Bailey Flashcards
(68 cards)
1
Q
6 steps in infectious disease process
A
- encounter
- entry
- spread
- multiplication
- damage
- outcome
2
Q
encounter
A
natural resivoir of infectious microbe
encounter does not mean infection
3
Q
entry
A
pathogens must enter body in order to establish infection
4
Q
colonization/invasion
A
colonize a surface before causing disease, adhere to host tissue
colonize-patho must be adated for growth in niche
invade-must have specific virulence factors
5
Q
multiplication/spread
A
- lateral prop to contiguous tissues
2. dissemination to distant sites, then multiple
6
Q
damage
A
- host response (phagocytes, cytotoxic T cell)
- infectious organism
- types of toxins
7
Q
outcome
A
resulting illness
8
Q
what are the two processes for entry into a host?
A
- ingress of microorganisms into body cavities contiguous with outside (inhalationg/ingestion)
- penetration of microorganisms into deeper tissues after crossing epi barrier (bites, cute, transplants, transfusions)
9
Q
what body areas are considered in direct contact with exterior?
A
nose, mouth, resp tract, alimentary cnal, anus, female genital tract, urinary tract
10
Q
2 steps of penetration of bacteria into epi cells
A
- attachment to specific receptors
2. internalization
11
Q
2 meanings of spread of infection
A
- lateral propagation/movement to contiguous tissues
2. dissemination to distant sites
12
Q
what must microbes over come in order to multiply and spread?
A
host defenses
13
Q
inoculum size is important in establishing _____
A
an infection (varies with different organisms)
14
Q
4 possible outcomes of a host-parasite interaction
A
- host wins out and clears infection
- parasite overcomes the host
- host and parasite adapt to each other
- neither host or parasite win (chronic inf can continue indefinitely)
15
Q
how can damage to the host be caused?
A
- infectious agent
- host response (immune system)
- both
16
Q
the great majority of microorganisms are _____
A
commensal
17
Q
commensal
A
exist without causing harm
18
Q
gram positive bacteria have _____
A
thick cell wall made of murein (peptidoglycan)
19
Q
composition of murein
A
long chains of N acetylmuramic acid and N acetylglucosamine linked by short polypeptides
20
Q
gram negative bacteria have _____
A
thin layer of murein between two membrane lipid bilayers
21
Q
what is the outer layer of gram negative bacteria made of?
A
lipopolysaccharide (LPS)
-is different for different bacteria
22
Q
lipopolysaccharide (LPS)
A
- different for different bacteria
- toxic (endotoxin) even in its purified form
- Lipid A (fatty acids attached to phosphorylated disaccharide) that faces into mem and a polysaccharide core faces out
- outer (O antigen) region is variable and antigenic, provides differences between gram - bac
23
Q
bactericidal
A
kill bacteria
24
Q
bacteriostatic
A
inhibit growth
25
penicillins (and other beta lactams)
antibiotics that affect cell wall, bactericidal
26
how do antibiotics often work?
by targeting bacterial ribosomes
27
what are the 2 bacterial ribosome subunits
30S
| 50S
28
what is the 30 s subunit responsible for?
translation of mRNA
29
what is the 50 s subunit responsible for?
joining amino acids together and moving the complex alone the mRNA molecule
30
which subunit do antibiotics target?
both
31
what inhibits folic acid metabolism?
sulfonamides and trimethoprim
32
what inhibits protein synthesis?
aminoglycosides, tetracyclines, and erythromycin
33
what inhibits DNA synth
metronidazole
34
what do pili (fimbriae) do
they are specialized structures on the surface of bacteria that are involved in adhesion to cells or other surfaces
35
what do sex pili do?
special pili that link a donor cell to a recipient cell during transfer of DNA
36
flagella
surface structures used for locomotion
| they cause movement when they rotate CCW and tumbling when CW
37
what is flagellar movement used by?
