[USCC] antibiotics and manure

[Allison L H Jack]

Hi all,

Actually I would argue that antibiotics persisting in soils is an acute 
concern. Regardless of where they come from, microorganisms develop 
resistance to antibiotics over longer term exposure. Many human pathogens 
and opportunistic human pathogens are soil dwelling microorganisms. There 
is a clear potential for creating antibiotic resistant human pathogens. I 
have a friend working on this issue for his dissertation in Upsalla, 
Sweden. The Union of Concerned Scientists is also focusing on this issue. 
http://www.ucsusa.org/food_and_environment/antibiotics_and_food/

-Allison

p.s. a brief lit search on ISI turns up some recent studies:

Arikan, O. A., L. J. Sikora, W. Mulbry, S. U. Khan and G. D. Foster (2007). 
"Cmposting rapidly reduces levels of extractable oxytetracycline in manure 
from therapeutically treated beef calves." Bioresource Technology 98(1): 
169-176.Oxytetracychne (OTC) is a broad-spectrum antibiotic used in 
livestock production. The widespread use and relative persistence of OTC 
may encourage development of antibiotic-resistant bacteria. The objective 
of this study was to determine whether composting would substantially 
reduce the concentration of OTC found in manure from medicated animals. The 
effect of OTC on composting was also investigated. Five beef calves were 
medicated for 5 days with 22 mg/kg/day of OTC. Approximately 23% of the OTC 
fed to the calves was recovered in the manure. Manure samples collected 
from calves prior to and after medication were mixed with straw and 
woodchips, and aliquots of the subsequent mixtures were treated in 
laboratory composters for 35 days. In addition, aliquots of the 
OTC-containing mixture were incubated at 25 degrees C or sterilized 
followed by incubation at 25 degrees C. The presence of OTC did not appear 
to affect composting processes. Within the first six days of composting, 
levels of extractable OTC in the compost mixture decreased from 115 +/- 8 
mu g/g dry weight to less than 6 +/- 1 mu g/g dry weight (a 95% reduction). 
In contrast, levels of extractable OTC in room temperature incubated and 
sterilized mixtures decreased only 12-25% after 37 and 35 days, 
respectively. Levels of total heterotrophic bacteria and OTC-resistant 
bacteria in the finished compost mixture were roughly 30-fold higher and 
10-fold lower, respectively, than levels in the mixture prior to 
composting. Although the basis of the OTC disappearance during composting 
is not known, the preponderence of OTC-sensitive bacteria and the decrease 
of OTC-resistant bacteria in the finished compost suggests that OTC 
residues have been rendered biologically inactive or unavailable. (c) 2005 
Elsevier Ltd. All rights reserved.
Guan, J., A. Wasty, C. Grenier and M. Chan (2007). "Influence of 
temperature on survival and conjugative transfer of multiple anti 
biotic-resistant Plasmids in chicken manure and compost microcosms." 
Poultry Science 86(4): 610-613.The aim of this study was to determine if 
mobile plasmids carrying antibiotic-resistant genes could survive and be 
transferred in chicken manure maintained under conditions similar to those 
found in commercial cage layer operations and during composting. 
Escherichia coli J5 harboring a self-transmissible plasmid (RP4) and E. 
coli C600 harboring a mobile plasmid (pIE723) were used as plasmid donors; 
E. coli CV601 was used as a plasmid recipient. At 23 degrees C both 
plasmids were transferred to E. coli CV601 in chicken manure and in compost 
microcosms that consisted of a mixture of chicken manure and peat. The 
transfer frequencies ranged from 8.1 x 10(-5) to 2.4 x 10(-3) per donor 
cell in manure and from 2.4 x 10(-5) to 5.5 x 10(-4) per donor cell in 
compost microcosms. After 45 d of incubation at 23 degrees C, RP4, but not 
pIE723, was recovered by an exogenous isolation method although their E. 
coli hosts were not cultured from the microcosms. However, when the 
temperatures of the compost microcosms were elevated to 50 degrees C or 
above, neither the plasmids nor their E. coli hosts could be detected. The 
results suggested that composting of chicken manure at high temperatures 
could help prevent the spread of antibiotic-resistant genes via plasmids in 
the environment.
Kahle, M. and C. Stamm (2007). "Sorption of the veterinary antimicrobial 
sulfathiazole to organic materials of different origin." Environmental 
Science & Technology 41(1): 132-138.Sulfonamides (SA), ionizable, polar 
antimicrobial compounds, may reach the environment in substantial amounts 
by the spreading of manure. The environmental behavior of SA is still 
difficult to predict. We investigated the influence of the main factors 
supposed to control SA sorption to organic materials: composition of 
sorbent, solute chemistry, and contact time. For that purpose, 
sulfathiazole (STA) sorption to compost, manure, and humic acid after 1 and 
14 d was studied under sterile conditions. The experiments demonstrated 
that sorption was most strongly affected by contact time and pH. 
Irrespective of sorbent and pH, sorption continued substantially after the 
fast initial sorption within 1 d. For all sorbents and both contact times, 
STA sorption exhibited a pronounced pH dependence. Species-specific K-oc 
values decreased in the order K-oc(cation) > K-oc(neutral) > K-oc(anion). 
Differences in sorbent composition influenced STA sorption weaker. For the 
neutral STA species, NMR chemical shift regions assignable to ketonic, 
carboxylic, and phenolic C as well as aromatic C-H and methoxyl/N-alkyl C 
seemed to control sorption. For the cations, sorption followed the cation 
