Establishment of a murine model of Acinetobacter baumannii pneumonia with a new intubation method / 中国感染与化疗杂志

ABSTRACT

Objective To construct a new intubation method with an otoscope and establish a murine model of Acinetobacter baumannii pneumonia with this method.Methods Part IThe Hallowell Intubation Pack for mice (Braintree Scientific Inc., USA)was used to construct a new intubation method with an otoscope.Part IITwenty-four female ICR mice were randomized into 3 groups including control (group 1),immunosuppression (group 2)and infection after immunosuppression groups (group 3),with 8 mice in each group.The mice were treated with cyclophosphamide (CTX)by peritoneal injection to posterior orbital venous plexus.The total number of white blood cells,the number of neutrophils and the percentage of neutrophils were determined.Four mice were sacrificed at 0 h and 48 h after inoculation in each group.Then the lungs from each mouse were aseptically collected for quantitative culture and histopathology.Results Part ITen mice were successfully intubated using the new method and none of the mice was dead.Pulmonary bacterial culture at baseline (0 h)was (2.91×107-5.32×107 )CFU/g tissue,while the mean± standard deviation was (4.05 × 107 ± 0.82 × 107 )CFU/g tissue.The results showed that this new method had a perfect repeatability.Part IIOver 48 h,2 mice were dead in group 3,while no mouse was dead in other 2 groups.For group 3,the average pulmonary bacterial culture was 4.13×107 CFU/g tissue at 0 h and reached 3.62×1010 CFU/g tissue at 48 h (increased appropriate 1 000 times,P <0.01).The histopathologic changes in lung showed local granulomas and abscess in the alveolar space.Conclusions Intubation under the guidance of otoscope had the advantages of high repeatability and easy to operate.Additionally,the method provided stable and consistent bacterial inocula into lungs.The murine model of Acinetobacter baumannii pneumonia was successfully established with a new intubation method under the guidance of otoscope.