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Microbio Lab Prac 2
| Question | Answer |
|---|---|
| Give 2 reasons why its important to use controls when you're doing clinical testing | controls are used to monitor the validity of the results. If the reactions of the controls are not as expected the tst results are invalid and cannot be reported. Controls are what the reaction should look like |
| Antitoxin | contains antibodies that will neutralize exotoxins |
| Antiserum | is a preparation of antibodies |
| Adjuvant | is a chemical included with vaccines to enhance an immune response |
| Monoclonal antibody | is produced by a hybridoma cell, which is a plasma cell fused with a myeloma cell |
| Interpret the data of titres One patient: Day 1= 160 Day 7=160 Day 14=160 Second Patient: Day 1= 0 Day 7= 0 Day 14= 0 Third patient: Day 1= 80 Day 2= 160 Day 14= 1280 | Patient 1= had mononucleosis in the past or at least was sensitized to Epstein Barr virus Patient 2= has never had an immune response to the virus Patient 3= currently has the disease of mono |
| Natural killer cells are considered part of your nonspecific immune response wile the production of Tc killer cells is considered a specific response. Explain | NK cells are nonspecfic immune defense cells. They survey cells looking for those lacking MHC-1 receptor sites. Th cells (t helper cells) via interleukin-2 direct Tc cells to bind to cells lacking MCH-1 receptors and lyse it using perforins/granzymes |
| When diagnosing a disease like hepatitis A, labs often take an acute blood sample and a convalescent sample from the patient and look for a 4-fold rise in the titre. Why? | An acute sample is done early in the disease. A convalescent sample is done when one is recovering. If teh acute sample has a titre of 40, the convalescent sample would have to be 160 to show disease process has occured |
| In the disinfectant test; identify one experimental variable and one control variable | EV: various disinfectants CV: same organisms tested against varying chemicals and timeline was the same |
| Antiseptic | a chemical that kills most pathogenic organisms on living tissues (in humans) |
| Disinfectant | chemicals kill most pathogens on fomites, they are not to be used on living tissues |
| Fungicidal | chemicals kill fungi (molds and yeasts) |
| Penicillinase (beta lactamase) | an enzyme produced by penicillin rsistant strains of bacteria to inactivate penicillin into a harmless chemical (penicilloid) |
| Give similarities between the agar diffusion (Kirby Bauer) and the tube dilution sensitivity tests | Both tests organisms for antimicrobial susceptibility, standarized tests, determines the specific antimicrobial that is most effective in treating that particular strain of bacterium |
| Give differences between the agar diffusion (Kirby Bauer) and the tube dilution sensitivity tests | KB uses a Mueller-Hinton agar, MIC uses a dilution tray containg a supporting medium. MIC provides the minimum dilution of an antibiotic that would be effective in treating a specfic bacterial infection, KB does not |
| Indicated 4 things that must be standardized in the Kibry Bauer sensitivity test and why is standardization necessary? | 1. Mueller-Hinton agar poured at 4mm thickness 2. Standardized antibiotic disks are used 3. standarized inoculum used 4. incubate plates for 18-24 hors at 37 C and it allows for reproducible results |
| Ciliated epithelium | moves mucus with trapped organisms and debris out of the resp tract |
| normal flora | colonizes areas of the body to prevent or decrease access to the area by a pathogen |
| Alverolar macrophages | phagocytize debris and organisms that reach alveoli this is a protective response |
| Secretory IgA | is found in body secretions near the surface; it binds to microorganisms and prevents them from attaching and invading mucous membranes |
| List 5 organisms that make up the normal flora of the Upper resp tract | 1. Neisseria sp. 2. Corynebacterium sp. 3. Streptococcus sp. 4. Staphylococcus sp. 5.Bacteroides sp. 6. Candida albicans |
| ID the etiologic agent of pneumococcal pneumonia. Give the gram reaction and list 2 virulence factors for this microorganism | 1. Streptococcus pneumoniae 2. Gram pos diplococci 3. Capsule, streptokinase, hemolysin |
