Y4 - Prudent Antimicrobial Prescribing Flashcards
Which antibiotics inhibit cell wall synthesis?
Penicillins Cephalosporins Carbapenems Daptomycin Glycopeptides
What antibiotic inhibits DNA synthesis?
Fluoroquinolones
What antibiotic inhibits RNA synthesis?
Rifampicin
What antibiotics inhibit protein synthesis?
Macrolides Chloramphenicol Tetracycline Aminoglycosides Oxazolidonones
What antibiotics inhibit folic acid synthesis?
Sulfonamides
Trimethoprim
True or false:
Bactericidals work faster than bacteriostatics
True
Which antibiotics are bactericidal?
Beta-lactams Glycopeptides Fluoroquinolones Cephalopsorins Daptomycin Aminoglycosides
Which drugs are bacteriostatic?
Tetracyclines Clindamycin Sulfonamides Chloramphenicol Linezolid
Which drugs are intermediate (can be bactericidal or bacteriostatic)?
Macrolides
What antibiotics are beta-lactams?
Penicillins, carbapenems, cephalosporins
What is the structure of beta-lactams and how do they work?
Contain a beta-lactam ring which inhibits formation of peptidoglycan cross links in the bacterial cell wall
What must you do before using carbapenems?
Seek microbiology advise
Give examples of antibiotics which are glycopeptides
Vancomycin and teicoplanin
Bactericidals should always be used for what group of patients?
Immunocompromised patients
What are the mechanisms of bacterial resistance to antibiotics?
- Bacteria acquire genes encoding enzymes to inactivate antibiotics, e.g. B-lactamases
- Bacteria finds alternative metabolic pathway, e.g. trimethoprim
- Alteration of the target site so antibiotic is no longer able to bind
- Decreased permeability via porin channels in the cell wall
- Antibiotic is removed from the bacteria via an efflux pump, e.g. tetracyclines
What is the difference between penicillin V (phenoxymethylpenicillin) and penicillin G (benzylpenicillin)?
Penicillin G is IV only
Penicillin V is oral only
What is the coverage with penicillin V/benzylpenicillin?
Streptococci
Enterococci (faecalis & faecium)
Moderate coverage of anaerobes
What are coliforms?
Gut bacteria, e.g. E. coli
Give examples of atypical bacteria
Legionella
Chlamydia
Mycoplasma pneumoniae
Myobacterium tuberculosis
Why are bacteria classed as atypical?
They don’t gram stain
What is coagulase negative staph?
Any staph that is not staph aureus
What is the coverage of flucloxacillin?
Staph, strep
Best for staph aureus
What is the coverage of amoxicillin?
Strep
Enterococcus faecalis
Moderate anaerobe, coliform and respiratory (e.g. H. influenzae, Moraxella catarrhalis) cover
What is the coverage of co-amoxiclav?
Staph Strep Enterococcus faecalis Anaerobes Coliforms Respiratory
What is co-amoxiclav?
Amoxicillin + clavulanic acid (Beta-lactamase inhibitor)
Helps overcome beta-lactam resistance
What are the broad spectrum penicillins?
Piperacillin/tazobactam
Cover staph, strep, enterococcus faecalis, anaerobes, coliforms, respiratory pathogens and pseudomonas aeruginosa
What are the two carbapenems?
Ertapenem and meropenem
What is the coverage of the carbapenems?
Ertapenem and meropenem cover staph, strep, Ef, anaerobes, coliforms, respiratory, ESBL
Meropenem also covers pseudomonas aeruginosa
What are the cephalosporins?
Cefalaxine (1st gen) Cefuroxime (2nd gen) Cefotaxime & ceftriaxone (3rd gen) Ceftaroline (5th gen) Ceftazidime/avibactam
What is the coverage of 1st to 5th generation cephalosporins and what trend does coverage follow as the generations become later?
All cover staph, strep and coliforms,
After 2nd generation, all moderately cover anaerobes and cover respiratory well
3rd and 5th generation moderately cover ESBL
5th generation covers MRSA
What are the tetracyclines?
Tetracycline
Doxycycline
What is the coverage of doxycycline?
MRSA Staph Respiratory Atypicals Moderately covers ESBL, strep, anaerobes
What is the coverage of trimethoprim?
Moderately covers MRSA, staph, strep, Ef, coliforms, respiratory
What is the coverage of co-trimoxazole?
MRSA, staph, coliforms
Moderately covers strep, Ef, respiratory
What is co-trimoxazole?
Sulfamethoxazole & trimethoprim
What are the macrolides?
Azithromycin
Clarithromycin
Erythromycin
What is the coverage of erythromycin?
Atypicals
Moderately staph, strep, anaerobes, resp
What is the coverage of azithromycin & clarithromycin?
Staph, respiratory, atypicals
Moderately strep, anaerobes
What is the coverage of clindamycin?
Staph, strep, anaerobes
What antibiotics are used for gram negative cover?
Ciprofloxacin/ofloxacin Levofloxacin/moxifloxacin Gentamicin/tobramycin/amikacin Aztreonam Fosfomycin
What is the coverage of ciprofloxacin/ofloxacin?
