Staph and Strep Flashcards
Describe the physical structure of Staphylococci?
G+ cocci in clusters
What is the catalase sensitivity of Staphylococci?
Catalase +
How does Staphylococci feel about salt?
Tolerant, grow up to 9%
What two factors are used to differentiate Staphylococci?
Hemolysis
Coagulase
Clinical presentations of Staphylococcus Aureus caused mainly by bacterial growth?
Fununcles
Folliculitis
Non-bullous impetigo
Bacteremia/Wound Infections
How are furuncles walled off?
Coagulase
What is Staphylococcus Aureus folliculitis associated with?
Shaving
Contact with Fomite
Complication of Acne
Primary cause of acne?
Proprionibacterium acnes
What is non-bullus impetigo?
Infection is the superficial epidermis
Most Common Bacterial Skin Disease
Crusted Blisters
Who usually gets non-bullus impetigo?
Children and Teens
Two most frequent causes of non-bullus impetigo?
Staphylococcus Aureus
Strep – Group A
Staphylococcus Aureus bacteremis/wound infection is a major concern in…
Surgical wounds
Esp. deep incisions that go into muscle, or organ space
Clinical presentations of Staphylococcus Aureus typically associated with exotoxin release.
Bullous exfoliation
Bullous impetigo
What is Bullous exfoliation?
Staphylococcal scalded skin syndrome
Intraepidermal splitting and peeling of top layers
Who gets bullous exfoliation?
Mostly Children
Prognosis of Staphylococcus Aureus bullous exfoliation in kids? adults?
Kids – Good Prognosis
Adults – Bad – Indicates Bacteremia
What is Staphylococcus Aureus bullous impetigo?
Fluid filled blisters within the epidermis
Painful
Who gets Staphylococcus Aureus bullous impetigo?
Kids under 2 years old
Cause of Staphylococcus Aureus bullous impetigo?
Exfoliative Toxin
What is a Staphylococcus Aureus bully?
A fluid filled blister in the epidermis
Clinical presentation of Toxic Shock Syndrome?
Abrupt onset fever
Rash with desquamination
Hypotension
Multisystem, DIC
Two types of Toxic Shock Syndrome?
Menstrual and Nonmen (M&F-often nosocomial)
Cause of Toxic Shock Syndrome?
TSST triggers immune rxn
Clinical presentation of Staphylococcus Aureus food poisoning?
Violent Nausea, Vomiting, Diarrhea
NO Fever
VERY quick (gone within 24)
Food poisoning in which you see more vomiting than diarrhea? (3)
B cereus
Staphylococcus Aureus
Norovirus
Why is there a different presentation of Toxic Shock and Food Poisoning.
You have lots of Tregs in the gut and few in the bloodstream
Typical clinical presentation of Staphylococcus epidermis?
Nosocomial Infections, esp. in surgery
Biofilm Formation
Typical clinical presentation of Staphylococcus saprophyticus?
UTI in young women
Has specific adhesion for UT epithelia
Menstrual TSS is associated with…
Retained tampons
Why can’t you eradicate Staphylococcus?
Its a part of the normal flora
Why is Staphylococcus difficult to treat?
Rapid multi-drug resistance development (ex. MRSA)
Four antigens associated with Staphylococcus?
PG
Teichoic Acids
Protein A
Iron Binding Proteins
What does Protein A do?
Binds to Fc part of Ab
Allows bacteria to present “self” antigens to body
Toxins associated with Staphylococcus? (6)
Coagulase Hyaluronidase/Streptokinase Hemolysins Exfoliative Toxin TSST-1 Enterotoxins
What does coagulase do?
Walls off infection
What does hyaluronidase/strepto do?
Tissue Invasion
Name three types of hemolysins (and targets)
alpha toxin (RBCs, plat) beta toxin (sphingomyelin) Leukocidin (WBC)
What is PVL?
Panton-Valentine Leukocidin
Pore forming toxin associated with MRSA, esp. USA300
What does Exfoliative toxin do?
Cleaves N Terminal of desmoglein-1 cell-cell adhesin
scalded skin syndrome, bullous impetigo
What is TSST-1?
A superantigen
Induces T cells to produce IL1, TNF
What are the two superantigens discussed with Staphylococcus?
