华北地区乳房炎奶样中大肠杆菌的耐药性研究

为了解华北地区乳房炎奶样中大肠杆菌的耐药情况,本试验采集华北地区乳房炎奶样240批次,采用EMB培养基和菌悬液法对大肠杆菌进行分离鉴定,通过纸片扩散法对常用的八类29种抗生素进行药敏试验。试验结果表明共分离大肠杆菌17株(7.08%)。药敏试验结果显示大肠杆菌分离株表现出高度耐药和多重耐药。分离株对至少4种抗生素产生耐药性,最多耐药19种,耐药5种以上的菌株较多(58.82%);针对单一抗生素,分离菌株对青霉素、苯唑西林、林可霉素3种药物耐药率高达100%。针对不同种类抗生素,大肠杆菌分离株对β-内酰胺类药物和林可酰胺类药物的耐药率分别为55.15%,61.76%,均超过半数。本研究旨在发现乳房炎奶样中大肠杆菌的耐药性规律,并根据数据对奶牛乳房炎精准防控,减少牛乳中兽药残留,提升牛乳质量。     

北京地区奶牛养殖场中大肠杆菌的分离鉴定及耐药性分析

本研究旨在调查北京某牛场牛乳房炎源大肠杆菌的耐药性,提高药物治疗效率,避免同种药物多次使用造成的耐药性,为该牛场防治大肠杆菌型的乳房炎提供数据支持和乳房炎的临床治疗提供依据。从北京某牛场采集乳样、涂抹样、粪样中分离纯化并鉴定出48株大肠杆菌,并对大肠杆菌分离的菌株进行敏感性分析。结果表明:48株大肠杆菌对24种抗菌药物中的6种药物耐药率超过50%,青霉素、苯唑西林、万古霉素的耐药率甚至达到80%以上,同一菌株最多耐药17种,最少耐药2种,耐药5种以上菌株占到72.92%。研究发现分离的大肠杆菌对多种药物产生不同程度的耐药性,存在着严重的多重耐药情况。     

新疆部分地区食源性大肠杆菌耐药性的研究

本研究对新疆乌鲁木齐、石河子、奎屯农贸市场以及超市的肉品、蔬菜、乳制品和即食食品中的大肠杆菌进行检测,从198份样品中分离出63株大肠杆菌。采用K-B法,对63株大肠杆菌进行17种抗生素敏感试验;采用PCR技术检测9种耐药基因。药敏结果表明,63株大肠杆菌对四环素(44.44%)、氨苄西林(39.68%)和萘啶酮酸(38.10%)耐药率较高,所有受试菌株对亚胺培南(0.00%)敏感性最强;肉品、蔬菜分离株对四环素(57.14%、52.94%)耐药性最强,乳源性分离株对氨苄西林(26.67%)耐药性最强,即食食品分离株对17种抗生素敏感;乌鲁木齐、奎屯、石河子分离株对四环素(65.00%、40.00%、32.14%)耐药率最高。PCR结果表明,耐药菌株中,sul2耐药基因检出率最高(75.00%),add B耐药基因的检出率最低(19.23%)。1重以上耐药菌株占总菌数的63.49%,3重以上耐药菌株占总菌数的39.68%。新疆地区食源性大肠杆菌多重耐药性比较严重。     

我国东北与西部地区乳房炎牛奶中链球菌的鉴定及耐药性比对

为了了解我国奶牛由链球菌引起的乳房炎感染现状,本论文系统地分离鉴定了我国两个地区(东北和西部)170个乳房炎乳的链球菌,并对它们进行了抗生素的耐药性比对。结果表明:我国东北和西部地区的乳房炎乳中分别分离出18株和11株链球菌;药敏试验显示,该两个地区的所有链球菌对29种抗生素药物均表现出不同程度的耐药性,其中,在东北地区链球菌中甲氧苄啶耐药菌(90.0%)、磺胺异噁唑耐药菌(80.0%)、苯唑西林耐药菌(78.5%)、林可霉素耐药菌(74.6%)、克林霉素耐药菌(66.9%)和头孢西丁耐药菌(62.3%)检出率较高;西部地区链球菌检出菌对甲氧苄啶(90.9%)、苯唑西林(81.8%)、青霉素G和磺胺异噁唑(72.7%)耐药性较高;该两个地区的乳房炎乳对抗生素都表现出多重的耐药现象。     

