulation)
–> oozing at venopuncture sites, bleeding gums
Capillary leakage can lead to hypovolemia and shock.
Vasoconstriction will go to max to attempt to maintain blood pressure and adrenals can infarct and will contribute to shock (Waterhouse fritter syndrome)
What is the mortality rate of neisseria meningitis infection?
15% mortality rate even with antibiotic treatment.
What is the treatment for neisseria meningitis infection?
3rd generation cephalosporin that can penetrate the blood brain barrier like ceftriaxone
What is Waterhouse fritter syndrome?
Waterhouse fritter syndrome, characterized by hemorrhage of adrenals caused by capillary leak that leads to hypovolemia/shock.
Can be caused by neisseria meningitides.
What is the profilaxis treatment for someone who had close contact?
Rifampin.
Who should be given a profilaxis treatment with someone infected with neisseria mengitis?
Close contact is someone who had more than 8 hours with someone infected during the seven days prior to onset should be given rifampin.
NEISSERIA GONORRHEA
“The Violinists Last Clap”
NEISSERIA GONORRHEA
“The Violinists Last Clap”
How do you get neisseria gonorrhea infection?
Sexually Transmitted Disease
What kind of shape and gram type is neisseria gonorrhea?
Gram Negative Diplococci
what kind of cells are neisseria gonorrhea and what kind of cells do they like to invade?
Facultative intracellular in PMNs
The cells they like to invade are polymorphonuclear lymphocytes (PMNL)
What kind of capsule does neisseria gonorrhea have?
NOT encapsulated
What happens in males when they are affected with neisseria gonorrhea?
Urethritis
Prostatitis
Orchiditis
What happens in females when they are affected with neisseria gonorrhea?
- Pelvic Inflammatory Disease (PID) - can lead to scarring which leads to infertility or ectopic pregnancy.
- Purulent White Charge - which is characteristic of Gonorrhea (can occur to both men and women), generally more thicker and purulent in appearance than chlamydia which tends to be more thin and watery.
- PID can spread to the peritoneum which causes: Fitz Hugh Curtiss syndrome
- May cause polyarthritis in the knee and is asymmetric.
What is Fitz Hugh Curtiss syndrome?
Fitz Hugh Curtiss syndrome: A further complication of the peritoneum is that the infection of the peritoneum can lead to adhesions that form to the capsule of the liver and these long and thin adhesions are referred to as “violin string adhesions”
A joint tap will show purulent synovial fluid that doesnt gram stain, why is that?
Thats because the infection is intracellular.
How can a baby be infected with neisseria gonorrhea?
During delivery if the mother has untreated gonaccocal infection.
What is the first symptom seen in a newborn with neisseria gonorrhea infection?
Gonococcal Conjunctivitis occurs generally during within the first five days.
Chlamydia conjunctivitis occurs after a first week of birth.
What is the TXT of choice for neisseria gonorrhea infection?
Ceftriaxone but if you put that on USMLE its WRONG.
Co infections with Chlamydia are super common so treat for both: Ceftriaxone + Macrolide (such as: azithromycin or doxycycline)
BACILLUS ANTHRACIS + BACILLUS CEREUS
“King Anthra’s Axe”
BACILLUS ANTHRACIS + BACILLUS CEREUS
“King Anthra’s Axe”
What is characteristic symptom of bacillus anthracis infection?
Black Eschar with erythematous ring
Black Eschar: black necrotic cutaneous lesion with a surrounding erythematous ring
What is the capsule of bacillus anthracis and bacillus cereus?
Capsulated with Poly-D Glutamate (capsule is made up of protein instead of the usual polysaccharides)
What is the shape and gram type of bacillus anthracis and bacillus cereus and what disease does it create?
Large Gram positive rods in a chain (unusual to see them in a chain)
Bacillus anthracis, a gram positive bacterium, is the causative agent of anthrax. This organism is capsulogen and toxinogenic.
What does bacillus anthracis and bacillus cereus need to survive?
It is obligate aerobe (can only survive in the presence of oxygen)
How does bacillus anthracis survive?
Bacillus anthracis is a spore forming bacteria allowing them to survive in very poor environments. The spores hibernates without any significant metabolic activity and with a sturdy protective covering its highly resistant to temp/chemicals, so its able to survive an extremely long time in almost any environment.
Think of: 2001 anthrax attacks, also known as Amerithrax.
What are the two important spore forming organisms?
bacillus and clostridium species.
MOST TESTABLE QUESTIONS:
what are the two toxins of bacillus anthracis?
