New resistance gene found in Salmonella isolated from chickens
Published: June 2, 2017
Source : http://www.cidrap.umn.edu/
A team of Canadian scientists has identified a gene that confers resistance to the broad-spectrum antibiotic fosfomycin, according to a study yesterday in Antimicrobial Agents and Chemotherapy.
The gene, dubbed fosA7, was found in 15 Salmonella enterica isolates from broiler chickens in British Columbia. The isolates were of the Salmonella Heidelberg serotype, which is commonly identified in poultry and has become one of the leading causes of salmonellosis in humans. In recent years, Heidelberg strains have become more resistant to antibiotics, limiting therapeutic options. The gene was also found in three other Salmonella serotypes—Agona, Montevideo, and Tennessee.
Although polymerase chain reaction (PCR) testing showed that the gene was exclusively located on the chromosome of the Salmonella Heidelberg isolates, the concern is that fosA7 could potentially be spread to other strains of Salmonella and other families of bacteria if transferred to plasmids—small, floating pieces of DNA that can be shared among bacteria through a process known as horizontal gene transfer.
"If it's on the chromosome, and it jumps to the plasmid, and the plasmid gets into another [type of bacteria], then the situation becomes worse," corresponding author Moussa Diarra, PhD, a research scientist with Agriculture and Agri-Food Canada, told CIDRAP News.
Increased use of fosfomycin in human and veterinary medicine would then increase the prevalence of the gene.
High levels of resistance
To see whether fosA7 could be transferrable, the scientists made a clone of the gene and copied it onto a plasmid inserted into a sample of the Salmonella serotype Enteritidis. Antibiotic susceptibility tests on the modified Enteritidis strains showed that a more than 256-fold increase in the minimum inhibitory concentration (MIC) of fosfomycin was needed to prevent growth of the bacteria.
"These results further suggest the fosA7 is responsible for fosfomycin resistance and if transferred on plasmids, it can induce a high level of resistance in the recipient bacterial strain," the authors write.
Fosfomycin is an older, well-tolerated antibiotic with activity against both gram-positive and gram-negative bacteria. It has been used to treat a variety of human infections, including urinary tract infections, and is considered a safe alternative for treating infections caused by multidrug-resistant bacteria, including those caused by Salmonella. The existence of a gene that could lead to the failure of fosfomycin would be highly problematic.
"It's an important antibiotic," Diarra said. "If we have resistance to it, too, then [treatment] becomes complicated."
As a result, Diarra and his colleagues call for "vigilant monitoring" for the spread of fosfomycin resistance in bacteria isolated from humans and animals.
Nontyphoidal Salmonella causes an estimated 1.2 million foodborne illnesses and about 450 deaths each year in the United States, according to the Centers for Disease Control and Prevention. The agency's most recent estimate of antibiotic-resistant Salmonella infections put the burden at 6,200 cases annually.
Published by Chris Dall | News Reporter | CIDRAP News | May 23, 2017.
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Soavet
14 de junio de 2017
Ali, this simply means that if that new salmonella Fosfomycin resistant gene fos A7 is transfered to a human through consumption of such infected chicken, that infection maybe resistant to the antibiotic Fosfomycin, and that is the whole extent of food safety, public health and all that is what one health, one medicine is all about.
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Soavet
5 de junio de 2017
This is an interesting findings on one of the etiology of resistance development to prevailing antibiotic on salmonella enterica in poultry,which further proved the risk of cross resistances through the plasmid transfer of the fosA7 Factor responsible for this resistance development
I wish to complement from various research findings on mycotoxin of a possibility of their molecular interactions with hormones and microorganism to reverse functions and create resistances
Some mycotoxin like Zearalonone could modify the molecular structure of the hormone estrogen, thereby causing reproductive disruption in pig ,Broiler Breeder and Layer Breeder stocks
It was reported earlier by scientists that Zearalinone because of its similar molecular structure, with the female hormone estrogen do compete with the cytoplasmic oestrogen receptor to produce alpha Zearalenone and Beta zearalenone( likened to a mutation efect)responsible for hyper oestrogen responses in Breeder and in sows(Olmix publications)
Similarly the theory that mycotoxin could trigger an increase in CYTOKINS production that could result in the production of non specific antibodies could also potentiate resistances to antibiotic efficacy in therapy
I wish to import the experiences of Dr Bohama from NEPAL on a forum discussion of mycotoxin, reported in engormix discussion on Mareks vaccination failures, that this metabolite was responsible for vacination failures to Mareks in NEPAL, similar to report published in engormix on Nigeria case studies by Dr Stephen Adejoro
In a Panel discussion on mycotoxin initiated by Dr Wosniakowski from Lublium Poland ,on repeated Mareks disease vaccination failure,he concluded in the summary of the panelist discussion that 'The main problem in achieving a successful vaccination is the hygine and early infection to mareks as was pointed out by Dr Adejoro" (engormix panelist discussion on Mareks Vaccination failure www.engormix.com )
While I commend this study by the team of Canadian experts,I wish to plead for a follow up research by other international animal food security experts on the possible genetic implications of mycotoxins on resistances develpment to antibiotics
Livestock Industry Foundation For Africa NGO www.lifango.org is dedicated to encourage related studies to boost animal food security world wide
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13 de junio de 2017
Please can you explain about impact on human due to new resistance gene of Salmonella isolated from chicken?
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