Isolation of mammalian pathogenic bacteria using silkworms.

Area of Science:

• Microbiology
• Infectious Diseases
• Animal Models

Background:

• Predicting bacterial pathogenicity against mammals is crucial for public health.
• Existing methods for assessing bacterial virulence can be time-consuming and resource-intensive.
• A rapid and reliable in vivo model is needed to screen bacterial strains for potential mammalian pathogenicity.

Purpose of the Study:

• To develop and validate a method for predicting bacterial pathogenicity in mammals.
• To utilize silkworm (Bombyx mori) virulence as a proxy for mammalian pathogenicity.
• To identify novel bacterial pathogens of mammals.

Main Methods:

• Isolated 122 bacterial strains from fish and shellfish intestines.
• Assessed bacterial virulence by injecting cultures into silkworm hemolymph at 37°C.
• Correlated silkworm lethality with mouse lethality for highly virulent strains.

Main Results:

• Fifty bacterial strains demonstrated significant lethality (>50%) in silkworms.
• Ten strains with the highest silkworm pathogenicity were further tested in mice.
• Eight of these ten strains killed mice within 4 days, including Staphylococcus simiae and Staphylococcus pasteuri, previously unreported mammalian pathogens.

Conclusions:

• Silkworm virulence assays at 37°C can effectively predict bacterial pathogenicity against mammals.
• This method offers a rapid and cost-effective approach for screening bacterial strains.
• The study identified new potential mammalian pathogens, highlighting the utility of the silkworm model.