Antibiotic Medications Definition

Drugs that kill bacteria and certain other microorganisms. Antibiotic medications are the mainstay of treatment for bacterial infection. Broad-spectrum antibiotics are capable of killing numerous types of bacteria; narrowspectrum antibiotics kill specific types or strains of bacteria.

There are seven primary classifications of antibiotic medications-aminoglycosides, cephalosporins, macrolides, quinolones (fluorquinolones), penicillins, sulfonamides, and tetracyclines-that contain over 100 different drugs.

Common Antibiotic Medications

COMMON ANTIBIOTIC MEDICATIONS
Aminoglycosides
gentamicinneomycintobramycin
Cephalosporins
cefaclorcefadroxilcefepime
cefdinircefoperazonecefoxitin
cefprozilcefprozilceftazidime
cefuroximecephalexincephradine
loracarbef
Macrolides
azithromycinclarithromycinerythromycin
Quinolones (Fluoroquinolones)
cinoxacinciprofloxacinenoxacin
gatifloxacinlevofloxacinlomefloxacin
moxifloxacinnalidixic acidnorfloxacin
ofloxacinsparfloxacintrovafloxacin
Penicillins
amoxicillinamoxicillin/clavulanatepenicillin V potassium
Sulfonamides
cotrimoxazoletrimethoprimtrimethoprim/sulfamethoxazole
Tetracyclines
doxycyclineminocyclinetetracycline

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 antibioticrelated diarrhea and oral or vaginal candidiasis (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 MEDICATIONSANTIVIRAL MEDICATIONS.

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