Tag Archives: communication

“A Question of Significance”

Confessions of a Microbiologist, , ,

We may not always realise it, but reading and reporting bacterial cultures often involves several decisions, which are often performed sub-consciously. What do we work up on the agar plates? What do we report? How do we report it?  Do we perform and report susceptibilities? Should we add a comment to the report? All these decisions influence how the result is perceived and acted upon by clinicians. Don’t underestimate the influence that the microbiology report can have on how the patient is subsequently managed.

For example, let’s say we receive 5 theatre samples from a patient undergoing a routine prosthetic joint revision, and 1 of the 5 samples has a light growth of Staphylococcus epidermidis. If we report this out with antibiotic susceptibilities, and without a qualifying comment, there is a decent chance that the orthopaedic surgeon will act on this result and the patient may well end up on several weeks of antibiotics. On the other hand, if we suppress the susceptibilities, and add a comment stating. “This result is of doubtful significance. Clinical correlation is required. Antibiotic susceptibilities are available on request.”, then it is very likely that the surgeon will simply note the result and observe the patient.

On the other hand, if we isolated a Cutibacterium acnes from a shoulder aspirate in a patient with a history of rotator cuff repair, then it is likely that this isolate is significant and we should convey the result as such, along with antimicrobial susceptibilities.

Best of all in these cases of course is to liaise directly with the requestor/clinician/surgeon, so that further clinical details can be obtained, the likely significance can be better ascertained, and a subsequent management plan developed. However, this is not always possible, nor practical for every single patient.

Whilst I always encourage pragmatic reporting, one needs to be aware of the potential consequences of reporting something as a likely contaminant. I.e. What if this organism is genuinely causing infection? What are the likely consequences for the patient if it has not been reported as such? Can we obtain further samples for culture to confirm or negate the initial result? With sterile site samples & blood cultures, obviously the stakes are higher than with a simple wound swab, but the same principles apply for both scenarios.

Over-reporting of organisms on agar plates is often driven by inexperience or fear. I have seen it many times in my career. Scientists and clinical microbiologists alike are responsible for ensuring that over-reporting of results is minimised. This is very much a team game. In particular, colonies thought to represent plate contamination should hardly ever make it on to the laboratory report. Along the same lines, when an obvious pathogen, e.g. Staphylococcus aureus is found on a mixed plate, to what extent should the other organisms be worked up and reported. If a plate is clearly growing a mixture of enteric organisms, you need a very good reason not to report it as mixed enteric flora, and leave it at that.

The “easy way out” for the microbiology scientist and the clinical microbiologist is to report everything that is found on the plate along with antimicrobial susceptibilities, and then let the clinician make head or tail of it. However, this is dumbed down microbiology and often leads to sub-optimal management of the patient.

Michael

“Hand holding and Chinese whispers..”

Confessions of a Microbiologist,

As part of my job as a clinical microbiologist, I am usually on the telephone 20-30 times per day.

That is a lot of telephone time for a man…

With regards to outgoing calls, a lot of these are simply information gathering. For example, is this patient with Gram negative bacteraemia on appropriate Gram negative cover? Has this patient with Clostridium difficile infection been isolated and treated? Has this patient with Staphylococcus aureus bacteraemia been investigated properly?

Gathering this information by telephone is of course always a little fraught with difficulty. Trying to get hold of the right person to speak to can take up a lot of valuable coffee drinking time. There is also no guarantee that the information you are given is accurate, and has not evolved along a chain of “Chinese whispers”. Sometimes you finish the phone call no more enlightened than when you started…

Many of these calls would not be necessary if the hospital/health network had a live, real time “Electronic Health Record”, along with an electronic/digital drug chart for each patient. These innovations simply cannot come soon enough to my neck of the woods. Objective, readily accessible clinical information is what microbiologists crave.

Incoming calls are generally from clinicians looking for advice on antibiotics, infection control, optimal samples, etc. Much of the information that I give out could easily be accessed from published clinical guidelines. There is often an element of “hand holding” here, of sharing the responsibility for the decision made, and sharing the blame if something goes wrong..

Personally I was never very good at hand-holding…

And then, once or twice a day, an interesting phone call comes along, one which stimulates the mind, and prompts further thought and reading, and reminds me that I do after all work in a microbiology laboratory, and not a call centre…

Michael