Antimicrobial resistance of Escherichia coli isolates from broiler chickens and humans

Background

Inguinal hernias are usually caused by a congenital defect, which occurs as a weakness of the inguinal canal. Porcine β-glucuronidase gene (GUSB) was chosen as functional candidate gene because of its involvement in degradation of hyaluronan within gubernacular tissue during descent of testes. Since a genome-wide linkage analysis approach has shown evidence that two regions on porcine chromosome 3 (SSC 3) are involved in the inheritance of hernia inguinalis/scrotalis in German pig breeds, GUSB also attained status as a positional candidate gene by its localization within a hernia-associated chromosomal region.

Results

A contig spanning 17,157 bp, which contains the entire GUSB, was assembled. Comparative sequence analyses were conducted for the GUSB gene locus. Single nucleotide polymorphisms (SNPs) located within the coding region of GUSB were genotyped in 512 animals. Results of transmission disequilibrium test (TDT) for two out of a total of five detected SNPs gave no significant association with the outcome of hernia in pigs.

Conclusion

On the basis of our studies we are able to exclude the two analyzed SNPs within the porcine GUSB gene as causative for the transmission of inguinal hernia.     

Minimum inhibitory concentrations of intestinal Escherichia coli from broiler chickens after oral administration of apramycin

This study describes the influence of apramycin on minimum inhibitory concentrations (MIC) of intestinal Escherichia coli in young broiler chickens, after oral administration of the antibiotic at a dosage equivalent to a prophylactic course of treatment for 10 d. The bacteria were isolated from cloacal swabs and caecal contents. MICs were determined by agar dilution procedures. MIC of apramycin for the investigated strains ranged from 1 μg ml^-1 to 16 μg ml^-1. Strains obtained from undosed birds mainly had MIC values of 1 μg ml^-1. MIC values of 8 μg ml^-1 or more were recorded only among isolates obtained from chickens which had received apramycin. Administration of apramycin resulted in a slight but statistically significant increase in the average MIC. Statistically higher average MICs were recorded among isolates from cloacal swabs 10 d after withdrawal until the end of the experiment. For strains from caecal contents, this was demonstrated only on one sampling occasion, 15 d after withdrawal.     

Isolation of potentially pathogenic Escherichia coli O157:H7 from the Ganges River

Escherichia coli serotype O157:H7 was detected among bacteria collected from the Ganges River. O157:H7 isolates tested positive for stx(1), stx(2), and eae gene sequences. Identification of potentially pathogenic isolates from extensively used source water indicates that O157:H7 may be a significant but as yet underacknowledged public health concern in India.     

Characterization of florfenicol resistance among calf pathogenic Escherichia coli

Three floR genes were cloned from calf pathogenic Escherichia coli strains, and the efflux-mediated accumulation of florfenicol in the floR gene-JM109 E. coli system was determined by HPLC. The floR genes resulted in a 1356-bp fragment covering the ORF in region 66-1280 coding for 404 amino acids. The common motifs of 12-transmembrane segments efflux pumps family were conserved in the deduced floR amino acid sequences. HPLC results indicated a significant difference in florfenicol accumulation between florfenicol-resistant strains and the susceptible strains, which was almost reversed by the addition of a proton motive force blocker. These results suggest that the florfenicol resistance mediated by the floR gene involves active efflux of florfenicol.     

Trypsin inhibitor,mineral availability,and performance of broiler chickens fed on diets based on rice bran

Trypsin inhibitor in rice bran was inactivated by moist heat, but not by dry heating or treatments with 0.1% H₂SO₄, 0.1% NaOH or 0.1% NaCl. Heating rice bran could not improve its growth promotion value in the diet of broilers, which was related to the feed intake. Groundnut meal was the major protein supplement in the diets. Rice bran diets did not affect weight of pancreas (1.45–1.50 g/kg body weight). Use of ⁴⁵Ca revealed that availability of calcium on a rice bran diet was lower than on a maize-based diet. A similar effect on ⁵⁹Fe-availability was noted, although this result needs confirmation. Lack of differences in weight of thyroid glands and uptake of ¹³¹I by thyroids of birds on maize- and rice bran-based diets indicated the absence of any goitrogenic substance in the rice bran.     

