Bacterial infections of the lower GIT Flashcards
The Intestinal Microflora
The intestinal microflora may prevent infection by _______________
interfering with pathogens
The Intestinal Microflora
The flora includes low populations of potentially pathogenic organisms such
as ____________
Clostridium difficile
The Intestinal Microflora
_________ that upset the balance of the normal flora can favor both infection
by _______________ and _______________
Antibiotics
exogenous pathogens and overgrowth by endogenous pathogens
The intestinal microflora
If the bowel wall is _______, enteric bacteria can escape into the _______ and cause ________ and _________
breached
peritoneum
peritonitis and abscesses.
Transmission
Most GIT infections are transmitted by _________ and __________ – ___________ route
food and water contamination
fecal oral
Transmission
fecal oral route
This Fecal-oral cycle can be broken by: -Proper ________
-________ of drinking water
-______ food preparation and storage
sewage disposal
Disinfection
Proper
Pathogenicity
The bacterial flora changes only along the length of the GIT with regard to the mucosal surface
T/F
F
The bacterial flora changes not only along the length of the GIT but also cross- sectionally with regard to the mucosal surface
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
lumen
epithelial cells
an abnormal event
Gastric acid
Pathogenicity
Penetration of bacteria through the mucosal surface is an abnormal event -
_____,_____,_____ invade in this way.
Shigella, Salmonella, and Campylobacter
Pathogenicity
Reduced or absent gastric acid have a (low or high?) incidence of bacterial colonization in the _______________ and are more susceptible to ______ disease
High
upper small bowel
diarrheal
Pathogenicity
__________ is a key element in suppressing the flora of the upper bowel
Peristalsis
Pathogenicity
Production of ______,_________ etc by normal flora _______ the normal populations and prevents _________________
bacteriocins, fatty acids
stabilizes
implantation of pathogens.
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
Vibrio cholerae
Escherichia coli
watery; an enterotoxin
secrete fluid
Bacterial Diarrheas
Invasive Diarrheas: Invasive bacteria, such as ________ and _________, tend to ______ the intestinal mucosa.
A ———,———- diarrheal stool with ________ is produced
Shigella and Campylobacter
penetrate
bloody, mucoid
inflammatory exudate
Bile has antibacterial properties
T/F
T
Bacterial Diarrheas
Invasive bacteria act primarily in the ______ (Shigella and Campylobacter) or ________ (Salmonella)
The stool in these diseases may contain _______
colon
lower ileum
blood
Bacterial Diarrheas
Colitis is marked by ________ at ______ (_______)
painful straining
Stool
(tenesmus).
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
few hours
diarrhea
nausea and vomiting
mucus-like
rectum
The most common type of gastroenteritis is ???
Food poisoning
Food poisoning
Acquired from __________________ that is _______________.
ingestion of food or water
contaminated with bacteria
Food poisoning
The bacteria can enter the food supply in a number of ways, including:
improper _______
poor _______ during poultry and meat processing
food handling
hygiene
Food poisoning
The foods most often associated with food poisoning are:
_______________
____________ milk
fresh ______
raw poultry and meat
unpasteurized
produce
Commonly implicated bacteria in food poisoning
List 7
______ species
Salmonella
Escherichia coli (E. coli)
Staphylococcus aureus (S. aureus)
Campylobacter jejuni (C. jejuni)
Shigella
Yersinia enterocolitica (Y. enterocolitica)
Bacillus
Staphylococcal Food Poisoning
Staphylococcus aureus enterotoxin is a _________
The staphylococcal enterotoxin also has a direct effect on the _____________________
superantigen
vomiting center in the brain
Staphylococcal Food Poisoning
Diarrhea is a typical feature of this kind of food poisoning
T/F
F
Diarrhea is not a typical feature of this kind of food poisoning
Bacillus cereus
B. cereus :
(Spore or Non- spore?) -forming bacillus that associated with __________.
Ingestion of bacterial exotoxin produces (mild or severe?) symptoms
Spore
reheated fried rice
Mild
Clostridium perfringens
This species is a (common or rare?) member of the ______ normal flora
Common
colonic
Clostridium perfringens
gram- ________
______-shaped
_______-forming
(Aerobic or anaerobic?) bacterium
(tolerant or intolerant?) of high and low temperatures
positive
rod
endospore; anaerobic
Tolerant
Clostridium perfringens
At (low or high?) temperatures, the bacteria can form _______ that will germinate (slowly or rapidly?) in foods or within the intestine
High; endospores
rapidly
Clostridium perfringens
Food poisoning by type ___ strains is common.
