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DEN 7102 Micro & Immuno Concepts > Exam 2 Enteric Bacteria > Flashcards

Exam 2 Enteric Bacteria Flashcards

1
Q

Enteropathogenic bacteria - gram stain/shape?

A

Gram negative rods

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2
Q

Enteropathogenic bacteria - order and family

A

Order: Enterobacteriales
Family: Enterobacteriacae

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3
Q

The Enterobacteriaceae are able to cause infection through being both _____ and ______

A

Pathogens and opportunists

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4
Q

Which species are considered Enterobacteria pathogens? (5)

A
  1. Eschericia coli
  2. Shigella
  3. Salmonella
  4. Yersinia pestis
  5. Y. enterocolitica
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5
Q

Which species are considered Enterobacteria opportunists? (5)

A
  1. Klebsiella pneumoniae
  2. Proteus mirabilis
  3. Enterobacter
  4. Serratia
  5. Pseudomonas
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6
Q

Proteus mirabilis is often associated with what infection?

A

Urinary tract infection

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7
Q

What bacteria is this, and what are some of its characteristics?

A

E. coli; very mobile (peritrichous flagella) and covered with fimbrae so great for attachment

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8
Q

Pseudomonas is often associated with what infections?

A

Cystic fibrosis, burn patients

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9
Q

General characteristics of Enterobacteriaceae: what virulence factors do they have?

A
  • Endotoxin/LPS (O antigens)
  • Exotoxins (Enterotoxins)
  • Flagella (H antigens)

also have adhesion factors and capsules

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10
Q

Enterobacteriaceae metabolism

A

Facultative anaerobes; dif species have characteristic fermentation patterns so can be used to tell them apart

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11
Q

What are coliforms and which species are considered coliform bacteria?

A

Bacteria that shed a lot in our feces
- E. coli
- Klebsiella
- Citrobacter
- Enterobacter

Think “ICKY” (ECKE)

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12
Q

Coliform bacteria provide indices for:

A

Fecal contamination of drinking water (potability)

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13
Q

Regulatory standard for drinking water

A

<500 CFU/mL of water

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14
Q

Why is it important to consider CFU in drinking water standards?

A

CFU is live bacteria

live bacteria cause disease

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15
Q

Dental water quality: for routine dental treatment, meet _______

A

Regulatory standards for drinking water

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16
Q

E. coli is a ____ fermenter

A

Lactose

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17
Q

E. coli metabolism

A

Facultative anaerobe

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18
Q

E. coli makes tryptophanase to produce ____

A

Indole (organic compound)

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19
Q

E. coli can be cultured on what type of agar?

A

MacConkey agar (due to ability to ferment lactose, color will change to hot pink)

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20
Q

Indole test can be used to detect presence of:

A

E. coli

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21
Q

E. coli virulence factors

A
  • Adhesion factors
  • Enterotoxins (Heat labile toxin and Heat stable toxin)
  • Shigatoxin (verotoxin)
  • Hemolysins
  • Capsule

E. coli will CHASE me away

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22
Q

What enterotoxins does E. coli have?

A
  1. Heat labile toxin (LT-I and II) –> similar to cholera
  2. Heat stable toxin (ST), causes increase of intracellular cGMP
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23
Q

Which E. coli enterotoxin causes cGMP to increase?

A

Heat stable toxin (ST)

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24
Q

Most common cause of uncomplicated UTI in women

A

E. coli

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25
Q

UTI’s can have an ______ route of infection, leading to:

A

Ascending (urethra –> kidney) ; cystitis and pyelonephritis

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26
Q

What is cystitis?

A

Bladder inflammation

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27
Q

Cystitis strains have specific ____ adhesion factors

A

O antigens adhesion factors

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28
Q

What is pyelonephritis?

