Treatment of Infectious Disease

Antimicrobial agents Chemical substances that either kill microbes or prevent their growth Term “antibiotic” literally means “destroyer of life: Most common term to refer to a drug used to treat bacterial infections Can be either microbistatic or microbicidal Microbistatic-inhibits or prevents the growth of microbes Microbicidal-kills the microbe

Treatment of Bacterial Diseases Relatively easy to find and develop drugs that treat bacterial diseases These drugs target structural functions and metabolic characteristics of the bacteria. Can be grouped into categories based on mode of action

Mode of Action Inhibit cell wall synthesis Inhibit protein synthesis Inhibit nucleic acid synthesis Or inhibit some other chemical reaction

Penicillins Mode of action: interferes with cell wall Treats: ear infections, sepsis, wound infections, etc Important to take all of the prescribed medication

Cephalosporins Mode of action: interferes with cell wall synthesis Treats: skin and soft tissue infections, and can be used in place of penicillin if allergy is present

Tetracycline Inhibits protein synthesis Treats: H.pylori, skin infections, UTI’s and STD’s Can have severe side effects including interfering with bone formation in a developing fetus

Rifampicin Inhibits RNA synthesis Treats: Tuberculosis Can stain contact lenses

Erythromycin Inhibit protein synthesis Treats: endocarditis, rheumatic fever, and gonorrhea Can make skin more sensitive to sunlight Can be toxic if used in high doses for prolonged periods of time

Sulfonomides Interferes with nucleic acid synthesis Treats: kidney infections and other UTI’s Can have allergic reactions

Treatment of Viral Illnesses Drugs that inhibit viral infections are highly toxic to host cells because viruses use the host’s metabolism Most illnesses due to virus are treated symptomatically until the immune system eliminates the virus

Antiviral drugs Antiviral drugs typically target virus specific enzymes in nucleic acid synthesis

Acyclovir Inhibits nucleic acid synthesis Treats: herpes simplex viruses including Herpes Zoster viruses

Amantadine Antiviral used to prevent or decrease the symptoms of influenza among those that are at risk Inhibit replication of virus

AZT Inhibits the HIV genome Treats the symptoms of HIV Patients are also prescribed proteases that interfere with the packaging of the HIV genome into virus particles

Treatment of Fungal and Parasitic Diseases Challenging due to the toxicity to human tissue These medication target the pathogens’ replicative pathway

Antifungals Inhibit sterol synthesis or disrupt the cell membrane Treats: systemic fungal infections and histoplasmosis Can be toxic to human tissue.

Azole derivatives Targets the pathogen’s replicative pathway. Treatment of fungal and parasitic diseases.

Amphotericin B Inhibits the sterol synthesis or disrupts the cell membrane. Treats fungal infections.

Antihelminthic drugs Target adult worms that no longer replicate Mode of action: inhibit fundamental processes like muscle function Treats: helminth infectious in animals, trichinella spirialis and avermectins (lice)

Antiprotozoan drugs Malaria was successfully treated for years with chloroquine Recently, a certain species has become resistant to this drug In these areas, a combination of sulfonamide and pyrimethamine are used

Resistance to Antimicrobal Agents This has been an ongoing problem for the past 50-60 years. Microbes are constantly evolving, enabling them to efficiently adapt to new environments. Antimicrobial resistance is the ability of microbes to grow in the presence of a drug that would normally kill them or limit their growth.