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House Microbiology > Bacterial infections of the lower GIT > Flashcards

Bacterial infections of the lower GIT Flashcards

1
Q

The Intestinal Microflora

The intestinal microflora may prevent infection by _______________

A

interfering with pathogens

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2
Q

The Intestinal Microflora

The flora includes low populations of potentially pathogenic organisms such
as ____________

A

Clostridium difficile

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3
Q

The Intestinal Microflora

_________ that upset the balance of the normal flora can favor both infection
by _______________ and _______________

A

Antibiotics

exogenous pathogens and overgrowth by endogenous pathogens

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4
Q

The intestinal microflora

If the bowel wall is _______, enteric bacteria can escape into the _______ and cause ________ and _________

A

breached

peritoneum

peritonitis and abscesses.

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5
Q

Transmission

Most GIT infections are transmitted by _________ and __________ – ___________ route

A

food and water contamination

fecal oral

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6
Q

Transmission

fecal oral route

This Fecal-oral cycle can be broken by: -Proper ________
-________ of drinking water
-______ food preparation and storage

A

sewage disposal

Disinfection

Proper

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7
Q

Pathogenicity

The bacterial flora changes only along the length of the GIT with regard to the mucosal surface
T/F

A

F

The bacterial flora changes not only along the length of the GIT but also cross- sectionally with regard to the mucosal surface

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8
Q

Pathogenicity

Bacteria occupy the _____, overlie the _________, and adhere to the mucosa.

Penetration of bacteria through the mucosal surface is ____________-

________ in the stomach kills most organisms that are swallowed

A

lumen

epithelial cells

an abnormal event

Gastric acid

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9
Q

Pathogenicity

Penetration of bacteria through the mucosal surface is an abnormal event -
_____,_____,_____ invade in this way.

A

Shigella, Salmonella, and Campylobacter

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10
Q

Pathogenicity

Reduced or absent gastric acid have a (low or high?) incidence of bacterial colonization in the _______________ and are more susceptible to ______ disease

A

High

upper small bowel

diarrheal

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11
Q

Pathogenicity

__________ is a key element in suppressing the flora of the upper bowel

A

Peristalsis

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12
Q

Pathogenicity

Production of ______,_________ etc by normal flora _______ the normal populations and prevents _________________

A

bacteriocins, fatty acids

stabilizes

implantation of pathogens.

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13
Q

Bacterial Diarrheas

Enterotoxigenic bacteria, such as _________ and enterotoxigenic ________ strains, colonize the upper bowel and cause _______ diarrhea by producing __________ that stimulates mucosal cells to _________ via an increase in intracellular AMP

A

Vibrio cholerae

Escherichia coli

watery; an enterotoxin

secrete fluid

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14
Q

Bacterial Diarrheas

Invasive Diarrheas: Invasive bacteria, such as ________ and _________, tend to ______ the intestinal mucosa.

A ———,———- diarrheal stool with ________ is produced

A

Shigella and Campylobacter

penetrate

bloody, mucoid

inflammatory exudate

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15
Q

Bile has antibacterial properties

T/F

A

T

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16
Q

Bacterial Diarrheas

Invasive bacteria act primarily in the ______ (Shigella and Campylobacter) or ________ (Salmonella)

The stool in these diseases may contain _______

A

colon

lower ileum

blood

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17
Q

Bacterial Diarrheas

Colitis is marked by ________ at ______ (_______)

A

painful straining

Stool

(tenesmus).

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18
Q

Presentation

Symptoms of enteritis can start anywhere from a ______ to a _______ after infection.

Symptoms may include:
________
______ and ______
loss of appetite
abdominal cramps and pain
pain, bleeding, or ______ discharge from the ________
fever

A

few hours

diarrhea
nausea and vomiting

mucus-like

rectum

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19
Q

The most common type of gastroenteritis is ???

A

Food poisoning

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20
Q

Food poisoning

Acquired from __________________ that is _______________.

