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Practical II
Microbiology Lab Practical 2
| Question | Answer |
|---|---|
| chemical control of microorganisms includes | antimicrobial chemicals, disinfectants and antiseptics |
| chemical controls of microorganisms can be used on | surfaces that need to be decontaminated, objects, skin, and other human/animal tissue |
| what are the two different mechanisms of chemical control of microbes | 1) alteration of cell walls/cytoplasmic membrane, 2) interference with proteins/structure of nucleic acid |
| there are two actions of antibacterial/antimicrobial agents, what are they | static (inhibit growth) and cidal (killing) |
| what is the disc diffusion assay | a form of testing antibiotics/antimicrobials, it places filter discs impregnated with chemicals on an inoculated Petri dish, then creates a zone of inhibition |
| antimicrobial chemotherapy is the use of ___________________ to inhibit or kill microorganisms | chemicals |
| antimicrobial chemotherapy is based on ___________________ | selective toxicity |
| what is selective toxicity | the agent used must kill (or inhibit) the microorganism in question without harming the host |
| how does the selective toxicity kill or inhibit the microorganism | the antimicrobial must interact with some function or it must interact with some structure of the microorganism |
| to treat infections caused by Prokaryotes many antimicrobial chemicals | prevent peptidoglycan synthesis or inhibit bacterial enzymes (specifically DNA gyrase and RNA polymerase) |
| why would antibiotic medications work against prokaryotes but not human cells | human cells do not contain peptidoglycan molecules or DNA gyrase; and the human RNA polymerase is structurally different than those found in Prokaryotes |
| what are the two types of chemotherapeutic classes | antibiotics and antimicrobial chemotherapeutic chemicals |
| what is the difference between antibiotics and antimicrobial chemotherapeutic chemicals | antibiotics are byproducts of bacteria for the purpose of killing competing microbial organisms, antimicrobial chemicals are synthesized in a laboratory |
| why is it difficult to distinguish between antibiotics and antimicrobial biotics today | antibiotics are extensively modified in the laboratory (or sometimes synthesized) therefore the distinction between the two are fuzzy |
| what is a -cidal | a type of chemical that kill microorganism |
| penicillin, cephalosporin, and neomycin are (cidals/statics) | penicillin, cephalosporin, and neomycin are CIDALS |
| name the two types of spectrum antibiotics | broad spectrum and narrow spectrum |
| what is a -static | inhibit microorganisms enough for bodies own defenses to take over |
| tetracyclines, erythromycin, and sulfonamides are (cidals/statics) | tetracyclines, erythromycin, and sulfonamides are STATICS |
| what is a broad spectrum antibiotic | effective against a variety of both Gram positive and Gram negative bacteria |
| list five broad spectrum antibiotics | tetracyclines, streptomycin, cephalosporins, ampicillin, and sulfonamides |
| what is narrow spectrum antibiotics | effective against just Gram positive or just Gram negative bacteria |
| name four narrow spectrum medications | penicillin G, erythromycin, clindamycin, and gentamicin |
| ______________________ determines the susceptibility of bacteria | Antibiotic Sensitivity Testing |
| what is the Clinical importance of Antibiotic Sensitivity Testing | measuring the effectiveness of a variety of antibiotics, helps with clinical personnel prescribe the proper treatment |
| describe the Kirby-Bauer (Disc Diffusion Assay) | qualitative test, when a series of antibiotic discs of antibiotic-impregnated discs are placed on incubated plates, looks for zone of inhibition |
| what is a zone of inhibition | depends on sensitivity of bacteria |
| the Epsilometer (E Test) measures | minimally inhibitory concentration (MIC) |
| which test deploys rectangular strip | the E test (Epsilometer) |
| why is the elipsometer called this | the resulting zone of inhibition looks like an elliptical shape |
| the smallest part of the E test intersects with the ______________________________ on the test strip | lowest concentration of the antibiotic |
| Mastering Lab uses the ________________ Agar when performing the Disk-diffusion Assay. This is approved by the National Committee of Clinical Laboratory Standards | Mueller-Hinton Agar |
| (not a question) each bacterium must be tested separately | |
| on a Disc-Diffusion Assay , what should we expect to see on an agar plate after incubation | bacteria should be everywhere except around where the discs |
| how do you measure the effectiveness of an antibiotic on the Disc-Diffusion Assay | measure the zone of inhibition on the agar, record the size of the zones then compare to the clinical + laboratory performance standards |
