Multidrug-Resistant of Escherichia coli and Salmonella spp. Strains in Chicken Feces Intended for Consumption in Open Spaces of Ouagadougou, Burkina Faso

Resistant bacteria can be transmitted to humans through feces or contaminated meat from local chickens. Bacterial strains were isolated from the intestinal contents of 400 local chicken samples from various sales sites. These strains were then characterized using bacteriological and biochemical methods to identify resistant strains. In a study conducted in Ouagadougou, we systematically collected chicken fecal samples from 20 locations across the city, followed by isolation and identification of Salmonella spp. using specific enrichment and culture methods, as well as Escherichia coli. Bacterial strains were characterized using antibiotic resistance profiles were determined through agar diffusion tests, revealing sensitivity or resistance to a range of antibiotics based on established scientific criteria. The results showed that out of the 400 samples collected, 81.25% and 63.5% were contaminated by Escherichia coli and Salmonella spp., respectively. Among these, 86.15% of identified Escherichia coli and 50.78% of Salmonella spp. displayed resistance to at least one tested antibiotic. Among 280 Escherichia coli isolates identified resistant to at least one antibiotic, 31.07% were resistant to cefotaxime (CTX), 20.35% to ceftazidime (CAZ), 21.07% to ceftriaxone (CTR), 75% to amoxicillin clavulanic acid (AMC), 23.57% aztreoname (ATM) and 27.14% were resistant to imipenem (IMP). In the case of the 129 Salmonella spp. isolates resistant to at least one tested antibiotic, 34.88% were resistant to CTX;41.08% to CAZ;35.65% to CTR, 92% to AMC, 39.53% to ATM and finally 47.28% were resistant to IMP. Our study revealed high prevalence of resistance in bacterial strains isolated from local chickens sold outdoors in Ouagadougou. These findings raise significant public health concerns, due to the possible transmission of these resistant strains to humans through the consumption of contaminated meat, thus complicating the treatment of bacterial infections.

PCR Detection of Pilus-associated Genes and Serotype Identification of Pathogenic Escherichia coli Isolated from Chickens in the Jidong Area

[ Objective] This study aimed to explore the presence of type I pill （fimC gene） and P pill （papC gene） and identify the serotype of pathogenic E. coli isolated from chickens in the Jidong Area. [ Method] Type I pill （fimC gene） and P pill （papC gene） were detected by PCR. The serotype was identified by con- ventional agglutination test. [ Result ] The results showed that 100% of chicken-derived E. coil strains expressed type I pill （fimC gene） ; 39.1% （9/23） of chick- en-derived E. coli strains expressed P pill （papC gene）. In addition, 23 isolates of chicken-derived E. coil were assigned to 14 O serotypes, including O78, O93, O 45, O101, O38, O88, O24, O1, O163, O53, O15, O87, O34 and O29, among which O78 was the dominant serotype that accounted for 42.8% （6/14） of the total strain number. [ Conclusion] Chicken-derived E. coli strains in the Jidong Area belonged to 14 serotypes, and 078 was the dominant serotype; 83.3% of 078 serotvDe E. coli strains expressed both tvDe I Dill and P Dill.

Antibiotic Sensitivity Test and Detection of Sulfonamide Resistance Gene Sul2 in Escherichia coli Isolates from Swine

[ Objective] This study aimed to analyze antibiotic sensitivity and detect sulfonamide resistance gene Sul2 in 17 Escherichia coli isolates from swine. [ Method] The antibiotic sensitivity of 17 E. coil isolates from swine was analyzed with Kirby-Bauer disk diffusion method. Sulfonamide resistance gene Sul2 was detected by PCR amplification with the extracted genomic DNA as a template. [ Result] The 17 swine-derived E. coli isolates from different regions were resistant to various antibiotics and exhibited different multi-antibiotic resistance phenotypes, including nine isolates resistant to sulfamethoxazole, seven isolates resistant to oxacillin, ten isolates resistant to cefazolin and eight isolates resistant to erythromycin. Sulfonamide resistance gene Sul2 was successfully amplified from genomic DNA of E. coli isolates. The PCR results were basically consistent with antibiotic resistance phenotypes of these strains. [ Conclusion] Sul2 gene was widespread in swine-derived E. coli, which was closely associated with sulfonamide resistance phenotvpes of E. coli.

