Salmonella infantis in Cattle Feedlot Runoff

Ten isolates of Salmonella infantis (serologically typed) were found in litter and runoff collected from two experimental feedlots near the Kansas State University campus. Pathogenic implications are discussed relative to recreation water sites. Agricultural runoff maybe a source of viable salmonellae.     

Characterization of the Dominant Aerobic Microorganism in Cattle Feedlot Waste

The dominant aerobic microorganism in cattle feedlot waste (FLW) is a corynebacterium. It is ubiquitous to FLW except on sites where antibiotics are a constant part of the animals' diet. The organism requires DL-aspartic acid as its nitrogen source for growth, and individual strains also require or are stimulated by L-tyrosine; acetate serves as the carbon source. Amylolytic activity is weak; protease, lipase, and cellulase activities are nil. Despite the abundance of the organism, it probably does not decompose the waste appreciably.     

用于分析微生物种类组成的微生物生态学研究方法

对环境中微生物群落进行分析对于理解该环境中各类微生物的功能具有重要意义,因此日益受到重视。用于环境中微生物群落分析的方法很多,将简要介绍基于PCR的研究方法,原位杂交技术,基因芯片技术,宏蛋白质组学技术等研究方法的原理、应用及其优缺点。     

Transmission of Salmonella typhimurium among Feedlot Cattle after Oral Inoculation

Fifteen six-eight month old steers and bulls weighing approximately 160 kg were inoculated orally with a virulent strain of Salmonella typhimurium. Three or four inoculated animals were confined in each of four pens, immediately after inoculation, with approximately 22 uninoculated cattle. The pen size in the experimental feedlot was 23 x 46 m. The 15 intentionally inoculated animals all became infected and excreted Salm. typhimurium in their faeces. Two of them died of salmonellosis and more than half the cattle penned with the inoculated animals became infected within 8 d after exposure. Twenty-four of the animals were still excreting salmonellas 71 d after initiation of the experiment.     

Increasing Prevalence of Campylobacter jejuni in Feedlot Cattle through the Feeding Period

The prevalence of Campylobacter jejuni in commercial feedlot cattle was monitored throughout the feeding period by repeated bacteriologic culture of feces. Fecal pats (n = 10) in 20 feedlot pens were sampled at 2-weeks interval beginning at entry into the feedlot and continuing until slaughter. The least-squares mean C. jejuni prevalence increased from 1.6% at the first sampling to 61.3% at the final sampling just prior to slaughter. Diverse C. jejuni pulsed-field gel electrophoresis macrorestriction profiles (MRP) were identified among the cattle isolates, but five prevalent MRP and minor variants accounted for >80% of all typed isolates. Chlorination of the water supplied to the water troughs of half of the pens did not affect C. jejuni prevalence in the cattle. Overall, the least-squares mean C. jejuni prevalences were 45.6 and 43.6% in chlorinated and nonchlorinated feedlot pens, respectively. The results of this study demonstrate apparent transmission of C. jejuni among feedlot cattle during the feeding period, unaffected by water chlorination, resulting in a high prevalence of C. jejuni excretion by cattle approaching slaughter.     

Microbial Flora of Pecan Meat

Microorganisms found associated with commercially shelled pecan meats are numerous and varied. No bacteria and only two fungal microorganisms, Aspergillus clavatus and Tricothecium species, were found on aseptically shelled pecans.     

Microbial Flora of Pecan Meat

Microorganisms found associated with commercially shelled pecan meats are numerous and varied. No bacteria and only two fungal microorganisms, Aspergillus clavatus and Tricothecium species, were found on aseptically shelled pecans.     

