Lab Final Flashcards
How can infections in the urethra and bladder be detected
by obtaining a clean-catch sample of urine
What tests are used to characterize catalase-negative Gram-positive cocci?
- Hemolysis test
- Bile esculin test
- PYR test
- CAMP test
- Antibiotic susceptibility test
Transduction
The addition of DNA to a bacterium via a prophage
MPN test: Does the presence of gas in a presumptive test mean that coliform bacteria are present?
No, a confirming test must be done
Streptolysin O
is oxygen liable and cannot perform hemolysis in the presence of oxygen
reservoir
a place where infectious agents can multiply
2 ml of food is added to 8 ml of water, what is the final dilution?
2:10 or 1:5
What are the characteristics of Staphylococcus sp.?
- Gram-positive cocci in singles, pairs, tetrads or clusters
- catalase positive
- facultative anaerobes
- most are oxidase negative
- can grow in 6.5% NaCl
- Most produce acid from glucose
- Most are resistant to bacitracin
- Hemolytic reactions vary by species
- Key pathogen is S. aureus, known to be the causative of toxic shock syndrome and a variety of other infection
Antibiotic susceptibility
Antibiotic sensitivity or antibiotic susceptibility is the susceptibility of bacteria to antibiotics.
Streptokinase
prevents blood clots and disintegrates them
What are the symptoms of cystitis?
dysuria (frequent and painful urination) and pyuria (the presence of leukocytes and pus in the urine)
What is important to remember when performing a hemolysis test with Streptococci or Enterococci?
you must streak and stab the blood agar plate; a uniform lawn is made and stabs are made with the loop. Stabs allow bacteria to be introduced to an anaerobic, so you can better determine if the hemolysin is Streptolysin S or Streptolysin O
In the MPN assay the 95% confidence limits are ___________.
The upper and lower limits of bacteria that may be in a water sample
DNase
an enzyme that breaks down DNA
What are the characteristics of Enterococcus?
- Formerly members of Streptococcus
- Gram-positive cocci to ovoid cocci in singles, pairs or short chains
- Catalase negative
- Oxidase negative
- Facultative anaerobes
- Ferments to lactic acid without gas
- Can grow in 6.5% NaCl
- Can grow in bile esculin
- Most are PYR positive
- Most species are commensals or opportunistic pathogens
- Key pathogen is Enterococcus faecalis
- and - strand
- progametangia
- gametangia
- zygosporangium
- zygospores
How was the GFP protein put into the bacteria?
it was done with plasmid vectors; pGLO plasmids
What is the difference between Antiseptics and Disinfectants?
Antiseptics are used on living tissues, disinfectants are used on non-living surfaces; sometimes a chemical can be an antiseptic or disinfectant depending on the concentration of the chemical.
What is the arabinose promoter called
Pbad
What are the asexually produced spores of Rhizopus called?
Sporangiospores; they are produced in sporangia at the end of sporangiophores
Fibronectin-binding protein
an adhesin/binding protein that allows bacteria to attach to a host’s epithelial cells
Some members of Enterobacteriaceae are ____________ like E.coli which are normal microbiota in mammalian intestinal systems, others like Shigella sp. are always considered to be ____________ to humans
- Commensals
- True pathogen
When is it okay to use an intermediate antibiotic?
never
What happens if cystitis is not properly treated?
In the pGlo experiment what substance was used to make the E.coli’s membranes permeable to the plasmids?
CaCl2
Hyaluronidase
hydrolyzes hyaluronic acid in connective tissue
Fomites
objects or materials that are likely to carry infection, such as clothes, utensils, and furniture.
MPN: In the last set of 3 10 ml lactose tubes how much broth is removed and how much water is added?
0.1 of an ml is discarded to make 9.9 ml tubes and 0.1 ml of water source is added
E
Erythromycin
Staphylococci, Streptococci, and Enterococci are _________
_____________.
- pyogenic
- Gram-positive bacteria
1 ml of 1:10 dilution is added to 9 ml of water, then 1 ml of that solution is added to 99 ml of water, what is the final dilution?
1:10,000
CAMP test
This test can be performed on catalase-negative gram-positive cocci to differentiate the bacterium Streptococcus agalactiae from other bacteria. The CAMP test is a test to identify Group B β-streptococci based on their formation of a substance (CAMP factor) that enlarges the area of hemolysis formed by β-hemolysin from Staphylococcus aureus. It is frequently used to identify Group B Strep (Streptococcus agalactiae).
