Bacterial Whole Genome Sequencing on the Illumina iSeq 100 for Clinical and Public Health Laboratories

Abstract

Bacterial whole-genome sequencing (WGS) provides clinical and public health laboratories an unprecedented level of information on species identification, antimicrobial resistance, and epidemiologic typing. However, multiple barriers to widespread adoption still exist. This research describes bacterial WGS using the Illumina iSeq 100 instrument to overcome some of these barriers. Using an in-house, high-quality single-nucleotide polymorphism analysis pipeline and a commercial whole-genome multilocus sequence typing program, the sequencing of Acinetobacter baumannii, Burkholderia cepacia, Clostridioides difficile, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, and Staphylococcus aureus isolates was validated. The genome coverage range was 17× to 149×, with a mean of 59×. The limit of detection for single-nucleotide polymorphisms was 30×. Overall platform base calling accuracy was >99.999%. Reproducibility and repeatability of base calling inferred from whole-genome multilocus sequence typing was species dependent and ranged from >97% similarity for P. aeruginosa to >99.9% similarity for S. aureus. Resistance gene and multilocus sequence typing allele identification was 100% concordant with expected results. A simple, modified library preparation reduces the per-sample cost by half to give overall theoretical sample costs ranging from approximately $50 to $100 for library preparation and sequencing. The iSeq 100 provides a cost-effective and easy-to-use platform for clinical and public health laboratories to sequence bacterial isolates for a wide range of potential applications.