Clinical Characteristics, 90-Day Functional Outcomes, Antimicrobial Susceptibility, and Exploratory Genomic Analysis of Invasive Human Streptococcus suis Infection: A Multicenter Retrospective Study in China.

BACKGROUND

Streptococcus suis is a zoonotic pathogen; survivors of invasive infection may have persistent auditory or vestibular sequelae. To address limited multicenter evidence from China, we characterized 90-day outcomes, antimicrobial susceptibility, and exploratory genomic findings.

METHODS

We retrospectively studied 34 patients with invasive S. suis infection at eight hospitals in four Chinese provinces (2017-2025). Unfavorable outcome was defined as death within 90 days or persistent sequelae at day 90. Minimum inhibitory concentrations were reinterpreted using CLSI viridans-group streptococcal surrogate breakpoints; six recoverable isolates underwent whole-genome sequencing.

RESULTS

Acute cochleovestibular involvement occurred in 11/27 (40.7%) patients with meningitis and 0/7 with nonmeningitic bacteremia/sepsis. Unfavorable outcomes occurred in 17/34 (50.0%) patients, including two deaths; 12/32 (37.5%) survivors had hearing-related sequelae. Acute cochleovestibular involvement was more frequent among patients with unfavorable outcomes (64.7% versus 0%; P < 0.001). All evaluable isolates were susceptible to penicillin (21/21), cefotaxime (19/19), and ceftriaxone (5/5). Resistance was observed in 17/20, 16/20, and 20/20 isolates tested for erythromycin, clindamycin, and tetracycline, respectively. Sequence types were ST1 (n = 3), ST7 (n = 2), and ST25 (n = 1); epf and sly were each detected in five isolates, and mrp in four.

CONCLUSIONS

Substantial hearing-related morbidity supports structured audiological follow-up. Clinical associations and genomic findings remain exploratory and do not establish independent prognostic value or genotype-phenotype causality.