It secretes two toxins which are composed of three proteins: the protective antigen (PA), the lethal factor (LF) and the edema factor (EF).
How does edema factor (EF) work in bacillus anthracis?
EF toxin functions as adenosine cyclase.
It increases cAMP intercellularily this will cause fluid to go extracellular space leading to edema inhibiting host defenses and indirectly preventing phagocytosis
How does lethal factor (LF) work in bacillus anthracis?
LF (lethal Factor), exotoxin that acts as a protease and cleaves MAP Kinase, this is a signal transduction protein that is responsible for cell growth.
This factor (MAP Kinse) will lead to necrosis and black eschar.
What is wool sorter’s disease and what are its symptoms?
pulmonary anthrax, wool sorters disease. Spores can get into wool and hide of animals and persist there. People will inhale the spores when the animal is handled. Then germs in the lungs and cause pulmonary symptoms.
Starts with no specific pulmonary symptoms.
Dry cough.
medianstinal lymph nodes Hemorragic medianstinitis (looks like widen mediastinum on x-rays) Pulmonary Hemorrhage (almost 100% mortality rate)
What is the TXT bacillus anthracis when caught early?
fluoroquinolone (drug of choice)
doxycycline (secondary treatment)
physical characteristics of Bacillus cereus?
Aerobic and spore forming
How can you get sick with Bacillus cereus?
Food poisoning
reheated fried rice and vomitting
CLOSTRIDIUM TETANI
“Rhesus Research Revolution”
CLOSTRIDIUM TETANI
“Rhesus Research Revolution”
Clostridium tetani: gram positive or negative?
gram positive
What kills Clostridium tetani?
Obligate anaerobes (cannot survive in the presence of oxygen)
How do Clostridium tetani survive?
spore forming
How does Clostridium tetani invade our bodies?
Clostridium is found in the dirt and enters the body through a puncture wound.
Rusty nails, barbed wire
Spores found in rusty nails, and in soil
Puncture wound occurs either by nail or barbed wire with tetany spores on it, spores are embedded in the flesh and the organism vegetates and stays at the wound site. It will release tetanus toxin that will cause all the symptoms
What are the symptoms accompanied with Clostridium tetani?
- Relentless muscle contractions: Spastic paralysis leading to rigidity
- Opisthosomas - exaggerated arching of the back
- rhesus sardonicus = evil smile, evil grin
IMPORTANT TEST QUESTION:
Describe pathogenesis of Clostridium tetani.
Tetanus toxin will travel retrograde through the motor axons to the spinal cord.
Tetanus toxin acts as a protease will cleave a protein named “snare” and will inhibit exocytosis of the neurotransmitter into the synapse (GABA and glycine) or Renshaw cells.
2 type of inhibitory neurons, GABA and glycine. If these are inhibited it will result in uncontrolled firing of the motor neurons leading to spastic paralysis.
Renshaw cells will sense over activity of nearby motor neurons and when they sense this activity they will attempt to fire and inhibit the motor neuron. So the GABA and Glycine release from these cells is inhibited leading to spasm
Describe to Clostridium tetani vaccine.
It is a toxoid Vaccine which means toxin conjugated to a protein to increase immunogenicity.
This produces an antibody response to the toxin, not to the organism.
CLOSTRIDIUM BOTULINUM
“Robotulism”
CLOSTRIDIUM BOTULINUM
“Robotulism”
clostridium botulinum: gram type?
Gram positive
How is clostridium botulinum transmitted?
Spore forming.
transmitted by improper canning of food allowing it to flourish in the anaerobic environment producing heat stable toxin.
“a family are presenting with the same neural symptoms” make the dang connection on these kind of questions!!!
what kills clostridium botulinum?
Obligate anaerobe
What symptoms will a patient present with clostridium botulinum infection?
Flaccid paralysis, descending paralysis. Opposite of Guillen barre syndrome. Multiple people is most likely botulism, not Guillen barre.
for example, multiple people who went camping showing these symptoms will be botulinum most likely, NOT Guillen barre.
What kind of paralysis is presented in clostridium botulinum infection?
descending paralysis: diplopia, ptosis
How is the paralysis produced in a clostridium botulinum infection??
to demonstrate the descending paralysis, toxin is unable to cross BBB so only peripheral nervous system is affected.
NOT the central nervous system since it cant cross BBB.
How does the toxin function in a clostridium botulinum infection?
