E coli Accumulation behind an Obstacle

This paper describes our findings regarding the accumulation of motile bacteria at the rear of a confined obstacle and the physical description of the mechanisms at play. We found that the modification of flow due to the presence of the obstacle produces vorticity that favor the diffusion of bacteria towards the downstream stagnation point. By testing different flow rates, we determined the range in which bacteria accumulate. More interestingly, we observe that hydrodynamic interaction between the bacteria and the top and bottom surface of the microfluidic chip maintain the bacteria in the region where the flow velocity is lower than their own velocity. In the case of non-motile bacteria, this effect is not observed because bacteria follow the streamlines as passive tracers do.

重组体pET-28a-alkB/E.coli降解页岩油泥石油烃的功能研究

为了降解页岩油泥中的石油烃,构建基因工程菌,表达石油烃降解关键酶以提高油泥的降解效果。以Pseudomonas qingdaonensis基因组为模板扩增alkB基因,连接至载体pET-28a,转化至E.coli BL21(DE3)中,SDS-PAGE和Western-blot鉴定表达的外源蛋白。pET-28a-alkB/E.coli处理原油和页岩油泥,采用气相色谱法评估降解效果。发现alkB基因在大肠杆菌中能表达外源蛋白,且14 d原油及页岩油泥的降解率分别为47.5%和47.1%,表明重组体pET-28a-alkB/E.coli具备降解页岩油泥石油烃的功能。

Exploring the modulatory role of bovine lactoferrin on the microbiome and the immune response in healthy and Shiga toxin‑producing E.coli challenged weaned piglets

Background Post-weaned piglets suffer from F18+Escherichia coli(E.coli)infections resulting in post-weaning diar-rhoea or oedema disease.Frequently used management strategies,including colistin and zinc oxide,have contrib-uted to the emergence and spread of antimicrobial resistance.Novel antimicrobials capable of directly interacting with pathogens and modulating the host immune responses are being investigated.Lactoferrin has shown promising results against porcine enterotoxigenic E.coli strains,both in vitro and in vivo.Results We investigated the influence of bovine lactoferrin(bLF)on the microbiome of healthy and infected weaned piglets.Additionally,we assessed whether bLF influenced the immune responses upon Shiga toxin-producing E.coli(STEC)infection.Therefore,2 in vivo trials were conducted:a microbiome trial and a challenge infection trial,using an F18+STEC strain.BLF did not affect theα-andβ-diversity.However,bLF groups showed a higher relative abundance(RA)for the Actinobacteria phylum and the Bifidobacterium genus in the ileal mucosa.When analysing the immune response upon infection,the STEC group exhibited a significant increase in F18-specific IgG serum levels,whereas this response was absent in the bLF group.Conclusion Taken together,the oral administration of bLF did not have a notable impact on theα-andβ-diversity of the gut microbiome in weaned piglets.Nevertheless,it did increase the RA of the Actinobacteria phylum and Bifi-dobacterium genus,which have previously been shown to play an important role in maintaining gut homeostasis.Furthermore,bLF administration during STEC infection resulted in the absence of F18-specific serum IgG responses.

Impact of an oligosaccharide-based polymer on the metabolic profiles and microbial ecology of weanling pigs experimentally infected with a pathogenic E.coli

Background Our previous study has reported that supplementation of oligosaccharide-based polymer enhances gut health and disease resistance of pigs infected with enterotoxigenic E.coli(ETEC)F18 in a manner similar to carbadox.The objective of this study was to investigate the impacts of oligosaccharide-based polymer or antibiotic on the host metabolic profiles and colon microbiota of weaned pigs experimentally infected with ETEC F18.Results Multivariate analysis highlighted the differences in the metabolic profiles of serum and colon digesta which were predominantly found between pigs supplemented with oligosaccharide-based polymer and antibiotic.The relative abundance of metabolic markers of immune responses and nutrient metabolisms,such as amino acids and carbohydrates,were significantly differentiated between the oligosaccharide-based polymer and antibiotic groups(q<0.2 and fold change>2.0).In addition,pigs in antibiotic had a reduced(P<0.05)relative abundance of Lachnospiraceae and Lactobacillaceae,whereas had greater(P<0.05)Clostridiaceae and Streptococcaceae in the colon digesta on d 11 post-inoculation(PI)compared with d 5 PI.Conclusions The impact of oligosaccharide-based polymer on the metabolic and microbial profiles of pigs is not fully understood,and further exploration is needed.However,current research suggest that various mechanisms are involved in the enhanced disease resistance and performance in ETEC-challenged pigs by supplementing this polymer.

