1/9
@rabihmgeha shared a fantastic approach to positive BCx! I use a similar schema, but add ‘Questions to ask the lab/what to do next?’ since #ID usually doesn’t get the ‘critical result’ call from micro, and I want to empower those who do with actionable knowledge.
@rabihmgeha shared a fantastic approach to positive BCx! I use a similar schema, but add ‘Questions to ask the lab/what to do next?’ since #ID usually doesn’t get the ‘critical result’ call from micro, and I want to empower those who do with actionable knowledge.
2/
I arrange the potential Gram stain results that one can be called w/ as follows: Gram(+) cocci, Gram(+) rods, Gram(–) rods, Gram(–) cocci, yeast. Gram(+) cocci are grouped by ‘morphology’ since the lab usually tells you this: clusters, pairs, chains, etc. Fill in with orgs.
I arrange the potential Gram stain results that one can be called w/ as follows: Gram(+) cocci, Gram(+) rods, Gram(–) rods, Gram(–) cocci, yeast. Gram(+) cocci are grouped by ‘morphology’ since the lab usually tells you this: clusters, pairs, chains, etc. Fill in with orgs.
3/
Like @rabihmgeha's schema, the orgs are deliberately ordered this way: Gram(+) orgs are often [skin] contaminants, Gram(–) orgs & yeast are not. Remember that clinician adjudication is the ‘gold standard’ for deciding what is a contaminant!
Like @rabihmgeha's schema, the orgs are deliberately ordered this way: Gram(+) orgs are often [skin] contaminants, Gram(–) orgs & yeast are not. Remember that clinician adjudication is the ‘gold standard’ for deciding what is a contaminant!
4/
Now, w/ the bugs organized, when you get that call from the micro lab, here are 3 questions to ask yourself/the lab:
1) Number of positive bottles/cultures and time to positivity?
2) ‘Shape’ of the bacteria?
3) Aerobic or anaerobic bottle?
Let’s break these questions down.
Now, w/ the bugs organized, when you get that call from the micro lab, here are 3 questions to ask yourself/the lab:
1) Number of positive bottles/cultures and time to positivity?
2) ‘Shape’ of the bacteria?
3) Aerobic or anaerobic bottle?
Let’s break these questions down.
5/
Fewer positive cultures & longer time to positivity suggests a contaminant. Apply Q1) to Gram(+) orgs. Time to positivity tough to interpret unless extreme (ex. 8h v 48h). Can use # of positive cx fact to your advantage – before abx, obtain more cx & increase the denominator!
Fewer positive cultures & longer time to positivity suggests a contaminant. Apply Q1) to Gram(+) orgs. Time to positivity tough to interpret unless extreme (ex. 8h v 48h). Can use # of positive cx fact to your advantage – before abx, obtain more cx & increase the denominator!
6/
Apply Q2) to Gram(+) rods since their shapes are so distinct. There are some uniquely shaped Gram(–) rods too, but rare (think Fusobacterium). Here’s a comparative chart of GPRs to illustrate. A great reason to go to micro lab and review the Gram stain!
Apply Q2) to Gram(+) rods since their shapes are so distinct. There are some uniquely shaped Gram(–) rods too, but rare (think Fusobacterium). Here’s a comparative chart of GPRs to illustrate. A great reason to go to micro lab and review the Gram stain!
7/
Apply Q3) to Gram(+) rods & perhaps Gram(–) rods too. For GPRs, preferential growth in the aerobic v anaerobic bottle helps organize the ‘shape’ chart. Ex: while you await speciation for that aerobic box car shaped GPR, these clues suggest Bacillus, usually a contaminant!
Apply Q3) to Gram(+) rods & perhaps Gram(–) rods too. For GPRs, preferential growth in the aerobic v anaerobic bottle helps organize the ‘shape’ chart. Ex: while you await speciation for that aerobic box car shaped GPR, these clues suggest Bacillus, usually a contaminant!
8/
For Gram(–) rods, the pearl is that Pseudomonas is a ‘strict’ aerobe and ought to grow preferentially in the aerobic bottle – thus, a GNR that grows in the anaerobic bottle first is less likely Pseudomonas. Of course, always exceptions to these pearls, so await speciation!
For Gram(–) rods, the pearl is that Pseudomonas is a ‘strict’ aerobe and ought to grow preferentially in the aerobic bottle – thus, a GNR that grows in the anaerobic bottle first is less likely Pseudomonas. Of course, always exceptions to these pearls, so await speciation!
9/9
Let’s put all this together in a final summary chart.
I have to give credit to @colleenkraftMD for teaching me this approach as a fellow! What do you think #IDTwitter? @CarlosdelRio7 @Ahmed_HBabiker @serotavirus @natesumMRSA @CPSolvers
Let’s put all this together in a final summary chart.
I have to give credit to @colleenkraftMD for teaching me this approach as a fellow! What do you think #IDTwitter? @CarlosdelRio7 @Ahmed_HBabiker @serotavirus @natesumMRSA @CPSolvers
Would love to get your input @JenniferSpicer4 @Armstrws @BonuraErin @MDdreamchaser @BSchwartzinSF @Payal_Patel @IdBowl @MikeWoodworthMD @sargsyanz @josh_nosanchuk @WuidQ @gradydoctor!
