Microbiolab Supplemental Flashcards
⚫Also an indicator of spoilage
microbial counts
how many ul of inoculum is placed in a hemocytometer
10 ul
how many ul of inoculum is placed in pour plating
1 ml
how many ul is placed in spread plating
0.1 ml
direct count formula
(5)(10)(1000)(DF)
cfu/ml formula
number of colonies * DF/volume plated
⚫Anaerobic to Facultative bacteria will grow.
what kind of bacteria lcount
pour plating
⚫Usually lower count than Spread Plating because of the
hot medium poured into the bacterial suspension
pour plating
can be used to measure
aerobic to facultative anaerobes
spread plating
measures anaerobic to facultative anaerobe
pour plating
⚫It is possible that ___ plating method will give a lower
count because the melted medium can kill the cells.
pour
cell wall synthesis
cycloserine
vancomycin
bacitracin
penicillin
cephalosporins
monobactams
carbapenems
dna gyrase
nalidixic acid
ciproflaxin
novobiocin
quinolones include
nalidixic acid
ciproflaxin
rna elongation
actinomycin
cycloserine
vancomycin
bacitracin
penicillin
cephalosporins
monobactams
carbapenems
what do they inhibit
cell wall synthesis
nalidixic acid
ciproflaxin
novobiocin
what do they inhibit
dna gyrase
actinomycin
what do they inhibit
RNA elongaton
inhibit dna-directed rna polymerase
rifampin
streptovaricins
rifampin
streptovaricins
what do they inhibit
DNA-directed rna polymerase
50s inhibitors
erythromycin
chloramphenicol
clindamycin
lincomycin
erythromycin
chloramphenicol
clindamycin
lincomycin
what do they inhibit
50s inhibitors (protein synthesis)
30s inhibitors
Tetracyclines
Spectinomycin
Streptomycin
Gentamicin
Amikacin
Kanamycin
Nitrofurans
Tetracyclines
Spectinomycin
Streptomycin
Gentamicin
Amikacin
Kanamycin
Nitrofurans
what do they inhibit
30s inhibitors
inhibits tRNA in protein synthesis
Mupirocin
Puromycin
Mupirocin
Puromycin
inhibits what
protein synthesis tRNA
inhibits cytoplasmic memtrane structure
polymyxin
daptomycin
polymyxin
daptomycin
inhibits
cytoplasmic membrane structure
inhibit folic acid metabolism
trimetroprim
sulfonamides
trimetroprim
sulfonamides
inhibits
folic acid metabolism
Causes bacterial cell lysis
and death;
penicillin
:Stops bacterial
protein synthesis, leading to inhibited growth
tetracyclines
Causes DNA fragmentation and bacterial cell death;
quinolones
Prevents protein elongation, stopping bacterial
growth
macrolides
:Results in defective proteins and bacterial cell
death.
aminoglycosides
:Prevents bacterial DNA, RNA, and protein synthesis;
sulfonamides
:Prevents cell wall cross-linking, causing bacterial cell lysis
glycopeptides
example of penicillin
penicillin
amoxicillin
example of tetracyclines
tetracycline
doxycycline
example of quinolones
ciprofloxacin
levofloxacin
examples of macrolides
erythromycin
azithromycin
example of aminoglycosides
gentamicin
streptomycin
example of sulfonamides
sulfamethoxazole
example of glycopeptides
vancomycin
is determined by comparing the zone of inhibition with MIC values in a standard
table
minimum inhibitory concentration
MIC that is sensitive
<= 1
MIC that is intermediate
2-4
MIC that is resistant
> =8
The lowest concentration of an antibiotic that inhibits visible growth of a
microorganism.
minimum inhibitory concentration
allows
the chemotherapeutic agent
to diffuse freely.
Mueller Hinton Agar
Provide the necessary nutrients for bacterial
growth;
what component of MHA
beef extract
Absorbs any toxic metabolites produced by bacteria, helping to maintain
the integrity of the antibiotic;
what component of MHA
starch
Solidifying agent
what component of MHA
agar
: Allows for easy observation of the zones of inhibition around
antibiotic disks
what property of MHA
clear and colorless
Supports the growth of a wide range of bacteria
without favoring any particular type.
what property of MHA
non-selective, non-differential
During incubation, the chemotherapeutic agent __from the disk, from an area of high
concentration to an area of lower concentration
diffuses
: The antibiotic may be somewhat
effective in inhibiting the growth of the bacteria, but not
as strongly as for strains classified as “sensitive.”
what kind of effectiveness
moderate sensitive
means that the bacterial strain being
tested shows a moderate level of sensitivity to the
antibiotic.
