The Rise of the New Superbug: What is CPE?

Over the past 20 years, scientists have been observing a worrying increase in the prevalence of a deadly new threat in the fight against hospital-acquired infections (HAIs). Carbapenemase-producing Enterobacteriaceae, otherwise known as CPE, are bacteria which have been steadily building resistance to the most advanced antibiotics, essentially creating an infection which is potentially untreatable.

The risk of this new ‘superbug’ reaching pandemic proportions, and of rapidly increasing cases of mortality, is significant, so it is no surprise that the issue of CPE remains high on the agenda for infection prevention and control professionals. Unfortunately, the nature and associated costs of antibiotic research and development means that a drug-based solution to CPE is unlikely any time soon, meaning that the best approach to preventing a CPE outbreak is to improve hygiene through more effective decontamination in healthcare settings, which can significantly reduce the chances of the infection spreading.

What is CPE?

Enterobacteriaceae are a family of common commensal infectious agents, including salmonella and E. coli, the effects of which can range from moderate to severe, and can even be fatal. The bacteria are resistant due to their production of the enzyme carbapenemase, which disables the drug molecule and renders it ineffective. While CPE’s source is still open to debate, some are attributing it to regions of Asia, and to retirees holidaying in these regions and bringing the bacteria home with them.

How Does CPE Affect Patients?

CPE affects patients in a variety of different ways and certain conditions mean some patients are more at risk from CPE than others. Research has shown that patients with diabetes, and those using mechanical ventilation or parenteral nutrition are also at elevated risk of CPE infections. Infections can manifest in different forms, from urinary tract infections to pneumonia, and are fatal for around 50% of bloodstream infections.

Hospitals and other healthcare settings have been found to be at particular risk of CPE outbreaks, with Perez and Van Duin (2013) stating that up to 75% of cases arise from long-term care facilities or are transferred from other hospitals. A study by Blazejewski et al. (2015) in Critical Care highlighted that many infections in ICU are related to multi-drug resistant organisms (MDRO) and that the environment is a major reservoir for MDRO, with organisms ‘remaining viable on various inanimate surfaces from days to months’. The study also indicated that pathogens are frequently transferred from the environment to patients and the contaminated environment and indirectly through healthcare workers’ hands. These factors, coupled with admission to a room previously occupied by a patient infected with CPE, increase the risk of the new patient picking up the infection from the previous occupant of the room.

Despite hospital cleaning staff following correct manual cleaning protocols, Blazejewski et al. reinforced the statement that ‘current every-day and terminal cleaning methods seem to be microbiologically ineffective’. Weber et al. (2016) referenced several studies which demonstrated that less than 50% of room surfaces were properly cleaned, and, in a study by Huttner and Harbath (2015), only 27 out of 74 MDRO carriers were identified as such on ICU admission, suggesting that an alarming number of patients may have acquired the infection during their stay in hospital, despite manual cleaning procedures being adhered to.

Identifying CPE in the Environment

Outbreaks tend to be identified by patient symptom and colonisation screening. Although studies carry out environmental sampling, this is not standard for detection of the bacteria on a day-to-day basis. Whilst recommended practice is to isolate patients with CPE, the nature of the colonisation and the length of time that the disease remains in the environment – on hard surfaces, etc. – means that this can often be impractical and would end up rendering large numbers of patients in quarantine. In such cases, healthcare professionals must instead adopt stricter cleaning processes to prevent the further spread of infection, including the disinfection of rooms with hydrogen peroxide vapour (HPV) or ultraviolet (UV) light. In order to break the cycle of reinfection, it is also necessary to implement a screening programme to identify patients coming into the healthcare setting with CPE, so that they can be managed accordingly.

Fears for the Future

The Carbapenem class of antibiotics are the most aggressive and potent treatment available, and are administered as a last resort for infections of this kind. Unfortunately, it has been discovered that Enterobacteriaceae produce Carbapenemase, an enzyme that destroys the Carbapenem molecule, rendering the antibiotic ineffective. The resistant nature of the bacteria makes it incredibly difficult to treat, and its resistance to the strongest form of antibiotic means other classes of medication have little to no effect.

Concern regarding the potential impact of CPE on future healthcare provision was notably addressed in mid-2014, when medical directors Dr Paul Cosford and Sir Bruce Keough initiated a public health campaign and took the uncommon action of directly contacting all hospitals with advice and toolkits to help their employees deal with the threat. In their letter introducing the problem, Cosford and Keough identified a finite window of opportunity for minimising the spread of such bacteria through improved hygiene and decontamination. It is projected that if adequate changes are not instigated, Carbapenemase-producing Enterobacteriaceae will become a prominent and widespread issue. Other experts warn that it has the potential to become the new ‘superbug’.

Prevention is Key to Managing CPE

It is clear that in the face of an organism which is resistant to all known forms of drug-based treatments, the only way forward in effectively managing the ongoing challenges of CPE is through improved infection prevention methods. It is also evident from many studies on the subject that manual cleaning practices are limited and vary in terms of their effectiveness, which is why new ‘no-touch’ methods of room disinfection are rising in popularity. Hydrogen peroxide systems are one such ‘no-touch’ method which is being used effectively to combat the threat of CPE.

As described by Weber et al. (2016), hydrogen peroxide is an oxidising agent which produces highly reactive hydroxyl radicals that attack DNA, membrane lipids and other essential cell components. Deprox® is a fully computer-controlled vaporising system using a hydrogen peroxide solution, which has been proven to achieve a log-6 reduction in its efficacy. A room and any shared patient equipment can be effectively decontaminated with Deprox® in just 2.5 hours.

Blazejewski et al. (2015) concluded that routine terminal cleaning followed by hydrogen peroxide treatment is more efficient than routine terminal cleaning alone for disinfection of MDRO-contaminated rooms in the ICU. Weber et al. (2016) also referenced that a growing number of clinical studies have demonstrated that hydrogen peroxide systems such as Deprox®, when used for terminal disinfection, can reduce colonisation or healthcare-associated infections in patients admitted to these hospital rooms.

When hydrogen peroxide systems are deployed as the primary decontamination solution in a healthcare setting, multiple studies have delivered compelling evidence that the level of environmental bioburden is reduced. In the face of rising pressures to balance costs with efficiency, Blazejewski et al. (2015) also raised an important point, that the costs associated with the implementation of a hydrogen peroxide decontamination solution are comparable when considering the lower costs related to the management of HAIs, patient readmissions and so forth. It’s clear that solutions like Deprox® are a heavyweight contender in the battle by healthcare providers to fight back against the ever-increasing risk of CPE.

Efficiency of hydrogen peroxide in improving disinfection of ICU rooms – Blazejewski et al., Critical Care (2015)
Effectiveness of ultraviolet devices and hydrogen peroxide systems for terminal room decontamination: Focus on clinical trials – Weber et al. (2016)
Hydrogen Peroxide room disinfection – ready for the prime time? Huttner and Harbarth, Critical Care (2015)
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