Antimicrobial Chemotherapy 2 COPY Flashcards
What are some commonly used B-lactams (penicillins)?
Benzyl penicillin
Amoxicillin, ampicillin
Co-amoxicaly
Flucloxacillin
Piperacillin
Imipenem, meropenum
What does benzyl penicillin act against?
Gram positive bacteria
What does amoxicillin and ampicillin act against?
Gram negative bacteria
What does co-amoxicaly act against?
B-lactamase producing coliforms
What is flucloxacillin the best treatment for?
Staphyloccocal infection
What does piperacillin treat?
Extended gram negative coverage
What does imipenem and meropenem treat?
Most bacteria, including anaerobes
What is a class of B-lactams other than penicillin?
Cephalosporins
How does the activity of cephalosporins change against gram negative and positve bacteria through the generations?
Activity against gram negative bacteria increases
Activity against gram positive bacteria decreases
What are the 3 generations of cephalosporins?
1) Cephradine
2) Cefluoxime
3) Ceftrixone
What are some commonly used agents other than B-lactams?
Aminoglycosides
Glycopeptides
Macrolides
Quinolones
How are aminoglycosides administered?
Only parenterally
What are aminoglycosides useful against?
Gram negative bacteria
What gram positive bacteria is sensitive to aminoglycosides?
Only staphylococci
What is an example of an aminoglycoside?
Gentamicin
How are glycopeptides administered?
Parenteral use only
What are glycopeptides active against?
Gram positive bacteria (anaerobic and aerobic)
What are examples of glycopeptides?
Vancomycin
Teicoplanin
What are macrolides mainly active against?
Gram positive bacteria
When are macrolides often used?
As an alternative to penicillin for people who are allergic
What are examples of macrolides?
Clarithromycin
Erythromycin
Azithromycin
What are quinolones active against?
Nearly all gram negative bacteria
What are some miscellaneous commonly used agents?
Metranidazole
Fusidic acid
Co-trimoxazole
Tetracyclines
Clindamycin
What is metronidazole used against?
Anaerobes, both gram positive and negative
What is fusidic acid used against?
Staphyloccocus
What is co-trimoxazole?
A combination of trimethoprim and sulphamethoxazole
What kinds of infection are tetracyclines useful for?
Some genetial tract and respiratory tract infections
What is clindamycin useful against?
Gram positive and anaerobes
What are some commonly used new agents?
Linezolid
Daptomycin
What is linezolid used against?
MRSA
What is daptomycin active against?
Only gram positive bacteria
What is daptomycin useful for the treatment of?
Serious MRSA infections
What is a positive of linezolid compaired to glycopeptides?
It can be given orally
What are some agents that are only used for urinary tract infections?
Nalidixic acid
Nitrofurantoin
What is nalidixic acid active against?
Only against gram negative aerobes (coliform) bacteria
What is nitrofurantoin effective against?
Most gram negative bacteria
Some gram positive bacteria
What are most antimicrobials associated with?
Adverse reactions
What does the incidences of adverse reactions depend on?
Dose of therapy
Duration of therapy
What are some different kinds of adverse reactions?
Allergic reaction
Immediate hypersensitivity
Delayed hypersensitivity
Gastrointestinal side effects
Thrush
Liver toxicity
Renal toxicity
Neurological toxicity
Haematological toxicity
What is an example of immediate hypersensitivity?
Anaphylactic shock
What are some common gastrointestinal side effects?
Nausea
Vomiting
Diarrhoea
What is thrush?
Surpress normal flora in parts of the body resulting in overgrowth of resistant organisms
What are examples of liver toxicity?
Transient elevators of liver enzymes
Severe hepatitis
What is haematological toxicity?
Toxic effects on the bone marrow resulting in selective depression of one cell line (neutropenia) or unselective depression of all bone marrow elements (pancytopenia)
What is neutropenia?
Selective depression of one cell line of bone marrow
What is pancytopenia?
Unselective depression of all bone marrow elements
How can adverse side reactions be minimised?
Antimicrobials should only be used when indicated and in the minimum dose and duration to achieve efficacy
Who should adverse reactions be reported to?
Commitee on safety of medicines
What has been set up on each health board to monitor antimicrobial prescribing and develop policy?
Antimicrobial management teams
What are factors that should be considered when deciding which antimicrobial agents to use are?
Age
Renal function
Liver function
Pregnancy
What is prophylaxis?
Administration of antimicrobials to prevent the future occurence of infection
What should happen when the organism causing infection is unknown?
Empirical antimicrobial therapy (broad spectrum) should be commenced if urgent treatment is required
What should we consider when deciding which drug to use?
Spectrum of antimicrobial agent
Monotherapy v combination
Penetration to site of infection
Monitoring
Dose and duration of therapy
What can mixing drugs do?
Cover mixed infections by more than one organism
Could have enhanced effect together
Minimise the development of resistant strains
Why is monitoring done?
Difference between a therapeutic and toxic dose is small in a drug with a low therapeutic index
What are the 3 possible outcomes when we use antimicrobials in combination?
Anatagonistic and combined effect is less than the sum of their individual contribution
Synergistic and their combined effect is greater than the sum of their individial contribution
Their effects are addictive
What is a cidal antibiotic (bactericidal)?
One that kills bacteria without reliance on the patient’s immune system to help
What is a static antibiotic (bacteriostatic)?
One that prevents the organism multiplying but it is the patient’s immune system which kills off the bacteria
What is the combination of two cidal or two static drugs?
Synergistic or addictive
What is the combination of one static and one cidal drug?
Antagonistic
What is the role of the laboratory, and of medical microbiologists?
Give advice on the choice of antimicrobial
What are the 2 reasons for monitoring the serum levels of an antimicrobial?
Ensure that therapeutic levels have been achieved
Ensure that levels are not so high to be toxic
What does the serum levels being the same as the tissue depend on?
Antimicrobial’s ability to penetrate
What is serum levels?
Amount of medication in your blood
What is the simplest way to measure the minimum inhibitory concentration (MIC) of an antibiotic agent?
E-test
What is an E-test?
Commercially available paper strip which has a gradient of antibiotic concentration from the point where the organism intersects the strip
What are methods of measuring the minimum inhibitory concentration (MIC) an an antibiotic agent other than an E-test?
Automated, which labs use, where growth of individual isolates are measured in the presence of different concentrations of each antibiotic and MIC is calculated
What does in vitro laboratory test give?
A prediction whether the infection is likely to be cured by the antibiotic in question
What are factors that influence the outcome of using antibiotics?
Route of administration
Dosing schedule
Penetration of antibiotic to target site
Interaction with other drugs
