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Objective:To evaluate diagnostic performance of Todd-Hewitt (T-H) broth culture method, direct culture method, liquid chromogenic culture method, and loop-mediated isothermal amplification (LAMP) method for screening group B streptococcus (GBS) during late pregnancy.Methods:In the retrospective study, the rectal vaginal secretions samples were collected from pregnant women at 35 to 37 weeks at the obstetrics clinic of Guangzhou Women and Children′s Medical Center affiliated to Guangzhou Medical University during October 2016 to April 2018. For the purposes of clinical evaluation, T-H broth culture was used as the standard reference method, and double-blind trials were used to evaluate diagnostic performance of direct culture method, liquid chromogenic culture method, and LAMP method for screening group B streptococcus during late pregnancy in three research stages. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), coincidence rate and Yoden index for each method were calculated. Also, the level of agreement between each method and T-H broth was assessed using the kappa (k) coefficient.Results:A total of 969 specimens were detected by the T-H enrichment culture method, and 90 were positive (9.3%). The sensitivities from high to low were LAMP method [100% (25/25)], direct culture method [81.5% (22/27), 95 %CI:65.8%-97.1%], and liquid color culture method [71.1% (27/38), 95 %CI:55.9%-86.2%]. Specificities were direct culture method [100% (282/282)], liquid color culture method [98.1% (455/464), 95 %CI:96.8%-99.3%], and LAMP method [94.0% (125/133), 95 %CI: 89.9%-98.1%]. The coincidence rates were direct culture method [98.4% (22+282)/309], liquid color culture method [96.0% (27+455)/502], and LAMP method [94.9% (25+125)/158]. The Kappa values of the direct culture method (0.889), LAMP method (0.832) and the enrichment culture method were all ≥0.75, and that of the liquid color culture method was 0.708. The false negative rate of direct culture method was 18.5% (5/27), and no false negative case by LAMP method, but its false positive rate was 6.0% (8/133). The false negative rate and false positive rate of liquid color culture method were 28.9% (11/38) and 1.9% (9/464), respectively. Conclusions:Of the three screening methods compared in this study, only the LAMP method has the advantages in sensitivity, specificity, and coincidence rate compared with T-H enriched culture method, while the others have a certain degree of false negatives rate. The clinical laboratory can introduce these methods based on laboratory facilities and staffing, or refer to the European and American guidelines and combine the recommended antenatal GBS screening method with intrapartum nucleic acid amplification tests to best meet the clinical demands.
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Objective@#To evaluate diagnostic performance of Todd-Hewitt (T-H) broth culture method, direct culture method, liquid chromogenic culture method, and loop-mediated isothermal amplification (LAMP) method for screening group B streptococcus (GBS) during late pregnancy.@*Methods@#In the retrospective study, the rectal vaginal secretions samples were collected from pregnant women at 35 to 37 weeks at the obstetrics clinic of Guangzhou Women and Children′s Medical Center affiliated to Guangzhou Medical University during October 2016 to April 2018. For the purposes of clinical evaluation, T-H broth culture was used as the standard reference method, and double-blind trials were used to evaluate diagnostic performance of direct culture method, liquid chromogenic culture method, and LAMP method for screening group B streptococcus during late pregnancy in three research stages. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), coincidence rate and Yoden index for each method were calculated. Also, the level of agreement between each method and T-H broth was assessed using the kappa (k) coefficient.@*Results@#A total of 969 specimens were detected by the T-H enrichment culture method, and 90 were positive (9.3%). The sensitivities from high to low were LAMP method [100% (25/25)], direct culture method [81.5% (22/27), 95%CI:65.8%-97.1%], and liquid color culture method [71.1% (27/38), 95%CI:55.9%-86.2%]. Specificities were direct culture method [100% (282/282)], liquid color culture method [98.1% (455/464), 95%CI:96.8%-99.3%], and LAMP method [94.0% (125/133), 95%CI: 89.9%-98.1%]. The coincidence rates were direct culture method [98.4% (22+282)/309], liquid color culture method [96.0% (27+455)/502], and LAMP method [94.9% (25+125)/158]. The Kappa values of the direct culture method (0.889), LAMP method (0.832) and the enrichment culture method were all ≥0.75, and that of the liquid color culture method was 0.708. The false negative rate of direct culture method was 18.5% (5/27), and no false negative case by LAMP method, but its false positive rate was 6.0% (8/133). The false negative rate and false positive rate of liquid color culture method were 28.9% (11/38) and 1.9% (9/464), respectively.@*Conclusions@#Of the three screening methods compared in this study, only the LAMP method has the advantages in sensitivity, specificity, and coincidence rate compared with T-H enriched culture method, while the others have a certain degree of false negatives rate. The clinical laboratory can introduce these methods based on laboratory facilities and staffing, or refer to the European and American guidelines and combine the recommended antenatal GBS screening method with intrapartum nucleic acid amplification tests to best meet the clinical demands.
