High-throughput capsular serotyping of Staphylococcus aureus.

GRUNERT T; WENNING M; SORDELLI DO; BUZZOLA FR; EHLING-SCHULTZ M

CHICAGO, ILLINOIS, USA

Simposio; International Symposium on Staphylococcus and Staphylococcal Infections (ISSSI); 2014

International Symposium on Staphylococcus and Staphylococcal Infections (ISSSI)

Staphylococcus aureus frequently causes chronicinfections in humans (e.g. cystic fibrosis, osteomyelitis) and animals (e.g.bovine mastitis). Since, the prevalence of non-encapsulated strains was foundto be higher in chronic than in acute infections, down-regulation of capsularpolysaccharide (CP) production could be a survival strategy duringstaphylococcal host adaptive processes. Thus, loss of CP expression mightrepresent an important indicator for persistence and a continuous monitoring ofCP expression could provide information about the progression of bacterialadaptation to its host niche. We therefore developed a high-throughput methodfor discrimination of the clinically important S. aureus capsular serotypes 5, 8 and non-typeable (NT)based on metabolic fingerprinting by Fourier-transform infrared (FTIR)spectroscopy and chemometrics. A comprehensive set of human and animal derivedclinical isolates, representative for each CP type, were used to develop anartificial neural network assisted FTIR typing system. Our study coulddemonstrate that FTIR spectroscopy allows a fast and reliable discrimination ofcapsule expressing and nonexpressing strains from human as well as from bovineorigin. Furthermore, we were able to follow the transition from encapsulated tonon-encapsulated subpopulations during a three months, weekly monitoring of achronically infected dairy cow. These naturally selected strains represent anideal starting point for an in depth analysis of factors contributing to the persistenceof S. aureus in the bovine mammarygland.