| what is an abscess | a fight be between bacteria and the organisms immune system and creates a mash of dead cells/tissue and accumulates pus |
| what are some problems with dental abscesses | the infection can spread eventually causing sepsis and death |
| ____________ was the first chemical compound used in patients to treat bacterial infections | penicillin |
| what important event happened in 1941 that changed the course of clinical microbiology | penicillin saved the life of a boy with a fatal sinus infection |
| what is a single-use only instrument | dispose immediately after use to reduce the risk of transmission |
| how are single-use only instruments helpful in clinical environments | helps to eliminate the cost of decontamination processes |
| what is the spaulding classification | used to determine the amount of risk an item's contamination would pose, this includes decontamination processes |
| what are the three (3) categories in the spaulding classification | critical, semicritical, noncritical |
| describe the types of instruments that would be classified as CRITICAL on the spaulding classification | designed to contact sterile tissue (like blood) or enter the vascular system |
| if an instrument with the CRITICAL spaulding classification becomes contaminated | the item MUST be sterilized; otherwise it would introduce an infection to an otherwise healthy patient |
| give some examples of items that would be listed as CRITICAL according to the | forcepts, scalpels, bone saws |
| describe the types of instruments that would be classified as SEMICRITICAL on the spaulding classification | these instruments only make contact with mucous membranes or skin. however, they DO NOT enter wounds, penetrate the skin or other soft tissue |
| if an instrument with the SEMICRITICAL spaulding classification becomes contaminated | it needs to be thoroughly cleaned with a high-level disinfectant (AT MINIMUM). At best steam-sterilized |
| give some examples of items that would be listed as SEMICRITICAL according to the | endoscopes, speculums, dental mirrors, simple hand tools, reusable trays |
| describe the types of instruments that would be classified as NONCRITICAL on the spaulding classification | these items only contact the dry skin and do not come in contact with mucous membranes |
| if an instrument with the NONCRITICAL spaulding classification becomes contaminated | low-level disinfectants can be used to clean |
| give some examples of items that would be listed as NONCRITICAL according to the | stethoscope, Bedpan, walking crutches |
| peracetic acid is a (high/low)-level disinfectant that is used as an alternative to autoclaving for semicritiacl items | peracetic acid is a HIGH level discinfectant |
| how does peracetic acid work | has a low pH which denatures: proteins and cell membranes |
| chlorhexidine is a (high/low)-level disinfectant that can be used as an antiseptic mouth wash and sometimes on hard surfaces | chlorhexidine is a LOW-level disinfectant |
| on the antibiotic test strip for the Elsilometer test, the drug concentration (increases/decreases) from top to bottom | on the antibiotic test strip for the Elsilometer test, the drug concentration DECREASES from top to bottom |
| why is the Epsilometer used in clinical settings. | to the lowest concentration that the drug becomes effective |
| what is MIC | the minimum inhibitory Concentration in the Epsilometer test |
| name some factors that cause vaccine inconsistancy | war, famine, and personal beliefs |
| name some organs in the lymphatic system | lymph nodes, subclavian veins (lymph vessels empty contents here), thyroid glands, spleen Peyer's Patches (small intestine), bone marrow |
| the general idea of your first line of defense for immune system | basic physical and chemical barriers |
| what is the function of a physical barrier | keep things in/out, |
| physical barriers include | skin and mucous membranes of the nose and mouth |
| what are some chemical barriers | pathogen destroying chemicals |
| examples of chemical barriers in the human body are | tears, stomach acid, and ear wax |
| second line of defense for humans include | nonspecific immune system and is triggered by chemicals |
| name the types of chemical signals used in the second line of defense (non-specific immune system) | chemokines, interferons, and complement system |
| what are chemokines and what are their functions | chemicals that trigger an inflammatory response, they recruit macrophages to clear the infection, and results in swelling and pain |
| what are interferons and what are their functions | warn other cells in the body of the incoming infection, in response the surrounding cells will boost their defenses |
