Flashcards in 63/65-C. Diff and Meningitis Exemplar Deck (58)
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1
microbial exposure is constant
but clinical infection is rare
2
5 obligatory capabilities of microbes
attachment
spread
replication
evasion
transmission
3
risk of infection
dose*virulence
_____________
host resistence
4
dose
number of organisms
5
virulence
sum of organisms properties that help it cause infection
6
resistance
resistance of the host to infection, depending on anatomy and immune system
7
infection earlier in sequence
reliance on preformed effector molecules using non specific recognition molecules
8
infection later in sequence
synthesis of effector molecules, depends on specific recognition molecules
9
time for barrier
0-4 hours
10
time for innate
4-96 hours
11
time for adaptive
96+ hours
12
stages of infection
adherence
penetration
local infection
lymphatic spread
adaptive immunity
13
clinical reasoning
mechanisms
clinical presentation
context
14
inflammation in colon
increase mucous, peristalsis, bleeding
15
types of barriers
mechanical, physical, chemical, microbiome
16
epithelial cells
tight junctions, don't leak
17
barriers to infection
non-specific
use preformed effector molecules so response is fast
use antimicrobial peptides (defensins)
18
chemical protection of gut
low pH
enzymes
antimicrobial peptides
19
antimicrobial peptides
defensins, cathelicidin, regIII
punch holes in bacterial membrane to kill
20
GI host defense
low pH, acidity
motility
mucous
bacterial colonization
GI mucosal immunity
21
GI mucosal immunity
sIgA and IgG
lymphoid follicles
Peyer's patches
M cells
22
microbiome
all microbes, their genome, and environmental interactions
important for GI function and overall health
23
development of microbiology of GI tract
Sterile at birth
becomes colonized with maternal flora
initial colonization: aerobic (lactobacilli), create reducing environment
subsequent colonization: anaerobic
24
gut becomes colonized with commensal bacteria
mucosal becomes anti inflammatory
if infected it shifts to pro inflammatory
25
gut bacteria
outnumbers human cells 10x
quantity varies along GI tract (more at end)
Humans rely on gut bacteria
26
functions of gut bacteria
metabolic functions-breakdown sugars, produce vitamins
educate immune system
27
mucosa associated microbes
commensal symbionts
bidirectional induction of gene expression (microbe influence human and vice versa)
metabolism
nutrition
immune (anti inflammatory)
28
tight junctions
IL-10: anti inflammatory
IL-17: inflammatory, leaky
29
ID50
# or organisms needed to cause disease in 50%
30
ID 50 in gut
lots needed for infection
fewer needed if passed through skin barrier
antibiotics clear microbiome and decrease ID50 by 30,000x
31
decrease ID 50
break barrier, antibiotics to clear microbiome, exposure to new bacteria
32
C. diff
lives as a spore
produce cytotoxins A and b
33
causes of C diff
old age
Hospitalization
medications - broad spectrum, proton pump inhibitors, chemotherapeutic drugs
34
4 forms of c diff
short term colonization
acute diarrhea
recurrent diarrhea
fulminant diarrhea
35
symptoms of c diff
fever
cramping
adb pain
bloody diarrhea
fecal PMN
36
Antibiotics and c diff
disrupt microbiome
37
PPI and c diff
lower gastric pH so microbes can grow
38
chemotherapeutic agents
disrupt GI epithelium
39
treatment for c diff
fecal transplant
vancomycin or metronidazole
40
increase risk of GI infection
foods or meds that neutralize or reduce gastric acid secretion
pernicious anemia
gastrectomy
41
Petechiae
non blanching, tiny red spots
extravasation of blood from capillaries
42
purpura
large, dark irregular shaped lesions
significant bleeding into soft tissue
43
ecchymoses
coalesced purpura
44
left shift
marrow is stressed and releasing immature cells
45
n. meningitidis
gram negative coccus
46
structure of meningococcal cell wall
lipopolysaccharide for exotoxin
pilus for attachment
capsule with negative charge
47
pili
specific attachment to non ciliated nasopharyngeal cells or damage to ciliated cells
48
Lipopolysaccharide
LPS and CD14 form complex
recognized by TLR and causes inflammation with NF-kB
Cytokine release for T cell mediated immunity, B cell humoral immunity, or sepsis
49
hallmark of inflammation and infection
leukocytes and left shift
50
serum protein during inflammation
normal albumin>globulin
infection albumin
51
local inflammation in infection
increased permeability
52
systemic protective actions in infection
brain-fever
liver-acute phase proteins
bone marrow-leukocyte production (increase PMN, left shift)
53
systemic pathologic effects in inflammation
heart-low output, low BP (renal failure), increased o2 demand (hypoxia), acidosis
blood vessel-increased permeability, vasodilation, leaky vessels, petechia and purpura
54
capsule on bacteria
fight with anticapsular antibody
55
greatest risk for bacterial meningitis
first 2 years of life
56
pure capsular vaccine
Ineffective before 2 years, shorter immunity, no memory t cells
57
conjugate vaccine
effective at all ages, longer immunity, recruits t cell memory
58
