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Virulence phenotype alteration impacts nosocomial pathogen persistence on inanimate surfaces in hospital settings
Meng Zhang1, Lizhang Liu2, Xiaoqiang Yang1
1Zhejiang Key Laboratory of Medical Epigenetics, Department of Immunology and Pathogen Biology, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou 311121, China.
Abstract:
The hospital setting serves as a critical conduit for pathogen dissemination, particularly amid the escalating concern of nosocomial infections in China. Currently, most studies use metagenomics to investigate microbial communities in hospital settings, with less focus on the transmission strategies of individual bacteria. In our study, we identified two Klebsiella pneumoniae strains exhibiting different mucoid characteristics. The strain designated as KPE was obtained from a well sanitized ward, while the strain KPH was isolated from the sputum samples of patients within the identical ward. We characterized the KPE strain as not lethal to mice and showed a distinct hypomuciod phenotype, strikingly different from the virulent KPH isolate. Two strains harbored the single nucleotide polymorphism (SNP) mutations in the virulence-related gene rmpA and wcaJ promoter regions, resulting in the downregulation of mucoid regulatory gene rmpA and capsule synthesis genes. Consequently, this led to diminished production of capsular polysaccharides and weakened virulence in the KPE strain. Furthermore, the KPE strain exhibited an elevated capacity for acquiring antibiotic-resistant plasmids and greater material survival ability. These findings indicated that mucoid changes enable K. pneumoniae strains to survive better on inanimate surfaces, promoting their persistence ward environment and further transmission in patients.
Insights
Hospital-acquired Klebsiella pneumoniae strains show altered mucoid traits, impacting virulence and antibiotic resistance. Changes in capsular polysaccharide production influence bacterial survival and transmission in healthcare settings.
Area of Science:
- Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Hospital settings are key for pathogen spread, with rising nosocomial infections.
- Research often uses metagenomics, overlooking individual bacterial transmission strategies.
- Klebsiella pneumoniae is a significant nosocomial pathogen.
Purpose of the Study:
- To investigate the role of mucoid characteristics in Klebsiella pneumoniae transmission.
- To compare strains from sanitized and patient environments.
- To understand the genetic basis of altered virulence and survival.
Main Methods:
- Isolation and characterization of two Klebsiella pneumoniae strains (KPE and KPH).
- Phenotypic analysis including virulence in a mouse model and mucoid assessment.
- Genomic analysis to identify mutations in virulence-related genes (rmpA, wcaJ).
- Assessment of antibiotic resistance plasmid acquisition and material survival.
Main Results:
- Identified KPE (sanitized ward) with hypomucoid phenotype and KPH (patient sputum) with hypermucoid/virulent phenotype.
- Both strains had SNP mutations in rmpA and wcaJ promoter regions, downregulating mucoid genes.
- KPE showed reduced capsular polysaccharide production, weakened virulence, but enhanced antibiotic resistance plasmid uptake and survival on surfaces.
- KPH exhibited higher virulence.
Conclusions:
- Mucoid changes in Klebsiella pneumoniae, driven by specific mutations, affect virulence and antibiotic resistance.
- Altered mucoid phenotypes enhance bacterial survival on inanimate surfaces, aiding persistence and transmission in hospitals.
- This highlights the importance of studying individual bacterial strain characteristics for understanding nosocomial infections.
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