Glycopeptide heteroresistance in coagulase-negative Staphylococci: clinical implications, risk factors, and surveillance
Abstract
Coagulase-negative staphylococci (CoNS) have been identified as the leading cause of
late-onset sepsis in neonatal intensive care units (NICUs), resulting in poorer developmental
outcomes and significant comorbidities. In certain hospital environments, populations of
heteroresistant CoNS develop; this refers to a subpopulation of bacteria that demonstrate
antibiotic resistance, but exist in quantities that are insufficient for detection by conventional
means. Currently, the clinical relevance of these organisms is poorly understood. The aim of this
project is to review and identify risk factors for the acquisition of heteroresistant Staphylococcus
capitis (hVISC) within the NICU at the Health Sciences Centre, and to identify treatment
differences that may affect the outcomes of these infections. To achieve these goals we will: 1)
conduct a chart review of individuals (primarily infants) known to have had a Staphylococcus
capitis infection; 2) we will conduct a case-control review of infants infected with hVISC
compared to non-heteroresistant CoNS and 3) we will conduct surveillance testing on areas
prone to the development of heteroresistant bacteria including NICUs, oncology wards, and
dialysis units through testing of banked blood culture isolates. This project will be done through
the HSC medical records and medical microbiology laboratory, in collaboration with National
Microbiology Laboratory. We expect that this project will identify risk factors associated with
prolonged sepsis due to infection by heteroresistant organisms. Additionally, we expect that the
results of this project may aid in the development of surveillance protocols that address when
and if testing for heteroresistant organisms should be carried out.