| An example of a gel precipitation reaction is shown where there is only one line and its between the middle circle and the pig ag. What type of antigen is involved? | Soluble antigen is involved. The pig antigen and unknown antibody diffuse toward each other in the agarose until a zone of equilibrium is achieved. A lattice forms between the soluble antigen and antibody capable of binding to this antigen. |
| The following agglutination reaction occurred between an unknown bacterium and anti-Escherichia coli 0157:H7 (on the left). What can be said of the unknown organism? | The unknown organism is Escherichia coli 0157:H7. Agglutination reactions involve particulate antigens and they agglutinate with a specific antibody forming cross-linking between antibodies and antigens attached to cells |
| If a patient has a Hepatitis B antibody titre of 640 what does this mean? | The patient has developed antibodies to Hepatitis B virus through immunization or natural exposure to the virus. The patient has seroconverted (produced antibodies). |
| Antigen | a chemical substance (usually a protein) that elicits an immune response. Antigens are usually proteins, but substances such as glycoproteins, lipoproteins, or large complex carbohydrates may be antigenic). |
| Antigenic determinant (epitope) | the portion of the antigen that stimulates an immune response. |
| . Antibody | is a defensive protein produced in response to antigenic stimulation. It is capable of binding to the epitope of the antigen it was produced against. Once the antibody and antigen bind to each other, other defensive processes are activated. |
| Name a species that produces: a. Alpha hemolysin | Streptococcus pneumoniae |
| name a species that produces beta hemolysin | Streptococcus pyogenes |
| name a species that produces gamma hemolysin | Staphylococcus epidermidis |
| Staphylococcus aureus gram reaction | gram pos staphylococci |
| streoptoccus agalactiae | gram pos cocci, strepto |
| E coli | gram neg bacilli |
| Pseudomonas sp. | gram neg bacilli |
| streptococcus pyogenes | gram pos streptococci |
| bacillus sp. | gram pos bacilli |
| klebsiella pneumoniae | gram neg bacilli |
| clostridum sp. | gram pos bacilli, sporeformer |
| proteus sp. | gram neg bacilli |
| salmonella sp. | gram neg bacilli |
| staphylococcus epidermis | gram pos staphylococci |
| shigella sp. | gram neg bacilli |
| streptococcus pneumoniae | gram pos diplococci |
| Compare and contrast agglutination and precipitation. similarities | - both involve antigens and antibodies. - both involve epitopes binding to antibodies. - both identify an unknown if either the antigen or antibody is known. |
| Compare and contrast agglutination and precipitation. differences | A involves particulate antigens; precipitation involves soluble antigens .Agglutination involves physical mixing to bring antigen and antibody closer together; ppt involves diffusion. |
| Name a chemical that is bactericidal against Bacillus sp. | cidex |
| Compare and contrast a Gram positive bacterial cell wall from a Gram negative bacterial cell wall. gram pos | Gram positive bacterial cell wall: 60-90% of the cell wall is peptidoglycan, teichoic acid is also present linking the peptidoglycan molecules together. |
| Compare and contrast a Gram positive bacterial cell wall from a Gram negative bacterial cell wall. gram neg | Has a periplasmic space next to the cell membrane; going toward the outside of the cell peptidoglycan; attached to the outer layer of this is the outer membrane. inner layer of the outer membrane is made up of proteins and phospholipids. |
| Diagram a flow chart, starting with Gram reaction and hemolytic pattern, that would allow identification of Streptococcus pyogenes (Grp. A strep: GAS) from Streptococcus agalactiae (Grp. B strep). | gram pos streptococci, cocci to > GAS antigen test and bacitracin sensitivity than if its positive its GAS than if its negative its GBS |
| Tuberculosis | EA: Mycobacterium tuberculosis Acid fast stain Acid fast positive due to high mycolic acid content in cell wall; agent of tuberculosis. |
| Strep throat | EA: Streptococcus pyogenes (Group A strep; GAS) Gram stain: Gram positive streptococci Agent: bacitracin sensitive; quick antigen test; sequelae: Scarlet fever, glomerulonephrities, and rheumatic fever…; tx: penicillin, cephalosporin, erythromycin |
