L2 - Staph vs Strep Flashcards
There are three Staphylococcus Species.
What are they?
Staph Aureus
Staph Epidermidis
Staph Saprophyticus
Are all 3 staph species gram-positive?
yes, gram +
Staph Epidermidis
what kind of pathogen is this?
opportunistic
nosocomial infections
Staph Saprophyticus
what kind of pathogen is this?
UTIs in women
There are three Streptococcus species, what are they?
Staph Pyogenes Staph Pneumoniae Group B streptococci ( S. agalactiae)
Are all the strep species gram +?
YES!
Staphylococci occur in what kind of way?
Single and in pairs, mostly in clusters!
Staphylococci. Are the Catalase + or Catalase -?
Catalase +
Streptococci occur in what kind of way?
pairs, short and long chains!
Streptococci. Catalase + or Catalase -?
Catalase -
How to differentiate between the 3 Staph species?
if they have coagulase activity.
Which Staph specie is + for Coagulase activity?
Staph Aureus
Which staph species are Coagulase -?
Staph. Epidermidis Staph Saprophyticus
Coagulase?
ability to coagulate plasma. Fibrinogen to fibrin ( insoluble)
Virulence Factors in Staph Aureus
Hemolysins Leukocidin Protein A Coagulase
Staph Aureus Invasive disease traits:
Alpha & leukocidin lyse cells by disrupting cell membrane integertiy- result in the tissue destruction and abcess formation seen with invasive staphlococcal disease. Protein A- binds Fc of IgG molecule ( prevents phagocytosis) Teichoic Acids- binds fibronectin on mucosal surfaces
Staph Toxins
Alpha Toxin - Lyses cells by forming pores in epithelium Enterotoxins - food poisoning toxic shock syndrome toxin 1 - causes hypotensive shock, rash, and cytokine elaboration Exofoliative toxin -staphylococcus scalding skin syndrome (SSSS) Panton-Valentine Leukocidin PVL - necrotic lesions involving skin and mucosa
PVL and Staph Aureus
-PVL and SA infections are associated with higher incidence of sepsis, high fever, leukopenia, hemoptysis, pleural effusion, and mortality. -Severe soft tissue and bone infection -necrotizing pneumonia -pvl genes are being found in increasing prevalence in community acquired MRSA
MRSA creates ?
PVL
Clinical Syndromes of Staph Aureus
Skin infections - folliculitis -furuncles (boils) -wounds -impetigo
Clinical syndromes of Staph Aureus
-Bacteremia -Endocarditis -Pneumonia -Osteomyelitis -Septic Arthritis
Staph Aureus Virulence Factors
Toxin-mediated disease - exfoliatin- toxin that causes sloughing of the outermost layer of the skin (SSSS) -TSST-1* - toxin which causes the hypotension, rash, desqamation and production of cytokines (TSS) Enterotoxins- acid and heat resistant toxins causes food poisoning occurs 1-8 hours after toxin ingestion. *super antigen
Epidemioglogy of Staph Aurus
-Can be carried on skin, urogenital tract -resist drying spread by contact or formites ( towels)
Laboratory Diagnosis of Staphylocci
direct gram stain and culture culture on BAP ( blood agar plate) or mannitol salt sugar usually strong BETA hemolytic ( staph aureus) non hemolytic ( staph epidermidis) Catalase test + Coagulase + Gram +
Staph infections- treatment
Oxacillin, cephalosporin, or vancomycin (MRSA) drainage of lesions plasmid encoded beta-lacatamases common
Streptococcus pyogenes, which lancefield group? Hemolytic ?
Beta-Hemolytic. Lancefield group A.
Streptoccus agalactiae, which lancefiels group? Hemolytic?
Beta-Hemolytic. Lancefield group B.
Streptococcus pneumoniae. which hemolytic?
Alpha Hemolytic.
Enterococcus Species (Formerly Lancefield group ?)
Group D. Gamma-Hemolytic.
Strep Pneumoniae
Pneumonia, sinusitis, otitis media, meningitis, bactermia.
Strep Pyogenes
Pharyngitis, scarlet fever, toxic shock, erysipleas, pyoderma, rheumatic fever, glomerulonephritis.
Strep Agalactiae
neonatal infections ( meningitis, pneumonial, bactermia, postpartum sepsis.)
Viridans group
Bacteremia, endocarditis, dental
Streptococci general traits
pairs, short and long chains Catalase -
Streptococci clinical presentation
Pyogenic- pus, oral, enteric
Strep Pyogenes
Pharynigitis, scarlet fever, toxic shock Short chains in clinical samples Longer chains on liquid media Beta Hemolytic
As a microbiologist, you have completed a gram stain and see that the bacteria in question is Gram + cocci but you cannot differentiate if they are in chains or clusters. What test could you perform to help you determine if it is staph or strep?
