Antibiotics Overview and stewardship Flashcards
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Antibiotic Def
Antibacterial agent. Can be synthetic, semi synthetic and natural
Antiviral Def
Treats viral infections
Antifungal Def
Treats fungal infections
Antimicrobial Def
General term used to encompass drugs that target pathogens whether they be bacterial, viral or fungi
Selective Toxicity Outline
Drug administered targets pathogens. Only interacts with components in pathogen cells and have limited to no interactions with host (avoid damage and death in hosts)
Examples of things unique to pathogenic organisms (not present in hosts)
Cell walls, specific membrane antigens and certain DNA replication components
Empiric Treatment Outline
Treatment of an infection before data from the lab is obtained. General antimicrobials administered (Smart Start). Only factor taken into consideration is patient history
Targeted Therapy Outline
Treatment after lab reports are back. Treatment administered is specific to the pathogen and it’s particular susceptibilities
Prophylactic Therapy Outline
Administration of antimicrobials to prevent infection. Eg 30 minutes before surgery
Antibiotics Classifications
Antibiotic family, bactericidal vs bacteriostatic, narrow vs broad-spectrum and action mechanisms
Antibiotic Families
Beta-lactam, glycopeptide, aminoglycoside, quinolone, macrolide and tetracycline
Bacteriostatic Antibiotics Outline
Inhibits bacterial growth (doesn’t immediately kill - might kill as biproduct). Healthy patient immune defences kill pathogen
Bactericidal Outline
Kills bacteria, eliminating them from body. Used in immunocompromised individuals or for specific infections eg meningitis, endocartitis and blood infections
B-Lactams and glycopeptides Mechanism of Action
Bactericidal. Inhibits cell wall synthesis
Fluoroquinolones Mechanism of action
bactericidal. Inhibits DNA replication
Aminoglycosides Mechanisms Of Action
Bactericidal. Protein synthesis inhibition
Macrolides, lincosamides, streptogramins, chloramphenicol and oxazildilones Mecahnsism of action
Bacteriostatic. Protein synthesis inhibition
Polymyxins and lipoproteins Mechanisms of Action
Bactericidal. Binds to cell wall
Rifamycin’s Mechanisms of Action
Sometimes bactericidal, sometimes bacteriostatic. Inhibition of RNA polymerase (DNA dependent)
Tetracyclins Mechanism of action
Bacteriostatic. Protin synthesis inhibition
Trimethoprim and sulfonamides Mechanism of action
bacteriostatic. Folate synthesis inhibition
Narrow Spectrum Antibiotics Outline
Targets a specific type of organism. Can’t be used for empirical therapy but doesn’t damage human tissue. Eg penicillin G against gram positive cocci
Broad Spectrum Antibiotics Outline
Active against most types of bacteria. Can cause superinfection by overexposure but can be used in empirical therapy. Eg piperacillin-tazobactam treats gram positive cocci, gram negative bacillus, pseudomonas and anaerobic bacteria
Consequences of Incorrect Antibiotic Choices
Infection progression, resistance development and host cell damage
C difficile infection Outline
Spore forming bacteria in bowel. Infects colon resulting in diahorrea and fever and in extreme cases sepsis and death. Infection can be result of healthy microbiome disruption due to antibiotic course
4 main groups of bacteria according to antibiotic treatment
Gram positive, gram negative, anaerobes and atypical (small bacteria that lack a cell wall). Bacteria can be ultiple of these groups
Atypical Bacteria Outline
Chlamidya (intracellular pathogen (hard to culture)) and mycoplasma + ureaplasma (small bacteria with no cell wall
Narrow spectrum anti-gram positive agents
Penicillin and clindamycin
Broad Spectrum anti-gram positive agents
Cefalexin (beta-lactam), minocycline (tetracyclines) and erythromycin (macrolides)
Anti-Anaerobe Agents
Metronidazole
Anti-Atypical Agents
Tetracyclines, macrolides and quinolones.