Effects of dietary supplementation of probiotic,Clostridium butyricum,on growth performance,immune response,intestinal barrier function,and digestive enzyme activity in broiler chickens challenged with Escherichia coli K88

Background： Colibacillosis caused by enterotoxigenic Escherichia coil （E. coil} results in economic losses in the poultry industry. Antibiotics are usually used to control colibacillosis, however, E. coli has varying degrees of resistance to different antibiotics. Therefore the use of probiotics is becoming accepted as an alternative to antibiotics. In this study, we evaluated the effects of Clostfidium butyricum （C. butyficum） on growth performance, immune response, intestinal barrier function, and digestive enzyme activity in broiler chickens challenged with Eschefichia coli （E. coil） K88. Methods： The chickens were randomly divided into four treatment groups for 28 days. Negative control treatment （NC） consisted of birds fed a basal diet without E. coil K88 challenge and positive control treatment （PC） consisted of birds fed a basal diet and challenged with E. coil K88. C. buO/ricum probiotic treatment （CB） consisted of birds fed a diet containing 2 x 107 cfu C. buO/ricum/kg of diet and challenged with E. coil K88. Colistin sulfate antibiotic treatment （CS） consisted of birds fed a diet containing 20 mg colistin sulfate/kg of diet and challenged with E. coil K88. Results： The body weight （BW） and average day gain （ADG） in the broilers of CB group were higher （P 〈 0.05） than the broilers in the PC group overall except the ADG in the 14-21 d post-challenge. The birds in CB treatment had higher （P 〈 0.05） concentration of tumor necrosis factor-a （TNF-a） at 3 and 7 d post-challenge, and higher （P 〈 0.05） concentration of interleukin-4 （IL-4） at 14 d post-challenge than those in the PC treatment group. The concentration of serum endotoxin in CB birds was lower （P 〈 0.05） at 21 d post-challenge, and the concentrations of serum diamine oxidase in CB birds were lower （P 〈 0.05） at 14 and 21 d post-challenge than in PC birds. Birds in CB treatment group had higher （P 〈 0.05） jejunum villi height than those in PC, NC, or CS treatment at 7, 14, and 21 d post-challenge. In comparison to PC birds, the CB birds had lower （P 〈 0.05） jejunum crypt depth during the whole experiment. The birds in CB or CS treatment group had higher （P 〈 0.05） activities of amylase and protease at 3, 7, and 14 d post-challenge, and higher （P 〈 0.05） activity of lipase at 3, 7 d post-challenge than PC birds.

Antimicrobial Drug Resistance Pattern of <i>Escherichia coli</i>Isolated from Chickens Farms with Colibacillosis Infection

Colibacillosis refers to any localized or systemic infection caused entirely or partly by avian pathogenic Escherichia coli (APEC). Colibacillosis in mammals is most often a primary enteric or urinary tract disease, whereas colibacillosis in poultry is typically a localized or systemic disease occurring secondarily when host defenses have been impaired or overwhelmed by virulent E. coli strains. The purpose of this study was to investigate the antimicrobial drug resistance pattern of Escherichia coli isolated from broiler chickens farms with colibacillosis infection. Dead birds from commercial broiler chicken farms showing signs of colibacillosis were necropsied and swab samples were collected from internal organs and blood aseptically for the isolation of Escherichia coli. Pure colonies of the bacteria were isolated on solid media and the isolates were identified as E. coli based on morphological and biochemical characteristics. For determination of susceptibility to antibacterial agents, the disc diffusion method on Muller-Hinton agar was used. The following antimicrobial agents were tested: gentamycin, oxytetracyline, colistin, ciprofloxacin, doxycycline, nalidixic acid, co-trimoxazole (trimethoprim-sulfamethoxazole), norefloxacin, lincospectin and cefuroxime. The drug resistance patterns of the organisms were determined as a percentage and reported at three levels: susceptible, intermediate and resistant. All the isolates of Escherichia coli showed resistance to several antibiotics and a pattern of multiple drug resistance was observed. The highest rate of resistance was observed against nalidixic acid (100%) and the least rate of resistance was observed against gentamycin (17%). According to the results of this research care must be taken to avoid secondary infection (colibacillosis) in chicken farms and also avoid in careless antimicrobial consumption in food animals including chickens.