TSST-1
Enterotoxins (Food Poisoning)
How are superantigen toxins spread from bacteria to bacteria?
On PAIs via transduction.
Horiz Gene transfer
What steps have been made to improve hospital MRSA control?
Better ahnd hygiene
Targeting catheter infections
MRSA-specific detection and decolonization
Give an example about how docolonization might pan out?
Chlorhexidine washes
How are recurrent Staphylococcus furuncles treated?
drainage and tetracycline
Preferred antibiotics for Staphylococcus?
nafcillin
oxacillin
cefazolin
How is MRSA typically treated?
SxT Clindamycin Doxy Linezolid IF SEVERE -- Vanco
How had MRSA treatment be optimized?
Susceptibility Testing
Staphylococcus antiobiotic resistance spreads via ___ plasmids.
R-
Describe the physical structure of Streptococci and enterococci.
G+ Cocci
May be oval in chains/Pains
Describe the oxgen requirements of Streptococci
Facultative, but prefer 5-10% CO2
Streptococci capsules are made with…
Group A – Hyaluronic Acid
Polysaccharide
Classification of Streptococci is based on…
Hemolysis
Serotyping
Biochemistry
Colonization pattern
Difference between alpha and beta hemolysis?
alpha doesn’t steal the iron
beta does steal the iron
How does Lancefield serotyping split up Streptococci?
Specific amino-sugar and teichoic acid cell wall antigens
A-H, K-U
Biochemistry informaiton you would look for in classifying Streptococci?
Antibiotic resistance, NaCl tolerance, Bile-esculin
Clinical presentation of Group A Streptococci Pyogenes?
Invasive Infections
Group A Streptococci Pyogenes is which kind of hemolytic?
Beta
Group A Streptococci Pyogenes is sensitive to what antibiotic?
Bacitracin
Examples of Group A Streptococci Pyogenes invasive infections (8)
Human Erysipelas Puerpeual Fever Surgical Sepsis Scarlet Fever Streptococcal Toxic Shock Like Syndrome Necrotizing Fasciitis Bacteremia Penumonia (more serious than pneumococcal)
What is Puerpeual Fever?
Strep of the uterus
Symptoms of Scarlett Fever?
Strep bacteremia
Characteristic Diffuse upper body
Rash, Fever, “Strawberry tongue”
Usual initial presentation of Group A Streptococci Pyogenes Scarlet Fever?
Scarlet Fever
What is necrotizing Fasciitis?
Deep cellulitis that spreads through sub-Q tissue into and through the deep fascia
Can be staph or strep
Why can’t you culture fluid from a Group A Streptococci Pyogenes fluid bully.
Its the toxin, not the bacteria
Examples of Group A Streptococci Pyogenes local infections (8)
Pharyngitis
Impetigo
Symptoms commonly seen in Group A Streptococci Pyogenes pharyngitis.
Fever, Ant. Cerv. Lymphadenopathy, Tonsil Exudate
NO COUGH
Tonsilar Pus and Palletal Petachiae
Describe the clinical presentation of Group A Streptococci Pyogenes impetigo.
Crusty, Purulent Blisters
Esp. on Face
ALWAYS non-bullous
What do you need to look out for in the weeks following Group A Streptococci Pyogenes? Two manifestations?
Autoimmune responses
Acute Rheumatic Fever
Acute Glomerulonephritis
What symptom might you look for in Acute Rheumatic Fever
Heart Valve Damage following Strep Throat
What might you expect to see in the labs of a person with acute glomerular nephritis.
Blood and Protein in Urine
Reservoirs of Group A Streptococci Pyogenes?
Only Humans (10-20% carrier rate)
Epidemiology of strep throat…
How does it spread, when does it spread, who does it spread to
Nasal Droplets + Contact
Winter
Esp. 6-13 years
Epidemiology of Impetigo…
How does it spread, when does it spread, who does it spread to
Contact, Contiguity, Fomites (Sheets, Pillows)
Summer/Early Fall
Age Peak in Preschool Children
Epidemiology of Rheumatic fever…
How does it occur, when does it spread, who does it spread to
Usually 1-4 weeks after disseminated strep
Pathogenesis of (How does it spread, when does it spread, who does it spread to) involved what toxins, Vir Factors (8)
M Protein Hyaluronic Acid Capsule C Substance C5a peptidase Streptokinase Streptodornase Exotoxin Hemolysins
Effect of M protein?
