L29 - high yield

Q: Are Streptococci Gram-positive or Gram-negative?

A: Gram-positive (purple)

Q: What is the morphology and arrangement of Streptococci? (ie how does it look like)

A: Spherical (cocci), arranged in pairs (diplococci) or chains.

Q: Are Streptococci catalase-positive or catalase-negative?

A: Catalase-negative.

______ = Gram-positive cocci + Catalase-negative + Pairs/chains.

Streptococci

Hemolytic _____

Is there hemolysis?

Gamma

There is no hemolysis

Hemolytic _____

Is there hemolysis?

Alpha

Partial hemolysis

Hemolytic _____

Is there hemolysis?

Beta

Complete hemolysis

Q: What is Lancefield classification based on?

A: Antigenic characteristics of C carbohydrates (Lancefield antigens).

Q: What are the five Streptococcal groups listed in the lecture?

A: Group A, Group B, Viridans Group, Group D, and S. pneumoniae.

Q: Which Streptococcus belongs to Lancefield Group A, and what is its hemolysis?

A: Streptococcus pyogenes — Beta hemolytic.

Q: Which Streptococcus belongs to Lancefield Group B, and what is its hemolysis?

A: Streptococcus agalactiae — Beta hemolytic.

Q: Which Streptococcus belongs to Lancefield Group D, and what is its hemolysis?

A: Streptococcus bovis — Alpha or gamma hemolytic.

Q: What is the hemolysis classification of Streptococcus pneumoniae?

A: Alpha hemolytic.

Q: What is the hemolysis classification of Streptococcus mutans?

A: Alpha or gamma hemolytic.

Beta-Hemolytic Streptococci (GAS) belongs to which group?

A

Q: What Lancefield group does Streptococcus pyogenes belong to?

A: Group A (GAS).

“Throw GAS on the fire” = Pyrogenic

Q: What are the two antigenic components of the Streptococcus pyogenes cell wall?

A: C Carbohydrate and M Protein.

________ in Streptococcus pyogenes = Determines its Lancefield Group A classification.

C Carbohydrate

______ = Major virulence factor that inhibits complement activation and protects the organism from phagocytosis.

A: M protein

______ = Oxygen-labile enzyme that destroys RBCs and WBCs and causes antistreptolysin O (ASO) antibodies to develop

Streptolysin O

_______ = Oxygen-stable enzyme that is a principal factor for β-hemolysis but is not antigenic.

Streptolysin S

Q: What diseases are associated with Pyrogenic Exotoxin (Erythrogenic Toxin)?

A: Scarlet fever and streptococcal toxic shock syndrome (TSS), through superantigen activity.

______ = Activates plasminogen to lyse fibrin clots.

Streptokinase

Strep throat with red, swollen tonsils and pharynx = ?

How to treat?

Streptococcal Pharyngitis?

Treatment: Penicillin.

Q: Which GAS skin infection involves the hair follicles?

Folliculitis

Q: Which GAS skin infection causes a pustule on the extremity/face that breaks down after 4–6 days to form a thick crust?

Pyoderma

Q: Which GAS skin infection involves the dermis causing redness and is rarely caused by streptococcus aureus?

Erysipelas

Q: Which GAS infection is known as "flesh-eating streptococcus," and what are its symptoms?

A: Necrotizing Fasciitis; skin becomes red/purple/blue with large blisters.

Q: What causes Scarlet Fever, and what are its characteristic symptoms?

A: Pyrogenic toxin; fever with scarlet-red rash that begins on the trunk/neck and spreads to extremities but spares the face.

Q: What causes Streptococcal Toxic Shock Syndrome (TSS), and what is its outcome?

A: Infection releases toxins into the bloodstream, leading to multi-organ failure.

Q: What causes Rheumatic Fever following GAS infection?

A: Immune response against M protein cross-reacts with heart tissue.

Delayed; Fever, myocarditis, migratory arthritis, rash, and permanent heart valve damage = ?

Rheumatic fever

Q: What treatment is listed for Rheumatic Fever?

A: Prophylactic penicillin therapy.

Delayed; Immune complexes deposit in kidneys and activate complement and PMNs following infection with nephritogenic strains of GAS.

Acute Post-Streptococcal Glomerulonephritis (APSGN)

Q: What is the primary outcome of Acute Post-Streptococcal Glomerulonephritis?

A: Kidney inflammation.

Q: How does clindamycin inhibit GAS virulence factor production?

A: Inhibits bacterial ribosomes, shutting down synthesis of pyrogenic toxin and M protein.

