Lab Exam 2 Microbio
After culture of bacteria, the red color of urea broth that contains phenol red indicates that urease produced by the bacteria converted urea into ____. What is the name of molecule in the blank?
Ammonia
Catalase
An enzyme produced in all cells to decompose hydrogen peroxide, a by-product of cell respiration
true or false Fermenting lowers the pH of the MSA medium turning color into pink.
False Fermenting lowers the pH of the medium turning color into yellow.
True or False Staphylococcus aureus can ferment mannitol, but Staphylococcus epidermidis can't.
True Staphylococcus aureus can ferment mannitol, but Staphylococcus epidermidis can't.
True or false Gram-positive bacteria will not form any colonies on MacConkey medium.
True Gram-positive bacteria will not form any colonies on MacConkey medium. Crystal violet and bile salt inhibit the growth of gram-positive bacteria.
True or false? Lactose-fermenting microorganisms lower the pH of McConkey Agar
True Lactose-fermenting microorganisms produce organic acids, particularly lactic acid, which lowers the pH (colorless at neutral, bright red/pink below 6.8)
True or False most of the time Staph Aureus is harmless but can be one of the serious causes of infection .
True Staphyloccocus aureus is harmless to most healthy individuals but can opportunist bacterias.
Urinalysis (Urine test
Turbidity by looking White blood cells by microscope Leukocyte esterase detection by a rapid dipstick test (leukocyte esterase is released when leukocytes die.) pH test Detecting other proteins and nitrate
Increase elimination of the medication
Using efflux pump, bacteria can remove antibiotics from their cytoplasm.
identification of pathogens
Using selective and differential media such as MacConkey Agar. • Beta-hemolysis test
MacConkey Agar (MAC)
Gram negative bacteria like it. Gram + don't like to grow on it.
Pdase test (phenylalanine deaminase test)
Gram negative test green: + yellow:- testing for the enzyme: phenylalanine deaminase (pheynylalanine deaminase deaminates the amino acid phenylalanine)
lactose negative bacteria( gram negative bateria)
Gram-negative bacterial species will still form colonies, but colonies will have a white appearance as there will be no change in pH in the absence of lactose fermentation.
significant bacteriuria."
Greater than 100,000 bacterial colonies per milliliter urine sample
_________________uses urease to produce ammonia and neutralize gastric acid in human stomach.
Helicobacter pylori
MRSA
Hospital-acquired MRSA (HA-MRSA) Community-acquired MRSA (CA-MRSA)
What does bubbling result indicate in catalase test ?
Indicates the presence of catalase
___________________binds to starch and form blue-purple colored complex.
Iodine
Selective and differential Medias
Manitol Salt Agar(MSA)) MCconkey Agar (MAC)
Fc receptor that binds to antibodies, preventing them from functioning. It binds to Fc regions of the B-cell receptor, killing them.
Protein A
urea positive bacteria
Proteus vulgaris
__________________________are also problems, especially in hospitalized patients with indwelling urinary catheters or those receiving multiple antimicrobial agents.
Pseudomonas and Acinetobacter
How to collect and store voided urine sample
Refrigerate urine samples. Add boric acid to urine samples. Boric acid inhibits bacterial growth in the sample for up to 12 hours at room temperature. Use "Clean-Catch" or "Clean-Voided" Techniques to collect voided urine samples.
S. Aureus are beta-hemolytic but __________________ and ________________ are not
S. epidermidis S. saprophyticus
_________________________ has resistence to low concentration of novobiocin
S. saprophyticus
meticillin-sensitive Staphylococcus aureus (MSSA).
S.aureus infections that are more susceptible to methicillin .
Lactose negative species
Salmonella, Proteus, Yersinia, Pseudomonas
Types of Staphylococcus
Staphylocccus aureus Staphylococcus epidermidis Staphyloccus saprophyticus
Which bacterial species turn MSA plates yellow ?
Staphyloccoccus aureus Turns MSA plates yellow because it ferments mannitol
High salt concentration blocks growth of bacteria, but members of _______________________ can grow (halotolerant bacteria).
