Outbreak investigation of Serratia marcescens neurosurgical site infections associated with a contaminated shaving razors

Surgical site infection (SSI) is the most common healthcare-associated infection. We report an outbreak of neurosurgical site infections caused by Serratia marcescens after craniotomy in a tertiary care hospital. Between August 6 and 21, 2018, five cases of early-onset SSI caused by S. marcescens after craniotomy were recorded in a 1786-bed tertiary care hospital. Cultures were collected from potential environmental sources and healthcare workers. Whole-genome sequencing (WGS) was used to investigate the genetic relationships among S. marcescens isolates. The outbreak involved five patients; S. marcescens was isolated from the cerebrospinal fluid, pus, tissue, and blood samples from these patients. S. marcescens was also isolated from shaving razors and brushes. All S. marcescens isolates from the infected patients and razors showed the same resistance patterns on antibiotic-susceptibility tests. WGS revealed close clustering among four of five isolates from the patients and among three of four isolates from the razors. No additional patient developed S. marcescens infection after we stopped using the razors for scalp shaving. We report an outbreak of neurosurgical site infections after craniotomy, which was associated with shaving razors contaminated by S. marcescens. Shaving scalps with razors should be avoided to prevent SSI.