Antimicrobial agents include a wide variety of medications that kill pathogens, agents that cause disease. They target bacteria, fungi, viruses and parasites. Antibiotics kill bacteria, antifungals kill fungi, antivirals kill viruses and antiparasitics kill parasites.
Antibiotics are the most well known of the antimicrobial agents. They include drugs like penicillin, tetracycline and azithromycin. Amantadine and oseltamivir are antiviral agents useful against influenza, while acyclovir treats outbreaks caused by the herpes virus. Antifungal drugs include miconazole, which treats gential yeast infections, and clotrimazole, which treats athlete's foot. Finally, antiparasitic agents include drugs such as itazoxanide, which treats symptoms of infestation with Giardia lamblia.
Antibiotic resistance is an important consideration in the treatment of infectious diseases, but it applies to all antimicrobial agents. Resistance occurs when a pathogen changes, and no longer responds to an antimicrobial drug. In other words, a drug no longer kills the previously susceptible pathogen. Causes of resistance include the inappropriate prescription of antimicrobial drugs, and the improper use of antimicrobial drugs once they are prescribed.
An example of inappropriate prescribing would be writing a prescription for antibiotics for a patient with a viral infection. Antibiotics are only effective against bacteria, not viruses. An example of improper use would be not finishing a course of antibiotics because the symptoms of infection cleared up after a few days.