Infectious disease Flashcards
bacteraemia
bacteria in the blood
does not mean sepsis or clinical significance
bacteraemia anaerobic vs aerobic
gram positive rods
gram positive cocci - clusters or chains
gram negative rods
gram negative cocci
how are blood cultures processed
machines detect production of CO2 (false positives with high white cell count)
gram stain
rapid identification
rapid identification
GeneXpert for staph aureus, MRSA, covid, flu
how to maximise blood culture
take before giving antibiotics
if any concern about bacteraemia
fever is largely irrelevant
10ml per bottle
at least 2 sets
why shouldnt you put too much blood
because theres only so much reagent in the bottles
eg. charcoal to absorb antibodies and white cells
how do we say things are contaminants
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
golden staph
staph aureus
may be MSSA or MRSA
20-25% mortality at 30 days for golden staph bacteraemia
empiric therapy for golden staph bacteraemia
fluclox 2g 4-6 hourly and vacomycin
minimum mandatory 2 weeks IV
always consult ID
always think about bones, joints and heart
investigation for staph aureus infections
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
coagulase negative staph
skin commensals
- staph epidermiidis
- staph hominis
- staph capitis
considered contaminants at time of infection
what causes cellulitis
beta haemolytic strep
group A +++
Group B, C, G and F
other causes of cellulitis
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)
Rx for cellulitis
new eTG: ben pen is first line, fluclox only if trauma or wound
high NNT for adding vanc, only if high probability of MRSA
what not to do for cellulitis
addition of clindamycin is of no used except maybe toxic shock syndrome
UTI common cause
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
should you treat asymptomatic bacteriuria
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
urine culture where there is a bacteraemia as well
do not use this to dteermine Abx choice - because some Abx are good for cystitis but dont work for pylonephritis/bacteraemia eg. trimethoprim
ESCAPPM
produce Amp C
use meropenam IV
theyre resistant to tazocin and below
UTI in aged care facilities
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
most common cause of bacterial pneumonia
strep pneumoniae
aspiration pneumoia
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
