Laboratory investigation and comparison of Salmonella Brandenburg cases in New Zealand

Abstract

An apparent increase in the incidence of S. Brandenburg in New Zealand, coupled with the possibility that the virulence of the organism may also be changing, prompted this study. Three typing methods: macro-restriction fragment length polymorphism (MRFLP) profiling using pulsed field gel electrophoresis (PFGE), plasmid profiling and antimicrobial susceptibility profiling were used to determine strain diversity amongst 115 recent and historical isolates of S. Brandenburg from both human cases and non-human sources. Antimicrobial resistance was noted only in three isolates. Plasmids of varying sizes were found in 31 isolates. MRFLP analysis resulted in 13 different patterns. Combining the three sets of typing data yielded 24 composite types. Comparison of composite type, isolation date and geographical location of case allowed the retrospective recognition of seven potential clusters during the 5-year study period. Composite types of 24 (80%) of the non-human isolates tested were indistinguishable from human isolates, suggesting that human infection may be via a number of vehicles. Although not cost-effective for routine use on all salmonella isolates, the methods used in this study are an important adjunct to serotyping for discrimination within an emerging serotype.

Salmonella Brandenburg - emergence of a new strain affecting stock and humans in the South Island of New Zealand

“…In addition, isolates from 17 blackbacked gulls, two dogs, two cattle and 45 human cases in the South Island were also indistinguishable from the sheep isolates. This is evidence of a clonal strain, which differed signifi cantly from the 13 different profi les typed from human isolates recovered between 1 January 1990 and 31 March 1995 (Wright et al 1998).…”

“…A representative random selection of isolates from routine cases submitted to veterinary diagnostic laboratories, the black-backed gull and sheep-yard dust studies, and from human cases were typed after PFGE, using a method adopted from Wright et al (1998).…”

“…obs.). In 1995, 13 different strains, based on molecular patterns identifi ed using pulsed-fi eld gel electrophoresis (PFGE), were identifi ed from 115 recent and historical isolates from both human and non-human cases (Wright et al 1998).…”

A Pilot with Pain in His Leg: Thigh Abscess Caused by Salmonella enterica Serotype Brandenburg

“…Although most cases of serotype Brandenburg are sporadic, the species has also been described in national epidemics (1,14). An extensive study in New Zealand including pulsed-field gel electrophoresis and macrorestriction fragment length polymorphism revealed that, among 115 isolates, seven clusters were defined during a 5-year time period (14).…”