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Updated: Oct 20, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Surveillance for Colonization, Transmission, and Infection With Methicillin-Susceptible Staphylococcus aureus in a
Dennis Nurjadi1, Vanessa M Eichel1, Patrik Tabatabai2
1Department of Infectious Diseases, Medical Microbiology and Hygiene, Heidelberg University Hospital, Heidelberg, Germany.
Importance:
Staphylococcus aureus is one of the leading causes of infections in neonatal intensive care units (NICUs). Most studies in this patient group focus on methicillin-resistant S aureus or the outbreak setting, whereas data for methicillin-susceptible S aureus are limited.
Objectives:
To identify risk factors for S aureus colonization and infections in hospitalized newborns and to investigate S aureus transmission and its dynamics in a nonoutbreak setting.
Design, Setting, And Participants:
This monocentric cohort study in a tertiary NICU in Heidelberg, Germany, enrolled all hospitalized neonates (n = 590) with at least 1 nasal screening swab positive for S aureus. Data were collected from January 1, 2018, to December 31, 2019.
Exposures:
Weekly screening for S aureus colonization was performed for all newborns until discharge.
Main Outcomes And Measures:
The primary end point was any S aureus infection until hospital discharge. Transmission of S aureus and performance of routine typing to detect transmissions were defined as the secondary outcomes of the study.
Results:
In total, 590 newborns were enrolled (276 [46.8%] female and 314 [53.2%] male; 220 [37.3%] with birthweight <1500 g; 477 [80.8%] preterm; 449 [76.1%] singletons; 419 [71.5%] delivered via cesarean section). The median length of stay was 26 (range, 10-62) days. Overall, 135 infants (22.9%) were colonized by S aureus at some time during their hospital stay. The median time to first detection was 17 (interquartile range, 11-37) days. The overall incidence of S aureus infection was 1.7% (10 of 590). Low birth weight (<1500 g [odds ratio, 9.3; 95% CI, 5.9-14.6; P < .001]) and longer hospital stay (odds ratio, 2.3; 95% CI, 1.9-2.7; P < .001) were associated with colonization. Nasal carriage was significantly associated with S aureus infection (odds ratio, 8.2; 95% CI, 2.1-32.3; P = .002). A total of 123 of 135 colonization isolates were sequenced. All recoverable infection isolates (4 of 7) of newborns with colonization were genetically identical to the colonizing isolate. Whole-genome sequencing indicated 23 potential transmission clusters.
Conclusions And Relevance:
The findings of this cohort study suggest that nasal colonization is a relevant risk factor for S aureus infection in a nonoutbreak NICU setting. In colonized newborns, infection and colonization isolates were genetically identical, suggesting that eradication of colonization may be a useful measure to prevent infection. Further investigations are necessary to validate and assess the generalizability of our findings.
Insights
Staphylococcus aureus nasal colonization in newborns is a significant risk factor for infection in neonatal intensive care units (NICUs). Eradicating colonization may help prevent infections in this vulnerable population.
Area of Science:
- Neonatal intensive care
- Infectious diseases
- Microbiology
Background:
- Staphylococcus aureus is a leading cause of infections in neonatal intensive care units (NICUs).
- Limited data exist on methicillin-susceptible S aureus (MSSA) in NICU patients, particularly in non-outbreak settings.
Purpose of the Study:
- To identify risk factors for S aureus colonization and infections in hospitalized neonates.
- To investigate S aureus transmission dynamics in a non-outbreak NICU setting.
Main Methods:
- A monocentric cohort study in a tertiary NICU, enrolling 590 neonates with positive S aureus nasal screening.
- Weekly S aureus colonization screening until hospital discharge.
- Whole-genome sequencing of isolates to identify transmission clusters.
Main Results:
- Overall, 22.9% of neonates were colonized with S aureus.
- Low birth weight (<1500g) and longer hospital stay were associated with colonization.
- Nasal carriage significantly increased the risk of S aureus infection (OR, 8.2).
- Infection and colonization isolates were genetically identical, indicating endogenous transmission.
Conclusions:
- Nasal colonization is a relevant risk factor for S aureus infection in non-outbreak NICU settings.
- Eradication of S aureus colonization may be a strategy to prevent infections in neonates.
- Further research is needed to validate these findings and assess generalizability.
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