The pathogenicity of rmpA or aerobactin-positive Klebsiella pneumoniae in infected mice

OBJECTIVES: To investigate the pathogenicity of Klebsiella pneumoniae (KPN) possessing rmpA or the aerobactin gene in infected mice. METHODS: BALB/c mice were divided into four groups (n = 10 per group) and infected with: string test-positive and rmpA-positive or aerobactin-positive KPN (group 1), string test-negative but rmpA-positive KPN (group 2), string test-negative but aerobactin-positive KPN (group 3), or string test- and rmpA/aerobactin-negative KPN (group 4). Mouse survival time was compared among groups, and the infection of livers, spleens, lungs, and kidneys and KPN growth were assessed in infected mice. RESULTS: Compared with the negative group (group 4), the survival rates of mice infected with rmpA- or aerobactin-positive KPN (groups 1–3) were significantly lower, their multi-organ injuries were significantly more severe, and bacterial enumeration was significantly higher. CONCLUSIONS: Despite being string test-negative, aerobactin- or rmpA-positive KPN still exhibit high virulence and anti-immune effect activity. Therefore, the combination of the string test and gene detection of aerobactin and rmpA will be helpful in screening hypervirulent KPN.