| Pneumococcal pneumonia | EA: Streptococcus pneumoniae Gram stain: Gram positive diplococci Cause of pneumococcal pneumonia; resistant strains; tx: vancomycin…; prevention: vaccine and decrease high risk behaviors. |
| Scarlet fever | EA: Streptococcus pyogenes Rash on body clear around mouth deeper rash on cheeks, axillary and inguinal regions; caused by GAS infection such as strep throat or a skin infection;tongue may have a strawberry appearance; skin areas with a rash may peel |
| Diptheria | EA: Corynebacerium diptheriae Gram stain: Gram positive bacilli with pleomorphism (multiple shapes) Acute URT disease; highly infectious. |
| H. influenzae meningitis | EA: Haemophilus influenzae, type b Gram stain: Gram negative bacilli Causes meningitis in infants, young children, and the immunocompromised. |
| Gonorrhea | EA: Neisseria gonorrheae Gram stain: Gram negative diplococci; in a clinical specimen from a patient, look for intracellular GNDC in neutrophils (diagnostic from male urethral discharge). See table in Lab 13 for other required information. |
| Syphilis | EA: Treponema pallidum Don’t gram stain, use Dark field microscopy to view spirochete; serology testing; and Fluorescent microscopy. Person to person contact; Use lab 13 material to describe primary, secondary, tertiary, and congenital syphilis. |
| Cystitis | Infection of the bladder that is commonly caused by Escherichia coli. Gram stain of E. coli is Gram negative bacilli |
| STD: Chlamydia | EA: Chlamydia trachomatis gram negative |
| Infectious mononucleosis (IM) | Epstein-Barr virus |
| Tetanus | Clostridium tetani Gram stain: Gram positive bacilli Strict anaerobe; spore former. |
| Psittacosis | EA: Chlamydia psittaci Diagnosis by serological methods (antigen and antibody testing). Small bacterium; obligate intracellular parasite; treat with tetracycline; organism is obtained from inhaling contaminated dust/bird feces |
| Primary atypical pneumonia | EA: Mycoplasma pneumoniae no Gram stained because the organism lacks a cell wall. passed from human to human; inhaled from contaminated respiratory droplets; causes a bacterial pneumonia that presents atypical pneumonia; use antigen/antibody test |
| Klebsiella pneumonia | EA: Klebsiella pneumoniae Gram stain: Gram negative bacilli URT flora for some; capsule; caused by impaired pulmonary functions; increased risk for those that have increased alcohol intake, malnutrition nosocomial infection; tx: cephalosporins |
| With reference to fluid or gel precipitation reactions, explain zone of equivalence | As antigens and antibodies diffuse toward each other they reach an action zone. This zone is where they are changed into a lattice (soluble antigens bind to antibodies). |
| List the five classes of antibodies. | IgA, IgM, IgG, IgD, IgE |
| SS agar | |
| hektoen enteric agar | Selective: Shigella, Salmonella, E. coli Higher bile and dyes ; noGP and many GN. Differential lactose, sucrose, salicin and pH indicator Ferm appear yellow, orange, salmon or pink Non-fermenters appear green/blue. Contains sulfates + iron black |
| MAC agar | Selective: Low bile & crystal violet dye inhibits GPs for growing many GNs Differential: Contains lactose: Lactose fermenters pink colonies Non-fermenters colorless or beige colonies |
| mueller hinton agar | Grows most non-fastidious bacteria Used from susceptibility testing in the Kirby-Bauer test. Agar plates are poured 4mm in depth. Medium has a neutral pH. |
| thayer martin agar | Chocalate agar (enriched medium; Sheep blood cells that have been lysed and oxidized) plus antibiotics. Antibiotics inhibit all organisms except to Neisseria species (fastidious organism). |
| explain how soap works | it is a wetting agent that makes the microbes slip off |
| explain how cationic detergents work | The purpose is to neutralize the static electrical charges from residual anionic (negative ions) detergent molecules. Since the negative charges repel each other, the positive cationic detergent neutralizes this charge. |
| name an antiseptic | Hydrogen peroxide, betadine, alcohol |
| Of the lab strains (you tested), Staphylococcus aureus and Psuedomonas sp., which is more resistant to numerous antimicrobial agents? | Psuedomonas sp. |
