抗生素英文课件精品Introductionto Antibacterial .ppt

Introduction to Antibacterial Therapy Clinically Relevant Microbiology and Pharmacology Edward L. Goodman, MD July 21, 2003 Rationale Antibiotic use (appropriate or not) leads to microbial resistance Resistance results in increased morbidity, mortality, and cost of healthcare Appropriate antimicrobial stewardship will prevent or slow the emergence of resistance among organisms (Clinical Infectious Diseases 1997; 25:584-99.) Antibiotics are used as “drugs of fear” (Kunin CM Annals 1973;79:555) Antibiotic Misuse Surveys reveal that: 25 - 33% of hospitalized patients receive antibiotics (Arch Intern Med 1997;157:1689-1694) 22 - 65% of antibiotic use in hospitalized patients is inappropriate (Infection Control 1985;6:226-230) Consequences of Misuse of Antibiotics Contagious RESISTANCE No equivalent downside to overuse of endoscopy, calcium channel blockers, etc. Morbidity - drug toxicity Mortality Cost Outline  Basic Clinical Bacteriology Categories of Antibiotics Pharmacology of Antibiotics Goodman’s Scheme for the Major Classes of Bacterial Pathogens Gram Positive Cocci Gram Negative Rods Fastidious GNR Anaerobes Gram Positive Cocci Gram stain: clusters Catalase pos = Staph Coag pos = S aureus Coag neg = variety of species Chains and pairs Catalase neg = streptococci Classify by hemolysis Type by specific CHO Staphylococcus aureus 95% produce penicillinase (beta lactamase) = penicillin resistant At PHD ~50% of SA are hetero (methicillin) resistant = MRSA Glycopeptide (vancomycin) intermediate (GISA) MIC 8-16 Eight nationwide (one at PHD) VRSA reported July 5, 2002 MMWR MIC 128 Evolution of Drug Resistance in S. aureus MSSA vs. MRSA Surgical Site Infections(1994 - 2000) Coagulase Negative Staph Many species – S. epidermidis most common Mostly methicillin resistant (65%) Often contaminants or colonizers – use specific criteria to distinguish Major cause of overuse of vancomycin Streptococci Beta hemolysis: Group A,B,C etc. Invasive – mimic staph in v