Emergence of Multidrug‐ResistantSalmonella entericaSerotype Newport Infections Resistant to Expanded‐Spectrum Cephalosporins in the United States

Abstract

We describe a field investigation in New England that identified the emergence and epidemiology of new strains of multidrug-resistant Salmonella, Newport-MDRAmpC, and summarize the Center for Disease Control and Prevention's surveillance data for these infections. In Massachusetts, the prevalence of Newport-MDRAmpC among Salmonella serotype Newport isolates obtained from humans increased from 0% (0/14) in 1998 to 53% (32/60) in 2001 (P<.001). In a retrospective case-control study, infection with Newport-MDRAmpC was domestically acquired and was associated with exposure to a dairy farm. Isolates from both humans and cattle had indistinguishable or closely related antibiograms and pulsed-field gel electrophoresis patterns. Nationally, the prevalence of ceftriaxone-resistant Salmonella increased from 0.5% in 1998 to 2.4% in 2001; 85% of the isolates in 2001 were Newport-MDRAmpC, and at least 27 states have isolated these strains from humans, cattle, or ground beef. These data document the widespread emergence of Newport-MDRAmpC strains in the United States and show that the 5-fold increase in the prevalence of Salmonella resistant to expanded-spectrum cephalosporins, between 1998 and 2001, is primarily due to the emergence of Newport-MDRAmpC strains.

Ceftriaxone-ResistantSalmonella entericaSerotype Newport, France

“…It has been hypothesized that use of ceftiofur, a third-generation cephalosporin licensed in the United States for use in cattle, could have selected for Newport MDR-AmpC (2-4,7). Several observations and case-control studies suggested beef and milk from dairy cattle were substantial sources of Newport MDR-AmpC infection in humans (6)(7)(8).…”

Extended-Spectrum-β-Lactamase (TEM-52)-Producing Strains of Salmonella enterica of Various Serotypes Isolated in France

“…The last report concerned TEM-52-producing isolates of serotype Enteritidis from a hospital outbreak One hypothesis for the emergence of TEM-52-producing Salmonella is the nosocomial acquisition by the exchange of ESBL genes among enteric bacteria frequently encountered in hospitals and selected by traces of ESC used in humans. An alternative hypothesis that has been suggested in a report of ESBL (SHV-12)-producing Salmonella, and with the emergence of Newport MDRAmpC, is the transmission through the food chain and consequently to antibiotic selection pressure in livestock (6,9). In our study, the isolates were generally not acquired from a hospital, and we suspected the second hypothesis but we didn't have evidence for it.…”

Acute diarrhea associated with Salmonella enterica in Belo Horizonte-MG: prevalence and characterization of isolates

“…Notwithstanding, prescription of antimicrobial drugs is necessary in some specific situations (15,25,26,28,30,33) . As observed in several other infections, the high frequency of multidrug resistance Salmonella strains has made the selection of antibiotics a medical challenge (8,16,23,34,38) . Chloramphenicol, ampicillin, and trimethoprim-sulfametoxazole could be employed for treating patients with salmonellosis.…”