Methods and compositions to prevent microbial infection

A synthetic organism comprising a recombinant nucleotide comprising

• at least one kill switch molecular modification comprising
• a first cell death gene operatively associated with
• a first regulatory region comprising an inducible first promoter, wherein
• the inducible first promoter exhibits conditionally high level gene expression of the recombinant nucleotide in response to exposure to blood, serum, or plasma of at least three fold increase of basal productivity as determined
• before and from 30 minutes to 180 minutes after the exposure to blood, serum, or plasma by quantitative polymerase chain reaction (qPCR) or RNA sequencing (RNAseq),
• wherein the synthetic microorganism is derived from a Staphylococcus aureus strain,
• wherein the at least one kill switch molecular modification is integrated to a chromosome of the synthetic microorganism,
• and
• wherein the first cell death gene comprises an sprA1 gene comprising the nucleotide sequence of SEQ ID NO:
• 284.