Relationship between the inoculum dose of Streptococcus pneumoniae and pneumonia onset in a rabbit model
Relationship between the inoculum dose of Streptococcus pneumoniae and pneumonia onset in a rabbit model
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DOI：
10.1183/09031936.05.00091904
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发表时间：
2005-04-01
影响因子：
24.3
通讯作者：
Dubick, MA
中科院分区：
文献类型：
--
作者：
Yershov, AL;Jordan, BS;Dubick, MA
一般认为，当吸入或吸出的病原体的剂量超过呼吸道宿主防御系统时，细菌性肺炎的发展成为可能，但这一假设尚未在临床或实验上得到验证。并估计了导致健康新西兰白色兔肺炎的中位有效剂量（平均值+/- SD 4.75 +/- 0.25 kg（n=27））。家兔支气管内接种递增剂量的肺炎链球菌，在随后的96 h内观察到肺炎发作。诊断方法是基于临床肺部感染评分，修改后用于兔。在> 4.60 log（10）cfu的剂量下，肺炎杆菌可使兔中肺炎的发展更可预测（高达90%）。较低剂量的细菌在80%的接种动物中没有引起肺炎。通过逻辑回归、概率单位分析和Reed-Muench法估计了中位有效剂量，分别为4.32、4.38和4.67 log（10）cfu，推测当接种剂量超过抗菌保护阈值时，更可能发生肺炎球菌肺炎，使接种剂量成为疾病发作的危险因素。
It is generally assumed that the development of bacterial pneumonia becomes possible when the dose of inhaled or aspirated pathogens overwhelms the respiratory tract host defence system, but this hypothesis has not yet been tested either clinically or experimentally.This study evaluated inoculum dose in relation to onset of experimental pneumococcal pneumonia, and estimated the median effective dose resulting in pneumonia in healthy New Zealand White rabbits (mean +/- SD 4.75 +/- 0.25 kg (n=27)). Rabbits were endobronchially inoculated with increasing doses of Streptococcus pneumoniae and pneumonia onset was observed over the following 96 h. The diagnostic approach was based on the Clinical Pulmonary Infection Score, modified for use in rabbits.Inoculation of S. pneumoniae at doses of > 4.60 log(10) cfu made the development of pneumonia in rabbits more predictable (up to 90 %). Lower doses of bacteria failed to cause pneumonia in 80 % of inoculated animals. The median effective dose was estimated by means of logistical regression, probit analyses and the Reed-Muench method, and corresponded to 4.32, 4.38 and 4.67 log(10) cfu, respectively.It is speculated that development of pneumococcal pneumonia becomes more likely when the inoculum dose exceeds a threshold of antibacterial protection, making inoculum dose a risk factor for disease onset.