生鲜乳中金黄色葡萄球菌检测及性状分析

对天津市周边9家奶场原料奶中金黄色葡萄球菌污染水平、肠毒素基因的携带情况及耐药性进行调查研究。采集原料奶样品共432份,按照GB4789.10-2010对原料奶中金黄色葡萄球菌进行检验,并对筛选出来的金黄色葡萄球菌进行肠毒素基因研究、生物膜形成能力分析和耐药性分析。结果表明:采集的432份原料奶中,金黄色葡萄球菌阳性样本有14个,阳性率为3.24%,筛选出来的14株金黄色葡萄球菌携带SEA的概率为100%;14株菌中有10株分离株可以形成生物膜,其中2株可以形成中等粘附的生物膜;金黄色葡萄球菌分离株对氯霉素耐药率(100%)最高,对头孢西丁钠(21.43%)、阿米卡星(14.29%)、万古霉素(14.28%)、苯唑西林(28.57%)耐药率较高,所有菌株对环丙沙星敏感。其中有4株分离株为多重耐药株。结论:所选取的9家奶厂中,原料奶中金黄色葡萄球菌污染率相对较低,但金黄色葡萄球菌分离株肠毒素A基因检出率较高,生物膜形成能力较强,耐药情况比较严重,并且存在多重耐药和万古霉素耐药菌株,本研究为奶源性金黄色葡萄球菌的污染溯源和控制提供了相应的数据支持。     

天津地区乳房炎奶样中金黄色葡萄球菌耐药性研究

为了解天津地区奶牛乳房炎中金黄色葡萄球菌的致病情况以及对抗生素药物的敏感性,为科学治疗奶牛乳房炎提供参考以及防控兽药残留提供依据,采用甘露醇高盐培养基和冻干兔血浆对采自天津地区7个牛场50个样品进行分离鉴定,采用纸片扩散法进行药敏试验。经分离鉴定确定分离29株金黄色葡萄球菌,4株其他致病性葡萄球菌。对分离出的金葡菌进行8类29种常用抗生素的耐药性分析。对金黄色葡萄球菌分离株进行PCR扩增耐药基因,并通过琼脂糖凝胶电泳进行检测。结果表明,29株金葡菌分离株对8类29种常用抗生素均有不同程度耐药性。其中对大环内酯类、林可酰胺类药物耐药率普遍较高,平均耐药率为77.01%和89.66%,对β-内酰胺类、喹诺酮类和氨基糖苷类药物耐药率均低于50%。分离株对青霉素G、乙酰螺施霉素和林克霉素表现为完全耐药(100%),对头孢哌酮、头孢噻肟、阿莫西林、氨苄西林、恩诺沙星、新霉素和大观霉素等耐药率在20%~40%之间。分离株的耐药基因检测结果表示,耐药基因阳性检出率普遍小于耐药基因表型的检出率。     

青岛市屠宰场整鸡中沙门菌污染水平定量检测及耐药性分析

目的调查青岛市规模化肉鸡屠宰场屠宰后整鸡样品中沙门菌的污染及抗生素耐药谱分布状况。方法2014年10~12月在青岛市选择2家规模化肉鸡屠宰场,采用胴体漂洗法定量检测3次共采集的141份屠宰后整鸡样品中沙门菌,根据Kauffmann-White表对沙门菌菌株进行血清学鉴定,应用微量肉汤稀释法检测菌株对11种抗生素的耐药性。结果整鸡样品沙门菌总体污染率为74.5%(105/141),污染水平3.6~1 100 MPN/100 g,中位数为43 MPN/100 g;共分离355株沙门菌,血清型分布为肠炎沙门菌220株,印第安纳沙门菌88株和阿贡纳沙门菌19株,以及其他型28株。355株沙门菌分离株的总体耐药率为90.4%(321/355),萘啶酸(NAL)耐药率最高(88.7%,315/355)。220株肠炎沙门菌中219株(99.5%)耐药,6株(2.7%)为多重耐药株,优势耐药谱为奈啶酸(156株)。88株印第安纳沙门菌均耐药,85株为多重耐药株,优势耐药谱为庆大霉素-氯霉素-环丙沙星-萘啶酸-氨苄西林-青霉烷砜/氨苄西林-头孢他啶-头孢噻肟-复方新诺明。19株阿贡纳沙门菌除1株对奈啶酸耐药外,其余18株对所测试11种抗生素均敏感。结论青岛市肉鸡屠宰场沙门菌污染率较高,血清型以肠炎沙门菌、印第安纳沙门菌和阿贡纳沙门菌为主。沙门菌总体耐药率较高,并呈现多重耐药性趋势。     

