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Flashcards in Antibiotics Deck (62):
1

Antibiotic classes

Beta lactams (Penicillin Cephalosporin Monobactams Carbapenems)
Glycopeptides (eg Vancomycin)
Aminoglycosides (eg Gentamicin)
Macrolides (eg Erythromycin )
Tetracyclines (eg Doxycyclin)
Fluoroquinolones (eg Ciprofloxacin)
Others trimethoprim, sulfamethoxasole, metronidazole, clindamycin

2

cell wall agents

Betalatams and glycopeptides

3

ribosomal agents

Macrolides, aminoglycosides, tetracyclines and clindamycin

4

DNA

Fluoroquinolones

5

Bacteriacidal agents

Betalactam drugs
Vancomycin
Fluoroquinolones
Metronidazole
Nitrofruantoin

Aminoglycosides (high dose)
Co-trimoxazole

6

Bacteriostatic agents

Trimethoprim
Sulfamethoxazole
Tetracyclines
Macrolides
Clindamycin
Aminoglycosides (low dose)

7

4 big categories of bacteria

Gram positive
Gram negative
Anaerobes
Atypical

8

Coagulase positive staph =

S. aureus, only one coagulase producing staph in human infection. Coagulase makes them stick in big number

9

Coagulase negative staph =

All other staph, eg staph epidermidis. They are bunched up in 4-8 cocci, unlike the picture.

10

All staph became resistant to penicillin due to

penicilinase production

11

What can be used as synergic agent?

Aminoglycoside for synergic effect

12

What if pt gets a rash with penicillin?

Rash with penicillin -> use first gen cephalosporin like cefazolin. Cephalosporins have some resistance to penicilinase

13

What if anaphylaxis?

If anaphylaxis -> avoid all beta lactam drugs. Use macrolides, clindamycin, vancomycin, fluoroquinolones instead

14

Anti-staph penicillin

Oxacillin, cloxacillin, dicloxacillin and nefcillin
In NZ flucloxacillin
Penicillinase resistant
Don’t work on gram negatives

15

MRSA is basically resistant to all beta lactam drugs

by altering penicillin binding protein. Any antibiotics works in other ways are ok.
Glycopeptide (Vancomycin)
+ Aminoglycosides/clindamycin/fusidic acid for synergic effect

16

When do we use methicillin?

NEVER! It causes allergic (eosinophilic) nephritis -> renal failure
Methicillin is the first penicillin invented with penicilinase resistance

17

Vancomycin

Glycopeptides
Inhibits cell wall synthesis differently
Don’t work as well as penicillin
Steven-Johnson syndrome

18

Penicillin

Cell wall agent
Covers gram positives
Usually the first line agent of choice
They work!

19

syphillis, Strep pyogenes

Penicillin G
Penicillin G dosent have much gram negative activity because it doesn’t get into the cells.
Penicillin G has poor bioavailability whereas amoxi has good oral bioavailablity (one of the reason why its used a lot in primary care setting)

20

extended gram negative cover penicilin

Ampicillin/amoxicillin

21

Good pseudomonas cover penicillin

Piperacillin extended gram negative

22

Penicillinase resistant penicillin

fluclox

23

Cephalosporins
First gen:

G +ve + PEcK (Proteus, E. coli, Klebisiella) eg Cefazolin

24

Cephalosporins
Second gen:

G+ve + HEN (Haemophillus, Enterobacter and Neisseria) + PEcK eg Cefaclor

25

Cephalosporins
Third gen:
Antipseudomonal

more G-ve eg Ceftriaxone
Ceftazidime
Third gen have poor oral bioavailability -> given IV or IM
Third gen crosses BB barrier -> good agent for meningitis

Cefotaxime excreted primarily in urine
Ceftriaxone excreted primarily by liver

26

Cephalosporins
Fourth gen:

Good G +ve and –ve + anti pseudomonal eg Cefepine

27

Carbapenems

Broadest spectrum betalactam drug
G +ve and –ve + anaerobes
Covers pseudomonas
No intracellular coverage e.g. Chlamydia
Betalactamase resistant
Good empiric therapy for invasive disease eg sepsis
Emerging resistance. E. Coli, enterococcus

28

Gram positive bacilli
Claustridia –

difficile, botulinum, tetani (GI tract)
Metronidazole because anaerobes

29

Gram positive bacilli
Listeria monocytogenes (pneumonia)

Resistant to all cephalosporines
Amoxi to treat

30

Gram positive bacilli
Corynebacterium – diptheria

Penicillins, macrolides, fluoroquinolones

31

Enterococcus faecalis
Gram positive bacilli
Multi-drug resistant

Amoxi if sensitive. Vancomycin, linezolid, daptomycin

32

Gram negative cocci
3 medically relevant species
All diplococci
Moraxella is common cause of respiratory tract infection and occasinally UTI

Moraxella catarrhalis
Neisseria gonorrhoeae
Neisseria meningitidis
IV Ceftriaxone if meningitis
Rifampicin for prophylaxis

33

Gram negative cocci
Moraxella catarrhalis

Amoxi is ok but high betalactamase prevalence

34

Gram negative cocci
Neisseria gonorrhoeae

IM Ceftriaxone 250mg single dose

35

Gram negative cocci
Neisseria meningitidis

IV Ceftriaxone if meningitis
Rifampicin for prophylaxis

36

Gram negative bacilli
GI + UTI

E. coli
Salmonella
Shigella
Vibrio
Yersinia
Proteus
Campylobacter
Pseudomonas

37

Gram negative bacilli
Don’t need Abx for diarrhoea unless invasive
Invasive diarrhoea means

blood and fever

38

the most common cause of UTI

E. Coli
BPAC recommends trimethoprim as first line

39

The term Urosepsis is used because of high likelihood of ...
Another organism to keep in mind in urosepsis is

gram –ve organism involvement, especially E coli.
Enterococcus faecalis, G +ve bacilli because E. coli and E. faecalis have high prevalence of resistance + multidrug resistance.