Antibiotic attack outline
Disrupt bacterial essential structures/ processes; cell wall breach, gene expression interfrence and protein synthesis disruption
Cell wall breach Outline
Bactericidal. Denatures/destroys active agents of cell wall
Gene Expression Interference Outline
Rifamipicin inhibits RNA synthesis and ciproflaxin inbitis DNA replication
Susceptibility Testing Outline
In vitro tests predicting success/failure antibiotic in vivo. Test on both pathogen (antibiotic susceptibility and min inhibitory conc) and host (therapeutic effectiveness, allergies, ect) cells. Aids targeted therapy
2 Methods of Susceptibility Testing
Disk diffusion (semiquantative ~ qualative and Minimum Inhibitory Concentrations (MICs)
Disk Diffusion Outline
Whether pathogen is susceptible/ressistant. Inoculate agar plate with test organism, apply cellulose disks with standard amount of antibiotic (antibiotic diffuses into agar). Bigger the zone on the plate = the more resistant the pathogen
Minimum Inhibitory Concentration Outline
Lowest antibiotic conc required to stop bacterial growth (minimize toxic effects). Grow fixed quantity of bacteria in different concentrations of antibiotics (only 1 antibiotic tested at a time). Measure growth after 24 hrs (cloudier = more growth)
MIC Etest
Quantative, diffusion. 2 fold dilutions of highly concentrated antibiotic. Antibiotic concentrations are spread linearly along a strip determines efficacy of treatment. MIC = conc at point of lune where eclipse zone intersects
How does MIC help patients
If patient pathogen sample shows to respond to doses lower then standard dose we know that treatment will be effective. If a patient pathogen sample shows to respond only to doses higher then standard then different treatment is necessary (toxicity risk)
What uses a penicillin MIC
Viridans streptococcus
What uses a Gemiticin MIC
Kalesia pneumonia
Ideal Antibiotic Characteristics
Selective toxicity, bactericidal/static, spectrum, favourable pharmacokinetics (good bioavailability) , high TI and little/no resistance dev
Antimicrobial Stewardship Def
Timely and optimal selection of dose and duration of antimicrobial for the best clinical outcome (minimise toxicity and resistance dev). Careful monitoring of bacterial use
Antimicrobial Stewardship Outline
Patient outcome improvement (reduce morbidity and mortality), patient safety outcome (reduce antimicrobrial consumption), minimise ressistance risk and reduce cost (without reducing quality)
Empirical Treatment steps
Prescribe broad spectrum antibiotics (once bacterial infection is confirmed), take patient samples before treatment is administered (send to lab), document name, dosage and treatment duration and ensure antibiotics are taken 4 hrs (or 1 hr in severe sepsis) after prescription
Target Therapy Steps and Considerations
24-48 hrs after stopping, review lab results. Choice: stop antibiotics (no bacterial infection)/change route of admin/go on narrower range antibiotics/stay on current
Factors to consider moving from oral to IV
Clinical improvement (improving symptoms eg decreasing temp), oral route not compromised (GIT absorption), blood pressure + heart rate + breathing rate remain stable and if there’s no need for high drug conc in body tissues
Antibiotic Prophylaxis
2 types: surgical and medical. Prevent infections
Antibiotics Adverse Effects
Hypersensitivity (allergy), altered normal flora (eg C Diff), drug interactions, specific organ toxicity and antibiotic ressistan
Allergy Types Outline
Anaphylaxis (IgE, regulated), Urticaria (itchy raised skin, IgE regulated), Angioedema (rapid swelling, IgE regulated) and maculopapular rash
Is GIT irritation in response to penicillin an allergy
No
Altered Normal Flora Outline
Caused by use of broad spectrum antibiotics. Due to disruptions in normal flora opportunistic/super infections may arise. Eg C Diff (diahorrea)
Drug interactions outline
Drugs react to reduce the efficacy of eachother ( eg rifampicin and oral contraceptives). Others have negative consequences on patient health (eg vomiting) (eg ciprofloxacin and aminophylline)
Examples of tissue toxicities
rifampicin -> liver hepatitis, aminoglycasides -> nephrotoxicity and ototoxicity (auditory nerve)
