chapter 26

Semisynthetic penicillins are generally more broad-spectrum than natural penicillins.

TRUE

Interferon is specific to the A) host cell. B) protein. C) virus. D) host cell and virus.

A) host cell.

Of all the known antibiotics that have been identified in nature, ________ are clinically useful. A) <1% B) 8-10% C) 18-20% D) 25-30%

A) <1%

Semisynthetic antibiotics A) are natural antibiotics that have been chemically modified in the laboratory. B) have an artificially constructed core that stimulates the production of "natural products." C) are found in nature, but their rate of production is enhanced in the laboratory. D) are natural antibiotics that have been purified by artificial means.

A) are natural antibiotics that have been chemically modified in the laboratory.

Polyoxins interfere with A) cell membrane synthesis. B) chitin biosynthesis. C) fungal mitosis. D) all of the above.

A) cell membrane synthesis.

The process by which macromolecules lose their structure and ability to function is called A) denaturation. B) sterilization. C) thermal death. D) none of the above.

A) denaturation.

In the agar diffusion method of studying antimicrobial action, the ________ is measured. A) diameter of the zone of inhibition B) diameter of the individual microbial colonies C) turbidity of the medium D) distance between the microbial colonies

A) diameter of the zone of inhibition

The quinolones are synthetic antibacterial compounds that A) inhibit bacterial DNA gyrase. B) increase the supercoiling rate in the bacterial DNA. C) prevent the formation of pre-RNA segments. D) do all of the above.

A) inhibit bacterial DNA gyrase.

Compared with decontamination, disinfection is A) more aggressive. B) less aggressive. C) equally aggressive. D) either more or less aggressive, depending on the situation in question.

A) more aggressive.

Erythromycin acts as a(n) A) protein synthesis inhibitor at the level of the 50S subunit of the ribosome. B) protein synthesis inhibitor at the level of the 30S subunit of the ribosome. C) nucleic acid enzyme inhibitor. D) inhibitor of ribosome production.

A) protein synthesis inhibitor at the level of the 50S subunit of the ribosome.

Highly active anti-retroviral therapy (HAART), which involves a combination of nucleoside analogs and protease inhibitors, is most commonly used to treat infections of A) drug resistant strains of bacteria. B) HIV. C) Mycobacterium tuberculosis. D) Staphylococcus aureus.

B) HIV.

Agents that kill bacteria are said to be A) inhibitory. B) bacteriocidal. C) bacteriostatic. D) all of the above.

B) bacteriocidal.

The action of some bacteriolytic chemical agents can be observed by noting a(n) A) increase in the turbidity of the medium. B) decrease in the turbidity of the medium. C) change in the color of the medium. D) change in the surface tension of the medium.

B) decrease in the turbidity of the medium.

UV radiation is antimicrobial, because A) radiation generates significant amounts of heat within the given cell. B) energy present causes modifications or breaks in the DNA molecules. C) radiation generates magnetic poles that denature the cellular components. D) all of the above are true

B) energy present causes modifications or breaks in the DNA molecules.

The B-lactam antibiotics A) inhibit plasma membrane synthesis. B) inhibit cell wall synthesis. inhibit protein synthesis. D) prevent chromosomal replication

B) inhibit cell wall synthesis.

A ________ filter is most often used to filter sterilize liquids. A) depth B) membrane C) nucleation track D) microbistat

B) membrane

The most successful agents used for antiviral chemotherapy are A) ATP reductase inhibitors. B) nucleoside analogs. C) nucleotide analogs. D) protein synthesis inhibitors.

B) nucleoside analogs.

The complete elimination of all microorganisms, including viruses, is called A) disinfection. B) sterilization. C) decontamination. D) any of the above, depending on the circumstances.

B) sterilization.

Which of the following antimicrobial treatments is affective only on exposed surfaces? A) microwaves B) ultraviolet rays C) X-rays and gamma rays D) electrons

B) ultraviolet rays

Common radioactive isotopes for sterilization are A) cobalt and potassium. B) cesium and potassium. C) cobalt and cesium. D) cobalt and iodine.

C) cobalt and cesium.

Cold sterilization is performed using A) exceptionally low temperatures. B) dry ice. C) compounds such as ethylene oxide. D) high-pressure chambers.

C) compounds such as ethylene oxide.

The time required for a tenfold reduction of the viability of a microbial population at a given temperature is called the ________ time. A) thermal death B) mean sterilization C) decimal reduction. D) temperature-dependent logarithmic death

C) decimal reduction.