Catalase test
Acid-fast staining
Aerobe testing
Antibiotic resistance testing
Catalase test
You decide to go on a picnic with some friends and pack sandwiches. The sandwiches have been sitting out for a bit but you make the call that they should be fine. 2 hours later everyone starts to feel sick and vomit. What S. Aureus toxin is at fault?
Alpha toxin
exfoliative toxin
PVL
TSST
enterotoxin
enterotoxin
Streptococcus Pyogenes Virulence Factor
Streptokinase
streptolysins
Erythrogenic toxin- associated with rash of scarlet fever, superantigen
Exotoxin A- associated with toxic shock
Exotoxin B- associated with necrotiing fasciitis
Capsule
M Protein
M-Protein : Steptococcus pyogenes
resist phagocytosis
binds factor H
mimics host antigens
Molecular mimicry
Protein F- Streptococcus Pyogenes
Binds Fribronectin
Protein G : Streptococcus Pyogenes
Binds antibodies via Fc region
C-polysaccharide : Streptococcus pyogenes
antigeneic, cross reactive with host components
Peptidoglycan : Streptococcus pyogenes
Induces chronic inflammation
Pathogenesis of respiratory Infections : streptococcus pyogenes
inhibits phagocytosis and complement
Diseases group A strep : Streptococcus Pyogenes: Suppurative diseases
- Pharyngitis
- Scarlet Fever
- Streptococcal Toxic Shock
- Cellulitis
- Fasciitis
Disease group A : Non-Suppurative disease : Streptococcus pyogenes
- Rhemutatic fever
- Glomerulonephritis
Streptococcus Pyogenes : Clinical Presentation
- Strep Throat
- fever, malaise, headache
- pharyngitis develops 2 to 4 days after exposure
Streptococcus Pyogenes: Scarlet Fever
Infecting strains has a lysogenic phage
encoding a exotoxin
exotoxing is spread through circulatory system
diffuse rash over the body and fever
-strawberry tonuge
Skin infections caused by S. Pyogenes
- impetigo ( may involve S. Aureus)
- Cellulitis
- Necrotizing fasciitis ( flesh EATING)
Non-suppurative diseases : Strep Pyogenes
Acute Glomerulonephritis
- edema, hypertension, proteinuria, hematuria ( blood and protein in urine)
- involves deposition of antigen-antibody complexes (type 3 hypersensitivity)
- occurs 10 days following infection
Non suppurative diseases : Strep Pyogenes
Rhematic fever
- inflammatory response to streptococcal antigens
- fever,carditis, polyarthitiris
- patients 5-15, approcimately 3 weeks after pharyngitis
- can last 2-3 months
- no diagnostic test
- chronic progresssive heart damage
- prophylaxis prevent reoccurence
Diagnosis of group A : Steptococcus Pyogenes
- Bacitracin sensitive
- rapid strep test (antigen detection)
- serologic tests ( anti-strepolysis o titers)
treatment of group A strep pyogenes
Treatment : Penicillin
Pertinient Features of Group A Strep Pyogenes
Indigenous microflora
person to person spread, fomites
Adhesions
- Lipteichoic acid (LTA)
- interact with host fibronectin
Spread
- proteases, hyaluronidase, DNAse and streptokinase
- Resistance to phagocytosis
- M protein
- Hyaluronic acid capsule
- Tissue Damage
- Exotoxins
Group B Streptococcus :
Streptococcus Agalactiae
Strep Agalactiae
Puerperal Sepsis, Septicemia, Pneumonia, newborn meningitis
Larger than group A, and beta-hemolysis zone is smaller
Group B Strep Agalactiae
Outermost- capsule
cells wall
- glucosamine, rhamnose, galactose
pathogenesis of group B strep agalactiae
requires complement
-enzymes- deozyribonucleases, hyalronidase, nerumoinidase,
location- upper resp.
lower GI
vagina
Streptococcus Pneumoniae
cells are lancet shaped or in pairs or shoft chains
Alpha- hemolytic
inhabitiant of the thorat and nasopharynx of healthy individuals
gram +
Normal Flora is found in all but?
- Genitourniary
- Oral Cavity
- Optic Cavity
- Nares
-optic cavity
Fungi are not part of our microbiome?
F. They are!
To enhance the growth of the good bacteria in your gut microbiome, what would you eat?
- yogurt
- fiber
- probiotic pills
- popsicles
-fiber bc its a prebiotic!
The main cause of dysbiosis is?
- Diet Change
- Prebiotics
- Probiotics
- Antibiotics
-Anitibiotics
Clostidium Species would classify as :
-good bacteria
or bad bacteria?
efficient or poor harvesters?
Bad bacteria- efficient harvesters
