Guidelines to control multidrug-resistant Gram-negative bacteria: an ‘evidence-free zone’

citation needed

I recently had a review published in CMI comparing EU guidelines for controlling multidrug-resistant Gram-negative bacteria (MDR-GNB). I included the following guidelines in my review: ECCMID 2014, Irish MDRO, PHE CPE, HPS CPE, ECDC systematic review on CPE (not strictly a guideline, but did include some recommendations). A couple of important points arise:

  • Evidence-free zone. The major reflection is that the whole area is shrouded in expert opinion, and woefully short on evidence. We don’t have good evidence from intervention studies whether or not even the traditional cornerstones of infection prevention and control (screening, isolation, disinfection etc) are effective against MDR-GNB. We need large, randomised studies to figure out what works to control MDR-GNB.
  • Heterogeneity. MDR-GNB is not like MRSA, VRE or C. difficile, where you have a single organism of concern. It’s a whole family of loosely related bacteria, brought together by a Gram-stain result and resistance to key antibiotics (and in some cases, little else). The ECCMID and Irish MDRO guidelines bravely try to cover all MDR-GNB, whereas the other guidelines focus only on CPE.
  • Hand hygiene, contact precautions and single rooms in. These measures are recommended by all guidelines for all organisms in all settings.
  • HCW screening, and antibiotics for decolonisation out. These measures are recommended against in endemic settings, and only recommended by some guidelines in outbreak settings.
  • Patient screening and environmental disinfection controversial. Patient screening is recommended for some pathogens in some settings by all guidelines, but there is not a great deal of agreement about who to screen, and when. The guidelines make some surprising environmental recommentations. None (not one!) of the guidelines recommend a switch to bleach (in fact, the PHE CPE guidelines recommend against making a product switch for cleaning / disinfection). Also, only the Irish MDRO guidelines recommend hydrogen peroxide vapour (HPV) – and even then only in the event of an ongoing outbreak. I find this very surprising considering the mounting evidence that contaminated surfaces contribute to the transmission of a range of MDR-GNB (especially A. baumannii) and countless studies (albeit most of them low quality) showing that bleach can improve the level of environmental reduction, and HPV can eliminate reservoirs of MDR-GNB.

This was a tricky review to write; I struggled to meaningfully compare the guidelines given their differences in scope and style. But I do hope that the review will serve to highlight the need for urgent research to furnish the evidence-base,and promote useful discussion around some of the more controversial areas for MDR-GNB control.

Image: Ringling College.

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