Cleavage of SNARE protein similar to Tetany toxin, only difference is that botulism attacks motor neurons that release Ach, inhibiting motor neuron release leading to flaccid paralysis.
Toxin is a protease that cleaves SNARE proteins.
How do adults get infected with clostridium botulinum infection?
The spores must first germinate in an Anaerobic environment (canned food) and produce the toxin in that environment. Then adults ingest that PREformed toxin.
Ingestion of pre formed antigen from improperly canned foods.
Whats a food that can cause infantile botulism?
Spores in the Honey
Infantile botulism transmitted through ingestion spores in the honey.
How do babies get infected with clostridium botulinum infection?
Ingestion of spores; honey
What syndrome do babies get with clostridium botulinum infection and why is it caused?
Toxin effects similar to babies and cause flaccid paralysis “Floppy Baby Syndrome”
Babies lack robust flora of gut that can out compete Clostridium botulinum will be colonized with spores if they ingest honey. Then they will produce the toxin and have floppy baby syndrome.
Why don’t adults get sick from ingesting infected honey?
clostridium botulinum is a wimp and cant compete with our normal adult flora even though our gut is anaerobic environment, while babies lack this competition.
Whats more common: Adult or Infantile botulism?
Infantile botulism
CLOSTRIDIUM DIFFICILE
“Field Trip to the Chocolate Factory”
CLOSTRIDIUM DIFFICILE
“Field Trip to the Chocolate Factory”
What the street name of clostridium difficile?
King of Diarrhea Bed pan's Worst nightmare C-Dif Chocolate factory pseudomembranous colitis.
What does clostridium difficile for?
Spore forming
What kind of diarrhea is clostridium difficile?
Nosocomial diarrhea (people are affected while hospitalized), spores easily transferred from patient to patient, antibiotics will wipe out normal flora making patients immunocompromised and able to be colonized then create the toxin.
Which is one of the main antibiotics that will cause clostridium difficile?
Clindamycin and poorly washed hands can cause it. Clindamycin is one of the main antibiotics that will cause this.
What are the 2 exotoxins that are produced by clostridium difficile?
Exotoxin A
Exotoxin B
Describe the 2 exotoxins that are produced by clostridium difficile?
Exotoxin A - Binds to the brush border of the intestine and causes inflammation, cell death and watery diarrhea.
“Brush border toxin causing diarrhea”
Exotoxin B - disrupts cytoskeleton integrity by
depolymerizing actin leading to enterocyte death and necrosis. Yellowish grey exudate that forms a pseudomembrane that covers the colonic mucosa. This is why clostridium difficile infection is called a pseudomembranous colitis.
How can you diagnose Clostridium difficile?
PCR: look for the toxin –> Assay to detect TOXIN (not the bacteria that is screened) in stool that will be detected downstream
Clostridium difficile cant survive with?
Obligate anaerobe
Clostridium difficile: Gram type?
Gram positive
What is the treatment for Clostridium difficile?
Oral vancomycin + Metronidazole
Why is oral vancomycin used for treatment?
IV vancomycin wont deliver to lumen of intestine. So its taken orally. Vancomycin also has poor absorption rate orally so its good for side effects minimization.
CLOSTRIDIUM PERFRINGENS
“Private Ringen’s Motorcycle Accident”
CLOSTRIDIUM PERFRINGENS
“Private Ringen’s Motorcycle Accident”
How does clostridium perringens spread?
Spores are formed in dirt and soil
How is one infected with clostridium perringens?
Classic Presentations: (deep military wounds, motorcycle accidents).
Large amounts of flesh are exposed to dirt and dust.
What is clostridium perringens afraid of?
Obligate anaerobe
What are the 2 diseases that clostridium perfingens create?
- clostridial myonecrosis: Causes Gas Gangrene after it enters the wound, gas produced under tissue and has a cracking sound on palpation. Gas is produced as the organism consumes carbohydrates.
- Slow onset diarrhea due to spores needing to reproduce in the gut then create the toxin.
What is the main toxin in clostridial myonecrosis?
This is due to Alpha toxin that effects lipid bilayer and lyses RBC’s which causes hemolysis.
Myonecrosis involves alpha toxin, which is a lecithiinase (phospholipase), which cleaves lecithin which causes damage cell membranes by damaging the lipoproteins.
what the heck is “Double zone of hemolysis”?
Lecithinase can cause red cell hemolysis both in vivo and in vitro.
So when you plate it, it has a zone of hemolysis but its unique that it forms double zone of hemolysis.
What is the TXT for clostridium perfingens?