bacteria for chemotaxis- movement toward substances that attract, away from substances that repel
38
strict aerobes
must have O2 to grow
39
obligate anaerobes
cannot tolerate O2
40
facultative anaerobes
can grow with or without O2
41
obligate intracellular parasites
can only grow inside host cells
42
therapeutic index
ratio between effective and toxic dose of an antibiotic
43
what do antibiotics tend to target
structures that are unique in bacteria vs host cells
- cell wall
- enzymes for replication, transcription, translation
- essential metabolites
- ribosome structure
44
how penicillin disrupts cell wall
inhibits final step of peptidoglycan synthesis, prevents crosslinking of peptidoglycan molecules
45
how do bacteria become resistant to antibiotics?
1. synthesizing enzymes that inactivate the drug
2. inhibiting uptake of the drug
3. increasing secretion of the drug (pumping it out of the cell)
4. modifying the target of the drug
46
where are drug resistant genes often found?
on plasmids that can be transferred readily from one bacteria to another
47
in order to survive as an infective agent, bacteria must
1. avoid being washed away
2. find a nutritionally compatible niche
3. survive host cell defenses
4. transfer to a new host
48
what causes damage to a host cell as a result of infection?
1. cell death
2. pharmacologic alterations of metabolism
3. mechanical causes
4. host responses
5. bacterial toxins
49
pathogen associated molecular patterns
structures on microbial surface consisting of repeated molecules
50
pattern recognition receptors
recognize pathogen associated molecular patterns
51
how are abcteria often classified?
via surface antigens (serotype)
52
how do pathogens adhere to host tissue?
1. nonspecific adherence
| 2. specific adherence
53
nonspecific adherence
1. reversible
| 2. docking
54
specific adherence
1. irreversible
| 2. anchoring
55
what does specific adherence involve?
adhesins
56
adhesins
substances on the surface of microbes, often found on pili, interactions are specific
glucosyl binds to salivary protein in pellicle and binds strep mutans
57
how do bacteria take u nutrients
1. carrier-mediated diffusion (facilitated)
2. phosphorylation linked transport (group translocation)
3. active transport (energy dependant)
58
types of toxins
endotoxin: component of cell wall, generally reserved for lipopolysaccharide
exotoxins: soluble substances secreted into host tissues
59
what makes a microbe a pathogen
1. ability to adhere to host
2. ability to colonize the host
3. ability to replicate within given niche
4. ability to cause damage
60
categories of bacteria based on environment
1. oligotrophs: can grow w/ limited nutrients
2. microaerophiles: require some O2, but low levels
3. mesophiles: grow well in mild temps (15-45 C)
61
why are LPS important?
- considered pathogen associated molecular patterns (PAMPs)
| - PRRs can recognize PAMPs
62
glycocalyx
substance surrounding cell, capsule when well organized, slime layer when not
63
why would capsules be beneficial to pathogens?
for some bact, encapsulation is a necessary virulence factor
64
5 ways antibiotics inhibit bacteria
1. inhibit cell wall synthesis
| 2.
65
5 ways antibiotics inhibit bacteria
1. inhibit cell wall synthesis
2. disrupt cell membrane function
3. inhibit protein synthesis
4. inhibit nucleic acid synthesis
5. act as antimetabolites
66
antibiotics commonly used in dentistry and their purpose
1. penicillin: odontogenic infection
2. clindamycin: odontogenic infection (bone), abscesses
3. cephalosporins: odontogenic infection
4. metronidazole: abscesses and periodontitis
5. tetracyclines: periodontitis
67
mechanisms of drug resistance
1. synthesis of enzymes that inactivate the drug
2. prevention of access to target site (inhibit uptake or increase secretion of drug)
3. modification of target site (via enzyme affinity or metabolid pathway)
68
how does antibiotic resistance spread?
1. chromosome associated resistance
2. plasmid mediated resistance
3. rapid spread resistance
