question
what are the ingredients in litmus milk
answer
litmus milk (indicator) skim milk powder
question
how does the litmus milk test work?
answer
determines the fermentation of lactose and/or proteolysis and serves as both a pH indicator and O/R indicator
question
What are the four primary reactions or results that we can observe in the litmus milk test?
answer
change in pH, change in oxidation reduction, curdling of milk and proteolysis
question
change in pH litmus milk test result is due to
answer
excretion of acid or alkaline fermentation products
Result: red for acid production, blue for alkaline production
Result: red for acid production, blue for alkaline production
question
change in oxidation reduction in litmus milk test
answer
potential from oxygen depletion
as the oxygen becomes depleted
as the oxygen becomes depleted
question
What organism did we use to test transmission and why did we use this organism?
answer
serratia marcescens
-can cause opportunistic infection
-can cause opportunistic infection
question
How did we test for transmission (i.e. what were our two experiments)? Was there an effect of handwashing in our experiment?
answer
touching door knob, shaking hands, washing
direct infection, shaking hands, washing
handwashing alone was still decently effective
direct infection, shaking hands, washing
handwashing alone was still decently effective
question
what is coagulation?
answer
blood clotting
question
what causes coagulation
answer
production of coagulation enzyme by bacteria
question
what does coagulation do
answer
causes a clot to form around bacteria and protects it from being attacked by the hosts and phagocytes
question
What test is done to detect coaguation? How does the test work?
answer
blue beads test
question
How does curdling happen?
answer
acid secreted during acid fermentation causes casein to lose its structure (denaturation) (large unfolded proteins)
question
hydrolysis of casein due to extracellular degradation enzymes
answer
proteolysis
-will produce clear fluid or brownish/amber color
-will produce clear fluid or brownish/amber color
question
nonliving objects capable of transferring bacteria
answer
fomites
question
frequent causes of nosocomial infections acquired in a medial facility
answer
endogenous and exogenous
question
infections caused by members of patients own natural microflora
-appendix, antibiotic, weakened immune system
-appendix, antibiotic, weakened immune system
answer
endogenous
question
invade from patients surrounding environment: ie other patients, staff, objects
answer
exogeneous
question
What is hemolysis? What are the types of hemolysis we discussed in class?
answer
hemolysis is the breakdown of RBC. Types: beta, alpha, gammma, sometimes delta (effect different cell types)
question
What is blood agar and how does it work to detect hemolysis? Be able to identify hemolysis on a blood agar plate.
answer
discriminants microorganisms that effect RBC in one or more ways
question
brings about complete destruction of RBC
answer
Beta hemolysis
question
makes a clear colorless in the agar
answer
beta hemolysis
question
involves partial lysis of RBC
answer
alpha hemolyisis
question
makes a greenish brown zone due to reduction of hemoglobin
answer
alpha hemolysis
question
used to describe situation in which there is no change in agar around colony
answer
Gamma hemolysis
question
Where are you most likely to find skin organisms?
answer
on forearm
question
What are some characteristics that you might expect from species that live on skin?
answer
...
question
resident vs transient bacteria
answer
Resident: born with it,
Transient: comes and goes, bacteria that would be collected from water fountains, etc.
Transient: comes and goes, bacteria that would be collected from water fountains, etc.
question
the differing types of defenses our bodies have
answer
mechanical, chemical, microbial
question
mechanical defense ex
answer
hair, cilia, skin
question
chemical defense
answer
stomach acid, sweat
question
microbial defense
answer
antibiotics
question
•Understand activities or factors that can reduce the effectiveness of these defenses
answer
being wet essentially can cause bacteria growth, using some drugs to combat other problems, traumatic injuries or punctures
question
Where do resident microbiota reside
answer
moisture or chemicals that we excrete daily
question
Some people may carry a virulent pathogen that does not affect them but may infect others. These people are called
answer
carriers
question
Candle jar uses a flame to
answer
•to use up available oxygen
Increased CO2 presence
Minimal, but not absent oxygen - microaerophilic
Increased CO2 presence
Minimal, but not absent oxygen - microaerophilic
question
What type of bacteria typically reside in the throat?
answer
non-pathogenic or are opportunistic pathogens
question
mechanical defense inURT
answer
sneezing
question
chemical defense in URT
answer
production of interferon
question
microbial defense in throat
answer
resident organisms outcompete transient organisms fro nutrients
question
o Is urine sterile?