| what is the complement immune system and its functions | activation of a signaling system, pathogens become coated in antibodies, |
| what are the three outcomes of the specific complement immune system | phagocytosis, inflammation, attack pathogen membranes |
| what are the steps in the complement system after a pathogen invasion | -pathogen is coated in antibodies - a series of proenzyme zymogens cleave and activate, - produces signalling to recruit more immune cells - pathogens are eliminated |
| name the three pathways for the compliment system | classic pathway, alternative pathway, lectin pathway |
| in the compliment system, the ____________________ pathway is initiated by the antibody binding to the pathogen | CLASSICAL Pathway |
| what happens to C1 in the Classical pathway | can bind to pathogen directly |
| which immunoglobulin is most effective in the classical pathway | IgM |
| what initiates the alternative pathway in the immune system | initiated by the spontaneous cleavage of C3 |
| in the alternative pathway immunoglobulins (are/are not) required | immunoglobulins ARE NOT required for the initiation of the Alternative Pathway |
| the lectin pathway is initiated by | Lectin binding to the sugars in the cell wall and cell membrane |
| all three pathways lead to the cleaving of which protein by which enzyme | cleaving of C3 by the enzyme C3b convertase (produces C3a and C3b) |
| what is the function of C3a | becomes a signaling beacon, attracting more cells to the area (classical pathway) |
| what is the function of C3b | binds to the surface of the pathogen, marking the pathogen for destruction, and the formation of the membrane attack complex |
| what is the 3rd line of defense in the human body | B and T cells (adaptive immunity), specialized memory and specific response |
| what are B Cells | have surface antibody cells , binds to specifically to discint molecular motifs (epitopes) |
| what is an epitope | pathogen's mug shot, it is a binding site for antibodies that triggers an immune cascade |
| what are T cells | cells that recognize and kill infected/malignant body (or somatic "self" cells that no longer bare normal markers, help to activate/stimulate immune cells |
| what is adaptive immunity | an aspect of the human immune system that reacts to defenses that are specific to the pathogen, it only is activated after a first (previous) exposure |
| what is immunological memory | it is a notable characteristic of adaptive immunity (B and T cells) |
| where do T cells mature | thymus |
| where do B cell mature | bone marrow |
| what are the two categories of adaptive immunity | humoral immunity and cell-mediated immunity |
| describe humoral immunity | the production of antibodies and is called such because it discusses the aspect of the immune system that circulated in the lymph and blood stream |
| what is cell-mediated immunity | done specifically by T-Cell responses and does not involve antibodies |
| when is an allergic response triggered | when myelocytes release histamines |
| what other chemicals included in the the allergic response | chemotactic and vasodilators |
| name the three myelocites involved in the allergy response | neutrophils, basophils, mast cells |
| what happens when too much histamine was released | critical drop in BP, heart can fail due to blood loss (remember vasodilation), and inflammatory swelling |
| name the types of mutations that can benefit a microorganism that is invading the human body | - polysaccharide capsule - hemolysin production - antioxidant defense - camouflare with "self" proteins (mimicry) - antivariation - secretion of digestive enzymes |
| what is the polysaccharide capsule | an extracellular covering over a bacterial cell, it covers up the component of the outer membrane/cell wall, lipopolysaccharides (LPS) covered |
| how does hemolytic production help the pathogens invade the body | these are enzymes that breakout of the phagosome after being ingested, they allow bacteria to divide without detection |
| how does antioxidant enzymes help the pathogens invade the body | antioxidant enzymes blocks against reactive oxygen species by immune cells, this allows pathogens to detoxify ROS to Water and Oxygen molecules |
| how does the secretion of degradative enzymes help the survival of a pathogen | degradative proteins destroy antimicrobial peptide defenses |
| what does ELISA stand for | Enzyme Linked ImmunoSorbent Assay |
| what is the ELISA | a tool used for detecting particular molecules |
| what are some practical applications for ELISA | clinical/research applications, detecting antibodies for HIV, and quantifying amount of toxins in river water |
| what are the benefits of ELISA | it is low cost, it has high specificity, and fast results |
