Microbiology 21: Antimicrobial Agents 2

Question 1

What are the 2 common organisms that cause skin infections such as Impetigo or Cellulitis ?

What antibiotic is commonly used to treat these ?

Answer 1

Staph Aureus
Beta haemolytic streptococcus (Strept. pyogenes)

Flucloxacilin

Question 2

Which 2 toxicities must you consider when giving aminoglycosides ?

Answer 2

Ototoxicity
Nephrotoxicity

Question 3

Which antibiotic is common used to treat mild typical CAP ?

Answer 3

Amoxicillin

Usually due to pneumococcus and Haemophilus

Question 4

What is the most common causative organism of CAP ?

Answer 4

Streptococcus pneumonia

Question 5

List 3 atypical organisms that cause CAP ?

Answer 5

Legionella, Mycoplasma, Chlamydia

Usually associated with severe CAP

Question 6

Which antibiotic is commonly used to treat Bacterial meningitis ?

What can you add to the Tx and why?

Answer 6

Ceftriaxone

Can add Amoxicillin if Listeria is likely (groups at risk of this are < 3-month-old babies, > 65 year olds, pregnant women)

Question 7

Why is ceftriaxone not given to children under 3 months of age ?

Answer 7

Causes biliary sludging (displaces bilirubin from albumin)

Therefore give cefotaxime AND amoxicillin (the latter for listeria cover)

Question 8

List 2 sequele you worry about after a streptococcal infection ?

Answer 8

Glomerulonepohritis
Rheumatic fever

Hence why it needs to be treated for 10 days

Question 9

Which antibiotics are commonly used to treat HAP ? (4)

Answer 9

• Cephalosporin
• Ciprofloxacin
• Tazocin
• If MRSA, consider addition of vancomycin

Question 10

Which antibiotic is commonly used to treat simple cystitis in the community setting ?

Answer 10

Trimethoprim (3 days)

Question 11

Which antibiotic is commonly used to treat Hospital acquired UTI ? (NB most common type of HAI)

Answer 11

Cephalexin or Co-amoxiclav

Question 12

Which antibiotic is common used to treat atypical CAP ?

Answer 12

Macrolide (Erythromycin/Clarythromycin) + Tetracycline (doxycycline)

Question 13

Which antibiotic is common used to treat severe typical CAP ?

Answer 13

Penicillin (Co-amoxiclav) + Macrolide (Clarithromycin)

Question 14

Which antibiotics are used to treat HAP due to aspiration ?

Answer 14

Cefuroxime + metronidazole

Question 15

Which antibiotics are used to treat atypical CAP with confirmed legionella ?

Answer 15

Rifampicin + Macrolide (Erythromycin, Clarythromycin)

Question 16

Which antibiotics could be used to treat HAP with Pseudomonass spp. ?

Answer 16

Tazocin (pippericilin + Tazobactam) or ciprofloxacin + gentamicin

Question 17

What is the treatment for primary Syphilis ?

Answer 17

IM benzyl penicillin

Question 18

What is the treatment for N.Ghonorrhoea ?

Answer 18

IM ceftriaxone

Question 19

What is the treatment for Chlamydia ?

Answer 19

Doxycycline (or azithromycin)

Question 20

What is the treatment for BV ?

Answer 20

Metronidazole

Question 21

What is the treatment for Trichomoniasis ?

Answer 21

Metronidazole

Question 22

What is the treatment of bacterial meningitis due to N.meningitidis or S.Pneumonia ?

Answer 22

Ceftriaxone + Prednisolone

Question 23

What is the treatment of bacterial meningitis due to Listeria ?

Answer 23

Ceftriaxone + Ampicillin + Prednisolone

Question 24

name two methods of antibiotic susceptibility testing

Answer 24

MIC (minimum inhibitory concentration) - this is the least amount of drug required to inhibit the growth of the organism in a culture

Agar disc diffusion method

Question 25

when is IV to PO switching of antibiotics usually recommended What is an exception to this?

Answer 25

if the patient has stabilised after 48 hrs of IV treatment In CNS infections and severe infections such as osteomyelitis and endocarditis, you may NOT switch to PO

Question 26

describe the 3 main patterns of antibiotic activity

Answer 26

TYPE 1: concentration dependent killing and prolonged persistent effects eg aminoglycosides TYPE 2: time dependent killing and minimal persistent effects eg carbapenems, penicillins TYPE 3: time dependent killing and moderate to prolonged persistent effects

Question 27

what are the lengths of treatment for the following: - N meningitidis meningitis - Acute osteomyelitis - bacterial endocarditis - group A strep pharyngitis - simple cystitis

Answer 27

1 - 7 days 2 - 6 weeks 3 - 4-6 weeks 4 - 10 days 5 - 3 days

Question 28

antibiotic or choices for: 1 - pharyngitis 2 - mild CAP 3 - severe CAP

Answer 28

1 - benzylpenicillin 10 days 2 - amoxicillin 3 - co-amoxiclav + clarythromycin

Question 29

antibiotic treatment for: 1 - simple cystitis 2 - hospital acquired UTI 3 - infected urinary catheter

Answer 29

1 - trimethoprim 3 days 2 - cephalexin or Co-amoxiclav 3 - gentamicin

Question 30

2 invasive conditions due to Group A Streptococcal Infection 2 parts of Tx

Answer 30

severe cellulitis, necrotising fasciitis Clindamycin + IVIg

Question 31

Mx of infected urinary catheter

Answer 31

Change catheter + Gentamicin

Question 32

Mx of C diff

Answer 32

* stop the causative * If _SEVERE_, treat with: * **PO metronidazole** * If the above fails, use **PO vancomycin**