Quiz 4 Flashcards
What is the purpose of the motility test?
To determine whether bacteria are motile (can move)
Why do we have a low percentage of agar in the motility test?
Semi-solid for detection of motility
What is the substrate in the motility test?
Triphenyltetrazolium chloride (TTC)
- Detects bacterial growth - show us where the bacteria grows
What is the enzyme in the motility test?
Various endoenzymes
- Function as reductase to reduce TTC
- Reductase found in all bacteria
What is the reduced form of TTC?
Formazan
What is a positive and negative in the motility test?
Positive: fuzzy appearance migrating away from the stab line
Negative: growth only along stab line
- Able to grow where inoculated but not motile away from stab line
What is the purpose of the nitrate reduction test?
To determine whether bacteria can use nitrate (NO3) as the final electron acceptor during anaerobic respiration
What is the substrate of the nitrate reduction test?
Nitrate no3-
What is the enzyme used in the nitrate reduction test?
Nitrate reductase
What is the product of the nitrate reduction test?
Nitrite no2-
What are the reagents used in the nitrate reduction test to detect nitrite and what color does it turn for a positive test?
Reagents A and B
- Turns red
What is ammonification?
The production of ammonium
What is denitrification?
Loss of biologically available nitrogen; occurs by release of nitrogenous gases
What is the one true negative in the nitrate reduction test?
Turns red after zinc is added
- Reducing agent that reduces any remaining nitrate into nitrite
What is the function of zinc in the nitrate reduction test?
A reducing agent, will cause nitrate to gain electrons
- If turns red, bacteria don’t use nitrate
- If remains clear, full reduction of nitrate occurred by bacteria
What is an acidophile?
Grows best at low pH
What is a neutrophile?
Grows best at neutral pH
What is an alkaliphile?
Grows best at high pH
What does osmotolerant mean?
Grows at a range of salt concentrations
Where do psychrophiles grow?
Grow below freezing and optimally in refrigerator but not at room temperature
Where do psychrotrophs grow
Grow in refrigerator and room temperature but not at human body temperature
Where do mesophiles grow?
Grow at room temperature and body temperature and a little above body temperature
Where do thermophiles grow?
Not at body temperature but above 40 to 80 degrees
Where do extreme thermophiles grow?
Boiling temperatures
What is an example of a psychrotroph?
Listeria monocytogenes
What is the purpose of the steam sterilization?
To determine if the autoclave is working properly to sterilize instruments, media,etc
What are the minimum operating conditions for the steam sterilization test?
120 degrees celsius for 15 minutes at 15 PSI
What is in the kilit ampule?
Bacillus stearothermophilus endospores
- heat resistant organism
Bromocresol purple - pH indicator
Purple = alkaline
Yellow = acidic
Glucose - fermentation
- If organism survives, it will ferment glucose and produce acidic products
What would a sterile and non-sterile solution look like?
Not sterile = yellow
- Acidic meaning glucose was fermented by bacteria
Sterile = purple
- Alkaline meaning glucose was not fermented and organism died in autoclave
What is the purpose of the kirby bauer method (disk diffusion)
To perform a culture and antibiotic sensitivity test on an organism
How is the Kirby bauer method a standardized test?
Uses a mueller-hinton agar
pH = 7.2-7.4
Soft agar for diffusion
4mm in depth (lateral diffusion)
Plates incubated at 37 degrees celsius
Incubate for 18 hours
Amount of drug
What is being measured for the readout for the kirby bauer?
Zone of inhibition - clear to clear
- Measured in mm
What are the 3 levels of susceptibility?
Sensitive = a normal dose of an antibiotic is effective
Intermediate = a higher than normal dose of an antibiotic is required
Resistant = no acceptable dose of antibiotic is effective
Are all bacteria found within the clear area around the disks dead? T/F
No this would be false
Are gram negative or gram positive bacteria more resistant to antibiotics?
Gram negative
Which organisms are most resistant to least resistance?
Prions
Endospores of bacteria
Mycobacteria
Cysts of protozoa
Vegetative protozoa
Gram-negative bacteria
Fungi, including most fungal spores
Viruses without envelopes
Gram positive bacteria
Viruses with lipid envelopes
What is a broad spectrum drug?
Kills or inhibits both gram + and gram - bacteria
What is a narrow spectrum drug?
Kills or inhibits ONLY specific types of bacteria, like only gram + bacteria
What is drug synergy?
two drugs display greater effectiveness together than either drug alone
What is the purpose of the membrane filter technique?
To test a water sample for the presence of coliform bacteria (presumptive test)
What does presumptive mean?
Results or data that has a high confidence (>95%) of accuracy
What is a coliform?
Gram - rod bacteria that ferment lactose to produce acid and gas
Why is the presence of coliforms a problem in water?
Coliforms are an indicator of sewage/fecal contamination that may contain pathogens (viruses, worms, protozoans, etc)
How big are the pores in the grid on the membrane filter and how is this relevant to bacteria?