Q: What causes Rheumatic Fever following GAS infection?

A: Immune response against M protein cross-reacts with heart tissue.

Q: What are the symptoms of Rheumatic Fever?

A: Fever, myocarditis, migratory arthritis, rash, and permanent heart valve damage.

Q: What treatment is listed for Rheumatic Fever?

A: Prophylactic penicillin therapy.

Q: What causes Acute Post-Streptococcal Glomerulonephritis (APSGN)?

A: Immune complexes deposit in kidneys and activate complement and PMNs following infection with nephritogenic strains of GAS.

Q: What is the primary outcome of APSGN?

A: Kidney inflammation.

Q: How does clindamycin inhibit GAS virulence factor production?

A: Inhibits bacterial ribosomes, reducing synthesis of pyrogenic toxin and M protein.

Q: What organism is responsible for Group B Streptococcal infections, and what is its hemolysis classification?

A: Streptococcus agalactiae; β-hemolytic.

Q: What infections can Group B Streptococcus cause in pregnant women?

A: Bacteremia and sepsis.

Q: How can newborns acquire Group B Streptococcus?

A: During delivery.

Group B = Baby

Q: What infections can Group B Streptococcus cause in newborns?

A: Neonatal meningitis, pneumonia, and sepsis.

Q: Which three organisms are listed for antibiotic coverage in Group B - S. agalactiae

A: E. coli, Listeria monocytogenes, and Group B Streptococcus.

Q: What type of hemolysis is associated with Viridans Group Streptococci?

Color?

A: Alpha-hemolytic (green in color).

Viri = Verde

Q: Where are Viridans Group Streptococci commonly found?

A: Dental plaque, gingival crevices, tongue, and saliva (>30% of culturable bacteria).

veriDENS = dental

Q: What are the four subgroups of Viridans Group Streptococci?

A: Mitis (S. mitis), Salivarius (S. salivarius), Mutans (S. mutans), and Anginosus (S. anginosus).

Q: Which Viridans Streptococcus is especially associated with dental caries?

A: Streptococcus mutans.

Q: What type of endocarditis is associated with Viridans Streptococci, and how does it occur?

A: Subacute bacterial endocarditis (SBE); bacteria enter the bloodstream and implant on the endocardial surface of the heart (e.g., damaged heart valve).

Q: Which Viridans Streptococci are associated with abscess formation?

A: Anginosus group (S. intermedius, S. constellatus, and S. anginosus).

Q: Where are abscesses caused by the Anginosus group commonly found?

A: Brain or abdominal organs.

Q: What should be suspected if S. intermedius is found in the bloodstream?

A: A hidden abscess in an organ.

Q: What are the two subgroups of Group D Streptococci?

A: Enterococci and Non-Enterococci.

Q: Which bacteria belong to the Enterococci subgroup of Group D?

A: Enterococcus faecalis and E. faecium.

Q: Which bacteria belong to the Non-Enterococci subgroup of Group D?

A: Streptococcus bovis and S. equinus.

Q: Where are Group D Streptococci commonly found?

A: Digestive tract.

When you see Group D = Digestive tract

Q: What type of hemolysis is associated with Enterococci?

A: α-hemolytic or γ-hemolytic.

Q: What infections are commonly caused by Enterococci?

A: UTIs, biliary tract infections, bacteremia, and subacute bacterial endocarditis (SBE).

Q: What antibiotics does the slide identify Enterococci as resistant to?

A: Ampicillin, aminoglycosides, and vancomycin (VRE).

Q: What is the mechanism of vancomycin resistance in Enterococci (VRE)?

A: The acquired vanA gene encodes proteins that modify the peptidoglycan terminus from D-alanine–D-alanine to D-alanine–D-lactate, resulting in low affinity for vancomycin.

Q: What are the growth characteristics of Non-Enterococci?

A: Grow in 40% bile but not in 6.5% NaCl.

Q: Where are Non-Enterococci commonly found, and what diseases do they cause?

A: GI tract; cause similar diseases to Enterococci.

Q: What cancer is strongly associated with Streptococcus bovis infection?

A: Colon cancer.

BOVIS in the BLOOD, CANCER in the BOWEL.

Q: What are the major infections caused by Streptococcus pneumoniae?

A: Bacterial pneumonia and meningitis (adults), and otitis media (children).

Q: Does Streptococcus pneumoniae possess a Lancefield antigen?

A: No Lancefield antigen.

Q: What is the morphology and Gram stain of Streptococcus pneumoniae?