IV penicillin G
CORYNEBACTERIUM DIPHTHERIAE
“Heart of the Bull Fight”
CORYNEBACTERIUM DIPHTHERIAE
“Heart of the Bull Fight”
Gram type of corynebacterium diphtheriae and its spore type and its shape?
Gram positive, Non-spore forming
Club shape and y or v Shape
What does corynebacterium diphtheriae stain with?
Metachromatic granules that stain with aniline dyes, Metachromatic granules will stain red and the rest of the cell will stain blue.
Describe the 2 exotoxins and its functions of corynebacterium diphtheriae.
Subunit A (active subunit) Toxin causes Ribosylation of Elongation Factor 2 (EF-2), this will inhibit ribosome function inhibiting protein synthesis leading to cell death. This will lead to pseudomembranous exudate that will be found in the oral pharynx.
Subunit B (binding subunit)
Where are the pseudomembranes of corynebacterium diphtheriae found?
pseudomembranes Found in throat and tonsils because the infection is transmitted by respiratory droplets, Can cause airway obstruction and lymphopathy, this will cause bulls neck (thickening of the neck).
What happens when the corynebacterium diphtheriae toxin gets into the blood stream?
It can have systemic effects both on heart and nervous system:
Can cause life threatening myocarditis. Can present arrhythmia and heart block. (lethal effect of diphtheria)
Local paralysis that generally begin in posterior pharynx and can lead to cranial nerve deficits. This is because the corynebacterium diphtheriae toxin will damage the myelin of nerve fibers.
How can you culture test corynebacterium diphtheriae?
Need culturing or toxin assey.
So swab those grayish membranes and plate them on 2 special agars:
plate on Tellurite and Loeflers media
How can you differentiate between toxin and nontoxic strains of corynebacterium diphtheriae?
Eleks test - in-vitro assay on filter paper that has antitoxin on it.
So if toxin binds to it, theres a reaction and the strain is considered toxic.
Which vaccine is used for corynebacterium diphtheriae?
DTaP vaccine is used, often given with tetanus and pertussis vaccine.
Can produce a very powerful IgG response.
Toxoid Vaccine (consists of inactivated exotoxin that of protein)
Which type of patient are most likely to get corynebacterium diphtheriae?
Immigrants since USMLE thinks they dont vaccinate outside USA
What is the treatment for a non vaccinated corynebacterium diphtheriae infection?
Passive immunization (administrating antitoxoid)
LISTERIA MONOCYTOGENES
Santa’s List
LISTERIA MONOCYTOGENES
Santa’s List
Listeria monocytogenes: gram positive or gram negative?
Gram positive
Who are most likely to get sick from a Listeria monocytogenes infection?
Pregnant women are more likely (20 times more) to get listeria than anyone else.
May lead to termination or disease in the newborn
Which test can be done to identify Listeria monocytogenes?
B-hemolytic
Catalase positive
Describe Listeria monocytogenes physically.
Motile and facultative intracellular, tumbling motility extracellular
How does Listeria monocytogenes get around?
Rapidly polymerizes actin along the cell wall allowing it to move quickly in the cell.
Rocket “ Actin Rocket” intracellular movement
can even move from cell to cell
Where does listeria monocytogenes likes to survive and multiply?
Listeria survives and multiplies in near freezing temperatures
What does listeria monocytogenes contaminate?
Can contaminate food items even if they are refrigerated, like milk, cheese
what does listeria monocytogenes do to a new born?
Newborns can get meningitis from the mom, can also get in in adults over 60
Its the 3rd most common cause of meningitis, after Streptococcus B and E. Coli.
What should you tell a pregnant woman about listeria monocytogenes?
Don’t eat soft cheeses.
What is the TXT for listeria monocytogenes?
Ampicillin
PROTEUS MIRABILIS
“The God of the Public restroom”
PROTEUS MIRABILIS
“The God of the Public restroom”
proteus mirabilis: gram type?
Gram negative
What happens to proteus mirabilis when plated?
Demonstrates swarming motility
Is Proteus mirabilis facultative aerobe or facultative anaerobe?
Facultative anaerobe
What diseases can Proteus mirabilis cause?
Kidney Stones
UTI
Tests that can be used for Proteus mirabilis?
Urease positive
H2S positive
What kind of environment gators a struvite stone formation?
Alkaline environment can cause struvite stone formation.
Why is it to know that proteus mirabilis is urease positive?
may form stag horn calculi = kidney stones within pelvis
Ammonia means urease positive, this is what makes the stag horn calculi, to struvite stones causing pain and kidney stones, alkaline formation causes kidney struvite stones.
