中圖分類號:S855 文獻標志碼:A 文章編號:1001-4330(2025)04-1022-10
0 引言
【研究意義】金黃色葡萄球菌(Staphylococcusaureus,S.aureus)是一種常見的革蘭氏陽性菌,可導致多種禽類疾病,如傳染性關(guān)節(jié)炎、漿液性滑膜炎和葡萄球菌性敗血癥等[1]。并且,其可在動物體內(nèi)定植,鵝感染金黃色葡萄球菌后往往無明顯癥狀,但會污染鵝肉、鵝蛋等[2],引起食物中毒[3]。因此,加強對屠宰環(huán)節(jié)中金黃色葡萄球菌耐藥性的監(jiān)測有對預防及控制食源性疾病有實際意義?!厩叭搜芯窟M展】金黃色葡萄球菌能分泌出一種或多種細胞外蛋白,如溶血素、殺白細胞素、腸毒素、毒素休克綜合征毒素等,這些蛋白可引發(fā)多種疾病[4]。其中,由傳統(tǒng)腸毒素 (sea~see) (20引起暴發(fā)的金黃色葡萄球菌相關(guān)的食物中毒事件超過了 90% [5]。有研究顯示,金黃色葡萄球菌所致的食物中毒占 20%~25%[6] 。對食品進行高溫加熱時,能夠殺滅病原微生物,但是像金黃色葡萄球菌這樣的細菌,其所產(chǎn)生的腸毒素經(jīng)高溫加熱后仍具有一定的生物活性[7]。分子分型包括多位點序列分型(multilocussequence typing,MLST)和腸桿菌科基因間重復序列PCR分型(enterobac-terial repetitive intergenic consensus-PCR,ERIC-PCR)、葡萄球菌蛋白A分型(staphylococcalproteinA,SPA)等,廣泛應用于分離菌株的遺傳多樣性和菌株間的關(guān)系。其中SPA分型針對金黃色葡萄球菌分離株具有較高的鑒別能力,且分型準確、速度快、可重復性和易于解釋[8]。研究表明,新疆食源性疾病的爆發(fā)多由金黃色葡萄球菌引起[9]?!颈狙芯壳腥朦c】加強對鵝屠宰環(huán)節(jié)中金黃色葡萄球菌耐藥性的監(jiān)測尤為重要。因此,需研究對新疆鵝屠宰加工環(huán)節(jié)中金黃色葡萄球菌的分子特征及耐藥情況?!緮M解決的關(guān)鍵問題】分析新疆南疆某鵝屠宰場不同屠宰環(huán)節(jié)中金黃色葡萄球菌的污染程度,研究分離菌株的耐藥特征、毒力基因和SPA分型特征,為金黃色葡萄球菌的防控、保障鵝肉產(chǎn)品安全提供科學依據(jù)。
1 材料與方法
1.1 材料
1. 1.1 樣品和采集
于2021年6\~8月采集新疆某鵝屠宰場不同屠宰環(huán)節(jié)樣本。共收集樣本153份,包括刀具拭子(D)10份、工人手部拭子(G)25份、生產(chǎn)器具/案板拭子(S)35份、褪毛后鵝胴體拭子(T)28份和鵝胸脯肉樣(R)28份。將收集的鵝肉、拭子樣本分別置于無菌采樣袋 ,5mL 無菌離心管,記錄相關(guān)信息后,低溫運至實驗室,其間隔不超過12h。
1. 1.2 儀器與試劑
恒溫培養(yǎng)箱(DHP-9162)上海一恒科學儀器有限公司;立式壓力蒸汽高壓鍋(LDZX-50KB)上海申安醫(yī)療器械廠;博迅凈化工作臺(SW-CJ-2FD)上海博迅實業(yè)有限公司;PCR儀(C100TOUCH)金壇市醫(yī)療器械廠;水平電泳槽(DYCP-31 DN)北京六一生物科技有限公司;高速離心機(SCILOGEX)和凝膠成像系統(tǒng)(GELDOCXR)美國BIO-RAD公司。
