Antimicrobial Agents 2 Flashcards by Kat Qiao

What are broad spectrum antibiotics good for?

An optimal initial choice for nosocomial pneumonia and severe sepsis.

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What are some things which can be used to help identify the pathogen?

Gram stain:
CSF
Joint aspirate
Pus

Rapid antigen detection
Immunofluorescence
PCR

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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.

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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

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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.

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What are the Type I antibiotics?

Aminoglycosides

Daptomycin

Fluoroquinolones

Ketolides

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What is the goal of Type I antibiotics?

Maximize concentrations

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What are the Type II antibiotics?

Carbapenems

Cephalosporins

Erythromycin

Linezolid

Penicillins

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What is the goal of Type II antibiotics?

Maximize duration of exposure

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What are the Type III antibiotics?

Azithromycin

Clindamycin

Oxazolidinones

Tetracyclines

Vancomycin

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What is the goal of Type III antibiotics?

Maximize amount of drug

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What is the recommended length for a course of antibiotics for N. meningitidis meningitis?

7 days

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What is the recommended length for a course of antibiotics for Acute osteomyelitis (adult)?

6 weeks

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What is the recommended length for a course of antibiotics for bacterial endocarditis?

4-6 weeks

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What is the recommended length for a course of antibiotics for Gp A Streptococcal pharyngitis?

10 days

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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)?