A

ingestion of food or water

contaminated with bacteria

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21
Q

Food poisoning

The bacteria can enter the food supply in a number of ways, including:

 improper _______
 poor _______ during poultry and meat processing

A

food handling

hygiene

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22
Q

Food poisoning

The foods most often associated with food poisoning are:
 _______________
____________ milk
 fresh ______

A

raw poultry and meat

unpasteurized

produce

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23
Q

Commonly implicated bacteria in food poisoning

List 7

______ species

A

Salmonella
Escherichia coli (E. coli)
Staphylococcus aureus (S. aureus)
Campylobacter jejuni (C. jejuni)
Shigella
Yersinia enterocolitica (Y. enterocolitica)

Bacillus

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24
Q

Staphylococcal Food Poisoning

Staphylococcus aureus enterotoxin is a _________

The staphylococcal enterotoxin also has a direct effect on the _____________________

A

superantigen

vomiting center in the brain

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25
Q

Staphylococcal Food Poisoning

Diarrhea is a typical feature of this kind of food poisoning

T/F

A

F

Diarrhea is not a typical feature of this kind of food poisoning

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26
Q

Bacillus cereus

B. cereus :

(Spore or Non- spore?) -forming bacillus that associated with __________.

Ingestion of bacterial exotoxin produces (mild or severe?) symptoms

A

Spore

reheated fried rice

Mild

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27
Q

Clostridium perfringens

This species is a (common or rare?) member of the ______ normal flora

A

Common

colonic

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28
Q

Clostridium perfringens

gram- ________

______-shaped

_______-forming

(Aerobic or anaerobic?) bacterium

(tolerant or intolerant?) of high and low temperatures

A

positive

rod

endospore; anaerobic

Tolerant

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29
Q

Clostridium perfringens

At (low or high?) temperatures, the bacteria can form _______ that will germinate (slowly or rapidly?) in foods or within the intestine

A

High; endospores

rapidly

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30
Q

Clostridium perfringens

Food poisoning by type ___ strains is common.

This strain always produces ________

A

A

An enterotoxin

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31
Q

Clostridium perfringens

Food poisoning

(Mild or Severe?) foodborne disease that is associated with ________________ and other foods
A more severe form of the illness, called ———— or _______, causes _______, pain, vomiting, and ______

A

Mild

undercooked meats

pig-bel or enteritis necroticans

hemorrhaging; bloating

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32
Q

Clostridium perfringens

————- of the intestines may result

A

Gangrene

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33
Q

Diagnosis of C.perfringes

Diagnosis involves detecting the C. perfringens ____________ in _______ using either molecular biology techniques (PCR detection of the toxin gene) or immunology techniques (ELISA)

The ________ may also be detected in foods or in fecal samples.

A

toxin in stool samples

bacteria itself

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34
Q

Treatment of C.perfringes

includes ________ therapy, _______ replacement, and _________

A

rehydration

electrolyte

intravenous fluids.

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35
Q

Shigellosis

When gastrointestinal illness is associated with the _____-shaped, gram- ______ bacterium shigella Spp.

A

rod

negative

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36
Q

Shigellosis

Bacillary dysentery, or shigellosis

Infections can be caused by

S._______, S. _______, S. _______, and/or S.
_______ that colonize the GI tract

Shigellosis can be spread from ________________ or _______________

A

dysenteriae

S. _______, S. _______, and/or S.
_________

hand to mouth or through contaminated food and water

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37
Q

Shigellosis

invade ______________ targets epithelium and structures of the ________ in the intestine which may become _________ and cause _______

A

intestinal epithelial cells

Peyer’s patches; ulcerated

loss of fluid

38
Q

Shigellosis

severe cases may result in ____________,_________,__________ and ____

A

ulceration of the mucosa, dehydration, and rectal bleeding, HUS

39
Q

Shigelliosis

Step 1: shigella __________

Step 2 : Shigella —————

Step 3 : Shigella invade __________, thus ________________

Step 4: ________ forms as ———— are ________ by the infection .

A

enter an epithelial cell

multiply inside the cell

neighboring epithelial cells; avoiding immune defenses

an abscess; epithelial cells ; killed off

40
Q

Shigelliosis

The bacteria often spread in the blood stream

T/F

A

F

rarely

41
Q

Salmonella and campylobacter

(Low or High?) -level contamination with salmonella or campylobacter spp. May result in a food poisoning-like syndrome .

