Birds Carry Resistant Bacteria

Scientists find vancomycin-resistant Enterococci in crow fecal samples from across the U.S.

By | November 11, 2013

FLICKR, CUATROK77Antibiotic resistance is an increasing problem around the world, but the various ways that bacteria gain resistance genes are still not well understood. Now, researchers from Tufts University in Massachusetts, Binghamton University in New York, the University of California, Davis, and the University of Veterinary and Pharmaceutical Sciences Brno in the Czech Republic have found vancomycin-resistant Enterococci (VRE) in fecal samples from American crows (Corvus brachyrhynchos), which live in close proximity to humans in urban areas. Their work was published online this summer (August 6) in Environmental Microbiology.

“We’ve documented human-derived drug resistance where it shouldn’t be—in wildlife and the environment,” study coauthor Julie Ellis of Tufts University told Environmental Health News. “But we know very little about how this may impact public health.”

Ellis and colleagues collected 590 samples crow feces from four different locations in the United States—in California, Kansas, New York, and Massachusetts. They found that Enterococci in 2.5 percent of the samples carried vanA, one of nine vancomycin-resistance genes. In addition to being resistant to vancomycin, bacterial strains that the research team isolated were also resistant to other antibiotics, including erythromycin, ampicillin, and ciprofloxacin. The authors suggested in their paper that VRE could be spread by refuse from medical centers, and that because crows feed on garbage in urban areas, “decontamination efforts of the hospital waste and sewage should be rigorous to prevent the spread of VRE to the environment outside hospitals.”

Finding VRE in crows is “an indicator of the wide-reaching scale of the problem,” Lance Price, who is a professor of environmental and occupational health at George Washington University and did not participate in the research, told Environmental Health News. “Microbes connect the planet,” he continued. “The danger is that we enter a post-antibiotic era in which even our last-line drugs won’t work and routine infections become life-threatening.”

(Hat tip: Popular Science)

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Avatar of: James V. Kohl

James V. Kohl

Posts: 405

November 12, 2013

Excerpt: "...the various ways that bacteria gain resistance genes are still not well understood."

My comment: One way that may not be understood is the thermodynamically regulated organism-level thermoregulation of antibiotic resistance.  It facilitates Evolution of Escherichia coli rifampicin resistance in an antibiotic-free environment during thermal stress.The evolution of resistance in an antibiotic-free environment was attributed to beneficial mutations.

No experimental evidence suggests that mutations are fixed in the organized genome of any species from microbes to man. All evidence suggests that antibiotic resistance, like other benefits manifested at the cellular and organismal levels,  involves the nutrient-dependent pheromone-controlled physiology of reproduction. Thus, attributing rifampicin resistance to mutations would be as likely a missattribution as any other antibiotic resistance attributed to mutation-driven evolution.

If the observed potential for the evolution of ecological specialization of the niche occupied by rifampicin resistant E. coli is nutrient-dependent and pheromone-controlled, ecological and social niche construction can be placed into the proper context and its antibiotic resistance understood. In the proper context, the epigenetic effects of nutrients and their metabolism to species-specific pheromones controls reproduction in species from microbes to man, which means that antibiotic resistance is both nutrient-dependent and pheromone-controlled in microbes. That understanding of cause and effect in the context of epistasis might benefit our understanding of antibiotic resistance in other organisms. See for example: The cost of antibiotic resistance depends on evolutionary history in Escherichia coli

Avatar of: Dr Edo

Dr Edo

Posts: 29

November 12, 2013

Here is part of a note to the State of California discussing this:

Wes, many thanks for your time. I am told by your offices that there is no training or testing sewer plant operators in the following. Here is the issue and one wonders why sewer plant operators receive no training in this area? Please indicate how this slips by and has done so for many years when the literature on the topic is rather robust, the number of antibiotics that still work are diminishing and the pathogens are becoming unstoppable. All the while the SWRCB seems not to have its staff develop a study outline for sewer plant operators on this topic. The following is a slightly reworked comment on an article in Science News.


Here is an overview of the problem:

In the late 1970s, the US/EPA conducted a major study on how sewer plants generated, not just passed through, antibiotic resistant bacteria. That study documented that sewer plants were the primary contributor of resistant organisms to the aquatic environment. The references in that study noted that publications dating back into the mid 1950s showed the same results, see: The EPA study also noted that UV disinfection actually strengthened the levels of resistance in some bacteria. Others more recently have shown that use of chlorine enhances the virulence of these resistant organisms (

The spread of antibiotic resistant organisms through sewage and its byproducts is a principal and well documented avenue allowing contamination of humans and hence the advance of antibiotic resistance. The problem is that while the pathogens gain in resistance to the point of being unstoppable, our supply of functional drugs is diminishing. This crisis is noted by both the WHO and the CDC, but seems to have been overlooked by the state agency that should be directly on top of the problem. The question, why?

