Antimicrobial Agents 2 Flashcards

1
Q

What are broad spectrum antibiotics good for?

A

An optimal initial choice for nosocomial pneumonia and severe sepsis.

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2
Q

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

A

Gram stain:
CSF
Joint aspirate
Pus

Rapid antigen detection
Immunofluorescence
PCR

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3
Q

When is each route of antibiotic administration appropriate?

A

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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4
Q

When is it recommended to switch from IV to PO?

A

Recommended in hospital for most infections if the patient has stabilised after 48 hours IV therapy

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5
Q

What are the three patterns of activity for antibiotics?

A

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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6
Q

What are the Type I antibiotics?

A

Aminoglycosides

Daptomycin

Fluoroquinolones

Ketolides

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7
Q

What is the goal of Type I antibiotics?

A

Maximize concentrations

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8
Q

What are the Type II antibiotics?

A

Carbapenems

Cephalosporins

Erythromycin

Linezolid

Penicillins

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9
Q

What is the goal of Type II antibiotics?

A

Maximize duration of exposure

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10
Q

What are the Type III antibiotics?

A

Azithromycin

Clindamycin

Oxazolidinones

Tetracyclines

Vancomycin

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11
Q

What is the goal of Type III antibiotics?

A

Maximize amount of drug

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12
Q

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

A

7 days

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13
Q

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

A

6 weeks

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14
Q

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

A

4-6 weeks

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15
Q

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

A

10 days

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16
Q

What is the recommended length for a course of antibiotics for Simple cystitis (in women)?

A

3 days

17
Q

What are common skin infections and what pathogens cause them?

A

Impetigo, Cellulitis and Wound Infections

Common organisms include S. aureus and beta-haemolytic Streptococci

18
Q

What antibiotics are used to treat skin infections?

A

Flucloxacillin (unless penicillin allergy or MRSA)

19
Q

What is the treatment for Invasive Group A Streptococcal (iGAS)?

A

Aggressive and early debridement

Antibiotics – adjunctive use of protein synthesis inhibitors esp. clindamycin (also has good skin & soft tissue penetration)

Use of IVIg

20
Q

What is the Eagle effect?

A

Penicillin doesn’t have a good effect at a higher concentration, also pencillin isn’t good against high concentrations of bacteria.

21
Q

Why does the Eagle effect happen?

A

In cases of high bacterial burden, the bacteria isn’t actually replicating so penicillin doesn’t really work.

22
Q

What is the treatment for pharyngitis?

A

Benzyl penicillin x 10 days

23
Q

What is the treatment for mild community acquired pneumonia?

A

Amoxicillin

24
Q

What is the treatment for severe community acquired pneumonia?

A

Co-amoxiclav and clarithromycin

25
Q

What are hospital-acquired respiratory tract infections?

A

Second most common cause of HAI

Associated with highest mortality (23%)

Greatest risk associated with tracheal intubation and mechanical ventilation

26
Q

What is the treatment for hospital-acquired respiratory tract infections?

A

Cephalosporin; ciprofloxacin; piperacillin/tazobactam

If MRSA colonised/risk, consider addition of Vancomycin

27
Q

What are the main bacteria for meningitis?

A

N. Meningitidis
S. pneumoniae

Listeria in the very young/elderly/immuno-compromised

28
Q

What is the treatment for meningitis?

A

Ceftriaxone (+/- amoxycillin if Listeria likely)

29
Q

What is the treatment for meningitis in a baby less than 3 months old?

A

Cefotaxime PLUS Amoxicillin (to cover for listeriosis)

Ceftriaxone not used in neonates as displaces bilirubin from albumin and because it can cause biliary sludging

30
Q

What is the treatment of Neisseria meningitidis?

A

Benzylpenicillin (high dose) or Ceftriaxone/Cefotaxime

31
Q

What is the treatment for community acquired simple cystitis?

A

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

32
Q

What is the treatment for hospital-acquired UTI (commonest type of HAI)?

A

Cephalexin or co-amox

33
Q

What is the treatment for an infected urinary catheter?

A

Change under gentamicin cover

34
Q

What is the treatment for C. diff?

A

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.

35
Q

What are things to recover if there is no improvement within 48 hours?

A

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)?