Micro Ch 19-20

Antimicrobials that kill microorganisms have the suffix

-cidal.

Antimicrobials that inhibit the growth of microorganisms have the suffix

-static.

Large respiratory droplets typically travel no farther from point of release than

1 meter.

Approximately what percentage of hospitalized patients may develop a nosocomial infection?

5%

The minimum bactericidal concentration is the lowest concentration of a specific antimicrobial drug that kills _______ of a specific type of bacteria.

99.9%

Which of the following is NOT a political/societal reason for a decrease in rates of childhood immunizations?

A lack of a proper 'cold chain' for stable transport of vaccines into tropical areas.

Why is it important to include a placebo in a scientific study to assess the effectiveness of a drug?

A placebo-treated group will determine if the changes observed in the drug-treated illness group are due to a psychological effect rather than a physiologic/pharmacologic one.

Antimicrobials may produce

All of the choices are correct.

Bacteria may become antibiotic resistant due to

All of the choices are correct.

Which of the following drugs target peptidoglycan?

All of the choices are correct.

Which of the following may be associated with nosocomial disease?

All of the choices are correct.

Compliance problems are leading to a large increase in antibiotic resistant strains of

Mycobacterium

Which of the following bacteria have an innate resistance to penicillin?

Mycoplasma

Why would antimicrobials that have toxic side effects be used at all (select the BEST reason)?

NOT Every person is different. What is toxic to one person may not be toxic to another person. To eliminate a useful drug because it's toxic to 1% of people treated is a waste.

Why are nucleoside analogs active only against replicating viruses?

Nucleoside analogs work by being incorporated into growing strands of DNA/RNA. This indirectly shuts down further extension of these chains. However, new strands of viral DNA/RNA are only being created when the virus is replicating. As such, these drugs can only work when the virus is actively replicating as well.

The rate of nosocomial infections is often relatively high in emergency room settings. Explain the most likely reason why this might be so.

Often, the most acutely ill or most traumatically-injured individuals are found in emergency rooms. The combination of these two groups can lead to very easy spread of infectious agents into exposed tissues/organs of individuals in such physical locations.

Sulfonamides are similar in structure to

PABA.

Why would co-administration of a bacteriostatic drug interfere with the effects of penicillin?

Penicillin interferes with cell wall production/stabilization by cross-linking of peptidoglycan. As such, it only works when the cells are actively replicating and MAKING new peptidoglycan. A bacteriostatic drug works by shutting down replication, holding the cells 'static.' This would interfere with the mode of action required by the penicillin.

Fluoroquinolones typically target

DNA gyrase

A commercial modification of the disk diffusion test is called the

E test.

One of the earliest researchers to explore the use of chemicals to kill microbial pathogens was

Ehrlich

Penicillin was discovered by

Fleming

The most effective form of penicillin is

G

In what clinical situation is it most appropriate to use a broad-spectrum antimicrobial?

In a case of bacterial meningitis. The infection spreads so quickly that we must treat it with an antibacterial drug as quickly as possible. We don't have time to determine which drug will work best, because the patient will die in the meantime

The arsenic compound that proved highly effective in treating syphilis was called

Salvarsan

The first example of an antimicrobial drug synthesized in the laboratory was

Salvarsan

The doctor responsible for introducing the idea of hand washing before attending patients was

Semmelweis

Explain the most likely reason why smallpox was successfully eradicated but rabies probably never will be.

Smallpox was ONLY found in humans; rabies is found in numerous animal reservoirs. We cannot reasonably eliminate rabies in all of the animal reservoirs that exist.

The guidelines designed for prevention of nosocomial disease during care of all patients is called

Standard Precautions.

Droplet nuclei typically travel no farther from point of release than

They are suspended indefinitely.

Which is true of aminoglycosides?

They irreversibly bind to the 30S ribosomal subunit AND they are bactericidal.

The World Health Organization (WHO) is part of the

United Nations

Which of the following groups of microorganisms produces antibiotics?

all of the choices are correct

The major class(es) of antibiotics that inhibit protein synthesis is/are

aminoglycosides, tetracyclines AND macrolides.

If drugs are less effective when taken together than when each is taken separately, they are called

antagonistic

The antimicrobials produced by some molds and bacteria are generally called

antibiotics

Penicillin-binding proteins

are enzymes AND are involved in cell wall synthesis.

Transmission-Based Precautions

are guidelines to use with patients infected with a highly transmissible or epidemiologically important pathogen.

Gonorrhea is a disease that may be

asymptomatic

The number of cases of a specific disease per one hundred people exposed is called the

attack rate.

Spontaneous development of resistance to a particular antimicrobial is difficult if the drug

binds to several sites on the target molecule AND targets several different molecules.

Prevention of patient-to-personnel transmission of disease keys on limiting contact with

body fluids.

Beta-lactamases

break the beta-lactam ring.

