Chapter 10-11 Intro Staphylococcus

Question 1

what do the different gram stains reflect

Answer 1

a fundamental differentiation based on permeability, presence or absense of outer membrane and cell wall thickness

Question 2

what are the 4 typical cell types

Answer 2

• gram positive rods
• gram positive cocci
• gram negative rods
• gram negative cocci

Question 3

do gram positive rods have more in common with gram positive cocci or gram negative rods

Answer 3

gram positive cocci

Question 4

what group does staphylococci fall under

Answer 4

gram positive cocci

Question 5

what group does streptococci fall under

Answer 5

gram positive cocci

Question 6

where are staphylococci found and what type of infections is it associated with

Answer 6

-skin infections and wounds
- carbuncles
-abscesses
-leading to life threatening deep tissue infections
-osteomyelitis
-endocarditis
- severe intoxications
-food poisoning

Question 7

what are the groups of streptococci and what do they do

Answer 7

-alpha: S. pneumoniae
-beta: groups A-T, group A most prevalent in human disease

Question 8

describe the type of microbe streptococci id

Answer 8

oxygen tolerant anaerobes

Question 9

what are the major gram negative cocci

Answer 9

-neisseria meningitidis
- neisseria gonorrhea

Question 10

what are the major gram positive rods

Answer 10

• non spore forming aerobic rods - corynebacterium diptheriae and related diptheroids
• spore forming rods

Question 11

what are the aerobic spore forming rods of gram positive rods

Answer 11

bacillus anthracis

Question 12

what are the anaerobic spore forming rods of gram positive rods

Answer 12

• clostridium species
• c. botulinum, c. tetani, c.perfringens, c. difficile

Question 13

what are the major gram negative rods

Answer 13

• enteric bacteria
• enterobacteriaceae
  -escherichia coli, salmonella spp, shingella spp, yersinia, pseudotuberculosis
• vibrio cholerae, camyplobacter jejuni, helicobacter pylori

Question 14

what are the major non-enteric gram negative rods

Answer 14

• pseudomonas aeurginosa
  -haemophilus influenzae
• bordetella pertussis
• brucella abortus
• legionella penumophila

Question 15

what type of microbe is enterobacteriaceae

Answer 15

facultative anaerobes

Question 16

what are the strictly anaerobic gram negative rods

Answer 16

bacteroids gragilis

Question 17

where is bacteriodes fragilis found

Answer 17

-most common organism in the intestine
- gingival pockets

Question 18

example of acid fast bacteria

Answer 18

mycobacterium tuberculosis
- M. leprae

Question 19

what are examples of spriochetes

Answer 19

-treponema pallidum (syphilis)
- leptospira spp (hemorrhagic fever)
- borrelia recurrentis ( relapsing fever)
- borrelia burgdorferi (lyme disease)

Question 20

what are the strictly intracellular bacteria

Answer 20

• chlamydia trachomatis
• chlamydia pneumoniae
• rickettsiae (rocky mountain spotted fever)
• ehrlichia (arthropod borne)
• coxiella burnetti (Q fever)

Question 21

what is the most common STD

Answer 21

chlamydia trachomatis

Question 22

what are the characteristics of staphylococcus

Answer 22

-gram positive cocci
- catalase positive

Question 23

what type of microbe is staphylococcus aureus and what does that mean about O2

Answer 23

facultative anaerobe
- O2 can be used

Question 24

what does a catalase do

Answer 24

reduced the potential of phagocytes to kill

Question 25

what does a coagulase do

Answer 25

binds prothrombin: fibrinogen is cleaved -> anti-phagocytic fibrin coating

Question 26

the tissue invasive potential of staphylococcal infections is directly proportional to ______

Answer 26

coagulase proudction

Question 27

what does clumping factor do

Answer 27

fibrinogen binding protein: cell surface proteins that bind to foreign materials and ECM

Question 28

what does protein A do

Answer 28

anti-phagocytic - competes with neutrophils for Fc protion of opsonizing IgGs

Question 29

what does leukocidin do

Answer 29

secretion: inhibits phagocytosis by granulocytes by forming pres in phagosomal membranes and kills phagocytes

Question 30

what does staphylokinase do

Answer 30

converts plasminogen to plasmin, increasing invasion by digesting fibrin clots and cleaves C3b and IgG to inhibit phagocytosis

Question 31

what does beta lactamase do

Answer 31

enzymatic digestion of penicillins

Question 32

what do alpha hemolysins do

Answer 32

pores are hemolytic, leukocytic, destroy skin, cause smooth muscle paralysis

Question 33

what do beta hemolysins do

Answer 33

- beta hemolysins are cytolytic sphingomyelinases that destroy nerves

Question 34

what do gamma hemolysins do

Answer 34

lyse related leukocicin on neutrophil lysosomal membranes

Question 35

does staph aureua do hemolysis

Answer 35

yes beta

Question 36

does staph epidermidis do hemolysis

Answer 36

no

Question 37

what microbe causes impetigo

Answer 37

S. aureus

Question 38

what is empyema

Answer 38

collection of pus in a naturally existing anatomical cavity

Question 39

what are pyogenic infections and wjat is it caused by

Answer 39

pus forming - massive amounts of neutrophils and other leukocytes are lysed by bacterial factors and release their lysosomal contents in attempting phagocytic killing of the staphylococci

Question 40

how does bacteremia fever progress

Answer 40

folliculitis -> furuncles -> carbuncles -> systemic bacteremia fever

Question 41

what do superantigens do

Answer 41

override the specificity of the T cell response

Question 42

what is the cause of gastrointestinal upset typical of food poisoning

Answer 42

enterotoxins

Question 43

what happens in toxic shock syndrome

Answer 43

- TSST: mass activation of T cells leads to large production of inflammatory cytokines

Question 44

are enterotoxins heat stable

Answer 44

yes cooking doesnt help

Question 45

describe exfoliative toxin

Answer 45

heat stable, chromosomal

Question 46

describe exfoliative toxin B

Answer 46

heat labile, plasmis

Question 47

what is Toxic shock syndrome caused by

Answer 47

increased oxygenation of vagina by tampons and foreign surface adhesion caused massive growth

Question 48

what is staphylococcal scalded skin syndrome caused by and what is it

Answer 48

-exfoliative toxins A, B - causes loss of layers of the skin

Question 49

when is nosocomial staphylococci of concern

Answer 49

surgery, implant and instrument risk

Question 50

what type of microbe is a nosocomial infection caused by

Answer 50

coagulase negative S epidermidis

Question 51

what microbe causes endocarditis

Answer 51

- acute: 60% S aureus - if artificial heart vavles 80% S. epidermidis

Question 52

what microbe is involved in dental extraction risk

Answer 52

S epidermidis

Question 53

what is the most frequent cause of bacterial arthritis

Answer 53

S. aureus

Question 54

what is the epidemiology of staphylococcus aureus

Answer 54

- skin + mucosa + aerosols - surface survival - nosocomal - high temperature and salt resistant

Question 55

how many beta lactamase (plasmid) are penicillin resistant

Answer 55

>90%

Question 56

what causes methicillin resistance

Answer 56

penicillin binding protein 2a

Question 57

what percentage of hospital strains of staph aureus are MRSA

Answer 57

50%

Question 58

what percentage of community strains are MRSA

Answer 58

20%

Question 59

what are the coagulase negative staphylococci

Answer 59

S. epidermidis or S. saprophyticus

Question 60

describe the coagulase negative staphylococci

Answer 60

- thick cell wall, slime capsule: S. saprophyticus: urease secretion -> acute cystitis - opportunistic hospital pathogens