This strain always produces ________
A
An enterotoxin
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 ______
Mild
undercooked meats
pig-bel or enteritis necroticans
hemorrhaging; bloating
Clostridium perfringens
————- of the intestines may result
Gangrene
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.
toxin in stool samples
bacteria itself
Treatment of C.perfringes
includes ________ therapy, _______ replacement, and _________
rehydration
electrolyte
intravenous fluids.
Shigellosis
When gastrointestinal illness is associated with the _____-shaped, gram- ______ bacterium shigella Spp.
rod
negative
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 _______________
dysenteriae
S. _______, S. _______, and/or S.
_________
hand to mouth or through contaminated food and water
Shigellosis
invade ______________ targets epithelium and structures of the ________ in the intestine which may become _________ and cause _______
intestinal epithelial cells
Peyer’s patches; ulcerated
loss of fluid
Shigellosis
severe cases may result in ____________,_________,__________ and ____
ulceration of the mucosa, dehydration, and rectal bleeding, HUS
Shigelliosis
Step 1: shigella __________
Step 2 : Shigella —————
Step 3 : Shigella invade __________, thus ________________
Step 4: ________ forms as ———— are ________ by the infection .
enter an epithelial cell
multiply inside the cell
neighboring epithelial cells; avoiding immune defenses
an abscess; epithelial cells ; killed off
Shigelliosis
The bacteria often spread in the blood stream
T/F
F
rarely
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
High
enteritis
Salmonella and campylobacter
Salmonella species are a (rare or common?) cause of food poisoning
Common
Salmonellosis
Two species, S._______ and S.________, cause disease in humans, but S.
__________ is the most common.
Mortality (_____%) due to _______ caused by endotoxin
enterica
bongori
enterica
<1
septic shock
Salmonellosis
Step 1:salmonella _______
Step 2: salmonella ____________
Step3: salmonella ________ in mucosa cells , in there, the Inflammatory response results in _______ .
Occasionally, the bacteria, __________________ and ______________
enter an epithelial cell
multiply within vesicle inside the cell
multiply; diarrhea
cross the epithelial cell membrane and enter the bloodstream and lymphatic system
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 _____
enterica; Typhi; Typhi; Paratyphi
10; high; rash
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
lower ileum; mucosal ulceration
phagocytes; systemic infection
Early
Campylobacter Gastroenteritis
Campylobacter
gram- ________
______ or ________ bacteria.
They may have _______ flagella
negative
spiral or curved
one or two
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 ________
campylobacteriosis
poultry; slaughter
Campylobacter Gastroenteritis
Transmission
___________________________ in turn contaminates cooking surfaces, utensils, and other foods
—————— or _____________ are also potential vehicles of transmission
Handling of the raw chicken
Unpasteurized milk or contaminated water
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
self-limiting; dysentery
bacteremia, meningitis,
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
autoimmune
Guillain- Barré syndrome, HUS
hemolysin
Campylobacter cytolethal distending
DNase; irreversibly
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.
Campy ; charcoal selective
cefaperazone charcoal deoxycholate
microaerophilic
72
42
Yersinia Gastroenteritis
Y. _____________
Can reproduce at ___°C
Usually transmitted in ______ and _______
enterocolitica
4
meat and milk
Cholera
_____ cholerae serotypes that produce cholera toxin
Toxin causes host cells to secrete ______,_____, and ______ result in diarrheal disease.
Vibrio
Cl–, HCO–, and water,
Cholera
Vibrio cholerae serotype _____
a gram-_______
(Non-flagellated or flagellated?) bacterium
shape of a _________(vibrio)
O1; negative
Flagellated
curved rod
Cholera
According to the CDC, cholera causes an estimated ————- cases and ______ deaths each year
3 to 5 million; 100,000
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
stomach acid
Large
Cholera
The motile cells travel through the _________ of the intestines, where they attach to ______ and release cholera ________.