| Define what resistant means with reference to the Kirby-Bauer susceptibility test. | The organism is resistant and will grow in the presence of the drug being tested in the patient. the organism is either growing right up to the drug disc or within the range stated on the chart for interpretation of Kirby-Bauer tests. |
| Define what susceptible means with reference to the Kirby-Bauer susceptibility test. | The organism is susceptible and will be inhibited from growing by the drug being tested in the patient. Which means that the organism is not growing up to the disc on the Mueller-Hinton agar plate (use chart to interpret). |
| what role does secretory igA play in protecting the URT | covering mucosal surfaces, which is the major contributor to pathogen-specific immune responses to protect the host from infection |
| what is a coliform | Coliform bacteria are defined as Rod shaped Gram-negative non-spore forming and motile or non-motile bacteria which can ferment lactose with the production of acid and gas when incubated at 35–37°C |
| why should infants and toddlers be kept away from iguanas | iguanas carry Salmonella in their intestinal tracts |
| patient suspected of having cystitis caused by E. coli cultivated from their urine. The colony count is 75,000 cells/ml of urine. This is the first time this patient is suspected of having cystitis. What does this information mean to the clinician? | The patient has a subthreshold infection. Which means it does not meet >100,000 organisms per ml of urine needed to indicate a urinary tract infection (UTI). |
| What is the usual mode of transmission for gonococcal ophthalmia in newborns? What is the etiologic agent? What is the recommended therapy? | EA: Neisseria gonorrheae Transmitted by vaginal delivery whereby the newborn picks up the pathogen from maternal vaginal flora. TX: erythromycin eye drops. |
| What syphilitic stage presents with a rash on the palms and soles? | Secondary syphilis |
| name a disinfectant | Lysol, cidex/cidecon |
| What are capnophiles? | microorganisms that thrive in the presence of high concentrations of carbon dioxide |
| Which organisms are STORCH agents? | Syphilis, Toxoplasmosis, Rubella, Chlamydia, Herpes |
| Which of the following cells or structures are examples of where antigens may be found; or the molecule may act as an antigen? | a. Microbial cells and viruses b. Proteins and polysaccarides c. Cell membranes and bacterial capsules |
| IgG | most abundant in serum |
| IgA | Second most abundant in serum |
| IgM | Third most abundant in serum. |
| IgD | Fourth most abundant in serum |
| IgE | Fifth most abundant in serum |
| What is added into MacConkey agar to inhibit gram positive and fastidious gram negative bacteria? | bile salts and crystal violet |
| Particulate antigens are used in which test: | aggultination |
| Starting at the core of an endospore the protective layers from the inside out are | cortex, spore coat, and exosporium coat |
| Disinfection is a cleansing process that destroys vegetative pathogens and endospores | false |
| Is it correct to state that dish washing sterilizes one's dishes? | No. It should be referred to as a sanitizing process only |
| which of the following is safe to use on or near living tissue? | antiseptic |
| Identify the bacterial survival structure that are colored green in the picture. These structures do not stain in the Gram stain, but will stain with a special staining technique. little circles inside a bacilli | bacterial endospore |
| The Kirby-Bauer method determines susceptibility of organisms to antimicrobial agents. The results are compared to a standardized range for each drug and the organism is susceptible, resistant, or intermediate to a particular drug concentration. | true |
| When attempting to sterilize bacterial endospores using an autoclave, the temperature must reach 100C at 3 psi for 5 minutes. | false; The temperature must reach 121C at 15 psi for 15-20 minutes to effectively destroy both bacterial spores and endospores |
| Autoclaving uses steam heat as its sterilizing agent. Of the following, choose which method of controlling microbes this fits. | physical |
