ICHE special edition on CRE and MDROs

CRE medium

Infection Control and Hospital Epidemiology have once again excelled themselves in putting together a fine special edition on CRE and MDROs. Around this time last year I posted an article on the ICHE special edition on the role of the environment, and this special edition is equally important. I strongly recommend that you read the special edition from cover to cover, but I’ve picked out a few of my personal highlights below:

  • A thoughtful editorial by Drs Lautenbach and Perencevich sets the scene. They reflect on our ‘woeful unpreparedness’ to address both current and future MDROs.
  • A number of articles provide updates on surveillance and prevalence. Brennan et al. report findings from a 6-month CRE point-prevalence survey based on voluntary reporting in the state of Michigan, finding a crude rate of 1.07 cases per 10,000 patient days. Interestingly, this rate was almost 3 cases per 10,000 patient days in long-term acute care facilities. Isolates were not collected and analyzed, so carbapenemase genes were not confirmed; the fact that close to 10% of isolates were susceptible to meropenem suggests that a good number of the CRE were not carbapenemase producers. Indeed, another state-level point-prevalence survey (Pfeiffer et al., from Oregon) found that only 3 of the 60 CRE isolates reported were carbapenemase producers. Another state-level survey of CRE (Johnson et al., from Michigan) identified regional clustering of CRE colonization of mechanically ventilated patients in the central region of the state.
  • Analysis through the SHEA Research Network found that contact isolation policies for multidrug-resistant Gram-negative rods (MDR-GNR) are surprisingly variable. Worryingly, almost 20% of facilities surveyed did not isolate patients infected or colonized with MDR Pseudomonas or Acinetobacter, and 6% do not isolate patients with CRE. Policies for de-escalation of contact precautions were equally variable. Contact isolation policies seem to be even more lax in long-term care facilities based on data from Pfeiffer et al., reporting that only half of patients colonized with MDROs are placed on contact precautions.
  • A number of studies evaluated risk factors for CRE. For example, Bhargava et al. identified high acute morbidity score, immunosuppression, presence of indwelling medical devices and prior antimicrobial exposures to be consistent risk factors for CRE in the various patient populations they evaluated.
  • A survey of the kitchen in a Swiss hospital identified ESBL-producing Enterobacteriaceae in 92% of raw chicken and 6% of rectal samples from food handlers.
  • The efficacy of chlorhexidine bathing for MDR-GNR has been questioned, so data from Lin et al. on this issue are particularly welcomed. In a study of 62 patients in a long-term acute care facility, daily chlorhexidine gluconate (CHG) bathing halved the chances of culturing CRE from the body sites analyzed. However, it’s worth noting that the measured CHG skin concentration (15-312 mg/L before the daily bath and 78-1250 mg/L after the daily bath) was much lower than the applied CHG concentration (10,000 mg/L). This potentially brings the subtly reduced susceptibility to CHG reported in MRSA into play.
  • Several studies evaluated the potential for environmental contamination with MDR-GNR. Rosa et al. found that exposure to surfaces contaminated with MDR A. baumannii increased the risk of acquisition by almost 3-fold. Although the design of the study was fundamentally different, it is interesting to note that the increased risk from admission to a room previously occupied by a patient with MDR A. baumannii was also around 3-fold in a previous study. Havill et al. reported that the survival time for CRE (including K. pneumoniae) on dry surfaces is measured in weeks not days. Rock et al. carefully observed 220 unique interactions between healthcare workers (HCW) and patients with KPC or non-KPC producing K. pneumoniae, finding that HCW gloves or gowns became contaminated during 14% of the 220 interactions, and 26% of 43 environmental samples were positive. There was no significant difference between HCW or environmental contamination rates for KPC vs. non-KPC producing K. pneumoniae.
  • There was not much on therapy for CRE – perhaps because there is little to say for pan-drug resistant CRE! An article discussing the challenges of managing CRE infections by Drekonja et al. through surveying the CDC funded Emerging Infections Network highlighted the common problems due to toxicity from using “last-line” antimicrobials colistin and tigecycline.

It seems that the prevalence of CRE is patchy in the USA at present, and that long-term care, and long-term acute facilities are an integral part of the story. Given the limited evidence base, interventions need to cover all bases: active surveillance, rapid and accurate diagnostics, environmental (and perhaps food) hygiene, contact isolation and perhaps antiseptic decolonization, all combined with facility-wide education and communication initiatives. The most effective – and cost-effective – interventions to prevent and control the spread of CRE and other MDR-GNR are controversial so to this end I am looking forward to the SHEA ‘From MRSA to CRE: Controversies in MDROs’ and joint HIS / IPS ‘What’s that coming over the hill: rising to the challenge of resistant Gram-negative rods’ Spring meetings next month!

Photo credit: Enterobacter cloacae NDM-1 growing on Oxoid Brilliance CRE Agar by Nathan Reading.


7 thoughts on “ICHE special edition on CRE and MDROs

  1. very nice Jon – Damien Mack will present our initial screening for CPE and other carbapenem resistant organisms at Birmingham Infection Control day in April; and we will have results shortly on our hospital wide prevalence survey on risk factors for MDRO in our hospital population.
    very important to identify
    1. best screening strategies in endemic and non endemic populations
    2. best lab methodologies
    3. options for decolonisation
    4. how to manage isolation


    • Thanks for the comment Susan, and sounds like some very exciting data – I look forward to seeing it next month. What do you think about a molecular vs. agar-based method for screening? Clearly each has it’s advantages, but I’m leaning towards a molecular approach.


  2. Thanks for sharing Jon! CRE is certainly the talk of the town these days particularly with facilities who have not seen it previously and are uncertain as to how to control it once it arrives


  3. Hi Nathan. It’s a great image, both for the training and untrained eye. What are you standard methods for detecting CRE in Birmingham? We’re just about to take a look at a molecular method as a potential front line, but are currently using frankly rather insensitive conventional micro methods!


    • We use again very insensitive methods – Biomerieux ChromID Carba and ESBL for direct plating of rectal screening swab and nutrient broth with Imipenem 10ug antibiotic disk – then subcultured at 18-24h to ChromID Carba and ESBL. Weve picked some NDM and KPC this way. Thankfully we haven’t had any Oxa48 (we think!) as these are often more tricky to screen for as they can be relatively sensitive. We use Rosco Diagnostics confirmation discs for phenotypic confirmation of Carbapenemase producers and other information from antibiogram such as pan -resistance to aminoglycosides to gain info on type of Carbapenemase eg NDM vs VIM for MBL’s. This works well but is not perfect, we also wish to look at molecular for screening and confirmation so may look at BD MAX with CheckPoints or GeneXpert Carba R once its launched. We want something simple to democratise the testing so we don’t need specialists to do the work and to offer 7/7 testing


      • Nathan, fascinating view from the trenches, so to speak. Thanks. By insensitive, I mean really insensitive – MacConkey with an ertapenem disc, which may pick up a KPC on a good day. I think your direct + enrichment chromogeneic media approach seems pretty sensitive (although not for OXA as you rightly say). It will be interesting to see how the emerging molecular assays perform.


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