Cause secretion of heart-reactive antibodies
Effect of hyaluronic acid capsule?
Mimics host, so antiphagocytic
What si C substance?
A Capsular polysaccharide that enhances invasiveness
What is C5A peptidase
Antiphagocytic (anti-complement)
What does streptokinase do?
Dissolves fibrin clots
What does streptodornase do?
DNAse, high viscosity pus from nucleoprotein
What is hyaluronidase?
Spreading Factor
Two types of hemolysins seen in Group A Streptococci Pyogenes?
Streptolysin O – O2 Sensitive
Streptolysin S – not O2 Sensitive
How is Group A Streptococci Pyogenes controlled
Prevent spread – pasteurize milk, isolate carriers from patients
Treat acute infections early
How are Group A Streptococci Pyogenes treated?
All sensitive to PenG
If necessary, anti-inflammatories, rest
Species that makes up Group B Strep
S agalactiae
Group B strep is ____ hemolytic
It is cAMP _____
and Bacitracin _______
Beta
Positive
Resistant
Clinical presentation of Group B strep is?
Neonatal Sepsis/Pneumonia
Neonatal Meningitis
Resp. Distress Syndrome
Bacteremia
Who gets Group B strep?
Infants, IC, Elderly
How is Group B strep usually spread?
Spread from infected mothers to baby in delivery
How is Group B strep controlled?
Screen Before Delivery
If +, 3rd gen Ceph or Amp+Strep
Give baby prophylactics
Group D strep consist of….
Enterococci and S bovis
Group D strep are ______ hemolytic
Mostly Non-
Sometimes alpha
Clinical presentation of Group D strep?
Nosocomial Infections
Bacteremia
Endocarditis
UTI
How is Group D strep typically transferred?
Hands of hospital workers
Portal of entry — GI tract/bacteremia from colon lesions
How is Group D strep controlled? (or not controlled)
Enterococci resistant to beta-lactams, SxT
Treat SYNERGISTICALLY with penicillin and aminoglycoside
Why might you consider/not consider using vanco to treat enterococcus?
It should work, but there is a high frequency of vancomycin resistance in the US
Infective endocarditis is typically caused by…
Staphylococci and streptococci
Oral (Viridans) Streptococci is ___ hemolytic
optochin _________
Alpha
Resistant
Most common clinical manifestation of Oral (Viridans) Streptococci?
Sub-acute bacterial endocarditis
(esp after tooth surgery)
Heart murmur, Weaknes, Anemia, Embolism
Prognosis for an untreated Oral (Viridans) Streptococci infection?
100% fatal.
Who would you expect to get Oral (Viridans) Streptococci infection?
Someone who has recently had a dental procedure
How is Oral (Viridans) Streptococci treated?
Long term, High Dose antibiotic
How is Oral (Viridans) Streptococci controlled?
Prophylactic antibiotics before/after oral surgery
Strep pneumoniae is ___ hemolytic and optochin _____
Alpha
Sensitive
Strep pneumoniae physical structure…
Diplococci with large polysaccharide capsule
What is a quellung reaction?
Add polyvalent antiserum against capsule + Sputum
If Strep pneumoniae present, capsule will swell
Visualize by negative stain
Clinical presentation of Strep pneumoniae?
Lobar Pneumonia with Fever, Chills, Sharp Pain
Mental Confusion
Increased Leukocytes
May spread to Middle ear (#2 otitis media)
May spread to meninges (#1 for middle age adults)
Describe lobar pneumonia.
Consolidation of one+ lobes
Bronchi often open
Describe bronchopneumonia
Patchy, Peribronchial Thickening
Consolidation of Alveoli
Describe Interstitial pneumonia
Inflammation and edema of interstitial tissue of the lung
Fibrosis
Three risk factors associated with Strep pneumoniae?
Mucus accumulation
Alcohol/Drug Use
General Debility (Flu, anemia, COPD)
Pathogenesis of Strep pneumoniae?
Colonization of tissues
Polysac. capsule and debilitated host are critical
IgA Protease
How is Strep pneumoniae controlled?
Vaccines available to prevent pneumococcal disease