But, these species are more typically associated with ________ caused by bacterial invasion of the intestinal mucosa

A

High

enteritis

42
Q

Salmonella and campylobacter

Salmonella species are a (rare or common?) cause of food poisoning

A

Common

43
Q

Salmonellosis

Two species, S._______ and S.________, cause disease in humans, but S.
__________ is the most common.

Mortality (_____%) due to _______ caused by endotoxin

A

enterica

bongori

enterica

<1

septic shock

44
Q

Salmonellosis

Step 1:salmonella _______

Step 2: salmonella ____________

Step3: salmonella ________ in mucosa cells , in there, the Inflammatory response results in _______ .

Occasionally, the bacteria, __________________ and ______________

A

enter an epithelial cell

multiply within vesicle inside the cell

multiply; diarrhea

cross the epithelial cell membrane and enter the bloodstream and lymphatic system

45
Q

Typhoid Fever

Certain serotypes of S.____________ , primarily serotype _______ (S. _________) but also ______, cause a more severe type of salmonellosis called typhoid fever

This serious illness, which has an untreated mortality rate of ______%, causes (low or high?) high fever, body aches, headache, nausea, lethargy, and a possible _____

A

enterica; Typhi; Typhi; Paratyphi

10; high; rash

46
Q

Typhoid Fever

The main site of attack by the organism is the _______, where the salmonellae cause _________

Bacteria spread throughout body in _______, cause ________

Diarrhea is uncommon in (early or late?) stage

A

lower ileum; mucosal ulceration

phagocytes; systemic infection

Early

47
Q

Campylobacter Gastroenteritis

Campylobacter

gram- ________

______ or ________ bacteria.

They may have _______ flagella

A

negative

spiral or curved

one or two

48
Q

Campylobacter Gastroenteritis

Campylobacter jejuni gastroenteritis, a form of _________, is a widespread illness that is caused by Campylobacter jejuni

The primary route of transmission is through ________ that becomes contaminated during ________

A

campylobacteriosis

poultry; slaughter

49
Q

Campylobacter Gastroenteritis

Transmission

___________________________ in turn contaminates cooking surfaces, utensils, and other foods

—————— or _____________ are also potential vehicles of transmission

A

Handling of the raw chicken

Unpasteurized milk or contaminated water

50
Q

Campylobacter gastroenteritis

The illness is ________ and includes fever, diarrhea, cramps, vomiting, and sometimes _______

More serious signs and symptoms, such as ________,________ pancreatitis, cholecystitis, and hepatitis, sometimes occur

A

self-limiting; dysentery

bacteremia, meningitis,

51
Q

Campylobacter gastroenteritis

It has also been associated with _______ conditions such as _______,__________

The virulence in many strains is the result of _________ production and the presence of ———————— toxin - (a _______ ) that (reversibly or irreversibly?) damages host cell DNA

A

autoimmune

Guillain- Barré syndrome, HUS

hemolysin

Campylobacter cytolethal distending

DNase; irreversibly

52
Q

Campylobacter gastroenteritis

These bacteria should be cultured on selective medium (such as ______ CV, __________ medium, or __________________ agar) and incubated under __________ conditions for at least _____ hours at ____°C.

A

Campy ; charcoal selective

cefaperazone charcoal deoxycholate

microaerophilic

72

42

53
Q

Yersinia Gastroenteritis

Y. _____________

Can reproduce at ___°C

Usually transmitted in ______ and _______

A

enterocolitica

4

meat and milk

54
Q

Cholera

_____ cholerae serotypes that produce cholera toxin

Toxin causes host cells to secrete ______,_____, and ______ result in diarrheal disease.

A

Vibrio

Cl–, HCO–, and water,

55
Q

Cholera

Vibrio cholerae serotype _____

a gram-_______

(Non-flagellated or flagellated?) bacterium

shape of a _________(vibrio)

A

O1; negative

Flagellated

curved rod

56
Q

Cholera

According to the CDC, cholera causes an estimated ————- cases and ______ deaths each year

A

3 to 5 million; 100,000

57
Q

Cholera

V. cholerae is killed by __________, relatively (small or large?) doses are needed for a few microbial cells to survive to reach the intestines and cause infection

A

stomach acid

Large

58
Q

Cholera

The motile cells travel through the _________ of the intestines, where they attach to ______ and release cholera ________.

