Gram positive bacteria

Question 1

Staphylococcus aureus

Answer 1

Gram positive cocci in clusters
catalase positive
coagulase positive
staphylokinase-superantigen; release of cytokines
Exfo A&B- cause of SSSS
TSST-1
Folli, furun, carbun
Toxic Shock syndrome

Question 2

Coagulase-negative staphy

Answer 2

any species other than S. aureus
commensal
catheter-related illness
S. Lugd- endocarditis
S. Sapro- UTI

Question 3

Streptococcus

Answer 3

Gram-positive cocci in chains (except S. Pneumoniae)
Catalase negative
Hemolysis: beta-complete; alpha-incomplete; gamma-no
Lancefield grouping: A-W

Question 4

S. Pyogenes

Answer 4

Group A Strep
Strep Pyo Toxin(Spe A,B,C,F)
Streptoly S- hemolysin
Streptoly O- Oxygen labile
Streptokin A & B- plasminogen; blood clots
Pharyngitis- strep throat
scarlet fever- feet; strawberry tongue
Erysipelas- superficial
Necrotizing fasciitis- flesh eating bacteria
Rheumatic fever- heart valves
Acute Glomerulonephritis- kidney

Question 5

S. Agalactiae

Answer 5

Group B Strep
Mom: chemoprophy
Newborn: meningitis & pneumonia

Question 6

S. pneumoniae

Answer 6

gram positive cocci in pairs, “lancets”
gamma-hemolysis
Pneumolysin- cholesterol, induce cytokines
Autolysin- cell division
Pneumonia-chill & high fever, cough, blood-tinged

Question 7

Viridan group strep

Answer 7

30-40% endocarditis

immune-compromised patients

Question 8

Strep. bovis

Answer 8

Group D Strep
colon carcinoma (colon cancer)

Question 9

Enterococcus

Answer 9

antimicrobial resistance
gamma-hemolytic
E. feal, E. fealcium: acquired Van A, Van B
E. cassae, E. galli: intrinsic Van C

Question 10

Bacillus

Answer 10

gram positive rods

large, chaining, endospores

Question 11

B. anthracis

Answer 11

Select agent (Bioterror)
pXO1 gene- positive antigen(PA), edema factor(EF), lethal factor(LF)
pXO2 gene- polypeptide capsule
PA+EF=edema toxin, causes edema, cellular necrosis
PA+LF=lethal toxin, causes cellular necrosis
Anthrax- cutan(eschars), gastrointestinal, inhalation(deadliest form)

Question 12

B. cereus

Answer 12

food poisoning- intoxication from preformed toxin
Heat-labile: emetic form (intoxication), v.n.c.
Heat-labile: diarrhea form (intestine), v.n.c. w/ fever
ocular infection- traumatic penetrating injury

Question 13

corynebacterium diphtheriae

Answer 13

Diphtheria toxin- A-B exotoxin encoded by tox gene (genetic transfer from lysogenic bacterophage)
inhibits host cell protein synthesis, leading to cell death
Diphtheria- respiratory & cutaneous disease
Pharngitis leading to pseudomembrane formation (dead host cell, bacteria, immune cells)
“bull neck”
Lymphocytosis present

Question 14

Listeria monocytogenes

Answer 14

Tumbling motility, growth in cold temp.
cell-to-cell invasion from being “pushed” from one cell into adjacent cell by host cell actin
illness from contaminated/unpasteurized food

Question 15

Erysipelothrix rhusiopathiae

Answer 15

Pleomorphic rods
Erysipeloid- fish handler’s disease
localized skin infection

Question 16

Nocardia

Answer 16

Branching GPR, medium mycolic acids
respiratory disease - bronchopulmonary, most frequently in immunocompromised persons
Cutaneous disease - actinomycetoma: painless, chronic infection (N. brasiliensis)

Question 17

Mycobacterium

Answer 17

long mycolic acid
waxy
fast growers: 3-5 days for growth; 2-4 weeks

Question 18

Mycobacterium tuberculosis

Answer 18

Tuberculosis
consumption
destruction of lung tissue
formation of granulomas ("tubercles") in lung
cough with blood sputum
insidious onset

Question 19

Mycobacterium leprae

Answer 19

cannot be cultured
grows in the footpads
Tuberculous leprosy - celluar immune reaction, lyphocytes and granulomas in tissue with bacteria
Lepromatous leprosy - antibody response, cellular response, classic leprosy; disfiguration , large lesion present