A PERFECT STORM OF ANTIBIOTIC RESISTANCE
Section 13
Antibiotic Resistance in Animals and Birds 9/09/2011
Back to Myth # 4
In 1982, M. Hinton, et al., investigated “The persistence of drug resistant Escherichia coli in the intestinal flora of healthy
broiler chicks.” They said, “Antibacterial drugs (oxytetracycline, streptomycin and sulphonamides) were included in the
drinking water of healthy broiler chicks from the sixth to the twentieth day of life to select a resistant gut flora. On the
twenty-first day the birds were divided into three groups and reared in separate rooms until 100 days of age. One group
was housed in cages with wire floors while the others were reared on litter. Faeces from adult hens were added regularly
to the litter of one of these groups to determine its effect on the gut flora of the chicks. The ecology of Escherichia coli
was studied using O-serotyping, biotyping and antibacterial drug resistogram typing. The proportion of E. coli in the
dominant faecal flora resistant to two to four antibacterial drugs increased with time to reach a peak several days after
the drugs were withdrawn. Thereafter, the level of drug resistance in the E. coli declined equally in all three groups. The
majority of organisms with multiple resistance were derived from biotypes of O-serotypes initially resistant to only one
drug and were identified before the drugs were administered. The decline in the level of resistance in the dominant
faecal flora after the fourth week was due to the appearance of either new O-serotypes or new biotypes of O-serotypes
previously shown to be multiply resistant, and which were either sensitive or resistant to only one drug. It is probably that
these new strains were derived from the food since several O-serotypes appeared simultaneously in all three groups of
birds.”
http://www.ncbi.nlm.nih.gov/pubmed/6752273
In 2000, Patrick L. McDonough, et al., Diagnostic Laboratory, Department of Population Medicine and Diagnostic
Science, College of Veterinary Medicine, Cornell University at Ithaca, reported on the “Diagnostic and Public Health
Dilemma of Lactose-Fermenting Salmonella enterica Serotype Typhimurium in Cattle in the Northeastern United States.”
They said, “To differentiate Salmonella from other Enterobacteriaceae, bacteriologists use lactose fermentation as a key
biochemical test. As early as 1887, it was known that Escherichia coli was a lactose fermenter and that Salmonella was
not a lactose fermenter. Therefore, most differential plating media commonly developed and used today for the isolation
of Salmonella contain lactose. – The presence of lactose-fermenting Salmonella strains in clinical case materials
presented to microbiology laboratories presents problems in detection and identification. Failure to detect these strains
also presents a public health problem. The laboratory methods used in detecting lactose-fermenting Salmonella enterica
serotype Typhimurium from six outbreaks of salmonellosis in veal calves are described. Each outbreak was caused by a
multiply-resistant and lactose-fermenting strain of S. enterica serotype Typhimurium. The use of Levine eosin-methylene
blue agar in combination with screening of suspect colonies for C8 esterase enzyme and inoculation of colonies into
sulfide-indole-motility medium for hydrogen sulfide production was particularly effective for their detection. A hypothesis
for the creation of lactose-fermenting salmonellae in the environment is presented. It is proposed that the environment
and husbandry practices of veal-raising barns provide a unique niche in which lactose-fermenting salmonellae may
arise. – Since 1907, there have been various reports of the occurrence of lactose-fermenting (Lac+) Salmonella in
humans, such as Lac+ Salmonella enterica serotype Virchow, S. enterica serotype Tennessee, S. enterica serotype
Indiana, S. enterica serotype Agona, S. enterica serotype Typhimurium, S. enterica serotype Oranienburg, S. enterica
serotype Tuebingen, S. enterica serotype Newport, S. enterica serotype Typhi, S. enterica serotype Java, and S.
