Streptococcal

Question 1

Catalase (-) GM (+) bacteria

Answer 1

Streptococcus and Enterococcus

Question 2

Streptococcus characteristics

Answer 2

Gram (+) cocci. Facultative and capnophilic. Fastidious species

Question 3

Hemolysis of Strep

Answer 3

Beta: complete. Alpha: partial. Gamma: none.

Question 4

Color of hemolysis strep

Answer 4

Beta: yellow. Alpha:green. Gamma: white.

Question 5

Group A Strep (GAS)

Answer 5

Only Strep. Pyogenes. Associated with pyogenic infections. Catalase (-). Pronounced beta hemolysis. Requires enriched medium

Question 6

Epidemiology of S. pyogenes

Answer 6

Respiratory droplets. Crowding populations. Deaths usually due to post-infection complications.

Question 7

Seasonal diseases of S. pyogenes

Answer 7

Pharyngitis in winter. Pyoderma in summer

Question 8

Virulence factors in S. pyogenes

Answer 8

Capsule. LTA. M protein. M-like protein. F-protein.

Question 9

Lipoteichoic Acid

Answer 9

Binds to epithelial cells. Accounts for 60% of adhesin

Question 10

M protein

Answer 10

Adhesin. Antiphagocytic. Degrades C3b. Anchored in cell wall/extends to surface with variable sequenece at the distal end. Plasma fibrinogens binds to M-proteins, thus preventing complement activation/opsonization.

Question 11

M-like protein

Answer 11

Binds IgG and IgM. Antiphagocytic

Question 12

F protein

Answer 12

Mediates adherence to epithelial cells and internalization

Question 13

Viral vs bacterial pharyngitis

Answer 13

Viral = 3Cs. Bacterial leads to abcess.

Question 14

Non-suppurrative complications

Answer 14

Rheumatic fever: encapsulated and rich in M proteins.. Acture glomerulonephritis. Typically 1-3 weeks after acute pharyngitis.

Question 15

Scarlet fever

Answer 15

GAS produces erythogenic toxins from lysogenic phi. Diffuse erythematous rash. Strawberry tongue. Rash will disappear in 5-7 days. Signals infaction by harmful GAS.

Question 16

3 toxin types of S. pyrogenic

Answer 16

Exotoxins A, B, C

Question 17

S. impetigo/pyoderma

Answer 17

more common in the summer. Skin colonization preceds clinical infection. Usually in face and legs (minor traumas get infected). S. aureus is main cause, strep pyogenes is second major cause.

Question 18

Cellulitis

Answer 18

Infection involving skin and subQ.

Question 19

Erysipelas

Answer 19

Form of cellulitis, aka butterfly rash.

Question 20

Necrotizing Fascilitis

Answer 20

GAS responsible for 60%. Aka hemolytic strep gangrene. Involves deep fascia.

Question 21

TSS and strep

Answer 21

Likely in pts w/ bacteremic GAS. (Always in NF pts). S. pyrogenic exotoxins act as super antigens. Resembles Staph TSS

Question 22

Paricarditis causes in ARF/RHD

Answer 22

M proteins cause IgG to cross react with heart proteins. Antibiotic prophylaxis is needed.

Question 23

Identification of S. Pyogenes

Answer 23

Beta hemolytic, catalase negative, bacitracin A disc sensitive

Question 24

Only strep that gives a positive PYR test

Answer 24

S. Pyogenes

Question 25

Strep. Agalactiae

Answer 25

Group B strep. Typical in woman urogenital track. Is a risk factor for postpartum sepsis. Babies can aquire it easily

Question 26

Virulence factors of S. Agalactiae

Answer 26

9 capsular polysaccharide types.

Question 27

Diseases of S. Agalactiae

Answer 27

Usually older/immunocompromised pts. UTI during/immediately after pregnancy. Puerperal sepsis**

Question 28

Puerperal sepsis

Answer 28

Serious septicemia during or shortly after childbirth. More rare in developed countries

Question 29

Identification of S. Agalactiae

Answer 29

``` CAMP test (98-100% positive) Bacitracin susceptibility (92% resistant) ```

Question 30

CAMP test

Answer 30

Positive test is hemolysis where the 2 strains intersect (S. Agalactiae and S. Aureus)

Question 31

Viridans Strep

Answer 31

Most produce a green pigment on blood agar. Prevalent in the oral cavity and URT.

Question 32

Important Viridans Strep

Answer 32

``` Strep: Mitis Mutans Salivarius Sanguis ```

Question 33

Disease states of viridans strep

Answer 33

Sub-acute endocarditis, meningitis, pneumonia. (Dental procedures with preexisting cardiac lesions)

Question 34

Major cause of pneumonia in 1880s

Answer 34

S. Pneumoniae

Question 35

Characteristics of S. Pneumoniae

Answer 35

``` Gram positive coccus Diplococci Fastidious (need blood/serum) Growth enhanced bby CO2 Causes alpha hemolysis on blood agar ```

Question 36

Leading cause of bacterial sinusitis/middle ear infections

Answer 36

S. Pneumoniae

Question 37

Virulence of S. Pneumoniae

Answer 37

Can colonized UR with surface adhesins. Produces sIgA protease and pneumolysin (Ply) that kills the ciliated epithelial cells/phagocytes. Lysis causes edema, hemorrhage, bacterial growth.

Question 38

Capsule of S. Pneumoniae

Answer 38

Essential for virulence factor. Inhibits phagocytosis and complement pathways

Question 39

Diseases associated with S. Pneumoniae

Answer 39

Co-inflection with influenza. Pneumonia, Meningitis, Otitis media, sub-acute endocarditis

Question 40

Bacterial Pneumonia

Answer 40

Typically preceded by viral infection. High fever, productive cough, PMNs/lancet shaped diplococci, "rusty" sputum from blood leaks in capillaries. Usually lobar presentation (round in kids).

Question 41

Otitis Media

Answer 41

Infection of middle ear/sinusitis. Leading cause of OM is S. Pneumoniae! Pain and fever very common.

Question 42

3 most common causes of otitis media

Answer 42

S. Pneumoniae Moraxella Catarrhalis Haemophilus Influenzae

Question 43

Bacterial Meningitis and S. Pneumoniae

Answer 43

CSF: purulent, high protein, low glucose. Severe neurological defects in survivors Most severe bacterial meningitis

Question 44

Identification of S. Pneumonia

Answer 44

Catalase negative, bile soluble, optochin sensitive, susceptible to optochin (P disc). Can be tested for in urine. ELISA is 100% in CSF.

Question 45

Enterococcus Characteristics

Answer 45

Gram positive, usually pairs or short chains. Resistant to bile**. High salt, highly antibiotic resistant (Vanco-VRE).

Question 46

Epidemiology of Enterococcus

Answer 46

Nosocomial is very common. Typical in GI and gut.

Question 47

Most common Enterococcus diseases

Answer 47

UTI* mainly nosocomial Peritonitis (after surgery/abdominal trauma) Endocarditis (persistent bacteremia)

Question 48

Identification of Enterococcus

Answer 48

High salt/bile/temp Do not lyse RBCs Positive Pyr test

Question 49

Anaerobic cocci

Answer 49

Part of normal flora of oral, GI tract, Genitourinary tract, skin. Susceptible to common antibiotics. Easily treated if identified as anaerobic cocci.