2. General Bacteriology 2 (Tesse) Flashcards
what are the stages of a bacterial growth curve
lag phase
exponential growth phase
stationary phase
decline
What are the two common DIRECT approaches to bacterial growth assessment
Microscopic counts (total cell counts)
culture counts (viable colony counts)
What is the main INDIRECT approach to bacterial growth assessment
measure cell mass (optical density measured via specttrometry)
What is a generation time>
the time it takes for bacterial population to double
What are some examples of sources of microorganisms?
other animals, environment, normal commensals, body fluids, direct contact, feed, water, fomites
what are the seven chronological steps of microbial disease
- acquire portal of entry
- encounter targets
- colonize/cross barriers
- spread locally and colonise new population of targets
- enter blood or lymph
- spread
- dysfunction or disease
What are four examples of host defenses?
Physical barriers
chemical barriers
transport systems
immune system
give 5 ways to reach bacterial diagnosis
- visualization of bacteria
- isolation
- bacterial genetic material
- rise of antibody titre
- specific cellular immune response
How is direct examination of bacteria done?
staining
what are the three main culture materials
Blood, macconkey, chocolate
What is MALDI?
mass spectrometry for bacterial identificatiom
How can you diagnose bacterial infection using serology
paired serum samples two weeks apart showing a 4x increase in antibody titre
What is the tuberculin test?
skin test that detects cellular immune response
what is sterilization
destruction of all viable microorganisms
what is disinfection
reduction of pathogens on inanimate objects to levels below infectious
what is antisepsis
inactivation or destruction by chemical means
is boiling considered a method of sterilization
no, the spores can be resistant
what are three physical methods of sterilization
heat, filtration, irradiation
when is chemical sterilization used
used to sterilize equipment that cannot tolerate heat
t/f: disinfection is useless if you dont remove organic matter beforehand
true
what are some disinfective agents
virkon, prevail, alcohol, preempt, bleach
t/f alcohol is a great disinfector for skin, because it kills all pathogens and prevents more from colonizing the skin for up to 5 hours.
false! alcohol is good for initial disinfection, but allows for high bacterial growth on that surface afterwards
what are two types of antiseptics used in vet med
iodine (not used often)
chlorhexidine
when would you choose to use iodine over chlorhexidine to prep a patient
if your procedure is near the eyes or ears (it can cause blindness and deafness)
What is binary fission
bacterial replication that results in two identical daughter cells
What is the duration of each phase of the bacterial growth cycle dependent on
the organism itself, and the growth conditions
What is commensalism
a relationship between two organisms in which one benefits and the other is neither benefited or harmed
What are the main portals of entry for bacteria
mouth, skin, respiratory tract, GIT, urogenital tract, eyes, ears, placenta, umbilicus, mammary glands
what are the main methods of infection
ingestion, inhalation, ascending infection, direct penetration
what is an example of a physical host barrier
skin, mucous in GI
what is an example of a chemical host barrier
acid in stomach
what is an example of a host transport system
mucociliary system
what is an example of an immune-related host defense
mucosal associated lymphoid tissue (MALT)
What stain should you use for bacteria that dont pick up gram stain very well
acid fast or modified acid fast
what is KOH good for
staining keratinized structures
What should the clinical significance of a culture result be considered in the light of
the cytological findings of the affected site (ie rule out contamination)
What does blood agar detect
presence of hemolysins
what does macconkey agar detect
gram negatives and ability to ferment lactose
What is chocolate (hematin) agar used to detect
Haemophilus sp,
how can you detect bacterial genetic material
PCR
What is pasteurization
heating food to a degree that kills all potential human pathogens
