70 terms

Microbiology Exam 4

What are some specimens that are used to isolate pathogens?
Feces, urine, mucosal swabs, blood, biopsy tissue, cerebrospinal fluid, pus, sputum (something that you can give a Dr.'s office that comes from the body.)
What is the basic protocol to isolate a pathogen using classical techniques?
grow, isolate, and identify
What does it mean when a physician orders a culture and sensitivity?
When you culture a bacteria, you are making it grow. In order to test sensitivity, you use the antibiotic disk to see if that particular bacteria is resistant to it or sensitive, which will have a bigger zone of inhibition.
What type of media are blood agar, MSA, and EMB? What are used to isolate and identify?
Blood Agar are general purpose media, and they support growth of most aerobic and facultatively aerobic organisms. EMB and MSA are selective media, which allows some organisms to grow while inhibiting others. EMB is selective for gram negative rods because it has crystal violet and bile salts in it. It is also differential because it contains lactose. Lactose fermenters are red and the non fermenters are colorless. It is used to isolate enteric pathogens like E. coli and Salmonella. MSA is used to isolate staph.
What is the difference between bacteremia and septicemia?
bacteremia is the presence of bacteria in the blood, and it is uncommon in healthy individuals. septicemia is blood infection; growth of bacteria.
What are the advantages of doing a urine dipstick test?
Non invasive, easy, fast, and cheap
What type of specimen is needed for a urine culture? What should you do with a urine sample if you can't get it to the lab right away?
The specimen for a urine culture is a clean catch midstream urine sample. If you can't get it to the lab right away then you would need to put it in the refrigerator to keep the bacteria that may be in it from growing.
What organism gives a green metallic scheen on EMB and why does this happen?
E. coli b/c it is definitive for the lactose fermintors.
If you did a gram stain on someone with bacterial meningitis what would you expect to see and what type of media does this organism grow on?
(Not Sure) It appears as a gram negative diplococci, and in order to grow it streak a chocolate agar plate.
What is an anaerobic jar used for and what makes it anaerobic?
It is used to exclude oxygen contamination because oxygen is toxic to obligate anaerobic organisms. The catalyst and hydrogen generator packet produce and maintain anoxic environment.
What are differential tests used for? What are some examples of differential tests?
to measure the presence or absence of enzymes involved in catabolism of specific substrates. Ex: sugar fermentation. (Refer to table 32.3)
What type of reactions could you possibly see in a glucose phenol red broth?
red with growth (turbidity): could not use the sugar
yellow with growth (turbidity): fermented sugar,pH went down
pink with growth: used peptones instead of sugar; pH went up
gas in Durham tube = gas production If the organism can ferment the sugar (glucose), it will produce acid (yellow color) and/or gas (space in the durham tube). red: neutral; yellow: acidic; pink: basic
What are possible reactions in a TSI tube?
n the TSI tube red/yellow means glucose fermentation, yellow/yellow means lactose or sucrose fermentation, gas is breaks in the agar and black ppt means hydrogen sulfide production
What does the citrate test check for?
Citrate test is to see if an organism can use citrate as a sole carbon source. Normally they use glucose but this media does not have glucose and has citrate. It is positive if it turns blue.
What is the advantage of a multi-test like the APE-20E?
The API-20E is a multi-test used to identify Gram negative bacteria. The advantage is that it takes up less space and is cheaper.
What is the purpose of doing a disk diffusion test like the Kirby Bauer test and what does a zone inhibition mean?
A disk diffusion test is the standard procedure for assessing antimicrobial activity. The Kirby Bauer test is used to determine antibiotic sensitivity. A zone of inhibition is used to determine an organisms susceptibility to an antimicrobial agent. The bigger the zone the bigger the killer.
What does MIC determine? What does it mean?
Minimum inhibitory concentration is a procesure used to assess antibiotic susceptibility with regard to various concentrations.
What is the purpose of biosafety levels and what's the difference b/w I and IV?
biosafety level: to classify laboratories according to their containment potential. BL I = student lab/BL 4 = high safety lab
What is fever a symptom of? What does your body do to fight an infection? Why does it take a couple of weeks to recover from an infection without medication?
fever is symptom of infection, body uses antibody to fight an infection, and it takes a couple of weeks b/c it takes a while for your body to build antibody titer
How are polyclonal antibodies different from monoclonal antibodies? How are monoclonal antibodies made? What type of diagnostic test are monoclonal antibodies used for?