Coliforms, respiratory, pseudomonas, atypicals
Moderately staph, strep, Ef, ESBL
What is the coverage of levofloxacin/moxifloxacin?
Staph, strep, coliforms, resp, pseudomonas, atypicals
Moderately Ef, ESBL
What is the coverage of the aminoglycosides?
MRSA, staph, coliforms, resp, pseudomonas
Moderately ESBL
What is the coverage of aztreonam?
Coliforms, resp, pseudomonas
What is the coverage of fosfomycin?
MRSA, staph, coliforms, ESBL
Moderately strep
What antibiotics are good for gram positive cover?
Vancomycin and teicoplanin
Sodium fusidate
What is the coverage of the glycopeptides?
All gram positives (MRSA, staph, strep, Ef, anaerobes)
What is the coverage of sodium fusidate?
All gram positives (MRSA, staph, Ef, anaerobes, only moderately strep)
What is the coverage of metronidazole?
Anaerobes
What is the coverage of nitrofurantoin?
MRSA, staph, strep, Ef, coliforms, ESBL
What is the issue with nitrofurantoin?
Poor tissue penetration results in treatment failure in anything other than a lower UTI
NOT suitable for urosepsis/pyelonephritis
What is the coverage of rifampicin?
MRSA, staph, strep, resp, atypicals
Moderately Ef
What is the coverage of chloramphenicol?
Everything apart from pseudomonas
Which antibiotics are known for their nephrotoxicity?
Vancomycin, teicoplanin, gentamicin
How do you treat community acquired pneumonia (CURB 0-1)?
Admission to hospital probably unnecessary
Amoxicillin
or
Doxycycline
How do you treat community acquired pneumonia (CURB 2)?
Amoxicillin PLUS doxycycline
Consider admission to hospital
How do you treat community acquired pneumonia (CURB 3-5)?
Admit to hospital
Amoxicillin PLUS doxycycline OR levofloxacin
Vancomycin if MRSA suspected
What is trimethoprim used for mostly?
1st line for UTIs
What is co-trimoxazole used for?
Treating staph skin infections
What is often used as an alternative for those with penicillin allergy?
Clarithromycin
What are the issues with the macrolides?
Prolong QT interval
DDIs common
Prolonged use can cause sudden cardiac death
What are the ADRs assoc with quinolones?
Inhibit liver enzymes, DDIs, Achilles tendinitis, prolong QT interval and reduce seizure threshold - therefore must be avoided in those with epilepsy, alcoholics, recent head injury
How can quinolones affect older people?
May cause them to become drowsy and disorientated
What sort of toxicity can gentamicin cause?
Ototoxicity and renal toxicity
Ototoxicity often manifests as balance issues
What are vancomycin/teicoplanin useful for?
Orally only covers stuff in bowel (e.g. C. diff)
IV covers staph and strep
What are the issues with linezolid?
Supresses bone marrow
Cannot be used in conjunction with antidepressants
Can cause optic neuritis
Do not use for more the 28d
What is sodium fusidate used for and what is the issue with it?
Impetigo
Do not use on own for long periods of time as staph become v. resistant to it
What antibiotic must not be taken with alcohol?
Metronidazole
Can cause facial flushing and hypotension
What can rifampicin be used for?
TB
Also aids penetration of other antibiotics in prosthetic infection by interrupting bacteria biofilm
What are the issues with rifampicin?
Interacts with rivaroxaban and warfarin etc.
Induces hepatic enzymes
What is chloramphenicol used for?
Meningitis (crosses BBB when meninges inflamed)
What is the issue with chloramphenicol?
Can cause aplastic anaemia
What is community acquired pneumonia?
Pneumonia acquired outside the hospital
What scoring system is used to assess the prognosis associated with pneumonia?
CURB 65 Confusion RR 30+ Urea >7mmol/L BP diastolic of 60 or less, or systolic of 90 or less 65y+
What mortalities are associated with:
- CURB65 0/1
- CURB65 2
- CURB65 3-5
0-1: <3%
2: 3-15%
3-5: >15%
What CURB65 scores should be admitted to hospital?
0-1 - home based care
2 or more consider hospital care
3 or more may consider ITU care
When should you offer microbiological tests for community acquired pneumonia?
Moderate/high severity CAP only
What tests should be done for community acquired pneumonia?
Blood and sputum cultures
Consider pneumococcal and legionella urinary antigen tests
XRay to diagnose
What two organisms cause most skin and soft tissue infections?
Staph or strep
What is the mainstay antibiotic for skin and soft tissue infections?
Flucloxacillin
Clarithromycin if allergic
Vancomycin if MRSA
What antibiotic is best to cover bites?
Co-amoxiclav (as it covers anaerobic gram negatives as transferred from saliva)
How do you treat uncomplicated UTI?
Trimethoprim
200mg BD
3 days for women
7 days for men
How do you treat uncomplicated UTI in pregnancy?
Nitrofurantoin (avoid in 3rd trimester)
7 days
How do you treat urosepsis?
Gentamicin
Aztreonam if kidney problems