陕西省典型冷冻食品中大肠杆菌的分子特征及耐药性检测

为了解冷冻食品中大肠杆菌污染情况,分析其潜在的食品安全问题,从陕西省4市（宝鸡、咸阳、西安和渭南）共收集冷冻食品样品360份（120份速冻水饺和240份冰淇淋）。通过选择培养和聚合酶链式反应（polymerase chain reaction,PCR）进行大肠杆菌分离鉴定。然后对分离株进行21种毒力基因、23种耐药基因、15种抗生素耐药性检测及种群分型。360份样品中大肠杆菌污染率为13.6%(49/360),其中5份样品（10.2%,5/49）大肠菌群计数超过100 CFU/g。21种被检毒力基因中有9种毒力基因被检出,以肠外致病性大肠杆菌相关基因FyuA和iss的检出率最高（均为14.3%,7/49）。药敏结果显示,菌株对β-内酰胺类抗生素和叶酸代谢抑制剂的耐药最为普遍（均为98.0%,48/49）,其次为四环素（20.4%,10/49）。其中β-内酰胺类主要编码基因为blaCTX,四环素主要编码基因为tetA。研究还发现1株分离株携带多黏菌素类抗性基因mcr-9。此外,20.4%的菌株为多重耐药菌株,最多可对13种抗生素耐药。所有分离株共有4种系统发育群（A、B1、C和F）,A群...     

酸乳用乳酸菌抗生素耐药性研究

旨在通过纸片扩散法对乳酸菌菌株耐药情况进行研究。对48份酸乳发酵剂中的乳酸菌进行分离鉴定,共分离出63株乳酸菌,其中嗜热链球菌43株、德氏乳杆菌保加利亚亚种20株。结果表明:63株乳酸菌对临床使用率较高的12种抗生素呈现不同程度的耐药性,其中,青霉素(36.51%)、复方新诺明(33.33%)、链霉素(28.57%)、氨苄西林(26.98%)、环丙沙星(20.63%),同时52.38%(33/63)的菌株具有多重耐药性,其中嗜热链球菌对12种抗生素的多重耐药性(30.23%)显著低于德氏乳杆菌保加利亚亚种(100%)。     

四川省猪肉源大肠杆菌和沙门氏菌的分离与耐药性分析

采集四川省鲜猪肉126份,选择性培养基分离大肠杆菌、沙门氏菌,划线纯化后,通过形态特性及16S rDNA序列对菌株进行鉴定,利用K-B法(CLSI)药敏试验检测大肠杆菌和沙门氏菌对17种抗生素的耐药性。结果表明：共获得大肠杆菌105株,沙门氏菌18株,检出率分别为83.33%和14.28%。大肠杆菌对各种抗生素的耐药率在0%～55.3%,对四环素、氨苄西林耐药率最高,分别为55.3%、52.3%,对其他抗菌药物的耐药率依次为卡那霉素(26.7%)＞链霉素(19.1%)＞环丙沙星(17.1%)＞诺氟沙星(14.3%)＞头孢噻吩(11.5%)＞氨苄西林/舒巴坦(4.8%)＞头孢曲松、头孢噻肟、氨曲南、庆大霉素(2.9%)＞头孢他啶(1.9%)>阿莫西林/克拉维酸(0.8%)＞丁胺卡那霉素(0.1%)＞亚胺培南、哌拉西林/他唑巴坦(0%),共产生28种耐药谱,氨苄西林、四环素及氨苄西林/四环素谱型占优势。沙门氏菌对各种抗生素的耐药率在0%～55.5%,其中对四环素、氨苄西林、链霉素的耐药率最高,依次是55.5%、38.9%、27.8%,对其他抗菌药物的耐药率依次是：氨苄西林/舒巴坦、阿莫西林/克拉维酸(11.1%)＞头孢噻肟、卡那霉素、头孢噻吩、庆大霉素、环丙沙星、诺氟沙星(5.6%)＞头孢曲松、头孢他啶、亚胺培南、氨曲南、哌拉西林/他唑巴坦、丁胺卡那霉素(0%),共产生13种耐药谱。四川省肉源大肠杆菌、沙门氏菌对各类抗生素已表现出一定的耐药性,虽耐药率相对较低,但多重耐药已经成为普遍现象,应引起足够重视,并加强对其监测。     

