Rapid and widespread dissemination of multidrug-resistant blaCMY-2 Salmonella Typhimurium in Mexico.

Objectives: We describe the emergence and dissemination of multidrug-resistant (MDR) Salmonella Typhimurium in humans, retail meat and food animals from Yucatan, Mexico.

Methods: Salmonella Typhimurium isolates were collected through an active surveillance system and tested for susceptibility to 12 antimicrobial agents. Isolates that were non-susceptible to ceftriaxone were tested with 10 additional antimicrobials and assayed by PCR for the presence of CMY, CTX-M, SHV, TEM and OXA beta-lactamase genes.

Biogenesis and replication of small plasmid-like derivatives of the mitochondrial DNA in Neurospora crassa.

For reasons that are not obvious, sets of related, small, plasmid-like elements appear spontaneously and become amplified in the mitochondria of some cytochrome-deficient and/or UV-sensitive mutants of Neurospora crassa. These plasmid-like DNAs are multimeric series of circular molecules, each consisting of a finite number of identical tandem repeats of a relatively short mtDNA-derived nucleotide sequence (monomer). The plasmid-like elements that have been characterized in this study consist of monomers that vary in length from 125 to 296 base pairs, depending on the strain of origin.

Nontyphoidal Salmonella from human clinical cases, asymptomatic children, and raw retail meats in Yucatan, Mexico.

Background: We report the results of a 3-year Salmonella surveillance study of persons with diarrhea; asymptomatic children; and retail pork, poultry, and beef in Yucatan, Mexico.

Methods: Isolates were characterized according to serotype, antimicrobial susceptibility, and genetic relatedness with pulsed-field gel electrophoresis.

Results: Salmonella Typhimurium was the most common serotype found in ill humans (21.

Changes in antimicrobial susceptibility of native Enterococcus faecium in chickens fed virginiamycin.

The extent of transfer of antimicrobial resistance from agricultural environments to humans is controversial. To assess the potential hazard posed by streptogramin use in food animals, this study evaluated the effect of virginiamycin exposure on antimicrobial resistance in Enterococcus faecium recovered from treated broilers. Four consecutive broiler feeding trials were conducted using animals raised on common litter.