Advertisement

Screening for carbapenem-resistant organisms

      The alarming rise of carbapenem-resistant organisms, and specifically the carbapenemase-producing Enterobacteriaceae, in the last five years in many countries is raising the prospect of endemic, untreatable, pan-resistant infections.
      • Wilson A.P.R.
      • Livermore D.M.
      • Otter J.A.
      • et al.
      Prevention and control of multi-drug-resistant Gram-negative bacteria: recommendations from a Joint Working Party.
      Infection control is the principal line of defence, and screening and isolation are used to prevent transmission. Unlike meticillin-resistant Staphylococcus aureus, there is no effective means of suppressing excretion of these organisms from a carrier in the healthcare environment. Screening also requires a rectal rather than a nasal swab. Containment requires effective contact precautions and single room accommodation. However, the number of patients with potential risk factors far exceeds the number of actual carriers, so isolation facilities could rapidly be overwhelmed while awaiting results of screening cultures. In determining which patients to screen and isolate, each hospital has to reach a pragmatic solution that balances the need to identify carriers against the anticipated numbers and available isolation facilities.
      Working Party recommendations to control spread were published in this Journal in January 2016.
      • Wilson A.P.R.
      • Livermore D.M.
      • Otter J.A.
      • et al.
      Prevention and control of multi-drug-resistant Gram-negative bacteria: recommendations from a Joint Working Party.
      The main recommendations were to test meropenem susceptibility in all significant Gram-negative isolates and to screen patients at risk (i.e. admissions to intensive care or from long-term care facilities or stay in hospital with endemic cases in the last year). However, the report was not prescriptive concerning other risk factors that might indicate the need for patient screening. There was no recommendation for repeated screening of patients before concluding that they did not pose a risk, and long-term carriage was assumed once screening was reported as positive. Earlier guidelines had advised pre-emptive isolation and screening of patients who had previously been carriers, or had stayed in an overseas hospital or any hospital with endemic carbapenemase-producing Enterobacteriaceae in the last year.
      • Public Health England
      Acute trust toolkit for the early detection, management and control of carbapenemase-producing Enterobacteriaceae.
      Patients required three negative screens to be considered clear. Other publications recommended screening and contact precautions for all extended-spectrum β-lactamase producers.
      • Tacconelli E.
      • Cataldo M.A.
      • Dancer S.J.
      • et al.
      ESCMID guidelines for the management of the infection control measures to reduce transmission of multidrug-resistant Gram-negative bacteria in hospitalized patients.
      In practice these recommendations are difficult to implement in most hospitals because isolation facilities are insufficient for the large number of patients identified as at risk.
      Limiting screening to patients in specific specialties thought to be at risk could detect up to half the total patients with carbapenem-resistant Enterobacteriaceae entering the hospital and be more practicable than screening individual patients based on their risk factors. Vella et al. found that individual risk factors detected fewer than half of carriers, but, even assuming 100% sensitivity and specificity for screening, the potential demand on isolation beds was unfeasibly high if pre-emptive isolation were attempted.
      • Vella V.
      • Moore L.S.P.
      • Robotham J.V.
      • et al.
      Isolation demand from carbapenemase-producing Enterobacteriaceae screening strategies based on a West London hospital network.
      Selecting and screening high-risk specialties reduced the chance of errors and saved costs. However, the proportion of cases detected was greatly affected by the specialties selected and the nature of the patient population within that specialty. Hence individual hospitals still have to decide a local strategy based on the epidemiology in their own patient population. Already many hospitals have decided to routinely screen all admissions to intensive care units.
      As has been observed in southern Europe within the last few years, occasional outbreaks of infection may progress rapidly to endemic presence. In areas where carbapenem-resistant Enterobacteriaceae are already highly prevalent, control may be difficult to achieve because of the number of unidentified carriers, many without recognized risk factors. Intermittent screening of the whole inpatient population might be a useful method of containing further spread and achieving control. Carbapenemase-producing Enterobacteriaceae, mostly Klebsiella pneumoniae, was found at a prevalence of 11% in a point screening in one Manchester hospital. Only 8% had been previously identified.
      • Poole K.
      • George R.
      • Decaene V.
      • et al.
      Active case finding for carbapenemase-producing Enterobacteriaceae in a teaching hospital: prevalence and risk factors for colonization..
      Within the 70 carriers identified, logistic regression showed age and antibiotic use to be significant factors in the risk of colonization. Isolation of such a large proportion of the patient population would be challenging and might require designating multiple isolation wards. Such a strategy is both difficult to staff adequately and expensive in terms of efficiency of bed use. In practice, isolation would have to be prioritized according to the risk of infection to that patient population and the individual’s risk of spreading infection.
      The consequences of a failure to control spread, especially of the pan-resistant strains, are far reaching. However, mandatory reporting and co-ordinated national infection control approaches encompassing acute and long-term care facilities are still effective, even in that situation, but require considerable leadership from central government.
      • Schwaber M.J.
      • Lev B.
      • Israeli A.
      • et al.
      Israel Carbapenem-Resistant Enterobacteriaceae Working Group
      Containment of a country-wide outbreak of carbapenem-resistant Klebsiella pneumoniae in Israeli hospitals via a nationally implemented intervention.

      References

        • Wilson A.P.R.
        • Livermore D.M.
        • Otter J.A.
        • et al.
        Prevention and control of multi-drug-resistant Gram-negative bacteria: recommendations from a Joint Working Party.
        J Hosp Infect. 2016; 92: S1-S44
        • Public Health England
        Acute trust toolkit for the early detection, management and control of carbapenemase-producing Enterobacteriaceae.
        PHE, London2013 (Available at:) ([last accessed July 2016])
        • Tacconelli E.
        • Cataldo M.A.
        • Dancer S.J.
        • et al.
        ESCMID guidelines for the management of the infection control measures to reduce transmission of multidrug-resistant Gram-negative bacteria in hospitalized patients.
        Clin Microbiol Infect. 2014; 20: 1-55
        • Vella V.
        • Moore L.S.P.
        • Robotham J.V.
        • et al.
        Isolation demand from carbapenemase-producing Enterobacteriaceae screening strategies based on a West London hospital network.
        J Hosp Infect. 2016; 94: 118-124
        • Poole K.
        • George R.
        • Decaene V.
        • et al.
        Active case finding for carbapenemase-producing Enterobacteriaceae in a teaching hospital: prevalence and risk factors for colonization..
        J Hosp Infect. 2016; 94: 125-129
        • Schwaber M.J.
        • Lev B.
        • Israeli A.
        • et al.
        • Israel Carbapenem-Resistant Enterobacteriaceae Working Group
        Containment of a country-wide outbreak of carbapenem-resistant Klebsiella pneumoniae in Israeli hospitals via a nationally implemented intervention.
        Clin Infect Dis. 2011; 52: 848-855