Bacterial infections of the lower GIT Flashcards by Iseoluwa Ojo

The Intestinal Microflora

The intestinal microflora may prevent infection by _______________

interfering with pathogens

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The Intestinal Microflora

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

Clostridium difficile

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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

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The intestinal microflora

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

breached

peritoneum

peritonitis and abscesses.

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Transmission

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

food and water contamination

fecal oral

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Transmission

fecal oral route

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

sewage disposal

Disinfection

Proper

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Pathogenicity

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

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Pathogenicity

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

Shigella, Salmonella, and Campylobacter

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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

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Pathogenicity

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

Peristalsis

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Pathogenicity

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

bacteriocins, fatty acids

stabilizes

implantation of pathogens.

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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

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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

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Bile has antibacterial properties

T/F

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Bacterial Diarrheas

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

The stool in these diseases may contain _______

colon

lower ileum

blood

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Bacterial Diarrheas

Colitis is marked by ________ at ______ (_______)

painful straining

Stool

(tenesmus).

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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

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The most common type of gastroenteritis is ???

Food poisoning

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Food poisoning

Acquired from __________________ that is _______________.

ingestion of food or water

contaminated with bacteria

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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

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Food poisoning

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

raw poultry and meat

unpasteurized

produce

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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

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Staphylococcal Food Poisoning

Staphylococcus aureus enterotoxin is a _________

The staphylococcal enterotoxin also has a direct effect on the _____________________

superantigen

vomiting center in the brain

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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

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

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 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 _______________________

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.