Minimizing endogenous cryptic plasmids to construct antibiotic-free expression systems for Escherichia coli Nissle 1917

The probiotic bacterium Escherichia coli Nissle 1917(EcN)holds significant promise for use in clinical and biological industries.However,the reliance on antibiotics to maintain plasmid-borne genes has overshadowed its benefits.In this study,we addressed this issue by engineering the endogenous cryptic plasmids pMUT1 and pMUT2.The non-essential elements were removed to create more stable derivatives pMUT1NR△and pMUT2HBC△.Synthetic promoters by integrating binding motifs on sigma factors were further constructed and applied for expression of Bacteroides thetaiotaomicron heparinaseⅢand the biosynthesis of ectoine.Compared to traditional antibiotic-dependent expression systems,our newly constructed antibiotic-free expression systems offer considerable advantages for clinical and synthetic biology applications.

Characteristics of β-Lactamase Synthesis in E. coli and K. pneumanie Strains in Nosocomial Infections

Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.

The Transport and Persistence of Escherichia coli in Leachate from Poultry Litter Amended Soils

Fecal coliform bacteria such as Escherichia coli (E. coli) are one of the main sources of groundwater pollution. An assessment of the transport and Persistence of E. coli in poultry litter amended Decatur silty Clay soil and Hartsells Sandy soil was conducted using soil columns and simulated groundwater leaching. Enumeration of initial E. coli was determined to range from 2.851 × 103 to 3.044 × 103 CFU per gram of soil. These results have been used in a batch study to determine the persistence rate of E. coli in Decatur silty Clay soil and Hartsells Sandy soil. Results prove that E. coli survival growth rate increases for clay soil later than and at a higher rate than sandy soil. The column study has determined that E. coli was transported at a rate of 3.7 × 106 CFU for Decatur silty loam and 6.3 × 106 CFU for Hartsells sandy per gram of soil. Further, linear regression analysis predictions show higher porosity and soil moisture content affect transport, and Hartsells sandy soil has higher transport of E. coli due to its higher porosity and lower volumetric water content.

Growth Inhibition of Escherichia coli and Staphylococcus epidermidis from Various Types of Honey

Honey has long been considered a wound treatment used to keep cuts and other epidermal injuries clean. This study tested that claim by comparing manuka honey used in medicine today, local unprocessed honey taken straight from a hive, and pasteurized honey found at a store, on strains of E. coli and S. epidermidis. The study evaluated the effects these honeys had on bacterial growth to determine which had the greatest inhibition of bacterial growth. To determine this, plates streaked with strains of E. coli or S. epidermidis bacteria and agar wells filled with one of the honeys were incubated and subsequently the diameter of the zone of inhibition was measured. After 20 trials using each honey and bacteria type, manuka and unprocessed were shown to have a statistically significant advantage over the pasteurized honey at inhibiting the growth of E. coli and S. epidermidis, though it was variable whether manuka had an advantage over the unprocessed honey.

Evaluating the Potential of Nitrofurantoin and Fosfomycin for E.coli UTIs: A Susceptibility Study

This study was designed to find the susceptibility of Nitrofurantoin and Fosfomycin among urinary isolates of Escherichia.coli.Four hundred(400)urine samples were collected for susceptibility of nitrofurantoin and fosfomycin among urinary isolates of E.coli.All indoor and outdoor patients'urinary samples yielded growth of E.coli.Mid-stream urine specimens were inoculated on blood agar and CLED agar and incubated at 35±2°C.Growth was observed,and Escherichia coli was identified by Gram staining,Catalase,Motility test and API 20E(Bio murex)as per standard procedure.Antimicrobial susceptibility testing of isolates for nitrofurantoin and fosfomycin was carried out by the modified Kirby-Bauer disc diffusion method according to CLSI guidelines ATCC 25922.E.coli was used as a quality control strain.A total of 400 samples were tested susceptibility of nitrofurantoin and fosfomycin among urinary isolates of E.coli during this period.A total of 400 samples yielded the growth of E.coli,out of which 178(44.5%)were male and 222(55.5%)were female samples.Among males,18(10%)were tolerant to nitrofurantoin,and 2(1.1%)were tolerant to fosfomycin.Among females,9(4.09%)were susceptible to nitrofurantoin while 6(2.72%)were susceptible to fosfomycin.Among age groups below 45 years old,6(4.76%)were tolerant to nitrofurantoin,and 2(1.58%)were sensitive to fosfomycin.Between 46-66 years old,4(2.81%)were sensitive to nitrofurantoin,and 3(2.11%)were sensitive to fosfomycin.Between 67-90 years old,17(12.87%)were sensitive to nitrofurantoin,and 4(3.03%)were tolerant to fosfomycin.Fosfomycin and nitrofurantoin showed good susceptibility in urinary isolates of E.coli and can be used empirically in our setup.

