CHAPTER 9 Flashcards
actually refers to
the use of any chemical (drug) to treat any disease or condition.
chemotherapy
The chemicals (drugs) used to treat diseases are
referred to as
chemotherapeutic agents.
is any chemical (drug)
used to treat an infectious disease, either by inhibiting or
killing pathogens in vivo.
antimicrobial
agent
Drugs used to treat bacterial
diseases are called
antibacterial agents,
is a substance produced
by a microorganism that is effective in killing or inhibiting the growth of other microorganisms.
antibiotic
examples of antibiotics produced by
moulds;
Penicillin and
cephalosporins
antibiotics that have been chemically modified to kill a wider variety of pathogens or reduce side
effects; these modified antibiotics are called
semisynthetic
antibiotics.
discovered that the red dye, Prontosil, was ef-
fective against streptococcal infections in mice.
Gerhard
Domagk
The five most common mechanisms of action of
antimicrobial agents are as follows:
- Inhibition of cell wall synthesis
- Damage to cell
membranes - Inhibition of nucleic acid synthesis (either DNA or
RNA synthesis) - Inhibition of protein synthesis
- Inhibition of enzyme activity
drugs that inhibit production of folic acid
Sulfonamide
they kill either
Gram-positive or
Gram-negative
bacteria,
Narrow spectrum
antibiotics
they kill both
Gram-positives and
Gram-negatives.
broad spectrum
antibiotics
the only narrow-spectrum antibiotic
vancomycin
these agents stop bacteria from growing and dividing.
bacteriostatic agents
Bacteriostatic agents should not be used in
or leukopenic patients (patients having
an abnormally low number of white blood cells).
they interfere with the synthesis of bacterial
cell walls and have maximum effect on bacteria that are
actively dividing.
Penicillins
The cephalosporins are clas-
sified as
first-, second-, third-, and fourth-generation
cephalosporins
these ____ generation agents are
active primarily against Gram-positive bacteria.
First gen
___generation cephalosporins have increased activity against
Gram-negative bacteria,
second
____generation cephalo-
sporins have even greater activity against Gram-negatives
(including Pseudomonas aeruginosa).
Third
what is an example of a fourth generation cephalosphorin
Cefepime
broad-spectrum drugs
that exert their effect by targeting bacterial ribosomes.
Tetracyclines.
are effective
against a wide variety of bacteria, including chlamydias,
mycoplasmas, rickettsias, Vibrio cholerae, and spirochetes
like Borrelia spp. and T. pallidum.
Tetracyclines.
are bactericidal broad-
spectrum drugs that inhibit bacterial protein synthesis.
Aminoglycosides.
They are used to treat infections with members
of the family Enterobacteriaceae (e.g., Escherichia coli
Aminoglycosides.
inhibit protein synthesis. They are considered bacteriostatic at lower doses and bacte-
ricidal at higher doses.
Macrolides
bactericidal
drugs that inhibit DNA synthesis.
Fluoroquinolones.
The use of two antimicrobial agents to treat an infectious disease sometimes produces a
degree of pathogen killing
synergism.
When the use of two
drugs produces an
extent of pathogen
killing that is less than
that achieved by either
drug alone, the
phenomenon is known
as
antagonism.
tend to be more toxic
to the patient because,
like the infected
human, they are
eucaryotic organisms.
fungal & protozoal pathogens
Most
antifungal agents work in one of
three ways:
By binding with cell membrane sterols
- By interfering with sterol synthesis
- By blocking mitosis or nucleic acid synthesis
drugs that are usually quite toxic to the host and work by (a) interfering with DNA and RNA synthesis or interfering with protozoal metabolism
ANTIPROTOZOAL AGENTS
The first antiviral agent effective against human
zidovudine
refer to an organism that is resistant to only one antimicrobial
agent, the term usually refers to multiply drug-resistant
organisms
“superbug”
examples of superbugs
viruses, fungi, protozoa, helminths
the drug is unable to cross the organism’s cell wall or cell membrane and, thus, cannot reach its site of action. this resistance is called
intrinsic resistance
bacteria that were once susceptible to a particular drug to become resistant to it; this is called
acquired resistance.
drug must first bind (attach) to proteins on the surface of the cell; these protein molecules are called
drug-
binding sites.
a potentially dangerous type of staph bacteria that is resistant to antibiotics
MRSA
The primary way in which bacteria acquire new genes is by
CONJUGATION
A plasmid containing multiple genes for drug
resistance is called a
resistance factor
superbug). Bacteria can also acquire new genes by
transduction
enables the cell to pump drugs out of the cell before the drugs
can damage or kill the cell.
MDR pump
penicillin molecules have The “garage” is called the
B lactam ring
bacteria
produce enzymes that destroy the -lactam ring; these enzymes are known as
B -lactamases.
There are two types of -
lactamases:
penicillinases and
cephalosporinases.
initiate therapy before
laboratory results are available.
empiric therapy
provides important information regarding drugs to which various bacterial pathogens were susceptible and resistant
pocket
chart
UNDESIRABLE EFFECTS OF
ANTIMICROBIAL AGENTS
organisms within that patient that are sus-
ceptible to the agent will die,
The patient may become allergic to the agent.
Many antimicrobial agents are toxic to humans,
may de-
stroy the normal flora of the
mouth, intestine, or vagina.
The resultant overgrowth by such organisms ;a “population explosion” of organisms that are usually present only in small numbers. is referred
to as a
superinfection.
Which of the following is least likely to be taken into
consideration when deciding which antibiotic to
prescribe for a patient?
a. patient’s age
b. patient’s underlying medical conditions
c. patient’s weight
d. other medications that the patient is taking
c
Which of the following is least likely to lead to drug
resistance in bacteria?
a. a chromosomal mutation that alters cell mem-
brane permeability
b. a chromosomal mutation that alters the shape of
a particular drug-binding site
c. receiving a gene that codes for an enzyme that
destroys a particular antibiotic
d. receiving a gene that codes for the production of a capsule
d
Which of the following is not a common mechanism
by which antimicrobial agents kill or inhibit the
growth of bacteria?
a. damage to cell membranes
b. destruction of capsules
c. inhibition of cell wall synthesis
d. inhibition of protein synthesis
b
Multidrug therapy is always used when a patient is
diagnosed as having:
a. an infection caused by MRSA.
b. diphtheria.
c. strep throat.
d. tuberculosis.
d
- Which of the following terms or names has nothing
to do with the use of two drugs simultaneously?
a. antagonism
b. Salvarsan
c. Septra
d. synergism
b
Which of the following is not a common mechanism
by which antifungal agents work?
a. by binding with cell membrane sterols
b. by blocking nucleic acid synthesis
c. by dissolving hyphae
d. by interfering with sterol synthesis
c
Which of the following scientists is considered to be
the “Father of Chemotherapy?”
a. Alexander Fleming
b. Paul Ehrlich
c. Selman Waksman
d. Sir Howard Walter Florey
a
- All the following antimicrobial agents work by inhibiting cell wall synthesis except:
a. cephalosporins.
b. chloramphenicol.
c. penicillin.
d. vancomycin.
b
All the following antimicrobial agents work by in-
hibiting protein synthesis except:
a. chloramphenicol.
b. erythromycin.
c. imipenem.
d. tetracycline.
c
