Microbiology Learning catalytics lecture 12-26

Why are penicillins more effective against Gram positive bacteria?

Gram positive bacteria have a thick layer of peptidoglycan and Gram positive bacteria lack an outer membrane Gram positive bacteria have a much thicker layer of peptidoglycan and lack the protection of an outer membrane. Both of these characteristics make them more susceptible to the effects of penicillins.

Gram-negative bacteria are more susceptible to cytolysis. Why?

Gram-negative cells have a thin layer of peptidoglycan The thin layer of peptidoglycan makes Gram-negative cells more susceptible to cytolysis. This thin layer offers little protection for the cell membrane of Gram-negative cells. Gram-positive cells, on the other hand, possess thick peptidoglycan layers which will protect their membranes from cytolysis.

Which of the following are characteristics of the innate immune system?

Present at birth Always available Early-warning system Not organisms-specific No memory response

Which of the following are characteristics of the adaptive immunity?

Specific response to a particular microbe Response to a microbe that has breached the innate defenses Organism-specific Slower to respond Memory response Involves lymphocytes

A sample of cerebrospinal fluid from a patient with meningitis was found to contain Gram positive diplococci. What is the probable causative organism of this infection?

Streptococcus pneumoniae

The MMR vaccine is a live-attenuated vaccine. This means that the vaccine contains...

a weakened form of the virus

Name the process that uses nitrate as an electron acceptor.

anaerobic respiration

What two processes contribute to the need for annual influenza vaccinations?

antigenic drift and antigenic shift

Which region of the skin supports the largest bacterial population?

armpits

What type of immunity is generated by the MMR (measles, mumps & rubella) vaccine?

artificially acquired and active Vaccines are a form of artificially acquired, active immunity. Antigens are introduced into the body via the vaccine, activating the humoral and cellular immune responses.

Antibiotics that inhibit protein synthesis have side effects...

at the 70S ribosomes in eukaryotic cells 70S ribosomes are present in the mitochondria of eukaryotic cells. Because these ribosomes resemble prokaryotic ribosomes, they will be affected by the antibiotic.

What is the first step in bacteriophage infection of a bacterial cell?

attachment

Why can frequent douching be a predisposing factor for many vaginal infections?

douching can disrupt the normal microbiota of the vagina

The form of nitrogen present in significant levels in the atmosphere is easily assimilated by most organisms.

false

What process do lactic acid bacteria use to convert glucose into lactic acid?

fermentation

Name a differential stain that could be used for bacterial identification

gram stain, acid-fast stain, endospore stain

How did EHEC acquire many of its virulence factors?

horizontal gene transfer

What is the name of the protein produced by Shigella that induces the rearrangement of the host cytoskeleton, allowing the bacteria to enter the host cells?

invasins

If a patient has a positive tuberculin skin test, do they have an active case of TB?

it is impossible to tell

During respiration, where is CO2 produced?

krebs cycle

The ability of microbes to ferment different compounds is used to produce a variety of foods. Which of the following are possible products of fermentation?

lactic acid, acetic acid, carbon dioxide, ethanol

Where in the GI tract do you expect to find the highest number of microbes?

large intestine

Would you consider shingles to be an acute, latent, or persistent infection?

latent

What type of vaccine is the Sabin vaccine?

live attenuated vaccine

Jason's doctor tells him that he has an infection caused by Salmonella enterica. She indicates that he should start to feel better in a few days, but that he needs to stay hydrated. Which stage of the disease is Jason currently in?

period of illness

Name the process by which bacteria acquire new characteristics due to infection by a bacteriophage and incorporation of viral DNA.

phage conversion

What type of organisms are green and purple sulfur bacteria?

phototrophs and autotrophs

How does urease activity benefit Helicobacter pylori?

neutralizes stomach acid

Thorough cooking or reheating of food will prevent all of the following EXCEPT...

staphylococcal food poisoning Bacillus cereus gastroenteritis

What is the function of the lysosome in a eukaryotic cell?

storage of digestive enzymes The lysosome stores digestive enzymes. This ensures that the cell does not accidentally damage itself with these enzymes. During phagocytosis, the lysosome fuses with the phagosome to form the phagolysosome. The ingested bacterial cell is then degraded and destroyed by the digestive enzymes from the lysosome.

