Antibiotics

Question 1

Antibiotic classes

Answer 1

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

Question 2

cell wall agents

Answer 2

Betalatams and glycopeptides

Question 3

ribosomal agents

Answer 3

Macrolides, aminoglycosides, tetracyclines and clindamycin

Question 4

DNA

Answer 4

Fluoroquinolones

Question 5

Bacteriacidal agents

Answer 5

Betalactam drugs
Vancomycin 
Fluoroquinolones
Metronidazole
Nitrofruantoin 

Aminoglycosides (high dose)
Co-trimoxazole

Question 6

Bacteriostatic agents

Answer 6

Trimethoprim
Sulfamethoxazole
Tetracyclines
Macrolides
Clindamycin
Aminoglycosides (low dose)

Question 7

4 big categories of bacteria

Answer 7

Gram positive
Gram negative
Anaerobes
Atypical

Question 8

Coagulase positive staph =

Answer 8

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

Question 9

Coagulase negative staph =

Answer 9

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

Question 10

All staph became resistant to penicillin due to

Answer 10

penicilinase production

Question 11

What can be used as synergic agent?

Answer 11

Aminoglycoside for synergic effect

Question 12

What if pt gets a rash with penicillin?

Answer 12

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

Question 13

What if anaphylaxis?

Answer 13

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

Question 14

Anti-staph penicillin

Answer 14

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

Question 15

MRSA is basically resistant to all beta lactam drugs

Answer 15

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

Question 16

When do we use methicillin?

Answer 16

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

Question 17

Vancomycin

Answer 17

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

Question 18

Penicillin

Answer 18

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

Question 19

syphillis, Strep pyogenes

Answer 19

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)

Question 20

extended gram negative cover penicilin

Answer 20

Ampicillin/amoxicillin

Question 21

Good pseudomonas cover penicillin

Answer 21

Piperacillin extended gram negative

Question 22

Penicillinase resistant penicillin

Answer 22

fluclox

Question 23

Cephalosporins

First gen:

Answer 23

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

Question 24

Cephalosporins

Second gen:

Answer 24

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

Question 25

Cephalosporins Third gen: Antipseudomonal

Answer 25

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

Question 26

Cephalosporins | Fourth gen:

Answer 26

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

Question 27

Carbapenems

Answer 27

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

Question 28

Gram positive bacilli | Claustridia –

Answer 28

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

Question 29

``` Gram positive bacilli Listeria monocytogenes (pneumonia) ```

Answer 29

Resistant to all cephalosporines | Amoxi to treat

Question 30

Gram positive bacilli | Corynebacterium – diptheria

Answer 30

Penicillins, macrolides, fluoroquinolones

Question 31

Enterococcus faecalis Gram positive bacilli Multi-drug resistant

Answer 31

Amoxi if sensitive. Vancomycin, linezolid, daptomycin

Question 32

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

Answer 32

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

Question 33

Gram negative cocci | Moraxella catarrhalis

Answer 33

Amoxi is ok but high betalactamase prevalence

Question 34

Gram negative cocci | Neisseria gonorrhoeae

Answer 34

IM Ceftriaxone 250mg single dose

Question 35

Gram negative cocci | Neisseria meningitidis

Answer 35

IV Ceftriaxone if meningitis | Rifampicin for prophylaxis

Question 36

Gram negative bacilli | GI + UTI

Answer 36

``` E. coli Salmonella Shigella Vibrio Yersinia Proteus Campylobacter Pseudomonas ```

Question 37

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

Answer 37

blood and fever

Question 38

the most common cause of UTI

Answer 38

E. Coli | BPAC recommends trimethoprim as first line

Question 39

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

Answer 39

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.

Question 40

Gram negative bacilli | Invasive pathogens

Answer 40

Salmonella Shigella Yersinia Chamylobacter

Question 41

Ascending cholangitis, cholecystitis, peritonitis | usually caused by

Answer 41

``` Gram negative bacilli Invasive pathogens Salmonella Shigella Yersinia Chamylobacter ```

Question 42

Gram negative bacilli drug of choice

Answer 42

``` Aminoglycosides Carbapenems Fluoroquinolones 3rd and 4th cephalosporines Monobactams ```

Question 43

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

Answer 43

``` Multiple mechanisms of Abx resistance biofilm Thick wall Active pump Extended spectrum betalactamase ``` CFS, intubated, wound

Question 44

Psudomonas G-ve vacilli, aerobic | antibiotics

Answer 44

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

Question 45

Atypicals | Cannot gram stain

Answer 45

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

Question 46

4 Tb meds RIPE, and side effects

Answer 46

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

Question 47

Anaerobes

Answer 47

``` 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 ```

Question 48

Anaerobes antibiotics

Answer 48

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

Question 49

Aminoglycosides

Answer 49

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

Question 50

Tetracyclines

Answer 50

``` 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 ```

Question 51

Macrolides

Answer 51

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

Question 52

Fluoroquinolones

Answer 52

``` 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

Question 53

Trimethoprim

Answer 53

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

Question 54

Nitrofurantoin

Answer 54

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

Question 55

Gram positive

Answer 55

Penicillin Staph – Anti-staph penicillin MRSA – Vancomycin

Question 56

Gram negative

Answer 56

``` Aminoglycosides Fluoroquinolones Carbapenems Monobactam Penicillin and cephalosporines ```

Question 57

Atypicals

Answer 57

Macrolides or fluoroquinolones for pneumonia | Otherwise depends

Question 58

Anaerobes

Answer 58

Metronidazole | Clindamycin (above diaphragm)

Question 59

For 5th year exam

Answer 59

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

Question 60

Ceftriaxone is not used for meningitis in babies or pregnant women

Answer 60

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

Question 61

Cotrimoxazole =

Answer 61

bactramrim = trimethoprim + sulfamethoxasol

Question 62

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

Answer 62

possible haemolytic anaemia in neonate