(Not sure on first part)Polyclonal antibodies are antibodies made by many different B cell clones. Polyclonal antiseria provide adequate immune protection to the host but at not precisely reproducible. Monoclonal Antibody: Antibody made by a single B cell clone; produced in vitro. for monoclonal it's clinical diagnostic test, immunological typing of bacteria, and ID of cells containing foreign surface antigen (ex. a virus infected cell); they can also detect and treat human cancers; examples are pregnancy and drug tests
What is serology? What do you find in a serum?
Serology is the study of antigen-antibody reactions in vitro. Serum is blood plasma without clotting factors.
What is a neutralization reaction? Give an example.
The interaction of antibody with antigen to block or distort the antigen sufficiently to reduce or eliminate its biological activity. Example: Neutralization of a microbial toxin by specific antibody
How is a precipitation reaction different from an agglutination reaction? Give examples of each.
precipitation has soluble antigens, and agglutination has insoluble antigens. It is insoluble b/c it is on the red blood cells. An example of precipitation would be a quantitive measure of antibody concentration. Agglutination is seen when you do blood typing.
What is fluorescent antibody and what would you use it for?
A fluorescent antibody is an antibody with a fluorescent label.use fluorescent dye to identify things like bacteria that doesn't grow in culture like syphilus, diagnose malignant cells, separate mixtures of cells into relatively pure populations, define the #s of individual cell types in complex mixtures ( blood).
Explain the basic principle of an ELISA and how is a direct ELISA different from an indirect ELISA?
ELISA: employs covalently bonded enzymes to label antibody molecules. Direct is the detection of antigen, and indirect is the detection of antibody.
What is the basis of an RIA?
(Not sure) Employs radioisotopes as antibody or antigen conjugates instead of enzymes. Isotope iodine -125 is commonly used as the conjugate. RIA is used to measure rare serum proteins like Human growth harmon, glucagon, vasopressin, testosterone, and insulin. Also used in some test for illegal drugs.
Do you need to grow a culture to use a nucleic probe? Why or Why not?
No because you only need a single DNA strand and the probe will complementary base pair if they are a match.
What do epidemiologists study? Who would they most likely work for?
People who study occurrence, distribution, and determinants of health and disease in a population. They figure out what caused the disease and how it spread. Their main purpose is prevention. They would most likely work for: CDC, Public Health, NIH, and WHO.
Define epidemic, pandemic, endemic, incidence, and prevalence. Give examples.
Epidemic is when a disease occurs in an unusually large number of people in a population at the same time. (ex. swine flu, meningitis) Pandemic is widespread and usually world wide. (ex. small pox) Endemic is a disease that is constantly present in a population, usually at low incidences. (ex, colds and viruses) An incidence is the number of new cases of the disease in a given period of time. Prevalence is the total number of new and existing cases in a population in a given time.
What are carriers? Give examples
Carriers are sub-clinically infected individuals who may spread a disease. ex. Typhoid Mary
What is mortality and morbidity?
Mortality is the incidence of death in a population. Morbidity refers to the incidence of disease including fatal and nonfatal diseases.
Explain the basic progression of a disease.
infection is when the organism invades and colonizes the host. Incubation period is the period of time b/w infection and the onset of symptoms. Acute period is the disease at it's height. Decline period is when the disease symptoms are subsiding. Convalescent period is when the patient regains strength and returns to normal.
What is a reservoir? What is the natural reservoir for Mycobacterium leprae? Clostridium botulinum?
Reservoir is the sites in which infectious agents remain viable and from which infection of individuals can occur. Reservoir for mycobacterium leprae is armadillos, and the reservoir for clostridium botulinum is soil.
What is zoonoses? Give examples.
any disease that primarily infects animals, but is occasionally transmitted to humans ex. rabies
Who was Typhoid Mary? What was her real name? What was her story?
Typhoid Mary's real name was Mary Mallone. She was a cook with Typhoid fever before antibiotics existed. Salmonella typhi lived in her gallbladder. Bile went into her intestines infecting her with salmonella. She was a cook who did not wash her hands; therefore, she spread typhoid fever through the food. she killed about 5 people.
What are some examples of direct host to host transmission diseases? Indirect?
