Clinical characteristics and antibiotic susceptibility features of different types of invasive infections caused by group B Streptococcus: a multicenter prospective study

Abstract

Objective To study the clinical manifestations and antibiotic sensitivity features of early- and late-onset invasive infections caused by group B Streptococcus (GBS). Methods A total of 96 infants with invasive GBS infections were enrolled prospectively from seven tertiary hospitals of GBS Infection Research Cooperative Group in southwest Fujian, such as Xiamen Maternal and Child Care Hospital, etc., from January 2016 to June 2018. According to the onset time of infection after birth, they were divided into early-onset GBS disease (GBS-EOD) group (<7 d, n=67) and the late-onset GBS disease (GBS-LOD) group (7-89 d, n=29). Clinical manifestations, disease spectrum, complications and outcomes of the two groups were compared. Drug sensitivity test was carried out using disk diffusion test. Chi-square or Fisher's exact test, two independent sample t-test or Mann-Whitney U tests were used for statistical analysis. Results (1) The average ages at onset in GBS-EOD and GBS-LOD groups were (15.8±6.7) h (0.5-142.0 h) and (25.0±8.1) d (9-89 d), respectively. The incidence of tachypnea, pallor, fever and convulsion were noted in 68.7% (46/67) vs 44.8% (13/29), 52.2% (35/67) vs 17.2% (5/29), 23.9% (16/67) vs 65.5% (19/29) and 7.5% (5/67) vs 48.3% (14/29) of GBS-EOD and GBS-LOD groups with χ2 values of 6.282, 10.199, 15.146 and 21.237 (all P<0.05). The main clinical manifestations of GBS-EOD were tachypnea and pallor, while most of the patients in the GBS-LOD group developed fever and convulsions. (2) The incidence of pneumonia, sepsis, meningitis, sepsis complicated by septic joints, pneumonia complicated by sepsis, sepsis complicated by meningitis and pneumonia complicated by sepsis and meningitis were noted in 43.3% (29/67) vs 20.7% (6/29), 9.0% (6/67) vs 17.2% (5/29), 0.0% (0/67) vs 3.4% (1/29), 0.0% (0/67) vs 6.9% (2/29), 31.3% (21/67) vs 13.8% (4/29), 6.0% (4/67) vs 31.0% (9/29) and 10.4% (7/67) vs 6.9% (2/29) of GBS-EOD and GBS-LOD groups. There was a statistically significant difference in the disease spectrum between the two groups (Fisher's exact test, all P<0.001). Compared with the GBS-LOD group, the GBS-EOD group had a higher incidence of pneumonia [85.1% (57/67) vs 41.4% (12/29), χ2=19.116, P<0.001] and a lower incidence of meningitis [16.4% (11/67) vs 41.4% (12/29), χ2=6.922, P=0.009]. Complications such as acute respiratory distress syndrome (ARDS), pulmonary hemorrhage, shock and persistent pulmonary hypertension of the newborn (PPHN) occurred much more in the GBS-EOD group than the GBS-LOD group [28.4% (19/67) vs 6.9% (2/29), 13.4% (9/67) vs 0.0% (0/29), 11.9% (8/67) vs 10.3% (3/29), 4.5% (3/67) vs 0.0% (0/29), χ2=13.683, P<0.001]. (3) Among the 96 patients, 23 (24.0%) had meningitis and 73 (76.0%) developed pneumonia and sepsis. Meningitis resulted in a higher fatality rate [17.4% (4/23) vs 4.1% (3/73), χ2=4.564, P=0.035] and longer average hospital stay [(37.2±12.6) vs (14.1±5.3) d, t=7.831, P<0.001] than pneumonia and sepsis. Seven out of the 19 meningitis survivors developed intracranial complications. (4) The overall fatality rate in this study was 7.3% (7/96) and no significant difference was found between GBS-EOD and GBS-LOD group [7.5% (5/67) vs 6.9% (2/29), χ2=0.010, P=0.982]. Among the 67 GBS-EOD infants, 58 (86.6%) occurred within 24 h and five of them died, but no death was reported in the other nine cases occurred after 24 h. (5) Totally 96 strains of GBS were isolated with 100% sensitivity to penicillin, ampicillin, cefazolin and meropenem, and 97% to vancomycin. Around 79.3%-91.0% of GBS isolates were resistant to clindamycin and erythromycin. Conclusions Clinial features vary greatly in GBS-LOD and GBS-EOD cases. Infants with meningitis have poor prognosis. The drug resistance rate of GBS to erythromycin and clindamycin are relatively high. Key words: Streptococcus agalactiae; Streptococcal infections; Drug resistance, bacterial; Microbial sensitivity tests; Multicenter study