Invasive Group B Streptococcus Infections Caused by Hypervirulent Clone of S. agalactiae Sequence Type 283, Hong Kong, China, 20211

Abstract

During September-October 2021, group B Streptococcus bloodstream infections surged among patients hospitalized in Hong Kong. Of 95 cases, 57 were caused by the hypervirulent strain sequence type 283, which at the time was also found in freshwater fish and wet market environments and thus poses a transmission threat.

Keywords: China; GBS; Hong Kong; ST283; Streptococcus agalactiae; bacteremia; group B Streptococcus; meningitis; molecular epidemiology; pyogenic arthritis; sepsis; streptococcal infections; streptococci.

Figure 1

Invasive group B Streptococcus (GBS) infection incidence from September 2–November 6 (weeks 35–44), 2021, in 17 public hospitals across Hong Kong, China. The gray dotted line indicates the weekly mean number of invasive GBS infections for the same weeks in 2019. *Environmental sampling for GBS occurred during week 39 at local wet markets, and during week 40, a special bulletin was issued to raise public awareness of the upsurging cases. ST, sequence type.

Figure 2

Whole-genome single-nucleotide polymorphism tree of group B Streptococcus isolates from patients, freshwater fish, and wet market environment in Hong Kong, China. The tree was rooted at midpoint. Demographics (including the week of isolate collection, hospital cluster, and source of isolate) and molecular characteristics (including STs, presence of antimicrobial resistance genes and virulence genes) of the isolates are indicated in the legend on the left side of the figure. ST283 highlighted in pink under column ST. Visualization of the tree was performed by using iTOL (https://itol.embl.de). ST, sequence type.