Infectious disease

Question 1

bacteraemia

Answer 1

bacteria in the blood
does not mean sepsis or clinical significance

Question 2

bacteraemia anaerobic vs aerobic

Answer 2

gram positive rods
gram positive cocci - clusters or chains
gram negative rods
gram negative cocci

Question 3

how are blood cultures processed

Answer 3

machines detect production of CO2 (false positives with high white cell count)
gram stain
rapid identification

Question 4

rapid identification

Answer 4

GeneXpert for staph aureus, MRSA, covid, flu

Question 5

how to maximise blood culture

Answer 5

take before giving antibiotics
if any concern about bacteraemia
fever is largely irrelevant
10ml per bottle
at least 2 sets

Question 6

why shouldnt you put too much blood

Answer 6

because theres only so much reagent in the bottles
eg. charcoal to absorb antibodies and white cells

Question 7

how do we say things are contaminants

Answer 7

coagulase negative staphs eg. strep viridans or enterococcus spp. because they live on the skin and upper respiratory tract
staph aureus can also live on the skin but we never consider it a contaminant because it is so pathogenic

Question 8

golden staph

Answer 8

staph aureus
may be MSSA or MRSA
20-25% mortality at 30 days for golden staph bacteraemia

Question 9

empiric therapy for golden staph bacteraemia

Answer 9

fluclox 2g 4-6 hourly and vacomycin
minimum mandatory 2 weeks IV
always consult ID
always think about bones, joints and heart

Question 10

investigation for staph aureus infections

Answer 10

usually cannula put in when it wasnt necessary
cannulas put in cubital fossa or in emergency situations have higher risk of infection
SAC1 investigation following every hospital acquired staph aureus bacteraemia

Question 11

coagulase negative staph

Answer 11

skin commensals
- staph epidermiidis
- staph hominis
- staph capitis
considered contaminants at time of infection

Question 12

what causes cellulitis

Answer 12

beta haemolytic strep
group A +++
Group B, C, G and F

Question 13

other causes of cellulitis

Answer 13

staphylococcus aureus: abscesses, wound infections, trauma
rare:
- pasteurella multocida and capnocytophaga canimorsus (cats and dogs)
- aeromonus hydrophila and vibrio vulnificus
- pseudomonas aeruginosa
- clostridium perfringens (soil)
- erysipelothrix rhusiopathiae (lobster)

Question 14

Rx for cellulitis

Answer 14

new eTG: ben pen is first line, fluclox only if trauma or wound
high NNT for adding vanc, only if high probability of MRSA

Question 15

what not to do for cellulitis

Answer 15

addition of clindamycin is of no used except maybe toxic shock syndrome

Question 16

UTI common cause

Answer 16

gram negs:
E coli
klebsiella
pseudomonas
enterobacter
serratia
morganella

gram pos:
staph saprophyticus
enterococcus and stretococcus agalactiae are commonly grown but rarely pathogenic
staph aureus - consider blood cultures

candida - often contamination

Question 17

should you treat asymptomatic bacteriuria

Answer 17

no
unless they’re pregnanct because pylonephritis can be dnagerous for the baby if it progresses to this
or treat if theyre going for urological surgery

Question 18

urine culture where there is a bacteraemia as well

Answer 18

do not use this to dteermine Abx choice - because some Abx are good for cystitis but dont work for pylonephritis/bacteraemia eg. trimethoprim

Question 19

ESCAPPM

Answer 19

produce Amp C
use meropenam IV
theyre resistant to tazocin and below

Question 20

UTI in aged care facilities

Answer 20

must have delirium and one other sign before recommending treatment
eg. fever, high CRP, subrapubic treatment
urine culture growth and delirium alone is not sufficient

Question 21

most common cause of bacterial pneumonia

Answer 21

strep pneumoniae

Question 22

aspiration pneumoia

Answer 22

all pneumonia is aspiration
acute chemical injury to the lung parenchyma
anaemorbes above the gut are all penecillin susceptible - can use these unless the patient is aspirating faecal matter