What kind of odor does a proteus mirabilis infection have?
Fishy odor
What is the TXT for a proteus mirabilis infection?
Sulfonamides
What are struvite stones made of?
Formed of ammonia, magnesium, and phosphate.
YERSINIA ENTEROCOLITICA & PESTIS
“YERSINS PETS”
YERSINIA ENTEROCOLITICA & PESTIS
“YERSINS PETS”
Gram type of Yersinia enterocolitica?
Gram Negative
How does yersinia enterocolitica spreads?
Primarily transmitterd through puppy feces
Contaminated Milk products (like Listeria)
Who are the most common individuals infected with yersinia enterocolitica?
Toddlers, Children (duh!) (since they play with puppies)
What is yersinia enterocolitica resistant to?
Resistant to cold temperatures (like listeria)
Whats so special about yersinia enterocolitica staining?
Stains Heavily on two ends
What is the main virulence factor of yersinia enterocolitica?
Encapsulated virulence factor
What is the main symptom of yersinia enterocolitica?
Bloody diarrhea (invasive)
Invasive systemic effects like fever, intestinal issues, leukocytosis, abscesses, major bowel movements
TEST QUESTION:
What is the main manifestation of yersinia enterocolitica?
Mimics appendicitis
right lower quadrant pain, fever, other classic symptoms of appendicitis like elevated WBC
What is another name for Yersinia Pestis?
Bubonic plague (25 million people dead)
How is Yersinia Pestis spread?
Transmitted through human as incidental host, usually with rats or prairie dogs.
“Rodents” with fleas, then fleas bite humans
What are the symptoms presented in Yersinia Pestis infection?
Forms Buboes (thats why its called Bubonic plague) with swollen tender lymph nodes.
Cause abscesses in organs once it gets in the blood or DIC from endotoxin and neurotoxin
What is the virulence factor of Yersinia Pestis?
Yersinia outer proteins that inhibit macrophages through a type 3 secretion system, inhibiting phagocytosis
What is the TXT for Yersinia Pestis?
?????
What is the prevention for Yersinia Pestis?
Killed vaccine is used to vaccinate
SHIGELLA SONHEI & SHIGELLA DYSENTERIAE
“She-Gorilla’s Circus”
SHIGELLA SONHEI & SHIGELLA DYSENTERIAE
“She-Gorilla’s Circus”
Gram type and indole for shigella?
Gram negative
Indole positive
What are the two main symptoms of shigella?
Gastroenteriitis
Bloody Diahrrea
Which type of agar is used for shigella and how does it look?
Green colonies on Hektoin agar (salmonella makes black colonies)
Special characteristic of shigella?
Immotile
What kind of state is shigella found it that makes it so dangerous?
It is acid stable, needs far fewer microorganisms to cause infection (salmonella needs far more)
What are the two types of shigella?
Shigella sonnei and shigella dysenteriae
Which of the two types of shigella is the most common in united States?
Shigella sonnei
What makes shigella lead to inflammation?
non-lactose, non H2S, LPS(endotoxin) leads to inflammation
What kind of secretion does shigella have?
type III secretion
TEST QUESTION:
describe the pathogenesis of shigella.
Shigella induces M Cells (they are like scouts; they sample things in the lumen and bring back antigens to immune cells on the other side of the intestinal epithelium) in peyers patches to phagocytose them and they escape from the phagolysosome to prior to destruction.
Once in the cytoplasm they will use the host cells actin cytoskeleton to create a tail it can use to propel itself from one cell to the other (like actin rockets in listeria/or like a using M cells as a trojan horse)
Since shigella can survive inside its own cell or in another, what is the name for that?
Facultative intracellular, just like salmonella
TEST QUESTION:
Why does bloody diarrhea occur in shigella?
Once shigella has invaded lymphoid tissue and enterocytes, it Damages tissue and releases cytokines that will inflame the tissues causing a large immune response, clinically we will see fecal blood and leukocytes: bloody diarrhea (underlying inflammatory diarrhea)
TEST QUESTION:
What is the toxin in shigella and how does it work?
Shiga Toxin will bind to the 60s unit of ribosomes and inhibit translation,
TEST QUESTION:
What is hemolytic uremic syndrome (HUS)?
Once shigella invades, it releases a toxin “shigatoxin”, once in blood, shigatoxin enduces endothelial damage, including in the glomerular of kidney. Activates platelets and induces their aggregation, diminishing pool of circulating platelets thus drop in platelets.
