deck_5545894 Flashcards
Explain steps of the gram stain
- crystal violet to stain peptidoglycan- add iodine to stick stain better- ethanol 95% to clear stain- safranin 0.25 % stain gram - cells pink; no effect on gram + cell ethanol not able to wash away stain, remains blue
function of iodine in the gram stain
- iodine is a mordant that fixes the crystal violet to the bacterial cell wall
what are the dyes used in the endospore stain
malachite green and safranin .5%
what color are the endospores stain
- green
what is the function of steam used in the endospore stain
- to help the dye, malachite green penetrate into endospore
what is the principle dye used in the acid fast stain
- Ziehl’s carbolfuchsin
what color are the acid fast cells
pink
what is the first step in the identification of an unknown? why is this important
- making a streak plate/ it’s important because of obtaining an isolated colony
why is the aseptic technique important when you transfer mmicrobes
to reduce the risk of contamination
why are pour plates used in determining bacterial populations in food
- to make a viable count (find coliform count and find total bacterial count
Indole- medium- reagents- positive reaction- negative reaction- purpose of the test
- tryptone broth- Kovacs reagent- red +- yellow – purpose: to determine whether bacterium can utilize tryptophan producing indole as a waste product
Methyl red- medium- reagents- positive reaction- negative reaction- purpose
- MR-VP- Methyl red- Red +- Yellow (- no change)- purpose: to identify bacterial ability to produce acidic by-products of glucose fermentation (mixed acid fermentation of glucose)
Voges-Proskauer- medium- reagents- positive reaction- negative reaction- purpose
- MR-VP- KOH and a-naphthol- brick red +- yellow (- no change)- purpose to determine bacterial ability to produce non-acidic byproducts (acetoin) from glucose
Citrate - medium- reagents- positive- negative- purpose
- simmon’s citrate agar’- Bromthymol blue (in the medium)- blue +- green – purpose: to determine the ability of an organism to use citric acid as a source of carbon
KIA- see hard copy
- see hard copy# 31 to 37
in KIA what is the pH indicator
- Phenol Red
In KIA what does the black color indicate?
- production of H2S
In KIA, how do you tell if any tube produced gas in this test, and what kind of gas can be produced?
the agar is lifted or has cracks
What does SIM stand for?
- Sulfide-Indole-Motility
What three tests are included in SIM media?
- sulfur reduction: sulfide production results from the production of H2S from the amino acid cysteine- Production of Indole: from the breakdown of tryptophan- Motility: the ability of the bacteria to swim through a semi-solid medium
40-46 check hard copy
check
for Nitrate Reduction: except the color, is there any other way that you can determine whether it is positive reaction?
- yes. a durham vial is present to capture any gas (N2) produced - an indication of denitrification
(blood agar) Explain differential. how does it function as a differential medium?
A differential medium allows the distinction between bacteria that grow on it
what is blood agar medium used for?
blood agar permits the detection of groups of bacteria that produce hemolysins
In Blood agar what does the clear areas indicate? how are they formed?
- clear area indicate B-Hemolysis
- they are formed by the complete destruction of RBCs and hemoglobin
What type of medium is Mannitol Salt Agar. explain each function
- selective: selectively grow staphylococci
- differential - differentiate pathogenic species from non-pathogenic species
How does the genus grow in Mannitol Salt Agar
- it tolerates the salinity of the medium
in mannitol salt agar which carbohydrate was fermented in the yellow colored area?
- mannitol
- what are the organisms used in our lab on each area of the mannitol salt agar?
- Staphyloccoccus aureus (yellow)
- Staphyloccoccus epidermidis (pink)
What are the three parts and its purpose of the water analysis
- Presumptive test (MPN test)
- confirmed test
- completed test
What medium is used in the MPN test
- Lauryl sulfate lactose broth
What indicates a positive result in the mpn test? where did it come from
- gas formation in a durham tube
- lactose fermentation
what is coliform
- indicator organisms which indicate the presence of human fecal waste
- gm negative non-spore forming, facultative rods which ferment lactose
What medium is used in the second part of coliform test
EMB (Eosin Methylene Blue) Agar
How is e. coli shown in EMB medium
- Metallic green sheen
What tests are used in the third part of the water analysis
- IMViC test
- what medium is used for coliform dilution factors
- VRBA (violet red bile agar)
- why do you overlay when you use SIM medium?
- to prevent growth of aerobes
What does SPCA stand for?
- Standard Plate Count Agar
Do you overlay SPCA? why or why not?
- NO. to count the number of aerobic and facultative bacteria as well
What is the purpose of using SPCA
- total bacterial count
What are two microbes principally involved in the yogurt production?
- Streptococcus thermophilus
- Lactobacillus bulgaricus
What purpose do the microbes serve in yogurt?
- they produce lactic acid as a byproduct of lactose fermentation, and lactic acid causes the casein in the milk to denature and thus causes the milk to curdle
What type of medium is MacConkey Agar. explain how it works
- Selective for gram negative (bile salt and crystal violet inhibit growth of Gram positive/ differentiate lactose fermentds from non-lactose fermenters
- What are the ingredients of MacConkey Agar
- lactose
- neutral red
- bile ssalts
- crystal violet
Which carbohydrate did the pink colonies ferment?
- lactose
What is the pH indicator of MacConkey agar
- neutral red
Where is Borrelia burgdoferi found in the human body? (check h.c for picture)
- Blood and lymph
What disease does Borrelia burgdoferi cause?
- lyme disease
What is the mode of transmission of Borrelia burgdoferi
- Deer tick
What are the symptoms of Borrelia burgdoferi
- red rings/kinky joints
Explain gram reaction and mophology of Neisseria gonorrhea (check for picture)
- gram negative cocci
Where can you find Neisseria gonorrhea in the human body?
- it attaches to the urethral or vaginal epithelial cells
what disease does the Neisseria gonorrhea cause?
- gonorrhea…PID
How is Neisseria gonorrhea transmitted?
- STD
What are the symptoms of Neisseria gonorrhea
- lower abdominal or pelvic pain
- conjunctivitis
What is the mode of transmission of Bacillus anthracis
Endospores
what disease does Bacillus anthracis cause?
- anthrax
- woolsorters’ disease
what are the characteristics of Clostridium botulinum
- gram positive, strict anaerobe, endospore forming
What disease does Clostridium botulinum cause?
- food poisoning
What are the characteristics of Treponema pallidum
- gram negative spirochete
Where can you find Treponema pallidum?
- mucous membrane
Which disease does Treponema pallidum cause?
- syphilis
Where is Clostridium tetani commonly found in our environment?
- soil and animal feces
What diesease does Clostridium tetani cause?
- Tetanus (lockjaw)
What is the symptoms of Clostridum tetani
- Muscle contraction
What vaccine can you get to prevent Clostrdium tetani infection?
- TDaP
how is HIV diagnosed?
- ELISA: for detection
- western blot: for confirmation
what does elisa stand for?
- enzyme-linked immunosorbent Asssay
what do PCR do?
- amplify a segment of DNA
how does a western blot confirm the presence of HIV antibodies?
- using gel electrohoresis, it separates or denatures proteins by the length of the polypeptide
- match with a patient control
what are the similarities or different features of neutrophils and monocytes?
- both are leukocytes
- neutrophils: granulocyte, muli nuclie
- monocyte: non-granulocyte, large nuclei