A

Kidney inflammation

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29
Q

Pyelonephritis strains have unique ____ antigens

A

P fimbrial antigens

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30
Q

E. coli UTI symptoms

A

Flank pain, turbid (cloudy) urine

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31
Q

Methods of E. coli UTI prevention

A
  • wash before and urinate after sex
  • wipe genitals from front to back
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32
Q

WBC casts are often a symptom of:

A

Pyelonephritis; produced by damaged kidneys and found in urine

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33
Q

Pyruria

A

Pus in urine

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34
Q

Diagnosis of UTI

A

Often diagnosed by symptoms; also 100,000 CFU/mL of urine, PMN, WBC casts

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35
Q

What strains of E. coli produce intestinal infection?

A
  • EHEC
  • STEC
  • ETEC
    (6 pathotypes in total; there are others but they’re not in red or blue)
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36
Q

What is EHEC and what does it cause?

A

Enterohemorrhagic E. coli; causes bleeding in the gut

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37
Q

What is STEC?

A

Shiga Toxin producing E. coli

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38
Q

Shigatoxin (Stx) is encoded by:

A

Lysogenic phage

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39
Q

Shigatoxin can be acquired by eating ____

A

undercooked beef

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40
Q

What infections can intestinal shigatoxin lead to?

A

Hemorrhagic colitis, hemolytic uremic syndrome (HUS)

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41
Q

ETEC is known as:

A

Traveler’s and infants watery diarrhea

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42
Q

True or false: ETEC watery diarrhea is non-invasive

A

True - doesn’t spread from gut to rest of body

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43
Q

ETEC includes what toxins?

A

Heat labile toxin, Heat stable toxin

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44
Q

What is the most common strain of STEC in the US?

A

O157:H7
O = LPS antigen
H = flagellar antigen

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45
Q

Hemorrhagic colitis incubation time

A

3-4 days

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46
Q

Where/how does STEC colonize the gut to cause hemorrhagic colitis?

A

Invades colon epithelial cells causing acute inflammation

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47
Q

Hemorrhagic colitis symptoms

A

Severe abdominal pain, bloody diarrhea, mucus, PMN

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48
Q

True or false: Fever is reported as a common symptom of hemorrhagic colitis

A

False - little or no fever (usually lasts a week)

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49
Q

STEC transmission

A

Fecal-oral
- through ground beef
- contaminated water, unpasteurized milk and juice
- sprouts, lettuce, spinach, salami (animal waste can be found in fertilizer)

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50
Q

Hemorrhagic colitis therapy

A

Mainly rehydration. Don’t need antibiotics unless it spreads to rest of body (extra-intestinal)

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51
Q

Hemolytic uremic syndrome is caused by:

A

EHEC/Shiga Toxin

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52
Q

How does EHEC cause HUS?

A
  • toxin damages capillary lining
  • platelets clump to initiate healing
  • platelets form mesh in capillaries –> damages RBCs and prevents adequate blood flow
  • leads to organ dysfunction or failure
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53
Q

Most common cause of acute renal failure in children

A

Hemolytic Uremic Syndrome

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54
Q

HUS leads to what 3 outcomes?

A
  1. Microangiopathic hemolytic anemia/schistocytes (destroyed RBC)
  2. Thrombocytopenia (low blood platelets)
  3. Renal insufficiency (acute renal failure)
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55
Q

What toxins are associated with HUS?

A

Shiga toxin and LPS

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56
Q

True or false: treatment of HUS involves the use of antibiotics

A

False - could make the infection worse by releasing more LPS

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57
Q

What bacteria is this/characteristics?

A

Shigella; no flagella so is not mobile, but lots of fimbrae for attachment

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58
Q

True or false: Shigella can ferment lactose

A

False - No color change on MacConkey agar

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59
Q

____ is thought to be biogroups within E. coli

A

Shigella

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60
Q

Shigella sp. to know

A
  1. Shigella dysenteriae
  2. Shigella sonnei
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61
Q

____ causes most serious of bacillary dysentary

A

Shigella dysenteriae

epidemic in developing countries

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62
Q

Shigella dysenteriae is epidemic in:

A

Developing countries
(not found in US because we treat our drinking water)

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63
Q

Shigella sonnei (and flexneri) dominate in what country?

A

U.S.

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64
Q

What is dysentery?

