Bailey Lecture 1 Gram - Streptococci

Question 1

What are the two main prolific colonizers of mucosal surfaces?

Answer 1

1) enterobacteriaceae
2) vibrionoaceae

Question 2

What do you call a surface that interacts with air that has associated glands for secreting mucus?

Answer 2

mucosal surface

Question 3

What are the 4 areas of the body that have mucosal surfaces?

Answer 3

1) oral cavity
2) respiratory tract
3) reproductive/urinary tract
4) gastrointestinal tract

Question 4

What are 3 defense mechanisms for mucosal surfaces?

Answer 4

1) innate innumity
2) adaptive immunity
3) nonspecific barrier defenses

Question 5

for some bacteria, as few as _____ - _____ organisms is enough to cause disease (Shingella dysenteriae for example). For others, millions are required

Answer 5

50-100

Question 6

What are 3 natural barrier defenses against gram - bacteria?

Answer 6

1) secretory substances
2) anatomical and physiological barriers
3) indigenous microbiota

Question 7

How many layers of epithelial cells separate the interior of the body from the microbes on mucosal surfaces?

Answer 7

1

Question 8

In the GI tract, what is the pH range of the surface?

Answer 8

1-9 (acidic)

Question 9

What types of junctions in the GI tract prevent “seeping” of surface substances into the internal body cavity?

Answer 9

tight junctions

Question 10

Question 11

A lysozyme (AKA muramidase) is a secretory _____ compound that cleaves _____ linkages between _____ & _____

Answer 11

a lysozyme (AKA muramidase) is a secretory antimicrobial compound that cleaves BETA 1,4-GLYCOSIDIC LINKAGES between ACETYLNURAMIC ACID and N-ACETYLGLUCOSAMINE

Question 12

Lactoferrin is a secretory antibacterial compound that does what?

Answer 12

has BACTERIOSTATIC effects because it causes IRON SEQUESTRATION

Question 13

Cathelicidin is a secretory antimicrobial compound that works on both gram - and gram + bacteria by doing what?

Answer 13

cathelicidin disrupts bacterial membranes of gram - and gram + (as well as fungi)

Question 14

Defensins, a type of secretory antimicrobial compound, works by doing what?

Answer 14

creating pores in microbes (all microbes can be affected)

alpha defensins produced by NEUTROPHILS and PANETH CELLS (in intestine)

beta defensins produced by epithelial cells

Question 15

What are three mechanisms that bacteria can avoid being destroyed by secreted antibacterial substances?

Answer 15

1) acid resistance. microbes with low infectious dose tend to be acid resistant (shingles and e. coli)
2) fimbriae/pili which adhere to tissue to resist being shed
3) bacterial structures such as cationic amino acids into cell membranes to reduce effects of cationic antimicrobial peptides as well as siderophores which sequester iron into low iron environments (e.g. enterobactin produced by e. coli)

Question 16

macrophages are an important part of mucosal immunity. they recognize microbes via _____ which leads to the activation of the macrophages which will kill many microbes

Answer 16

pattern recognition receptors

Question 17

Within the phagolysosomes of macrophages, microbes are killed with what compounds?

Answer 17

ROS and NO as well as lysosomal enzymes

Question 18

Activation of pattern recognition receptors on macrophages also initiates what?

Answer 18

the inflammatory response

Question 19

What are the three inflammatory cytokines that are called to action by macrophages?

Answer 19

TNF-alpha, IL-1, IL-12

Question 20

What is the drawback to the inflammatory reaction that macrophages stimulate at mucosal surfaces?

Answer 20

inflammatory cytokines such as TNF-alpha can disrupt the TIGHT JUNCTIONS between epithelial cells

Question 21

Another bacterial defense, _______, helps it resist phagocytosis

Answer 21

capsule

Question 22

Some bacteria avoid the effects of phagocytosis by doing what?

Answer 22

develop mechanisms that are capable of neutralizing the phagocytic compartment of macrophages

Question 23

Where are the densest clusters of lymph nodes found?

Answer 23

near mucosal tissues

Question 24

The ______ immune response is generated in the lymph nodes

Answer 24

adaptive immune response

Question 25

Invasive bacterial pathogens include what two genuses?

Answer 25

salmonella and shigella. Both occupy the large intestine and can have several effects including small stool volume, bloody stool, leukocytes in stool, and tissue ulcerations

Question 26

Toxin-producing bacterial pathogens include what two genuses?

Answer 26

Vibrio (primarily V. cholerae) and entertoxigenic E. coli (ETEC). Both occupy the small intestine and evidence of infection by one of these two include copious amounts of watery stool, no blood in stool, no leukocytes in stool, and no tissue damage

Question 27

Hybrid “misfit” pathogenic genuses include what?

