Cocci

Question 1

cocci

Answer 1

• spherical
• 1 micron diameter
• non-spore forming
• human restricted
• gram staining
• twos, chains, clumps
• alpha,beta,gamma hemolytic
• strep, staph, neisseria

Question 2

streptococci

Answer 2

• gram positive
• catalase negative
• grows in chains
• classified by Lancefield or hemolytic abilities
• cell wall has pili

Question 3

Group A strep

Answer 3

• sore throats
• gram positive
• beta hemolytic
• sensitive to bacitratcin
• reacts to group A antiserum, rapid test to carb antigen but false negatives are common
• S. pyrogenes

Question 4

Lancefield classification

Answer 4

-based on carbohydrate antigens found in the cell wall

Question 5

group A virulence

Answer 5

• pili-pathogenicity island
• M protein
• streptokinase
• streptodornase
• hyaldronidase
• pyrogenic toxin
• erythrogenic toxin

Question 6

reservoir and transmission of group A

Answer 6

• spreads from oropharynx to tonsils/floor of mouth or to middle ear/mastoids/meninges
• reservoir is carriers
• transmitted by direct contact

Question 7

post strep conditions

Answer 7

• skin infection from M49-pain, blood and protein in urine-post strep nephritis
• sore throat from M18-fever, arthritis, endocarditis-rheumatic fever
• occur after infection
• lesions are sterile (but there are antibodies in blood)
• sydenhams chorea-neurological symptoms

Question 8

Group B strep

Answer 8

• gram pos, catalase neg, beta hemolytic, resistant to bacitracin, positive CAMP test, reacts to Group B antiserium
• S. agalactiae

Question 9

Group B virulence

Answer 9

capsule-prevents phagocytosis

Question 10

reservoir and transmission

Answer 10

• genital tract of 25% of women

- neonatal to baby- can lead to meningitis

Question 11

prevention of group B CDC recommendations

Answer 11

• offer penicillin prophylaxis to pregnant women is
• vaginal/rectal swab shows group B at 35 weeks or previous baby with group B
• fever
• membranes ruptured for over 18 hours

Question 12

S. pneumoniae

Answer 12

• pneumococci, dipplococci

- gram pos, catalase neg, alpha hemolytic, sensitive to bile

Question 13

virulence of pneumococci

Answer 13

• capsule-prevents phagocytosis
• antigen as well, stimulates opsonization
• 80 types
• basis of typing sera and vaccines
• basis of polyvalent antibody reaction-quellung

*reservoir-5-50% of throats

Question 14

pathogenesis of bacterial pneumonia

Answer 14

• natural resistance to lung infection from mechanical clearance by mucus/cilia
• inhibition of mechanical clearance leads to disease
• smoking
• virus
• allergy
• immobility
• mechanical-tumors/foreign bodies
• depressed cough reflex-alcohol/narcotics
• L sided heart failure

Question 15

management of bacterial pneumonia

Answer 15

• offer vaccine to susceptible groups
• identify and treat the underlying cause
• antibiotic sensitivity tests
• antibiotics

Question 16

S viridans

Answer 16

-gram pos, catalse neg, alpha hemolytic, bile resistant

Question 17

reservoir and transmission of S viridans

Answer 17

• mouth- 100%

- transmission from person to person

Question 18

virulence of S viridans

Answer 18

• sugar metabolizing enzymes
• some increase MW, dental plaque, bactermia and endocarditis
• others break down to acids-decalcification
• bacteremia managed by prophylactic antibiotics at dentist

Question 19

enterococcus fecalis

Answer 19

• gram pos, catalase neg, gamma hemolytic, resistant to bile, or reacts to group D antiserum
• normal flora of colon
• resistant to penicillin-use penicillin and aminoglycosides

Question 20

peptostreptococcus

Answer 20

• gram pos, catalase neg, gamma hemolytic, sensitive to bile
• found in abscesses with a mixture or organisms, not primary pathogens
• normal flora of mouth, resp tract, female genital tract, bowel

Question 21

staphylococci

Answer 21

• gram positive
• catalase positive
• accumulated mutations
• 6 resistance genes, at least 8 strains in existence now

Question 22

S. aureus

Answer 22

• gram pos, catalase pos, coagulase pos, beta hemolytic

- phage typing or DNA typing

Question 23

virulence of S aureus

Answer 23

• protein A-binds immunoglobulins
• capsule-prevents phagocytosis
• coagulase-makes things clot
• DNAse
• Enterotoxin
• Exfoliatin
• Leukocidin
• TSS Toxin
• MRSA

Question 24

reservoir and transmission of S aureus

Answer 24

• carriers on nose and skin

- direct contact with infected person or carrier, or indirectly by fomites

Question 25

prevention and treatment of S aureus

Answer 25

• wash hands, cover lesions, food hot, remove carriers from ICU, OR, nurseries, isolate, treat carriers
• drain abscesses to remove dead tissue and bacteria
• antibiotics-use penicillin pr oxacillin, methicillin
• MRSA use vancomycin

Question 26

S epidermidis

Answer 26

• gram pos, catalase pos, coagulase neg
• gamma hemolytic
• normal flora of skin and mucous membranes
• attaches to nylon and plastic- can infect IV caths, IV lines, shunts

Question 27

prevention and treatment of S epidermidis

Answer 27

• change catheters on schedule
• use gold or surgical stainless steel for decorative piercings
• peripheral catheters-72-96hrs
• emergency caths-within 48 hours
• iv tubing 72 hrs
• blood transfusion sets-within 24 hrs

Question 28

S saprophyticus

Answer 28

• gram pos, catalase pos, non hemolytic, coagulase neg

- can cause UTI

Question 29

gram neg cocci

Answer 29

• chocolate agar
• add to maltose
• fermentation is N. meningitidis, no fermentation is N. gonnorhoeae

Question 30

N. meningitidis

Answer 30

gram neg, fermentation pos

• capsule (vaccine), LPS
• resp tract of 5% of people, transmitted by droplets
• vaccine/penicillin

Question 31

N. gonorrghoeae

Answer 31

• gram neg, fermentation neg
• pili, LOS
• can be found in neutrophils
• sexual or neonatal transmission
• chronic infection may be asymptomatic
• ceftiaxone and doxycyline
• usually resistant to penicillin
• no vaccine