intermediate
“mid (temp) loving”; mostly
pathogens; causes most
food spoilage; 20
– 400C
mesophiles
have midrange temperature
optima (optimum
environmental conditions)
mesophiles
found in warm
-blooded
animals; in terrestrial;
and aquatic environments
in temperate and tropical
latitudes
mesophiles
example of mesophiles
e.coli
b.subtilis
“cold loving”; can
grow at 00C
psychrophiles
0 – 20oC
psychrophiles
subgroups of psychrophiles
true psychrophiles
psychrotrophs
psychrotolerant
psychrobacter is __
psychrotroph
athrobacter is a ___
psychrotolerant
heat loving”; 45 – 90C
thermophiles
(extreme thermophiles);
hyperthermophiles
have
evolved to grow optimally
under very hot or very
cold conditions
extremophiles
example of thermophiles
thermotoga maritima
geobacilus stearothermophilus
optimum is 150C; max is
below 200C
pscyhrophiles
optimum 200C to 400C
psychrotolerant
optima range is 0oC to
35oC
psychrotrophs
Thermococcus celer;
Methanopyrus kandleri;
Pyrolobus fumarii (1060C)
what kind
hyperhermophiles
cells are composed of what percent o fwater
80-90
Lactobacilli
what kind of pH
acidophiles
Bacillus,
Micrococcus,
Pseudomonas,
and
Streptomyces
what kind of pH
alkaliphiles
: thrives in the presence of carbon dioxide
capnophiles
example of strict aerobes
m. luteus
alcaligenes faecalis
example of facultative anaerobes
e.coli
e. faecalis
example of aerotolerant anerobes
l. bulgaricus
example of microaerophile
campylobacter haemophilus
example of obligate anaerboes
c. sporogenes
A liquid medium designed
to promote growth of a
wide variety of fastidious
microorganisms.
fluid thioglycollate medium
compounds that act as surfactants
that alter membrane permeability of
some bacteria and fungi (Not
sporicidal)
quaternary ammonia
most resistant to least resistant
prions
endospores of bacteria
mycobacteria
cyst of protozoa
vegetative protozoa
gram-negative bacteria
fungi (incl. most fungal spore forms)
viruses without envelopes
gram-positive bacteria
viruses with lipid envelopes
water quality parameters is divided into 3
physical
chemical
microbial
water intended
for direct human consumption or
use in food preparation
drinking water
– water suitable
(both health and acceptability
considerations) for drinking and
cooking purposes .
potable water
other water aside from drinking and potable
recreational
marine
coastal
family of e coli
enterobacteriaceae
lactose fermenters of enterobacteriaceae
e. coli
citrobacter
kliebsella
enterobacter
non-lactose fermenters of enterobacteriaceae
salmonelli
shigella
proteus
yersinia
By gram staining or
Using selective medium for g-neg i.e
EMB, Endo agar, MacConkey
what does it detect
rod-shaped, non-spore forming gram negative bacteria
Gas production caught in the Durham
tubes; dark colonies pink, red, purple
with green metallic sheen.
what does it detect
lactose fermenter at 37
___ pH cause yellow coloration in
Lactose broth; metallic sheen and
purple surrounding with low pH on
plates
acidic
Dark coloration of colonies attribute dto
acetaldehyde
total coliforms should be at a conformity lvel of __
<1 cfu/100 ml
e coli test must give a result of
<1.1 mpn/100ml
<50MPN/100 mL means
conformity, low, and intermediate risk level
v<50MPN/100 mL what treatment needed
disinfection alone
> 50MPN/100mL and <5,000 MPN/1000 mL
high and very high risk leve>50MPN/100mL and <5,000 MPN/1000 mLls
> 50MPN/100mL and <5,000 MPN/1000 mL
what treatment
complete treatment
selective, differential agar
medium used for isolation of
gram-negative rods in a variety
of specimen types
EMBA
inhibits the gram
+ bacteria in EMBA
methylene blue
changes
color to a dark purple, when the
medium around the colony
becomes very acidic
what component of EMBA
eosin
key nutrient;
fermented by coliforms to
produce acid
lactose
Gram neg,
Darkened purple with strong acids produced from lactose
Metallic green with low pH – rapid fermenter
Fecal coliform
what is present in EMBA
green metallic sheen: e.coli
Gram neg,
Darkened with strong acids produced from lactose
No Metallic green, pH did not lower – slow fermented
Coliform, but non-fecal
what is present
dark pink/red
enterobacter aerogenes
Gram neg,
Did not darken - no acids produced from lactose
No Metallic green, pH did not lower – non-fermenter
Non-coliform
what is present in EMBA
light pink/colorless
P.aeruginosa
is a technique that uses a physical
barrier (usually a porous membrane
or filter) to separate particles and
microorganisms suspended in a fluid
sample including food, air and
water.
membrane filtration technique
filter membranes retain
particles or microorganisms larger
than their pore size primarily by
surface capture
what kind of filter membranes
cellulose nitrate
cellulose acetate
major advantage of the membrane filtration
technique over the MPN technique is that it
isolates discrete colonies of bacteria
what agar is used for membrane filtration technique
Endo agar or EMB
provide results
on bacterial count within
24 hours unlike the MPN
technique that takes
several days to conclude.
membrane filtration technique
goals of testing are to detect possible drug
resistance in common pathogens and to assure
susceptibility to drugs of choice for particular
infections
antimicrobial assay
method used for antimicrobial assay
broth microdilution
disk diffusion
gradient diffusion
MIC or zone diameter
value used to categorize an organism
as susceptible, susceptible-dose
dependent, intermediate, nonsusceptible, or resistant.
breakpoint
category
derived from microbiology
characteristics,
pharmacokinetic/pharmacodynamics
parameters, and clinical outcome
data, when available
interpretive category
–breakpoint that implies that isolates with an MIC at
or below; or zone diameters at or above the susceptible breakpoint
inhibited by the usually achievable concentrations of antimicrobial
agent when the dosage recommended to treat the site of infection
is used, resulting in likely clinical efficacy.
susceptible
breakpoint that implies that
susceptibility of an isolate is dependent on the dosing regimen that
is used in the patient. I
suceptible-dose dependent
–breakpoint that includes isolates with MICs or
zone diameters within the intermediate range
intermediate
breakpoint that implies that isolates with an MIC at or above
or zone diameters at or below the resistant breakpoint
resistant