Staphyloccocus
Gram positive bacteria:
Staphylococci, Bacillus subtilis
Major cause of nosocomial infections
Staphylococcus aureus
True or false The end products of DNA digestion are not dissolved and removed by weak acid, but the large DNA molecule does dissolve in weak acid
false The end products of DNA digestion are dissolved and removed by weak acid, but the large DNA molecule does not dissolve in weak acid
how does bacteria avoid host defenses ?
fc region on bacteium bind to fc region of antibodies
DNase
breaks down DNA
urease
breaks down urea
signs and symptoms of cystitis
burning on urination, frequency, urgency, urine discolored (pale or red ) and foul smelling Pain in area above pubic bones
Enterotoxin
can cause food poisoning
some bacteria split urea molecules in two releasing __________ and ________________
carbon dioxide ammonia
Bacterias that produce urease break down urea in the medium(phenol red+ urea medium) causing release of ammonia which increases the ph. How does that change the results
causes a change from orange pink to dark pink
TSST-1
causes toxic shock syndrome (TSS) in the users of highly absorbent tampons
decrease in uptake of medicine
changes in protein prevent reuptake of antibiotics
staphylococcus aureus produces ____ that coagulates plasma
coagulase
defense mechanisms of S.aureus
coagulase production hemolysin production catalase production
beta hemolysin streptococci cause
complete destruction of RBCs in surroundings
Kligler Iron Agar (KIA) Test
contains the carbohydrates glucose and lactose and a pH indicator that changes from red to yellow when acids are produced by fermentation of either of these simple sugars
what is the inflammation in the urinary bladder?
cystitis
tryptophanase
degrades amino acid tryptophan into pyruvic acid, ammonia ,indole
In addition to basic nutrients, ________ media contain one or more components, such as a particular carbohydrate, that can be used by some microorganisms but not by others. If the microorganism uses the component during the incubation period, a change occurs in an indicator that is also included in the medium, which results in a color change in the medium.
diferential
McConkey Agar
differentiate lactose fermenters (pink colonies) and lactose non fermenters (yellow colonies)
Hyaluronidase
digests hyaluronic that hold cells together to help infections penetrate more deeply
Staphylokinase
dissolves fibrin clots
alpha-hemolytic streptococci
does NOT lose the red blood cells, but the hemoglobin in converted to methemoglobin (partial RBC destruction)
ways Staph aureus is transmitted
during the first days of life via transmission from mother to child. after birth the hands have been identified as the main source of transmission from mother to child.
Mechanism of Acquired Resistance
enzymes inactivate antibiotics alteration of target molecules decrease in medicine uptake increase in medication elimination
Staphylococci are _____.
facultative anaerobes
true or false Bacteriuria always indicates UTI
false Bacteriuria does not always indicate UTI. factors such as container of urine , bacteria on skin , normal flora at the end of urethra can affect how sterile urine collection is
true or false Some facultative anaerobes and aerotolerant anaerobes also are catalase positive
false Some facultative anaerobes and aerotolerant anaerobes also are catalase negative
true or false Pseudomona Aeruginosa ferment all carbohydrates
false Pseudomona Aeruginosa doesn't ferment at all.
true or false Staphylococcus saprophyticus is part of normal flora
false Staphylococcus saprophyticus is not a part of normal flora
Seratia marcescens ferments
glucose sucrose
Smaller sugars such as ____________and _____________don't interact with iodine, so no color is formed.
glucose and maltose
E. coli ferments
glucose(yellow result)
Staphylococci are ___, irregular cluster like grapes.
gram-positive cocc
Virulent Factors of Staphylococcus aureus
hemolysin coagulase leukocidin hyaluronidase staphylokinase enterotoxin
staphylococcus aureus produces ___ that destroys red blood cells.
hemolysins
Kovac's reagent reacts with____________producing brilliant red color.
indole
microorganism causing cystitis
opportunistic pathogens of the fecal flora, gram-negative bacteria such as E. coli, Klebsiella, Enterobacter, Serratia, and Proteus.
acute urethral syndrome.
patients with symptoms of cystitis have low counts of the causative agent in their urine.
Deaminase of phenylalanine forms ________________ that reacts to ferric ions forming green color.
phenylpyruvic acid
hemolysins
pore-forming toxins that damage destroy red blood cells through hemolysis
Quadrant four indicates
presence of a non lactose fermenter (salmonella typhimurium )-4
pros of catheterized urine specimens
prevents contamination of sample from normal urogenital flora. So, it presents condition of urine properly.
nonfermenter
pseudomonas aeruginosa
what is the type of UTI that generally begins in your urethra or bladder and travels to and multiply in one or both of your kidney?
pyelonephritis
Which quadrants contain lactose fermenters
quadrant 1 (Enterobacto Aerogenes)and quadrant 2(E. COli) grew red/pinkish colonies
spontaneous mutations
random change in the DNA due to errors in replication that occur without a known cause Combination therapy of multiple antibiotics used;unlikely cells will simultaneously develop resistance
The presence of indole following is indicated
red pink color ( specifically Staph aureus
Which of the following has the risk of infection in urinary bladder and cystitis?
sampling catherized urine specimens
Gram negative bacteria
scherichia coli, Serratia marcescens
Low urine pH (pH < 5.0)
seen most commonly in metabolic acidosis (kidney problem). Acidic urine is also associated with the ingestion of large amount of meat.
