ANTI-INFECTIVE AGENTS

Nelia B. Perez RN, MSN

Northeastern College

Santiago City 3311

Anti Infectives

• Drugs that are designed to act selectively on foreign organisms that have invaded and infected the body of a human host.

• Toxic to the infecting organisms only and not to the host cells.

ANTI INFECTIVE THERAPY

• 1920s – Paul Ehrlich was the 1st scientist to work on developing a synthetic chemical that would be effective only against infection-causing cells, not human cells.

• Late 1920s – scientist discovered penicillin in a mold sample.

• 1935 – sulfonamides are introduced.

Mechanisms of Action

• Some anti-infectives interfere with biosynthesis of the bacterial cell wall.

• Some anti-infectives prevent the cells of the invading organism from using substances essential to their growth and development.

• Many Anti-infectives interfere with the steps involved in protein synthesis, a necessary function to maintain the cell and allow for cell division.

• Some anti-infectives interfere with DNA synthesis in the cell, leading to inability to divide and cell death.

• Other anti-infectives alter the permeability of the cell membrane to allow essential components to leak out, causing cell death.

ANTI-INFECTIVE ACTIVITY

• Bacteriostatic

• Bactericidal

HUMAN IMMUNE RESPONSE• Goal of anti-infective therapy is

reduction of the population of the invading organisms to a point at which the human immune response can take care of the infection.

ACQUIRING RESISTANCE

• Producing an enzyme that deactivates the antimicrobial drug.

• Changing cellular permeability to prevent the drug from entering the cell or altering transport systems to exclude the drug from active transport into the cell.

• Altering binding sites on the membrane or ribosomes which then no longer accept the drug.

• Producing a chemical that acts as an antagonist to the drug.

Preventing resistance

• Doses would be high enough and the duration of drug therapy should be long enough to eradicate even slightly resistance microorganisms.

• Prevent indiscriminate use of anti- infectives.

Treatment of Systemic infections• Identification of Pathogens

• Sensitivity of Pathogens

• Combination Therapy

Adverse Reactions of Anti-Infective Therapy• Kidney Damage

• Gastrointestinal Toxicity

• Neurotoxicity

• Hypersensitivity Reactions

• Superinfections

Prophylaxis

• Prevents infection before they occur.

ANTIBIOTICS

Antibiotics

• Chemicals that inhibit specific bacteria.

BACTERIA AND ANTIBIOTICS• Goal of antibiotic therapy is to decrease

the population of the invading bacteria to a point at which the human immune system can be effectively deal with the invader.

• Gram-positive bacteria are those whose cell wall retains a stain, known as Gram’s stain, or resists decolorization with alcohol during culture and sensitivity testing.

• Gram-positive bacteria are commonly associated with respiratory tract infection and of soft tissues.

• Gram – negative bacteria are those whose cell walls lose a stain or are decolorized by alcohol.

• Frequently associated with infections of the genitourinary or GI tract.

• Aerobic Bacteria depend on oxygen for survival.

• Anaerobic bacteria do not use oxygen to survive.

Aminoglycosides

• Group of powerful antibiotics used to treat serious infections caused by gram-negative aerobic bacilli.

Amikacin

• Available for short-term intramuscular or intravenous use for serious gram negative infections.

• Potential for nephrotoxicity and ototoxicity with amikacin is very high, so the drug is used only as long as absolutely necessary.

Gentamicin

• Available in many forms.

• Covers a wide variety of infections, including pseudomonal diseases and once-rare infections seen in patients with acquired immune deficiency syndrome (AIDS).

Kanamycin

• Available in parenteral and oral forms.• Used in treating hepatic coma when

ammonia-producing bacteria in the GI tract cause serious illness.

• It is also use as an adjunctive therapy to decrease GI bacterial flora.

• Should not be used for longer than 7-10 days because of potential toxic effects, which include renal damage, bone marrow depression and GI complications

Neomycin

• Slightly milder aminoglycosides that is used to suppress GI bacteria preoperatively and to treat hepatic coma.

• In topical form, it is used to treat skin wounds and infections.

STREPTOMYCIN

• Very toxic to the eight cranial nerve and kidney.

• Used in PTB chemotherapy.

Tobramycin

• Used for short term IM or IV treatment of very serious infections.

• Also available in an ophtalmic form for the treatment of ocular infections caused by susceptible bacteria.

Therapeutic Actions and Indications• Bactericidal• Inhibit protein synthesis in susceptible

strains of gram-negative bacteria, which in turn leads to loss of functional integrity of bacterial cell membrane, causing cell death.

• Indicated for the treatment of serious infections that are susceptible to penicillin when penicillin is contraindicated and they can be used in severe infections before culture and sensitivity tests have been completed.

Pharmacokinetics

• Aminoglycosides are poorly absorbed in the GI tract.

• Rapidly absorbed after IM injection.

• Widely distributed in the body.

• Crosses the placenta and enters the breast milk

• Excreted unchanged in the urine.

Contraindications and Cautions

• Known allergy to any of the aminoglycosides

• Renal or hepatic disease• Pre-existing hearing loss• Active infection with herpes or

mycobacterial infections• Myasthenia gravis or parkinsonism• Lactation• pregnancy

ADVERSE EFFECTS

• CNS: ototoxicity, irreversible deafness, vestibular paralysis, confusion, depression, disorientation, numbness, tingling and weakness.

• RENAL: toxicity, renal failure, bone marrow depression