Methicillin-SusceptibleStaphylococcus aureusin Skin and Soft Tissue Infections, Northern Italy

Marco Tinelli,Antonio Ceraminiello,Annalisa Pantosti,Maurizio Vimercati,Monica Monaco

doi:10.3201/eid1502.080010

Abstract

During February 2004-September 2006, familial clusters and sporadic cases of Staphylococcus aureus skin and soft tissue infections were observed in a suburban area near Milan in northern Italy. Molecular typing of the isolates showed an epidemic methicillin-susceptible S. aureus (MSSA) strain, spa type 005 and sequence type 22 that harbored Panton-Valentine leukocidin (PVL) genes. The first case-patients were neonates or mothers who had recently delivered in the local hospital. Examination of the medical records showed a cluster of postpartum mastitis and neonatal skin infections antedating the emergence of infections in the community. Nasal swabs of neonates, mothers, and hospital staff were positive for the epidemic MSSA. Hospital circulation of the strain was interrupted by implementation of infection control measures, although infections continued to occur in the community. The PVL-positive MSSA strain resembles typical community-acquired methicillin-resistant S. aureus in its ability to cause prolonged community and hospital outbreaks of skin infections.

Highlights

During February 2004–September 2006, familial clusters and sporadic cases of Staphylococcus aureus skin and soft tissue infections were observed in a suburban area near Milan in northern Italy
We have described a large and prolonged outbreak caused by a Panton-Valentine leukocidin (PVL)-positive methicillin-susceptible S. aureus (MSSA) strain that was probably initiated in the maternity ward and nursery of the local hospital and spread to the community
Striking similarities exist between the principal features of this outbreak and recent descriptions of outbreaks caused by typical CA-methicillinresistant Staphylococcus aureus (MRSA)

Summary

Introduction

During February 2004–September 2006, familial clusters and sporadic cases of Staphylococcus aureus skin and soft tissue infections were observed in a suburban area near Milan in northern Italy. This report describes a large and prolonged community and hospital outbreak of skin and soft tissue infections caused by a PVL-positive MSSA strain. During March–June 2006, eleven additional cases of S. aureus skin and soft tissue infections occurred in patients who lived in the same area in different households and who were not related to the family clusters.

Results

Conclusion