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pathopharm exam 4

CHAPTER 83

QuestionAnswer
Antimicrobials Used to treat infectious diseases190 million doses of antibiotics are given in hospitals each day Modern antimicrobials: 1930s and 1940s Significantly reduced morbidity and mortality from infection
Basic Principles of Antimicrobial Therapy Antibiotic •Strictly speaking, a chemical produced by one microbe that can harm other microbes
Basic Principles of Antimicrobial Therapy Antimicrobial agent •Any agent that can kill or suppress microorganisms
Selective Toxicity Toxic to microbes but harmless to host Differences in the cellular chemistry of mammals and microbes Disruption of bacterial protein synthesis and cell wall Inhibition of an enzyme unique to bacteria
Classification of Antimicrobial Drugs Various classification systems The two used for this textbook: •Classification by susceptible organism •Classification by mechanism of action
Classification of Antibiotics Drugs work on: •Cell wall synthesis •Cell membrane permeability •Protein synthesis (lethal) •Nonlethal inhibitors of protein synthesis •Synthesis of nucleic acids •Antimetabolites •Viral enzyme inhibitors
Bacteriocidal IS? Drugs are directly lethal to bacteria at clinically achievable concentrations
Bacteriostatic IS? Drugs can slow bacterial growth but do not cause cell death
Acquired Resistance to Antimicrobial Drugs? Over time, organisms develop resistance May have been highly responsive and then became less susceptible to one or more drugs
Organisms with Microbial Drug Resistance? Enterococcus faecium, Staphylococcus aureus, Enterobacter species, Klebsiella species, Pseudomonas aeruginosa, Acinetobacter baumannii, Clostridium difficile
Microbial Mechanisms of Drug Resistance Four basic actions •Decrease the concentration of a drug at its site of action •Inactivate a drug •Alter the structure of drug target molecules •Produce a drug antagonist
Mechanisms for Acquired Resistance Spontaneous mutation •Random changes in a microbe’s DNA •Resistance to one drugConjugation •Extrachromosomal DNA is transferred from one bacterium to another•Gram-negative bacteria •Multiple drug resistance
Antibiotic Use and Drug-Resistant Microbe Emergence How antibiotic use promotes resistance -Drugs make conditions favorable for overgrowth of microbes that have acquired mechanisms for resistance
Antibiotic Use and Drug-Resistant Microbe Emergence Antibiotics that promote resistance -Broad-spectrum agents do the most to facilitate the emergence of resistance
Antibiotic Use and Drug-Resistant Microbe Emergence The extent of antibiotic use affects resistance -The more that antibiotics are used, the faster drug-resistant organisms emerge
treatAntibiotic Use and Drug-Resistant Microbe Emergence Nosocomial infections•Healthcare–associated infections(HAI) Superinfection•New infection that appears during the course of treatment for a primary infection •Because superinfections are caused by drug-resistant microbes, they often are difficult to treat
Delaying Emergence of Drug Resistance Promote adherence to appropriate prescribing guidelines Reduce demand for antibiotics among healthy adults and parents of young children Emphasize adherence to prescribed antibiotic regimens
Public Health Action Plan to Combat Antimicrobial Resistance Focus Area I: Surveillance-MONITORING 02Focus Area II: Prevention and Control-IMPACT OF ANTIMICROBIAL 03Focus Area III: Research-KEY DRIVERS 04Focus Area IV: Product DevelopmenT-VACCINE
Selection of Antibiotics Identify organism-OSITVE OR NEGATIVE-BROAD-NARROW SPECTRUM Drug sensitivity of organism-HIGH CONCENTRATION OF DRUG Host factors-CROSS BBB Drug may be ruled out owing to: Allergy•Inability to penetrate site of infection•Patient variables
Empiric Therapy ASSESSMENT MD PAN-CULUTRE-CULTURE ANYTHING(WOUND, URINE,BLOOD), START ANTIBOTIC (BROAD-SPECTRUM) W/N 24HR-GET GRAIM-STAINED=POSITIVE OR NEGATIVE NARROW DRUG 48-72HR-KNOW ORGANISM NAROWDRUG SENSITIVE-HIGH/LOW %OF DRUG Antibiotic therapy for patients before causative organism is positively identified Drug selection based on: •Clinical evaluation •Knowledge of microbes most likely to have caused infection
Identifying the Infectious Organism MINIMUN INHIBITORY CNCENTRATION- MOST EFFECTIVE-INHIBIT BUT NOT KILLING THEM MINIMM BACERIACIADAL CONCENTRATION Match the drug with the bug Gram-stained preparation(QUICKEST WAY TO KNOW HE ORGANISM) DRUG SUSCEPTIBILITY-TEST SENSITIVITY OF ORGANISM W/ DRUG USE •Disk-diffusion test-KIRBY-BAUER(MEASURE ZONE) •Serial dilution- •Gradient diffusion
Host Factors MENINGITIS(BBB) ENDOCARDITIS(BACTERIA VEGETATION IN HEART DIFFICULT TO TREAT) ABSCESSES(POOR VASCULARITY AND THE PRESENCE OF PURULENT MATERIAL) Host defenses-PHAGOYITIC CELL-SUPPRES MICROBIAL GROWTH Site of infection-BLOOD FLOW-DRUG PRESENT AT INFECTION SITE Previous allergic reactions Genetic factors
Dosage Size and Duration SULFONOMIDES-KERNICTERUS-SEVERE NEUROLOGIC DISORDER IN NEWBORNS GENTAMICIN-LOSS OR HEARING IN INFANTS Antibiotic must be present: •At the site of infection •For a sufficient length of time Antibiotics must not be discontinued prematurely Teach patients to complete full prescription
Antibiotic Combinations STOP ABRUPTLY-REEMERGENCE POTENTIATIVE=SYNERGISTIC COMBINATION EFFECT IS GREATER THAN SUM OF INDIVIDUAL DRUG ADDITIVE-LIFE-SAVING EFFECTS-LOWER AMOUNT O DRUG ANTAGONISTIC-BACTERIOSTATIC(TETRA) W/ -CIDAL (PEN) Antimicrobial effects of antibiotic combinations- Additive, EFFECT OF2 DRUG =SUM OF 2 DRUGS potentiative,antagonistic Indications-Mixed infections, prevention of resistance, decreased toxicity, enhanced bacterial action Disadvantages: COST-SUPRINFEC
Prophylactic Use of Antimicrobials GIVEN TO PREVENT AN INFECTION- ABOUT 50% OARE GIVEN PROPHYLCTICALLY COMPLICATION=INCREASE RISK OF INFECTION WITH UTI Agents are given to prevent infection rather than to treat an established infection: •Surgery Bacterial endocarditis •Neutropenia •Other indications
Misuses of Antimicrobial Drugs Attempted treatment of viral infections Treatment of fever of unknown origin Improper dosage Treatment in the absence of adequate bacteriologic information Omission of surgical drainage
Monitoring of Antimicrobial Therapy RESOLUTION OF SIGN AND SYMPTOMS SERUM DRUG LEVEL Monitor clinical responses and laboratory resultsFrequency of monitoring should increase with severity of infectionClinical indicators of success•Reduction of fever, resolution of signs/symptoms related to the affected organSerum drug levels for toxicity
Which patient should receive prophylactic antibiotic therapy? A patient who is scheduled for a hysterectomy
A patient is prescribed an antibiotic to treat a urinary tract infection. What statement “I can stop the medication as soon as the symptoms have disappeared.”
Which statement about superinfections does the nurse identify as true?A.Superinfections are Superinfection is defined as a new infection that appears during the course of treatment for a primary infection.
Created by: Seka_nurse
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