Evidence and Potential Antibacterial Mechanism of Chinese Traditional Medicine Compounds for the Development of E. coli

Astragalus membranaceus (huangqi), Allium sativum (garlic), Cinnamomum cassia (cinnamon), and Dolichos lablab L. (white hyacinth bean) are the traditional Chinese herbs that were used in prescriptions in treating diarrhea caused by bacterial infection. These herbs are relatively safe for use and investigation. This study aimed to investigate the effects of Astragalus membranaceus, Allium sativum, Cinnamomum cassia, and Dolichos lablab L. on the metabolism of Escherichia coli (E. coli). The growth rate of E. coli was monitored under the influence of each herb, revealing that Astragalus membranaceus and Allium sativum exhibited significant antibacterial activity, whereas Cinnamomum cassia and Dolichos lablab L. demonstrated moderate inhibitory effects on E. coli growth. Further inhibition zone testing allowed for the evaluation of each herb’s potency and the number of generations required for E. coli to develop resistance. Additionally, the impact of the four herbs on the expression of outer membrane protein A (OmpA) in E. coli was examined by using qPCR. The findings revealed that Astragalus membranaceus acted as a sustainable bactericide by inhibiting the growth and metabolism of E. coli MG1655 through the suppression of OmpA expression. These results suggest that Astragalus membranaceus has potential as a natural antimicrobial agent for treating E. coli infections.

Genotyping Characteristics of Human Fecal Escherichia coli and Their Association with Multidrug Resistance in Miyun District, Beijing

Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.

Escherichia coli Pathotypes in Children with Acute Diarrhea in an Informal Settlement in Nairobi, Kenya

Diarrhea is among the leading causes of morbidity and mortality in children aged Escherichia coli (DEC) accounts for 30% - 40% of childhood diarrhea cases. To identify the pathotypes involved in diarrheal outbreaks in Kenya, we analyzed archived E. coli isolates from children E. coli confirmation and antimicrobial susceptibility testing were done using the VITEK®2 instrument. Pathotype identification was performed via conventional polymerase chain reaction. Of 175 E. coli isolates, 48 (27%) were DEC pathotypes, with enteroaggregative E. coli (EAEC) predominating (71%, 34/48). Enterohemorrhagic (EHEC) and enteropathogenic E. coli (EPEC) represented 19% and 10% of isolates, respectively. Enteroinvasive and enterotoxigenic pathotypes were not identified. All DEC isolates were susceptible to amikacin, ertapenem, imipenem, meropenem and tigecycline. Conversely, most (>80%) isolates were resistant to ampicillin, ampicillin-sulbactam and sulfamethoxazole-trimethoprim. Half of all EAEC and EPEC strains were resistant to cefazolin while half of EHEC isolates were resistant to ciprofloxacin and moxifloxacin. In total, 18 resistance phenotypes were identified with “ampicillin-cefazolin-ampicillin/ sulbactam-sulfamethoxazole/trimethoprim” predominating (33%, 16/48). The majority (81%) of DEC isolates were multidrug-resistant, with extended-spectrum beta-lactamase production identified in 8% of these isolates. This study highlights the predominance of Enteroaggregative E. coli and multidrug resistance of DEC pathotypes. Studying the epidemiology of diarrheal disease and antimicrobial resistance surveillance, will aid in identifying dominant etiological agents of diarrhea and newly emerging resistant strains in informal settlements.

