The early dynamics study of cerebrospinal fluid bacterial in a rabbit model of bacterial meningitis / 中华传染病杂志

ABSTRACT

Objective To study the dynamics changes of cerebrospinal fluid (CSF) bacterial load within 48 h after infection in a rabbit meningitis model, and provide information for diagnosis,treatment and prognosis of this disease. Methods Taking New Zealand white rabbit as the study object, meningitis model was established via cerebellar cistern puncture with different concentrations of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) to explore the relationship between the mortality of animals and the subarachnoid inoculation dosage. The dynamics study of CSF bacterial load was conducted with proper inoculation bacterial dosage. Forty-eight rabbits were separated into four groups (12 each group) E. coli meningitis model group, E. coli meningitis + ceftriaxone treated group, S. aureus meningitis model group and S. aureus meningitis + vancomycin treated group. At 0,12, 24, 36 and 48 h of inoculation, CSF and blood samples were obtained for CSF bacterial quantitative culture, CSF leukocyte count and peripheral blood leukocyte count. Finally, the relationships between the early mortality of animals, the efficacy of antibiotics, CSF leukocyte counts and the dynamics changes of CSF bacterial load were analyzed in the bacterial meningitis rabbit model.The CSF bacterial load and the white blood cell count curve were compared by analysis of covariance (ANOVA). Correlation test was done using correlate partial analysis. Results The relationship between subarachnoid inoculation dosage and the mortality of rabbits presented S-curve correlation.The bacterial load in subarachnoid space peaked in 12-24 h after infection and then gradually decreased. Effective antibiotic therapy could significantly speed up the decline of this process. There were significantly different between E. coli meningitis model group and E. coli meningitis+ceftriaxone treated group (F= 27. 10, P<0. 01), between S. aureus meningitis model group and S. aureus meningitis + vancomycin treated group (F=5. 97, P = 0. 016). There was a positive correlation between CSF bacterial load and CSF leukocyte count in E. coli and S. aureus meningitis model groups (r=0. 89, 0.84, respectively; P = 0.046, 0.049, respectively). Conclusions In the treatment of bacterial meningitis, effective and sufficient antibiotics should be used as soon as possible to control the CSF bacterial load and reduce the mortality. The CSF leukocyte count can be used as indicator of CSF bacterial load and guide the antibiotic treatment in clinical bacterial meningitis.