A: Lancet-shaped, Gram-positive cocci arranged in pairs (diplococci).

Q: What is the major virulence factor of Streptococcus pneumoniae?

A: Antigenic polysaccharide capsule.

Q: What is the function of the capsule in S. pneumoniae?

A: Impedes phagocytosis (has 91 distinct antigenic types)

Q: What is the function of Pneumolysin in S. pneumoniae?

A: Cytotoxin.

Q: What is the function of Hydrogen Peroxide in S. pneumoniae?

A: Hemolysin.

Q: What is the function of IgA1 Protease in S. pneumoniae?

A: Cleaves IgA1.

Q: What is the function of Neuraminidase in S. pneumoniae?

A: Cleaves terminal sialic acid, exposing glycoconjugates for adhesion.

Q: What are the adhesins of S. pneumoniae?

A: Teichoic acids and CbpA.

Q: How can S. pneumoniae be distinguished from Viridans Streptococci using optochin?

A: Both are α-hemolytic, but S. pneumoniae is optochin sensitive (growth inhibited), whereas Viridans Streptococci are optochin resistant.

Optochin Sensitivity: S. pneumoniae and S. viridans are _____-hemolytic

• Growth of S. pneumoniae is _______ when placed in optochin disc, whereas S. viridans is resistant.

alpha; inhibited

Q: What happens during the Quellung Reaction?

A: A bacterial smear is mixed with antiserum and methylene blue, causing the capsule to swell (rapid identification).

Q: What is the result of the bile solubility test for S. pneumoniae?

A: Positive; S. pneumoniae is lysed by bile acids.

Q: What happens in the alveoli during Pneumococcal Pneumonia?

A: Alveoli fill with WBC pus, bacteria, and exudate.

Q: What are the characteristic symptoms of Pneumococcal Pneumonia?

A: Shaking chills, high fevers, chest pain, shortness of breath, and yellow-green phlegm.

Q: What disease does S. pneumoniae cause in children involving the middle ear?

A: Otitis Media (middle ear infection).

Q: What are the characteristic symptoms of Sinusitis caused by S. pneumoniae?

A: Nasal congestion, drainage, facial pain/pressure, and decreased sense of smell.

Q: What is the characteristic sign of Bacterial Meningitis caused by S. pneumoniae in adults?

A: Nuchal rigidity (stiff neck).

Q: What antibiotics are certain strains of S. pneumoniae developing resistance to?

A: Penicillin, erythromycin, trimethoprim/sulfamethoxazole, and chloramphenicol.

Q: What is the treatment for S. pneumoniae with intermediate penicillin resistance?

A: High-dose penicillin and cephalosporins.

Q: What antibiotic is recommended for highly penicillin-resistant strains of S. pneumoniae?

Vancomycin

What species is associated with Group A: Beta Hemolytic Strep (GAS)

S. pyogenes

Metabolsim effect of Group A: B hemolytic strep (GAS)

Catalase -ive, Beta-hemolytic

Virulence factor associated with Group A: Beta Hemolytic Strep (GAS)

M-protein

What toxins are associated with Group A: Beta Hemolytic Strep (GAS)

Pyrogenic, TSS toxin

Diseases associated with Group A: Beta Hemolytic Strep (GAS) (S. pyogenes)

Pharyngitis

Skin infections: Folliculitis

Cellulitis

Impetigo

Necro. Fascitis

Scarlet fever

TSS (Toxic shock syn)

Rheum. Fever

Glomerulonephritis

treatment of Group A: Beta Hemolytic Strep (GAS)

Penicillin G, Pen. V, Erythromycin, 1st generation Cephalosporins, Azithromycin

What enzyme virulence factors are associated with group A?

• Streptolysin O - oxygen labile; destroys RBC & WBC; infection causes anti-streptolysin (ASO) 

• Streptolysin S - oxygen stable; principal factor Beta-hemolysis; not antigenic

• Pyrogenic Exotoxin - causes scarlet fever; superantigens that cause streptococcal TSS 

• Streptokinase - activates plasminogen to lyse fibrin clots

What species is associated with Group B?

S. agalactiae

Metabolism effect of group b?

Catalase -ive, Beta-hemolytic

Diseases assocated with group B (S. agalactiae)?

Neonatal meningitis

Neonatal pneumoniae

Neonatal Sepsis

Pregnant women: bacteremia & sepsis

Treatment for group B?

Penicillin G

Antibiotics against E. coli, Listeria monocytogenes, and Group B Streptococcus (common cause neonatal meningitis)