In the Science Daily News of 12 November there is a story on crows carrying human antibiotic resistant organisms,(h ttp:// ). Geese and gulls have also been shown to carry human resistant organisms. Artificial wetlands created to dispose of excess watstewater in which water fowl stop over during migration and containing sewer effluents are thought to contribute to this situation. Thus resistant organisms can be spread very long distances through migrating birds that have become contaminated in these artificial wetlands.

How do crows obtain these resistant microbes? California has many crows. As an example, the City of Santa Barbara uses reclaimed (recycled) wastewater to irrigate several parks golf courses and school playing yards. In 2004, the Water Environment research Foundation (WERF) did a major study of sites across the US producing reclaimed (recycled) wastewater. The WERF study looked at pathogen carriage in the finished and “disinfected” reclaimed water, finding that the typical tests used to allow that water to be released were faulty (see: WERF report 00-PUM-2T as well as Santa Barbara was part of that study.

About this same time my group was running tests on this Santa Barbara recycled water for antibiotic resistant bacteria, finding bacteria resistant to 11 of the 12 challenge antibiotics in our Kirby Bauer. These tests were rerun because of the seriousness of these findings and the series we ran showed essentially consistent results---the reclaimed water contained antibiotic resistant bacteria, seriously resistant bacteria. However, using the state approves standard water quality tests failed to show any problem. Thus, there is a serious flaw in the system and this was clearly spelled out in both the WERF report and Harwood report as well as our results. Additionally, there is no training on this topic as a requirement for operating a sewer plant, notwithstanding the rather robust history of finding that sewer plants actually generate and then release these resistant pathogens. Pathogens that in nature might never get together for gene exchange are thrust into each other in a sewer plant.

In our tests in Santa Barbara, these lab tests were conducted at two points in the reclaimed (recycled) water system. First as that water initially left the plant (point of release--POR) and then again at the sprinkler head as it was actually delivered (point of use--POU). Using the state approved standard test, at the point of release at the plant, the numbers were low to non-detect. At the point of use (sprinkler head), the same water contained bacteria in amounts that were so high, they were off the charts. Something was going on within the pipes as the water moved along. At the POR, bacteria can be in a stunned state called viable but non culturable (VBNC) and thus do not react in the state's standard tests. WERF has studied this for biosolids and showed that 20 minutes after successfully passing the standard test, bacterial numbers rocked up several magnitudes as the bacteria resuscitated from the VBNC state.

In discussing recycled water moving down the pipes, these stunned bacteria can also resuscitate and thus show up once again in the standard test. This might explain the results we obtained. The other option is that biofilms of bacteria were developing inside these pipes and then shedding. The end result was the water going on parks and children's playing fields was vastly out of compliance and carrying mulit-antibiotic resistant bacteria. These bacteria and their genes can become incorporated in the soil microbiota and thus available to foraging crows. See also the following papers on this: The point of all this is that while we are running out of antibiotics, the pathogens are increasingly resistant and we, ignorantly, are helping to spread resistant organisms into the environment. Since we use this environment, our  children with their immature immune systems are unnecessarily exposed. Once incorporated into the human gut biota, these resistant bacteria and genes can set up residence, thus, establishing tiny time bombs within.

Once in the gut, these microbes may be able to communicate and exchange genetic information with the human gut biota and set up lending libraries. Sjolund  (2005) looked at similar issues and notes that this genetic information is passed to and then amplified by the gut biota. Sjolund et al. further indicated that resistance in the normal flora, which once incorporated can last for years, might contribute to increased resistance in higher-grade pathogens through inter-species transfer. These authors go on to note that since populations of the normal biota are large, this affords the chance for multiple and different resistant variants to develop. This thus enhances the risk for spread to populations of pathogens. Furthermore, there is crossed resistance which can complicate treatment. For example, vancomycin resistance may be maintained by using macrolides. See: Sjolund, et al. Emerging Infectious Diseases, 2005, Sept.;11(9),1389 et seq.

But, with the current standards and lack of training in the crews that run sewer plants, especially tests using a single indicator, one would never see the pathogens. Thus, there is a likelihood of false negatives when using current standards. Although through these deficient standards, the water may meet standards, one must ask—-is it really safe if the standards fail to adequately test a suite of pathogens and the operators have no training in this? There is a rather well documented history of illnesses from water that passed standards.

Dr Edo McGowan, Medical Geo-gydrology

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