The pathogenicity of <i>rmpA</i> or aerobactin-positive <i>Klebsiella pneumoniae</i> 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.