7.5% 氯化鈉肉湯、Baird-Parker(BP)瓊脂、Mueller-Hinton(MH)瓊脂、金黃色葡萄球菌顯色培養(yǎng)基和亞碲酸鹽卵黃增菌液均購于海博生物技術(shù)有限公司。核酸染料、瓊脂糖和 50×TAE 均購于北京鼎國昌盛生物技術(shù)有限責任公司。 2×Taq MasterMix ddH2O 、DNAMaker均購于Takara寶日醫(yī)生物技術(shù)有限公司。12種抗菌藥物恩諾沙星(Enrofloxacin,ENR)、卡那霉素(Kanamycin,KAN)、氯霉素(Chloramphenicol,CHL)、頭孢噻呋(Ceftiofur,CF)阿奇霉素(Azithromycin,AZM)、頭孢西丁鈉(CefoxitinSodium,F(xiàn)OX)、慶大霉素(Gentamicin,GEN)、阿莫西林/克拉維酸鉀(Amoxicillin/clavulanateacid,AMC)、環(huán)丙沙星(Ciprofloxacin,CIP)、萬古霉素(Vancomycin,VAN)、磺胺異惡唑(Sulfisoxazole,SIZ)氨芐西林(Ampicillin,AMP)全部購自中國獸醫(yī)藥品監(jiān)察所。
1.2 方法
1. 2. 1 金黃色葡萄球菌的分離與鑒定
參照《食品安全國家標準食品微生物學檢驗金黃色葡萄球菌檢驗》 GB 4789.10-2016[10] 對金黃色葡萄球菌進行分離與培養(yǎng)。用水煮法提取細菌DNA,進行金黃色葡萄球菌特異性基因nuc的擴增[11]。將陽性菌株于 -20% 冰箱保存?zhèn)溆?。?
1.2.2 SPA分型
參考文獻[12]合成 SPA引物。PCR反應條件: 95°C 預變性 5min;95°C 變性45s, 60°C 退火45s, 72% 延伸 90s ,共30個循環(huán); 72% 再延伸10min后保存于 16°C 。將擴增產(chǎn)物送至北京擎科生物科技股份有限公司西安分公司測序,測序結(jié)果在 CDC spa 分型網(wǎng)站 https://cge.cbs.dtu. dk/services/spatyper/進行分析。
1.2.3金黃色葡萄球菌的毒力基因檢測
參考Varshney AK[11] 文獻中經(jīng)典腸毒素(sea、seb、sec、sed、see)和新型腸毒素(seg、seh、sel、sei、sek、sem和 seu )的引物序列,于西安擎科新業(yè)生物技術(shù)有限公司合成。PCR擴增反應體系為25μL ,其中 2× Taq Master Mix 13μL,ddH2O; 0μL ,上下游引物各 1μL ,DNA模板 2μL PCR產(chǎn)物于 1% 凝膠中電泳,在凝膠成像系統(tǒng)進行結(jié)果判定。
1.2.4金黃色葡萄球菌的耐藥性調(diào)查
參考CLSI標準[13],使用瓊脂稀釋法對金黃色葡萄球菌進行12種抗生素的耐藥性調(diào)查,將金黃色葡萄球菌ATCC29213和大腸桿菌ATCC25922作為藥敏試驗的質(zhì)控菌株,瓊脂稀釋法具體操作步驟參考邵莉萍等[14]方法。判定結(jié)果為敏感(S)、中介(I)和耐藥(R)3種標準。分離株藥敏結(jié)果根據(jù)CLSI標準判定。表2
表1 所用引物
1.3 數(shù)據(jù)處理
利用Minitab?16.2.3對試驗數(shù)據(jù)進行處理,采用 χ2 檢驗對不同環(huán)節(jié)金黃色葡萄球菌檢出率進行差異分析, Plt;0.05 ,差異顯著。
2 結(jié)果與分析
2.1 金黃色葡萄球菌的檢出情況
