ANTIBIOTICS- chemicals that inhibit specific proteins or enzyme systems for

bacteria—to deal with each new threat. treatment of a specific infection.

 Gram-positive bacteria are those
 Antibiotics are made in three ways: By
whose cell wall retains a stain known
living microorganisms, by synthetic
as Gram stain or resists decolorization
manufacture, and in some cases
with alcohol during culture and
through genetic engineering
sensitivity testing. Gram-positive
 Antibiotics may either be
bacteria are commonly associated
bacteriostatic (preventing the growth
with infections of the respiratory tract
of bacteria) or
and soft tissues. An example of a
bactericidal (killing bacteria directly)
Grampositive bacterium is
MAJOR CLASSES OF ANTIBIOTICS Streptococcus pneumoniae, a
common cause of pneumonia.
o Aminoglycosides  Gram-negative bacteria are those
o Carbapenems whose cell walls lose a stain or are
o Cephalosporins decolorized by alcohol. These bacteria
o Fluoroquinolones are frequently associated with
o Penicillin infections of the genitourinary (GU) or
o Penicillinase resistant drugs GI tract. An example of a Gram-
o Sulfonamides negative bacterium is Escherichia coli,
o Tetracyclines a common cause of cystitis
o Disease-specific antimycobacterial,  Aerobic bacteria depend on oxygen
including the antitubercular and for survival, whereas Anaerobic
leprostatic drugs. bacteria do not use oxygen

BACTERIA AND ANTIBIOTICS BACTERIA AND RESISTANCE TO

ANTIBIOTICS
 Bacteria can invade the human body
through many routes, for example,  Bacteria have survived for
respiratory, gastrointestinal (GI), and hundreds of years because they
skin. Once the bacteria invade the can adapt to their environment.
body, the human inflammatory They do this by altering their cell
response is activated, and signs and wall or enzyme systems to
symptoms of an infection occur as the become resistant to (e.g., protect
body tries to rid itself of the foreign themselves from) unfavorable
cells conditions or situations. Many
 Fever, lethargy, slow-wave sleep species of bacteria have
induction, and the classic signs of developed resistance to certain
inflammation (e.g., redness, swelling, antibiotics.
heat, and pain) all indicate that the  For example, bacteria that were
body is responding to an invader. once very sensitive to penicillin
 The goal of antibiotic therapy is to have developed an enzyme called
decrease the population of invading penicillinase, which effectively
bacteria to a point at which the inactivates many of the penicillin-
human inflammatory/immune system type drugs.
can effectively deal with the invader.  The longer an antibiotic has been
To determine which antibiotic will in use, the greater the chance
effectively interfere with the specific that the bacteria will develop into
a resistant strain. Efforts to
 control the emergence of aminoglycosides in the treatment of
resistant strains involve intensive less serious infections.
educational programs that - Aminoglycosides include amikacin
advocate the use of antibiotics (generic), gentamicin (generic),
only when necessary and effective neomycin (generic), streptomycin
and not for the treatment of viral (generic), and tobramycin (Bethkis,
infections such as the common TOBI, Tobrex Ophthalmic).
cold. - THERAPEUTIC ACTION- They inhibit
 The Food and Drug Administration protein synthesis in susceptible
(FDA) and Centers for Disease strains of Gram-negative bacteria.
Control and Prevention (CDC) They irreversibly bind to a unit of the
have joined efforts to educate the bacteria ribosomes, leading to
public and healthcare providers misreading of the genetic code and
about the dangers of cell death.
inappropriate use of antibiotics. - INDICATION- treatment of serious
infections that are susceptible to penicillin
KEY POINTS
when penicillin is contraindicated, and
 The goal of antibiotic therapy they can be used in severe infections
is to reduce the population of before culture and sensitivity results have
invading bacteria to a size been obtained.
that the human immune - CONTRAINDICATIONS- Known allergy to
response can deal with. any of the aminoglycosides; renal or
 Bacteria can be classified as hepatic disease that could be exacerbated
Gram-positive (frequently by toxic aminoglycoside effects and that
found in respiratory could interfere with drug metabolism and
infections) or Gram-negative excretion, leading to higher toxicity;
(frequently found in GI and preexisting hearing loss, which could be
GU infections). intensified by toxic drug effects on the
 They can also be classified as auditory nerve; active infection with
anaerobic (not needing herpes or mycobacterial infections that
oxygen) or aerobic could be worsened by the effects of an
(dependent on oxygen). aminoglycoside on normal defense
 Culture and sensitivity testing mechanisms.
ensures that the correct - CAUTIONS- necessary when these agents
antibiotic is chosen for each are administered during pregnancy
infection, a practice that may because aminoglycosides are used to
help to decrease the number treat only severe infections, and the
of emerging resistant-strain benefits of the drug must be carefully
bacteria weighed against potential adverse effects
on the fetus.
AMINOGLYCOSIDE - are a group of powerful -
antibiotics used to treat serious infections
caused by Gram-negative aerobic bacilli.

- Because most of these drugs have

potentially serious adverse effects,
newer, less-toxic drugs have replaced
CARBAPENEMS - are a relatively new class of
broad-spectrum antibiotics effective against
Gram-positive and Gram-negative bacteria.

- Carbapenems discussed here include

doripenem (Doribax), ertapenem
(Invanz), imipenem–cilastatin
(Primaxin), meropenem (Merrem IV),
and meropenem–vaborbactam
(Vabomere), the newest form that
combines meropenem with a beta-
lactamase inhibit