| what is the "sandwich" ELISA | when two antibodies used to capture and antibody |
| how does the sandwich ELISA work? | one antibody binds to the small plastic well and the protein. The second antibody then binds to the molecule (this antibody has proteins that react with the solution) |
| what is the capture antibody function in ELISA | the capture antibody functions to captures the molecule of interest and pulls it out of solution and attaches it to the well of the plate |
| what is the detection of the antibody function | attaches to the molecule of interest and has enzymes that can be detected |
| what are some problems with plate counts | it tests for the number of bacteria present. however, it does not allow us to ID the bacteria and it is not direct or specific to the desired bacteria. |
| in ELISA tests, false positives are commonly caused by | insufficient washing after adding a detection body and or improperly pipetting |
| if the blocking solution for ELISA is miss measured, what will happen to the ELISA | there will be no effect on the results |
| if the blocking solution is added after the detention body what will happen to the solution | all the wells would be positive |
| if the blocking solution is added after the detection body why are all the wells positive | the detection body has bound to the well |
| what would the reasons be for indeterminants in ELISA | trace amounts of HIV antibodies found, the failure to watch (does not removes specific antigens/antibodies) and very recent HIV infection |
| what happens to the ELISA if you forget the developing buffer | false negative (the positive control and all patient samples are negative) |
| if an HIV patient has a false negative ... | the patient has not undergone seroconversion, no HIV antibodies |
| what are superbugs | bacteria that are resistant to antibodies |
| what dose MEGA stand for regarding the MEGA plates | Microbial Evolution and Growth Arena |
| what is the MEGA plate theory | bacteria reproduce asexually, but there is genetic change that allows for adaptation, the model of the plate models the evolution of bacteria |
| describe how the plates work in the MEGA plate | the take non-resistant bacteria, the first plate starts with 0 bacteria and as each consecutive increased by antibiotics ten fold up to 1000x |
| what is a DNA mutation | a change in the DNA sequence |
| DNA mutations are ______________: meaning they are random and the effects they have are also random | stochastic |
| DNA mutations (can/cannot) be passed from parent to offspring | DNA mutations CAN be passed from parent to offspring |
| most of the time DNA mutations there (is/is no) change in function | most of the time DNA mutations there IS change in function |
| antibiotic resistance can result from | DNA mutations |
| what does the MEGA plate experiment show | that bacteria evolves and how it adjusts to survive harsh environments |
| name the two types of mutations | induced and spontaneous |
| what are induced mutations | mutations that result from the exposure to chemicals, UV lights, and x-rays |
| what are spontaneous mutations | mutations that result on their own and are not exposed to mutagenic agents |
| mutations are the ultimate source for | new alleles, new genetic variation, epigenetics |
| what are some outcomes of mutations on bacteria | new phenotypes, reduced/increased/no effect on fitness, cause diseases (i.e. cancer) |
| comparing chromosomal DNA and Plasmid DNA, Chromosomal DNA is responsible for | essential genes and required for growth and reproduction |
| comparing chromosomal DNA and Plasmid DNA, Plasmid DNA is responsible for | does NOT contain essential genes, it is easily transfered between bacteria, and can include antibiotic resistance |
| what is a cocktail | a cocktail of antibiotics and deal with resistant DNA |
| what is horizontal gene transfer | more radical mutations, changes the cells genotype at a faster rate, more genetic material can be gained from the transfer |
| what is conjucation | the horizontal gene transfer of a plasmid can cause a bacteria to become resistant to an antibiotic, must be done through physical contact (pili/adhesin) |
| during conjugation Gram-_________________ bacteria mostly form sex pili | Gram-negative form sex pili |
| during conjugation Gram-_________________ bacteria have sticky molecules on the surface that brings the cells together | Gram-positive have sticky molecules |
| what are the steps in conjugation | 1) donor cell comes in contact with recipient, 2) plasma is replicated during the transfer of a single strand, 3) recipient enzymes synthesize a complementary strand, 4) (on occasion) the plasmid with integrate into the chromosome |
