Microbiology 21: Antimicrobial Agents 2 Flashcards
What are the 2 common organisms that cause skin infections such as Impetigo or Cellulitis ?
What antibiotic is commonly used to treat these ?
Staph Aureus
Beta haemolytic streptococcus (Strept. pyogenes)
Flucloxacilin
Which 2 toxicities must you consider when giving aminoglycosides ?
Ototoxicity
Nephrotoxicity
Which antibiotic is common used to treat mild typical CAP ?
Amoxicillin
Usually due to pneumococcus and Haemophilus
What is the most common causative organism of CAP ?
Streptococcus pneumonia
List 3 atypical organisms that cause CAP ?
Legionella, Mycoplasma, Chlamydia
Usually associated with severe CAP
Which antibiotic is commonly used to treat Bacterial meningitis ?
What can you add to the Tx and why?
Ceftriaxone
Can add Amoxicillin if Listeria is likely (groups at risk of this are < 3-month-old babies, > 65 year olds, pregnant women)
Why is ceftriaxone not given to children under 3 months of age ?
Causes biliary sludging (displaces bilirubin from albumin)
Therefore give cefotaxime AND amoxicillin (the latter for listeria cover)
List 2 sequele you worry about after a streptococcal infection ?
Glomerulonepohritis
Rheumatic fever
Hence why it needs to be treated for 10 days
Which antibiotics are commonly used to treat HAP ? (4)
- Cephalosporin
- Ciprofloxacin
- Tazocin
- If MRSA, consider addition of vancomycin
Which antibiotic is commonly used to treat simple cystitis in the community setting ?
Trimethoprim (3 days)
Which antibiotic is commonly used to treat Hospital acquired UTI ? (NB most common type of HAI)
Cephalexin or Co-amoxiclav
Which antibiotic is common used to treat atypical CAP ?
Macrolide (Erythromycin/Clarythromycin) + Tetracycline (doxycycline)
Which antibiotic is common used to treat severe typical CAP ?
Penicillin (Co-amoxiclav) + Macrolide (Clarithromycin)
Which antibiotics are used to treat HAP due to aspiration ?
Cefuroxime + metronidazole
Which antibiotics are used to treat atypical CAP with confirmed legionella ?
Rifampicin + Macrolide (Erythromycin, Clarythromycin)
Which antibiotics could be used to treat HAP with Pseudomonass spp. ?
Tazocin (pippericilin + Tazobactam) or ciprofloxacin + gentamicin
What is the treatment for primary Syphilis ?
IM benzyl penicillin
What is the treatment for N.Ghonorrhoea ?
IM ceftriaxone
What is the treatment for Chlamydia ?
Doxycycline (or azithromycin)
What is the treatment for BV ?
Metronidazole
What is the treatment for Trichomoniasis ?
Metronidazole
What is the treatment of bacterial meningitis due to N.meningitidis or S.Pneumonia ?
Ceftriaxone + Prednisolone
What is the treatment of bacterial meningitis due to Listeria ?
Ceftriaxone + Ampicillin + Prednisolone
name two methods of antibiotic susceptibility testing
MIC (minimum inhibitory concentration) - this is the least amount of drug required to inhibit the growth of the organism in a culture
Agar disc diffusion method
when is IV to PO switching of antibiotics usually recommended
What is an exception to this?
if the patient has stabilised after 48 hrs of IV treatment
In CNS infections and severe infections such as osteomyelitis and endocarditis, you may NOT switch to PO
describe the 3 main patterns of antibiotic activity
TYPE 1: concentration dependent killing and prolonged persistent effects eg aminoglycosides
TYPE 2: time dependent killing and minimal persistent effects eg carbapenems, penicillins
TYPE 3: time dependent killing and moderate to prolonged persistent effects
what are the lengths of treatment for the following:
- N meningitidis meningitis
- Acute osteomyelitis
- bacterial endocarditis
- group A strep pharyngitis
- simple cystitis
1 - 7 days
2 - 6 weeks
3 - 4-6 weeks
4 - 10 days
5 - 3 days
antibiotic or choices for:
1 - pharyngitis
2 - mild CAP
3 - severe CAP
1 - benzylpenicillin 10 days
2 - amoxicillin
3 - co-amoxiclav + clarythromycin
antibiotic treatment for:
1 - simple cystitis
2 - hospital acquired UTI
3 - infected urinary catheter
1 - trimethoprim 3 days
2 - cephalexin or Co-amoxiclav
3 - gentamicin
2 invasive conditions due to Group A Streptococcal Infection
2 parts of Tx
severe cellulitis, necrotising fasciitis
Clindamycin + IVIg
Mx of infected urinary catheter
Change catheter + Gentamicin
Mx of C diff
- stop the causative
- If SEVERE, treat with:
- PO metronidazole
- If the above fails, use PO vancomycin