The aggregates of platelets protruding out of the endothelium, lyse RBCs they pass by, literally cutting them in half so they look like helmets or shistocytes,
This is pahotgenesis of HUS
Leads to hemolytic uremic syndrome (HUS) in younger children most commonly under 10 years of age.
Progerminal diarrhea following with acute renal failure (glomerular damage).
Form shistocytes
What does shigella use to cause inflammation?
Uses a type 3 secretion system to release inflammatory cytokines
What is the treatment for shigella?
treatment with Macrolides and Fluoroquinolones
ESCHERICHIA COLI & ENTEROHEMORRHAGIC E. COLI & ENTEROTOXIGENIC E. COLI
“E. Cola’s Soda Fountain”
ESCHERICHIA COLI & ENTEROHEMORRHAGIC E. COLI & ENTEROTOXIGENIC E. COLI
“E. Cola’s Soda Fountain”
Gram type of Escherichia coli?
Gram Negative
Which type of agar is used for Escherichia Coli?
Grow pink on MacConkey’s agar
One of the most defining feature of Escherichia Coli?
Lactose fermenter (milk)
What is the main virulence factor of Escherichia coli?
Capsular K antigen
Flagellar H antigen
E coli is also encapsulated with which antigen?
Capsular K antigen
Which test is positive for Escherichia coli?
Catalase positive
oxidase negative
Facultative anaerobic
What happens when Escherichia coli grows on EMB agar?
Eosin methylene blue (EMB, also known as “Levine’s formulation”)
Creates a green sheen
What is the #1 cause of UTI’s?
Escherichia coli (about 80%)
What does Escherichia coli have that allows it to cause UTI?
Fimbriae that will lead to UTI’s #1 cause of UTI’s
What else is Escherichia coli leading cause of?
Gram negative sepsis
What is the virulence factor of Escherichia coli that causes sepsis?
LPS endotoxin (lipopolysaccharide endotoxin) in outer cell membrane
How can Escherichia coli cause neonatal meningitis?
Causes neonatal meningitis only if it has the K antigen
Enterohemorrhagic Escherichia coli (EHEC) most commonly transmitted through what?
Undercooked meat
What is the main symptom of Enterohemorrhagic Escherichia coli (EHEC)?
Bloody diarrhea
Enterohemorrhagic Escherichia coli (EHEC) is the only Escherichia coli that doesn’t do what?
Doesn’t ferment sorbitol
Whats the toxin in Enterohemorrhagic Escherichia coli (EHEC) and what can it cause?
Toxin inhibits ribosomes at the 60s position. Shiga like toxin is the name and can cause hemolytic uretic syndrome (HUS).
Describe the pathogenesis of Enterohemorrhagic Escherichia coli (EHEC) toxin.
Shige like toxin damages endothelial cells of capillaries in the glomerulus. Damaged endothelial lining causes platelets to adhere decreasing platelet count causing thrombocytopenia and these platelets clumps will hemolysis RBC. Little to no fever but mucosal inflammation or invasion.
Which antigen of Enterohemorrhagic Escherichia coli (EHEC) is associated with outbreaks?
O157: H7
Enterohemorrhagic Escherichia coli (EHEC) other name?
Traveler’s diarrhea
Montezuma’s revenge
Whats the most common cause of Enterotoxigenic Escherichia coli (ETEC)?
Recent travel to Mexico where they drank the water.
What are the two toxins Enterotoxigenic Escherichia coli (ETEC) produces?
Heat Labile toxin produces cAMP
Heat Stable toxin produces cGMP
What is the main symptom of Enterotoxigenic Escherichia coli (ETEC)?
Watery Diarrhea
What is the treatment for Escherichia coli?
TMP/SMX or fluoroquinolones
What is the differences between Enterohemorrhagic Escherichia coli (EHEC) and Enterotoxigenic Escherichia coli (ETEC)?
EHEC bloody diarrhea
ETEC watery diarrhea
CAMPYLOBACTER JEJUNI
“Camping Guy and the Bears”
CAMPYLOBACTER JEJUNI
“Camping Guy and the Bears”
Gram type of campylobacter jejuni?
Gram negative
What does campylobacter jejuni look like?
Spiral/curved rod bacilli - enteric
What is the perfect environment for campylobacter jejuni to grow on?
Prefers warm environments around 42 degrees Celsius, thermophile (special incubator)
In which medium does campylobacter jejuni grow on?
Skirrow agar
