Bio 28: Microbiolgy Bronx Community College Exam 2 (9,10,11 & 12)

one phosphate, one nitrogenous base, and one sugar

Each nucleotide is composed of

one helix strand that runs from the 5' to 3' direction and the other strand runs from the 3' to 5' direction

The antiparallel arrangement within DNA molecules refers to

leading strand

The strand of new DNA that is synthesized in a continuous manner in the 5′ to 3′ direction.

lagging strand

The strand of new DNA that must be synthesized in short segments (in a 5′ to 3′ direction) and later sealed together to form a strand in the 3′ to 5′ direction.

Okazaki fragments

The short segments of DNA synthesized in a 5′ to 3′ direction, which are then sealed together to form a 3′ to 5′ strand

Which antibiotic is used to treat MRSA and VRE infections?

A) synercid

B) linezolid

C) azithromycin

D) clarithromycin

E) clindamycin

linezolid

Sulfa drugs work on

A) folic acid biosynthesis.

B) nucleic acid biosynthesis.

C) ribosome biosynthesis.

D) peptidoglycan biosynthesis.

Acyclovir is used to treat infections caused by:

A) hepatitis C virus.

B) respiratory syncytial virus.

C) herpes simplex virus.

D) HIV.

E) influenza A virus

Herpes Simplex Virus

The use of vaginal inserts of Lactobacillus to restore a healthy acidic environment is an example of

A) phytobiotics.

B) lantibiotics.

C) riboswitches.

D) prebiotics.

E) probiotics.

Probiotics

Ketoconazole, fluconazole, clotrimazole, and miconazole are broad-spectrum azoles used to treat ________ infections.

viral

helminthic

bacterial

protozoan

fungal

The cellular basis for bacterial resistance to antimicrobials include

alteration of drug receptors on cell targets.

bacterial chromosomal mutations.

prevention of drug entry into the cell.

synthesis of enzymes that alter drug structure.

All of the choices are correct.

Which of the following blocks HIV binding to host cell receptors?

acyclovir

AZT

Fuzeon

amantidine

nevirapine

Fuzeon

In a conversation with your friends from microbiology class, you are talking about drug resistance. The three of you disagree about the definition of the term so each of you state his or her definition and give a justification. Compare the various definitions and justifications below and pick the one that is most accurate.

The drug is changed in the body and is inactivated physically and chemically so it no longer works properly against the bacterium.

The bacterium has changed physically or chemically in some way to be able to destroy the drug or avoid its action, allowing it to grow unimpeded by the drug.

The bacterium becomes immune to the drug: the drug no longer kills or inhibits the bacterium.

The person becomes resistant to the drug: The body adjusts to the dosage of the chemical and no longer responds to its action.

A drug exhibiting which therapeutic index value would be the safest, most effective to use on a patient?

10

0.1

20

1

Any choice would be equally effective.

Ampicillin, amoxicillin, mezlocillin, and penicillin G all have

a beta-lactam ring.

a semisynthetic nature.

an expanded spectrum of activity.

resistance to the action of penicillinase.

a beta-lactam ring.

Antimicrobials effective against a wide variety of microbial types are termed

A) synthetic drugs.

B) antibiotics.

C) semisynthetic drugs.

D) broad-spectrum drugs.

E) narrow-spectrum drugs.

broad-spectrum drugs

The antifungal drug that can be used to treat serious systemic fungal infections is

A) griseofulvin

B) sulfa drugs

C) metronidazole

D) nystatin

E) amphotericin B

amphotericin B

Which of these drugs has the most narrow-spectrum activity?

A) aminoglycosides

B) isoniazid

C) erythromycin

D) tetracycline

E)cephalosporins

Microbial resistance resulting from mutation occurs because

mutations are passed between organisms.

prokaryotic genomes undergo mutation often.

prokaryotic genomes undergo mutation rapidly.

short generation times accumulate mutations in populations.

All of the choices are correct.

Which of the following is not used to treat malaria?

meflaquine

chloroquine

quinine

metronidazole

primaquine

metronidazole

Which of the following is not true of polymyxins?

narrow spectrum

source is Bacillus polymyxa

target cell walls

toxic to kidneys

can treat severe urinary tract infections caused by gram-negative bacilli

target cell walls

The ________ are drugs that deposit in developing teeth and cause a permanent brown discoloration.

penicillins

macrolides

cephalosporins

streptomycins

tetracyclines

tetracyclines

Antibiotics are derived from all of the following except

Bacillus.