The toxin is —————— with activity through ___________

A

mucous layer

epithelial cells

enterotoxin

an A-B toxin

adenylate cyclase

59
Q

Cholera

Within the intestinal cell, cyclic AMP (cAMP) levels ____ease, which activates a __________ and results in the release of ions into the intestinal lumen

This increase in ________ in the lumen which leads to _____________

As they both leave the body, it causes rapid _________ and __________ imbalance

A

incr; chloride channel

osmotic pressure

water also entering the lumen

dehydration and electrolyte

60
Q

Cholera

Diarrhea is so profuse that it is often called “___________,” and patients are placed on ______________ to monitor the fluid loss

A

rice water stool

cots with a hole in them

61
Q

Cholera – laboratory diagnosis

_____ sample and culturing for Vibrio

The bacteria are oxidase _______ and show (lactose or non-lactose?) fermentation on ________ agar

_______________ (TCBS) agar, a selective and differential media for Vibrio spp., which produce a distinct _____ colony.

A

stool; positive

non-lactose; maconkey

thiosulfate citrate bile salts sucrose

yellow

62
Q

Other vibro pathogens

V. _________ is associated with consumption of contaminated ______ and causes gastrointestinal illness with signs and symptoms such as watery diarrhea, nausea, fever, chills, and abdominal cramps.

A

parahemolyticus

seafood

63
Q

Other vibro pathogens
V. parahemolyticus

The bacteria produce a heat-_______ hemolysin, leading to _____ and possible disseminated disease

It also sometimes causes _____ infections.

A

stable

dysentery

wound

64
Q

V. parahemolyticus is diagnosed using cultures from _____,_______, or _______

A

blood, stool, or a wound

65
Q

Other vibrio pathogens

Vibrio ________, _______ _______ and ______________________

A

vulnificus

Aeromonas hydrophila

Plesiomonas shigelloides

66
Q

Systemic complications of cholera

Despite invasion, bacteria that cause infective diarrhea rarely reach the systemic circulation.

T/F

A

T

67
Q

Cholera

Gastroenteritis is often _______, and the care is supportive to control symptoms and prevent ______.

A

self-limiting

dehydration

68
Q

Colitis

_______ colitis
________ colitis
_________ disease
_________ colitis
__________ colitis

A

Infective
Ischemic colitis
Inflamatory bowel disease
Pseudomembranous colitis
Microscopic colitis

69
Q

Infective colitis

_______
_________
________
__________

A

Campylobacter
Shigella
E. Coli
Salmonella

70
Q

Colitis

The large-bowel pathogens (the major ones being ______ and __________ ) are invasive organisms and cause the clinical syndrome known as _________

A

Shigella and Campylobacter

dysentery

71
Q

Colitis

Involvement of the colon leading to a characteristic rectal pain - ________

A

tenesmus

72
Q

Colitis

Although the fecal effluent may be _______ at first, by the second or third day of illness the stool is _____ and often _______ or _______

Microscopic examination reveals abundant ————- and ______

A

watery

scanty

bloody or mucoid

erythrocytes and leukocytes.

73
Q

Treatment of gastroenteritis

Rehydration – ___ and sometimes ______

For many cases of bacterial gastroenteritis, only ________ treatment (for fever, diarrhea…) is required.

_________ are not usually recommended as they have __________, may cause ______ and overuse increases the risk of _________ developing.

A

oral; intravenous

symptomatic

Antibiotics; no effect on viral infections

side effects; resistant bacteria

74
Q

Treatment of gastroenteritis

Antibiotics may be recommended in particularly ______ cases of gastroenteritis, or if a _____________________________

A

severe

specific bacteria has been identified as the cause.