exchange capacities of the sorbents. STA sorption to manure and humic acid 
increased with higher ionic strength (0.31 M compared to 0.06 M) at pH 7.5.
Sakai, Y., T. Tsukahara and K. Ushida (2006). "Possibility of 
vancomycin-resistant enterococci transmission from human to broilers, and 
possibility of using the vancomycin-resistant gram-positive cocci as a 
model in a screening study of vancomycin-resistant enterococci infection in 
the broiler chick." Animal Science Journal 77(5): 538-544.In this study, 
vancomycin-resistant enterococci (VRE) from humans and vancomycin-resistant 
gram-positive cocci (VRPC) from pigs were examined for their ability to 
transmit in the chick intestine (Experiment 1). A model study on the spread 
speed of VRPC was also estimated from chick to chick under semi-production 
conditions with different administration routes (not inoculated, oral 
administration to a chick, sprayed on the floor) (Experiment 2). 
Furthermore, the disappearance of VRPC from their litter with composting 
processes was examined (Experiment 3). Each of six chicks was inoculated 
with VRPC or VRE at 1 day old in Experiment 1. All the chicks had VRPC or 
VRE in their glandular stomach at 22 days of age. In Experiment 2, 6 floor 
pens covered with sawdust were prepared and 20 chicks were allotted to each 
pen. The chicks were inoculated with VRPC at 1 day of age. The VRPC were 
detected in each group in cloacal swabs at 2 days of age (detection rate; 
20-80%). And they were also detected in the not-inoculated group. The VRPC 
detection rate gradually decreased, and detection was rare (0-10%) in the 
packing chicks (50 days old). VRPC were detected in the litter of each pen 
in Experiment 2. A composting process was effectively used to eliminate 
VRPC by the 6th week (Experiment 3).
Yang, H., B. Dettman, J. Beam, C. Mix and X. P. Jiang (2006). "Occurrence 
of ceftriaxone-resistant commensal bacteria on a dairy farm and a poultry 
farm." Canadian Journal of Microbiology 52(10): 942-950.Approximately 40 
samples of animal feces, drinking water, feed, bedding, pine wood shavings, 
compost, and manure slurry were collected from two animal research farms 
(one dairy and one poultry) and analyzed for ceftriaxone-resistant 
bacteria. Our study revealed that the total percentage of aerobic bacteria 
with reduced susceptibility to ceftriaxone (minimal inhibitory 
concentration (MIC) >= 16 mu g/mL) ranged from 0.9% to 10.8% in dairy feces 
and from 0.05% to 3.93% in chicken feces. The percentages of 
ceftriaxone-resistant bacteria (MIC >= 64 mu g/mL) were in the range of 
0.01%-2.3% in dairy feces and 0.01%-0.79% in chicken feces. Environmental 
samples contained a wide range of ceftriaxone-resistant bacterial 
populations. Among those environmental samples, fresh pine wood shavings 
used as chicken bedding contained the highest percentages (41.5%) of 
ceftriaxone-resistant bacteria, as determined by a plating method. A total 
of 105 ceftriaxone-resistant (MIC >= 128 mu g/mL) bacterial isolates were 
isolated from the above samples and tested for resistance to nine 
antibiotics: ampicillin, ceftriaxone, streptomycin, kanamycin, gentamicin, 
chloramphenicol, tetracycline, ciprofloxacin, and nalidixic acid. The most 
prevalent resistance pattern (34.3%) among isolates included resistance to 
all nine antibiotics. Results from this study suggest that 
ceftriaxone-resistant bacteria exist in farm environments, and the 
ceftriaxone resistance was frequently associated with resistance to 
multiple antibiotics. Environmental sources such as pine wood shavings used 
as bedding can be a potential reservoir for transmitting the 
multidrug-resistant bacteria.
Yu, Z. T., F. C. Michel, G. Hansen, T. Wittum and M. Morrison (2005). 
"Development and application of real-time PCR assays for quantification of 
genes encoding tetracycline resistance." Applied and Environmental 
Microbiology 71(11): 6926-6933.We report here the development, validation, 
and use of three real-time PCR assays to quantify the abundance of the 
following three groups of tetracycline resistance genes: tet(A) and tet(C); 
tet(G); and tet genes encoding ribosomal protection proteins, including 
tet(M), tet(O), tetB(P), tet(Q), tet(S), tet(T), and tet(W). The assays 
were validated using known numbers of sample-derived tet gene templates 
added to microbiome DNA. These assays are both precise and accurate over at 
least 6 log tet gene copies. New tet gene variants were also identified 
from cloned tet amplicons as part of this study. The utility of these 
real-time PCR assays was demonstrated by quantifying the three tet gene 
groups present in bovine and swine manures, composts of swine manure, 
lagoons of hog house effluent, and samples from an Ekokan upflow biofilter 
system treating bog house effluent. The bovine manures were found to 
contain fewer copies of all three groups of tet genes than the swine 
manures. The composts of swine manures had substantially reduced tet gene 
abundance (up to 6 log), while lagoon storage or the upflow biofilter had 
little effect on tet gene abundance. These results suggest that the method 
of manure storage and treatment may have a substantial impact on the 
persistence and dissemination of tet genes in agricultural environments. 
These real-time PCR assays provide rapid, quantitative, 
cultivation-independent measurements of 10 major classes of tet genes, 
which should be useful for ecological studies of antibiotic resistance.




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Allison L H Jack
Graduate Student
Department of Plant Pathology
Cornell University
335 Plant Science
Ithaca, NY 14850
607.273.5762
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