Bacteria

Question 1

Characteristics: gram stain, species, common infections, treatment

Answer 1

G+ cocci that inhabits intestinal tract

2 Species: Faecalis/Faecium

Grows in mediums up to 6.5% sodium chloride

Generally causes nosocomial infections that are resistant to most known antibiotics including vancomycin

Generally treat with Linezolid or Tigecycline

Question 2

Name Pathogen

Answer 2

Enterococcus

Question 3

Name pathogens represented and common features

Answer 3

Strep Pneumoniae and Strep Viridans

Both are Alpha-hemolytic

Question 4

S. Agalactiae Illnesses

Answer 4

Known for serious infections of the newborn such as meningitis, sepsis, and pneumonia

All pregnant women are cultured at 35 weeks for presence of Group B strep infection and treated with intrapartum penicillin if positive.

Question 5

Name the pathogen, describe characteristics including gram stain, specific tests, +/- capsule, hemolysis and other features

Answer 5

G+ positive cocci, + hippurate test, polysaccharide capsule, +CAMP Test, Beta-hemolytic, Bacitracin resistant

Question 6

G+ cocci, catalase +, urease +, coagulase -, novobiocin sensitive

Answer 6

Staphylococcus Epidermidis

Question 7

Common pathogen that infects artificial joints, implanted hardware (e.g. artificial heart valves), indwelling catheters

Answer 7

S. Epidermidis

Question 8

Treatment

Answer 8

Due to resistance to many abx, requires Vancomycin

Question 9

S. Pneumoniae

Pneumonia

Answer 9

Affects lower lobes, typically presents with rust colored sputum

Primary cause of CAP

Question 10

S. Pneumoniae

IgA Protease

Answer 10

Cleaves IgA which allows it to colonize and invade mucosal tissues

Question 11

S. Pneumoniae

Treatment

Answer 11

Susceptible to Erythromycin or Ceftriaxone

Also preventable with pneumonvax vaccines which bind polysaccharide capsule to a protein

Question 12

S. Pneumoniae

Population most at risk of infection

Answer 12

Any individual who has had a splenectomy

Particularly high risk for sickle cell patients due to auto-splenectomy

Question 13

S. Pneumoniae

General Characteristics and Virulence Factors

Answer 13

G+ lancet shaped diplococci that are optochin sensitive and bile soluble

Virulence: IgA Protease

Question 14

S. Pyogenes

M Protein

Answer 14

Interferes with opsonization

Very antigenic and can cause molecular mimicry

Question 15

S. Pyogenes

Streptolysin O

Answer 15

Lyses RBCs

Generates ASO antibodies

Question 16

Diseases caused by Streptococcal Pyrogenic Exotoxin

Answer 16

Scarlet Fever

Toxic Shock Like Syndrome

Necrotizing Fasciitis

Question 17

Rheumatic Fever Symptoms and Cause

Answer 17

Symptoms: after pharyngitis infection clears patient develops endocarditis, patient experiences type II hypersensitivity reaction:

J: Joint pain (polyarthritis)

O: myocarditis and pericarditis

N: Nodules

E: Erythema marginatum

S: Sydenham’s chorea

Generally causes mitral valve stenosis in later years.

Caused by molecular mimicry to M protein found in cell wall of S. Pyogenes

Question 18

Post-streptococcal Glomerulonephritis

Answer 18

Type III Hypersensitivity Reaction

Circulating Ab-Ag complexes deposit in glomerulus

Sx: Cola-colored urine and facial swelling that occur 2 weeks after pharyngitis, impetigo, cellulitis, or erysipela infection

Can still occur despite antibiotic treatment of S. pyogenes infection

Question 19

S. Pyogenes

Scarlet Fever Symptoms

Answer 19

Reddening or swelling of the tongue (strawberry tongue)

Pharyngitis - red, erythematous inflamed throat

Widespread rash that excludes the face

Question 20

G+, catalase+, Urease+, Coagulase -, novobiocin resistant

Answer 20

Staphylococcus Saprophyticus

Question 21

Common cause of UTIs in sexually active women

Answer 21

Staphylococcus Saprophyticus

Question 22

S. Viridans

Endocarditis Pathogenesis

Answer 22

Occurs in damaged heart valves only

Generally patient has teeth cleaned leading to a transient bacteremia

Adheres to fibrin platelet aggregates on damaged heart valves by synthesizing dextrans from glucose

Question 23

S. Viridans

General Characteristics

Answer 23

G+ cocci, alpha-hemolytic, unencapsulated, optochin resistant, bile insoluble

Question 24

What two Staphylococcus bacteria are coagulase -?

Question 25

What bacteria are in this image?

Answer 25

Staphylococcus Epidermidis and Saprophyticus

Question 26

# S. Aureus What is TSST?

Answer 26

A super toxin found in S. aureus that has nonspecific binding to MHC class II positive T Cell receptors Leads to a cytokine storm

Question 27

What bacteria is this and describe general characteristics of this bacteria.

Answer 27

Staphylococcus aureus G+ cocci in clusters, catalase +, coagulase +, beta-hemolytic Grows on Mannitol Salt Agar and Blood Agar: Yellow colonies Main Virulence Factor: Protein A Toxins: TSST, exfoliative toxin

Question 28

# S. Aureus What type of pneumonia occurs most commonly in what patient?

Answer 28

Patchy infiltrative pneumonia Typically occurs as a superinfection post-viral LRI.

Question 29

# S. Aureus Treatment

Answer 29

If Methicillin Sensitive - Nafcillin MRSA - Vancomycin

Question 30

# S. Aureus Endocarditis affects which valve and what patient population does it most commonly occur in?

Answer 30

Tricuspid valve - right sided Typically found in IV Drug Users

Question 31

# S. Aureus Symptoms and history of food poisoning related to this bacteria?

Answer 31

Typically causes vomiting without diarrhea General history includes meat or cream based foods

Question 32

# S. Aureus What is protein A?

Answer 32

Virulence factor that binds to Fc region of immunoglobulins preventing complement from binding and opsonizing/phagocytosing S. Aureus

Question 33

# S. Aureus What is exfoliative toxin and what disease is it known for?

Answer 33

A protease toxin found in S. aureus. Primary cause of Staph Scalded Skin Syndrome.

Question 34

# S. Aureus Toxic Shock Syndrome

Answer 34

Caused by leaving a foreign object in the body too long, such as a tampon or gauze after a rhinoplasty. Mediated by TSST toxin

Question 35

Name the pathogen and general characteristics including gram stain, shape, (un)encapsulated, hemolysis, and virulence factors

Answer 35

Streptococcus Pyogenes G+ cocci in chains, encaspulated with hyaluronic acid Beta-hemolytic Virulence Factors: Streptolysin O, Streptokinase, DNAses, M protein, Streptococcal Pyrogenic Exotoxin