In addition to basic nutrients, ____ media contain one or more components that suppress the growth of some microorganisms without seriously affecting the ability of others to grow.
selective
which of the following contains DNASE Serretia marcescence or S. aureus
serratia Marcenscence Clreared spot indicated no DNA is there (degaraded by DNase)
glucose fermenter , unable to ferment lactose
shigella dysenteriae
Why are women more prone to UTIs than men
shorter urethra, their vagina/urethra is closer closer to rectum making it easier for bacteria to enter the bladder
You inoculated 0.01 ml of clean-catch voided urine sample on a nutrient agar plate and incubated at 35°C overnight. Next day, the number of colonies on the plate was 1,100. This urine sample has ____ bacteriuria. What's in the blank?
significant
type of germ that about 30% of people carry in their noses
staph aureus
which of the following is the major cause of nosocomial infections?
staphylococcus aureus
most frequent inhabitant of human surfaces, including skin and mucous membranes
staphylococcus epidermidis
Normally, urine is ___________ when excreted by the kidneys and stored in the urinary bladder.
sterile
true or false DNase produced and secreted by bacteria degrades DNA in the medium making clear circle.
true DNase produced and secreted by bacteria degrades DNA in the medium making clear circle. That indicates that the bacteria is DNase-positive
true or false Iron salt and sodium thiosulfate in KIA allow identification of Hydrogen sulfide producing bacteria in the medium.(BLACK precipitation)
true Iron salt and sodium thiosulfate in KIA allow identification of Hydrogen sulfide producing bacteria in the medium.(BLACK precipitation)
true or false Rapid urease production is characteristic of Proteus species,
true Rapid urease production is characteristic of Proteus species,
true or false Enzymes bind to their specific substrates and cause chemical change in them:
true Enzymes bind to their specific substrates and cause chemical change in them
true or false Obligate anaerobes don't have catalase.
true Obligate anaerobes don't have catalase.
true or false certain bacteria can be identified by examining the presence of a certain enzyme activity.
true certain bacteria can be identified by examining the presence of a certain enzyme activity. Occasionally, different species of bacteria have different sets of enzymes
true or false penicillium discovered by Alexander Flemmings can inhibit growth of staph aureus .
true penicillium discovered by Alexander Flemmings can inhibit growth of staph aureus .
true or false staph aureus is found among the flora of healthy individuals
true staph aureus is among the flora of healthy people
Indole test examines the presence of the enzyme ____ in bacteria. What is the name of the enzyme in the blank?
tryptophanase
indole test tests for
tryptophanase(enzyme)
Bacteria of the Proteus genus such as Proteus vulgaris produce _______________
urease
staphylococcus epidermidis and staphylococcus saprophyticus don't cause serious infections because they don't produce _____ factors such as hemolysins, coagulase, leukocidin
virulence
how should females wipe genitals for urine test .
wipe between folds of genitals front to back
how should males wipe for urine tests
wipe head of penis and opening pull foreskin back if uncircumcised
Very alkaline urine
(pH > 7.0) is suggestive of infection with a urea-splitting organism, such as Proteus mirabilis.
characteristics of staphylococci
-Gram-positive cocci -Catalase positive Colony irregular grape like cluster Hardy, facultative anaerobic organism.
steps to obtain accurate urine test
1.wash hands with soap and water . 2.handle cup carefully to avoid contaminating it do not touch the inside of cup or lid 3. wash genitals 4. start urinating into the toilet , midstream move cup in to catch some urine 5pull cup away before you finish urinating half full cup 6.put lid tightly around cup . label it properly
insignificant bacteriuria
100 to 1,000 per milliliter, not more than 10,000,
Which quadrant contains a gram positive bacteria?
3. did not grow any colonies( Staph . epidermis )
factors of cystitis in women
30% of women develop cystitis at some time during their lives. Short urethra Sexual intercourse Birth control devices such as diaphragms.
pH of human urine
4.5 to 8.2 (average 6.0)
coagulase
A bacterial enzyme that causes blood plasma to clot
R plasmid
A bacterial plasmid carrying genes that confer resistance to certain antibiotics.
Clean-Catch or Clean-Voided Techniques females
All labial surfaces must be thoroughly cleansed. The sterile container must be held in such a way that it does not contact with the skin or clothing. The first steam of urine is discarded. A midstream sample is collected. Close the container tightly and wipe the container with disinfectant
Infections caused by Staphylococcus aureus include all of the following
Bacteremia /sepsis Pneumonia Endocarditis Osteomyelitis
MacConkey Agar contains
Basal nutrients plus crystal violet, bile salt, lactose, and neutral red (pH indicator)
Antibiotic-inactivating enzymes
Beta-lactamases, carbapenemases, Kanamycin degrading enzyme,
ways to culture urine specimen
Catheterized urine specimen • Voided urine specimen
catherized urine specimen
Collecting urine sample directly from bladder by inserting a sterile polyurethane catheter tube into urethra and passing it up into the bladder.
cons of urine specimen collection
Contamination of urogenital flora into urine samples You must culture or analyze the sample immediately. You must obtain and report accurate result
What inhibits the growth of Gram-positive bacteria on MacConkey Agar?