A

Diarrhea with visible blood

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65
Q

Causes of dysentery

A

Bacterial - Shigella and STEC O157:H7

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66
Q

Most common cause of dysentery

A

Shigella sp.

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67
Q

Virulent strains of Shigella contain:

A

Large virulence/invasion plasmid

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68
Q

Shiga toxin is produced by which Shigella strain?

A

Shigella dysenteriae

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69
Q

Shiga toxin is derived from:

A

Phage

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70
Q

Structure of Shigatoxin

A

AB structure

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71
Q

What is the function of the A subunit in Shigella dysenteriae?

A

Inactivates ribosomes to stop protein synthesis, causes cell death and enterotoxic dysentery

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72
Q

What is the function of the B subunit in Shigella dysenteriae?

A

Binds to vascular endothelial cells (gut, kidney, lungs)

73
Q

Shigella enters small intestine through:

A

M cells

74
Q

Shigellosis is transmitted via:

A

Fecal-oral
- contaminated food and water

75
Q

True or false: Shigella has a very high infectious dose

A

False - very low (doesn’t take much to cause infection)

76
Q

What happens in the early/second stages of Shigellosis?

A

Early:
- colonization of small intestine, profuse watery diarrhea
Second:
- invasion of colon, fever, cramps, blood and pus in stool

earlystage MAY progress to second stage

77
Q

Shigellosis is usually self-limiting unless caused by:

A

Shigella dysenteriae

78
Q

Shigellosis may progress to _____

A

Hemolytic uremic syndrome (HUS)

79
Q

Shigellosis diagnosis

A

Culture feces, PMN in feces (indicates invasive infection), enzyme immunoassay, ELISA, PCR

80
Q

Shigellosis tx

A

Supportive - fluid replacement
Amoxicillin, ampicillin

81
Q

What is the bacteria/characteristics?

A

Salmonella; lot of flagella (motile) and fimbrae (attachment)

82
Q

Salmonella does not ferment _____

A

Lactose

83
Q

Salmonella produces _____ from thiosulfate

A

Hydrogen Sulfide (H2S)

84
Q

Salmonella major virulence factors

A
  • Endotoxin (O antigen)
  • Vi antigen (antiphagocytic capsular polysaccharide)
  • flagellar phase variation
85
Q

____ has flagellar variation and has 2 alternatively expressed H antigen genes

A

Salmonella

86
Q

Salmonella transmission

A

Fecal oral

87
Q

Where does Salmonella invade?

A

M cells in small intestine

88
Q

Salmonella _____ causes most human infections

A

Enterica

89
Q

Salmonella infections

A
  • gastroenteritis
  • enteric fever
  • septicemia/sepsis
  • asymptomatic carriage in gallbladder

Salmonella AGES me

90
Q

Most common salmonella infection; what is it caused by?

A

Gastroenteritis
- Salmonella enteritidis, Salmonella Typhimurium

91
Q

Enteric fever also known as

A

Typhoid fever

92
Q

Enteric fever is caused by:

A

Salmonella Typhi, Salmonella Paratyphi

93
Q

What is septicemia/sepsis

A

Systemic inflammation triggered by the immune response to an infection

94
Q

Septicemia/sepsis may lead to:

A

Osteomyelitis, endocarditis

95
Q

Septicemia/sepsis can be caused by:

A

Salmonella Typhi, Salmonella Paratyphi

96
Q

Most common form salmonellosis

A

Enteritis

97
Q

Salmonella enteritis is caused by eating ____

A

Raw/undercooked poultry and eggs

98
Q

Salmonella enteritis symptoms

A

Non-bloody diarrhea, nausea, vomiting, fever, cramps, myalgia, headache

99
Q

Salmonella enteritis treatment

A

Rehydrate
Abx not recommended
Septicemia should be treated w/ ampicillin, cephalosporins

100
Q

Typhoid fever is caused by:

A

Salmonella typhi

101
Q

Typhoid fever is ____ infection

A

Systemic

102
Q

Typhoid fever symptoms

A

During 2nd week - bacteremia, rash, high fever, tender abdomen, constipation

103
Q

When does S. Typhi colonize the gallbladder?