Direct: flu, common colds, STDs, and ringworm Indirect: vectors = mosquitos fomites = drinking glass, tissues, toys, cell phones, door handles, television remote, ties, and stethoscopes.
What is a vector? Fomite? Give examples
vectors are living agents that transfer a pathogen. fomites are an inanimate object that when contaminated with a viable pathogen can transfer the pathogen to the host.
how is a common source epidemic different from a host to host epidemic?
Common-source epidemic usually arises from contamination of water or food (ex. cholera), and with host to host epidemic the disease shows a slow progressive rise and gradual decline (ex. influenza and chicken pox)
What is a herd immunity? How does it work?
It is the resistance of a group to infection due to immunity of a high proportion of the members of the group. (refer to figure 33.6)
What groups are at greatest exposure to HIV?
80% Female Heterosexual contact & 67% Male to Male sexual contact
Are people in Africa or America more likely to die of infectious diseases? Why?
Africa b/c they lack access to antibiotics and preventative health care
What is the leading cause of death in America?
32% cardiovascular disease & 19% cancer
What are emergent and reemerging disease? Give Examples
Emergent: diseases that suddenly come prevalent Reemerging: those that have become prevalent after having been previously under control (get exs)
What are biological weapons? Which organisms could be used?
organisms or toxins that are easy to produce and deliver. They are safe for use by the offensive soldiers and able to incapacitate or kill individuals under attack in a consistent and reproducible manner. ex. bacillus anthracis (anthrax)
What is a nonsocomial infection? Give examples.
Nonsocomial is a healthcare associated infection; results from an infectious agent acquired during admission to a healthcare facility, which wasn't present upon admission. ex. went to the hospital for surgery and came back with staph/ urinary tract infection
What factors increase the risk of nonsocomial infections?
Many patients have low resistance to infectious disease, healthcare facilities treat infectious disease patients, multiple patients in the same room, healthcare personnel move from patient to patient, healthcare procedures may breach the skin and introduce the infection, newborn infants are susceptible to infection, surgical procedures expose organs to contamination, certain drugs increase a patients susceptibility to infection, use of antibiotics has selected or antibiotic resistant organisms
What are the two most common body sites for nonsocomial infections?
32% urinary tract infections & 22% surgical infections
What public health measures are used to precent diseases?
Immunization: small pox, rubella, and tetanus. Quarantine: restricts the movement of an individual with an active infection. Surveillance: observation, recognition, and reporting of diseases. Pathogen Eradication: Goal is to remove all of a pathogen from any reservoir. (ex. small pox, polio, and potentially rabies, leprosy, and others.
What are the three types of anthrax? How do you acquire each and why does it kill you? What organism causes anthrax? What type of bacteria is this and why would it make a good weapon?
1. Cutaneous anthrax (come in contact through skin) 2. Gastrointestinal anthrax (ingest; causes diarrhea) 3. Pulmonary anthrax (breath it in) bacillus anthracis causes anthrax. It makes a good weapon because it is easy to produce and deliver and vaccination is only done on people at risk.
What is an aerosol? What type of pathogens are spread by aerosols?
Aerosols are important vehicles for person to person transmission of many infectious diseases. Respiratory infections are spread by airborne.
What is GAS? What causes strep throat? How could you diagnose it? What are the common characteristics of all streptococci compared to staphylococci? What characteristics are unique to streptococcus pyogenes?
*find out how to diagnose it! streptococcus pyogenes(Group A streptococcus; GAS) is the causative agent of strep throat. Streptococci: Gram +, chains, catalase - (no bubbles if you pour H202 on a cut) staphylococci: catalase + (bubbles) Gram + Strep pyogenes:It does have a capsule but it also produces toxins. it produces beta hemolysins that completely lyse the red blood cells. (bacitracin sensitive - antibiotic) (Not sure)
What is impetigo? Erysipelas?
Impetigo is indian fire; caused by staph & strep. Erysipelas is and infection of the skin from A. S. pyogenes. It is caused by beta hemolytic strep and is a skin infection on the face, known as st. Anthony's fire.
What makes S. pyogenes so virulent? What does it mean that it carries a lysogenic bacteriophage?