| UV radiation is usually considered a disinfectant rather than a sterilizer. UV radiation is 99% effective in decreasing concentration of airborne microbes. | true |
| A fungicidal agent has what effects? | destroys fungal spores, hyphae, and yeast growth |
| All gram negative bacteria have an outer layer of the outer membrane that consists of: | lipopolysaccharides, Lipid A, and porin proteins |
| Soaps are strong microbicides. | false |
| In order to identify a Streptococcus speices, exhibiting a beta hemolytic pattern around colonies on a sheep blood agar plate, which test would you perform? | Strep A quick antigen testand bacitracin susceptibility if needed. |
| Which of the following would be most easily killed using heat? | Gram negative, non-spore forming bacteria |
| Organisms that grow best at increased carbon dioxide concentrations are called | Capnophiles |
| Of the following genera, which can be found as part of the microbiome (normal flora or indigenous flora) in the oropharynx of healthy individuals? | a. Streptococcus sp. b. Staphylococcus sp. c. Neisseria sp |
| An environment that provides increased carbon dioxide and low oxygen is | a candle jar |
| What are some of the benefit(s) of normal microbiota of the intestines? | a. Synthesize and secrete vitamins b. Prevent colonization by pathogens c. Stimulate production of antibodies |
| A bacterium producing black colonies on HE agar are producing ______________. | Hydrogen sulfide |
| What is the most likely gram reaction of the organism growing on Hektoen-Enteric agar? | gram neg |
| The bacteria are species of Salmonella, Escherichia, Klebsiella, Proteus, Serratia, and Proteus. What is the oxygen requirements of this group of bacteria? | Facultative anaerobes |
| What common component is added to MacConkey agar and Hektoen-Enteric agar to inhibit fastidious gram negative bacteria? | bile |
| The environment created in a candle jar, which was used to enhance the growth of Streptococcus sp., contains what? | Increased carbon dioxide and decreased oxygen |
| Agglutination involves _______ antigens. | Particulate |
| Which of the following would NOT be considered an enteric? | Staphylococcus aureus |
| The bacterium below is growing on HE agar. Some other characteristics of this bacterium include: Non-fastidious Gram negative bacilli Facultative anaerobe Member of the Taxonomic order Enterobacterales Is involved in food and waterborne diseases | Salmonella sp. |
| Gram positive bacilli with endospores present Strict anaerobe Exists in a spore state in soil Germinates in necrotic tissue releasing toxins that damage human tissue Involved in numerous diseases such as gas gangrene, tetanus, botulism | Clostridium sp. |
| What do acid fast bacilli, shown in the picture, have in their cell walls that make them resistant to traditional gram staining techniques? | Mycolic acid |
| Which of the following tests differentiates Staphylococcus aureus (positive) from other Staphylococcus sp. (negative)? | Coagulase test and mannitol fermentation |
| What is the etiological agent of Syphilis? | Treponema pallidum |
| When separating Staphylococcus species from Streptococcus species there are a number of tests that can help you. Of the following, which is only true of Streptococcus species? | Catalase test negative |
| Given the following information, choose the best fit. Gram negative bacilli Facultative anaerobe Reservoir is the intestinal tract of animals Oxidase negative Ferments lactose Most common cause of cystitis | Escherichia coli |
| The stage of syphilis that is characterized by a rash, allopecia, and lesions in the mouth is? | Secondary |
| Gram pos streptoc Catalse neg Group A antigen test pos Small white colonies a beta-hemolytic pattern on SBA diseases: pharyngitis, scarlet fever, skin diseases Sequelae glomerulonephritis and rhematic fever which may lead to rheumatic heart disease | Streptococcus pyogenes |
| If a microbe only grows near the surface, | it is an obligate aerobe |
| If a microbe grows only deep into the broth it is an | obligate anaerobe |
| If a microbe grows throughout the broth it is | a facultative anaerobe. |
| gram reaction for gohnorra | neutrophils some containing many Gram negative diplococcus |
| Primary Syphilis gram reactionn | spirochetes of Treponema pallidum |
Created by:
alexs13