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Comparative Study
. 2021 Sep 23;16(9):e0257821.
doi: 10.1371/journal.pone.0257821. eCollection 2021.

The NICU flora: An effective technique to sample surfaces

Naomi Sultan  1 , Irina Shchors  2 , Marc V Assous  3   4 , Maskit Bar-Meir  4   5
Affiliations
Comparative Study

The NICU flora: An effective technique to sample surfaces

Naomi Sultan et al. PLoS One. .

Abstract

Objective: Environmental surface sampling in healthcare settings is not routinely recommended. There are several methods for environmental surface sampling, however the yield of these methods is not well defined. The aim of the present study is to compare two methods of environmental surface sampling, to characterize the neonatal intensive care unit (NICU) flora, compare it with rates of infection and colonization and correlate it with the workload.

Design and setting: First, the yield of the swab and the gauze-pad methods were compared. Then, longitudinal surveillance of environmental surface sampling was performed over 6 months,once weekly, from pre-specified locations in the NICU. Samples were streaked onto selective media and bacterial colonies were identified using matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF).

Results: The number of colonies isolated using the gauze pad method was significantly higher compared with the swab method. Overall, 87 bacterial species of 30 different bacterial genera were identified on the NICU environmental surfaces. Of these, 18% species were potential pathogens, and the other represent skin and environmental flora. In 20% of clinical cultures and in 60% of colonization cultures, the pathogen was isolated from the infant's environment as well. The number of bacteria in environmental cultures was negatively correlated with nurse/patient ratio in the day prior to the culture.

Conclusion: The gauze pad method for environmental sampling is robust and readily available. The NICU flora is very diverse and is closely related with the infants' flora, therefore it may serve as a reservoir for potential pathogens.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Frequently touched surfaces in the neonatal intensive care unit from which surface cultures were obtained: Computer mouse, the monitor screen knob, drawer handles, incubator handles and the surface of the counters.
Fig 2
Fig 2. Number of colonies isolated in environmental cultures obtained by swab moistened with 0.9% Nacl (dotted bars) vs. gauze pad moistened with Mueller-Hinton broth (vertical stripes).
Fig 3
Fig 3. Bacterial genera isolated from surface cultures in the neonatal intensive care unit.
Fig 4
Fig 4. The number of colonies grown from environmental surface cultures by site of culture and environmental vs. pathogenic bacteria.
See this image and copyright information in PMC

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