| (not a question) through conugation a pathogen is able to gain resistance to gain resistance from other bacterial species by doing so a new strain of bacteria that has accumulated resistance to all the antibiotics in a cocktail | |
| what is transformation | the uptake and integration of extracellular DNA |
| cell-to-cell contact (is/is not) required for transformation | cell-to-cell contact IS required for transformation |
| what is needed for a cell to undergo transformation | 1) cell needs to be competent, 2) DNA should exist outside the cell, 3) after DNA intake, the cell should incorporate the DNA into the chromosome |
| GMO's insert a gene of interest into a cell using a to create recombinant cell uses the which gene transfer technique | transformation |
| what is competent | a cell MUST be competent to undergo transformation; otherwise, free-floating DNA release |
| what are the six steps to transformation | 1) binding, 2) fragmentation, 3) transport, 4) uptake, 5) lysis, and 6) integrateion |
| what is transposable | changing a chromosome to a plasmid |
| what is transduction | occurs with viruses, this is when bacterial chromosomal DNA enters into a virion and is injected into another bacteria |
| infections disease is caused by _______________; which includes... | parasitic organisms; bacteria, viruses, parasites, and fungi |
| how are infections diseases passed from individuals | directly and indirectly |
| genetic diseases are caused by | mutations |
| deficiency diseases are caused by | deficiency in nutrients |
| physiological diseases | change in organ function (this is not contageous) |
| infections is caused by ________ | an infectious agent |
| what is colonization | infectious agent enters the body and multiplies |
| what are the characteristics of infections diseases | fever, redness, and swelling at the site of an infection |
| the severity of the infectious disease depends on | multiple factors, virulence of pathogen, site of infection, and host defenses |
| differential media uses characteristics | metabolic and biochemical characteristics which lead to changes in colony morphology or medium |
| staining is used to | enhanse contrast of biological samples |
| because of staining, we can see | bacterial size, shape, arrangement, and cell structures |
| bacterial metabolic processes are driven by __________ and a variety widely across bacterial species | enzymes |
| common differential stains include | gram stains, acid fast, and endospores |
| gram staining is the most widely used which detects | a cell wall (gram-positive = presence of a cell wall) |
| the presence of a cell wall and gram-positive staining results show us what | thick peptidoglycan presence, binds to crystal violet, a positive test appears purple |
| the presence of a cell wall and gram-negative staining results show us what | thin layer of peptidoglycan, usually pink (from the safranin) |
| what is the 1st step din identification process of microbial identification | gram staining |
| antibiotics that target peptidoglycan would be less effective on bacteria that are gram-(negative/positive) | antibiotics that target peptidoglycan would be less effective on bacteria that are gram-NEGATIVE |
| acid fast bacteria are best for | bacteria that are not clearly seen in the gram-positive and gram-negative |
| acid fast bacteria contains | mycolic acid |
| the red stain in the acid fast bacteria is | carbol fuschin (red stain) |
| in acid fast, cells with mycolic acid present as ______________ and bacteria with out mycolic acid present as _______________ | red; blue |
| what main family of bacteria are specifically known to have mycolic acid | Mycobacteria |
| why is the acid-fast staining important in a clinical setting | it helps to identify Mycobacteria which are the cause of many diseases such as tuberculosis and leprosy |
| endospore stain is specifically for | dormant bacteria |
| when do endospores form | when the environments are less favorable (like high/low temps, radiation, chemical disinfectants) |
| what stain is used for the endospore stain | Schaeffer-Fulton stain |
| what is the main ingredient in the schaeffer-fulton stain | malachite green |
| what do biochemical tests identify | metabolic properties |
| biochemical tests are designed to identify | common pathogens |
| what are the draw backs to the biochemical tests ? what are these draw backs are | they are only used for organisms in the laboratory. nucleic acid-base |
| what are some examples of biochemical tests | catalase tests, oxidase tests, urease tests, and indole tests |
| what does the catalase test test for | the presence of the catalase enzyme, converting hydrogen peroxide to water and oxygen, it helps protect the cell and is present in aerobic bacteria |
