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The sink as a correctable source of extended-spectrum β-lactamase contamination for patients in the intensive care unit

https://doi.org/10.1016/j.jhin.2014.02.013Get rights and content

Summary

Between December 2010 and April 2012, intensive care unit (ICU) patients in our hospital were infrequently colonized with extended-spectrum β-lactamase-positive bacteria (ESBLs). We hypothesized that these ESBLs originated from patients' room sinks, and this was prospectively investigated by weekly culturing of patients and sinks during a 20-week period. ESBLs were isolated from all 13 sinks. Four patients became colonized with ESBLs that were genetically identical to ESBLs that had previously been isolated from the sink. One of these patients died of pneumonia caused by the ESBL. Transmission from sinks to patients was stopped by integrating self-disinfecting siphons to all sinks on the ICU.

Introduction

During 2011–2012 in the intensive care unit (ICU) of Deventer Hospital, mechanically ventilated patients were screened twice per week according to our protocol for selective gut decontamination. Infrequently, extended-spectrum β-lactamase-positive bacteria (ESBLs) were isolated in these patients' cultures, whose preceding cultures had been negative. These strains were considered to have been acquired on the ICU, but since they belonged to different species with different antibiograms, and since there was no evident relation in time, patient-to-patient transmission was not suspected. The primary source of these ESBLs was not clear; they could have been endogenously selected by antibiotic pressure or acquired exogenously by the hands of medical personnel or medical equipment.1, 2, 3

Gram-negative bacteria have been described as the cause of outbreaks on the ICU; they have been isolated from sinks, and in quantities much higher than found in other niches in patient rooms.4, 5, 6 In previous studies it has been shown that patients can become colonized, and even infected, by bacteria from those sinks.7

The aim of our study was to investigate whether patients in the ICU could have been colonized with ESBLs originating from sinks in the patient rooms, and, if this was the case, whether self-disinfecting siphons could be an effective intervention to prevent future transmissions of ESBLs.

Section snippets

Setting

Deventer Hospital is a 500-bed regional hospital with 21,000 admissions per year. In 2011, there were 3293 ICU patient-days and 1337 ventilation-days. The ICU contains seven single and four double patient rooms each with a sink. The two single rooms have an anteroom with an extra sink, so in total 13 sinks are present. Sinks are used for washing hands and medical instrumentation before disinfection, and flushing water that had been used for washing patients. They are cleaned with water and soap.

Sinks

Every patient room sink contained one or more ESBLs on at least one time-point; 247 out of 260 cultures (95%) were positive (Table I). E. cloacae was the predominant strain. ESBLs were also isolated from sinks of one toilet, scullery room and staff room.

After the intervention, ESBLs have not been found in control cultures of any ICU sink. Non-selective cultures eight months after the intervention showed no growth in 11 out of 18 sinks. Positive cultures contained small amounts of coagulase

Discussion

This study showed that ESBLs were present in every sink in the ICU during a 20-week screening period, and therefore sinks may act as a source of infection. In four ICU patients it was incontrovertibly shown that these bacteria had been transmitted from sink to patient, as sinks had been colonized with identical ESBLs before the patient was admitted to the ICU room. One of these patients died from an infection with an ESBL-positive E. cloacae originating from the sink. These transmissions were

Conflict of interest statement

None declared.

Funding sources

None.

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