Where does the energy for carbon fixation come from?

sunlight

Both antigenic shift and drift contribute to the need for annual flu vaccinations.

true Antigenic shift and drift can both alter the antigens presented on the surface of the virus. These changes mean that different strains of the virus will predominate in different year. Thus, different vaccines must be developed every year to account for the different antigens. Antigenic shifts are larger changes that are often associated with pandemics due to new combination of antigens being presented on the virus.

Jason's doctor indicates that he likely acquired this infection due to food he had consumed. What type of transmission is this?

vehicle transmission Foodborne transmission, as demonstrated in this outbreak, is a type of vehicle transmission

Which of the following statements about phage conversion and specialized transduction are TRUE?

-Both phage conversion and specialized transduction can give new traits to the recepient cell. -Specialized transduction involves transfer of bacterial DNA from the donor cell to the recipient cell via bacteriophage. -Phage conversion involves insertion of only viral DNA into the recipient cell chromosome.

Which of the following describes how a pathogenic bacterium may be affected by antibodies?

-The antibodies may stick to multiple bacteria, causing them to clump together. -The antibodies may stick to the bacterial cells, tagging the bacterial cells for phagocytosis -The antibodies may block proteins necessary for binding to the host cells. -The antibodies may bind to the bacterial cell and trigger activation of complement proteins.

psychotrophs

0-30

mesophiles

10-50

thermophiles

40-72

hyperthermophiles

65-110

Which of the following statements is true?

A successful pathogen doesn't kill its host before it is transmitted The primary goal of a pathogen is to survive and be transmitted. While some pathogens may kill the host, a successful pathogen will not kill the host without first being transmitted to a new host.

Including Jason, 261 confirmed Salmonella cases were recorded in 24 states. No single restaurant or restaurant chain was found to be associated with the outbreak. Epidemiologists compared the foods eaten by 53 affected individuals and 53 unaffected individuals in order to determine the source of the infections. What type of study is this?

Analytical epidemiology and Case-control study This is a case-control study. The diets of affected an unaffected individuals were compared to identify the source of the infections. Case-control studies are a type of analytical epidemiology.

Which of the following would not be considered a verified exception to Koch's postulates?

Corynebacterium diphtheriae causes the formation of a characteristic grayish membrane in the throat of an infected host

Jason is a 28 year-old man. Yesterday, he started experiencing a headache, fever, nausea, and diarrhea. Which of these are signs of a disease and which are symptoms?

Headache - Symptom Fever - Sign Nausea - Symptom Diarrhea - Sign Signs of a disease are objective changes that can be observed or measured by others (fever, diarrhea). Symptoms are subjective changes that a patient feels (nausea, headache). They can not be measured or observed by others.

Triple antibiotic ointment contains polymyxin B, neomycin, and bacitracin. What three antimicrobial actions are represented in this ointment?

Inhibition of cell wall synthesis Inhbition of protein synthesis Injury to plasma membrane

Why is penicillin not used to treat tetanus?

The disease symptoms are caused by a toxin and Treatment with penicillin causes the bacteria to release more toxin

Which of Koch's postulates can not be applied to bacterial vaginosis caused by Gardnerella vaginalis?

The pathogen from pure culture must cause the disease when it's inoculated into a healthy, susceptible host

Antibiotics can kill Gram negative bacteria, but symptoms of infection may worsen immediately after the start of treatment. Why?

Treatment with antibiotics causes the release of more endotoxins, worsening the symptoms. Endotoxins are formed as part of the cell wall in Gram negative bacteria. These endotoxins are released when the cells die. Treatment with antibiotics kills the cells, causing a release of more endotoxins in the host. This can lead to a worsening of the symptoms in the host because the endtoxins induce the symptoms in the host.

Which of the following illnesses are treated with antibiotics?

bacterial meningitis and leprosy

UTI agar consists of peptone, chromogenic mix, and agar. Is it chemically defined, complex, selective, and/or differential? Select all that apply.

complex and differential

Purified proteins from Bordetella pertussis is used in a(n)...

conjugated vaccine