Antibiotic susceptibility and molecular characterization of resistance genes among Escherichia coli and among Salmonella subsp. in chicken food chains

Objective: To investigate the occurrence of resistance genes among Escherichia coli(E. coli) and Salmonella subsp. isolated in chicken food chains in Phnom Penh, 2012–2013.Methods: Six hundred eighty two E. coli and 181 Salmonella Albany, Corvallis, and Kentucky strains were examined for susceptibilities to eight antimicrobials and following resistance genes were identified by PCR: blaTem, Str A, aad A, sul1, sul2, gyr A, Tet(A), and Tet(B).Results: E. coli presented high resistances to tetracycline, amoxicillin, and sulfamethoxazole(63.1%–76.1%). Salmonella Albany and Salmonella Kentucky traduced high resistance percentages to amoxicillin, tetracycline, sulfamethoxazole, and nalidixic acid(84.6%–100%). Among amoxicillin-resistant isolates, blaTemgenes were observed for 62% of E. coli isolates and 20% of 65 Salmonella Kentucky. The Str A gene was prevalent in 36% of 331 aminoglycoside-resistant E. coli and 90% of 40 aminoglycoside-resistant Salmonella Corvallis. The sul2 gene was predominant among sulfamethoxazole-resistant isolates, for 56% of 431 E. coli and 53% of 66 Salmonella Corvallis; the sul1 gene was observed in 54% of Salmonella Albany. The Tet(A) resistance gene was prevalent in E.coli(86%), Salmonella Corvallis(82%), Salmonella Kentucky(84%). High percentages of gyr A genes observed among nalidixic-acid resistant E. coli(91%), Salmonella Albany(92%), Salmonella Corvallis(75%) and Salmonella Kentucky(85%).Conclusions: Important occurrences of resistance gene were observed among E. coli and Salmonella in chicken food chains in Cambodia.

Escherichia coli tetracycline efflux determinants in relation to tetracycline residues in chicken

Objective:To screen for Escherichia coli(E.coli)resistant to tetracycline,followed by identification of tet efflux genes by polymerase chain reaction(PCR).In addition,detection of tetracycline residues in chicken livers and kidneys were conducted using high performance liquid chromatography-tandem quadrupole mass spectrometry(HPLC-MS-MS).Methods:Strains of E.coli were isolated from samples of chicken colon and screened for tetracycline resistance.Tetracycline genes conferring resistance(Tc^r)were detected by polymerase chain reaction(PCR).Most of the isolates were resistant to tetracycline(97.9%).Results:PCR analysis indicated that Tc^r E.coli R-plasmids contained tet(A),tet(B)and a combination of both efflux genes.None of the isolates contained other efflux tet genes tet(C,D,E and Y).High performance liquid chromatography-tandem quadrupole mass spectrometry(HPLC-MS-MS),a sensitive technique,was used to detect residues of chlortetracycline(CTC),oxytetracyeline(OTC),doxveycline(DC)in chicken livers and kidneys.The samples containing tetracycline residues were at 0.13-0.65pg/μL levels.Conclusions:Tetracycline and other antibiotics are commonly used in the poultry and meat production industry for prevention of microbial infections.Multiple antibiotic resistant bacteria in Oman have increased to alarming levels,threatening public health,domestic and may have adverse effect on environment.

Prevalence of Extended Spectrum Beta-Lactamase-Producing Escherichia coli in Broiler Chickens in YaoundéCapital City of Cameroon

Background: Escherichia coli are ubiquitous bacteria colonising both humans and animals. Extended spectrum β-lactamase-producing E. coli has been selected as a suitable indicator for the monitoring and surveillance of antimicrobial resistance. Death due to resistant bacteria is continuously rising in Cameroon, but the contribution of the aviary sector is not well studied. Therefore, this study aimed to investigate the resistance profile of extended spectrum beta-lactamases-producing Escherichia coli strains, isolated from faeces of broiler chickens in Yaoundé, capital city of Cameroon. Methods: A cross-sectional descriptive study was carried out from February to June 2020. Escherichia coli were isolated from samples of broilers in poultry farms in Yaoundé and submitted to the extended spectrum β-lactamase screening. The logistic regression was used to assess the statistical association of a significance threshold p-value of 0.05. Results: Out of 385 faecal samples collected in broiler farms, 114 Escherichia coli isolates were obtained out of which 30 (26.32%) were Extended Spectrum Beta-Lactamases-producing Escherichia coli. These isolates revealed high resistance to all antibiotic families. Poor storage conditions for feeds and the proximity to latrines, the troughs on the ground, the lack of foot bath and uniforms, the inadequate treatment of faeces, the poor usage of preventive antibiotics and the lack of water treatment have been identified as risk factors to faecal carriage of ESBL-producing Escherichia coli. Conclusion: This work reveals the emergence of Extended Spectrum Beta-Lactamases-producing Escherichia coli in poultry farms in Yaoundé and the failure in the biosecurity system. As such, the awareness of poultry breeders on the respect of biosecurity measures may be an effective tool to tackle antimicrobial resistance, specifically in livestock industries using a One Health approach.

