Nosocomial spread of carbapenem resistant enterobacteraceae (CRE) is an emerging threat worldwide. A contaminated hospital environment often serves as a source for the spread of resistant genes via health care workers. In this study, we investigate the source of a prolonged but sporadic nosocomial outbreak of a unique blaGES-5 containing CRE and the epidemiological link between cases identified at a large tertiary care hospital from October 2010 through August 2015.
Patients were identified as being colonized or infected with a blaGES-5 containing CRE through clinical cultures. After the outbreak was identified, further cases were identified through screening or surveillance cultures. Multiple environmental samples were collected from patients’ rooms in attempt to identify a source.
Seven patients were infected or colonized with bacteria harboring the blaGES-5 gene over a 5 year period. A blaGES-5 Escherichia coli was isolated from 2 patients in cardiovascular intensive care (CVICU), Serratia marcescens was isolated from 3 patients in general systems intensive care (GSICU), and Raoutella planticola was isolated from 2 patients in CVICU. All patients acquired infection or colonization > 2 weeks after hospitalization. Environmental swabs were taken from all rooms where positive patients were identified. Positive results were identified from sink drains in 2 rooms in CVICU. After increased cleaning, the sink drains from one of the CVICU rooms was persistently culture negative while the drain from the other room remained positive. The sinks were replaced and the new sinks were tested for the presence of blaGES-5 on a monthly basis and were negative for a period of 6 months but then became positive again. This coincided with a shortage of the accelerated hydrogen peroxide gel that was used on a weekly basis. When this product was reintroduced, the sink again became negative.
The most likely source of the outbreak was a contaminated sink given the persistence of the growth despite measures being taken to eradicate the bacteria. This highlights the difficulty in eradicating biofilm in hospital water systems. In the absence of eradication, diligence with respect to hand hygiene and ongoing surveillance is of paramount importance.
R. Wiens, None
S. Smith, None
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