2019年我国不同地区牧场生牛乳中致病菌污染及抗生素耐药情况研究

目的 了解我国不同地区牧场生牛乳中致病菌污染情况和细菌耐药特征。方法 对2019年9—11月采集自43家不同地区牧场的53份生牛乳样品进行6种致病菌的分离鉴定,对分离株开展抗生素耐药性检测。结果 53份样品中大肠埃希氏菌、金黄色葡萄球菌、蜡样芽孢杆菌和单核细胞增生李斯特氏菌(单增李斯特菌)的污染率分别为62.26%(33/53)、20.75%(11/53)、5.66%(3/53)和3.77%(2/53),克罗诺杆菌和沙门氏菌均未检出。选取117株分离株进行药物敏感性实验,其中58株菌耐药,总体耐药率为49.57%(58/117);90株革兰氏阴性菌中有33株耐药,耐药率为36.67%(33/90);27株革兰氏阳性菌中有25株耐药株,耐药率为92.59%(25/17)。结论 不同地区牧场采集的生牛乳中细菌污染情况差异较大,污染随气温降低呈下降趋势。同时生乳中细菌分离株多重耐药率高,需进一步严格控制兽用抗生素的使用。     

乳品生产链金黄色葡萄球菌的污染、耐药性分析及β-内酰胺类药物耐药基因的检测

为分析乳品生产链中金黄色葡萄球菌(Sa)的污染及耐药情况,从部分乳品生产企业采集乳样(生鲜牛乳、生产车间半成品牛乳、成品牛乳)523份,按照GB 4789.10-2010及PCR方法分离鉴定Sa菌株1;采用微量肉汤稀释法,测定Sa分离株对12种抗生素的药敏性,并利用多重PCR方法分析Sa对β-内酰胺类药物耐药性的产生与其耐药相关基因(mecA、blaZ)的关联性。结果显示,乳样Sa总分离率为24.9%(129株),其中生鲜牛乳、中间半成品牛乳及成品牛乳Sa污染率分别为37.5%、7.1%和0.0%;受试Sa分离株对青霉素的耐药率(97.7%)最高,其它依次是氨苄西林(95.4%)、甲氧苄啶/磺胺甲噁唑(61.9%)、阿莫西林/克拉维酸(61.7%)、红霉素(39.7%)、四环素(36.6%)、盐酸林可霉素(35.2%);所有菌株均对苯唑西林、头孢噻呋、氟苯尼考敏感;多重耐药Sa分离率为69.8%,主要对青霉素类、磺胺类、大环类脂类、林可胺类及四环素类表现出多重耐药;多重PCR检测结果显示,129株测试Sa的nuc、blaZ、mecA阳性率分别为100.0%、60.5%及0.0%;不同生产环节乳源Sa携带blaZ基因与其对β-内酰胺类药物的耐药表型有一定的对应关系。结果表明,乳品生产链Sa污染及耐药现状已不容乐观,应引起重视,避免食源性疾病的发生。     

Prevalence,antimicrobial susceptibility,and molecular characterization of Staphylococcus aureus isolated from dairy herds in northern China

