Chapter 20: Antimicrobial Drugs

Ionophores

________ are antibiotics produced by several soil bacteria and fungi.

Phages

________ are specific for their host bacteria and may be useful to treat antibiotic- resistant infections.

Gram negative bacteria

________ are relatively more resistant to antibiotics because of the nature of their cell wall, which restricts absorption of many molecules to movements through openings called porins.

Penicillinases

________ are enzymes produced by many bacteria, most notably Staphylococcus species, that cleave the β- lactam ring of the penicillin molecule.

Antimicrobial drugs

________ are either bactericidal (they kill microbes directly) or bacteriostatic (they prevent microbes from growing)

Phage therapy

________ has been used in Russia, Georgia, and Poland for more than 50 years.

Bacteriophages

________ are viruses that can kill their host bacterial cells.

Destruction

________ or inactivation by enzymes mainly affects antibiotics that are natural products, such as the penicillins and cephalosporins.

Isoniazid

________ (INH) is a very effective synthetic antimicrobial drug against Mycobacterium tuberculosis.

own defenses

In bacteriostasis, the hosts ________, such as phagocytosis and antibody production, usually destroy the microorganisms.

antibiotic resistance

Tests are necessary only when susceptibility isnt predictable or when ________ problems develop.

Chloramphenicol

________ inhibits the formation of peptide bonds in the growing polypeptide chain by reacting with the 50S portion of the 70S prokaryotic ribosome.

Antibiotics

________ that affect a broad range of gram- positive or gram- negative bacteria are therefore called broad- spectrum ________.

Dilution tests

________ are often highly automated.

chemotherapeutic agent

If the ________ is effective, a zone of inhibition forms around the disk after a standardized incubation.

amphibians

Many birds, ________, plants, and mammals often produce antimicrobial peptides.

growth of pathogens

The normal microbiota ordinarily compete with and check the ________ or other microbes.

Strains of bacteria

________ that are resistant to antibiotics are particularly common among hospital workers, where antibiotics are in constant use.

Microorganisms

________ are not the only organisms that produce antimicrobial substances.

class of β lactam

The carbapenems are a(n) ________ antibiotics that substitute a carbon atom for a sulfur atom and add a double bond to the penicillin nucleus.

synthesis of bacterial plasma membranes

The ________ requires the synthesis of fatty acids as building blocks.

Penicillins

________ extracted from cultures of Penicillium fungi are the so- called natural penicillins.

Viral infections

________ are also particularly difficult to treat because the pathogen is within the human hosts cells and because the genetic information of the virus is directing the human cell to make viruses rather than to synthesize normal cellular materials.

large number of semisynthetic penicillins

A(n) ________ have been developed in attempts to overcome the disadvantages of natural penicillins.

Penicillins

________ prevent the cross- linking of the peptidoglycans, which interferes with the final stages of the synthesis of the cell walls, primarily of gram- positive bacteria.

dilution test

A broth ________ is often useful in determining the MIC and the minimal bactericidal concentration (MBC) of an antimicrobial drug.