Infectious Diseases to Gastrointestinal Tract Flashcards
What is the digestive system sometimes referred to?
alimentary or gastrointestinal tract
What is the major route of microbial invasion?
digestive system
What is the main purpose of the digestive system and how is it divided?
provide nutrients to body; divided into upper and lower tracts
What are all intestinal surfaces coated with?
mucus: IgA can be found on most surfaces
What does saliva contain that helps against infectious diseases?
lysozyme and lactoferrin
Why does normal flora not exist in the stomach? What is stomach fluid and bile considered?
because of its extreme acidity. Considered antimicrobials
GALT meaning
Gut-associated lymphoid tissue
Lactoferrin
bacteriocide/ fungicide: high levels of colostrum
What does GALT include?
Tonsils and adenoids in the oral cavity
small areas of lymphoid tissue in the esophagus
Peyer’s patches in the small intestine
What is the most common species that colonizes oral cavity?
streptococcal species
What limits the number of bacteria on mucus membranes in the normal flora of the mouth?
Host limits the #.
Membrane cells are constantly shedding
Why can large numbers of bacteria collect on teeth? what can they form? what is this called
Teeth are non-shedding surface
large numbers of bacteria can collect and for biofilm, masses of bacteria termed dental plaque
What are the predominant organisms of the normal flora in the small intestine?
facultative gram negative bacilli, and some streptococci
Approximately how many bacteria per gram are found in the large intestine normal flora?
10^11 bacteria per gram
What is the high population of bacteria in the large intestine due to?
nutrients in feces
What species predominate the normal flora of the large intestine?
escherichia coli and other enterobacterium
What is the most common cause of UTI’s in women and why?
fecal matter; bad wiping, important source of opportunisitc infections
What is the most common infectious disease of human beings?
dental caries
What % of US population over 65 have lost all their teeth?
47%
What can be said about the symptoms of dental caries?
What are three?
Carie is usually advanced before symptoms arise
throbbing pain, discoloration of teeth, breaking when chewing
What is the most common causative agent for dental caries?
streptococcus mutans (gram positive)
What conditions do streptococcus mutans thrive in?
acidic conditions
What do strep. mutans do with dietary sugars?
produce lactic acid from sugar metabolism
What do strep. mutans do with sucrose?
produce glucans, essential for production of dental caries
How does the cariogenic plaque form in a dental carie?
production of glucans bind organisms together and to tooth
What causes calcium phosphate in teeth to dissolve? what does that cause?
acidic environment, creates pits and fissures for colonization
What are the symptoms of Helicobacter pylori Gastritis? and when do they occur?
belching, vomiting, abdominal pain, tenderness, bleeding, occur when infection is complicated with ulcers or cancer
What is the causative agent of Helicobacter pylori Gastritis? what are the features of it?
helicobacter pylori (gram - bacteria) short spiral microaerophile multiple polar flagella
What is particular about Helicobacter pylori and acidity?
they can survive in extreme acidic conditions and they are able to neutralize the environment that they are in
How do Helicobacter pylori use their flagella?
corkscrew through mucosal lining, inflammatory response begins
How is Helicobacter pylori Gastritis most likely transmitted?
fecal-oral route: maybe flies
What % age of the US population is infected with Helicobacter pylori Gastritis? which group is most affected?
20%, almost 80% of those 75 are infected.
lower socioeconomic groups
What are some preventions and treatment of Helicobacter pylori Gastritis?
no proven prevention measures
infection can usually be eradicated with combined antibiotic treatment
Medication is also used to inhibit production of stomach acid
What are the symptoms of shigellosis?
dysentery (Diarrhea); headache, vomiting, fever, stiff neck, convulsions, joint pain
Who is shigellosis commonly fatal for?
infants in developing countries
What are the four species of shigellosis?
S. flexnuri
S. boydii
S. sonnei
S. dysenterriae
Pathogenesis of S.dysenteriae
produces potent a-b toxin
shiga toxin
acts much like cholera toxin
toxin associated with fatal hemolytic uremic syndrome
What do shiga and cholera toxins cause leading to loss of solutes and thus loss of water? What does the inflammatory response account for?
cause disregulation of cAMP in host cells. inflammatory response accounts for blood
What is the general source of transmission of shigellosis?
generally human source; transmitted fecal-oral route
What does shigellosis have making it not easily killed by stomach acid?
does not have high infecting dose
as few as 10 organisms
What is transmission of shigellosis most often a result of?
overcrowding, also common in day cares and among homosexual men
Is there a vaccine available for shigellosis?
no
What is the most important treatment for shigellosis?
fluid and electrolyte replacement.
What is the drug of choice for shigellosis and what are the newer drugs?
ampicillin is drug of choice, newer penicillins or ciproflaxacin
What are the signs and symptoms of clostridium difficile
diarrhea commending in late antibiotic therapy or even after therapy has stopped. severe cases exhibit abdominal cramps, fever and leukocytosis.
What does the colon gradually slough off loose, membranelike patches calles..
pseudomembranes
What will happen if the condition Clostridium Difficile is not stopped?
perforation of the cecum and death can result
What is the causative agent of clostridium difficile?
gram positive endospore forming rod
What are the virulent factors of c. difficile?
able to superinfect the large intestine when drugs have disrupted the normal biota
produces A and B enterotoxins: cause necrosis in large intestine
What is C. difficile now known as?
a condition called psedomembranous colitis: or antibiotic associated colitis
What is the major cause of diarrhea in hospitals?
C. difficile
community acquired infection have been on the rise in the past few years
What can predispose people to infection?
use of gastric acid inhibitors.
What is the treatment of uncomplicated cases of clostridium difficile?
withdrawal of antibiotics and replacement therapy for lost fluids and electrolytes.
How are more severe infections c. difficile treated?
treated with antibiotics for several weeks until the intestinal biota returns to normal
What are the two types of antibiotics that are used to treat more severe infections of C. difficile and how do they work?
Vancomycin: cell wall synthesis inhibitor for gram +
Fidaxomicin: (approved in 2011) nucleic acid synthesis inhibitor especially effective for clostridium
