• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

Animal & Veterinary

  • Print
  • Share
  • E-mail

Surveillance in Humans by Ezra Barzilay, M.D., CDC

DR. BARZILAY: Good morning. It’s a pleasure to be here today. My name is Ezra Barzilay and over the next few minutes I will talk to you about the human ARM off the National Antimicrobial Monitoring System or NARMS.

(Slide)

NARMS monitors the susceptibility of antimicrobial agents among enteric bacteria from humans, food and animals by collecting surveillance information of the following areas. Core surveillance, retail foods survey, outbreak isolates surveillance, and commensal organisms. In addition we conduct a series of activities that are dedicated in promoting the appropriate antibiotic use in veterinary medicine and animal agriculture.
I will talk a little bit about each of those components now in a little bit more detail.

(Slide)

Our core surveillance provides a centralized source of antimicrobial resistance data from major surveillance systems, including human, animal and retail food data using methods as you have already heard.

The retail food surveillance monitors the treads and changes in the prevalence of resistance among enteric bacteria isolated from four retail food commodities, which are listed here.

(Slide)

The outbreak isolates surveillance characterize the antimicrobial resistance attributes of bacterial pathogens isolated from foodborne disease outbreaks. And finally commensal organisms surveillance provides ongoing monitoring for resistance among Enterococci and E. coli, commensal bacteria that are traditionally thought to cause disease in hospital settings.

(Slide)

In 1994 NARMS developed an educational ARM closely modeled after “Get Smart” in known antibiotics work, it was called “Get Smart: Know when Antibiotics Work on the Farm.” And it was meant to promote the appropriate antibiotic use in veterinary medicine and animal agriculture.
We have since established a public health partnerships with veterinarians and with veterinary educators in nine states to develop educational materials to promote the appropriate use of antimicrobial in agriculture and veterinary setting and to foster collaboration between public health agency, academic institutions and animal health industries.

These efforts are centered around a development of a web based education program for vet students that combines aspects of microbiology, pharmacology, infectious diseases and public health to promote the appropriate use of antibiotics. This program is piloted by the Michigan State School of Veterinary Medicine and is actually being launched this fall with the first class of veterinary students.

(Slide)

As you have probably seen now in a couple of presentations and I suspect you will see several more, these are the pathogens that we test for in NARMS.

(Slide)

Our human clinical isolates are identified by state health departments and then submitted to NARMS laboratory for antimicrobial resistance testing. It’s the human arm of NARMS we receive every 20th non-typhi Salmonella, Shigella and E. coli 0157. We receive all S. typhi, Paratyphi A and C, Listeria and non-cholera Vibrio, as well as a representative sample of Campylobacter from ten FoodNet sites.

(Slide)

Our objectives are to monitor trends in antimicrobial resistance among foodborne bacteria from humans, retail meats and animals. To disseminate timely information on the resistance to promote interventions that reduce resistance among foodborne bacteria. To conduct research to better understand the emergence, persistence and spread of antimicrobial resistance. To provide data for decision-making related to the approval of safe and effective antimicrobial drugs for animals. And to promote the prudent use of antimicrobials in veterinary settings.

(Slide)

To give you a better sense of our work I would like now to share with you a few of our findings.

In 2009 NARMS examined the patterns of resistance to clinically important antimicrobials among non-typhoidal Salmonella, finding that three percent of all non-typhoidal Salmonella were resistant to ceftriaxone, two percent to nalidixic acid, 59 percent of S. typhi were resistant to nalidixic acid, 23 percent of Campylobacter resistant to ciprofloxacin and 3 percent resistant to erythromycin.

(Slide)

In addition we have examined the burden of and trends in multidrug-resistant Salmonella under surveillance. Finding that 28 percent of all S. typhimurium were resistant to three or more classes of antimicrobials, 14 percent of Salmonella Newport were resistant to three or more classes.

We examined the azithromycin MIC distribution of Shigella sone from isolates collected from outbreaks as well as our surveillance. The antimicrobial resistance patterns among representative bacterial isolates from foodborne disease outbreaks dating back to 2005.

(Slide)

We identified amino glycoside resistance determinants, and give specific examples, our lab identified armA and rmtC among non-typhoidal Salmonella isolates. Examined Plasmid-mediated quinolone resistance mechanisms among non-typhoidal Salmonella isolates. Identified and characterized the CTX-M-producing Shigella isolates.

(Slide)

Now, I would actually like to share with you some data from this year’s report, which is about to be published in the next few days or a couple of weeks at the most on the web.

This is a graph of the percent of non-typhoidal Salmonella resistant to ceftiofur and showing also decreases of ceftriaxone by year from 1996 to 2008. There are several things that I would like to point out on these graphs. The first thing -- let me see if I have a pointer, there you go.