40

Gram negative bacilli
Invasive pathogens

Salmonella
Shigella
Yersinia
Chamylobacter

41

Ascending cholangitis, cholecystitis, peritonitis
usually caused by

Gram negative bacilli
Invasive pathogens
Salmonella
Shigella
Yersinia
Chamylobacter

42

Gram negative bacilli drug of choice

Aminoglycosides
Carbapenems
Fluoroquinolones
3rd and 4th cephalosporines
Monobactams

43

Psudomonas
G –ve bacilli, aerobic
Difficult to treat!! Why?

Multiple mechanisms of Abx resistance
biofilm
Thick wall
Active pump
Extended spectrum betalactamase

CFS, intubated, wound

44

Psudomonas G-ve vacilli, aerobic
antibiotics

Aminoglycosides, tazocin, carbapenem, ceftazedime, fluoroquinolone
Tazocin contains piperacillin and tazobactam – tazobactam must be used due to betalactamase

45

Atypicals
Cannot gram stain

Spirochetes
Syphilis – Penicillin G
Borrelia (lyme’s disease) -Doxy
Mycoplasma - Macrolide
Chlamydia - Macrolide
Mycobacterium – 4 Tb meds
Rikettisia - Doxy

46

4 Tb meds RIPE, and side effects

Rifampin R for red, it stains all ur body fluid red/orange colour.
Isoniazid isoNiazid, N for neuropathy
Pyrazinamide P for Pain in the joint
Ethambutol E for eye, causes retionopathy

47

Anaerobes

C. difficile, botulinum, tetani
Bacteroids - gut
Actinomyces – mouth -> lungs
Disruption of normal flora, poor blood supply and necrosis -> Abscess
Mixed organisms in abscess
Debridement/surgical drainage

48

Anaerobes antibiotics

Metronidazole, clindamycin, a penicillin + betalactamase inhibitor, carbapenem, fluoroquinolone
Clindamycin for above diaphragm. ie dental and lung
Bacteroids, Claustridia, actinomyces

49

Aminoglycosides

Gentamicin and tobramycin
Good gram –ve cover including pseudomonas
Renal and ototoxic
Don’t cross blood brain barrier
Prolonged exposure > 10mcg/ml should be avoided.
Use ideal body weight for calculating the dose
Check the trough level, should be < 2mcg/ml
Dosing interval 8 hours

50

Tetracyclines

Only doxycycline
G +ve and –ve + anaerobe
Good for intracellular organisms
Malaria
Chlamydia
Gonorrhoea
Rickettisia
Low dose therapy for acne
Stains bone and teeth, avoid in pregnancy
Oesophagitis
Photosensitivity

51


Macrolides

Erythro, azithro, roxithro and clarithromycin
Similar spectrum to amoxicillin
Atypical pneumonia – Chlamydia, mycoplasma and legionella
Good for Campylobacter
Long half life
GI upset + disulfiram like action
Potent CYP3A4 inhibitor except azithromycin
Bad if pt is on statin

52

Fluoroquinolones

Old – Ciprofloxacin
New – Levo, gemi and moxifloxacin
Good G +ve and –ve coverage
Good tissue penetration
Cipro – best gram negative potency
Fist line for pyelonephritis
Moxi has good anaerobic cover

GI upset
Elevate BSL especially with gati
Neuropathy – central and peripheral

53

Trimethoprim

First line agent for uncomplicated UTI
Doesn’t cover proteus (Don’t use it if pH is high!!)
Bad in pregnancy
Sulfamethoxazole increases the potency
Covers proteus
Used in uncomplicated paediatric UTI
Prophylaxis for PCP and toxo infection in HIV +ve pt with CD4 cell < 200 cell/microL or 200 x 10^6/L

54

Nitrofurantoin

UTI
Safe in pregnancy unless close to term 36-42 weeks
Possible haemolytic anaemia in neonate

55

Gram positive

Penicillin
Staph – Anti-staph penicillin
MRSA – Vancomycin

56

Gram negative

Aminoglycosides
Fluoroquinolones
Carbapenems
Monobactam
Penicillin and cephalosporines

57

Atypicals

Macrolides or fluoroquinolones for pneumonia
Otherwise depends

58

Anaerobes

Metronidazole
Clindamycin (above diaphragm)

59

For 5th year exam

Nitrofurantoin for UTI during pregnancy if the bug is resistant to amoxicillin
Penicillin G for syphilis
Amoxicillin for Listeriosis
Macrolides for atypical pneumonia
Azithromycin 1g PO stat for chlamydia
Metronidazole for C. difficile, bacterial vaginosis and Giardia
Ceftriaxone for meningitis unless in neonates and pregnancy
Co-trimoxazole for PCP and Toxo prophylaxis
Quadruple therapy for tuberculosis + their side effects
No antibiotics for non bloody diarrhoea
Gentamicin pharmacokinetics

60

Ceftriaxone is not used for meningitis in babies or pregnant women

because of possible listeria infection. Listeria is resistant to all cephalosporins

61

Cotrimoxazole =

bactramrim = trimethoprim + sulfamethoxasol

62

Nitrofurantoin is not recommended in pregnancy 37-42 weeks due to

possible haemolytic anaemia in neonate