Effect of Proximity to a Cattle Feedlot on Escherichia coli O157:H7 Contamination of Leafy Greens and Evaluation of the Potential for Airborne Transmission

The impact of proximity to a beef cattle feedlot on Escherichia coli O157:H7 contamination of leafy greens was examined. In each of 2 years, leafy greens were planted in nine plots located 60, 120, and 180 m from a cattle feedlot (3 plots at each distance). Leafy greens (270) and feedlot manure samples (100) were collected six different times from June to September in each year. Both E. coli O157:H7 and total E. coli bacteria were recovered from leafy greens at all plot distances. E. coli O157:H7 was recovered from 3.5% of leafy green samples per plot at 60 m, which was higher (P < 0.05) than the 1.8% of positive samples per plot at 180 m, indicating a decrease in contamination as distance from the feedlot was increased. Although E. coli O157:H7 was not recovered from air samples at any distance, total E. coli was recovered from air samples at the feedlot edge and all plot distances, indicating that airborne transport of the pathogen can occur. Results suggest that risk for airborne transport of E. coli O157:H7 from cattle production is increased when cattle pen surfaces are very dry and when this situation is combined with cattle management or cattle behaviors that generate airborne dust. Current leafy green field distance guidelines of 120 m (400 feet) may not be adequate to limit the transmission of E. coli O157:H7 to produce crops planted near concentrated animal feeding operations. Additional research is needed to determine safe set-back distances between cattle feedlots and crop production that will reduce fresh produce contamination.     

Escherichia coli O104 in Feedlot Cattle Feces: Prevalence,Isolation and Characterization

Escherichia coli O104:H4, an hybrid pathotype of Shiga toxigenic and enteroaggregative E. coli, involved in a major foodborne outbreak in Germany in 2011, has not been detected in cattle feces. Serogroup O104 with H type other than H4 has been reported to cause human illnesses, but their prevalence and characteristics in cattle have not been reported. Our objectives were to determine the prevalence of E. coli O104 in feces of feedlot cattle, by culture and PCR detection methods, and characterize the isolated strains. Rectal fecal samples from a total of 757 cattle originating from 29 feedlots were collected at a Midwest commercial slaughter plant. Fecal samples, enriched in E. coli broth, were subjected to culture and PCR methods of detection. The culture method involved immunomagnetic separation with O104-specific beads and plating on a selective chromogenic medium, followed by serogroup confirmation of pooled colonies by PCR. If pooled colonies were positive for the wzx_O104 gene, then colonies were tested individually to identify wzx_O104-positive serogroup and associated genes of the hybrid strains. Extracted DNA from feces were also tested by a multiplex PCR to detect wzx_O104-positive serogroup and associated major genes of the O104 hybrid pathotype. Because wzx_O104 has been shown to be present in E. coli O8/O9/O9a, wzx_O104-positive isolates and extracted DNA from fecal samples were also tested by a PCR targeting wbdD_O8/O9/O9a, a gene specific for E. coli O8/O9/O9a serogroups. Model-adjusted prevalence estimates of E. coli O104 (positive for wzx_O104 and negative for wbdD_O8/O9/O9a) at the feedlot level were 5.7% and 21.2%, and at the sample level were 0.5% and 25.9% by culture and PCR, respectively. The McNemar’s test indicated that there was a significant difference (P < 0.01) between the proportions of samples that tested positive for wzx_O104 and samples that were positive for wzx_O104, but negative for wbdD_O8/O9/O9a by PCR and culture methods. A total of 143 isolates, positive for the wzx_O104, were obtained in pure culture from 146 positive fecal samples. Ninety-two of the 143 isolates (64.3%) also tested positive for the wbdD_O8/O9/O9a, indicating that only 51 (35.7%) isolates truly belonged to the O104 serogroup (positive for wzx_O104 and negative for wbdD_O8/O9/O9a). All 51 isolates tested negative for eae, and 16 tested positive for stx1 gene of the subtype 1c. Thirteen of the 16 stx1-positive O104 isolates were from one feedlot. The predominant serotype was O104:H7. Pulsed-field gel electrophoresis analysis indicated that stx1-positive O104:H7 isolates had 62.4% homology to the German outbreak strain and 67.9% to 77.5% homology to human diarrheagenic O104:H7 strains. The 13 isolates obtained from the same feedlot were of the same PFGE subtype with 100% Dice similarity. Although cattle do not harbor the O104:H4 pathotype, they do harbor and shed Shiga toxigenic O104 in the feces and the predominant serotype was O104:H7.     