enterica serotype Toulon. Lac+ S. enterica serotype Typhimurium and S. enterica serotype Anatum have been reported
from dried milk products and milk-drying equipment. There have been, however, only a few accounts of animal
isolations; e.g., from 1969 to 1971 in Arizona, Lac+ S. enterica serotype Typhimurium was isolated from avian, bovine,
canine, and porcine hosts, with most of the Lac+ isolates coming from calves that had both high morbidity and mortality
rates. ”
http://jcm.asm.org/cgi/content/full/38/3/1221
In a 2002-03 EPA Research Project, Katharine G. Field, Oregon State University, reported on "Novel Antibiotic-Resistant
Bacteria Formed in the Environment as a Result of Fecal Pollution." Field said, "This research project was proposed
after we measured the widespread occurrence of fecal Bacteroidales spp. in surface waters. Furthermore, we found that
tetQ, a gene for tetracycline resistance commonly carried by Bacteroidales bacteria in the genera Bacteroides and
Prevotella, is distributed widely in estuarine and river waters. We showed that laboratory strains of Bacteroides bacteria
are able to transfer antibiotic resistance from one strain to another in 15° seawater microcosms. This suggested that
these bacteria could provide an important source of antibiotic resistance, possibly leading to the development of novel
tetracycline resistant bacteria through an environmental route. -- Antibiotic resistant bacteria often are assumed to arise
under selective pressure from exposure to low levels of antibiotics. Our purpose was to investigate the extent to which
antibiotic resistance can spread independent of exposure to antibiotics. -- The following animal species contained fecal
tetQ sequences (frequency of occurrence of tetQ in individual samples in parentheses): elk (100%), red fox (100%),
coyote (100%), black tail deer (50%), opossum (100%), pheasant (100%), squirrel (100%), and raccoon (50%). Seal,
mallard, pigeon, bobcat, and skunk did not contain tetQ sequences in their feces -- High sequence identity among wild
animal fecal sequences and known tetQ gene sequences suggested that the genes were acquired recently in the gut
microbiota of the wild animals. Because fecal samples were collected from animals immediately after arrival at the
rehabilitation facility, the animals are likely to have acquired the antibiotic resistance genes in their local environment. --
Laboratory and mesocosm experiments suggest that Bacteroidales fecal bacteria survive in the environment for far
longer than one might expect of strictly anaerobic bacteria. BrdU uptake data demonstrate growth of Bacteroidales cells
during aerobic incubation of sewage influent, suggesting that Bacteroidales fecal bacteria may be able to persist and
grow in low oxygen refugia within streams, lakes, estuaries, and bays. -- Nonhuman host-animal feces can spread many
pathogens and also may serve as a source for emergent zoonotic disease. This research demonstrates that the spread
of antibiotic resistance genes by fecal bacteria from both humans and domestic animal sources must also be a human
and animal health concern."
http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/6310/report/F
In 2005, Morten Helms, Steen Ethelberg, Kåre Mølbak, and the DT104 [virus] Study Group, Statens Serum Institut at
Copenhagen, reported on a survey, “International Salmonella Typhimurium DT104 Infections, 1992–2001.” They found,
“S. Typhimurium [infected with virus] DT104 was first isolated in the early 1980s in the United Kingdom and later became
endemic in bovine animals, from where it spread to the whole food animal production in that country. Throughout the
1990s, it spread to other parts of the world, and it is now a common Salmonella type in many countries, including the
United States, the United Kingdom, Germany, and France. DT104 is common in a broad range of food animals, such as
poultry, pigs, and sheep. This phage type has become a matter of concern because of its rapid international
dissemination in the 1990s and its ability to readily acquire additional resistance traits to other, clinically important
antimicrobial drug classes, such as quinolones, trimethoprim, and cephalosporins. A global survey of salmonellosis and
Salmonella serotyping was published in 2002 (24). However, relatively little information has been compiled on the global
spread of DT104 and MDR S. Typhimurium. Therefore, we have conducted a survey to describe the pandemic of
DT104 and MDR S. Typhimurium. – other phage [virus] types, such as U302, DT120, DT12, and DT193, were reported
to play a smaller role in this development. – The survey implies that MDR S. Typhimurium poses a serious and
increasing public health problem in large parts of the world.”