Low airborne tenacity and spread of ESBL-/AmpC-producing Escherichia coli from fertilized soil by wind erosion

ESBL-/AmpC-producing Escherichia coli from organic fertilizers were previously detected on soil surfaces of arable land and might be emitted by wind erosion. To investigate this potential environmental transmission path, we exposed ESBL-/AmpC-positive chicken litter, incorporated in agricultural soils, to different wind velocities in a wind tunnel and took air samples for microbiological analysis. No data exist concerning the airborne tenacity of ESBL-/AmpC-producing E. coli. Therefore, we explored the tenacity of two ESBL/AmpC E. coli strains and E. coli K12 in aerosol chamber experiments at different environmental conditions. In the wind tunnel, ESBL/AmpC-producing E. coli were detected in none of the air samples (n = 66). Non-resistant E. coli were qualitatively detected in 40.7% of air samples taken at wind velocities exceeding 7.3 m s⁻¹. Significantly increased emission of total viable bacteria with increasing wind velocity was observed. In the aerosol chamber trials, recovery rates of airborne E. coli ranged from 0.003% to 2.8%, indicating a low airborne tenacity. Concluding, an emission of ESBL/AmpC E. coli by wind erosion in relevant concentrations appears unlikely because of the low concentration in chicken litter compared with non-resistant E. coli and their low airborne tenacity, proven in the aerosol chamber trials.     

Influence of bacteriocin in the control of Escherichia coli infection of broiler chickens in Nigeria

One hundred broiler chickens were divided into four groups. Group A was untreated and challenged with E. coli 02:KH6; group B was infected and treated with bacteriocin in their drinking water; group C was infected and treated by administration of Lactobacillus plantarum F1 culture in skimmed milk, and group D acted as a control. Their weight, feed intake, clinical signs, microscopic lesions, E. coli re-isolation and serum biochemistry were compared. Groups B and C showed fewer symptoms and gross lesions than those from group A, while body weight and feed intakes were similar to the control group. E. coli 02:KH6 was re-isolated in 60% of the livers from group A, compared to 8 and 12% of the livers from group B and C respectively. There was significant increase in the levels of total protein (3.78 ± 0.05 g/100 ml) and globulins (2.53 ± 0.03 g/100 ml) in group A compared to groups B and C. The cholesterol levels in group A (112.56 ± 0.15 mg/100 ml) were significantly reduced compared to those of groups B and C which had 127.25 ± 0.14 and 128.73 ± 0.13 mg/100 ml respectively. The study provides evidence of the potential therapeutic efficacy of bacteriocin in the control of an experimental E. coli infection in broiler chickens.     

The survival of Escherichia coli O157:H7 in slurry from cattle fed different diets

AIMS: The survival characteristics of Escherichia Coli O157:H7 were investigated in bovine slurry from cattle fed two different diets: (i) silage and (ii) silage + concentrates. METHODS AND RESULTS: Slurry samples collected from freshly-agitated tanks were inoculated at a level of log10 6.0 cfu g(-1) and stored in the laboratory at 10 degrees C. Over a 12 week storage period, a 3.5 and 5.5 log reduction was observed in slurry from cattle fed a silage and silage plus concentrate diet, respectively. CONCLUSIONS: The persistence of E. coli O157:H7 in slurry over a 3 month storage period indicates its potential for transmitting the organism back into the environment. SIGNIFICANCE AND IMPACT OF THE STUDY: The discussion concludes however, that despite pathogen survival in slurry, it may not represent a major source of transmission in the farm environment.     

Photoperiodic requirements for LH release in juvenile broiler and egg-laying strains of domestic chickens fed ad libitum or restricted diets