Antimicrobial Resistance in Escherichia coli Recovered from Feedlot Cattle and Associations with Antimicrobial Use

The objectives of this study were to estimate the prevalence of antimicrobial resistance (AMR) and to investigate the associations between exposures to antimicrobial drugs (AMDs) and AMR in fecal non-type specific Escherichia coli (NTSEC) recovered from a large population of feedlot cattle. Two-stage random sampling was used to select individually identified cattle for enrollment, which were sampled at arrival and then a second time later in the feeding period. Advanced regression techniques were used to estimate resistance prevalences, and to investigate associations between AMD exposures in enrolled cattle and penmates and AMR identified in NTSEC recovered from the second sample set. Resistance was most commonly detected to tetracycline, streptomycin, and sulfisoxazole, and was rarely identified for critically important AMDs. All cattle were exposed to AMDs in feed, and 45% were treated parenterally. While resistance prevalence generally increased during the feeding period, most AMD exposures were not significantly associated with AMR outcomes. Exposures of enrolled cattle to tetracycline were associated with increased resistance to tetracycline and trimethoprim sulfa, while beta-lactam exposures were associated with decreased likelihood of detecting streptomycin resistance. Pen-level AMD exposure measures were not associated with resistance outcomes. These findings suggest that tetracycline treatment of feedlot cattle can be associated with modest increases in risk for recovery of resistant NTSEC, but the numerous treatments with an advanced macrolide (tulathromycin) were not associated with detectable increases in resistance in NTSEC. All cattle were exposed to in-feed treatments of tetracycline and this could limit the ability to identify the full impact of these exposures, but these exposures varied for enrolled cattle varied, providing an opportunity to evaluate a dose response. While AMD exposures were not associated with detectably increased risks for resistance to critically important AMDs, rare resistance outcomes and infrequent exposure to other important AMDs (e.g., cephalosporins) limited our ability to rigorously investigate questions regarding factors that can influence resistance to these important AMDs.     

Effect of Haylage and Monensin Supplementation on Ruminal Bacterial Communities of Feedlot Cattle

The objective of this study was to investigate the ruminal bacterial communities as affected by monensin, haylage, and their interaction of feedlot cattle fed 60 % dried distillers grains with solubles in a replicated 4 × 4 Latin square design. Pyrosequencing analysis of the V1–V3 region (about 500 bp) of 16S rRNA gene from the four dietary treatments (3 treatment plus one control diets) collectively revealed 51 genera of bacteria within 11 phyla. Firmicutes and Bacteroidetes were the first and the second most predominant phyla, respectively, irrespective of the dietary treatments. Monensin supplementation decreased the proportion of Gram-positive Firmicutes while increasing that of Gram-negative Bacteroidetes. However, the monensin supplementation did not reduce the proportion of all genera of Gram-positive bacteria placed within Firmicutes and lowered that of some genera of Gram-negative bacteria placed within Bacteroidetes. Haylage supplementation appeared to attenuate inhibition of monensin on some genera of bacteria. Factors other than monensin and haylage could affect ruminal bacterial communities.     

Factors Associated with the Presence of Coliforms in the Feed and Water of Feedlot Cattle

The objective of this study was to investigate coliform counts in feedlot cattle water and feed rations and their associations with management, climate, fecal material, and water Escherichia coli O157 using a cross-sectional study design. Coliform counts were performed on feed samples from 671 pens on 70 feedlots and on water samples from 702 pens on 72 feedlots in four U.S. states collected between May and August 2001. Management and climate factors were obtained by survey and observation. Month of sampling (higher in May and June), presence of corn silage in the ration (negative association), temperature of the feed 1 in. (ca. 2.5 cm) below the surface at the time of sampling (negative association), and wind velocity at the time of sampling (positive association) were significantly associated with log₁₀ coliform levels in feed. Month of sampling (lower in May versus June July and August), water pH (negative association), and water total solids (positive association) were significantly associated with log₁₀ water coliform levels. Coliform counts in feed and water were not associated with prevalence of E. coli O157 in cattle feces or water. Management risk factors must be interpreted with caution but the results reported here do not support the use of coliform counts as a marker for E. coli O157 contamination of feed or water.     

Simulation of Airborne Microbial Droplet Transport

The framework for a simulation model which describes the dispersion of individual droplets of water containing viable microbes is presented. The model accounts for physical, chemical, biological, and measured meteorological parameters of each droplet at each of many short time steps. Repeating the modeling process for many droplets will simulate a cloud of droplets. The model is compared with the Tulelake, Calif., release in 1988 and found to show very similar patterns of deposition within 30 m (the maximum observation distance of the source. A hypothesis for the survival sequence in the microbe-containing droplets is discussed.     

