Emerging serotype III sequence type 17 group B streptococcus invasive infection in infants: the clinical characteristics and impacts on outcomes.
BACKGROUND
Group B Streptococcus (GBS) is an important pathogen that causes high mortality and morbidity in young infants. However, data on clinical manifestations between different GBS serotypes and correlation with molecular epidemiology are largely incomplete. The aim of this study was to determine the serotype distribution, antimicrobial resistance, clinical features and molecular characteristics of invasive GBS isolates recovered from Taiwanese infants.


METHODS
From 2003 to 2017, 182 non-duplicate GBS isolates that caused invasive disease in infants less than one year of age underwent serotyping, multilocus sequence typing (MLST) and antibiotic susceptibility testing. The clinical features of these infants with GBS disease were also reviewed.


RESULTS
Of the 182 patients with invasive GBS disease, 41 (22.5%) were early-onset disease, 121 (66.5%) were late-onset disease and 20 (11.0%) were late late-onset disease (> 90 days of age). All these patients were treated with effective antibiotics on time. Among them, 51 (28.0%) had meningitis, 29 (16.0%) had neurological complications, 12 (6.6%) died during hospitalization, and 15 (8.8%) out of 170 patients who survived had long-term neurological sequelae at discharge. Serotype III GBS strains accounted for 64.8%, followed by serotype Ia (18.1%) and Ib (8.2%). MLST analysis revealed 11 different sequence types among the 182 isolates and ST-17 was the most dominant sequence type (56.6%). The correlation between serotype III and ST17 was evident, as ST17 accounted for 87.3% of all serotype III isolates. There was an obvious increasing trend of type III/ST-17 GBS that caused invasive disease in infants. All isolates were susceptible to penicillin, cefotaxime, and vancomycin, while 68.1 and 65.9% were resistant to erythromycin and clindamycin, respectively.


CONCLUSIONS
Despite timely and appropriate antibiotic treatment, a significant proportion of invasive GBS disease still inevitably causes adverse outcomes. Further study to explore preventive strategies and development of serotype-based vaccines will be necessary in the future.
['Kao|Yi|Y|', 'Tsai|Ming-Horng|MH|', 'Lai|Mei-Yin|MY|', 'Chu|Shih-Ming|SM|', 'Huang|Hsuan-Rong|HR|', 'Chiang|Ming-Chou|MC|', 'Fu|Ren-Huei|RH|', 'Lu|Jang-Jih|JJ|', 'Hsu|Jen-Fu|JF|']
D000900:Anti-Bacterial Agents D016470:Bacteremia D024881:Drug Resistance, Bacterial D005260:Female D006801:Humans D007223:Infant D007231:Infant, Newborn D008297:Male D008826:Microbial Sensitivity Tests D058885:Multilocus Sequence Typing D065288:Serogroup D012703:Serotyping D013290:Streptococcal Infections D013292:Streptococcus agalactiae
Group B streptococcus Epidemiology Bacteremia Drug resistance Invasive streptococcal infection