Chapter 38: Antibiotics Part 1 pg609 Flashcards
The patient usually manifests some
of the following classic signs and symptoms of infection:
fever,
chills, sweats, redness, pain and swelling, fatigue, weight loss,
increased white blood cell (WBC) count, and the formation of
pus.
methicillin-resistant Staphylococcus aureus
MRSA
disinfectant
kill organisms and is used only on nonliving objects
cidal agents
antiseptic
applied to living tissue
inhibits the growth of microorganisms
static agents
empiric therapy
The antibiotic selected is one that can
best kill the microorganisms known to be the most common
causes of the infection
definitive therapy
Once the results of culture and sensitivity
testing are available (usually in 48 to 72 hours), the antibiotic
therapy is then tailored to treat the identified organism by using
the most narrow-spectrum, least toxic drug based on sensitivity
results.
subtherapeutic when these signs
and symptoms do not improve. This can result from
use of an incorrect route of drug administration, inadequate drainage of
an abscess, poor drug penetration to the infected area, insufficient
serum levels of the drug, or bacterial resistance to the
drug.
Relatively minor adverse drug
reactions such as
nausea, vomiting, and diarrhea are quite common
with antibiotic therapy and are usually not severe enough
to require drug discontinuation
Superinfection can occur when antibiotics
reduce or completely
eliminate the normal bacterial flora, which consist of
certain bacteria and fungi that are needed to maintain normal
function in various organs
pseudomembranous colitis or simply C.
difficile infection. This happens because antibiotics
disrupt the
normal gut flora and can cause an overgrowth of Clostridium
difficile. The most common symptoms of C. difficile colitis are
watery diarrhea, abdominal pain, and fever
One of the more common
food-drug interactions
between milk or cheese and tetracycline,
which results in decreased GI absorption of tetracycline.
An example of a drug-drug interaction is that between
quinolone antibiotics and antacids or multivitamins with iron,
which leads to decreased absorption of quinolones
Drugs that cause development abnormalities in the fetus
are called
teratogens. Their use by pregnant women can result
in birth defects
The administration of antibiotics such as sulfonamides,
nitrofurantoin, and dapsone to a person with….
G6PD deficiency
may result in the hemolysis, or destruction, of red blood cells
Patients who are slow acetylators have a
physiologic makeup
that causes certain drugs to be metabolized more slowly than
usual in a chemical step known as acetylation. This can lead to
toxicity from drug accumulation
Antibiotics are classified into broad categories based on their
chemical structure. The common categories include
sulfonamides,
penicillins, cephalosporins, macrolides, quinolones,
aminoglycosides, and tetracyclines.
The four most common
mechanisms of antibiotic action are:
(1) interference with
bacterial cell wall synthesis, (2) interference with protein synthesis,
(3) interference with replication of nucleic acids (deoxyribonucleic
acid [DNA] and ribonucleic acid [RNA]), and
(4) antimetabolite action that disrupts critical metabolic reactions
inside the bacterial cell.
Sulfonamides p616
antimetabolites. bacteriostatic antibiotics preventing bacterial synthesis of folic acid Photosensitivity reactions
Sulfites are commonly used
as preservatives in
everything from wine to food to injectable drugs
The use of sulfonamides is also contraindicated in…
pregnant women at term and in infants younger than
2 months of age
named because of the beta-lactam ring that is part
of their chemical structure
includes four major subclasses: penicillins, cephalosporins,
carbapenems, and monobactams
they inhibit the synthesis of
the bacterial peptidoglycan cell wall.
penicillins
bactericidal antibiotics
classified as pregnancy category B drugs
enzymes capable of destroying penicillins
beta-lactamases
The enzyme can break the chemical bond
between the carbon (C) and nitrogen (N) atoms in the structure
of the beta-lactam ring
examples of currently available combinations of a
penicillin and a beta-lactamase inhibitor
- ampicillin/sulbactam (Unasyn)
- amoxicillin/clavulanic acid (Augmentin)
- ticarcillin/clavulanic acid (Timentin)
- piperacillin/tazobactam (Zosyn)
extended-spectrum penicillins are used to
treat many hospital-associated infections, including pneumonia,
intraabdominal infections, and sepsis.
patients with a history of throat swelling or
hives from penicillin should not receive
cephalosporins
The intravenous (IV) formulations of some penicillins contain
large amounts of
sodium and/or potassium
Cephalosporins
semisynthetic antibiotics
structurally and pharmacologically
related to the penicillins.
bactericidal
Cefoxitin and cefotetan are often
referred to as cephamycins and have better coverage against
SECOND-GENERATION
various anaerobic bacteria such as Bacteroides fragilis, Peptostreptococcus
spp., and Clostridium spp
Cefuroxime axetil
oral form only
is a prodrug. It has little antibacterial
activity until it is hydrolyzed in the liver to its active
cefuroxime form. oral form only
cephalosporins that is indicated
for the treatment of meningitis
Ceftriaxone (Rocephin)
unique in that it is metabolized in the intestine after biliary
excretion
Cefaroline (Teflaro) is the newest cephalosporin
only
cephalosporin that treats MRSA
have the broadest antibacterial action of any
antibiotics to date.
carbapenems, bactericidal.
Carbapenems must
be infused over 60 minutes
they are often reserved for complicated
body cavity and connective tissue infections
Imipenem/cilastatin is indicated for the treatment of
bone,
joint, skin, and soft-tissue infections; bacterial endocarditis
caused by S. aureus; intraabdominal bacterial infections;
pneumonia; UTIs and pelvic infections; and bacterial septicemia
caused by susceptible bacterial organisms
Aztreonam (Azactam) is the only monobactam antibiotic
synthetic beta-lactam antibiotic that is
primarily active against aerobic gram-negative bacteria, including
E. coli, Klebsiella spp., and Pseudomonas spp.
bacteriostatic.
There are three macrolide antibiotics
azithromycin, clarithromycin, and erythromycin
Macrolide antibiotics are bacteriostatic drugs that inhibit protein
synthesis by binding reversibly to the 50S ribosomal subunits of
susceptible microorganisms.
bacteriostatic; however, in
high enough concentrations they may be bactericidal
Fidaxomicin
(Dificid) is the newest macrolide antibiotic
indicated
only for the treatment of Clostridium difficle–
associated diarrhea
For drugs metabolized in the
liver, drug interactions arise from
competition between the different
drugs for metabolic enzymes, specifically the enzymes
known as the cytochrome P-450 complex
Examples of some especially common drugs that compete for
hepatic metabolism with the macrolides
are carbamazepine,
cyclosporine, theophylline, and warfarin.
When macrolides
are given with these drugs, the results are enhanced effects and
possible toxicity of the latter drugs, and patients must be monitored