So, in yellow right there you will see the percent resistance to ceftiofur and in green a measure of decreased susceptibility to ceftriaxone.
Now in non-typhoidal Salmonella, susceptibility resistant increased from .2 percent in 1996 to 2.9 percent in 2008. As you can see there’s a very similar trend in the decreased susceptibility to ceftriaxone. And as you can probably gauge from this graph, susceptibility resistant is very closely associated with decreases of --- ceftriaxone.

And I should mention at this point that a few weeks ago the CSLI released new break points for ceftriaxone which are reflected in this graph hence making the two measurements very close.

Additionally our lab has been exploring various molecular mechanisms for the drive resistance phenotypes, and in general resistance to ceftriaxone is largely governed by plasma called CMY, in fact we rarely find any other mechanism that for this type of resistance. With that being said our surveillance identified the first domestically acquired --- infection with a different mechanism, specifically CTXM5, which was recently published by our lab scientist in EID last year.

(Slide)

This is a graph showing the percentage of --- S. Typhimurium showing --- resistance phenotype, also knows as ACSSuT, in fact resistance to ampicillin, chloramphenicol, streptomycin, tetracycline by year from 1996 to 2008. I have included here before 1996, the years from 1998 to -- I’m sorry, 1980 to 1995, which were a series of pilot studies done before the inception of NARMS. And then starting with the establishment of NARMS and the systematic surveillance beginning in 1996.

(Slide)

This is a graph showing Salmonella Newport with the same resistance phenotype, for the same years. And again including the years prior to the NARMS being established. Now, these pilot studies were not done nationwide, these were specific counties.

(Slide)

This is a graph showing Salmonella Newport with the resistance phenotype known as MDR-AmpC. And MDR-AmpC is a resistance to -- multi-drug resistance pattern that includes --- resistance as well as decreases ability to susceptibility to ceftriaxone and the resistance to amoxicillin-clavulanic acid combination.

In Salmonella Newport MDR-AmpC was first detected in 1998 and that was in about one percent of isolates. It increased to 18 percent in 1999 and peaked at 25 percent in 2001. And although overall MDR-AmpC has started to decline, Salmonella Newport, after 2001, it persisted and is still detected in 11 percent of isolates in 2008.

(Slide)

This is a slide showing the percent of non-typhoidal Salmonella resistance to nalidixic acids. And showing the increases to ciprofloxacin by year.

(Slide)

Specifically in Salmonella and S. enterididis on nalidixic acid resistance increased from .9 in 1996 to 6.9 in 2008. S. enterididis accounts for 34 percent of all known nalidixic acid resistance among non-typhoidal Salmonella.

(Slide)

And now let’s take a look at Campylobacter. Point of much discussion over the last few years. Campylobacter is the leading cause bacterial gastroenteritis in the United States. Poultry is a major source of human infection. And fluoroquinolones are among the most frequently prescribed antimicrobial agents for the treatment of Campylobacterosis.

This slide shows the percent resistance to fluoroquinolones on some Campylobacter, isolated from humans over the last ten years. I would like to note a few things. First the approval of ciprofloxacin for human use in 1996.

A pilot study predating NARMS in 1989 showing no resistance. The approval for fluoroquinolones use in poultry in 1995. And as we know the withdrawal of approval ---floxacin use in 2005. The data for 2008 shows that the vast -- the peak for --- is 25.8 percent in 2007, remains fairly stable at 22.5 percent in 2008.

(Slide)

Finally, I would like to show a slide that is a little bit, maybe a little bit difficult to read, but this is the proportional graph showing the percent of non-typhoidal Salmonella, showing the --- resistance phenotype, but showing what proportion of it is due to --- typhimurium in green, Newport and in yellow, and the combined all other serotypes in the white on the top.

We are seeing an overall trend in decreased prevalence of typhimurium in the last ten years. And for reasons that we can’t entirely account for. But what we’re seeing is that the decrease in prevalence of typhimurium since it carries the majority of the resistance phenotype is also driving the realative decrease in the presence of the --- phenotype, ACSSuT.

(Slide)

All of this data can be found in our reports, both the Executive Summary Report that Beth Karp mentioned a few minutes ago, as well as the Human Isolates Report for 2007, which is already published. The 2008 annual report is due to be published on the web in the next few weeks.
Thank you very much for your attention.

(Applause)

DR. GREEN: Our next speaker will be Doctor Paula Fedorka-Cray, who I’m sure most of you know. Doctor Cray is currently the Research Leader of the USDA ARS, Bacterial Epidemiology and Antimicrobial Research Unit in Athens, Georgia. And her research focuses on the ecology and pathogenesis of antimicrobial resistance. She’s also the Director of the Animal ARM of the National Antimicrobial Resistance Monitoring System and Co-Director of USDA VET NAV.