Staphylococcus aureus is one of the main pathogens involved in dairy cow mastitis. Monitoring of antibiotic use would prove useful to assess the risk of Staph. aureus in raw milk. The objective of this work was to investigate the prevalence of Staph. aureus strais isolated from raw milk in northern China, and to characterize antimicrobial susceptibility of these strains and their key virulence genes. In total, 195 raw milk samples were collected from 195 dairy farms located in 4 cities of northern China from May to September 2015. Out of 195 samples, 54 (27.7%) were positive for Staph. aureus. Among these 54 samples, 54 strains of Staph. aureus were isolated, and 16 strains were identified as methicillin-resistant Staph. aureus. The strains exhibited high percentages of resistance to penicillin G (85.2%), ampicillin (79.6%), and erythromycin (46.3%). Moreover, 72% of the strains showed resistance to more than one antimicrobial agent. Overall, 63% of penicillin-resistant strains possessed the blaZ gene, and 60% of the erythromycin-resistant strains possessed erm(A), erm(B), erm(C), msr(A), or msr(B) genes with 8 different gene patterns. All isolates resistant to gentamicin, kanamycin, and oxacillin carried the aac6'-aph2”, ant(4')-Ia, and mecA genes, respectively. Two tet(M)-positive isolates carried specific genes of the Tn916-Tn1545 transposon. The most predominant virulence genes were sec, sea, and pvl, which encode staphylococcal enterotoxins (sec and sea) and Panton-Valentine leukocidin, respectively. Thirty-two isolates (59.2%) harbored one or more virulence genes. The majority of Staph. aureus strains were multidrug resistant and carried multiple virulence genes, which may pose a risk to public health. Our data indicated that antimicrobial resistance of Staph. aureus was prevalent in dairy herds in northern China, and that antibiotics, especially penicillin G and ampicillin, to treat mastitis caused by Staph. aureus should be used with caution in northern China.     

Antibiotic Resistance Traits and Molecular Subtyping of Staphylococcus aureus Isolated from Raw Sheep Milk Cheese

The main objective of the present research was to evaluate the antibiotic resistance profiles of Staphylococcus aureus isolated from raw sheep milk cheese. A total of 150 strains were isolated from curd cheese samples and identified as S. aureus. The survey on antibiotic resistance was carried out on 47 strains, selected among isolates showing differences in the banding pattern after Pulsed Field Gel Electrophoresis (PFGE) screening or, belonging at the same pulsotype but isolated from different cheese samples. On selected strains antimicrobial resistance against ampicillin, penicillin, cloxacillin, tetracycline, erythromycin, and vancomycin was assessed by broth microdilution method. The presence of the genes coding for antibiotic resistance and virulence factors (agr alleles, sea‐see, and tst) was also investigated by PCR. Thirty‐one isolates belonging to agrI and agrIII groups carried at least one gene coding for enterotoxins or toxic shock syndrome toxin. Approximately 60% of the selected strains were susceptible to the tested antibiotics. Twelve of 47 isolates showed multiple resistance against ampicillin and penicillin. Only 1 strain, represented by a unique PFGE profile showed simultaneous resistance to ampicillin, penicillin and cloxacillin. Single resistance against tetracycline was found in 5 isolates belonging to 2 different pulsotypes. The results of this study suggest that the recovery of S. aureus resistant strains in raw milk cheese samples is quite common but it is limited to few antibiotic classes, mainly β‐lactams and tetracyclines. None of the strains showed resistance to erythromycin and vancomycin.     

Occurrence and characterization of Escherichia coli O157 and other serotypes in raw meat products in Morocco

In this study, 100 raw meat samples were collected from 15 local Moroccan butcheries in five different areas of the city of Rabat during a period of 4 months. Overall, 7 of 15 butcheries from three areas of the city yielded strains of Escherichia coli O157. Single isolates from 9 (9%) of 100 raw meat samples were biochemically and serologically confirmed as E. coli O157. Using molecular techniques, two strains were positive for the Shiga toxin, with two additional strains containing an attaching-effacing gene. All potentially virulent serotypes isolated from these meat samples showed distinct pulsed-field gel electrophoresis profiles. Based on antibiotic susceptibility testing, more than 70% of the isolates were resistant to ampicillin and clavulanic acid-amoxicillin. Moreover, one strain was resistant to more than three antibiotics. Our study represents the first survey of E. coli O157 and related serotypes in raw meat products in Morocco.     

奶牛场采奶环节大肠埃希氏菌分离鉴定及对抗生素和消毒剂的抗性分析

为了解奶牛场采奶过程中大肠埃希氏菌污染状况、菌株所携带毒力基因及其对抗生素和消毒剂抗性.选择成都市某奶牛场随机采集655份样品,对致病性大肠埃希氏菌进行分离鉴定,并检测分离株携带的毒力基因、耐药基因以及抗消毒剂基因,筛选出毒力强菌株,分别检测菌株对抗生素和消毒剂的敏感性.结果 表明,一共分离得到249株大肠埃希氏菌,鉴...     

