Gram Negatives

Question 1

describe the structure of a Gm -ve cell wall

Answer 1

Inner and outer membrane
thin layer of peptidoglycan between
Lipopolysaccharides facing external environment

Question 2

Which of the classes in the 4C antibiotics is used to treat legionella pneumonia?

Answer 2

Quinolones ( Ciprofloxacin in the 4Cs )

Tx:
Levofloxacin and Co-amoxiclav

Question 3

What monobactam is used in NHS Tayside?

Answer 3

Aztreonam

Question 4

Aztreonam only treats Gm -ves. TRUE/FALSE?

Answer 4

TRUE

does not offer any Gm +ve or anaerobe cover

Question 5

Aztreonam is an alternative to Gentamicin in what group of patients?

Answer 5

Renal impairment

Question 6

Why should Gentamicin not be given to patients with Myasthenia Gravis?

Answer 6

• Impairs neuromuscular transmission

- Causes muscle weakness and therefore resp. depression in these patients

Question 7

What groups of antibiotics may offer Gm -ve cover?

Answer 7

• Beta lactams ( and monobactam )
• Aminoglycosides
• Macrolides
• Tetracyclines
• Chloramphenicol
• Co-trimoxazole
• polymixins

Question 8

Are most Gm -ve infections cocci or bacilli shaped?

Answer 8

Bacilli

only true coccus is Neisseria Veillonella

Question 9

What factors should be considered when pneumonia is suspected?

Answer 9

Hospital or community acquired?
Ventilated not ventilated?
Time of year/ season 
Immunosuppressed?
Pre-existing chronic lung disease 
Epidemiological exposures (e.g. PWID, vaccine status) Travel ( e.g. for resistant gram negs)

Question 10

Describe the Gram stain and shape of haemophilus influenzae

Answer 10

Gm -ve coccobacillus

Question 11

What agar is required for growth of haemophilus influenzae?

Answer 11

Chocolate agar media

Question 12

What antibiotics are active against haemophilus influenzae in the UK?

Answer 12

Amoxicillin

Doxycycline also active

Question 13

What is meant by “atypical” pneumonia?

Answer 13

Any infection causing pneumonia which is NOT strep. pneumoniae

e.g. Mycoplasma /Coxiella burnetii / Legionella pneumophila

Question 14

What treatment is commonly used for “atypical pneumonia”?

Answer 14

• Doxycycline (not very effective against Legionella though)
• Clarithromycin
• Levofloxacin in penicillin allergic severe pneumonia and for Legionella NOTE Cdiff risk

Question 15

Where is Legionella commononly found in the environment?

Answer 15

Lukewarm aerosolised water ( showers, air conditioning, taps, hot tubs )

Question 16

Who is more at risk of legionella infection?

Answer 16

• smokers
• males
• COPD
• Immunosuppressed
• Malignancy
• Diabetes
• dialysis

Question 17

What serogroup of Legionella is responsible for most disease?

Answer 17

Serogroup 1

Question 18

What bacteria are most important with regards to Gm -ve sepsis?

Answer 18

E-coli
Pseudomonas
Neisseria meningitidis
these 3 = most important

Other causes:
Klebsiella
Serratia
Acinetobacter
Enterobacter 
Citrobacter

Question 19

What colour change is observed on MacConkey Agar with sorbitol for Ecoli0157?

Answer 19

changes to bright pink

Question 20

Coliforms covers what types of bacteria?

Answer 20

E-coli
Klebsiella sp
Proteus sp.
Enterobacter sp.
Serratia sp.

Question 21

Give examples of antibiotics which contain another ingredient to breakdown beta-lactamase and attempt to prevent antibiotic resistance

Answer 21

Co amoxiclav (clavulanic acid)

Tazocin (Tazobactam agent)

Question 22

Extended spectrum beta lactamase organisms rule out what antibiotics?

Answer 22

Penicillins, cephalosporins and aztreonam

Question 23

What should be remembered when prescribing for obese and pregnant patients?

Answer 23

They may require extra antibiotic coverage for distribution

Some guidelines are based on a 70kg man (which is not the case in todays society)

Question 24

Why is trimethoprim NOT used in sepsis?

Answer 24

It is bacteriostatic