ANTIMICROBIAL RESISTANCE (AMR) HAS EMERGED AS A MAJOR PUBLIC HEALTH CHALLENGE. HUMAN INFECTIONS BY ANTIBIOTIC-RESISTANT PATHOGENS TRANSMITTED VIA FOOD ARE PROBLEMATIC BECAUSE THE RESISTANCE MAY COMPROMISE THE OUTCOME OF ANTIBIOTIC TREATMENT AND MAY ALSO BE ACCOMPANIED WITH INCREASED VIRULENCE, RESULTING IN ILLNESS WITH ENHANCED SEVERITY. AMR EMERGENCE, DISSEMINATION AND PERSISTENCE IN THE FOOD CHAIN REMAIN ESPECIALLY POORLY UNDERSTOOD. IN THIS PROJECT, WE WILL UTILIZE THE FOODBORNE BACTERIAL PATHOGEN CAMPYLOBACTER AS MODEL SYSTEM FOR INVESTIGATIONS THAT CAN FURTHER ELUCIDATE AMR IN AGRICULTURE. CAMPYLOBACTER IS ANNUALLY RESPONSIBLE FOR ALMOST A MILLION CASES OF ACUTE GASTROENTERITIS IN THE UNITED STATES ALONE. FURTHERMORE, IT IS THE MOST COMMON AGENT ASSOCIATED WITH THE SEVERE AUTOIMMUNE COMPLICATION GUILLAIN BARRE SYNDROME. CONTAMINATED POULTRY ARE A LEADING VEHICLE FOR CAMPYLOBACTER INFECTIONS. CAMPYLOBACTER IS NOTORIOUS FOR ITS PROPENSITY TO DEVELOP OR ACQUIRE RESISTANCE TO MULTIPLE ANTIMICROBIALS. GENES ASSOCIATED WITH AMR CAN BE READILY TRANSFERRED BY TRANSFORMATION, A PROCESS THROUGH WHICH CELLS TAKE UP DNA RELEASED FROM OTHER CELLS, AS WELL AS BY CONJUGATION, WHICH INVOLVES DIRECT CELL-TO-CELL TRANSFER OF DNA.TO INVESTIGATE AMR EMERGENCE, WE WILL USE WHOLE GENOME SEQUENCING TO IDENTIFY MUTATIONS THAT BECOME SELECTED AS CAMPYLOBACTER BECOMES EXPOSED TO INCREASING LEVELS OF ANTIBIOTICS THAT ARE FREQUENTLY EMPLOYED IN TREATMENT OF POULTRY INFECTIONS DUE TO DIVERSE AGENTS, AS WELL AS FOR TREATMENT OF HUMAN CAMPYLOBACTER INFECTIONS. WE WILL EXAMINE THE MUTATION SPECTRUM TO IDENTIFY MUTATIONS THAT MAY WORK TOGETHER IN ALLOWING RESISTANCE TO BECOME STABLE AND WELL-TOLERATED BY THE BACTERIA. WE WILL THEN EXAMINE TRANSFER OF RESISTANCE GENES BY TRANSFORMATION AND CONJUGATION FROM ONE CELL TO ANOTHER IN A CHICK MODEL SYSTEM AS WELL AS IN LABORATORY CULTURES, IN POULTRY FECES AND IN FARM WATER. FECES AND WATER SERVE AS MEDIA CRITICAL FOR TRANSFER OF CAMPYLOBACTER WITHIN POULTRY FLOCKS. WGS ANALYSIS OF SELECTED TRANSFORMANTS AND TRANSCONJUGANTS WILL BE DONE TO DETERMINE WHETHER THESE LGT EVENTS WERE ACCOMPANIED BY ADDITIONAL GENOMIC ALTERATIONS THAT STABILIZE THE ACQUIRED RESISTANCE. WE WILL ALSO EXPLORE THE IMPACT OF LOW, SUB-INHIBITORY LEVELS OF ANTIBIOTICS ON SUCH TRANSFERS OF RESISTANCE GENES. ANTIBIOTICS ARE INCREASINGLY VIEWED AS SIGNAL MOLECULES WHICH MAY HAVE PROFOUND IMPACTS ON MICROBIAL PROCESSES AT SUB-LETHAL, MINUSCULE CONCENTRATIONS THAT DO NOT THREATEN SURVIVAL OR REPLICATION OF SUSCEPTIBLE CELLS. WE WILL EXAMINE WHETHER SUCH LOW LEVELS MAY FOSTER TRANSFER OF RESISTANCE-ASSOCIATED GENES AMONG THE BACTERIA. POSITIVE IMPACTS ON TRANSFER WOULD BE HIGHLY IMPORTANT, AS ANTIMICROBIALS MAY PERSIST AT LOW, SUB-INHIBITORY LEVELS IN NUMEROUS AGRICULTURAL HABITATS AND AT SUBSTANTIAL DISTANCES FROM THE POINT WHERE THEY WERE ADMINISTERED DURING PRODUCTION, E.G. VIA MANURE, RUNOFF, FIELD-SPRAYING OR OTHER DILUTION AND DISPERSAL PROCESSES. LASTLY, WE W,ILL EXAMINE WHETHER ACQUISITION OF AMR CONFERS COMPETITIVE ADVANTAGES TO THE MICROORGANISMS' CAPACITY FOR SURVIVAL AND PERSISTENCE IN POULTRY FECES AND FARM WATER. SUCH IMPACTS WOULD ENHANCE THE RESILIENCE OF AMR IN POULTRY PRODUCTION AND IN THE NATURAL ENVIRONMENT, SINCE RESISTANT ORGANISMS WOULD BE MORE LIKELY TO REMAIN ALIVE AND BECOME TRANSFERRED TO OTHER BIRDS WITHIN A FLOCK, OR TO OTHER ANIMALS IN THE CASE OF SURFACE WATER.THE SUCCESSFUL COMPLETION OF THIS PROJECT WILL PROVIDE CURRENTLY LACKING, CRITICALLY NEEDED DATA ON PROCESSES THAT MEDIATE THE EMERGENCE, SPREAD AND RESILIENCE OF ANTIMICROBIAL RESISTANCE IN CAMPYLOBACTER, A LEADING FOODBORNE PATHOGEN. THE FINDINGS AND INSIGHTS WILL BE PERTINENT TO THIS AGENT BUT ALSO OF GENERAL AND DIRECT RELEVANCE TO AMR IN AGRICULTURE. SUCH FINDINGS AND INSIGHTS WILL FOSTER DEVELOPMENT OF SCIENCE-BASED STRATEGIES TO REDUCE ANTIMICROBIAL RESISTANCE AND ACCOMPANYING FOOD SAFETY AND PUBLIC HEALTH THREATS IN THE FOOD CHAIN. THEY ALSO ARE EXPECTED TO CONTRIBUTE TO THE DEVELOPMENT OF EVIDENCE-BASED POLICY GUIDANCE AIMING TOWARDS THE PREVENTION OR REDUCTION OF THE EMERGENCE, SPREAD AND ESTABLISHMENT OF AMR IN AGRICULTURE.