75
Q

E.Coli gastroenteritis

The gram- ________, _____ Escherichia coli is a (common or rare?) member of the normal microbiota of the colon

A

negative

rod; common

76
Q

E.Coli gastroenteritis

Most strains are helpful commensal bacteria

T/F

A

T

77
Q

E.Coli gastroenteritis

Some are pathogenic and may cause dangerous diarrheal disease

The pathogenic strains have additional virulence factors such as ___________ that promote colonization of the colon or may produce _____

A

type 1 fimbriae ; toxins

78
Q

E.Coli gastroenteritis

symptoms include ________ and _______

Though it usually resolves after ————, it can sometimes (5-10% of infections) lead to ___________, which can result in ________ if untreated

A

bloody diarrhea and vomiting

a few days

hemolytic uremic syndrome

kidney failure

79
Q

E.coli

Virulence factors are transferred by - ____________ transfer

People usually contract E. coli through ______________________________

A

horizontal gene

ingestion of water contaminated with human or
animal faeces

80
Q

E. coli Gastroenteritis

Certain strains of E coli cause diarrheal disease by elaborating enterotoxins These strains produce two types of enterotoxin

One, heat-______ toxin, is similar in structure and in its mechanism of action to _______ toxin

The second, heat- ______ toxin, appears to act via _________

A

labile; cholera

stable

guanylate cyclase

81
Q

Entero________ E coli strains are the most common cause of travelers’ diarrhea

Occurs as _____________ and ____________ in nurseries

A

toxigenic

traveler’s diarrhea and epidemic diarrhea

82
Q

E. coli Gastroenteritis

Enterohemorrhagic strains such as E. coli _________ produce _____ toxin

A

O157:H7

Shiga

83
Q

Recognized pathogenic groups of E. coli

  1. Enterotoxigenic E. coli (ETEC), also known as _________, causes diarrheal illness and is common in less developed countries

Uses a heat—______enterotoxin similar to _________, and adhesins called _______________ that help the bacteria to _______________________

A

traveler’s diarrhea,

Labile; cholera toxin

colonization factors

attach to the intestinal wall

84
Q

Recognized pathogenic groups of E. coli 1. Enterotoxigenic E. coli (ETEC)

Some strains of ETEC also produce heat-labile toxins

The disease is usually relatively _______ and ________
Diagnosis - ______

A

mild and self-limiting

culturing

85
Q

Enteroinvasive E. coli (EIEC)

similar to ________

carries a (small or large?) plasmid that is involved in ____________

Symptoms = diarrhea, chills, cramps, malaise, fever, and dysentery

_______ and _______ testing can be used for diagnosis

A

shigellosis

Large

epithelial cell penetration

Culturing and PCR

86
Q

Enteropathogenic E. coli (EPEC)

can cause a _________ diarrhea, especially in ______ and those in less developed countries

Fever, vomiting, and diarrhea can lead to severe dehydration

A

potentially fatal ; infants

87
Q

Enteropathogenic E. coli (EPEC)

Inject a protein (_____) that _________________________ and triggers ______________________
from ________ to __________

The protein also happens to be the ______ for _____, a surface protein produced by ———-, thereby allowing E. coli to ________________

.
diagnosis involves culturing and PCR

A

Tir

attaches to the surface of the intestinal epithelial cells

rearrangement of host cell actin

microvilli to pedestals.

receptor; Intimin; EPEC

“sit” on the pedestal

88
Q

enterohemorrhagic E. coli (EHEC)

Most _______ form

strain _______ has been responsible for several recent outbreaks

A

dangerous; O157:H7

89
Q

enterohemorrhagic E. coli (EHEC)

O and H refer to _________ that contribute to pathogenicity and trigger a host immune response

“O” refers to the ______ of the _______ and the “H” refers to the ________

also produces a ______-like toxin

A

surface antigens

O-side chain ; lipopolysaccharide

flagella

Shiga-like

90
Q

enterohemorrhagic E. coli (EHEC)

also produces a Shiga-like toxin – _____toxin (acquired via ________– _________ transfer)

Symptoms include bloody diarrhea with severe cramping, but no ______

A

Vero; transduction ; horizontal gene

fever

91
Q

enterohemorrhagic E. coli (EHEC)

Although it is often self-limiting, it can lead to __________ and profuse bleeding

One possible complication is ______

A

hemorrhagic colitis

HUS

92
Q

enterohemorrhagic E. coli (EHEC)

Diagnosis involves culture, often using ____ with ________ agar to differentiate between E. coli ________, which does not ____________, and other less virulent strains of E. coli that can __________
Serotyping

A

MacConkey; sorbitol

O157:H7; ferment sorbitol

ferment sorbitol.

House Microbiology (93 decks)

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