Answer 27

Enterohemorrhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC). These occupy the lower small intestine and upper large intestine and cause attaching and efffacing lesions with blood in stool (and also possibly blood in urine with EHEC)

Question 28

dysenteriae, flexneri, boydii, and sonnei are all species of what type of invasive bacterial pathogen?

Answer 28

Shingella. These four species are distinguished by the O antigen

Question 29

Do shigella have a large or small inoculum size?

Answer 29

very small

Question 30

What facilitates the survival of shigella through the stomach?

Answer 30

acid resistance which is controlled by a global regulatory system of genes under the control of RpoS made in the stationary phase. This occurs when Shigella are grown anaerobically. In the end, they will usually multiply in and colonize the colon

Question 31

_____ & _____ allow shigella to enter the otherwise impermeable intestinal mucosal surface

Answer 31

M cells and invasion plasmid antigens. One the shigella enters the lamina propria and are ingested by macrophages, the inflammatory response causes signs of illness (activation of CD4+ cells)

Question 32

After shigella lyse the macrophage that has ingested it, intracellular spread is facilitated by what?

Answer 32

IcsA, an ATPase that causes actin polymerization that assists with cell-to-cell spread

Question 33

What causes the formation of an ulcer?

Answer 33

an ulcer forms when invaded cells die and slough of

Question 34

_____ can be seen by microscopy in stool samples during a shigella infection

Answer 34

neutrophils

Question 35

Shigella sonnei is unusual for a shigella because it not only causes diarrhea and neutrophils in the stool but also causes what?

Answer 35

watery stool

Question 36

Shigalla dysenteriae type 1 is special because it in addition to the usual properties of a shigalla, it also produces what?

Answer 36

Shiga toxin which kills intestinal epithelial and endothelial cells, disrupting Na absorption

Question 37

Different species of Salmonella have various effects on the body. S. typhimurium and S. enteritidis tend to cause what?

Answer 37

gastroenteritis

Question 38

Different species of Salmonella have various effects on the body. S. choleraesuis and S. typhimurium cause what?

Answer 38

focal infections of vascular epithelium

Question 39

Different species of Salmonella have various effects on the body. S. typhimurium causes what?

Answer 39

infections of organ systems

Question 40

Different species of Salmonella have various effects on the body. S. typhi and S. paratyphi cause what?

Answer 40

typhoid fever

Question 41

Does Salmonella require a small or large inoculum?

Answer 41

large (10-100 million)

Question 42

How is salmonella primarily transmitted?

Answer 42

fecal-oral

Question 43

What is more acid-sensitive? Salmonella or Shigellae?

Answer 43

salmonella

Question 44

For Salmonella, low pH induces the expression of at least 40 proteins found on _____ on large virulence plasmids

Answer 44

pathogenicity islands

Question 45

Describe the invasion process for salmonella

Answer 45

1) organisms approach cell surface, induce cell signaling pathways which cause an increase in cellular Ca2+
2) these events induce surface “ruffles” which causes uptake of organisms
3) organisms remain within cell vesicles for many hours (unlike shigella)
4) organisms are released to lamina propria and causes Na & Cl loss from the host cells
5) macrophages engolf most but some escape to cause a transient bacteremia (the typhoid serovars will survive and grow within the macrophages)

Question 46

Salmonella typhi enters what system and replicates within what?

Answer 46

enters the lymphatic system and replicates within macrophages

Question 47

Can salmonella be reserved in animals?

Answer 47

no

Question 48

Asympomatic typhoid carriers are known as what?

Answer 48

typhoid mary

Question 49

Carriers of typhoid mary have colonized what?

Answer 49

gall bladders

Question 50

Typhoid septicemia results in what?

Answer 50

fever and infection of kidney and other organs

Question 51

What is the effect of typhoid fever on the small intestine?

Answer 51

inflammation, ulceration of peyer’s patches leading to diarrhea, hemorrhage, and perforation

Question 52

Invasive pathogens are identified based on what?

Answer 52

symptoms and stool cultures

Question 53

Antibiotic resistance was first identified in what?

Answer 53

shigella (treated with fluoroquinolones and B-lactams)

Question 54

Do you usually treat salmonella gastroenteritis with antibiotics?

Answer 54

you can, but normally you don’t

Question 55

What is the treatment required for typhoid fever/typhoid mary?

Answer 55

fluoroquinolones or surgical removal of gallbladder (vaccine to the capsule of S. typhi)