answer
no
question
More commonly used for UTI diagnosis and designed to give an appropriate snapshot into the microbiome of an individual.
answer
mid stream catch
question
o What types of tests could be performed to determine if bacteria in a urine sample are pathogenic and why can these tests help determine pathogenicity?
answer
mid stream and first stream catch
CFU/mL calc
CFU/mL calc
question
o How might you determine if a person has a urinary tract infection?
answer
more than 100,000 cf/mL
question
How do you differentiate between a harmful and a normal bacteria?
answer
•Hemolysis, EMB growth, etc.
question
oligosaccharides have
answer
few sugars
question
ex of structural polysaccharide
answer
cellulose
question
ex of nutrient poly
answer
glycogen and starch
question
two forms of starch
answer
amylose and amylopectin
question
amylose is a __ chain and amylopectin is
answer
straight, branched
question
enzyme that hydrolyzes starch is
answer
amylase
question
_____ Breaks down amylose and amylopectin to form ____
answer
amylase, maltose
question
zone of hydrolysis
answer
clear area that will be evident around an amylase-producing colony after the plate is flooded with iodine
due to the breakdown of starch into maltose
due to the breakdown of starch into maltose
question
starch hydrolysis test postive rxn
answer
clear zone around colony
question
starch hydrolysis neg rxn
answer
entire plate is red or blue w no clear zones
question
•When casein binds to calcium, it forms
answer
•calcium caseinate which is water insoluble
question
•Casein being water insoluble - colloid - makes it a good
answer
indicator for rxn
question
•To study the degradation of casein we are using a
answer
milk plate
question
•If the bacteria is able to digest casein
answer
•a clearing will appear around the growth as the digested amino acids from casein are now soluble
question
•To study the degradation of gelatin we are using
answer
gelatin deeps
question
•If the bacteria is able to digest gelatin, the deep
answer
will not be solid at RT
question
Enzymes which hydrolyze glycerol by separating the ester linkages between glycerol and the fatty acid molecules
answer
lipases
question
Food spoilage in which unpleasant odors and flavors develop due to the release of free fatty acids from triglycerides
answer
rancidity
question
Phospholipases degrade phospholipidse.g.
answer
hemolysis
question
•To study lipases we are using
answer
spirit blue agar
question
spirit blue agar shows
answer
•the release of fatty acids as the medium contains a pH indicator and the fatty acid release will change the pH
question
•To study phospholipases we are using
answer
egg yolk agar
question
•This agar will become opalescent when the fatty acids are broken down due to the accumulation of water insoluble fatty acids
answer
egg yolk agar
question
Enterobacter aerogenes is very similar to E. coli and survives in a variety of environments - soil, plant surface - it's presence does not guarantee fecal contamination!
answer
complications
question
Lauryl-tryptose broth contains
answer
sodium lauryl sulfate (SLS) which is a detergent similar to that found in bile fluid that enteric bacteria can tolerate in the small intestine
question
Presumptive Test
answer
•A water sample is inoculated into lauryl-tryptose broth, •A Durham tube is placed in broth
question
If gas in the tube is positive
answer
the bacteria is now 'presumed' to contain fecal coliforms and the water sample is considered unsafe
question
confirmed test (skipped)
answer
•Lauryl-tryptose broth is used to inoculate brilliant green lactose bile (BGLB) broth
•A Durham tube is placed in broth
If gas in the tube is positive
the bacteria is now 'confirmed' to contain fecal coliforms and the water sample is considered unsafe
•A Durham tube is placed in broth
If gas in the tube is positive
the bacteria is now 'confirmed' to contain fecal coliforms and the water sample is considered unsafe
question
distinguishes bacteria that ferment lactose with the production of much acid from those produce little to no acid
green metallic sheen from E. coli is caused by excretion of copious amounts of acid causing precipitation of the dye in the agar
green metallic sheen from E. coli is caused by excretion of copious amounts of acid causing precipitation of the dye in the agar
answer
complete test
question
Fecal coliforms such as E. coli produce dark colonies with a
answer
•green metallic sheen
question
Noncoliforms such as Enterobacter aerogenes produce
answer
light pink or colorless colonies with fisheye colony morphology
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