http://www.cdc.gov/ncidod/Eid/vol11no06/pdfs/04-1017.pdf
In 2007, James R. Johnson, et al., Minneapolis Veterans Affairs Medical Center, reported on “Antimicrobial Drug–
Resistant Escherichia coli from Humans and Poultry Products, Minnesota and Wisconsin, 2002–2004.” They said,
“Selective processing of 942 human fecal and poultry samples yielded 931 unique E. coli isolates, which constituted the
study population. Of the 931 isolates, 530 (57%) were from human volunteers and 401 (43%) from poultry products. Of
the human isolates, 456 (86%) were from hospital patients and 74 (14%) from vegetarians. Of the poultry isolates, 289
(72%) were from conventionally raised retail poultry and 112 (28%) from poultry raised without antibiotics. The median
number of unique E. coli isolates per sample was 1 for human fecal samples and 2 for poultry (range 1–4 for both).
Overall, 331 isolates (70 human, 261 poultry) were classified as resistant on the basis of reduced susceptibility to TMP-
SMZ, quinolones/fluoroquinolones, and extended-spectrum cephalosporins. The remaining 600 isolates (460 human,
140 poultry) were susceptible to all these drug classes and were classified as susceptible (regardless of other possible
drug resistance). The resistant isolates were distributed by resistance phenotype as follows: TMP-SMZ, 154 (47 human,
107 poultry); quinolones, 115 (26 human, 89 poultry); and extended-spectrum cephalosporins, 114 (14 human, 100
poultry). The 7 fluoroquinolone-resistant isolates (5 human, 2 poultry) were analyzed within the quinolone-resistant
group.” http://www.cdc.gov/eid/content/13/6/838.htm
In 2007, Inge van Loo, et al., Elisabeth Hospital at Tilburg, reported on the “Emergence of Methicillin-Resistant
Staphylococcus aureus of Animal Origin in Humans.” They said, “In 2003 in the Netherlands, a new methicillin-resistant
Staphylococcus aureus (MRSA) strain emerged that could not be typed with Sma1 pulsed-field gel electrophoresis (NT-
MRSA). The association of NT-MRSA in humans with a reservoir in animals was investigated. The frequency of NT-
MRSA increased from 0% in 2002 to >21% after intensified surveillance was implemented in July 2006. Geographically,
NT-MRSA clustered with pig farming. A case–control study showed that carriers of NT-MRSA were more often pig or
cattle farmers (pig farmers odds ratio [OR] 12.2, 95% confidence interval [CI] 3.1–48.6; cattle farmers OR 19.7, 95% CI
2.3–169.5). Molecular typing showed that the NT-MRSA strains belonged to a new clonal complex, ST 398. This study
shows that MRSA from an animal reservoir has recently entered the human population and is now responsible for >20%
of all MRSA in the Netherlands. – On the basis of the above-mentioned findings, we conclude that this new MRSA strain
is of animal origin (pigs and probably cows). Transmission of MRSA between animals and humans has previously been
described, e.g., associated with colonized companion animals, horses, and persons who take care of them. However,
the MRSA clones in these reports were known human clones, suggesting human-to-animal transmission in origin.”
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2876750/
In 2007, Peter Collignon and Frank Aarestrup, reported on “Extended-Spectrum -Lactamases (ESBLs), Food, and
Caphalosporin Use in Food Animals.” They said, “The use of third- andfourth-generation cephalosporins in food animals
results in the development of bacteria carrying ESBLs. This involves not only food-associated pathogens, such as
Salmonella species, but also E. coli. These drug-resistant bacteria then spread to people via food and other routes (e.
g., groundwater water).This is occurring around the world.”