Sepsis
the growth of any microorganism
Streptolysin S
is stable in the presence of oxygen and can still perform hemolysis in an oxygenated environment
Describe the life cycle of Plasmodium vivax. What type of transmission is described?
- Transmission to host by mosquito in sporozoite form
- Schizogony of P. vivax occurs in liver of the host or RBCs (Schizonts); merozoites are produced by schizonts
- Merozoites released into bloodstream to infect red blood cells
- Merozotie enters ring stage in RBC (Trophozoite)
- Trophozoite grows becomes a schizont which divides, producing merozoites
- Merozoites lyse RBC
- Merozoites mature into gametocytes (sexually mature) and are ingested by mosquito vector or stay merozoites and infect other RBCs
- inside mosquito gametocytes unite to form a zygote
- Zygotes mature into sporozoites and are ready to be transmitted to another human
* this is an example of biological transmission
Bile esculin test
The bile esculin test is a selective and differential medium used to detect enterococci and certain types of streptococci. Bile inhibits the growth of some gram-positive bacteria. If bacteria grow and can hydrolyze esculin into esculetin and dextrose, the esculetin interacts with ferric citrate in the medium and forms a brown/black precipitate after incubation.
An infection of the urethra or urinary bladder
Urinary Tract Infection (UTI)
what is the range of CFUs that is statistically acceptable to use when determining the number of bacteria present in 1.0 g of a food sample?
30-300 CFUs
How do molds reproduce?
via sexual and asexual spores
MPN index per 100 ml refers to
the most likely amount of bacteria in a 100 ml sample of water
How do you calculate the amount of bacteria on a plate?
Number of colonies on plate x reciprocal of the dilution of sample = # bacteria/ml
What tests are typically used to characterize Gram-negative bacteria?
- Indole test
- Simmon’s citrate
- MR test
- Urease test
- KIA test (Kligler Iron agar)
Novobiocin test
an antibiotic sensitivity test used to identify staphylococcus sp.
Schistosoma mansoni Lifecycle
- Schistosomula
- Adult Blood flukes (paired)
- Egg
- Miracidium
- Sporocyst
- Cercaria
Because Fungi are absorptive heterotrophs how do they obtain nutrients?
they secrete exoenzymes that digest nutrients outside the cells, nutrients are then absorbed by the fungus.
Intermediate host
host in which asexual reproduction takes place
Lac operon: an inducible operon which controls the gene expression of the enzymes needed to break down lactose in bacteria.
- RNA polymerase
- Operator
- Promoter
- Structural genes
- Regulatory gene
- Repressor protein
- mRNA
- Lactose
Hyphae can be __________
separate; walls separate adjacent cells, or nonseparate; walls are absent between adjacent cells
Platyhelminths
flat worms
A Streptococci bacterium which causes infection in newborns passing through the birth canal.
Streptococci agalactiae
- Organism: Ascaris lumbricoides
- Stages: egg, larvae, adult worm
- Infective Stage: Embryonated egg
- Reservoirs: Humans, soil, inanimate objects
- Mode of Transmission: Fecal-oral route
- Diseases: Ascariasis
- Symptoms: may be asymptomatic, bloody sputum, cough, fever, abdominal discomfort
What is the primary way in which nosocomial infections spread?
Nurses, doctors, and other healthcare professionals fail to wash their hands properly or sterilize equipment used in physical examinations, patients may already be immunocompromised by disease or trauma and are more susceptible to infections
What Domain and kingdom do helminths belong to?
Eukarya and Animalia
What indicator was used in the epidemic simulation? what color indicated a positive for infection? What was the pH of the original infectious broth?
Phenol red was the pH indicator used in the epidemic simulation, a yellow color change indicated infection. The pH of the original infectious broth was acidic below 6.8.
Why is a lactose test performed?
The purpose of a lactose test is to determine whether a bacterium can ferment lactose or not. Bacteria that can ferment lactose will produce acidic end products, which will cause the pH indicator phenol red to turn yellow. In the case of the KIA test the combined acidic end products from glucose and lactose fermentation will cause the whole test tube to turn yellow indicating that the bacterium can ferment lactose.
- Organism: Taenia sp.
