Antiinfectives - Infection Pathophysiology...

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ANTIBACTERIALS: Penicillins and Cephalosporins Infection Pathophysiology - Disease-producing organisms o Bacteria Gram +, gram – Bacterial cell wall differs in structure Bacilli: elongated, or rod-shaped Cocci: spherical Single-cell microorganisms o Viruses Smallest pathogen, toughest o Fungi Yeasts or mold, infect skin or subcutaneous tissue Antibacterials - Antibiotics
o Bacteriostatic drugs Inhibit growth of bacteria o Bactericidal drugs Kill bacteria o Mechanisms of action Alteration of permeability Inhibition of protein synthesis (RNA/DNA) Interference with cellular metabolism o Body defenses Age, nutrition, immunoglobulins, circulation, WBCs, organ function o Resistance to antibacterials Natural or inherent resistance Acquired resistance Nosocomial infections
Cross-resistance o Antibiotic combinations Additive : effect is doubled Potentiative : one potentiates effect of other Antagonistic : if one bactericidal and one bacteriostatic, desired effect is diminished o General adverse reactions Mild allergic reaction Rash, pruritus, hives Severe allergy: anaphylactic shock Bronchospasm, laryngeal edema, vascular collapse, cardiac arrest T reatment Antihistamine, epinephrine, bronchodilator o Superinfection Secondary infection: normal flora are killed
Sites: mouth, skin, respiratory tract, vagina, intestines Usually occurs when treated more than 1 week o Organ toxicity Liver, kidney, ear Spectrum o Narrow spectrum Primarily effective against one bacteria type Examples: penicillin, erythromycin o Broad spectrum Effective against gram + and gram – Examples: tetracycline, cephalosporins Penicillins (PCN) - Structure of penicillins o Beta-lactam ring – part of PCN structure o Break down the wall of the bacteria
o Some bacteria produce beta-lactamase – which destroys the PCN o Now developed beta-lactamase inhibitor o Combined with PCN to increase effectiveness o Basic penicillins - Introduced to kill Staphyloccus Inhibit bacterial cell wall synthesis Narrow-spectrum Examples: penicillin G Na/K, penicillin G procaine, penicillin V o Broad-spectrum penicillins Decreases chance of resistance Advantages & disadvantages Escherichia coli Salmonella Influenzae Penicillin G
o Least toxic and safest o Side/adverse effects : allergy to penicillin, rash superinfection (vaginitis), pain at injection site. Avoid arterial injection! o Teaching: Decrease effectiveness of oral contraceptive Penicillinase-resistant penicillins o Against most gram + (Bactericidal) o Used to treat S. aureas o Examples: dicloxacillin (Dynapen) Extended-spectrum penicillins o Antipseudomonal penicillins o Against gram – o Pseudomonas aeruginosa, Proteus , Klebsiella pneumoniae o Treat bone, joint, skin, soft tissue, respiratory tract, urinary tract infections o Examples: piperacillin (Pipracil), ticarcillin (Ticar), carbenicillin (Geopen) Beta-lactamase inhibitors o Are not given alone

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