Antimicrobial Therapy Flashcards
What is the most common cause of GI infection in the UK?
Campylobacter
What is the standard treatment of sepsis
Co-amoxiclav + gentamicin (broad spectrum)
What are platelet levels in sepsis?
Low
What scan would you use to see an (GI) abscess?
CT
How would you treat a large GI abscess e.g. from appendicitis?
1) Washout and drainage of pus and dead tissue in theatre
2) Send pus to lab to culture bacteria e.g. E.coli
3) Treat with antibiotics e.g. co-amoxiclav
What bacteria is a common cause of intra-abdominal sepsis?
E.coli
What infection has a 100% mortality if untreated?
Endocarditis
How do you treat with antibiotics?
Start with broad spectrum/empirical antibiotics and then narrow down the therapy after getting microbiology results
What should you write on a drug chart when giving an antibiotic?
Indication and stop date
How do you give antibiotics as part of surgical prophylaxis?
Only a few doses before, maybe during if long surgery and 48h after
What is a common antibiotic-associated infection?
C.difficile
What are the 3 possible results of antimicrobial susceptibility disc testing?
1) R = resistant
2) I = intermediate but mainly resistant
3) S = sensitive
What is MIC?
Minimum inhibitory concentration = the lowest concentration of the antibiotic being tested that inhibits growth of the organism in a broth
What is MBC?
Minimum bactericidal concentration = the lowest concentration of the antibiotic that kills the organism
What are the 7 main classes of antibiotics?
1) Beta lactams (penicillins, cephalosporins and carbapenems)
2) Macrolides
3) Tetracyclines
4) Trimethoprim and co-trimoxazole
5) Quinolones
6) Aminoglycosides
7) Glycopeptides
Why are cephalosporins used less now?
They are implicated in C difficile
What is the first line antibiotic in chest infection (gram negative)?
Amoxicillin
Which antibiotics are frequently given for UTIs?
- Cefalexin (cephalosporin)
- Trimethoprim
What type of bacteria is flucloxacillin commonly used again?
Staphylococcus
What are the 3 macrolides?
1) Clarithromycin
2) Erythromycin
3) Azithromycin
What are macrolides esp. clarithromycin used for?
Used in penicillin-allergic patients against gram positive bacteria (staphylococci or streptococci) in e.g. SSTIs, throat infections, atypical pneumonia
When are the tetracyclines used e.g. doxycycline?
- Penicillin allergic patients who suffer side effects with macrolides
- Broad spectrum
- Respiratory tract and SSTIs
- Atypical CAP
- Resistance is common
What is co-trimoxazole used for?
- Infections in immunocompromised patients e.g. prophylaxis and treatment of PJP
What are quinolones (ciprofloxacin) used for?
- Against gram-negative bacteria
- Newer ones more useful against gram-negative e.g. S.pneumoniae
What is the most common aminoglycoside?
Gentamicin
What are aminoglycosides used for?
- Gram-negative bacteria
- Useful synergy with penicillins against streptococci
- Serious sepsis (quick acting)
- V potent when organism is sensitive
- Often given with beta-lactam to extend spectrum of cover
What is the problem with aminoglycosides?
- They can cause vestibulocochlear nerve and renal toxicity (nephrotoxic and neurotoxic) which can lead to hearing loss
- Serum levels must be measured
What are glycopeptides used for?
- ONLY gram-positive bacteria (staphylococcus, streptococcus, enterococcus)
- MRSA
- Sometimes used when patients are penicillin allergic
What are the two glycopeptides?
1) Vancomycin
2) Teicoplanin (less toxic)
What is vancomycin used for and what has to be done with it?
- Broad spectrum against gram-positive
- Used to treat C. diff
- Potentially nephrotoxic, need to measure blood levels
What is metronidazole used for?
- Active against anaerobes
- e.g. intra-abdominal sepsis where may have been leakage of gut contents
- Amoebae
- Trichomonas vaginalis
What is linezolid used for?
- Gram positive bacteria
- MRSA
- Glycopeptide-resistant enterococci (VRE)
What is chloramphenicol used for?
- Bone marrow toxicity so only used occasionally for meningitis and topical treatment of eye infections
- e.g. for v penicillin allergic pt with unknown cause bacterial meningitis
What is penicillin used for?
- Serious streptococcus
- Meningococcal meningitis
What is ceftriaxone used for?
Blind therapy for bacterial meningitis
What two beta-lactams are effective against pseudomonas?
- Piperacillin-tazobactam
- Ceftazidime
What is fosfomycin used for?
Multi-resistant gram-negative infections
What is fidaxomicin used for?
Elected cases of severe or recurrent C.difficile diarrhoea cases
What is colistin used for?
Multiple or pan resistant gram-negative infections
What is daptomycin used for?
Gram-positive bacteria (to replace glycopeptide - similar activity)
What is fusidic acid used for?
- Staphylococcal infections only
- Topical
What is bad about erythromycin?
GI side effects
What is rifampicin used for?
- Gram-positive bacteria
- Prosthetic valve endocarditis and other prosthesis infections - typically combined with anti-staph agent e.g. vancomycin
- Part of first line TB regimen
What are coliforms (problem resistance bacteria)?
Klebsiella, enterobacter
Where are yeasts (candida e.g. albicans) typically found in serious infections?
Urinary tract, intra-abdominal, bloodstream
Where are moulds (aspergillus) typically found?
Sinusitis, pulmonary, disseminated, transplant, haemato-oncology
What is the main antifungal given orally for systemic infection?
Fluconazole (but resistant problems)
What is the main antifungal given for serious fungal infection with the most predictable broad spectrum cover>
(Liposomal) amphotericin B