Antibiotics that affect various strains of Gram-positive bacteria and various strains of Gram-negative bacteria are called

broad-spectrum.

Antibiotics that are most likely to disrupt the normal flora are termed

broad-spectrum.

A new serotype of Vibrio cholerae, V. cholerae 0139, has picked up the ability to produce

capsules

Apparently healthy people who may transmit a pathogen they harbor are called

carriers

The use of Salvarsan and Prontosil to treat microbial infections were early examples of

chemotherapy

If the number of people who become ill during an epidemic rises and falls rapidly, this is called a(n)

common source epidemic. They are suspended indefinitely.

Diseases that can be transmitted from one person to another are termed

communicable

Sulfonamides work as

competitive inhibitors.

Schistosomiasis has increased in areas where

dams have been built.

The type of epidemiological study that determines the characteristics of the persons involved and the time and place of the outbreak is called a(n)

descriptive study.

The amount of infecting agent received by susceptible individuals is called the

dose

An experimental study in which neither the doctor nor the patient knows who is getting the actual treatment is called

double-blind.

Important sources of contamination in crowded locations are

droplets of saliva or mucus.

Diseases constantly present in a population are called

endemic

A dramatic increase in the incidence of a specific disease in a given population is referred to as a(n)

epidemic

The target of most antifungal drugs is

ergosterol

Sulfonamide and trimethoprim are both

examples of metabolic inhibitors AND folate inhibitors.

Which of the following is not a mechanical vector?

fomite

Inanimate objects capable of transferring infectious disease agents are

fomites

The immunity of some black Africans to malaria is probably due to their

genetic background.

Which of the following is recommended by the Standard Precautions guidelines?

glove use, hand washing AND a face shield

When an infectious disease cannot spread in a population because it lacks a significant number of susceptible hosts, the phenomenon is referred to as

herd immunity

The period of time between exposure to an agent and the onset of disease signs and symptoms is called the

incubation period.

The first identified case in an outbreak is called the

index case.

The member of the hospital staff who surveys the types and numbers of nosocomial infections is called the

infection control practitioner.

Drugs that are bacteriostatic

inhibit bacterial growth

The threat of bioterrorism

is due largely to the ease of spread and severity of diseases AND may include rarely seen infectious agents.

The diffusion bioassay

is similar in principal to the Kirby-Bauer test AND determines the concentration of antimicrobial in a fluid.

A high therapeutic index is

less toxic to the patient.

The lowest concentration of a drug that prevents growth of a microorganism is the

minimum inhibitory concentration.

The fraction of a population who die from a specific disease is called

mortality rate.

An infection acquired during hospitalization is referred to as

nosocomial

A cluster of cases in a specific population occurring in a brief period of time is called a(n)

outbreak

An epidemic that spreads worldwide is called a(n)

pandemic

Which of the following is called a zoonotic disease?

plague

WHO has targeted for elimination of

polio, dracunculiasis AND measles.

Vertical transmission involves

pregnant woman to fetus.

Another name for childbed fever is

puerperal fever

The natural habitat of a pathogen is referred to as its

reservoir

Inhibitors of protein synthesis typically key on

ribosomes

An antibiotic made by microorganisms and modified by chemists is called

semi-synthetic.

So far, the only disease that has been globally eradicated is

smallpox

The reservoir of infection for botulism and tetanus is

soil

Because of the natural evolution of microorganisms, it is necessary to use techniques that allow distinguishing them at the level of

strain

One of the earliest antimicrobials isolated from a bacterium was

streptomycin

Prontosil effectively acted on streptococci when the drug was split by enzymes to produce

sulfanilamide

Drugs that are more effective when taken together are called

synergistic

Trimethoprim and sulfonamides have a(n)

synergistic effect.

The toxicity of a given drug is expressed as the

therapeutic index.

Antiviral drugs may target

uncoating, nucleic acid synthesis AND viral assembly

Diseases that primarily exist in animals, but may be transmitted to humans are called

zoonotic

Explain how using a combination of two antimicrobial drugs helps prevent the development of spontaneously resistant mutants.

It is highly unlikely that the microbe might spontaneously develop 2 specific mutations to resist the effects of a pair of drugs. As such, even if one drug is resisted by the microbe, the 2nd drug will eliminate the mutated microbe, thus preventing the development of spontaneously resistant mutants overall.

Which test is used to determine the susceptibility of a microorganism to an antimicrobial?

Kirby-Bauer test

Mycolic acids are targeted by isoniazid in the treatment of

M. tuberculosis.

The publication of the CDC that reports new cases of reportable infectious diseases is titled

Morbidity and Mortality Weekly Report (MMWR).

If the number of people who become ill during an epidemic rises gradually, this is called a(n)

Propagated epidemic

The most common method of transfer of antimicrobial resistance is through the use of

R plasmids.