The role of Klebsiella pneumoniae rmpA in capsular polysaccharide synthesis and virulence revisited

• Published in: Microbiology (Society for General Microbiology) 2011-12, Vol.157 (Pt 12), p.3446-3457
• Main Authors: HSU, Chun-Ru, LIN, Tzu-Lung, CHEN, You-Ci, CHOU, Huei-Chi, WANG, Jin-Town
• Format: Article
• Language: English
• Subjects: Animals; Bacterial Capsules - biosynthesis; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Disease Models, Animal; Female; Fundamental and applied biological sciences. Psychology; Gene Deletion; Genetic Complementation Test; Humans; Klebsiella Infections - microbiology; Klebsiella Infections - mortality; Klebsiella Infections - pathology; Klebsiella pneumoniae; Klebsiella pneumoniae - metabolism; Klebsiella pneumoniae - pathogenicity; Mice; Mice, Inbred BALB C; Microbiology; Miscellaneous; Survival Analysis; Virulence; Virulence Factors - metabolism
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.050336-0

Klebsiella pneumoniae community-acquired pyogenic liver abscess (PLA) is an emerging infectious disease. The rmpA gene (for regulator of mucoid phenotype A) has been reported to be associated with PLA in prevalence studies. NTUH-K2044, a K1 PLA isolate, carries three rmpA/A2 genes: two large-plasmid-carried genes (p-rmpA and p-rmpA2) and one chromosomal gene (c-rmpA). In this study, we re-examined the role of rmpA/A2 in PLA pathogenesis to clarify the relationship of rmpA/A2 and capsular serotype to virulence. Using isogenic gene deletion strains and complemented strains of NTUH-K2044, we demonstrated that only p-rmpA enhanced expression of capsular polysaccharide synthesis (cps) genes and capsule production. Nevertheless, the lethal dose and in vivo competitive index indicated that p-rmpA does not promote virulence in mice. The prevalence of these three rmpA/A2 and capsular types in 206 strains was investigated. This revealed a correlation of rmpA/A2 with six PLA-related capsular types (K1, K2, K5, K54, K57 and KN1). However, the correlation of rmpA/A2 with K1 strains from the West was less obvious than with the strains from Asia (17/22 vs 39/39, P = 0.0019). Among the three rmpA/A2 genes, p-rmpA was the most prevalent. Due to the strong correlation with PLA-related capsular types, p-rmpA could serve as a surrogate marker for PLA. We found an association of p-rmpA with three widely spaced loci in a large plasmid (30/32). Therefore, rmpA could be co-inherited together with virulence genes carried by this plasmid.