Ergosterol inhibitors specifically target A) bacteria. B) eukaryotes. C) fungi. D) viruses

C) fungi

Neuraminidase inhibitors such as oseltamivir and zanamivir are used to treat which type of infection? A) bacterial B) fungal C) influenza virus D) parasitic

C) influenza virus

A ________ filter is most often used in scanning electron microscopy. A) depth B) membrane C) nucleation track D) microbistat

C) nucleation track

At present, the penicillins and the cephalosporins account for ________ of all the antibiotics produced and used worldwide. A) less than 10% B) about 25% C) over 50% D) well over 70%

C) over 50%

The vegetative cells of Mycobacterium tuberculosis are resistant to many germicides because of A) an extra membranous layer between the cell wall and the plasma membrane. B) the complex nature of the plasma membrane itself. C) the waxy nature of the cell wall. D) the lattice work found in the glycocalyx.

C) the waxy nature of the cell wall.

The thermal death time is the A) dose of radiation necessary for a tenfold reduction in the numbers of selected microorganisms or biological functions. B) measure of the radiation energy output from a source. C) time it takes to kill all cells at a given temperature. D) time required for a tenfold reduction in the population density at a given temperature

C) time it takes to kill all cells at a given temperature.

Which statement is TRUE about heat sterilization? A) Microbial death is more rapid at an acidic pH. B) High concentrations of sugars and salts influence sterilization time. C) The amount of water in a substance is a major factor in heat resistance. D) All of the above are true.

D) All of the above are true.

Which is NOT a reason why microorganisms may have an inherent natural resistance to an antibiotic? A) The organism may be impermeable to the antibiotic. B) The organism may be able to pump out an antibiotic entering the cell. C) The organism may be able to alter the antibiotic to an inactive form. D) The organism may be protected from the drug by its nuclear membrane

D) The organism may be protected from the drug by its nuclear membrane

Which of the following are classified as electromagnetic radiation? A) microwaves B) ultraviolet rays C) X-rays and gamma rays D) all of the above

D) all of the above

Antimicrobial drugs are often grouped according to A) molecular structure. B) spectrum of antimicrobial activity. C) mechanism of action. D) all of the above.

D) all of the above.

Important targets of antibiotics in Bacteria are A) the cell wall. B) the cytoplasmic membrane. C) DNA replication and transcription elements. D) all of the above.

D) all of the above.

Isoniazid interferes with the synthesis of the mycobacterial-specific mycolic acid cell wall material

TRUE

Because of their limited range of effectiveness, the fluoroquinolones are used primarily in treating infections caused by gram-positive Bacteria

FALSE

Because of their particulate nature, electrons are not considered a form of electromagnetic radiation

FALSE

Cephalosporins contain a double Ά-lactam ring, whereas the penicillins contain a single Ά-lactam ring

FALSE

Drug resistance to the sulfonamides has remained low while many other types of antibiotics have remained constant.

FALSE

Many countries, such as Australia, France, Germany, and the United States, decontaminate and sterilize certain foods with ionizing radiation.

FALSE

Pasteurization is synonymous with sterilization; the only difference is that the term pasteurization is used with heat sensitive foods.

FALSE

The purpose of decontamination methods is to eliminate microbial growth

FALSE

Many Neisseria gonorrhoeae strains have developed Ά-lactamases that cleave the Ά-lactam rings, which provides them with resistance to certain antibiotics

TRUE

Most attempts at chemical control of viruses result in toxicity for the host

TRUE

Radiation is a decontamination measure approved by the World Health Organization (WHO) for foods particularly susceptible to microbial contamination.

TRUE

A thermometer can be sterilized using a cold sterilization method.

TRUE

Antiseptics may either kill or inhibit the growth of microorganisms and are sufficiently nontoxic to be applied to living tissues.

TRUE

Bacteriolytic agents can inhibit cell wall synthesis

TRUE

Bacteriostatic agents inhibit bacterial growth but do not specifically kill the organisms against which they are directed

TRUE

Both cephalosporins and penicillins have the same mode of action, despite the two having different chemical structures.

TRUE

Endospore heat resistance is determined by the concentration of small acid-soluble proteins (SASPs) and water content of the endospore.

TRUE

Growth factor analogs that resemble nucleic acids are used in the treatment of viral and fungal infections.

TRUE

In general, vegetative cells are more heat resistant than bacterial endospores.

TRUE

In practice, sterility is difficult to achieve.

TRUE

The CDC has developed a 12-step prevention program for the prevention of resistance to antimicrobial agents aimed primarily for hospitalized individuals.

TRUE

The antimicrobial effects of microwaves are due, at least in part, to thermal effects.

TRUE

The first widely used growth factor analogs specifically designed to inhibit bacterial growth were the sulfa drugs.

TRUE

The term antimicrobial agent includes both fungicidal and fungistatic agents.

TRUE

The tetracyclines are protein synthesis inhibitors that specifically disrupt the function of bacterial 30S ribosome

TRUE