Bacteria & viruses Flashcards
Linnaeus system of naming organisms
generic name (genus) specific name (species)
example:
Escherichia coli (can be abbreviated E. coli)
what is the difference between gram-negative and gram-positive bacteria. How does that stain work?
gram-positive:
- thin layer of peptidoglycans in cell walls
- pink conunterstrain
(if stain comes out with alcohol)
gram-negative:
- thick layer of peptidoglycans in cell walls
- remains purple
- stain does not come out
all bacteria stain purple with crystal violet
Aerobic
Can survive and grow with the present of oxygen
Anaerobic
Does not require oxygen for growth (some will die in the presence of
- Obligate anaerobe: Die in the presence of oxygen
Facultative anaerobe
Uses oxygen if available but has the ability to use anaerobic methods by energy production
Microaerophilic
Require oxygen for growth but are harmed by atmospheric concentration of oxygen (21%)
Aerotolerant
Do not require oxygen but not poisoned by it
explain the two main divisions of gram-negative bacilli. Know what biochemical test and what agar we use to differentiate them?
- enterics: bacteria that are facultative anaerobic rods that ferment sugars to produce acid and gas
- non-enterics: primarily opportunist, causing infections in the severe illness of hosts. can be isolated from the environment
MacConkey agar to select and differentiate:
- If cannot ferment sugars, will not grow
- Turns pink if can ferment lactose
- Colorless if cannot ferment lactose
Is E. coli gram-negative or positive? Is it a rod or cocci?
- gram-negative
- rods
a lactose-fermentor
what are the three types of pathogenic strains of E. coli?
1.Enterotoxigenic (ETEC)
2. Enteropathogenic (EPEC)
3. Enterohemorrhagic (EHEC)
Enterotoxigenic (ETEC)
- Heat-labile & heat-stable toxins
- example: Edema disease
Enteropathogenic (EPEC)
- Attaching and effacing mechanism
- example: Neonatal calf diarrhea
Enterohemorrhagic (EHEC)
- E. coli O157:H7 strain, uses bacterial fimbriae for attachment and has a Shiga-like toxin
- example: Hemolytic uremic syndrome
what is endotoxin?
- Came out of Gram-negative bacteria
- All have lipopolysaccharide outer membrane of the cell wall
What is the primary Salmonella species that we deal with in veterinary medicine? Is it gram negative or positive? Is it a rod or cocci?
2 salmonella species:
S. enterica (PRIMARY)
S. bongori
- gram-negative
- rods
what antigen is used to group S. enterica?
Salmonella Typhimurium
S. enterica subsp. enterica serovar Typhimurium
Group B, 1,4,5,12:i:-
Is Yersinia pestis gram negative or positive? Is it a rod or cocci? What is the common name of the disease that it causes?
- gram-negative
- rods
- common name, “plague” (bubonic plague)
what are the three forms of Yersinia pestis disease that are seen in animals?
Bubonic form:
- Acute disease with lymph node abscessation
septicemic form:
- Necrosis of liver, spleen and lungs
Pulmonic form:
- Severe acute pneumonia
Affects the liver, spleen, and lungs
Is Pseudomonas aeruginosa a primary pathogen? Or is it opportunistic? Is it gram-negative or positive? Is it a rod or cocci?
- opportunistic pathogen
- gram-negative
- rod
Is Brucella gram negative or positive? Is it a rod or cocci?
- small gram-negative
- cocci
Is Francisella tularensis gram negative or positive? Is it a rod or cocci? What is the common name of the disease that it causes?
- gram-negative
- rod
- Tularemia
what are 3 forms of Francisella tularensis that are seen in animals?
- Pneumonic form
- typhoidal
- ulceroglandular or oculoglandular
what does Haemophlius require in order to grow on blood agar?
- Require hemin, NAD, or NADP in order to grow on blood agar (satellitosis)
- tiny gram-negative pleomorphic rods
one of the few gram-negative diseases that can be treated with PENICILLIN
what are the three general groups of gram-positive bacilli?
Endospore formers: Bacillus, Clostridium
Non-endospore formers: Listeria, Erisipelothrix
Irregular-shaped and staining properties: Corynebacterium, Mycobacterium, Actinomyces, Nocardia
