Cephalosporin-resistant Escherichia coli among Summer Camp Attendees with Salmonellosis

led to the detection of Salmonella enterica and extended-spectrum cephalosporin-resistant Escherichia coli (ESCREC). Stool cultures were performed for 22 symptomatic campers, three asymptomatic food handlers, and 10 healthy household members. Of the 22 campers, 19 had Salmonella enterica, 9 had an ESCREC strain carrying an extended-spectrum β-lactamase, and 2 had a second ESCREC strain carrying a plasmidic cephamycinase. Related ESCREC were detected in two (salmonella-negative) asymptomatic food handlers and in none of the healthy household members. Fecal ESCREC and its β-lactamases and plasmids were extensively characterized. Three of the five ESCREC clones were recovered from multiple hosts. The apparent dissemination of ESCREC suggests a food or water vehicle. The observed distribution of resistance plasmids and β-lactamase genes in several clones indicates a high degree of horizontal transfer. Heightened vigilance and increased efforts must be made to discover the reservoirs and vehicles for community dissemination of ESCREC. S trains of Escherichia coli that produce enzymes capable of degrading extended-spectrum cephalosporins (ESCs), i.e., extended-spectrum β-lactamases (ESBLs), or these drugs plus cephamycins, i.e., plasmidic or hyperpro-duction of chromosomal cephamycinases have recently emerged as important nosocomial pathogens (1,2). Some of these strains cannot be reliably detected by clinical microbiology laboratories by using conventional susceptibility tests (3), and even when recognized, treating infections caused by these strains can be challenging because therapeutic options are limited. Infections attributable to such strains are associated with prolonged hospital stays, increased healthcare costs, and an increased number of deaths if appropriate therapy is delayed (4,5). To date, almost all reports of infection or colonization with ESBL-and plasmidic cephamycinase-producing E. coli (i.e., extended-spectrum cephalosporin-resistant E. coli [ESCREC]) have involved hospitalized patients or nursing home residents (3,6). The few reported patients with community-acquired infection have been elderly and debilitated and have had hospital contact, important coex-isting conditions, or both (3,6). E. coli, including resistant strains, may be transmitted within the community through the food supply. Indeed, other gram-negative enteric pathogens, notably Salmonella enterica, are a frequent cause of foodborne disease and, increasingly, are associated with antibiotic resistance, including antibiotic resistance to ESCs (7–11). Available data regarding other resistant E. coli suggest that ESCREC could also be disseminated through the food supply (12–19). The cefoperazone-containing medium routinely used in our laboratory for the isolation of Campylobacter occasionally yields other bacteria with hyperproduction of chromosomal β-lactamases or their plasmidic derivatives, as well as strains carrying extended-spectrum β-lactamases (unpub. data). By using this media, …