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Objective To raise awareness of the late-onset meningitis caused by group B streptococcus (GBS) which was homogenous to the maternal colonization.Methods The clinical data of late-onset GBS meningitis in neonates twins whose pathogens were homogenous to their maternal colonization were collected from Department of Neonatology,Guangzhou Women and Children's Medical Center.The general conditions,clinical symptoms,laboratory tests and drug treatment of the twins and their mother were retrospectively analyzed,and the GBS homology during inpatient care was tested.And the progress of the twins' condition was investigated by telephone follow-up.Results The mother had two pregnancies without prenatal GBS screening or intrapartum antimicrobial intervention for GBS,everything was normal during pregnancy and delivery.Twins were born through cesarean section.The elder sister was discharged with Linezolid taken orally after 167 days in hospital without convulsions,shaking or other discomfort.The elder sister was followed up for every 2 weeks,and in the last time of follow-up,cerebrospinal fluid white blood cell counts were 45 × 106/L,protein level was 1.52 g/L and Linezolid was withdrawn.The younger brother was discharged after 58 days in hospital with follow-up for every 2 weeks,and in the last time of follow-up,cerebrospinal fluid white blood cell counts were 30 × 106/L,protein level was 0.66 g/L.During the hospitalization and follow-up without convulsions and irritation,and the cranial magnetic resonance imaging of the twin brother was normal.Test results showed that the GBS bacteria strain for twins and their mother were all serotype Ⅲ.The possibility of the GBS homology was more than 90％.Conclusions The toxicity of serotype Ⅲ GBS strain was strong.More proactive precautions should be considered to apply for the mother whose first birth already had GBS infection.Early identification and intervention of infection risk factors would help optimize the anti-infection treatment program and reduce nerve system damage and other adverse outcomes caused by invasive GBS infection.
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Objective To investigate the clinical characteristics,antibiotic susceptibilities and serotypes of Group B Streptococcus(GBS)isolated from neonatal meningitis to provide references for the prevention and treatment of neonatal GBS meningitis. Methods From June 2013 to June 2016,we surveyed the GBS strains iso-lated from purulent meningitis of < 90 days infants from Guangzhou Women and Children′s Medical Center. The GBS isolates were identified and the minimum inhibitory concentration of the antibiotics was determined by Vitek 2 Compact automatic bacterial identification system.GBS serotyping was performed using Strep-B-Latex?rapid latex agglutination test kit. Results A total of 46 cases of neonatal GBS meningitis,15 cases of early-onset infection and 31 cases of late-onset infection were diagnosed. 78.3% of GBS meningitis with varying degrees of complica-tions.Among 41 survivors with 3~24 months follow-up,50% of the early-onset and 44.8% of the late-onset GBS meningitis with varying degrees of neurological sequelae.Four capsular types were identified among the 46 isolates, serotype-Ⅲwas the most prevalent(73.9%),followed by Ib(19.6%),V(4.3%)and Ia(2.2%).All the isolates were susceptible to penicillins,cephalosporins,linezolid and vancomycin. Conclusion The highly pathogenic serotype-Ⅲ was the predominant serotype among neonatal GBS meningitis in Guangzhou,Therefore,it is neces-sary to strengthen the epidemiological surveillance of GBS invasive infection and the effective implementation of pre-ventive measures.