Study on Anti-infection Effect of Polysaccharide from Agaricus blazei Murrill on Chickens

In order to study the anti-bacterial infection effect of polysaccharide from Agaricus blazei Murrill on chickens, the experimental groups were orally administrated A. blazei polysaccharide at low dose and high dose, respectively, for 14 d continuously, and then, the chickens in various groups were infected with Escherichia coli or Pasteurella pneumotropica , so as to observe the clinical symptoms of chickens and record the change in body weight. Anatomy was performed 14 d later, and the organ indices were determined, so as to study the anti-bacterial infection effect of A. blazei polysaccharide on chickens. The results showed that after bacterial infection, the high-dose A. blazei polysaccharide group was significantly differed from other groups in changes of body weight and organ indices. It indicates that oral administration of high concentration of A. blazei polysaccharide could promote the development of poultry organs, thereby improving the immunity of organisms.

Environmental risk quotient of the antibiotic,phenotypic,and genotypic profiles for antibiotic resistance of Escherichia coli collected from manure and wastewater at swine farms in Prachinburi Province,Thailand

Currently,antimicrobial drug resistance is a problem that deserves thoughtful consideration.Especially in the swine production industry,many pig farms tend to release wastewater into natural water sources,which villagers use for their livelihood.This study aimed to demonstrate the occurrence of phenotypic and genotypic resistance characteristics of E.coli,as well as antibiotic residues in manure and wastewater on swine farms in Prachinburi Province,Thailand.Samples were collected in 2020 and 2021 during the rainy and summer seasons.The results of a questionnaire showed that farmers used antibiotics for disease treatment and prevention at a ratio of 2/4(50%).The most common antibiotic used was amoxicillin(4/4,100%),followed by Enrofloxacin(75%)and colistin(25%).The analysis of antibiotic residue in wastewater by Liquid Chromatography-Mass Spectrometry(LCMS,LC-MS)during the rainy season revealed that amoxicillin(54%)was the highest,followed by florfenicol(14%)and tiamulin(13%).While oxytetracycline(59%),amoxicillin(20%),and florfenicol(11%)were the highest in the summer.The study of Risk Quotient(RQ)indicated that water resources present a risk of antibiotic contamination by sulfonamides,trimethoprim,b-lactam,quinolones,and tetracycline at high levels(SRQ>1)during both seasons.The minimal inhibitory concentrations(MICs)were determined by an antibiotic susceptibility test(AST),analyzed by microdilution technique,and VITEK®2 Compact.The test result indicated that a total of 143 isolates were found in manure(45/143),pre-treatment(51/143),and final effluent(posttreatment,47/143).ESBL-positive resistance was detected at 13%.However,an immensely high percentage of antimicrobial resistance was found for ampicillin(90%),whereas imipenem did not show any drug resistance(0%).The average MIC value towards colistin in all samples was 2.71 mg/ml,while mcr1 was not found in any samples.Furthermore,MDR was expressed in E.coli at as high as 76.22%(109/143).The highest MDR pattern detected was AMP-TETeFFCeSXT.The PCR technique detected that the diversity and abundance of AMR genes were not significantly different from animal manure and wastewater at the swine farms.The bla-TEM was found more frequently than bla-PS.While the tetracycline group(tetA,tetB)and aminoglycoside(aadA1,aadA2,aadB)represented a major proportion,respectively.The PFGE study revealed the possibility of similar genetic morphology from the different isolates found in this study.

