Antimicrobial Agents Chemotherapy Antimicrobial agents Antibiotics Semisynthetic antibiotics The Discovery of Penicillin Ideal Qualities of an Antimicrobial Agent Kill or inhibit the growth of pathogens Cause no damage to the host Cause no allergic reaction in the host Be stable when stored Remain in specific tissues in the body long enough to be effective Kill the pathogen before they mutate and become resistant to it How Antimicrobial Agents Work Inhibition of cell wall synthesis Damage to cell membranes Inhibition of nucleic acid synthesis Inhibition of protein synthesis Inhibition of enzyme activity Antibacterial Agents Bacteriostatic Bacteriocidal Narrow spectrum antibiotics Broad spectrum antibiotics Multi-drug therapy Synergism Antagonism Antifungal Agents Potentially more toxic to the patient Mechanisms Binding cell membrane sterols Interfering with sterol synthesis Blocking mitosis Blocking nucleic acid synthesis Antifungal Agents Antiprotozoal Agents Antiviral Agents How Bacteria Become Resistant to Drugs Intrinsic resistance Acquired resistance Mechanisms by Which Bacteria Become Resistant Beta-Lactamases Beta-lactam ring Penicillinases Cephalosporinases Beta-lactamase inhibitors Clavulanic acid + amoxicillin (Augmentin) Sublactam + ampicillin (Unasyn) Tazobactam + pipericillin (Zosyn) Superbugs Methicillin-resistant Staphylococcus aureus (MRSA) and S. epidermidis (MRSE) Vancomycin-resistant Enterococcus spp. Multi-drug resistant Mycobacterium tuberculosis Multi-drug resistant Pseudomonas spp., Salmonella spp., Shigella spp., and Neisseria gonorrhoeae Beta-lactamase-producing Streptococcus pneumoniae and Haemophilus influenza What Can be Done to Prevent Drug Resistance? Educate health professional, patients Don?t proscribe a drug unnecessarily Patients with a sick child Physicians Use inexpensive, narrow spectrum antibiotics whenever possible Take the antibiotics as directed Take the full course of treatment What Can be Done to Prevent Drug Resistance? Destroy excess antimicrobial (don?t save for later) Don?t use antibiotics prophylactically (unless directed to) Isolate patients with multi-drug resistant pathogens Practice good infection prevention and control Empirical Therapy Initiating treatment before lab results are available Educated guess Antibiogram (?pocket chart?) Empirical Therapy Considerations Allergies? Age? Pregnancy? Inpatient or outpatient? Hospital formulary? Site of infection? Other medications onboard? Additional medical problems? Immunocompromised? Cost? Undesirable Effects of Antimicrobials Selecting for resistant organisms Development of allergies Toxicity Chloramphenicol (aplastic anemia) Streptomycin (deafness) Hepato-, nephrotoxcicity Destruction of normal flora Superinfection Clostridium difficile Candida albicans
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