Pores are 0.45 micrometers in size
Most bacteria are 1-5 micrometers in size
- Bacteria would be stuck on filter and would not pass through
What is the purpose of the multiple tube fermentation lauryl tryptose broth?
To test a water sample for the presence of coliform bacteria (confirmatory test)
- Confirm if water contains coliforms
What are the selective ingredients in the LTB broth?
Sodium lauryl sulfate
- Inhibits gram + growth
What are the differential ingredients in the LTB broth?
Lactose
What is a positive and negative in the LTB broth?
Positive: growth/turbidity + gas
Negative: no growth or growth + no gas
What ingredients are differential in the BGLB broth?
Lactose
What ingredients are selective in the BGLB broth?
Oxgall -bile (gallbladder of ox)
- Brilliant green dye
What is a positive and negative in the BGLB?
Positive: growth and gas produced
Negative: no growth or growth + no gas
What is the purpose of multiple tube fermentation endo agar?
To test a water sample for the presence of coliform bacteria (presumptive test)
What are the selective ingredients in the endo agar?
Sodium sulfite and basic fuchsin
- Inhibit gram + but promote gram - growth
What are the differential ingredients in the endo agar?
Lactose
What is the final electron acceptor in alcohol fermentation?
Acetaldehyde
What is a selective medium?
Inhibits certain types of organisms from growing, while allowing the growth of other types
What is a differential medium?
Used to differentiate closely related bacteria species (for example, changes color based on differences in bacterial metabolism)
What does a green metallic sheen mean on the endo agar?
Gram - bacteria grew
Darkened with acetaldehyde and turned metallic green with low pH - rapid fermenter of lactose
Presumptive E. coli
What does a dark pink/red mean on the endo agar?
Gram - bacteria grew
Darkened with acetaldehyde and did NOT turn metallic green
- pH did not lower
- Slow fermenter of lactose
Presumptive klebsiella pneumoniae (pneumonia)
What does a light pink/colorless mean on the endo agar?
Gram - bacteria grew
Did NOT darken with acetaldehyde
- Did not ferment lactose
- Used peptones
Presumptive salmonella typhi (typhoid fever) or shigella dysenteriae (shigellosis)
Entamoeba histolytica - disease it causes
Amebic dysentery
- Diarrhea
Entamoeba histolytica - infective stage and mode of transmission
Transmitted through fecal and oral route
- Quadranucloate cyst (infections)
- Ingestion (hatches in small intestine)
Entamoeba histolytica - mode of motility
Pseudopod
Entamoeba histolytica - symptoms
Bloody diarrhea (penetrate lining of intestine and causes ulcers)
Entamoeba histolytica - treatment
Metronidazole
Entamoeba histolytica - method of diagnosis
- Some people are asymptomatic carriers (only 10-20% of infected people)
- Stool sample to look for cysts or trophs
Entamoeba histolytica - stages in the life cycle
Cysts - up to 4 nuclei
Trophs - 8 trophs
Balantidium coli - disease it causes
Balantidiosis
- diarrhea
Balantidium coli - infective stage and mode of transmission
Fecal and oral transmission
- Eating contaminated food or drinking water
Balantidium coli - mode of motility
cilia
Balantidium coli - symptoms
Often asymptomatic but can have bloody diarrhea, weight loss, stomach pain, etc.
Balantidium coli - treatment
metronidazole
Balantidium coli - method of diagnosis
Stool sample looking for trophs or cysts in stool sample
Balantidium coli - stages in the life cycle
Cyst - kidney shaped nuclei
Troph - oval
Giardia lamblia (intestinalis) - disease it causes
Giardiasis
- Backpacker’s diarrhea
Giardia lamblia (intestinalis) - infective stage and mode of transmission
Beavers are carriers and shed cysts in the water during a bowel movement
- Backpacker’s drink untreated wilderness water
Giardia lamblia (intestinalis) - mode of motility
flagella
Giardia lamblia (intestinalis) - symptoms
Watery diarrhea, fatigue, nausea, flatulence, weakness, weight loss, and abdominal cramps
Giardia lamblia (intestinalis) - treatment
metronidazole
Giardia lamblia (intestinalis) - method of diagnosis
Stool sample to verify cysts and trophs
Giardia lamblia (intestinalis) - stages in the life cycle (cysts, troph, etc)
cysts - up to 4 nuclei
Troph - 2 nuclei + 4 pairs of flagella
Trichomonas vaginalis - disease it causes
Trichnomiasis (STI)
Trichomonas vaginalis - infective stage and mode of transmission
Sexually transmitted infection
Trichomonas vaginalis - mode of motility
flagella
Trichomonas vaginalis - symptoms
Many people asymptomatic
Itching, burning, redness, discomfort w/ urination, change in vaginal discharge
Trichomonas vaginalis - treatment
metronidazole
Trichomonas vaginalis - method of diagnosis
Molecular testing and wet mount of discharge fluid to look for troph
Trichomonas vaginalis - stages in the life cycle
Troph - large nucleus w/ 4 flagella
