Tag Archives: MDRO

“Vanquishing VRE”

Confessions of a Microbiologist, ,

I am the master of false assumptions…

When a hospital close by was affected by a VanB VRE outbreak, I suspected that my local hospital would be relatively immune, due to its smaller size, different patient cohort and relatively strict antimicrobial stewardship policies.

Of course, my assumptions were wrong! It didn’t take long for the VRE to gain a foothold locally as well. (I am simply carrying my poor form on from the COVID pandemic, where I also made several false assumptions…)

MDRO rates in NZ are relatively low compared to many parts of the world. Even though I work in a reasonably big laboratory covering a population of approximately 500,000, up until recently we could go a whole year between VRE isolates! It has therefore been a bit of a shock to see them appear on an almost daily basis over the past few months, fortunately all from rectal screening samples.

Enterococci are hardy bugs and survive well in the environment, necessitating meticulous cleaning with high-level disinfectant to minimise the risk of onward transmission. Despite our best efforts to date, we have struggled to get on top of the outbreak.

However, the news is not all gloomy. All our isolates so far have been from screening samples, and we have yet to see any clinical infections. Can you really call it an outbreak if you don’t have any clinical infections? Personally, I find it difficult to get excited about something like this unless the patients are clearly unwell.

The laboratory I work in serves secondary level care hospitals and we don’t have many of those highly immunocompromised patients with lots of lines in-situ who tend to run into problems with VRE. Our annual number of Enterococcus faecium bacteraemias is low and it may be that we will not end up with many VRE clinical infections even if it does become endemic.

VanB VREs are still amenable to several different treatment options such as linezolid, teicoplanin, daptomycin, etc. In terms of the MDRO spectrum, VanB VREs are on the milder end, at least on a population level. I would be a lot more worried about a CPE outbreak in the hospital.

It is also a good reminder to us that we cannot afford to relax in the field of antimicrobial stewardship. VREs are in particular selected out by the “3Cs”, namely (3rd generation) Cephalosporins, Ciprofloxacin and Carbapenems. We do well in controlling usage of the first two, maybe not so hot on the carbapenem front.

At the moment we are still trying to “stamp out” VRE from our local hospital. The financial cost and staff time involved in managing a VRE outbreak are not insignificant by any means. At some point, one needs to weigh up the cost-benefit analysis of an eradication approach…

Michael

 

“The Blind Microbiologist”

Confessions of a Microbiologist, The Art of Microbiology, , ,

blindI have authorised a little flurry of urine cultures recently with ESBL producing organisms. A good proportion of these had no clinical details, and a significant proportion were from Rest Home residents.

It is the lack of clinical information which frustrates me the most..

These urine samples could have been taken for any one of the following reasons:

  • a)  The nurse at the Rest Home had decided to routinely dipstick the urine of all the residents.
  • b)  The urine was taken and sent to the lab because there was a “whiff” of urine from the patient.
  • c)  The patient is known to be MDRO colonised, so another urine was taken to ‘check’ if it is still there.
  • d)  The patient gets a 6 monthly urine sample sent to the lab because they are known to have a history of recurrent UTIs.
  • e)  The patient is new to the practice or Rest Home so an initial screening urine was taken off.
  • f)  The patient had symptoms or signs suggestive of an acute urine infection.

It is dangerous to assume that the majority of urines arriving at your lab (without clinical details) are specifically for reason F.

My bet is that this is not the case…

When we release antibiotic susceptibilities from the laboratory on a urine culture, we are essentially giving the green light for antibiotic use. An ‘endorsement’ of sorts, a licence to treat, regardless of the clinical indication. In essence we are reporting susceptibilities “blind”…

However reason F is the only reason listed above where I would actually want to routinely release susceptibilities. It could easily be argued that for the laboratory to release susceptibilities on an MDRO without there being any clinical details, simply represents poor antibiotic stewardship.

My laboratory has recently made the provision of clinical details mandatory for Infectious serology tests. If no clinical details, then the serum is simply stored until they are provided. Uptake by clinicians has been very good, and there have been virtually no complaints. What is there to complain about? The quality gains that we have made from this have been very significant.

I am now wondering whether a similar model should be applied to urine samples. Obviously specimen integrity (and ease of recollection) should be taken into account, but there are a couple of possible models as follows:

  • No clinical details, urine stored for maximum 24 hrs until provided. Otherwise recollect.
  • No clinical details, urine processed, but susceptibilities only released on provision of clinical details.

As microbiologists, I don’t think we should be scared of having these kinds of conversations. In fact, I believe we owe it to our patients…

Michael

p.s. Book sales going well, approximately 50 copies ordered so far. They are being posted within 24 hours of receipt of order but obviously will take a few days to arrive depending on location. Let me know if any problems in the ordering process. Thanks.

“Pressure Control”

Antimicrobial Resistance, , ,

Controlling the volume of Multi-Drug Resistant Organisms (MDROs) within an institution is just as much about controlling the selection pressure as it is about controlling the transmission. (Don’t tell the Infection Control nurses that, but it is absolutely true!)

In my opinion the selection pressure control is actually the more important of the two. There will always be transmission despite our best efforts…

For those who are involved with antimicrobial stewardship and Infection Control, you will be aware that we are very good at monitoring our MRSA/ESBL/VRE/CRE rates etc., etc. We look at pretty graphs illustrating this every month at our committee meetings.

However we are not so good at monitoring our selection pressure. By this I mean that we should be taking 5 or 6 key broad spectrum antibiotics (e.g. meropenem, piperacillin tazobactam, tigecycline, ciprofloxacin, etc.) and monitoring objectively their usage on a month by month or quarter by quarter basis.

Most of us have guidelines on the clinical indications for the appropriate use of these key broad spectrum antibiotics. Some institutions go further and require endorsement by an Infection Specialist before their use. However very few of us actually monitor this usage in an objective fashion and then present these surveillance findings at monthly infection control/stewardship meetings.

I have come across institutions with sophisticated antimicrobial stewardship guidelines and well established anti-microbial stewardship committees. Yet the same institutions can have ITUs where more than half the patients passing through the door will get a carbapenem. An MDRO arriving in such a unit simply thinks all his birthdays have come at once, and will make himself at home in no time at all…

That is selection pressure!

If I was a CEO of a hospital that had a problem with endemic Carbapenem Resistant Enterobacteraciae (CRE), I would want to know exactly how much of each of the key broad spectrum antibiotics were being used in the hospital, and then whereabouts they were being used, by whom, and why.

For me, the antimicrobial pharmacist is one of the key members of any infection control team. You can write as many guidelines as you want, but unless you have a firm handle on exactly how much selection pressure you have in your hospital, and how that pressure is trending over time, you may find yourself sitting on an MDRO time bomb.

Michael

Do bacteria have birthdays? Not sure about that!