| what are the types of cultures that help identify microorganisms | nutritive, enrichment, differential, selective |
| the general purpose medium agar that is great for laboratory | nutritive agar |
| this agar can grow most bacteria with no particular preference to species of advantages | nutritive agar can grow most bacteria |
| what is selective media agar | an agar that has inhibitory agents that allow growth of some colonies and not others |
| blood agar is both __________________ and ___________________ (hemolysis) | nutritive; differential |
| what is enrichment media agar | specific nutrients selectively supports growth of some |
| (not a question) one medium can fall into several categories | |
| (not a question) the colony morphology and motility | |
| what is differential media agar | agar contains a chemical that can change the appearance of some colonies and not others |
| the MacConkey's agar is selective for _________________ and differential for ___________________ | Gram-negative; lactose fermentation |
| biochemical tests uses variation in _________________________ and ________________________ | metabolic processes and enzymatic activity |
| what is the urease test | catalyses of urea into ammonia, water, and Carbon Dioxide. |
| what is in the urease medium for the urease test | adds urea to the test |
| how does the urease detect ammonia | pH, ammonia increases the pH of the medium |
| how is the presence of catalase detected | the bacteria produces bubbles when submurged into hydrogen peroxide |
| if a urease is negative for catalase test | there are no bubbles in the hydrogen peroxide |
| the indole test, tests for | the presence of indole |
| indole is produced from | p-dimethyl-aminocinno-maldehyde |
| a positive indole test is ______________________ and a negative indole test is _____________________ | pink; colorless |
| Cytochrom C oxidase is part of what major ATP creator in the cell | electron transport chain |
| the oxidase test, tests | the presence of cytochrome C oxidase |
| oxidase positive | blue |
| oxidase negative | colorless |
| what is the goal of antibiotic combination therapy | this reduces the resistance of the antibiotic resistance |
| what are the benefits of antibiotic combination therapy | allows clinical practitioners to use lower doses of antibiotics and enhances bacterial activity |
| how do you determine the effect of additive effects of antibiotics | both discs are placed on a lawn of cells on an agar plate |
| if there is a uniform zone of inhibition , what is the effect of the two medications | additive |
| if the zones of inhibition merge in the middle, what is the effective of the two medications | synergic |
| what is an additive effect | the overall effect of the two antibiotics is no greater than the overall sum of the two individuals |
| what is synergism | the overall effect of each antibiotic is greater than the sum of the two individual antibiotics |
| (not a question) in synergism, each antibiotic has a synergistic effect on the other | |
| what major class of bacteria is identified by the catalyes test | Staphylococcus |
| the catalase is absent in which two major classes of bacteria | Streptococcus and enterococcus |
| streptococcus and enterococcus produce what enzymes instead of catalase | superoxide dismutast and perocidae |
| what is catalase | an enzyme that converts hydrogen peroxide to water and oxygen |
| briefly descrive the features of streptococcus | gram-positive cocci, the same family as Enterococcus |
| what are the subgroups of Streptococcus based on | Lancefield Classification |
| the Lancefield classification is based on | similar surface antigens |
| list the groups of Streptococcus in the Lancefield Classification | A,B,C,D,K, Viridans, Pneumoncocci |
| species in the Lancefield classification A | Streptococcus pyogens |
| Streptococcus pyogenes is responsible for what human diseases | pharyngitis, scarlet fever, impetigo, (invasive infections that can lead to toxic shock) necrotizing fascitis, immune complications (rheumatic fever) |
| species in the Lancefield classification B | Streptococcus agalactiae |
| Streptococcus agalactiae is responsible for what human diseases | Neonatal meningitis, pnenomia, UTI, bacteremia, puerperal fever, vaginitis |
| species in the Lancefield classification C | Streptococcus equi |
| Streptococcus equi is responsible for what human diseases | it rarely causes pathogens in humans, but is pathogenic to animals and cause equine strangles |
| species in the Lancefield classification D | Enterococcus faeculis and Strepococcus bovis |
| Enterococcus faeculis and Streptococcus bovis is responsible for what human diseases | UTI's, and Biliary tract infections |
| species in the Lancefield classification K | Streptococcus salivarius |
