Antimicrobial Agents 2 Flashcards
What are broad spectrum antibiotics good for?
An optimal initial choice for nosocomial pneumonia and severe sepsis.
What are some things which can be used to help identify the pathogen?
Gram stain:
CSF
Joint aspirate
Pus
Rapid antigen detection
Immunofluorescence
PCR
When is each route of antibiotic administration appropriate?
IV - Serious (or deep-seated) infection.
PO - Usually easy, but avoid if poor GI function or vomiting. Different classes of antimicrobial have different oral bioavailabilities.
IM - Not an option for long-term use. Avoid if bleeding tendency or drug is locally irritant.
Topical - Limited application and may cause local sensitisation.
When is it recommended to switch from IV to PO?
Recommended in hospital for most infections if the patient has stabilised after 48 hours IV therapy
What are the three patterns of activity for antibiotics?
Type I - Concentration-dependent killing and prolonged persistent effects
Type II - Time-dependent killing and minimal persistent effects
Type III - Time-dependent killing and moderate to prolonged persistent effects.
What are the Type I antibiotics?
Aminoglycosides
Daptomycin
Fluoroquinolones
Ketolides
What is the goal of Type I antibiotics?
Maximize concentrations
What are the Type II antibiotics?
Carbapenems
Cephalosporins
Erythromycin
Linezolid
Penicillins
What is the goal of Type II antibiotics?
Maximize duration of exposure
What are the Type III antibiotics?
Azithromycin
Clindamycin
Oxazolidinones
Tetracyclines
Vancomycin
What is the goal of Type III antibiotics?
Maximize amount of drug
What is the recommended length for a course of antibiotics for N. meningitidis meningitis?
7 days
What is the recommended length for a course of antibiotics for Acute osteomyelitis (adult)?
6 weeks
What is the recommended length for a course of antibiotics for bacterial endocarditis?
4-6 weeks
What is the recommended length for a course of antibiotics for Gp A Streptococcal pharyngitis?
10 days
What is the recommended length for a course of antibiotics for Simple cystitis (in women)?
3 days
What are common skin infections and what pathogens cause them?
Impetigo, Cellulitis and Wound Infections
Common organisms include S. aureus and beta-haemolytic Streptococci
What antibiotics are used to treat skin infections?
Flucloxacillin (unless penicillin allergy or MRSA)
What is the treatment for Invasive Group A Streptococcal (iGAS)?
Aggressive and early debridement
Antibiotics – adjunctive use of protein synthesis inhibitors esp. clindamycin (also has good skin & soft tissue penetration)
Use of IVIg
What is the Eagle effect?
Penicillin doesn’t have a good effect at a higher concentration, also pencillin isn’t good against high concentrations of bacteria.
Why does the Eagle effect happen?
In cases of high bacterial burden, the bacteria isn’t actually replicating so penicillin doesn’t really work.
What is the treatment for pharyngitis?
Benzyl penicillin x 10 days
What is the treatment for mild community acquired pneumonia?
Amoxicillin
What is the treatment for severe community acquired pneumonia?
Co-amoxiclav and clarithromycin
What are hospital-acquired respiratory tract infections?
Second most common cause of HAI
Associated with highest mortality (23%)
Greatest risk associated with tracheal intubation and mechanical ventilation
What is the treatment for hospital-acquired respiratory tract infections?
Cephalosporin; ciprofloxacin; piperacillin/tazobactam
If MRSA colonised/risk, consider addition of Vancomycin
What are the main bacteria for meningitis?
N. Meningitidis
S. pneumoniae
Listeria in the very young/elderly/immuno-compromised
What is the treatment for meningitis?
Ceftriaxone (+/- amoxycillin if Listeria likely)
What is the treatment for meningitis in a baby less than 3 months old?
Cefotaxime PLUS Amoxicillin (to cover for listeriosis)
Ceftriaxone not used in neonates as displaces bilirubin from albumin and because it can cause biliary sludging
What is the treatment of Neisseria meningitidis?
Benzylpenicillin (high dose) or Ceftriaxone/Cefotaxime
What is the treatment for community acquired simple cystitis?
Trimethoprim x 3 days (7 for men and pregnant women)
Nitrofurantoin x 3 days (7 for men and pregnant women)
Nitro preferred in first 2 trimesters
What is the treatment for hospital-acquired UTI (commonest type of HAI)?
Cephalexin or co-amox
What is the treatment for an infected urinary catheter?
Change under gentamicin cover
What is the treatment for C. diff?
STOP the offending antibiotic (usually a cephalosporin);
If severe, Rx with PO vancomycin.
If above fails, use PO fidaxomicin.
Final step IV metronidazole + oral vanc.
What are things to recover if there is no improvement within 48 hours?
Does the patient really have a bacterial infection? (Have I collected the relevant cultures?)
Is there a persistent focus present (e.g. an infected vascular or urinary catheter)?
Is there a deep-seated collection (e.g. intra-abdominal) that requires drainage?
Could the patient have bacterial endocarditis?
Am I using the correct dose of the antimicrobial?
Is another infection present (esp consider Candida)?