Crystal violet and bile salt inhibit the growth of gram-positive bacteria.
Membrane-Damaging Toxins
Cytotoxins that disrupt plasma membranes causing cell to lyse
______________take the amino group out of amino acids.
Deaminases
Lactose fermenters
E. coli Enterobacter Klebsiella
You cultured Escherichia coli in a phenol red glucose broth overnight. The color of phenol red changed from red to yellow. What does it mean?
E. coli fermented glucose
factors of cystitis in males
Enlarged prostate: UTIs are unusual in men until about age 50, when enlargement of the prostate gland compresses the urethra and makes it difficult for them to completely empty the bladder. Catheterization: Medical conditions may require a urinary catheter to drain the bladder. Pathogen may create a biofilm either within or on the catheter.
gram positive bacterias that cause UTIs
Enterococcus spp., Staphylococcus saprophyticus and other coagulase- negative staphylococci, and Staphylococcus aureus
which of the following is the most frequent cause of UTI?
Escherichia coli
Mannitol Salt Agar(MSA) contains
Essential nutrient plus 7.5% NaCl, Mannitol, and phenol red (pH indicator)
alterations in target molecule
Modifications in penicillin binding proteins (PBPs), changes in ribosomal RNA,
What can detect Methicillin resistant genes
PCR test latex agglutination assay
Name the chemical component in phenyl ethyl alcohol agar that inhibits the growth of Gram-negative bacteria.
Phenyl thethyl alchohol ( selective ) Inhibits growth of Gram negative
________________________has been implicated in acute urinary tract infections in young women between 16 to 25 years of age.
Staphylococcus saprophyticus
Examples of catalase positive anaerobes
Streptococcus pyogenes and Enterococcus faecalis
all the followings are Folliculitis Pimples, furuncles (boils), carbuncles, and impetigo in skin Pneumonia, pyelonephritis, osteomyelitis, meningitis, and endocarditis. Infections of the sinuses (sinusitis) and middle ear (otitis media).
Symptoms of S. aureus infection
Clean-Catch or Clean-Voided Technique for males
Thoroughly wash the glans of the penis. Discard the first stream of urine. Collect a midstream portion in a sterile container. If the outside of container has been soiled with urine, it must be wiped clean with disinfectant before being handled further
what is the purpose of indole test ?
To distinguish bacterial species by their production of indole
what is the purpose of KIA ?
To observe how a single medium can be used to determine multiple biochemical reactions of bacteria
"Any microorganism is potentially pathogenic if it enters a susceptible host." Is it true or false?
True
If the microorganism produces _______________, it digests starch in the starch agar, and Gram's iodine will not form blue-purple color.
amylase
What is the enzyme that hydrolyzes starch?
amylase
The presence of bacteria in voided urine is _________.
bacteriuria
why can some staphyloccocci grow on mannitol salt agar?
because they are halotolerant
staphylococcus aureus is
beta-hemolytic
Enzymes
biological catalysts of biochemical reactions.
The test should not be performed with organisms growing on a ________________medium because catalase is found in red blood cells.
blood containing
bascillus subtilis
is amylase positive degragres starch
Streptococcus pyogenes
is an hemolysin bacteria
Purpose of DNase test?
is to see if the bacteria has the ability to produce the DNase enzyme
Leukocidins
kill phagocytic leukocytes
KIA contains abundant of___________ , but small amount of _____________
lactose glucose
Staphylococcus epidermidis
may cause infections if they get past barriers through wounds ect may be dangerous to immunocompromised people
cons of Catheterized urine specimen
may introduce microorganisms into the bladder that could result in infection and cystitis. So, it has a risk.
Many hospital strains of S. aureus are resistant to most of the commonly used antibiotics, especially methicillin. These strains are called
methicillin- resistant S. aureus (MRSA).
3 ways people get UTIs
microorganisms in the bloodstream are deposited to kidneys from infection site producing pyelonephritis Bacteria on the outside or at the end of urethra travel to bladder causing cystitis Microorganism in the urethra are introduced in the bladder with catheters or cystoscopes
changes enzymes cause in their substrate
modification, breaking down , combine molecules together
voided urine specimen
more commonly collected for urine culture.
Genetic Transfer
movement of DNA from one bacterium to another by transformation, transduction, or conjugation
non-hemolytic streptococci
no effect on red blood cells
pros of urine specimens collection
no risk of infection
