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Updated: May 3, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Methicillin-resistant Staphylococcus aureus colonization: a three-year prospective study in a neonatal intensive care
Daniela M Geraci1, Mario Giuffrè2, Celestino Bonura2
1Department of Sciences for Health Promotion and Mother-Child Care "G. D'Alessandro", University of Palermo, Palermo, Italy ; PhD School in Food and Human Nutrition, University of Palermo, Palermo, Italy.
Background:
Methicillin resistant Staphylococcus aureus (MRSA) is a major etiological agent of infection in neonatal intensive care units (NICUs). Routes of entry of this organism can be different and the transmission pathway complex. Colonized neonates are the main endogenous reservoir.
Methods And Results:
We conducted a prospective three-year study on MRSA colonization recruiting 722 neonates admitted between 2009 and 2012. Nasal swabs were cultured weekly and MRSA isolates were submitted to molecular typing. The annual incidence density of acquisition of MRSA ranged from a maximum of 20.2 cases for 1000 patient-days during the first year to a minimum of 8.8 cases in the second one to raise again up to 13.1 cases during the third year. The mean weekly colonization pressure fluctuated from 19.1% in the first year to 13.4% in the second year and 16.8% in the third year. It significantly correlated with the number of MRSA acquisitions in the following week. Overall, 187 (25.9%) subjects tested positive for MRSA. A non multiresistant, tst positive, ST22-MRSA-IVa spa t223 strain proved to be endemic in the NICU, being identified in 166 (88.8%) out of 187 colonized neonates. Sporadic or epidemic occurrence of other strains was detected.
Conclusions:
An MRSA strain belonging to the tst1 positive, UK-EMRSA-15/ "Middle Eastern Variant" appeared to be endemic in the NICU under investigation. During the three-year period, substantial changes occurred in case-mix of patients moving towards a higher susceptibility to MRSA colonization. The infection control procedures were able to decrease the colonization rate from more than 40% to approximately 10%, except for an outbreak due to a CA-MRSA strain, ST1-MRSA-IVa, and a transient increase in the colonization prevalence rate coincident with a period of substantial overcrowding of the ward. Active surveillance and molecular typing contributed to obtain a reliable picture of the MRSA dissemination in NICU.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) colonization in neonatal intensive care units (NICUs) was studied over three years. Effective infection control measures reduced colonization rates, despite challenges like patient case-mix changes and overcrowding.
Area of Science:
- Neonatal infectious diseases
- Microbiology
- Public health
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of infection in neonatal intensive care units (NICUs).
- Neonates can be colonized, serving as a reservoir for MRSA transmission.
- Understanding MRSA transmission pathways in NICUs is crucial for infection control.
Purpose of the Study:
- To prospectively investigate MRSA colonization dynamics in a NICU over three years.
- To identify endemic MRSA strains and monitor acquisition rates.
- To evaluate the impact of infection control strategies on MRSA colonization.
Main Methods:
- Prospective three-year study (2009-2012) involving 722 neonates.
- Weekly nasal swabs for MRSA culture and molecular typing.
- Analysis of colonization pressure, incidence density, and strain prevalence.
Main Results:
- MRSA acquisition incidence density varied annually, from 8.8 to 20.2 cases per 1000 patient-days.
- Mean weekly colonization pressure correlated with subsequent MRSA acquisitions.
- A specific ST22-MRSA-IVa strain was endemic, found in 88.8% of colonized neonates.
Conclusions:
- A tst1-positive MRSA strain (UK-EMRSA-15/
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