A

During 2nd week

104
Q

In the 3rd/4th week of typhoid fever, what happens?

A

Intestinal hemorrhage, may perforate

105
Q
A

Typhoid fever rash - rose spots

106
Q

True or false: asymptomatic carriers of typhoid are not infectious

A

False (Ex. typhoid Mary)

107
Q

True or false: asymptomatic carriers of typhoid should be treated with antibiotics

A

True - 4-6 weeks

108
Q

Typhoid fever diagnosis

A

Blood or bone marrow culture

109
Q

Tx of typhoid fever

A

Antibiotics (Ceftriaxone, azithromycin)

110
Q

When is S. Typhi vaccine given?

A

To travelers, lab workers, high risk situations

111
Q

What forms of S. Typhi vaccines exist?

A

Inactivated shot; Attenuated (live) oral

112
Q

Yersinia entercolitica is part of what family?

A

Enterobacteriaceae (same as E. coli, Shigella, Salmonella)

113
Q

Yersinia entercolitica is distantly related to:

A

Yersinia pestis

114
Q

Yersinia entercolitica is most common in

A

Children

115
Q

Yersinia pestis order

A

Enterbacteriales

116
Q

True or false: Yersinia pestis is an enteric pathogen

A

False

117
Q

Yersinia pestis is gram ____ and shape ______

A

Gram negative; coccobacillus (fat rod)

118
Q

Yersinia pestis causes:

A

Plague (black death)

119
Q

Yersinia pestis is responsible for what types of plagues? (2)

A
  • urban plague (transmitted by fleas/aerosol inhalation)
  • sylvatic plague (wild animals)
120
Q

Yersinia pestis is endemic to:

A

U.S. (rural southwest states)

121
Q

Forms of plague

A
  • bubonic plague
  • pneumonic plague
  • septicemic plague
122
Q

Bubonic plague is transmitted by ____ and causes ____

A

flea bite (Y. pestis)
lymphadenopathy, high fever

123
Q

What is pneumonic plague?

A

Bacteria (Y. pestis) spread to lungs via aerosol –> pneumonia

124
Q

Septicemic plague is spread to

A

Blood

125
Q

Bubonic plague - where does swelling occur

A

At lymph nodes

126
Q

Sporatic sylvatic plague is usually:

A

Bubonic

127
Q

Pneumonia plague can lead to:

A

Plague gangrene

128
Q

____ causes cholera

A

Vibrio cholerae

129
Q

Vibrio cholerae is gram ____ and shaped like:

A

Gram negative; comma shaped

130
Q

V. cholerae _____ epidemic serotypes produce toxin

A

01 and 0139

131
Q

Vibrio cholerae transmission

A

Fecal oral

132
Q

Cholera toxin structure

A

AB structure

133
Q

Is cholera toxin heat labile/stable?

A

Heat labile

134
Q

Cholera toxin causes uncontrolled activation of ____ leading to ____

A

adenylate cyclase; osmotic imbalance

135
Q

Cholera toxin - steps of mechanism of pathogenesis (5)

A
  1. A subunit activates G protein
  2. uncontrolled stimulation of adenylate cyclase (cell membrane)
  3. stimulates cAMP production from ATP
  4. cAMP activates protein kinase A
  5. osmotic imbalance
136
Q

Osmotic imbalance in cholera leads to:

A

Dehydration and electrolytes loss

137
Q

Main symptom of cholera

A

Profuse watery diarrhea - rice water stools

138
Q

Cholera tx

A

Rehydration (IV, oral)

139
Q

Cholera prevention

A

Sanitation

140
Q

____ is acquired through open wounds or eating raw shellfish

A

Vibrio vulnificus

141
Q

Vibrio vulnificus is associated with ____ wounds

A

Gangrenous

142
Q

Vibrio vulnificus can cause bacteremia, leading to _____ and a ___ mortality

A

Septic shock; 50%

143
Q

Vibrio parahaemolyticus can be acquired through>

A

Ingesting raw/improperly cooked shellfish

144
Q
A

Campylobacter jejuni
Gram negative curved rods in pairs

145
Q

Campylobacter jejuni is highly associated with:

