Clearance of Escherichia Coli from the Gut of German Cockroaches is Dependent on Host Developmental Stage and Influenced by the Gut Microbiota

The German cockroach, Blatella germanica, is a suspected vector of several enteric bacterial pathogens. However, little is known about the dynamics of bacterial transmission by these insects. Here, we orally infected B. germanica with various laboratory and field strains of Escherichia coli and examined the persistence of the bacteria in the cockroach gut over time. Our results reveal that a laboratory strain of E. coli is largely cleared within 48 hours while some field isolates can persist at appreciable levels for longer than 3 days and reduce cockroach longevity. We also find that the ability to clear some strains of E. coli differs between cockroach nymphs and adults. Notably, no differential expression of the antimicrobial gene lysozyme was observed in any infected groups. However, clearance of E. coli was significantly reduced in gnotobiotic cockroaches that were reared in the absence of environmental bacteria, suggesting a protective role for the microbiota against exogenous bacterial pathogens. Together, these results demonstrate that the interactions between cockroaches and bacterial pathogens are highly dynamic and influenced by a combination of microbial, host, and environmental parameters