Diversity and Abundance of Zoonotic Pathogens and Indicators in Manures of Feedlot Cattle in Australia

The occurrence of 10 pathogens and three fecal indicators was assessed by quantitative PCR in manures of Australian feedlot cattle. Most samples tested positive for one or more pathogens. For the dominant pathogens Campylobacter jejuni, Listeria monocytogenes, Giardia spp., Cryptosporidium spp., and eaeA-positive Escherichia coli, 10² to 10⁷ genome copies g⁻¹ (dry weight) manure were recovered.More than 600,000 tons of feedlot cattle manure are generated each year in Australia, which raises concern for potential water, air, and soil contamination (21, 27). Hence, better monitoring and knowledge of the resulting risks are needed (5, 26). Most zoonotic pathogens associated with cattle are well described in the literature, especially those of major health significance, including the bacterial pathogens Campylobacter spp., Listeria monocytogenes, pathogenic Escherichia coli (particularly serotypes O157 and O111), Salmonella enterica, Yersinia spp., Leptospira spp., Coxiella burnetii, Mycobacterium avium subsp. paratuberculosis, and the parasitic protozoa Giardia lamblia and Cryptosporidium parvum (2, 21, 27). While studies of pathogen occurrence in manure are numerous, data suited to quantitatively estimating end user risks are still limited. Few surveys quantify multiple pathogens (11, 12, 14, 28), and none have concurrently measured all 10 above in cattle manure. A further constraint on risk assessment is that most data were generated in North America or Europe, where cli-mate and environment can differ markedly from Australian conditions.Addressing this knowledge gap now appears feasible, as real-time quantitative PCR (qPCR) can be used as an alternative to culture-based methods for quantifying environmental pathogens (7, 23, 29). Improvements in sample preparation and nucleic acid cleanup methods have largely overcome problems associated with the molecular biology-based analysis of fecal matter (22). Further, qPCR can detect stressed, damaged, and otherwise nonculturable cells persisting in a state of dormancy or indeed dead (15, 17, 29). The aim of this paper is to report on a quantitative survey of zoonotic pathogens and indicators in manures from Australian feedlot beef cattle.A total of 128 composited samples (five subsamples each) representing fresh feces (n = 32), pen manure (n = 32), harvested pen manure (n = 28), stockpiled manure (n = 23), composted manure (n = 6), and carcass compost (n = 7) were collected from five cattle feedlots in eastern Australia in the winter/summer of 2009 (13). All samples were assayed for the 10 key pathogens listed above and also fecal indicators (total coliforms, E. coli, and enterococci).     

施用微生物制剂对育蚌水体微生物区系的影响

研究了育蚌水体分别施用微生物制剂利水素与鱼虾菌乐后水样中微生物区系的变化。试验结果表明:施用利水素的水样革兰氏阴性杆菌和嗜水气单胞菌含量分别下降26.67%、20%,芽胞杆菌和表皮葡萄球菌含量分别上升13.33%、26.67%;施用鱼虾菌乐的水样革兰阴性杆菌和嗜水气单胞菌含量分别下降20%、13.33%,芽胞杆菌和表皮葡萄球菌含量分别上升6.67%、13.33%;未施用微生物制剂的水样革兰阴性杆菌和嗜水气单胞菌含量均上升13.33%,芽胞杆菌消失,新增肠杆菌和链球菌。施用微生物制剂利水素和鱼虾菌乐,可有效优化养殖水体微生物种群结构,改良养殖水质环境。     

Molecular Diversity of Methanogens in Feedlot Cattle from Ontario and Prince Edward Island, Canada