- Stages: Egg, cysticerci, adult tapeworm
- Infective Stage: cysticerci
- Reservoirs: Humans, pigs, contaminated food and water
- Mode of Transmission: Vehicle-borne (undercooked beef and pork)
- Diseases: Taeniasis, cysticercosis
- Symptoms: may be asymptomatic, abdominal pain, loss of appetite, weight loss, upset stomach
VRE
Vancomycin-resistant enterococci (VRE) are a type of bacteria called enterococci that have developed resistance to many antibiotics, especially vancomycin. Enterococci bacteria live in our intestines and on our skin, usually without causing problems. But if they become resistant to antibiotics, they can cause serious infections, especially in people who are ill or weak. These infections can occur anywhere in the body. Some common sites include the intestines, the urinary tract, and wounds.
Vancomycin-resistant enterococci infections are treated with antibiotics, which are the types of medicines normally used to kill bacteria. VRE infections are more difficult to treat than other infections with enterococci, because fewer antibiotics can kill the bacteria.
Most fungi are Saprophytic, what does saprophytic mean?
Saprophytes are more generally plants, fungi, or micro-organisms that live on dead or decomposing matter.
NB
Novobiocin
Is S. epidermidis pathogenic?
It is capable of causing disease in humans and is frequently the cause of nosocomial infections
What Polysaccharide is found in a fungal cell wall?
Chitin
10 ml of food is added to 10 ml of water, what is the final dilution?
10:20 or 1:2
Animals are _________.
Ingestive Chemoheterotrophs
A plate with +pGLO bacteria with LB, ampicillin and arabinose should have__________.
Some colonies which are resistant to ampicillin and glow under UV light
MPN: In the first sets of 3 10 ml lactose tubes how much broth is removed and how much water is added?
No water is removed, but 10 ml of water is added to 10 ml of lactose broth
Plate count method
a way to approximate the number of microbes in a reservoir; serial dilutions are made and plates are inoculated with different dilution ratios. The number of cfus are counted in each dilution then the the concentration of bacteria will be calculated using the number of cfus and the dilution factor.
Bacteriocidal
Chemicals which kill bacteria
Gamma hemolysis
non-hemolysis; no change to medium. Staphylococcus, Streptococcus and Enterococcuse may be gamma hemolytic.
What happens when lactose/arabinose is not present?
The repressor protein is still attached to the operator and RNA polymerase cannot attach to the promoter and begin transcription of the structural genes
many streptococci cause disease but which is most virulent?
Streptococcus pyogenes
Prostatitis
Inflammation of the small walnut-shaped gland (prostate) that produces seminal fluid.
What is MRSA?
a strain of S. aureus which is resistant to methicillin and is coagulase positive
+pGLO
had the pGLO plasmid
What major diseases does Viridans Streptococci cause?
- Subacute bacterial endocarditis
- bacteremia
- meningitis
- gingivitis
- abscesses
- osteomyelitis
- empyema
Food is a combination of __________.
reservoirs
What is the most common pathogen in the Staphylococcus genus?
Staphylococcus aureus
What cellular arrangement do Streptococci and Enterococci assume when grown in liquid broth?
a chain-like cell arrangement
Schizogony
asexual reproduction by multiple fission, found in some protozoa, especially parasitic sporozoans.
Hyaluronic acid capsules
Allows bacteria to avoid phagocytosis and hide its antigens
How does sexual reproduction occur in Rhizopus?
different mating types + and - strands respond to chemicals in the environment that are released by the opposite mating type , this causes the + and - strands to grow hyphae towards eachother. Specialized ends on these hyphae are called progametangia; progametangia make contact and they separate from the rest of the filiment and gametangia are formed. Gametangia fuse togther to form a zygosporangium. Gametoangia nuclei fuse to make a diploid zygote, after under going meiosis the nuclei become haploid, and haploid zygospores are formed. Zygospores are released at the end of the sporangiophore.
1 ml of food sample is added to 9 ml of water, what is the final dilution?
1:10
Coagulase
The enzyme coagulase allows bacteria to form clots from fibrin found in blood plasma. Organisms that produce coagulase can form protective barriers of fibrin around themselves, making themselves highly resistant to phagocytosis, other immune response, and some antimicrobial agents.
Why is a Simmon’s citrate test performed?
This test determines whether a bacterium can utilize citrate as its sole carbon source. If the bacteria can use citrate as a carbon source they will use ammonia salts in the medium; this will produce ammonia which will lower the pH of the media and cause the bromthymol blue in it to turn blue.
