Study On The Laboratory Diagnosis And Clinical Manifestations Of Neonatal Purulent Meningitis

Objective: To improve the accuracy of early diagnoses for neonatal purulent meningitis.Methods: Based on the 16S-r RNA gene of bacteria, a pair of universal primers and a set of Gram stain-specific-probes(including Gram-positive probe and Gram-negative probe) were designed. The CSF(Cerebrospinal Fluid) specimens suspected of bacterial meningitis from the patients who were admitted to the neonatology department of Fujian province maternity and child care in 2014 were tested by Gram stain-specific-probe-based Real-time PCR assay. The tested items also include the complete blood count、CRP、blood culture、cellular of CSF、chemical parameters of CSF 、 cerebrospinal fluid culture and cerebrospinal fluid smear. Gram stain-specific-probe-based Real-time PCR assay and cerebrospinal fluid culture(and smear) were compared in the process of early diagnosis. According to the standard of the diagnosis for neonatal purulent meningitis, all the neonatal purulent meningitis cases were retrospectively studied. And the features of pre-term infants and full-term infants were compared.Results: Among the 125 cases, one case were confirmed neonatal purulent meningitis, for the GBS was cultured from its CSF and the result tested by the Gram stain-specific-probe-based Real-time PCR assay was positive.41 cases whose cellular or chemical parameters of CSF was abnormal were diagnosed as neonatal purulent meningitis. By the test of Gram stain-specific-probe-based Real-time PCR assay, 8 cases were Gram-positive and 11 cases were Gram-negative. And the other 83 cases whose CSF culture were negative and the test of Gram stain-specific-probe-based Real-time PCR assay were negative were not infected. When CSF culture served as the gold-standard of the diagnosis, the sensitivity of Gram stain-specific-probe-based Real-time PCR assay is100% and specificity is 84.6%. The positive rate of the Gram stain-specific-probe-based Real-time PCR assay is significantly higher than that of the CSF culture and smear(16% vs. 0.8%)(P<0.01). Among 42 cases, the most frequent symptoms were fever and tachypnea(52.4%).The main signs were poor response and abnormal muscle tone. The CRP of 69.1% patients increased(43% increased more than 10 times). Compared with full-term purulent meningitis group,preterm purulent meningitis group has manifestations as follows: lower birth weight, the higher rate of prolonged rupture of membranes(>18 h), earlier-onset meningitis, less fever,easier complicated with intracranial hemorrhage. Blood CRP of full-term purulent meningitis group was much higher than that of preterm purulent meningitis group.(18.1mg/L vs.1.88mg/L)(P<0.05). On the contrary, their leukocyte counts of CSF were lower than that of preterm purulent meningitis group(P<0.05).Conclusions: The symptoms and signs of neonatal purulent meningitis are atypical. To some degree, it is most probably that higher occurrence is exist neonatal purulent meningitis when the full-term infants have following symptoms: fever, increased blood c-reactive protein. Preterm patients are higher risk for neonatal purulent meningitis, when they have the history of intrauterine infection and have manifestations such as poor response, tachypnea and abnormal muscle tone. In contrast with CSF culture, the Gram stain-specific-probe-based Real-time PCR assay has following advantages: shorter time, lower price, higher sensitivity, being not affected by antibiotics etc. Combing the Gram stain-specific-probe-based Real-time PCR assay with traditional CSF culture will promote the accuracy of early diagnoses for neonatal purulent meningitis.