ANTIBACTERIAL AGENTS
Are prescribed to combat disease producing microorganisms (pathogens) Used interchangeably with antimicrobials and antibiotics Examples: Penicillins Cephalosporins Macrolides Tetracyclines Aminoglycosides Fluoroquinolones BACTERIOSTATIC Inhibit the growth of bacteria Tetracycline and sulphonamides BACTERICIDAL Kills bacteria Penicillins and cephalosporins BACTERIA Single cell organisms lacking a true nucleus and nuclear membrane Bacillus rod shape Cocci- spherical Gram positive-retain purple stain Gram negative-not stained Pharmacokinetics Must penetrate bacterial cell wall and have an affinity to the binding sites on the bacterial cell Steady state of the antibacterial drug occurs after the fourth to fifth half lives Eliminated through the urine after the 7th half life Pharmacodynamics Attain bactericidal effect if within or above the minimum effective concentration (MEC) General adverse reaction to antibacterial drugs: Allergy/hypersensitivity Superinfection occurrence of a secondary infection when the natural flora of the body is disturbed Organ toxicity nephrotoxicity and hepatotoxicity are most common NARROW SPECTRUM ANTIBIOTICS Effective against one type of organism Penicillin and erythromycin against gram positive BROAD SPECTRUM Effective against narrow and broad spectrum antibiotic Used when offending organism is not identified Tetracyclines and cephalosporins
MECHANISM OF ANTIBACTERIAL ACTION 1. Inhibition of bacterial wall synthesis 2. Alteration of membrane permeability 3. Inhibition of protein synthesis 4. Inhibition of the synthesis of bacterial RNA and DNA 5. Interference with metabolism within the cell ACTION Inhibition of cell wall synthesis EFFECT Bactericidal effect Enzyme breakdown of cell wall Inhibition of enzymes in synthesis of cell wall Bacteriostatic or bactericidal effect Membrane permeability increase Interferes with protein synthesis w/o affecting the normal cells Interferes with steps of metabolism within the cell DRUGS Penicillin Cephalosporins Bacitracin Vancomycin Amphotericin B
Alteration in membrane permeability
Nystatin Polymyxin Colistin
Inhibition of protein synthesis
Aminoglycosides Tetracyclines Erythromycin lincomycin Sulfonamides Trimetoprim Isoniazid Nalidixic acid Rifampin
Interference with cellular metabolism
I.
Penicillins: beta-latam ring that interferes with cell wall synthesis
a. Natural antibacterial agent obtained from the mold genus Penicillium Food interferes with absorption Beta lactam antibiotics Beta lactamases- produced by bacteria and inactivates penicillin Antibiotic combinations additive equal to the sum of the effects of both antibiotics potentiative one antibiotic potentiates the effect of the other, increasing its effectiveness antagonistic combination of a bactericidal and bacteriostatic, which reduces the desired effect Basic penicillins Penicillin G procaine Penicillin G benzathine Penicillin G sodium Penicillin V potassium Broad spectrum penicillins (aminopenicillins) used for gram positive and negative organisms; more costly than basic penicillins Amoxicillin (Amoxil) inhibits bacterial cell wall synthesis
administration route: PO, without food conditions treated: respiratory tract disorders urinary tract disorders otitis media sinusitis contraindications: allergies severe renal disorders drug interactions: effects when taken with erythromycin and tetracycline probenacidserum antibacterial levels side effects/adverse reactions: N/V/D rash edema stomatitis
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Penicillinase resistant penicillins (Antistaphylococcal penicillins) used to treat penicillinase producing S. aureus Cloxacillin (Cloxapen) and dicloxacillin ( Dynapen)-oral prep o PO antibiotic; not effective against gram (-) organisms and less effective against gram (+)
e.
Beta Lactamase Inhibitors broad spectrum antibiotic combined with a beta lactamase (enzyme inhibitor/clavulanic acid) to inhibit bacterial beta-lactamases Amoxicillin-clavulanate (Augmentin) combination of amoxicillin and clauvanic acid, which intensifies the drug o fights off the beta lactamase enzyme that attack the penicillin
f.
Common side effects and adverse reactions: o Hypersensitivity o Superinfection o Nausea o Vomiting o Diarrhea o Rash o Anaphylactic reaction
II.
Cephalosporins: bactericidal antibiotic that inhibits cell wall synthesis
a. First discovered in seawater-fungus called cephalosporium acremonium Effective against gram (+) and gram (-) bacteria Have a beta lactam structure Cause bacteria cell lysis 4 generations of cephalosporins: resistance and severity of the infection increases as the generation increases Generation Activity effective against gram positive streptococci and staphylococci Gram negative ( E.Coli ,Klebsiella, Salmonella and Shigella) Broader spectrum against gram negative ( Haemophilus influenzae, Neisseria Gonorrhea, neisseria meningitidis) Effective against gram negative (pseudomonas aeruginosa, Acinetobacter) Less effective against gram positive bacteria Broader gram positive coverage than the third generation Drugs Cephalexin (Keflex) Cefazolin sodium ( Ancef, kefzol)
1st 2nd 3rd 4th
administration route: Cefazolin (1st generation): IM or IV Cefaclor (2nd generation): PO
Cefaclor (ceclor) Cefuroxime (Ceftin, Zinacef) Cefoxitin sodium ( Mefoxin) Ceftriaxone (Rocephin) Cefotaxime (Claforan) Ceftazidime (Vantin) Cefepime ( Maxipime)
Cefazolin (Ancef) and Cefaclor (Ceclor) bactericidal antibiotics that inhibit cell wall synthesis
conditions treated: both treat urinary, respiratory and skin infections bone, joint and genital infections endocarditis ear infection ampicillin resistant strains certain gram (-) organisms and gram (+) strains contraindications: drug interactions: effect when given with probenacid effect when given with tetracyclines and erythromycin side effects/adverse reactions: N/V/D, rash anorexia, vomiting, abdominal cramps fever seizures (w/ doses) pruritis headaches vertigo weakness
allergies to cephalosporins
Cefuroxime (Ceftin) given PO to treat meningitis, septicemia with cardiothoracic procedures and surgical prophylaxis b. Common side effects and adverse reactions: GI disturbances ( Nausea, vomiting, diarrhea) Increased bleeding Nephrotoxicity Drug interactions When taken with alcohol flushing ,dizziness, headache, nausea and vomiting, muscular cramps When taken with uricocosuric drugs, decreased excretion CLIENT TEACHING Report signs of superinfection- mouth ulcers, discharge from genital or anal area Ingest buttermilk or yogurt to prevent superinfection of instestinal flora Take complete course of medication even if infection have ceased Observe for hypersensitivity reaction
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