Flashcards in Bacteria (Part I) Deck (117)
what are the three methods of transfer of plasmids?
direct conjugation, infective viral transduction, or transformation
Why are plasmids significant?
they confer various factors and traits to bacteria allowing them additional virulence factors or antibiotic resistance
What are the 4 steps following heat fixing material to slide?
1) Crystal violet (primary dye) 2) Iodine (dye trapping agent) 3) Alcohol (decolorizer) 4) Safranin (counterstain)
Why are gram positive bacteria purple?
they have a relatively thick cross-linked cell wall made up of peptidoglycan which helps to retain the crystal violet stain
What is the composition of gram negative cell walls?
they have thinner cell walls with a high lipid content which is primarily washed away by the alcohol
What gives gram negative bacteria their pink stain?
the safranin (the counterstain)
the gram positive bacteria have a thick peptidoglycan wall with embedded what? (2)
techoic and lipoteichoic acids
What is used in serologic bacterial identification? (2)
techoic and lipoteichoic acids
What do the lipopolysaccharides on the gram negative bacteria cell wall contain?
lipid A- which can act as an endotoxin
What are 2 gram stain exceptions?
gram variable bacteria and acid fast bacilli
what are 2 examples of gram variable bacteria?
clostridium and bacillus species
What is an example of an acid fast bacilli?
What do acid fast bacilli contain and why is this important?
they contain mycolic acids, which make it difficult for the gram stain to penetrate the waxy cell wall
How is the acid fast stain different from the gram stain?
the acid fast stain has a different primary stain and counter stain the the typical gram stain. It also utilizes an acid decolorizer step
how are cocci bacteria characterized?
how can cocci be arranged? (3)
in pairs called diplococci, chains called streptococci, or clusters called staphylococci
Some bacilli have unique features such as what?
the presence of spores or the presence of club shaped ends
when a bacteria has an ovoid shape in between a rod and a sphere what is it referred to as?
what are the helical shaped bacteria called?
what are the curvilinear bacteria referred to as?
Besides gram stains, what else can be used to see spirochetes and spirilla bacteria?
what are the comma shaped bacteria?
What are the pros and cons of molecular techniques for microbiology?
pros: sensitive and specific cons: expensive
what is serology utilized for?
organisms that don't culture well (fastidious organisms) and for which there is not a good nucleic acid test developed
what is an example of an organism that uses serologic tests for diagnosis?
syphilis- from Treponema pallidum
What are the 6 major types of gram positive disease causing bacteria?
1) Staphylococcus 2) Streptococcus/Enterococcus 3) Bacillus 4) Clostridium 5) Corynebacterium 6) Listeria
the major gram positive disease causing bacteria consist of two main groups. What are these groups?
Cocci and Bacilli
How can the gram positive cocci be further broken down?
based on whether the organisms are catalase + or Catalase -
How can the gram positive bacilli be further broken down?
based on whether the organism is spore forming or non spore forming