Enterococcus faecalis and Enterococcus faecium isolates from milk,beef, and chicken and their antibiotic resistance

The occurrence and antibiotic resistance of enterococci, especially Enterococcus faecalis and Enterococcus faecium, in milk, beef, and chicken in Gaborone, Botswana, were studied. Enterococci were isolated from these sources with the use of bile esculin agar and identified with API 20 Strep kits. Antibiotic resistance was determined by the disk diffusion method. The antibiotics tested were vancomycin, teicoplanin, ampicillin, tetracycline, and cephalothin. Among the 1,467 enterococci isolated from the samples, E. faecalis (46.1%) and E. faecium (29.0%) were found to be the predominant species. Other enterococcal species made up 25% of the isolates. More than 96 and 97% of the E. faecalis and E. faecium isolates, respectively, were found to be resistant to ampicillin. Almost 34, 27.3, and 22.4% of the E. faecalis isolates from milk, beef, and chicken, respectively, were also resistant to cephalothin. The percentages of E. faecium isolates that were found to be resistant to cephalothin were 32.8, 16.9, and 17.3% for milk, beef, and chicken, respectively. Resistance to vancomycin was widespread. It was found that 18.8, 7.8. and 13.1% of the E. faecalis isolates from milk, beef, and chicken samples, respectively, were resistant to vancomycin. In contrast, 32.8, 24.7, and 30.7% of the E. faecium isolates from milk, beef, and chicken samples, respectively, were resistant to vancomycin. Isolates that were resistant to multiple drugs were found in relatively large numbers.     

羊奶粉生产中金黄色葡萄球菌分离鉴定及其分子特性和耐药性检测

为探究羊奶粉在加工过程中金黄色葡萄球菌污染的关键环节及菌株的分子特征和耐药性,对某羊奶粉加工厂不同生产环节进行样本收集,通过采用选择培养和聚合酶链式反应扩增nuc基因对金黄色葡萄球菌进行分离鉴定,然后对分离的菌株进行毒素基因（21 种）、耐药性（16 种常用抗生素）及葡萄球菌A蛋白（staphylococcal protein A,SPA）、多位点序列分型（multilocus sequence typing,MLST）和脉冲场凝胶电泳（pulsed field gel electrophpresis,PFGE）分型研究。结果表明,收集的112 份样本中有6 份样本被污染（5.4%,6/112）,其中包括加工设备（2 份）、加工人员（2 份）、罐奶（1 份）和车间落地粉（1 份）。所有的分离株至少携带1 种毒素基因,其中以pvl基因的携带率最高（100.0%,6/6）,其次为sea、sec、see、seh、sek和seq（50.0%,3/6）,seg、sej和ser（33.3%,2/6）,sed、sei、sem和seo（16.7%,1/6）。所有分离株至少耐受4 种抗生素,其中对氨苄西林、头孢哌酮、甲氧苄啶/磺胺甲恶唑和青霉素的耐药性最为普遍（100.0%,6/6）,其次为红霉素和阿莫西林/克拉维酸（83.3%,5/6）、四环素（50.0%,3/6）和庆大霉素（16.7%,1/6）。此外,所有菌株对苯唑西林、头孢西丁、万古霉素、利奈唑胺等抗生素敏感。所有分离株共有4 种spa分型和3 种ST分型,其中以ST1-t127（50.0%,3/6）为主,其次为ST5-t002、ST5-t548和ST188-t189（16.7%,1/6）。对于PFGE分型,可分为3 个大簇（I、II和III簇）和4 个基因型（A、B、C和D）,其中加工设备和落地粉存在相同的PFGE分型。研究结果表明在羊奶粉加工过程中存在金黄色葡萄球菌污染现象,罐奶、加工设备、加工人员和落地粉是受污染的关键环节,且在不同的加工环节中存在一定的交叉污染。虽然污染率较低,有必要对奶厂不同加工环节的污染情况进行长期调查,确认关键污染环节,可以有效控制金黄色葡萄球菌在奶粉制品中的扩散。