Encyclopedia of Health and Medicine

308 Infectious Diseases
COMMON ANTIBIOTIC MEDICATIONS
Aminoglycosides
gentamicin neomycin tobramycin
Cephalosporins
cefaclor cefadroxil cefepime
cefdinir cefoperazone cefoxitin
cefprozil cefprozil ceftazidime
cefuroxime cephalexin cephradine
loracarbef
Macrolides
azithromycin clarithromycin erythromycin
Quinolones (Fluoroquinolones)
cinoxacin ciprofloxacin enoxacin
gatifloxacin levofloxacin lomefloxacin
moxifloxacin nalidixic acid norfloxacin
ofloxacin sparfloxacin trovafloxacin
Penicillins
amoxicillin amoxicillin/ penicillin V
clavulanate
potassium
Sulfonamides
cotrimoxazole trimethoprim trimethoprim/
sulfamethoxazole
Tetracyclines
doxycycline minocycline tetracycline
How These Medications Work
Antibiotics are either bacteriocidal (kill bacteria
directly) or bacteriostatic (kill bacteria by preventing
them from reproducing). Some antibiotics are
effective against anaerobic bacteria (bacteria that
thrive in low-oxygen environments) and others
against aerobic bacteria (bacteria that require normal
atmospheric oxygen concentrations to survive).
Just as the strains of bacteria share common
traits yet have distinguishing features, the antibiotics
within a particular class have similarities and
differences. Doctors match bacteria and antibiotic
for greatest EFFICACY. Individual variations among
people also influence antibiotic effectiveness.
Therapeutic Applications
Antibiotic medications are effective for treating
bacterial infections. They have no effect on viral
infections or fungal infections. Laboratory analysis
of fluid or tissue samples, called culture and sensitivity,
is usually necessary to determine whether
an infection is bacterial. The analysis involves
attempting to grow the bacteria in the laboratory,
then determining which antibiotics can kill the
bacteria. Types of bacteria are sensitive to specific
classes of antibiotics, so knowing the general classification
of the bacteria is generally sufficient for
the doctor to prescribe an antibiotic medication
that will kill it.
Risks and Side Effects
Antibiotic medications have numerous side
effects, ranging from HYPERSENSITIVITY REACTION
(allergy) to LIVER or kidney damage. Allergy to
penicillin is the most common DRUG allergy. Some
antibiotics diminish the effectiveness of oral contraceptives
(birth control pills). Most antibiotics
increase the possibility for fungal (yeast) infection
because they disturb the balance of NORMAL FLORA.
Common consequences of this effect are antibiotic-related
DIARRHEA and oral or vaginal CANDIDIA-
SIS (yeast infection of the mouth or vagina).
ANTIBIOTIC RESISTANCE is a significant concern.
Numerous strains of bacteria have adapted to
become resistant to the antibiotics commonly used
to treat the infections they cause. Factors that contribute
to antibiotic resistance include overprescribing
of antibiotics and failure to take antibiotic
medications for the full course of prescribed treatment.
These factors expose bacteria to antibiotics
without killing them, giving the bacteria opportunity
to adapt in ways that block the actions of the
antibiotics in future generations of the bacterial
strain. It is essential to take antibiotic medications
only when necessary and for the full course of
treatment.
See also ANTIBIOTIC PROPHYLAXIS; ANTIFUNGAL MED-
ICATIONS; ANTIVIRAL MEDICATIONS.
antifungal medications Drugs that kill fungi
(yeast). Antifungal medications are available for
topical or systemic treatment. Some fungal infections
require both. Antifungal medications work
through various mechanisms to interfere with the
ability of fungi to survive or reproduce. Broadspectrum
antifungal medications are effective for
treating a variety of fungal infections; narrow-