Prevalence of Community-Acquired, Hypervirulent Klebsiella pneumoniae Isolates in Wenzhou, China

Hypervirulent Klebsiella pneumoniae (hvKP) can cause severe invasive infections in healthy and immunocompromised individuals. It is an important clinical pathogen, with the recent identification of highly invasive community-acquired K. pneumoniae that produce purulent liver abscess. Herein, the frequency, clinical characteristics, and molecular epidemiology of K. pneumoniae isolates obtained from January to October 2016 in Wenzhou, China, were examined. In the present study, 33 isolates (68.8%, 33/48) had a positive string test and were identified as hvKP. Both age and sex were associated with a positive string test (p < 0.05). Univariate analysis revealed that liver abscess (odds ratio = 10.154) was a significant risk factor for hvKP. Among the hvKP isolates, K1 was the most common capsular serotype, followed by K2 (p < 0.05). The prevalence of K1 and K2 was significantly higher in hvKP than non-hvKP isolates. The rates of virulence-associated genes, rmpA, iroB, fib, and hib, were significantly higher for hvKP than for non-hvKP (p < 0.05). In this study, kfuB, ybtA, and wcaG were associated with K1 isolates. ST23 was the predominant hvKP type, which belonged to serotype K1. Pulsed-field gel electrophoresis showed that two clusters had >75% similarity and each accounted for >3 isolates. The homology of the 48 clinical isolates was diverse. In conclusion, hvKP isolates had a high frequency of virulence factors and a wide variety of homologs. These results suggest that, because of the toxicity associated with K. pneumoniae, increased clinical understanding of the disease is important to prevent larger, severe outbreaks.