The molecular diversity of rumen methanogens in feedlot cattle and the composition of the methanogen populations in these animals from two geographic locations were investigated using 16S rRNA gene libraries prepared from pooled PCR products from 10 animals in Ontario (127 clones) and 10 animals from Prince Edward Island (114 clones). A total of 241 clones were examined, with Methanobrevibacter ruminantium accounting for more than one-third (85 clones) of the clones identified. From these 241 clones, 23 different 16S rRNA phylotypes were identified. Feedlot cattle from Ontario, which were fed a corn-based diet, revealed 11 phylotypes (38 clones) not found in feedlot cattle from Prince Edward Island, whereas the Prince Edward Island cattle, which were fed potato by-products as a finishing diet, had 7 phylotypes (42 clones) not found in cattle from Ontario. Five sequences, representing the remaining 161 clones (67% of the clones), were common in both herds. Of the 23 different sequences, 10 sequences (136 clones) were 89.8 to 100% similar to those from cultivated methanogens belonging to the orders Methanobacteriales, Methanomicrobiales, and Methanosarcinales, and the remaining 13 sequences (105 clones) were 74.1 to 75.8% similar to those from Thermoplasma volcanium and Thermoplasma acidophilum. Overall, nine possible new species were identified from the two clone libraries, including two new species belonging to the order Methanobacteriales and a new genus/species within the order Methanosarcinales. From the present survey, it is difficult to conclude whether the geographical isolation between these two herds or differences between the two finishing diets directly influenced community structure in the rumen. Further studies are warranted to properly assess the differences between these two finishing diets.     

健康人皮肤正常菌群的研究

本研究对我国健康人皮肤正常菌群进行了探讨,发现在健康人前额皮肤上表皮葡萄球菌数为1.6×10~2～1.7×10~7/厘米~2,疮疤丙酸杆菌数为5.3×10~2～4.1×10~7/厘米~2,棒状杆菌数为1.31×10~2～4.1×10~4/厘米~2,真菌为0.17×10~2～6.1×10~3/厘米~2。在全皮标本中疮疱丙酸杆菌数为1.12×10~2～1.7×10~5/厘米~2,表皮葡萄球菌为1.36×10~2～3.9×10~2/厘米~2。表皮标本中,随年龄增加,表皮葡萄球菌有所减少,而金黄色葡萄球菌则增多。男女性皮肤正常菌群的比较中,表皮葡萄球菌、棒状杆菌、疮疱丙酸杆菌男性高于女性,而金黄色葡萄球菌、真菌却女性多于男性,但差异都不显著。全皮标本与表皮标本的比较中,表皮标本中表皮葡萄球菌、疮疱丙酸杆菌、金黄色葡萄球菌、棒状杆菌和真菌数都多于全皮标本,只是上述的后三种菌群的差异显著。     

Diversity and Distribution of Commensal Fecal Escherichia coli Bacteria in Beef Cattle Administered Selected Subtherapeutic Antimicrobials in a Feedlot Setting

Escherichia coli strains isolated from fecal samples were screened to examine changes in phenotypic and genotypic characteristics including antimicrobial susceptibility, clonal type, and carriage of resistance determinants. The goal of this 197-day study was to investigate the influence of administration of chlortetracycline alone (T) or in combination with sulfamethazine (TS) on the development of resistance, dissemination of defined strain types, and prevalence of resistance determinants in feedlot cattle. Inherent tetracycline resistance was detected in cattle with no prior antimicrobial exposure. Antimicrobial administration was not found to be essential for the maintenance of inherently ampicillin-resistant and tetracycline-resistant (Tet^r) E. coli in control animals; however, higher Tet^r E. coli shedding was observed in animals subjected to the two treatments. At day 0, high tetracycline (26.7%), lower sulfamethoxazole-tetracycline (19.2%), and several other resistances were detected, which by the finishing phase (day 197) were restricted to ampicillin-tetracycline (47.5%), tetracycline (31.7%), and ampicillin-tetracycline-sulfamethoxazole (20.8%) from both treated and untreated cattle. Among the determinants, bla_TEM1, tet(A), and sul2 were prevalent at days 0 and 197. Further, E. coli from day 0 showed diverse antibiogram profiles and strain types, which by the finishing phase were limited to up to three, irrespective of the treatment. Some genetically identical strains expressed different phenotypes and harbored diverse determinants, indicating that mobile genetic elements contribute to resistance dissemination. This was supported by an increased linked inheritance of ampicillin and tetracycline resistance genes and prevalence of specific strains at day 197. Animals in the cohort shed increasingly similar genotypes by the finishing phase due to animal-to-animal strain transmission. Thus, characterizing inherent resistance and propagation of cohort-specific strains is crucial for determining antimicrobial resistance in cattle.