鸡大肠杆菌病研究Ⅰ．鸡E．Coli人工感染模型的建立及致病力评价

本文对分离自典型大肠杆菌病变和粪便的４５株Ｅ．Ｃｏｌｉ通过４日龄雏鸡人工感染试验建立了大肠杆菌病的人工感染模型，并对菌株的致病性进行评价。结果表明：４日龄雏鸡颈部皮下接种０．２ｍｌ菌液，接种后，前６５ｈ内雏鸡死亡率≥６０％的菌株为强致病力菌株；死亡率＜６０％，或出现典型大肠杆菌病变为中等致病力菌株；试验期不引起雏鸡死亡也无病变者为无致病力大肠杆菌。试验的１３株分离自粪便的苗株，２株为中等致病力，１１株为无致病力；３２株分离自典型病变的菌，９株为强致病力菌，１５株为中等致病力，８株为无致病力。

猪FUT2基因沉默对其所在通路基因表达及小肠上皮细胞E.coliF18黏附能力的影响

旨在细胞水平上进一步探讨FUT2基因的功能及其在猪小肠上皮细胞受到F18大肠杆菌(Escherichia coli,E.coli)侵染时的调控机制,为提高仔猪对F18大肠杆菌病抵抗力的分子选育提供理论基础。运用Real-time PCR方法检测分析FUT2基因在大肠杆菌F18ab、F18ac感染和脂多糖(LPS)诱导小肠上皮细胞前后的mRNA表达差异,并采用Western blotting方法检测大肠杆菌F18ab、F18ac感染小肠上皮细胞前后FUT2的蛋白表达差异;同时设计并构建猪FUT2基因慢病毒干扰载体,筛选并获得FUT2基因稳定沉默的小肠上皮细胞系,检测FUT2基因沉默对其所在球系列鞘糖脂生物合成通路其他关键基因(FUT1、ST3GAL1、HEXA、HEXB、B3GALNT1、NAGA)表达以及小肠上皮细胞E.coli F18黏附能力的影响。结果表明,在F18大肠杆菌感染和LPS诱导小肠上皮细胞后,FUT2基因的mRNA相对表达水平均极显著升高(P<0.01),同时大肠杆菌感染后小肠上皮细胞的FUT2蛋白表达上升。此外,本研究成功构建FUT2基因慢病毒干扰载体,并获得FUT2基因稳定沉默的小肠上皮细胞系;FUT2基因沉默后,其所在的球系列鞘糖脂生物合成通路其他关键基因的表达都存在不同程度的下降,其中FUT1基因表达水平显著下调(P<0.05),ST3GAL1、HEXA和HEXB基因表达水平极显著下调(P<0.01),而B3GALNT1和NAGA基因表达水平未发生显著变化,同时FUT2基因沉默后F18大肠杆菌对小肠上皮细胞的黏附能力显著降低。结果显示,FUT2基因低表达可能不利于仔猪大肠杆菌受体的形成,以增强猪小肠上皮细胞抵抗E.coli F18感染的能力,本试验结果同时为球系列鞘糖脂生物合成通路在仔猪抗大肠杆菌感染过程中的作用机制研究提供一定的理论基础和依据。

司帕沙星在E.coli-MG混合感染鸡的药动学与生物利用度研究

大肠杆菌-败血霉形体(Escherichia Coli.-Mycoplasma gallisepticu,E.coli-MG)疾病模型鸡单剂量(5mg.kg-1)内服和静注司帕沙星,研究其血液动力学特征和内服生物利用度。采用HPLC面积-内标法测定血浆中司帕沙星浓度,利用药动学分析软件MCPKP分析药-时数据。结果表明:疾病模型鸡内服司帕沙星血浆药-时数据符合一级吸收二室开放式模型,主要动力学参数如下:t1/2α1.7208h,t1/2β13.1773h,tm ax0.9083h,Cm ax0.6198μg.mL-1,AUC 3.8161mg.L-1.h-1。静注给药血浆中司帕沙星的经时数据符合无吸收二室开放式模型,主要动力学参数为:t1/2α0.4442h,t1/2β4.7557h,Kel0.5608h-1,Vd4.1204L.Kg-1,AUC 8.3274mg.L-1.h-1,C lB0.6004L.Kg-1.h-1。疾病模型鸡内服司帕沙星的生物利用度为47.03%。

复方中草药四味穿心莲益生菌发酵产物对鸡大肠杆菌作用

为探究复方中草药四味穿心莲益生菌发酵产物(FPSCS)对鸡大肠杆菌的作用,采用微孔-平板法测定其对O_(2)型鸡大肠杆菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),以O_(2)型鸡大肠杆菌半数致死量(LD_(50))感染SPF雏鸡制备病理模型,随机分为FPSCS高、中、低剂量组,硫酸新霉素组,四味穿心莲散组,益生菌组及对照组,统计总有效率、治愈率;ELISA试剂盒检测各组动物外周血液中炎症因子的含量。结果显示:FPSCS体外对O_(2)型鸡大肠杆菌的MIC和MBC均为31.25 mg/mL,口服FPSCS剂量为0.1~0.5 g/(次·只)的总有效率为73.33%~83.33%、治愈率为70%~80%,均显著高于四味穿心莲散组和益生菌组(P<0.05),且治疗初期可显著降低促炎因子TNF-α、IL-1β、IL-6的含量(P<0.05),显著升高IFN-γ的含量(P<0.05)。由此表明,FPSCS可通过抑杀O_(2)型鸡大肠杆菌和降低鸡外周血促炎因子的含量而发挥较好的抗菌活性。