Streptomyces.

Penicillium.

Staphylococcus.

Cephalosporium.

Infections caused by gram-negative bacilli are often treated with

penicillin G.

synercid.

isoniazid.

aminoglycosides.

vancomycin.

Each of the following contributes to emerging drug resistance except

ingestion of antibiotics with animal feed.

overuse of antibiotics.

addition of antibiotics to common household products.

multiple drug therapy.

improper use of antibiotics

multiple drug therapy

Which of the following antibacterial drug groups does not target protein synthesis?

macrolides

sulfonamides

tetracyclines

oxazolidinones

aminoglycosides

Which drug is used to treat cases of tuberculosis?

isoniazid

tetracycline

penicillin G

vancomycin

synercid

Mebendazole, thiabendazole, and ivermectin are drugs used to treat ________ infections.

helminthic

viral

bacterial

fungal

protozoan

helminthic

Important characteristics of antimicrobial drugs include

stable and soluble in body tissues and fluids.

low toxicity for human tissues.

high toxicity against microbial cells.

do not cause serious side effects in humans.

All of the choices are correct.

All of the choices are correct

Aminoglycosides

block peptidases that cross-link glycan molecules.

interfere with elongation of peptidoglycan.

are metabolic analogs of PABA and block folic acid synthesis.

attach to the 30S ribosomal subunit and disrupt protein synthesis.

damage cell membranes.

block peptidases that cross-link glycan molecules.

Your patient has been on antibiotics for 6 weeks after a case of streptococcal endocarditis, an infection of the inner heart wall. The infection clears up. However, the patient just visited you about a urinary tract infection, and the lab verified that the culprit was E. coli. What do you hypothesize happened in this situation?

The antibiotics damaged her immune system, making her very susceptible to environmental bacteria.

The lab has made a mistake in identifying the cause, and, in fact, the endocarditis was caused by the E. coli.

Her normal microbiota in the genitourinary tract were killed, allowing E. coli (not killed by the antibiotics) to establish an infection.

The lab has made a mistake in identifying the cause, and, in fact, the UTI was caused by the original Streptococcus.

Her normal microbiota in the genitourinary tract were killed, allowing E. coli (not killed by the antibiotics) to establish an infection.

Selective toxicity refers to damage to

prokaryotic cell membranes.

pathogenic organisms.

the target organisms but not vertebrate cells.

nucleic acids.

the target organisms but not vertebrate cells

A ratio of the dose of the drug that is toxic to humans versus the minimum effective dose for that pathogen is assessed to predict the potential for toxic drug reactions. This is called the

Kirby-Bauer technique.

therapeutic index (TI).

E-test.

antibiogram.

minimum inhibitory concentration (MIC)

therapeutic index (TI)

A clinical microbiologist makes serial dilutions of several antimicrobials in broth, and then incubates each drug dilution series with a standard amount of a patient's isolated pathogen. What is this microbiologist setting up?

therapeutic index (TI)

antibiogram

E-test

Kirby-Bauer technique

minimum inhibitory concentration (MIC) test

minimum inhibitory concentration (MIC) test

The drug that is used to treat typhoid fever and brain abscesses, but can cause aplastic anemia, is:

gentamicin.

bacitracin.

clindamycin.

chloramphenicol.

ciprofloxacin.

The drug used for several protozoan infections is

metronidazole.

nystatin.

amphotericin B.

griseofulvin.

sulfa drugs.

metronidazole

Which of the following is not an aminoglycoside?

gentamicin

tobramycin

tetracycline

amikacin

streptomycin

A superinfection results from

build up of a drug to toxic levels in the patient.

the wrong drug administered to the patient.

an immune system reaction to the drug.

a decrease in most normal biota resulting in the overgrowth of an unaffected species.

a decrease in most normal biota resulting in the overgrowth of an unaffected species

The use of a drug to prevent imminent infection is called

competitive inhibition.

prebiotics.

synergism.

prophylaxis.

lantibiotics.

prophylaxis

There are fewer antifungal, antiprotozoan, and antihelminthic drugs compared to antibacterial drugs because fungi, protozoa, and helminths

do not cause many human infections.

are not affected by antimicrobials.

fewer target sites in their cells compared to bacteria.

are parasites found inside human cells.

are so similar to human cells that drug selective toxicity is difficult to achieve.

