Epidemiology and risk factors for recurrent Staphylococcus aureus colonization following active surveillance and decolonization in the NICU

Abstract

Objectives: To examine neonatal risk factors associated with recurrent Staphylococcus aureus colonization and to determine the genetic relatedness of S. aureus strains cultured from neonates before and after decolonization.Study designSingle-center retrospective cohort study of neonates admitted to the neonatal intensive care unit (NICU) from April 2013 to December 2015, during which weekly nasal cultures from hospitalized NICU patients were routinely obtained for S. aureus surveillance.

Setting: Johns Hopkins Hospital's 45-bed level IV NICU in Baltimore, Maryland.

Methods: Demographics and clinical data were collected on all neonates admitted to the NICU with S. aureus nasal colonization who underwent mupirocin-based decolonization during the study period. A decolonized neonate was defined as a neonate with ≥1 negative culture after intranasal mupirocin treatment. Pulsed-field gel electrophoresis was used for strain typing.

Results: Of 2,060 infants screened for S. aureus, 271 (13%) were colonized, and 203 of these 271 (75%) received intranasal mupirocin. Of those treated, 162 (80%) had follow-up surveillance cultures, and 63 of these 162 infants (39%) developed recurrent colonization after treatment. The S. aureus strains were often genetically similar before and after decolonization. The presence of an endotracheal tube or nasal cannula/mask was associated with an increased risk of recurrent S. aureus colonization (hazard ratio [HR], 2.65; 95% confidence interval [CI], 1.19-5.90; and HR, 2.21; 95% CI, 1.02-4.75, respectively).

Conclusion: Strains identified before and after decolonization were often genetically similar, and the presence of invasive respiratory devices increased the risk of recurrent S. aureus nasal colonization in neonates. To improve decolonization efficacy, alternative strategies may be needed.

Figure 1:

Flow chart used to identify neonates admitted to the Neonatal Intensive Care Unit (NICU) during the study period with Staphylococcus aureus colonization

Figure 2:

Probability of Staphylococcus aureus nasal colonization by birth weight using Kaplan-Meier survival estimates and time from admission to the Neonatal Intensive Care Unit (NICU). NOTE: NICU – Neonatal Intensive Care Unit; Btwt – Birth weight; S. aureus – Staphylococcus aureus Administrative censoring occurred at 14 weeks and 122 neonates did not have birth weights documented