秦皇岛地区鸡源大肠杆菌分离鉴定及药敏试验

试验旨在了解河北省秦皇岛地区养殖场鸡源大肠杆菌耐药情况,为该地区鸡大肠杆菌病的用药方案提供参考。采集秦皇岛市部分地区鸡场疑似感染大肠杆菌的病死鸡病料,采用细菌分离培养、革兰氏染色法和PCR鉴定对分离株进行鉴定,并进行药敏试验。结果显示:共检测出18株大肠杆菌,分离株对庆大霉素、丁胺卡那敏感;对哌拉西林、头孢哌酮、羧苄西林和头孢曲松呈中度耐药,耐药率为33.33%~50.00%;对青霉素、头孢他啶、苯唑西林、红霉素、头孢拉定和头孢氨苄高度耐药,耐药率为94.44%~100.00%。研究表明,应不定时检测当地鸡源大肠杆菌对常用抗生素药物的敏感性,以便及时快速地调整用药,避免造成耐药性。

2022年青岛地区鸡源和鸭源多黏菌素耐药大肠杆菌流行情况

为了分析青岛地区鸡源和鸭源多黏菌素耐药大肠杆菌的流行特征,并为多黏菌素的临床应用提供参考依据,本试验于山东省青岛市屠宰场采集鸡源和鸭源粪便样本,通过多黏菌素培养基分离大肠杆菌;分别采用琼脂稀释法、PCR、接合试验和全基因组测序,分析菌株的药物敏感性、耐药基因和毒力因子流行特征、系统发育群、mcr-1基因可转移性和遗传环境。结果显示,本试验从133份粪便样本中共分离获得26株多黏菌素耐药大肠杆菌,总分离率为19.55%(26/133),其中鸭源菌株分离率(24.24%,16/66)高于鸡源菌株(14.93%,10/67)。药物敏感性分析结果显示,所有菌株对替加环素和美罗培南全部敏感,对其余测试药物耐药率较高(42.31%~100%),所有分离菌株均存在多重耐药现象,鸡源菌株多重耐药较为分散,而鸭源菌株多重耐药集中于6和9重。26株分离菌株均携带黏菌素耐药基因mcr-1;其余耐药基因携带率介于7.69%~96.15%,tet(B)基因仅在鸡源菌株中携带(20.00%),qnrS基因在鸡源菌株中携带率(30.00%)显著低于鸭源(100%)。毒力因子检测发现,tarT、aer、pap和neuC基因在鸡源菌株中的携带率(90.00%、70.00%、50.00%和30.00%)高于鸭源(62.50%、12.50%、0%和0%)。系统发育群结果显示,青岛地区多黏菌素耐药大肠杆菌的主要系统发育群为A组,占比为76.92%。接合试验证实了部分mcr-1具有可转移性。mcr-1遗传环境结果显示,mcr-1上、下游并未发现插入序列。结果表明,mcr-1仍旧是导致禽源多黏菌素耐药大肠杆菌流行的主要“元凶”,但鸡源和鸭源多黏菌素耐药菌株在耐药性、耐药基因和毒力因子检出率等方面表现出一定差异性。因此,mcr-1在食品动物源细菌中的流行研究和监控仍旧不可忽视。

禽源大肠杆菌荧光定量PCR方法的构建及应用

为建立一种灵敏、准确且快速检测禽源大肠杆菌的方法,根据禽源大肠杆菌uidA基因的一节特异性保守序列设计引物,建立用于禽源大肠杆菌的荧光定量PCR(qPCR)检验方法,并对其各方面进行评价。试验数据表明所建立的qPCR方法的Ct值与标准品在4.69×10^(2)~4.69×10^(9 )copies/μL范围内存在优良的线性关系,线性相关系数为R2=0.993;该方法标准曲线方程为y=-3.2786x+39.032,熔解曲线表现为单峰,不存在非特异性扩增。对重组质粒标准品的最低检测浓度为4.69×10^(2) copies/μL,是普通PCR方法的1000倍。该方法检测临床样本阳性率为68.3%(41/60),普通PCR阳性检出率为23.3%(14/60),阳性检出率高出45%。此次研究建立的检测禽源大肠杆菌的荧光定量PCR检测方法可用于禽源大肠杆菌的快速诊断,对于禽大肠杆菌病的监测具有重要意义。

