Terms to know Flashcards
(39 cards)
Tenesmus
- a continual or recurrent inclination to evacuate the bowels,
- caused by disorder of the rectum or other illnesses.
Gastroenteritis
- known as infectious diarrhoea and gastro; inflammation of the gastrointestinal track the stomach and small intestines
- Symptoms: diarrhea, vomiting, abdominal pai, fever, lack of energy.
- lasts less then 2 weeks
Facultative Ex:
occuring optimally in response to circumstances rather than by nature
Ex: Facultative Anaerobe
Facultative anaerobe
an organism that makes ATP by aerobic respiration if oxygen is present, however is capable of switching to fermentation if oxygen is absent.
(H2S+) Hydrogen Sulfide
- It is a colorless chalcogen hydride gas with the characteristic foul odor of rotten eggs. It is very poisonous, corrosive, and flammable.
- Hydrogen sulfide is often produced from the microbial breakdown of organic matter in the absence of oxygen gas, such as in swamps and sewers; this process is commonly known as anaerobic digestion which is done by sulfate-reducing microorganisms.
Opportunistic Infection
-any infection caused by a microorganism that does not normally cause disease in humans;
occurs in persons with abnormally functioning immune systems (as AIDS patients or transplant patients receiving immunosuppressive drugs)
Opportunistic Pathogen
- an organism that exists harmlessly as part of the normal human body environment and does not become a health threat until the body’s immune system fails
Major causes of Opportunistic Infection:
Provide 4 examples;
- Septicemia
- Pneumonia
- Meningitis
- Urinary Tract Infection
Examples of genera that cause “opportunistic” infections:
name 7
- Citrobacter
- Enterobacter
- Escherichia
- Hafnia
- Morganella
- Providencia
- Serratia
Most common Cause of Urinary tract infections
- E. coli
- UTI’s are ascending often from fecal containination
- Proteus: the organism produces a UREASE that degrades urea producing an alkaline urine
Define Urease
a naturally occurring enzyme that hydrolyzes urea into ammonium carbonate.
Urease Positive
(Urease Test)
Urease test helps for the identification of Proteus species (urease positive) and to differenitate it from other non-lactose fermenting members of the Enterobacteriaceae family.
Urease test is used for the presumptive evidence of the presence of Helicobacter pylori in tissue biopsy material
Opportunistic Pathogen (rev. meaning)
Provide ex: 7
- Providencia
- Morganella
- Enterobacter
- Srratia
- Proteus
-
Klebsiella Pneumoniae (also Primary Pathogen)
* 7. Escherichia coli (also Primary Pathogen)*
* Organism that can only cause disease under certain condidtions or in certain hosts*
Primary Pathogen: Review
Example: 5
- Shigella
- Salmonella
- Yersinia
-
Klebsiella (also opportunistic)
* 5. Escherichia Coli (also opportunistic)*
Organism capable of causing disease in anyone
Characteristics shared by all Enterobacteriaceae
name all: 5
Gram Neg. rods
Oxidase negative
all can ferment Glucose
Facultative anaerobes
reduce nitrate to nitirite
Tests to Speciate
Lactose Fermentation
H2S production
Reactions such as: Indole/urease/motility
API Tests (Analytical Profile index) to identify diff. bacteria
Antigenic Structure
Ex: 3 major classesof antigens are found
used to differentiate organisms withing a genus or species
- Somatic O Antigens: heat stable polysaccharide par of the LPS.
- Glagellar H Antigens: heat labile
- Envelope or capsule K antigens: overlay the surface O antigen and may block agglutination by O specific antisera. (boiling for 15 min will destroy the K antigen and unmask O antigens)
The K antigen is called the Vi (virulece) antigen in salmonella
Virulence Factors
Endotoxin:
the activity of this toxin depends of the Lipid A
Lipid A
Lipid A is a lipid component of an endotoxin held responsible for toxicity of Gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS, also called endotoxin) molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane;
toxic effects can be damaging, the sensing of lipid A by the human immune system may also be critical for the onset of immune responses to Gram-negative infection, and for the subsequent successful fight against the infection
Escherichia Coli
- Normal inhabitant of GI tract (Produces vitamin K in the L intestines)
- some strains couse various forms of Gastroenteritis
* 3. Major cause of UTI’s (acute cyctitis) - Neonetal Meningitis- Septicemia -*
* 4. Pyelonephritis (kidney infection)*
* 5. some strains aquired additonal “ genetic” info from lasmids, transposons and pages which allow them to be Pathogenic*
E. Coli Antigenic structure
K 1 Has strong association with Virulence
(meningites in neonates)
E. Coli Virulence factors
Toxins: Enterotoxins
produced by enterotoxigenic stains of E. coli (ETEC)
Cause a movement of water and ions form the tissues to the bowel resulting in watry diarrhea;
2 types of Enterotoxins: LT and ST
Pili vs Fimbriae
cell surface appendages present in bacteria other than flagella. These structures are not for locomotion. Pili and fimbriae are surface appendages for attachmen
virulence factors that protect Bacteria from host defenses:
Capsule protects from phagocytosis
Iron capturing ability (enterochelin)
