Week 8 notes Flashcards
What specific requirements do bacteria have?
temp, pH, oxygen tension, and nutrition
what are the oxygen requirements of the following bacteria: obligate aerobes, obligate anaerobes, facultative anaerobes, microaerophilic, capnophilic?
obligate aerobes- need O2 to survive
obligate anaerobes- need no o2 to survive
facultative anaerobes- can survive in O2 but don’t need it
Microaerophilic- need reduced levels of O2
Capnophilic- need CO2 to survive
Most bacteria grow at what pH?
Between 6.5 and 7.5
What temperature do each of these mean: mesophilies, psychrophilies, thermophilies?
mesophilies- 20-40’ C
psychrophilies- lower than 20’C
thermophilies- higher than 40’C
What are the cell shapes?
Bacilli, cocci, spirals
What are the different cell arrangements?
chains, clusters, pairs, tetrads, palisades
Endospores are resistant to?
heat, desiccation, chemicals, and radiation
What are the 4 phases of bacterial growth?
- initial (lag), 2. Exponential (doubling or rapid), 3. Stationary, 4. Final (death)
what does saprophytic mean?
decomposers
what is mycelium and hyphae of yeast?
hyphae- webs of slender tubes, mycelium- a branching web made of hyphae
What are basidiomycetes, ascomycetes, zygomycetes, and deuteromycetes?
basidiomycetes- mushrooms or club fungi
ascomycetes- cup fungi
zygomycetes- molds
deuteromycetes- have no identifiable sex stage
What do you need for an in-house micro lab?
lighting and ventilation, washable floor, limited traffic, two work areas, smooth non porous surfaces, electrical outlets, storage, access to incubator and refrigerator
What are the safety practices you should do if working in a micro lab?>
know the potential for pathogenic or zoonotic diseases, aseptic technique, PPE, wash hands, disposal, treat spills immediately, no eating, drinking, or cosmetics, hair pulled back, report accidents immediately
what are the two types that media is made of?
agar- from algae and gelatin- from animal cells
What are the 6 types of media and what do they do?
Transport- designed to keep alive but not grow
enriched- meets requirements for facigest bacteria
selective- contains anti-bacterial so only certain type grows
differential- allows bacteria to group
enrichment- helps a certain type to grow
What are the four types of hemolysis that can be detected on blood agar? What do they look like?
Alpha- narrow band of greenish slime (partial)
Beta- creates clear zone (total)
Gamma- no change noticeable
Delta- Both alpha and beta
Macconkey Agar suppresses the growth of ? what do lactose colonies look like?
gram positive bacteria; pinkish red colonies
Thioglycollate broth is used to culture what?
anaerobic bacteria
What is a positive reaction in a urea tube?
pink color change
What is a positive reaction in a Simmons citrate tube?
Blue color change
What is mannitol salt agar used for?
Selective for Staphylococci
Bismuth sulfite agar suppresses ______ and allows ______ to grow
Coliform; salmonella
What are three types of dermatophyte test media?
DTM, RMS, EMS
Name three sample collection methods
Aspiration, swabbing, imprints
What specimens should you use sterile aseptic technique?
Urine, pustules, ears and fecal
What do you need to label a micro sample with?
History, owners name, clinic name, address and phone number, signalment of all animals affected, duration, major signs, DDx, organism suspected, treatment, investigation required
What is the most common stain (micro)?
Gram stain or Ziehl-Neelsen stain
What are some simple stains?
Crystal violet and methylene blue, lactophenol blue
What are the four steps of staining (micro)?
Primary stain, mordant, decolorizer, counter stain
Gram positive bacteria stain?
Purple
Gram negative stain?
Red
KOH verifies what?
Gram status
Gram negative developer what with a KOH test?
Mucoid appearance and sticky strands
What some colony characteristics?
Size, pigment, density, elevation, form, texture, odor, hemolysis
The agar diffusion method uses what?
Paper disks impregnated with antimicrobials
Indirect sensitivity testing requires what?
A colony cultured then subcultured in a broth media, incubated until specific turbidity achieved, and that singel-colony sample is used
Direct sensitivity testing requires?
Sample is used directly
What are the different interpretations of zone sizes?
Resistant, susceptible, intermediate susceptibility
Why is motility media used?
Is organisms are nonmotile on micro exam
Catalase tests are performed on?
Gram positive cocci and small gram positive bacilli
Coagulase test is performed on?
Catalase positive and gram positive cocci
What is a positive reaction on oxidase activity test?
Purple color change within 60 seconds
How do you grade a CMT?
Negitive, trace or 1,2,3, gelling
What supplies do you need for mycology?
Forceps, swabs, lactophenol cotton blue stain, potassium hydroxide solution, culture media, woods lamp, cellophane tape, and separate room and incubator
DTM turns what color in the presence of dermatophytes?
Red
The most appropriate specimens for bacterial culture are collected from?
From sites that are normally free of bacteria
Acid fast stain is used to identify?
Mycobacterium and nocardia
Organisms that exhibit a gram variable reaction should be evaluated by what test?
KOH
To collect samples at optimal times it would be best to sample them?
Early in the course of the disease
__________ is the best way to collect bacterial culture from urine.
Cystocentesis
MacConkey agar is selective for bacteria that can grow in the presence of bile salts which is similar to the environment found in?
The intestines
Inoculated media plates are incubated in an inverted position to?
Prevent condensation of water on the lid
A positive result for the _____ test results in bubbles of oxygen produced on a slide when bacteria are introduced into a drop of hydrogen peroxide.
Catalase
The most important member of the Bacillis family is?
Bacillus anthracis
Describe the quadrant streak method
First streak on quad of plate (thickest) then make three more streaks ending in the middle of the plate.
What is the purpose of the quadrant streak method?
To be able to obtain a single colony