It does have a capsule but it also produces toxins. it produces beta hemolysins that completely lyse the red blood cells. Certain GAS strains carry a lysogenic bacteriophage that encodes exotoxins responsible for symptoms of toxic shock syndrome and scarlet fever.
What causes scarlet fever and rheumatic fever?
scarlet fever is caused by streptococcus pyrogens that carry a lysogenic bacteriophage. Rheumatic fever is caused by untreated or insufficiently treated infections.
what does streptococcus pneumonia cause? What is the site of infection and what makes this organism pathogenic?
streptococcus pneumonia is the causative agent of pneumonia. The site site of infection is the lungs/lower respiratory tracts. The capsule makes it pathogenic b/c it helps to prevent being destroyed by phagocytes.
What cause diptheria? What type of organism is it? how does it cause disease? Is it preventable and how is it treated?
Diptheria is caused by corneybacterium diptheria. It is spread by air borne droplets and enters the body through the respiratory route. Yes, it is preventable. It is treated with antibiotics. Diptheria antitoxin is available for acute cases.
What is pertussis? What causes it? How is it prevented? What is a cough plate?
Pertussis also known as whopping cough us an acute highly infectious respiratory diesease. It is caused by an infection with bordetella pertussis and is prevented by administration of vaccine right after birth. (not finished answering)
What is the etiological agent of tuberculosis? Hansen's disease? What is another name for Hansen's disease? What is unique about these organisms?
Tuberculosis and Hansen's disease are both caused by mycobacteria. Tuberculosis is caused by mycobacteria tuberculosis. Hansen's disease which is also known as Leprosy is caused by M. Leprae. Something that is unique about these organisms is that they are acid fast due to the waxy mycolic acid content of their cell walls.
How is tuberculosis treated? How is it spread? How is it diagnosed? What does a positive tuberculin test mean? Why are we seeing an increase in the number of antibiotic resistant strains?
Tuberculosis is treated by antimicrobial therapy with isoniazid. Treatment usually requires a 9 month regiment. It is transmitted by airborne droplets. it is diagnosed by a sputum sample. Positive tuberculin test cd mean several things such as: could have TB, you were exposed to TB but didn't get infected or you had TB vaccine. If you get a positive skin test and were not vaccinated then an x-ray is done and if it comes out positive an aputan sample acid fast test is done. There is an increase in the number of antibiotic resistant strains due to the emergence of drug-reisistant strains.
How is leprosy spread? Does it grow very fast?
by direct contact & respiratory routes. No, delayed hypersensitivity
What is meningitis? What causes it? How is it diagnosed? How is it spread?
Meningitis is an inflammation of the meninges; membranes that line the central nervous system, especially the spinal cord and brain. can be caused by viral, bacterial, fungal, or protist infections spread through airborne routes. Need cerebral spinal test to diagnose it and treatment is usually achieved with penicillin G.
What causes rubeola measles? How is it prevented?
caused by a neg. strand RNA virus called a paramyxovirus. prevented by immunizations
What is a characteristic symbol of mumps?
inflammation of the salivary glands
what group of people are of great concern not get German measles? Why?
Pregnant women b/c it can cause birth defects/child death.
What is MMR and DPT?
MMR =Measles, Mumps, and Rebellum. DPT=Diptheria, Pertussis and Tetanus
Explain the disease process for chicken pox and shingles. What causes them and are they contagious.
Chicken pox (varicella) is caused by varicella zoster virus (VZV), a DNA herpes virus. Varicella/chicken pox is the initial infection. It is latent and hides in the nerves. When it comes back, it comes back as shingles, which is contagious, but a person with shingles infects others with the chicken pox.
Compare and contrast colds and flu including etiological agents.
Colds are viral infections transmitted through airborne droplets usually short duration. Commonly caused by Rhinoviruses, 15% coronaviruses, and 10% adenoviruses. Influenza is caused by an RNA virus of orthomyxovirus. (A, B, and C) **Refer to chart for comparison
What do coronaviruses and adenoviruses cause?
Coronaviruses = 15% of colds and SARS Adenoviruses = 10% of colds and respiratory infections
What is antigenic shift and antigenic drift? Why do they occur and which virus are they associated with?
Antigenic shift:L major change in influence virus antigen due to gene reassortment Antigenic drift: minor change in influenza virus antigens due to gene mutation (get rest of answer. )
How does the flu vaccine protect you from getting the flu?
**Get answer