Stewardship / Resistance Scan for Sep 12, 2018

MDR bacteria in farmed salmon
Resistant E coli in dogs
Essential-antibiotic price hike

Chilean study finds multidrug-resistant gut bacteria in farmed salmon

Chilean scientists have found that extensive use of the antibiotics oxytetracycline and florfenicol leads to the selection of multidrug-resistant (MDR) bacteria in the gut microbiota of farmed salmon, according to a study yesterday in PLoS One.

To demonstrate the impact of antibiotic use in Chile's salmon farms, where more than 5,500 tons of antibiotics have been used over the last 10 years to help prevent and treat infections caused by the bacterium Piscirickettsia salmonis, the scientists selected 15 healthy Atlantic salmon from four salmon farms, then isolated and tested bacteria from fecal matter and intestines. They were particularly interested in oxytetracycline and florfenicol, because those are the two most administered antibiotics in salmon farming, mainly delivered through medicated feed.

In total, 47 bacterial isolates resistant to florfenicol and 44 resistant to oxytetracycline were isolated from the fish, with 38.3% showing a high degree of resistance to florfenicol and 34.1% showing a high degree of resistance to oxytetracycline. In addition, 6 of the 91 isolates were resistant to six other antibiotics—chloramphenicol, tetracycline, erythromycin, ampicillin, ciprofloxacin, and kanamycin—and were characterized as "super-resistant." Molecular analysis of the isolates identified several genes that confer resistance to florfenicol and oxytetracycline, which corroborated the phenotypic resistance that was observed.

"The information collected in the present study clearly indicate that using large amounts of antibiotics to treat industrially farmed animals has the consequence of selecting for multiresistant bacteria in the intestinal microbiota, which then have undeniable advantages when liberated into the environment through the feces," the authors write, warning that the release of feces with antibiotic resistance genes into the marine environment could increase the risk of fish pathogens acquiring those resistance elements and becoming untreatable.
Sep 11 PLoS One study


UK study: Common antibiotics boost risk of drug-resistant E coli in dogs

The use of broad-spectrum antibiotics for the treatment of bacterial infections in dogs can create a reservoir of antibiotic-resistant Escherichia coli within the canine gastrointestinal tract, UK researchers reported yesterday in the Journal of Antimicrobial Chemotherapy.

In the study, the researchers examined fecal samples from 127 dogs before treatment, immediately after treatment, and 1 month and 3 months post-treatment with one of five antibiotics—cefalexin, amoxicillin/clavulanate, cefovecin, clindamycin, or a fluoroquinolone. All confirmed E coli isolates then underwent antibiotic susceptibility testing, and resistant isolates were further analyzed for phenotypic extended-spectrum beta-lactamase (ESBL) and AmpC production and for the presence of resistance genes. The impact of treatment group per point in time and other factors on the presence of resistance were investigated using multilevel modeling.

The results showed that treatment with beta-lactams or fluoroquinolones was significantly associated with the detection of third-generation cephalosporin-resistant, AmpC-producing, MDR and/or fluoroquinolone-resistant E coli immediately after treatment. But at 1 month post-treatment, only amoxicillin-clavulanate was significantly associated with the detection of third-generation cephalosporin-resistant E coli. There was no significant difference at 3 months post-treatment for any of the antibiotics used. The detection of ESBL-producing E coli was not associated with use of any of the antibiotics administered at any time during the study.

The authors say the findings are important because they suggest that treatment with commonly used antibiotics can affect the commensal fecal flora of dogs, causing a shift toward a more resistant population of E coli that could be shared within households and healthcare settings and may cause extra-intestinal infections.

They conclude, "This information can be used to design biosecurity guidelines that limit transfer of such bacteria to in-contact individuals or to the environment, including barrier nursing, appropriate disposal of dog waste, and strict hand hygiene."
Sep 12 J Antimicrob Chemother study


Pharma CEO defends 400% essential antibiotic price hike

Nirmal Mulye, chief executive officer of the small Missouri-based drug company Nostrum Laboratories, said he hiked the cost of bottle of nitrofurantoin, an essential antibiotic, from  $474.75 to $2,392 last month because there was a "moral requirement to sell the product at the highest price."

Mulye was quoted in the Financial Times. Nostrum Laboratories makes a liquid version of the antibiotic, which was first developed in 1953 and used to treat bladder infections. The drug is considered an essential antibiotic by the World Health Organization (WHO).

Mulye said the decision to raise the price was a direct response to a similar raise by Casper Pharma, which prices a bottle of their branded antibiotic at $2,800.

"The point here is the only other choice is the brand at the higher price. It is still a saving regardless of whether it is a big one or not," said Mulye in the Financial Times.

Food and Drug Administration Commissioner Scott Gottlieb, MD, said on Twitter that "there's no moral imperative to price gouge and take advantage of patients," in reference to the story.  He also noted that there is no shortage of nitrofurantoin.
Sep 11 Financial Times story
Scott Gottlieb Twitter account

Newsletter Sign-up

Get CIDRAP news and other free newsletters.

Sign up now»


Unrestricted financial support provided by

Bentson Foundation Unorthodox Philanthropy logo and text 'Leading Underwriter'3M logoGilead 
Grant support for ASP provided by


  Become an underwriter»