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.