Photoperiodic response curves for LH release were obtained for juvenile female domestic chickens at 8 weeks of age by measuring changes in plasma LH concentrations after increasing the daily photoperiod from 8 to 10.5, 12.75, 15.25, 17.75 or 20 h. The birds were bred either for meat production (broiler) or commercial egg-laying and were fed ad libitum or a restricted diet, similar to that used under commercial conditions. Ovarian and oviduct growth was stimulated by 2 weeks after transfer to 20 h light/day in the dwarf broiler strain, irrespective of the dietary treatment, but not in birds of the egg-laying strain. Baseline concentrations of plasma LH were higher in the egg-laying than in the dwarf broiler strain birds. A significant effect of dietary treatment was observed on the changes in concentration of plasma LH in the nonphotostimulated dwarf broiler, but not in the egg-laying bird. There was no significant interaction between dietary treatment and photoinduced LH release in birds of either strain. The shortest photoperiod needed to stimulate LH release (critical daylength) was less than 10.5 h in the dwarf broilers and between 10.5 and 12.75 h in the egg-laying birds. The shortest photoperiod needed to stimulate the maximum release of LH (saturation daylength) was between 10.5 and 12.75 h in the dwarf broiler strain. The saturation daylength in birds of the egg-laying strain was longer, being between 12.75 and 15.25 h.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genotypic analyses of Escherichia coli isolated from chickens with colibacillosis and apparently healthy chickens in Japan

A genotypic comparison using pulsed-field gel electrophoresis (PFGE), amplified ribosomal restriction analysis (ARDRA) as well as PCRs targeting virulence associated genes reported elsewhere in avian pathogenic Escherichia coli(APEC) was made between E. coli strains isolated from chickens with colibacillosis and those from the feces of apparently healthy chickens in Japan. The majority (67%) of clinical isolates belonged to a certain phylogenetic ARDRA but not PFGE cluster, with virulence-related genes carried by ColV plasmid being markedly prevalent. The result suggests that APEC strains originated from the same "ancestor" in the course of E. coli evolution.     

Probability of recovering pathogenic Escherichia coli from foods

The probability of recovering pathogenic Escherichia coli from food by the Bacteriological Analytical Manual method was determined by the effects of several factors: the number of strains per food, the ability of pathogenic strains to survive enrichment, and the frequency of plasmid loss during enrichment. Biochemical patterns indicated the presence of about six E. coli strains per food sample. About half of the strains isolated from humans did not survive enrichment. Among those which grew, plasmid loss, as determined by gel electrophoresis and DNA colony hybridization, ranged from 20 to 95%. The combined effects of failure to survive enrichment and plasmid loss decreased the relative numbers of these strains and reduced the chance of detecting pathogens. To counteract this tendency and obtain a 90 to 95% probability off recovering a given pathogenic strain, 40 to 50 colonies per food sample should be picked during the routine testing of foods.     

Characterization of antimicrobial resistance among Escherichia coli isolates from chickens in China between 2001 and 2006

Escherichia coli is a common commensal bacterium and is regarded as a good indicator organism for antimicrobial resistance for a wide range of bacteria in the community and on farms. Antimicrobial resistance of E. coli isolated from chickens from 49 farms in China between 2001 and 2006 was studied. A total of 536 E. coli isolates were collected, and minimal inhibitory concentrations (MICs) of eight antimicrobials were determined by the broth microdilution method. Isolates exhibited high levels of resistance to ampicillin (80.2%), doxycycline (75.0%) and enrofloxacin (67.5%). Relatively lower resistance rates to cephalothin (32.8%), cefazolin (17.0%) and amikacin (6.5%) were observed. Strains were comparatively susceptible to colistin (MIC(50)=1 mug mL(-1)). A marked increase in isolates with elevated MICs for florfenicol was observed over the study period. Therefore, five resistance genes leading to the dissemination of phenicol resistance in the isolates (n=113) with florfenicol MICs>/=32 mug mL(-1) were analyzed. The gene floR was the most prevalent resistance gene and was detected in 92% of the 113 isolates, followed by the cmlA (53%), catA1 (23%) and catA2 (10%) genes. catA3 was not detected in these isolates. Eight isolates with florfenicol MICs=32 mug mL(-1) and one with MIC=64 mug mL(-1) were negative for the floR gene.     