2种氟喹诺酮类抗生素与群体感应抑制剂对E.coli的联合毒性效应

抗生素滥用带来严重的细菌耐药性,威胁生态环境和人体健康。群体感应抑制剂(quorum sensing inhibitors,QSIs)作为一种理论上难以引发细菌耐药性的新型潜在抗生素替代品,被建议单独使用或与传统抗生素联合使用。因此,考察抗生素与QSIs联合作用效应及其作用机理对其在环境中可能产生的联合暴露风险评估具有重要的参考意义。以应用较广泛的2种氟喹诺酮类药物氧氟沙星(ofloxacin,OFL)、左氧氟沙星(levofloxacin,LEV)和1种新型抗菌剂群体感应抑制剂4-羟基-2,5-二甲基-3(2H)呋喃酮(4-hydroxy-2,5-dimethyl-3(2H)-furanone,HDMF)为研究对象,运用直接均分法和均匀设计射线法分别设计3个二元和1个三元混合物体系,每个体系包含5条具有不同组分浓度比的射线。应用时间毒性微板分析法测定3种药物及其混合物体系对大肠杆菌(Escherichia coli,E.coli)的毒性,应用拟合归零法分析混合物的毒性相互作用及相互作用强度,采用分子间对接技术来探讨可能存在的作用机理。结果表明,HDMF、OFL、LEV对E.coli均具有浓度、时间依赖毒性,以半数效应浓度负对数为毒性指标,3种药物在同一暴露时间毒性顺序:LEV>OFL>HDMF。3种药物的二元混合物体系相互作用类型有拮抗/协同作用,而三元混合物体系的作用类型为协同作用,且作用类型和强度受混合物组分、暴露时间和浓度影响。氟喹诺酮类药物混合物体系中,因药物竞争结合蛋白点位而呈现出拮抗作用。在氟喹诺酮类药物和QSIs混合体系中,QSIs会破坏细菌的生物膜,使氟喹诺酮类药物更容易接触细菌造成损伤,从而呈现协同作用。但随着暴露时间的延长,氟喹诺酮类药物会对DNA造成损伤进而减少QSIs作用蛋白的产生,呈现出拮抗作用。

Detection of aac(3)IIc, aac(6)Ib, armA Genes Coding for Escherichia coli Resistance to Aminoglycosides in Burkina Faso

Background and Prupose: Antibiotic resistance is a major global health concern. In addition to the existing data on the prevalence of bacterial resistance to antibiotics, there are patchy data on bacterial resistance to aminoglycosides in Burkina Faso. In this study, we determined the prevalence of aminoglycoside resistance genes in E. coli, including aac(3)-IIc, aac(6)-Ib and armA in Ouagadougou, and determined which antibiotics in this class are most affected by resistance. Material and Methods: This study was conducted on 216 E. coli strains collected from the biomedical analysis laboratories of Saint Camille and Schiphra hospitals. E. coli strains were isolated from pus and urine samples collected between September 2018 and January 2019. Antibiotic susceptibility testing was performed using aminoglycosides, β-lactams, fluoroquinolones, and sulfonamides. Aminoglycoside resistance genes were detected in strains with at least one aminoglycoside resistance gene using conventional/multiplex PCR. Results: Aminoglycoside resistance was observed in 46.8% (101/216) of strains. The resistance rates were respectively 45.37% for Tobramycin, 32.40% for Gentamicin, 14.81% for Kanamycin, 2.31% for Netilmicin, 1.84% for Neomycin, and 0.46% for Amikacin. PCR showed that 86 strains (85.15%) possessed the aac(3)-IIc gene, 71 strains or 70.30%) possessed the aac(6’)-Ib gene, and nine strains (8.91%) possessed the armA gene. Conclusion: Aminoglycoside resistance in pathogenic E. coli strains is mainly due to the presence of the aac(3’)-IIc and aac(6’)-Ib genes. The presence of armA was first reported in Burkina Faso. Netilmicin, Neomycin and Amikacin are good therapeutic options for treating urinary tract and pus-forming infections.

De Novo Synthesis of Biopaint Using Transformed Bacteria: Analysis of Spectral Intensity Trends and Comparison to Commercial Paint

Background: Commercial paint pigments contain toxic heavy metals that harm humans and pollute the environment. To mitigate these harms, ecologically safe pigments are necessary. Objective: This experiment aims to create a biopaint de-novo using transformed Escherichia coli bacteria and compare it to commercial paint. Methods: Genetically engineered E. coli bacteria producing magenta pigment were grown in petri dishes. The pigment protein was extracted, filtered, and dehydrated into a crystalline powder. This was mixed with acrylic medium to make biopaint. The biopaint and commercial paint were applied on acrylic paper;red, green, blue, and total spectral intensities were measured daily under different testing conditions. Spectral intensity variability was measured and compared using the Coefficient of Variation (CV). Trends in spectral intensity were analyzed using regression analysis. Results: The differences in the CV of biopaint to commercial paint were less than 20% under all testing conditions. Spectral intensities for both biopaint and commercial paint did not show any significant change during the testing period under the conditions of room temperature, heat, and humidity. However, under the cold testing condition, biopaint showed a slight but statistically significant (p-value Conclusion: This experiment proves that E. coli-derived pigments can be used to make biopaint which has a similar durability to commercial paint as measured by the spectral intensities.

