PLASMID PROFILES AND RESISTANCE TO ANTIMICROBIAL AGENTS AMONG SALMONELLA-ENTERITIDIS ISOLATES FROM HUMAN-BEINGS AND POULTRY IN THE MIDWESTERN UNITED-STATES

In the study reported here, 121 Salmonella enteritidis isolates from h uman beings and 467 isolates from nonhuman sources were analyzed for p lasmid pattern and susceptibility to a panel of antimicrobial agents c ommonly used as biologic markers. A significant (P < 0.05) number of i solates from nonhuman sources were resistant to p-lactam antibiotics a nd tetracycline. Resistance to aminoglycosides, quinolones, and trimet hoprim/sulfamethoxazole was uncommon. Of the 588 isolates, 445 (76%) w ere resistant to 2 or move antimicrobial agents. Sixty of 121 (50%) S enteritidis isolates from human beings were susceptible to all 12 anti microbial agents, but 425 of 467 (91%) S enteritidis isolates from non human sources expressed resistance to 1 or move of the antimicrobial a gents used in the study Analysis of plasmid profiles revealed that sig nificantly (P < 0.05) move isolates from nonhuman sources had high mol ecular weight plasmids than did isolates from human beings. Isolates f rom ceca of chickens were associated with patterns of low molecular we ight plasmids. Analysis of results of the study revealed similarities among S enteritidis from human beings and eggs, as determined on the b asis of plasmid profiles and antibiotic susceptibility patterns, which may implicate eggs as one of the potential sources for infection of h uman beings. In addition, periodic monitoring of a substantial number of Salmonella isolates to detect drug resistance may be a prudent prac tice for use in revising the list of antimicrobial agents commonly use d in human beings and other animals.