Characteristic | Infection rate (%)^{a} | |
---|---|---|

Single administration | Repeated administration | |

Histamine concn (M) | ||

0 | 0.0 | 0.0 |

10^{−5} | 33.3 | |

10^{−4} | 16.6 | 73.9^{b}, ^{c} |

10^{−3} | 50.0 | 50.0 |

10^{−2} | 50.0 | 66.7 |

Pn 14 concn (log CFU) | ||

4 | 0.0 | |

5 | 66.7 | |

6 | 66.7 | |

7 | 66.7 | |

8 | 73.9^{c} | |

No. of days after challenge | ||

6 | 73.9 | |

9 | 66.7 | |

12 | 16.7^{c} | |

15 | 33.3 | |

18 | 16.7^{d} | |

Pn serotype | ||

6B | 41.7^{e} | |

14 | 73.9 | |

19F | 50.0 | |

23F | 33.3 |

↵a All infection rates represent percentages of animals with Pn-positive middle ear lavages in separate groups with n being 6, unless otherwise indicated. Also, unless indicated otherwise, these results were obtained on day 6 after standard challenge procedure with Pn 14.

↵b A repeated dosage of 10

^{−4}M histamine is significantly more effective than a single dose (P < 0.05) , as calculated by a Fisher's exact test.↵c For this group, n was 24.

↵d The r

^{2}for linear correlation is 0.72; the value of P is 0.0029; both were calculated over the total measurement range of 6 to 18 days.↵e For this group, n was 12.