The histopathological features and bacterial counts after exposure to Streptococcus pneumoniae serotypes 2,3,4 and 19 F in the lung of Balb/c mice

Background: Pneumococci cause mild or severe infections that begin with colonization in the nasopharyngeal area. Intranasal transmission is a natural route of bacterial infection in the host. This study aims to determine the type of serotype that can infect and provide an overview of inflammation in the lungs of mice after exposure to 107 bacteria S. pneumoniae serotypes 2, 3, 4, 19F and ATCC 6030 intranasally in animals try Balb / c mice. Methods: True experimental study was conducted using Randomized Posttest Only Control Group Design among 30 Balb/c mice divided into 3 groups. The intervention used in this study was carried out twice, namely at 24 hours and 48 hours with 50 ?l suspension of Streptococcus pneumoniae bacterial inoculum via intranasal drop by drop. Lung histopathology and CFU analysis of infected mice were evaluated. TNF-? was examined using ELISA. Data were analyzed using SPSS software version 17 for windows. Results: The results showed that S. pneumoniae serotype 3 could infect Balb / c mice and found about 5x104 CFU (SD ± 7x104 CFU) at 101 dilutions and was still detected at 104 dilutions i.e. 0.5 CFU (SD ± 0.7 CFU) at 24 hours post-infection as well at 48 hours postinfection, accompanied by infiltration of neutrophil cells in the lung tissue at the same time. The TNF-? levels did not significantly differ between the treatment group (P>0.05) Conclusion: The results of this study indicate that not all S. pneumoniae serotypes can infect experimental animals. Keywords: Animal models, Intranasal challenge, Streptococcus pneumoniae, Colony Forming Unit/CFU