The Gram-negative bacterial family of Enterobacteriaceae, includes the species Klebsiella, Enterobacter, and Escherichia. These bacteria can cause opportunistic wound infections, gastroenteritis, pneumonia and septicaemia, particularly in hospital patients, including post-operative patients. Carbapenem-resistant Enterobacteriaceae (CRE) is now a serious concern for the NHS (1).
In 2009, reports first emerged from the USA that these new hospital-acquired, antibiotic-resistant bacteria, had caused death in hospital patients. A prediction was made at this time that CRE could be even harder to eradicate than methicillin-resistant Staphylococcus aureus (MRSA) or antibiotic-resistant Clostridium difficile.
Following reports of cases of CRE in more than a dozen hospitals in England and Scotland in 2009, the then Health Protection Agency (HPA) (now Public Health England) issued a warning about what it called, ‘a notable public health risk’(1). Initially, CRE was thought to be imported from patients having had surgery in India and CRE was considered to be a consequence of the increasing number of UK patients travelling abroad for surgery each year (> 100,000 in 2013) (2).
In 2015, a joint collaboration between Imperial College Healthcare NHS Trust, Imperial College Academic Health Sciences Centre (AHSC) and Imperial College London has created a new multidisciplinary research group, the Antimicrobial Research Collaborative (ARC) (3,4). The aim of the ARC is to translate research findings into new infection prevention strategies. This initiative will have an important role in addressing the problem of antimicrobial resistance (AMR).
As part of the ARC collaboration, in April 2015 researchers lead by Professor Alison Holmes, Director of the National Institute for Health Research (NIHR) Health Protection Research Unit (HPRU), Imperial College London, published their review of current CRE screening strategies in the Journal of Infection(5,6). Among the findings of this study, they noted that admissions to high-risk specialties were likely to have higher CRE prevalence rates and that the higher prevalence of CRE resulted in higher detection rates and lower false-positivity rates (6). These researchers have recommended that CRE screening should be prioritised for hospital admissions to high-risk specialties (6).
The CRE strains are resistant to all the standard antibiotics now used in the NHS. Furthermore, some of these resistant bacteria have been shown to survive in hospital environments, such as table surfaces and door handles.
In May 2015, a publication by Weber and colleagues in the US, in the journal Infection Control & Hospital Epidemiology (ICHE) (published online in Feb 2015), reported that CRE-infected patients contaminated the environmental surfaces of hospital rooms in 8.4% of cases, but at low levels (7). Three species of CRE, Enterobacter, Klebsiella, and Escherichia, survived poorly, with 15% survival after 24 hours and 0% survival after 72 hours (7).
The survival of enteric organisms, such as CRE, is likely to be less than the survival of MRSA on hospital surfaces, due to differences in the structure of the bacterial cell capsule. The ICHE study shows that the levels of contamination and survival are high enough to be important in terms of CRE transmission (7).
In conclusion, carbapenem-resistant Enterobacteriaceae (CRE) are an important group of infections for the new multidisciplinary antimicrobial resistance (AMR) teams to target. Despite their reported limited growth and survival on hospital surfaces, the increasing number of reported cases supports the view that now is not the time to be complacent about hospital infection control.
If you would like to comment on any of the issues raised by this article, particularly from your own experience or insight, Healthcare-Arena would welcome your views.
(1) Public Health England. https://www.gov.uk/government/organisations/public-health-england Accessed June 16, 2015
(2) Office for National Statistics, Travel Tends 2013. http://www.ons.gov.uk/ons/dcp171776_361237.pdf Accessed June 16, 2015
(3) Imperial College Healthcare NHS Trust. http://www.imperial.nhs.uk Accessed June 16, 2015
(4) The Antimicrobial Research Collaborative (ARC), Imperial College, London. http://www.imperial.ac.uk/arc Accessed June 16, 2015
(5) The National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Healthcare Associated Infections and Antimicrobial Resistance, Imperial College London. http://www1.imperial.ac.uk/hpruantimicrobialresistance/ Accessed June 16, 2015
(6) Venanzio V, Gharbi M, Moore LS, Robotham J, Davies F, Brannigan E, Galletly T, Holmes AH. Screening suspected cases for carbapenemase-producing Enterobacteriaceae, inclusion criteria and demand. J Inf 2015;pii:S0163-4453(15)00197-8. http://www.ncbi.nlm.nih.gov/pubmed/26070742 Accessed June 16, 2015
(7) Weber DJ, Rutala WA, Kanamori H, Gergen MF, Sickbert-Bennett EE. Carbapenem-resistant Enterobacteriaceae: frequency of hospital room contamination and survival on various inoculated surfaces. Infect Control Hosp Epidemiol. 2015;36(5):590-3. http://www.ncbi.nlm.nih.gov/pubmed/25661968 Accessed June 16, 2015