| Streptococcus salivarius is responsible for what human diseases | cavities and endocarditis |
| species in the Lancefield classification pneumococci | Streptococcus pneumoniae |
| Streptococcus pneumoniae is responsible for what human diseases | meningitis, pneumonia, bacteremia |
| species in the Lancefield classification viridans | Streptococcus mutans/Streptococcus mitis |
| Streptococcus mutans/Streptococcus mitis is responsible for what human diseases | dental caries and endocarditis |
| what are capnofiles | bacteria that grows best in carbon dioxide |
| name a class of bacteria that are capnofiles | streptococcus |
| what are some distinguishing characteristics of the Streptococcus family | colony morphology, hemolytic properties, and biochemical reactions |
| describe the type of hemolysins that are produced by Streptococcus | they hydrolyze red blood cells |
| what types of hydrolytic patterns to streptococci express on blood agar | alpha, beta, and gamma |
| streptococcus is specifically susceptible to which antibiotics | bacitracin and SXT |
| describe some of the growth patterns of streptococci bacteria | susceptible to bacitracin and SXT, halotolerant, hydrolyses exculin (bile) |
| Streptococcus on Mannitol | the only members of this family that grow on mannitol are Enterobacteria |
| describe the beta hemolytic patterns | complete clearing of the blood around the colonies |
| describe the alpha hemolytic patterns | partial lyses, greenish-grey coloring |
| describe the gamma hemolytic patterns | no change in medium |
| describe the Esclin (Bile) agar | contains bile salts, escullin, ferrich ammonium citrate, beef, and gelatin extracts |
| esculin agar is selective for | enteric organismes |
| esculin (bile) agar is differential for | the ability of a bacteria to distinguish microorganisms that can hydrolyze the carbohydrate esculin |
| what is the differential ingredient in the bile agar | esculin and ferric ammonium citrate |
| if the microorganism tests positive for the esculin hydrolsis | 50% of the agar forms black parcipitate |
| Staphylococcus is Gram- _________________ | Staphylococcus is Gram-POSITIVE |
| what are the two major species of Staphylococcus | S. aureus and non-S. aureus |
| What does MRSA stand for | Methicillin-Resistant Staphylococcus Aureus |
| what does MRSA stand for | Methicillin Resistant S. Aureus |
| MRSA is a subtype of | Staphylococcus aureus |
| MRSA arose in the 1960's and became a problem because | it is resistant to methicillin and other antibiotics |
| name two properties of Staphylococcus that can help identify this class | 1) ability to grow in a high salt concentration, 2) the production of catalase |
| Staphylococcus aureus is responsible for what human diseases | STI (Skin + Soft Tissue Infections), toxic shock syndrome, pneumonia, meningitis, arthritis, and osteomyelitis |
| Staphylococcus epidermidis is responsible for what human diseases | mostly opportunistic infections, also a normal resident on human skin, this is the most clinically significant non S. aureus |
| how can S. aureus be distinguished from non S. aureus | mannitol fermentation and positive coagulase tests |
| characteristics of Staphylococcus are | gram-positive, catalase positive, halotolerant |
| DNase test is (differential/selective/both) | DNase test is DIFFERENTIAL ONLY |
| the DNase test contains | an emulson of DNA, peptides, and methyl green |
| the pH of the DNase is | 7.5 |
| a clearing around the colonies on a DNase test | hydrolysis of DNA and the presence of DNase |
| what is the mueller hinton test | antimicrobial testing, tests susceptibiity to antibiotic novobiocin |
| name the two main columns used to identify unknown bacteria | observation and interpretation columns |
| what is the observation column for | what you actually observe |
| what is the interpretation column | the the positive/negative test actually means |
| what is an identification matrix | a table that helps with the identification of bacteria. it allows you to compare your results to known identification test results |
| (not a question) when testing bacteria, the more tests you can do on the bacteria, the more accurate your results | |
| describe some characteristics of gram-negative bacteria | a thin layer of peptidoglycan with an outer phospholipid bilayer (lipopolysaccharides (LPS) |
| the larges group of human pathogens are gram- ___________________ | the larges group of human pathogens are gram-NEGATIVE |
| what is the main lipopolysaccaride that can cause morbidity and mortality to humans in gram-negative bacteria | Lipid A |
| Lipid A is an (endo/exo)toxin | Lipid A is an ENDOtoxin |
| what are the three sugars in the TSI (Triple-Sugar Iron) test | glucose, sucrose, and lactose |
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