Impact of antimicrobial usage on antimicrobial resistance in commensal Escherichia coli strains colonizing broiler chickens

Escherichia coli strains isolated from commercial broilers and an experimental flock of chickens were screened to determine phenotypic expression of antimicrobial resistance and carriage of drug resistance determinants. The goal of this study was to investigate the influence of oxytetracycline, sarafloxacin, and enrofloxacin administration on the distribution of resistance determinants and strain types among intestinal commensal E. coli strains isolated from broiler chickens. We detected a high prevalence of resistance to drugs such as tetracycline (36 to 97%), sulfonamides (50 to 100%), and streptomycin (53 to 100%) in E. coli isolates from treated and untreated flocks. These isolates also had a high prevalence of class 1 integron carriage, and most of them possessed the streptomycin resistance cassette, aadA1. In order to investigate the contribution of E. coli strain distribution to the prevalence of antimicrobial resistance and the resistance determinants, isolates from each flock were DNA fingerprinted by enterobacterial repetitive intergenic consensus sequence (ERIC) PCR. Although very diverse E. coli strain types were detected, four ERIC strain types were present on all of the commercial broiler farms, and two of the strains were also found in the experimental flocks. Each E. coli strain consisted of both susceptible and antimicrobial agent-resistant isolates. In some instances, isolates of the same E. coli strain expressed the same drug resistance patterns although they harbored different tet determinants or streptomycin resistance genes. Therefore, drug resistance patterns could not be explained solely by strain prevalence, indicating that mobile elements contributed significantly to the prevalence of resistance.     

Potential effect of cattle diets on the transmission of pathogenic Escherichia coli to humans

Grain feeding seems to promote the growth and acid resistance of Escherichia coli in fattening beef cattle, and acid-resistant E. coli are more likely to survive the human gastric stomach. When cattle were fed hay for only five days, the number and acid resistance of E. coli decreased dramatically.     

Phage typing of Escherichia coli isolated from chickens.

Ten different bacteriophages were isolated from untreated city sewage water. These phages were stable at 57 degrees C for 40 min. A modified agar layer technique was used to obtain high titre phages. Ninety-four of a stock of 101 cultures of Escherichia coli, which were isolated from inflamed portions of intestines of chickens, were lysed by one or more of these phages. The E. coli of a known serological grouping were phage typed.     

Sources of variation in the ampicillin-resistant Escherichia coli concentration in the feces of organic broiler chickens

Currently, there are limited published data for the population dynamics of antimicrobial-resistant commensal bacteria. This study was designed to evaluate both the proportions of the Escherichia coli populations that are resistant to ampicillin at the level of the individual chicken on commercial broiler farms and the feasibility of obtaining repeated measures of fecal E. coli concentrations. Short-term temporal variation in the concentration of fecal E. coli was investigated, and a preliminary assessment was made of potential factors involved in the shedding of high numbers of ampicillin-resistant E. coli by growing birds in the absence of the use of antimicrobial drugs. Multilevel linear regression modeling revealed that the largest component of random variation in log-transformed fecal E. coli concentrations was seen between sampling occasions for individual birds. The incorporation of fixed effects into the model demonstrated that the older, heavier birds in the study were significantly more likely (P = 0.0003) to shed higher numbers of ampicillin-resistant E. coli. This association between increasing weight and high shedding was not seen for the total fecal E. coli population (P = 0.71). This implies that, in the absence of the administration of antimicrobial drugs, the proportion of fecal E. coli that was resistant to ampicillin increased as the birds grew. This study has shown that it is possible to collect quantitative microbiological data on broiler farms and that such data could make valuable contributions to risk assessments concerning the transfer of resistant bacteria between animal and human populations.     

绵羊肺源性致病性大肠杆菌的分离与鉴定

【目的】近年来,羊呼吸系统疾病日益频发,由肠外致病性大肠杆菌感染引起的呼吸道疾病也日渐增多,给养羊业带来了一定经济损失。本文旨在确定新疆石河子地区某羊场表现为呼吸道感染症状的病死羔羊的细菌性病原及其特性。【方法】采用细菌常规分离鉴定结合16S rRNA基因序列分析的方法从发病羔羊的肺脏中分离鉴定细菌,并对分离株进行药敏试验、特异基因PCR检测、小鼠致病性试验及肺脏组织的病理学观察。【结果】从病死羔羊肺脏组织分离得到一株致病性大肠杆菌,该分离株呈多重耐药现象,检测到iutA、fyuA和ireA三种毒力基因;病变肺脏肺泡壁毛细血管充血,界限不清,支气管管腔充血,周围淋巴细胞浸润、增生。【结论】从病死羔羊肺中分离的细菌性病原是肠外致病性大肠杆菌(ExPEC)。