1136 infection control & hospital epidemiology october 2015, vol. 36, no. 10


figure 2. Pathogen presence by hospital unit type. (A) The total count of rooms surveilled is indicated, as well as the frequency with which ≥1 target organism (TO) was detected by culture- or PCR-based methods on ≥1 surface housed in a given hospital unit. (B) As above, but positive detection events are expressed as a percentage of rooms surveilled.


pre-intervention baselines at other facilities,19–24 and effective cleaning occurred most of the time (62%–88%, depending on assay). Cleaning, however, did not reliably remove bacterial DNA. Further, E. coli DNA was correlated with inpatient infection rates. To our knowledge, this is the first report of environmental


contamination, cleaning outcomes, and HAI in a newly opened EBD facility using culture-based and molecular assays (includingWGS). As such, it might raise more questions than answers. First, did EBD contribute to the infrequent isolation of environmental MDR? This cannot be determined without studies conducted at more EBD hospitals. Second, should cleaning assessments be reconsidered or redesigned with DNA in mind, and is environmental DNA, particularly from E. coli, more clinically relevant than previously thought? Cleaning appeared to both remove and introduce biomaterial at this facility. Perhaps more aggressive wiping of surfaces, in an attempt to clean better, led to more surface contamination.


Indeed,Manianetal21 found that A. baumannii andMRSA were frequently isolated after as many as 4 rounds of cleaning and disinfection. Based on observations that surfaces cleaned with disinfectants become recontaminated faster than surfaces cleaned with detergents,25 others have suggested that disinfectants might, through cellular or biofilm disruption, release more bacterial DNA or planktonic forms that lead to a rebound effect,which contributes to the acquisition of resistance genes among environmental bacteria.2,3,25 Third, are current methods of genotyping such as PFGE or


spa typing adequate for source attribution or outbreak inves- tigations? Price et al26 recently showed that conventional MRSA genotyping methods can lead to the wrong conclusions regarding relatedness or transmission. Using only PFGE, we might have concluded that environmental MRSA were related to those from infections based on their being >95% similar and from the same ward. However, WGS revealed substantial difference at the genome level.


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