Iizawa Y, Kitamoto N, Hiroe K, Nakao M
Pharmaceutical Research Laboratories III, Pharmaceutical Research Division, Takeda Chemical Industries Ltd, Osaka, Japan.
J Med Microbiol. 1996 Jun;44(6):490-5. doi: 10.1099/00222615-44-6-490.
A model of persistent colonisation in the nasal cavity of mice by Streptococcus pneumoniae has been established. S. pneumoniae NNP-4 was introduced to the lungs of CBA/J mice at a density of c. 10(4) cfu/lung by an aerosol method and a high dose of ampicillin was administered 1 h after infection. This antibiotic eliminated bacteria from the lungs and trachea, but did not affect the bacterial counts in the nasal cavity. In mice given ampicillin, the bacteria were recovered from the nasal cavity only more than 2 weeks after infection, but IgG antibody against the colonising organisms was produced in sera around day 8 after infection. Airway obstruction was induced by intratracheal injection of formalin 2% into mice. Organisms appeared in the lungs in greater numbers when formalin was injected before the antibody production than when the immunity was established. In the early stages of infection, 10(3)-10(4) cfu appeared in the lungs 6 h after the formalin injection and the bacterial counts increased to c. 10(6) cfu within 24 h. When ampicillin was administered again 1 h after formalin was given, no bacteria were recovered from lungs 6 h later. However, in some of the mice given ampicillin after formalin, bacteria appeared in the lungs on the next day and the bacterial counts increased thereafter. These results suggest that S. pneumoniae in the nasal cavity invade the lower respiratory tract and that these organisms can localise and proliferate in lungs in the event of damage to the airway.
已经建立了肺炎链球菌在小鼠鼻腔持续定植的模型。通过气溶胶法将肺炎链球菌NNP - 4以约10⁴ cfu/肺的密度引入CBA/J小鼠的肺部，并在感染后1小时给予高剂量氨苄西林。这种抗生素清除了肺部和气管中的细菌，但不影响鼻腔中的细菌数量。在给予氨苄西林的小鼠中，细菌仅在感染后2周多从鼻腔中重新出现，但在感染后约第8天血清中产生了针对定植菌的IgG抗体。通过向小鼠气管内注射2%福尔马林诱导气道阻塞。在抗体产生前注射福尔马林时，肺部出现的细菌数量比建立免疫时更多。在感染的早期阶段，注射福尔马林后6小时，肺部出现10³ - 10⁴ cfu，细菌数量在24小时内增加到约10⁶ cfu。当在给予福尔马林后1小时再次给予氨苄西林时，6小时后肺部未检出细菌。然而，在一些福尔马林后给予氨苄西林的小鼠中，第二天肺部出现细菌，此后细菌数量增加。这些结果表明，鼻腔中的肺炎链球菌侵入下呼吸道，并且在气道受损时这些细菌能够在肺部定位并增殖。
