S. enterica is the most common form of Salmonella responsible for food poisoning and infects both humans and animals.
The paper’s authors focus on s. enterica subspecies Kentucky, claiming it is showing greater resistance to treatment with the drug ciprofloxacin in Canada.
“Similar drug resistance patterns and genetic backgrounds of s. enterica serovar Kentucky have been observed in Europe and linked to travel to countries in Africa.
‘Multidrug resistance’
“That most isolates had multidrug resistance phenotypes is of particular concern. Further studies are required to determine risk factors for acquisition of these infections in Canada.”
However, they also state: “Resistance to ciprofloxacin in Salmonella spp. is a growing concern because it limits the ability to treat invasive disease.”
The research is based on observation of 76 s. enterica Kentucky isolates submitted to the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) from 2003-2009.
Ciprofloxacin resistance
A total of 23 of these (30%) showed ciprofloxacin resistance. Thirty-five (46%) of the isolates were susceptible to all antimicrobial drugs tested.
The total number of isolates associated with human infections under the programme during the time period scrutinised was rare.
But of those that were, s. enterica Kentucky had a significantly higher rate of ciprofloxacin resistance than all other non-typhoidal Salmonella isolates, comprising two thirds of all resistant strains tested, the study claims.
Proportion demonstrating resistance leapt
In addition, the proportion of s. enterica Kentucky isolates demonstrating resistance to ciprofloxacin leapt from 22% in 2003 to 57% in 2009.
“Analysis of s. enterica serovar Kentucky isolates obtained during 2003-2009 from animal and retail meat samples as part of CIPARS did not identify any ciprofloxacin-resistant isolates,” the scientists claim.
“This finding suggests that human infections in Canada were not acquired from domestically produced food.”
Travel history for 11 out of 23 case-patients in Canada was obtained, showing they had visited Morocco, Egypt, Libya and Africa.
Source: ‘Ciprofloxacin-resistant salmonella enterica serovar Kentucky in Canada’; Centers for Disease Control and Prevention; Volume 19, Number 6 – June 2013; Authors: Michael Mulvey; David Boyd; Rita Finley; Ken Fakharuddin; Stacie Langner; Vanessa Allen; Lei Ang; Sadjia Bekal; Sameh El Bailey; David Haldane; Linda Hoang; Greg Horsman; Marie Louis; Lourens Robberts; John Wylie