Antiviral drugs that target reverse transcriptase would be used to treat infections caused by:

HIV.

influenza A virus.

respiratory syncytial virus.

hepatitis C virus.

herpes zoster virus.

HIV

Penicillins and cephalosporins

block peptidases that cross-link glycan molecules.

attach to the 30S ribosomal subunit and disrupt protein synthesis.

are metabolic analogs of PABA and block folic acid synthesis.

damage cell membranes.

interfere with elongation of peptidoglycan.

block peptidases that cross-link glycan molecules

The patient has a staphylococcal infection of the blood, a septicemia—very serious and possibly deadly. As the doctor, you would like to prescribe a relatively non-toxic and inexpensive drug out of the cephalosporin family. However, if the patient harbors a strain of Staphylococcus that is resistant to a variety of antibiotics, you would prefer to use vancomycin—which is highly effective against Staphylococcus. Which of the following explains why the cephalosporin drug is preferred for use over the vancomycin?

You would rather give an inexpensive drug to save the family money.

Vancomycin is one of the most selectively toxic drugs there is, so you would prefer one that has a more broad-spectrum effect.

Vancomycin is very toxic, and the Staphylococcus strain could become resistant leaving no back-up drugs with which to treat the infection.

You really do not know that much about vancomycin, so you would rather go with a drug that you can find out more about.

Vancomycin is one of the most selectively toxic drugs there is, so you would prefer one that has a more broad-spectrum effect.

Side effects that occur in patient tissues while they are on antimicrobial drugs include all of the following except

development of resistance to the drug.

hepatotoxicity.

deafness.

nephrotoxicity.

diarrhea.

development of resistance to the drug

Which of the following is not a mode of action of antiviral drugs?

block maturation

inhibit DNA synthesis

bond to ergosterol in the cell membrane

block penetration

block transcription and translation

bond to ergosterol in the cell membrane

Sulfonamides

block peptidases that cross-link glycan molecules.

interfere with elongation of peptidoglycan.

attach to the 30S ribosomal subunit and disrupt protein synthesis.

are metabolic analogs of PABA and block folic acid synthesis.

damage cell membranes.

Each of the following affect cell walls except

cycloserine.

penicillin.

cephalosporin.

erythromycin.

vancomycin.

erythromycin

Each of the following target prokaryotic ribosomes except

tetracycline.

erythromycin.

streptomycin.

gentamycin.

polymyxins.

polymyxins.

What type of chemical will allow some bacteria to be resistant to many penicillins?

clavulanic acid

penicillinase

imipenem

aztreonam

synercid

penicillinase

Which of the following is not used to treat malaria?

meflaquine

chloroquine

quinine

metronidazole

primaquine

quinine

Alcohols A) are skin degerming agents.

B) denature proteins when in a 50-95% alcohol-water solution.

C) disinfect items when soaking method is utilized.

at 50% or higher concentrations dissolve cell membrane lipids.

D) All of the choices are correct.

D) All of the choices are correct.

Which of the following germicides is/are also sporicidal? chlorine

Betadine

phenolics

chlorhexidine

chlorine, chlorhexidine, and Betadine

Which control method would not be a suitable choice for killing Mycobacterium in a capped culture tube?

gamma rays

ultraviolet (germicidal) light

121°C at 15 psi for 15 minutes

160°C for 2 hours

All of the choices are correct.

Which control method would not be a suitable choice for killing Mycobacterium in a capped culture tube?

gamma rays

ultraviolet (germicidal) light

121°C at 15 psi for 15 minutes

160°C for 2 hours

All of the choices are correct.

Heavy metals work by rupturing the cell membrane.

dissolving the cell wall.

binding to DNA.

inactivating proteins.

mutating DNA.

Endospores can be inactivated by

incineration.

ethylene oxide for 3 or more hours.

glutaraldehyde for 3 or more hours.

dry heat at 170°C for 2 hours.

All of the choices are correct.

All of the choices are correct

Sterilization is achieved by flash pasteurization.

steam autoclave.

boiling water.

hot water.

All of the choices are correct.

The compound that is an organic base containing chlorine and two phenolic rings, and is used increasingly for wound degerming, neonatal washes, hand scrubbing, and prepping surgical skin sites is triclosan.

formalin.

carbolic acid.

chlorhexidine.

quaternary ammonium compounds.

The use of chemical agents directly on exposed body surfaces to destroy or inhibit vegetative pathogens is sanitization.

sterilization.

disinfection.

antisepsis.