Performance Parameters:Demobilization Antibiotic Resistant Bacteria(ARB)and Carrying Genes(ARG)in Wastewater Disinfection

The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.

重组E.coli工程菌高密度培养生产人源型胶原蛋白

Several technical parameters were studied during the fermentation of recombinant E.coli for the production of collagen-like biopolymer.The effects of dissolved oxygen as well as glucose concentration on fermentation were observed.The OD 600 value could reach 98 when dissolved oxygen was controlled at 50% and glucose around 1%.The production of human-like collagen with a yield of 29.4% was obtained.

免疫磁分离技术在E.coli O157∶H7检测中的应用

免疫磁分离(i mmunomagnetic separation)技术因其具有选择性好、特异性强、能起到浓缩的作用,已与其他快速检测方法如电化学、光学等方法连用,应用于食品、环境卫生检测等领域。免疫磁分离技术是目前最有推广价值的技术之一。文章通过比较不同的E.coli O157∶H7-免疫磁珠(immunomagnetic beads,I MB)浓度配比、E.coli O157∶H7与Bacillus subtilis不同的体积比下的免疫磁分离的捕获率,得出当E.coli O157∶H7-I MB浓度配比为1∶30时,捕获率近100%,即所有的目标菌均可被捕获到;在总体积不变、IMB的加入量一定的情况下,随着Bacillus subtilis比例的增加,捕获率出现先下降后上升的情况。同时,将IMS与ATP生物发光法结合起来,对不同浓度的E.coliO157∶H7进行了检测,得出该方法与传统的平板培养法具有很好的线性相关性,则R2=0.9882,检测限可低达102CFU.mL-1。

中药三黄汤、小檗碱对E.coli生长抑制作用与庆大霉素的比较

庆大霉素对E .coli的抑菌作用强 ,试管稀释法、琼脂稀释法和平板抑菌圈法抑菌试验得到一致的MIC(3～5 μg/mL) ;三黄汤、小檗碱抑菌作用弱而稳定 ,试管稀释法测得的MIC分别为 5 0 0mg/mL和 2 .5mg/mL ,而用平板抑菌圈法得不到明显的抑菌圈 .在亚MIC药物液体分批培养时 ,庆大霉素抑菌曲线起初 2h迅速下降 ,而后回升到初始浓度 ,而三黄汤抑菌曲线平缓稳定 ,说明中药和抗生素的抑菌机制明显不同 .庆大霉素与小檗碱混合使用时 ,与庆大霉素单独使用相近 ,而与三黄混合使用时 ,则主要表现三黄汤的抑菌作用 .因此中西药结合时需要慎用 .在接近MIC药物培养基中连续传代 2 0次后 ,庆大霉素MIC提高 8倍多 ,而三黄汤和小檗碱MIC无显著变化 ,无抗药性产生 ,也不产生对庆大霉素的交叉抗药性 .研究结果还表明 ,在 1/ 4MIC三黄汤中连续传代 2 0次 ,能消除E .coli已形成的庆大霉素抗性 ,这为解决抗生素抗药性提供了线索 .图 4参 2

养殖场空气中E.coli磺胺类抗生素的抗性

本文从养殖场空气中分离出360株E.coli(大肠杆菌,Escherichia coli),应用肉汤微量稀释法和PCR方法,分离磺胺甲唑敏感菌株,检测抗生素抗性和抗性基因.在分离的E.coli中,对磺胺甲唑敏感菌株为95株(26.4%),有48株含有青霉素、氯霉素、四环素、环丙沙星、庆大霉素和利福平的抗性,而47株未含有抗性.其中,7株菌株含有1种抗生素抗性、11株菌株含有2种抗生素抗性、17株菌株含有3种抗生素抗性、6株菌株含有4种抗生素抗性、4株菌株含有5种抗生素抗性、3株菌株含有6种抗生素抗性.对抗生素的耐受能力依次为:氯霉素、青霉素、四环素、环丙沙星、庆大霉素、利福平.磺胺甲唑敏感菌株共检出163个抗性基因,sul1、int1、sul2、Int2、sul3检出数量依次为49、44、29、20和19;含一种、二种、三种、四种、五种抗性基因菌株分别为45、22、10、7、2;但有6株未检测出抗性基因.结果表明养殖场建场时间、抗生素使用、养殖规模等与抗生素抗性菌的抗性呈正相关;养殖场空气中分离的E.coli抗生素抗性较高,且具有多重抗性;抗生素抗性的表现型与其基因型之间出现不完全吻合现象.