A comparative study of induction of pneumonia in mice with planktonic and biofilm cells of Klebsiella pneumoniae

Sex-dependent vulnerability for Wistar rats model following intranasal instillation with Klebsiella pneumoniae ATCC 43816 causing lobar pneumonia

BACKGROUND

Klebsiella pneumoniae has become one of the major threats to public health as it causes nosocomial and community-acquired infections like lobar pneumonia. This infection causes acute inflammation in the lung, characterized by the recruitment of polymorphonuclear cells, generating free radicals, and decreasing the endogenous antioxidant balance system. Many experimental studies have focused on the induction, progression and resolution of infection up to its peak, but these documented processes remain highly random and their sex dependence un-elicited. These fluctuations of physiopathological parameters would impact disease progression depending on the animal's model and bacterial strain used. The present study investigated the sex-dependent vulnerability of Wistar rats to K. pneumoniae ATCC 43816 lobar pneumonia induced by the intranasal instillation method.

METHODS

Experimental pneumonia was induced by K. pneumoniae ATCC 43816 in male and female Wistar rats following intranasal instillation. The physiopathogenesis of the disease was studied by bacteriological and histopathological exams, histomorphometric analysis of the blood and/or lung tissue, and body weight loss in infected animals. In addition, the overall severity of lesions was determined by the total score obtained by averaging the individual scores from the same group of animals.

RESULTS

The K. pneumoniae ATCC 43816 strain showed inoculation dose-, incubation time of the disease- and sex-dependent- differences in its ability to induce lobar pneumonia. Evaluation of different parameters showed that the disease peaked on day 15 post-inoculation, with more pathogenic effects on female rats. This observed sex-dependence difference in Wistar rats was mainly highlighted by the determined lethal dose 50 (LD50), bacterial load count in whole blood and lung tissues, body weight loss, inflammatory granulomas forming and diffuse alveolar damages. The pathogenicity was confirmed by scoring the severity of pathologic lesions of lung tissues.

CONCLUSIONS

The results obtained highlighted the gender-dependency in the physiopathogenesis processes of K. pneumoniae ATCC 43816 induced-lobar pneumonia, in Wistar rats. Female Wistar rats' susceptibility is useful in studying pathology and in preclinical trial investigations of new treatments for infectious pneumonia.

Isolation and Characterization of Aquatic-Borne Klebsiella pneumoniae from Tropical Estuaries in Malaysia

Klebsiella pneumoniae is an opportunistic pathogen that is responsible for causing nosocomial and community-acquired infections. Despite its common presence in soil and aquatic environments, the virulence potential of K. pneumoniae isolates of environmental origin is largely unknown. Hence, in this study, K. pneumoniae isolated from the estuarine waters and sediments of the Matang mangrove estuary were screened for potential virulence characteristics: antibiotic susceptibility, morphotype on Congo red agar, biofilm formation, presence of exopolysaccharide and capsule, possession of virulence genes (fimH, magA, ugE, wabG and rmpA) and their genomic fingerprints. A total of 55 strains of K. pneumoniae were isolated from both human-distributed sites (located along Sangga Besar River) and control sites (located along Selinsing River) where less human activity was observed, indicated that K. pneumoniae is ubiquitous in the environment. However, the detection of potentially virulent strains at the downstream of Kuala Sepetang village has suggested an anthropogenic contamination source. In conclusion, the findings from this study indicate that the Matang mangrove estuary could harbor potentially pathogenic K. pneumoniae with risk to public health. More studies are required to compare the environmental K. pneumoniae strains with the community-acquired K. pneumoniae strains.