http://thewatchers.us/Antibioticresistants/CollignonAarestrupESBLsfoodCID2007.pdf
In 2008, F. Gionechetti, et al., University of Trieste, reported on “Characterization of Antimicrobial Resistance and Class
1 Integrons in Enterobacteriaceae Isolated from Mediterranean Herring Gulls (Larus cachinnans).” They said,
“Mediterranean herring gulls (Larus cachinnans) were investigated as a possible reservoir of antibiotic resistant bacteria
and of cassette-borne resistance genes located in class 1 integrons. Two hundred and fourteen isolates of the family
Enterobacteriaceae were collected from cloacal swabs of 92 chicks captured in a natural reserve in the North East of
Italy. They showed high percentages of resistance to ampicillin and streptomycin. High percentages of resistance to
trimethoprim/sulfamethoxazole were found in Proteus and Citrobacter and to chloramphenicol in Proteus. Twenty-two
(10%) isolates carried the intI1 gene. Molecular characterization of the integron variable regions showed a great
diversity, with the presence of 11 different cassette arrays and of one integron without integrated cassettes. The dfrA1–
aadA1a and aadB–aadA2 cassette arrays were the most frequently detected. Also the estX cassette, alone or in
combination with other cassettes, was detected in many isolates. From this study it is concluded that the enteric flora of
Mediterranean herring gulls may act as a reservoir of resistant bacteria and of resistance genes. Due to their feeding
habits and their ability to fly over long distances, these free-living birds may facilitate the circulation of resistant strains
between waste-handling facilities, crops, waters, and urban areas.” http://www.liebertonline.com/doi/abs/10.1089/mdr.
2008.0803?cookieSet=1&journalCode=mdr
In the 2011 study, “Frequency of Antibiotic Resistance in a Swine Facility 2.5 Years After a Ban on Antibiotics,” Sepideh
Pakpour, et al., said, “The addition of antibiotics to livestock feed has contributed to the selection of antibiotic-resistant
bacteria in concentrated animal feeding operations and agricultural ecosystems. The objective of this study was to
assess the occurrence of resistance to chlortetracycline and tylosin among bacterial populations at the Swine Complex
of McGill University (Province of Quebec, Canada) in the absence of antibiotic administration to pigs for 2.5 years prior
to the beginning of this study. Feces from ten pigs born from the same sow and provided feed without antibiotic were
sampled during suckling (n = 6 for enumerations, n = 10 for PCR), weanling (n = 10 both for PCR and enumerations),
growing (n = 10 both for PCR and enumerations), and finishing (n = 10 both for PCR and enumerations). The
percentage of chlortetracycline-resistant anaerobic bacterial populations (TetR) was higher than that of tylosin-resistant
anaerobic bacterial populations (TylR) at weanling, growing, and finishing. Prior to the transportation of animals to the
slaughterhouse, resistant populations varied between 6.5 and 9.4 Log colony-forming units g humid feces−1. In all pigs,
tet(L), tet(O), and erm(B) were detected at suckling and weanling, whereas only tet(O) was detected at growing and
finishing. The abundance of tet(O) was similar between males and females at weanling and growing and reached 5.1 ×
105 and 5.6 × 105 copies of tet(O)/ng of total DNA in males and females, respectively, at finishing. Results showed high
abundances and proportions of TetR and TylR anaerobic bacterial populations, as well as the occurrence of tet and erm
resistance genes within these populations despite the absence of antibiotic administration to pigs at this swine
production facility since January 2007, i.e., 2.5 years prior to the beginning of this study. This work showed that the
occurrence of bacterial resistance to chlortetracycline and tylosin is high at the Swine Complex of McGill University.”
http://www.springerlink.com/content/8331363732454563/
The experts would have us believe that animals and birds are the source of antibiotic resistant organisms on agricultural
land rather than picking up the antibiotic resistant organisms from land contaminated with reclaimed sewage effluent and
sludge. Studies promoting reclaimed water and sludge seldom mention antibiotic resistance. They will seldom mention
the gram negative Enterobacteriacea family of pathogens. Instead they use the name of the tests for the primary
Enterobacteriacea family, E. coli at 95°F (coliform) and E. coli at 112.1°F (fecal coliform) or E. coli 0157:H7. And
heaven forbid, that the experts would mention Yersinia pestis the source of the Black Plague in agricultural products.
Next Antibiotic Resistance in Agricultural Products
Back to Myth # 4