Serum N-Glycomics Stratifies Bacteremic Patients Infected with Different Pathogens.

Sayantani Chatterjee,David R Shaw,Morten Thaysen-Andersen,David J Torpy,Rebeca Kawahara,Harry C Tjondro,Marni A Nenke

doi:10.3390/jcm10030516

Abstract

Bacteremia—i.e., the presence of pathogens in the blood stream—is associated with long-term morbidity and is a potential precursor condition to life-threatening sepsis. Timely detection of bacteremia is therefore critical to reduce patient mortality, but existing methods lack precision, speed, and sensitivity to effectively stratify bacteremic patients. Herein, we tested the potential of quantitative serum N-glycomics performed using porous graphitized carbon liquid chromatography tandem mass spectrometry to stratify bacteremic patients infected with Escherichia coli (n = 11), Staphylococcus aureus (n = 11), Pseudomonas aeruginosa (n = 5), and Streptococcus viridans (n = 5) from healthy donors (n = 39). In total, 62 N-glycan isomers spanning 41 glycan compositions primarily comprising complex-type core fucosylated, bisecting N-acetylglucosamine (GlcNAc), and α2,3-/α2,6-sialylated structures were profiled across all samples using label-free quantitation. Excitingly, unsupervised hierarchical clustering and principal component analysis of the serum N-glycome data accurately separated the patient groups. P. aeruginosa-infected patients displayed prominent N-glycome aberrations involving elevated levels of fucosylation and bisecting GlcNAcylation and reduced sialylation relative to other bacteremic patients. Notably, receiver operating characteristic analyses demonstrated that a single N-glycan isomer could effectively stratify each of the four bacteremic patient groups from the healthy donors (area under the curve 0.93–1.00). Thus, the serum N-glycome represents a new hitherto unexplored class of potential diagnostic markers for bloodstream infections.

Highlights

Common bacteria causing gramnegative bacteremia include Escherichia coli associated with urinary tract infections [7,8], and Pseudomonas aeruginosa and Klebsiella pneumoniae commonly associated with lung infections [9,10]
A total of 62 N-glycan isomers spanning 41 different glycan compositions were manually identified from the investigated samples, as shown in Figure 2a
The serum N-glycome showed a hitherto unknown potential to stratify bacteremic patients from healthy donors, and even an ability to segregate individuals infected with different pathogens, as supported by three independent statistical methods

Summary

Introduction

Bacteremia commonly arises from primary bloodstream infections such as intra-vascular catheters, surgery, or untreated urinary tract infections via secondary bloodstream infections that include cuts and wounds on the skin or through bacteria in the nasal airways. Common bacteria causing gramnegative bacteremia include Escherichia coli associated with urinary tract infections [7,8], and Pseudomonas aeruginosa and Klebsiella pneumoniae commonly associated with lung infections [9,10]. Gram-positive bacteremia, on the other hand, is considered a less harmful condition that most often originates from the bacteria residing on the skin and in the gastrointestinal tract [11]. Staphylococcus spp. and Streptococcus spp. are the most common skin microbial flora known for their ability to cause gram-positive bacteremia if they successfully enter the bloodstream in sufficient numbers [12]

Methods

Results

Conclusion