Klebsiella aerogenes strain:KA1 Genome sequencing and assembly. Klebsiella aerogenes strain:KA1

Antibiotic resistance against human pathogenic bacteria is a global problem and the issue is becoming more serious day-by-day. Klebsiella aerogenes (formerly known as Enterobacter aerogenes), a Gram-negative opportunistic human pathogen, is usually found in soil and water, but there are increasing number of reports in recent years on isolation of antibiotic-resistant strains of K. aerogenes. Here, we found that a foodborne K. aerogenes strain can kill the larvae of the silk moth, Bombyx mori within 72 h after injection into the hemolymph (blood) or midgut, although no death was observed upon injection with Escherichia coli DH5alpha, a laboratory strain. Significant bacterial load of K. aerogenes in the hemolymph was observed within 18 h of infection along with more than 50 percent death of hemocytes. Whole genome sequencing analysis revealed that the K. aerogenes strain harbors a number of virulence genes including ompA, entA, entB, yagW/ecpD, iroN. Although the strain showed resistance to ampicillin in vitro among the antibiotics tested, it showed sensitivity to ampicillin in the Bombyx larvae infection model. When we injected aqueous extracts of hog plum or Indian gooseberry into the midgut of larvae prior to K. aerogenes infection, the larval survival rate was around 75 percent after 72 h. These results indicate that the large body size of Bombyx larvae can be taken advantage of for the direct injection of biological extracts into the midgut to rapidly screen for extracts with antibacterial effect against human pathogenic bacteria like K. aerogenes.