A

Poultry

146
Q

Assume that all chicken is contaminated with:

A

Salmonella and Campylobacter (and others)

147
Q

Helicobacter pylori colonizes the gut via:

A

Adhesins that mediate attachment to gastric mucosa

148
Q

H. pylori produces ____ which is great for testing, and increases pH of gastric microenvironment

A

Urease

149
Q

Clinical diseases caused by H. pylori

A
  • chronic gastritis
  • duodenal ulcer
  • gastric peptic ulcer
  • gastric carcinoma
150
Q

H. pylori is found in ___ of duodenal ulcers and ____ of gastric ulcers

A

95%; 85%

151
Q

H. pylori transmission

A

Fecal oral

152
Q

H. pylori can be diagnosed using:

A

Urease tests (gastric biopsy and breath test)

153
Q

What is the H. pylori breath test?

A
  • drink 13C-Urea
  • if urease is produced then H. pylori is present because 13CO2 will be breathed out
154
Q

How is H. pylori treated?

A
  • antibiotics (clarithromycin and amoxicillin; clarithomycin and metronidazole)
  • Proton pump inhibitors (PPI)
155
Q

What do proton pump inhibitors do (H. pylori)?

A
  • suppresses gastric juice production
  • concentrate and stabilize antibiotics
156
Q

Enterobacter are mostly ____ infections

A

Hospital acquired

157
Q

True or false: antibiotic resistance is a serious problem with hospital acquired infections of Enterobacter

A

True

158
Q

Proteus mirabilis is a ____ producer

A

Urease

159
Q

Proteus mirabilis hydrolyzes urea to make ____, which can lead to formation of ____

A

ammonia; kidney stones

160
Q

True or false: Serratia is a nosocomial infection

A

True

161
Q

Which bacteria produces a bright red pigment?

A

Serratia

162
Q

Serratia grows well on:

A

Moist environments
“Bloody” bread

163
Q

P. aeruginosa produces pigments, which are:

A

Pyocyanin (blue), fluorescein (yellow)
Together looks green

164
Q

P. aeruginosa virulence factors

A
  • abundant anti-phagocytic capsule (slime)
  • multiple antibiotic resistance
165
Q

Why are cystic fibrosis patients more susceptible to P. aeruginosa infections?

A

Alteration of respiratory epithelium facilitates colonization

166
Q

Klebsiella pneumoniae has a prominent ____

A

Capsule

167
Q

Where is Klebsiella pneumoniae found?

A

Normal flora GI tract

168
Q

Klebsiella pneumoniae associated diseases

A

Lobar pneumonia in compromised patients

169
Q

What is carbapenem?

A

Group of beta lactam antibiotics

170
Q

True or false: Klebsiella pneumoniae is not known to be resistant to any antibiotics

A

False - it is a multi-drug resistance Gram-negative bacteria

171
Q

Klebsiella pneumoniae produces _____ which confers resistance to most beta lactam antibiotics

A

Extended spectrum beta lactamases (ESBLs)

172
Q

Carbapenem resistant enterobacteriaceae (CRE) are resistant to:

A

Nearly all available antibiotics

173
Q

Family ____ is most common cause of CRE

A

Enterobacteriaceae
(Most commonly Klebsiella pneumoniae)

174
Q

Some CRE infection cases must now use ____ as an antibiotic, but it is a last resort due to potential kidney toxicity

A

Colistin

175
Q

True or false: there are many new drugs for gram negative bacilli

A

False - few new ones

176
Q

______ is the most common bacteria in Class A carbapenemase

A

Enterobacteriaceae

177
Q

Class A carbapenemase confers resistance to:

A

All Beta lactams

178
Q

E. coli UTI treatment

A

septra (trimethoprim-sulfamethoxazole)

DEN 7102 Micro & Immuno Concepts (26 decks)

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