Antisepsis

The use of a physical or chemical process to destroy vegetative pathogens on inanimate objects is sterilization.

antisepsis.

degermation.

disinfection.

sanitization.

degermation

A method for sterilizing milk, called ________ treatment, uses 134? C for 1 to 2 seconds.

ultra high temperature

flash pasteurization

tyndallization

batch pasteurization

pasteurization

Aniline dyes like crystal violet have antimicrobial activity particularly against gram-positive bacteria and some fungi.

TRUE

FALSE

The presence of organic matter such as saliva and pus can interfere with the actions of disinfectants. TRUE

FALSE

The sterilizing gas used in chemiclaves is

formaldehyde.

chlorine dioxide.

glutaraldehyde.

ethylene oxide.

iodophor.

The method of removing vegetative microbial life forms and debris to reduce contamination to safe levels is termed

disinfection.

antisepsis.

sanitization.

sterilization.

decontamination.

Ionizing radiation is more effective than nonionizing radiation in killing or inactivating microbes. TRUE

FALSE

In lab, inoculating loops are sterilized using

incineration.

filtration.

chemicals.

moist heat.

gas sterilization.

Organisms in the genus Pseudomonas are resistant to quats.

TRUE

FALSE

Ethylene oxide is a halogen.

only effective with high heat.

the active agent in household bleach.

sporicidal.

used as an antiseptic against anaerobes.

Chlorine dioxide and ethylene oxide are sterilizing gases.

TRUE

FALSE

The removal of all life forms from inanimate objects is termed

disinfection.

antisepsis.

degerming.

decontamination.

sterilization.

________ radiation excites atoms to a higher energy state within molecules such as DNA that then leads to the formation of pyrimidine dimers. Ionizing

Particle

Infrared

Gamma

Ultraviolet

The alcohol wipe used on a patient's skin before an injection is an example of decontamination.

sanitization.

sterilization.

disinfection.

antisepsis.

Which of the following microbial forms has the highest resistance to physical and chemical controls?

naked viruses

protozoan cysts

yeast

bacterial endospores

fungal spores

Dry Heat

is used in devices called autoclaves.

will sterilize at 121°C for 15 minutes.

cannot sterilize.

is less efficient than moist heat.

includes tyndallization.

The minimum sterilizing conditions in a steam autoclave are

160°C for 2 hours.

100°C for 30 minutes.

121°C at 15 psi for 15 minutes.

63°C for 30 minutes.

71.6°C for 15 seconds.

Your friend Joe recently visited the doctor for steroid injections into his knee to reduce swelling due to previous knee injury. Within a couple of days, he had an infection caused by Pseudomonas, a very pathogenic and drug resistant bacterium. Luckily, Joe went to the doctor immediately and received antibiotics. The doctor tells him that problem has occurred to many other people across the U.S. Predict the most likely cause of this situation: The needles were re-used and already contaminated before being used on the patients.

The steroid was contaminated at the production plant, so all batches of that drug made at that plant were contaminated with the bacterium.

The bacterium is normally on the skin of people, so can easily access the patient's blood during the needle stick.

The staff giving the steroid injections did not use proper aseptic technique.

Hydrogen peroxide is bactericidal.

sporicidal.

virucidal.

fungicidal.

All of the choices are correct.

________ is a control method that removes microorganisms rather than inhibiting or killing them. Filtration

Radiation

Disinfection

Boiling

Sterilization

The lowest temperature needed to kill or inactivate all microbes in 10 minutes is the thermal death point (TDP).

thermal death time (TDT).

sporicidal time.

death phase point.

Which of the following is not true of glutaraldehyde?

does not damage plastics

is classified as a carcinogen

inactivates endospores in 3 hours

cross-links proteins on cell surfaces

inactivates viruses

Which of the following items are typically irradiated in order to kill microbes? surgical gloves

operating room air

cured meats

human tissues such as heart valves and skin

All of the choices are correct.

________ solution was introduced in the late 19th century for preventing gonococcal infections in a newborn's eyes after exposure to the mother's infected birth canal. Merthiolate

Zinc oxide

Betadine

Silver nitrate

Triclosan

Each of the following is a target of antimicrobial agents except

cellular proteins.

cell membranes.

ribosomes.

cell walls.

cytoplasm.

Antimicrobial agents can target the cell wall by

blocking its synthesis.

denaturing proteins.

digesting it.

All of the choices are correct.