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Updated: Jul 22, 2025
A Non-invasive and Technically Non-intensive Method for Induction and Phenotyping of Experimental Bacterial Pneumonia in Mice
Published on: September 28, 2016
Immune Response And Pathophysiological Features Of Klebsiella Pneumoniae In Mice
Nasma Maged Elemary1, Mohamed Mahrous Emara2, Amin Abd Elhady Tahoun3
1Department of Microbiology and Immunology, Kafrelsheikh University,Egypt.
Objectives:
To assess the bacterial colonisation of mice organs and faeces infected with 3 strains of Klebsiella pneumoniae, to measure levels of tumour necrosisfactor-alpha, tumour necrosisfactor-beta and interleukin-6 in mice serum, and to evaluate immune response of mice infected with Klebsiella pneumoniae.
Method:
The animalstudy was conducted at Kafreslsheikh University, Egypt, in 2021, and comprised mice 5-7 weeks old who were infected with 3 strains of Klebsiella pneumoniae; K80uge+ (uri, kfu+, mrkD+; K68 gyrA+(gyrase A), mrkD+; and K84 uge+, kfu+, mrkD+". They were monitored for 14 days. The bacterial colonisation of mice livers, lungs, spleens and faeces were determined using culture on MacConkey agar. The percentage of neutrophils detected as cluster of differentiation 11b+ and cluster of differentiation 45+ in the mice serum was determined by flow cytometry. Levels of tumour necrosis factor-alpha and tumour necrosis factor-beta were measured using enzyme-linked immunosorbent assay.
Results:
There were 4 sets of female mice [1 control and 3 infected groups for which 3 K. pneumoniae strains (K80 uge+, kfu+, mrkD+; K68 gyrA+, mrkD+; and K84 "uge+, kfu+, mrkD+)] weighing 13-24gm was used. Colonisation of mice organs and faeces was high after 24 hours then declined rapidly after 3 days, 10 days and 14 days in case of infection with capsulated and non-capsulated strains of bacteria. Livers, lungs and spleens showed maximum inflammation after 24 hours, then declined rapidly. Both cytokine production and organ inflammation increased after one day of infection. There was a significant correlation between the produced cytokines and histopathological changesin liver, lung and spleen. The neutrophils increase in case of infection with K84 and K80 was more than non-capsulated K68.
Conclusions:
Neutrophils were found to play an important role in the clearance and treatment of Klebsiella pneumoniae.
Insights
This study shows neutrophils are key to clearing Klebsiella pneumoniae infections in mice. Increased neutrophils correlated with reduced bacterial colonization and organ inflammation, aiding infection control.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Klebsiella pneumoniae is a significant opportunistic pathogen.
- Understanding host immune responses is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the bacterial colonization of mice organs and feces after infection with Klebsiella pneumoniae.
- To measure key inflammatory cytokine levels (tumor necrosis factor-alpha, tumor necrosis factor-beta, interleukin-6) in mice serum.
- To evaluate the overall immune response, focusing on neutrophil activity, during Klebsiella pneumoniae infection.
Main Methods:
- Infection of mice (5-7 weeks old) with three distinct Klebsiella pneumoniae strains.
- Monitoring bacterial colonization in liver, lungs, spleen, and feces using MacConkey agar.
- Quantification of neutrophils (CD11b+, CD45+) via flow cytometry.
- Measurement of cytokine levels using enzyme-linked immunosorbent assay (ELISA).
Main Results:
- Bacterial colonization peaked at 24 hours post-infection, declining over 14 days.
- Organ inflammation (liver, lungs, spleen) and cytokine production increased significantly within one day.
- A strong correlation was observed between cytokine levels and histopathological changes.
- Neutrophil levels were higher in infections with encapsulated strains (K80, K84) compared to the non-encapsulated strain (K68).
Conclusions:
- Neutrophils play a critical role in the host's defense against Klebsiella pneumoniae.
- The findings highlight neutrophils' importance in bacterial clearance and infection resolution.