What are the classes of the phyla platyhelminths?
- Turbellaria
- Trematoda (human pathogens)
- Cestoda (human pathogens)
How was the arabinose operon modified?
The araB, araA, and araD genes were replaced with the GFP gene, the bacteria can no longer digest arabinose, but the bacteria will glow in the presence of arabinose
What are the characteristics of bacteria in the family Enterobacteriaceae?
- Gram negative
- Facultative anaerobes
- Oxidase negative
- Acid production from glucose (with or without gas)
- Most are catalase positive
- Most reduce nitrate to nitrite
- Peritrichous flagella if motile
- bacilli or cocobacilli
- most form greyish colonies
A Streptococci bacterium which is the number one cause of dental carries.
Streptococcus mutans
If the zone of inhibition for E.coli is 12mm for disinfectant A and 4mm for disinfectant B, which one is more effective? Explain.
Disinfectant B is more effective because it has a larger zone of inhibition than disinfectant A. A larger zone of inhibition indicates that the substance in the disk is more toxic to the bacteria and the bacteria are less likely to be resistant to it.
Why is it important to use a MacFarland 0.5 for Kirby-Bauer antibiotic testing?
The appropriate concentration of bacteria must be inoculated onto the agar plate so that that effect of the antibiotics can be accurately determined.
Why do different bacterial species respond differently to different antibiotics?
Different species of bacteria can respond differently to the same antibiotic because each species has different DNA coding for different traits, these traits can make a bacterium vulnerable or impervious to an antibiotic’s mechanism of action.
What types of bacteria would be on your hands after washing them?
your normal microbiota
- Organism: Enterobius vermicularis
- Stages: egg, larvae, adult worm
- Infective Stage: Embryonated egg
- Reservoirs: Humans
- Mode of Transmission: Fecal-oral route
- Diseases: Enterobiasis (pinworm infection)
- Symptoms: itchy anal region
Cystitis
inflammation of the urinary bladder
What are the virulence factors of Salmonella and what are some illnesses it can cause?
- Fimbriae that allow adherence to intestinal mucosa
- Ability to transverse intestinal mucosa
- Enterotoxins that cause gastroenteritis
- Salmonellosis
- gastroenteritis
- typhoid fever
- non-typhoidal bacteremia
- Carrier state
A plate with +pGLO bacteria with LB and ampicillin should have__________.
some growth of amp resistant bacteria should not be a lawn
Cestodes
often called tape worms
Definitive host
host in which sexual reproduction takes place
Why is a glucose gas test performed?
This test determines if a bacterium can produce gas while fermenting glucose. When bacteria produce gas while fermenting glucose it displaces broth in a durham tube or breaks up the agar in a KIA test to form gas bubbles or pockets.
EMB plates
Eosin Methylene Blue agar
Enterococci are the most common cause of __________ infections, especially when medical devices and prolonged antibiotic use are involved.
Nosocomial
Fungal diseases in humans are often ____________.
oppertunistic
Pandemic
a global or national epidemic
What is the protein that causes the transformed bacteria in the pGlo experiment to fluoresce green under UV light?
GFP (Green Fluorescent Protein)
MacFarland 0.5
In microbiology, McFarland standards are used as a reference to adjust the turbidity of bacterial suspensions so that the number of bacteria will be within a given range to standardize microbial testing. An example of such testing is antibiotic susceptibility testing by measurement of minimum inhibitory concentration which is routinely used in medical microbiology and research. If a suspension used is too heavy or too dilute, an erroneous result (either falsely resistant or falsely susceptible) for any given anti microbial agent could occur.
Original McFarland standards were mixing specified amounts of barium chloride and sulfuric acid together. Mixing the two compounds forms a barium sulfate precipitate, which causes turbidity in the solution. A 0.5 McFarland standard is prepared by mixing 0.05 mL of 1.175% barium chloride dihydrate (BaCl2•2H2O), with 9.95 mL of 1% sulfuric acid (H2SO4).
Now there are McFarland standards prepared from suspensions of latex particles, which lengthens the shelf life and stability of the suspensions. The standard can be compared visually to a suspension of bacteria in sterile saline or nutrient broth. If the bacterial suspension is too turbid, it can be diluted with more diluent. If the suspension is not turbid enough, more bacteria can be added.