Dietary coated essential oil and organic acid mixture supplementation improves health of broilers infected with avian pathogenic Escherichia coli

Colibacillosis caused by avian pathogenic Escherichia coli(APEC)is a very prevalent disease in poultry farms in China.The exploration of effective non-antibiotic substances is of great significance for the control of APEC infections.This experiment evaluated the efficacy of coated essential oil and organic acid(EOA)supplementation to prevent E.coli O78 infection in broiler chickens.A total of 288 one-day-old male broiler chicks were randomly distributed into 4 groups with 6 replicates per group.Chickens were fed a diet either supplemented with EOA(500 mg/kg feed)or not,and either uninfected or infected with E.coli O78 intratracheally.Results showed that E.coli O78 infection reduced body weight gain,increased mortality and the ratio of feed to gain along with cecal and liver E.coli load,damaged gut mucosa,induced local and systemic inflammation,and altered cecal microbial composition,diversity and function(P<0.05).Supplemental EOA improved feed conversion efficiency,lowered gross lesion scores and cecal E.coli population,enhanced intestinal goblet cells and serum IgG concentration,and tended to decrease serum IL-12 production(P<0.05).Essential oil and organic acid addition downregulated IFN-γmRNA,tended to decrease mucin-2 mRNA levels while upregulating IL-10 mRNA,and tended to increase ZO-1 gene expression in the jejuna of infected birds at 7 d after E.coli O78 challenge(P<0.05).The 16S rRNA gene sequencing indicated that both EOA addition and E.coli O78 challenge altered the diversity and composition of the cecal microbiota community.Furthermore,infected birds fed EOA showed decreased Bacteroidetes and genus Lactobacillus abundance compared with the infected control.LEfSe analysis showed that Firmicutes,Ruminococcaceae,Clostridiales,Clostridia,Lactobacillus,Lactobacilaceae,and cc-115 were enriched in the non-infected but EOA-treated group(P<0.05).Collectively,dietary EOA supplementation could mildly alleviate E.coli-induced gut injury and inflammation.

MPAIV、NDV Lasota株分别与较低致病性禽源E.coli的联合感染试验

以 2× 1 0 5EID50 的低致病性禽流感病毒 ( mildly pathogenic avian influenza virus,MPAIV)、2× 1 0 6 EID50 新城疫病毒 L asota株( Newcastle disease virus Lasota strain,NDVL asota)气管内注射 1 0日龄 SPF鸡 ,2 4h后 ,同剂量、同法重复感染一次 ;48h后 ,分别气管内注射较低致病性禽病原性大肠杆菌 1 2 0( O1 8)和 1 73( O2 6 )株 ,2× 1 0 7CFU/羽 ,2 4h后同剂量、同法重复攻毒一次 ,连续观察 1 0d。结果 :MPAIV单独感染组死亡率为 53% ;NDV Lasota株单独攻毒组未见死亡 ;大肠杆菌 1 2 0株单独攻毒组死亡率为 40 % ,1 73株单独攻毒组死亡率为 7% ;MPAIV与大肠杆菌1 2 0株联合攻毒组的死亡率为 87% ,NDV L a-sota株与 1 2 0株联合攻毒组的死亡率为 40 % ;MPAIV与大肠杆菌 1 73株联合攻毒组的死亡率为 80 % ,NDV Lasota株与 1 73株联合攻毒组的死亡率为 2 0 %。

Characterization and complete genome sequence of vB_EcoP-Bp4,a novel polyvalent N4-like bacteriophage that infects chicken pathogenic Escherichia coli

Dear Editor,Pathogenic Escherichia coli cause chicken colibacillosis,which is economically devastating to the poultry industry worldwide(Bagheri et al.,2014).Owing to increasing antibiotic resistance,phage therapy reagents have been developed to treat bacterial infections(Xu et al.,2015).Coliphage N4 is the first reported phage in the'N4-like viruses'genus and the only member recognized