The toxin is —————— with activity through ___________
mucous layer
epithelial cells
enterotoxin
an A-B toxin
adenylate cyclase
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
incr; chloride channel
osmotic pressure
water also entering the lumen
dehydration and electrolyte
Cholera
Diarrhea is so profuse that it is often called “___________,” and patients are placed on ______________ to monitor the fluid loss
rice water stool
cots with a hole in them
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.
stool; positive
non-lactose; maconkey
thiosulfate citrate bile salts sucrose
yellow
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.
parahemolyticus
seafood
Other vibro pathogens
V. parahemolyticus
The bacteria produce a heat-_______ hemolysin, leading to _____ and possible disseminated disease
It also sometimes causes _____ infections.
stable
dysentery
wound
V. parahemolyticus is diagnosed using cultures from _____,_______, or _______
blood, stool, or a wound
Other vibrio pathogens
Vibrio ________, _______ _______ and ______________________
vulnificus
Aeromonas hydrophila
Plesiomonas shigelloides
Systemic complications of cholera
Despite invasion, bacteria that cause infective diarrhea rarely reach the systemic circulation.
T/F
T
Cholera
Gastroenteritis is often _______, and the care is supportive to control symptoms and prevent ______.
self-limiting
dehydration
Colitis
_______ colitis
________ colitis
_________ disease
_________ colitis
__________ colitis
Infective
Ischemic colitis
Inflamatory bowel disease
Pseudomembranous colitis
Microscopic colitis
Infective colitis
_______
_________
________
__________
Campylobacter
Shigella
E. Coli
Salmonella
Colitis
The large-bowel pathogens (the major ones being ______ and __________ ) are invasive organisms and cause the clinical syndrome known as _________
Shigella and Campylobacter
dysentery
Colitis
Involvement of the colon leading to a characteristic rectal pain - ________
tenesmus
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 ______
watery
scanty
bloody or mucoid
erythrocytes and leukocytes.
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.
oral; intravenous
symptomatic
Antibiotics; no effect on viral infections
side effects; resistant bacteria
Treatment of gastroenteritis
Antibiotics may be recommended in particularly ______ cases of gastroenteritis, or if a _____________________________
severe
specific bacteria has been identified as the cause.
E.Coli gastroenteritis
The gram- ________, _____ Escherichia coli is a (common or rare?) member of the normal microbiota of the colon
negative
rod; common
E.Coli gastroenteritis
Most strains are helpful commensal bacteria
T/F
T
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 _____
type 1 fimbriae ; toxins
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
bloody diarrhea and vomiting
a few days
hemolytic uremic syndrome
kidney failure
E.coli
Virulence factors are transferred by - ____________ transfer
People usually contract E. coli through ______________________________
horizontal gene
ingestion of water contaminated with human or
animal faeces
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 _________
labile; cholera
stable
guanylate cyclase
Entero________ E coli strains are the most common cause of travelers’ diarrhea
Occurs as _____________ and ____________ in nurseries
toxigenic
traveler’s diarrhea and epidemic diarrhea
E. coli Gastroenteritis
Enterohemorrhagic strains such as E. coli _________ produce _____ toxin
O157:H7
Shiga
Recognized pathogenic groups of E. coli
- 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 _______________________
traveler’s diarrhea,
Labile; cholera toxin
colonization factors
attach to the intestinal wall
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 - ______
mild and self-limiting
culturing
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
shigellosis
Large
epithelial cell penetration
Culturing and PCR
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
potentially fatal ; infants
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
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
enterohemorrhagic E. coli (EHEC)
Most _______ form
strain _______ has been responsible for several recent outbreaks
dangerous; O157:H7
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
surface antigens
O-side chain ; lipopolysaccharide
flagella
Shiga-like
enterohemorrhagic E. coli (EHEC)
also produces a Shiga-like toxin – _____toxin (acquired via ________– _________ transfer)
Symptoms include bloody diarrhea with severe cramping, but no ______
Vero; transduction ; horizontal gene
fever
enterohemorrhagic E. coli (EHEC)
Although it is often self-limiting, it can lead to __________ and profuse bleeding
One possible complication is ______
hemorrhagic colitis
HUS
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
MacConkey; sorbitol
O157:H7; ferment sorbitol
ferment sorbitol.