研究表明,對屠宰場收集的153個樣本進行選擇性培養(yǎng)及 nuc 基因鑒定,共有49份樣品中存在金黃色葡萄球菌,分離率為 32.0% (49/153)。各個屠宰環(huán)節(jié)均有金黃色葡萄球菌檢出,其中鵝胴體拭子樣品, (40.0% )分離率最高,其次為生產(chǎn)器具拭子樣品( 34.3% )、工人手部拭子樣品( 36.0% )鵝肉樣品( 14.3% )和刀具拭子樣品! 20.0% )。不同屠宰環(huán)節(jié)中均檢出金黃色葡萄球菌,盡管各環(huán)節(jié)檢出的樣本數(shù)、檢出率不同,但金黃色葡萄球菌陽性樣本檢出率無顯著差異( P gt;0.05 )。表3
表3 不同屠宰環(huán)節(jié)中金黃色葡萄球菌的流行情況
2.2 金黃色葡萄球菌的分子分型
研究表明,對49株分離株進行SPA分型,分型結(jié)果包括7種SPA分型和3種未知分型。對于SPA分型,主要分子型為t078( 36.7% ,18/49),其次為t034( 30.6% , 15/49 ) .1502(16.3%,8/49) ,t701 ( 4.1% ,2/49),t1376、t002和 t091( 2.0% , 49)。同一屠宰加工環(huán)節(jié)中金黃色葡萄球菌分離株具有多種分型。t034分型的金黃色葡萄球菌普遍具有四重( 33.3% )和五重(33.3)耐藥性,但是腸毒素基因攜帶較低;
分型的金黃色葡萄球菌多以三重( 44.4% )和四重( 33.3% )耐藥為主,并且腸毒素基因攜帶率也較高;t502分型的金黃色葡萄球菌雖耐藥情況比t034和t078差,但其腸毒素基因攜帶率較高; 1034,11376,1002 和t091及未知分型的腸毒素基因攜帶率均較低。表4
2.3 毒力基因檢測結(jié)果
研究表明,對鑒定的49株金黃色葡萄球菌進行12種腸毒素基因的檢測,有26株金黃色葡萄球菌編碼了腸毒素基因,檢出率為 53.1% ,5種腸毒素編碼基因 sec,sed…see,sel,sek 未被檢出。其中經(jīng)典腸毒素sea和seb的檢出率分別為 2.0% ( 49)和 26.5% (13/49),新型腸毒素 seg,seh,sei 、sem和seu的檢出率分別是 46.9% (23/49)2.0% ( 1/49 ) 32.7% ( 16/49 ) ,24.5% (12/49)、28.6% (14/49),其中經(jīng)典腸毒素以 seb 為主,新型腸毒素以 seg,sei,sem 和 seu 為主。共有14種毒素編碼基因譜,其中頻繁檢出的腸毒素基因譜為 seg-sei-sem-seu(8.2%,4/49)?. seg-sei -sem - seu ( 6.1% ,3/49)和
(6.1%,3/49 )。表5
Tab.4 Summary of SPA typing,virulence gene profiles and antimicrobial resistance profiles of 49S.aureus isolates
2.4 金黃色葡萄球菌的耐藥性結(jié)果
研究表明,有 93.9% 金黃色葡萄球菌對所測抗生素表現(xiàn)出耐藥,所測抗生素耐藥率從高到低依次是氨芐西林 73.5% 、阿奇霉素 67.3% 、磺胺異惡唑哦 61.2% 、環(huán)丙沙星 49.0% 、氯霉素16.3% 、恩諾沙星 14.3% 萬古霉素 10.2% 、頭孢西丁鈉 6.1% 、卡那霉素 4.1% 、頭孢噻呋 2.0% 。對慶大霉素和阿莫西林克拉維酸鉀不耐藥。此外,46株金黃色葡萄球菌共有21種耐藥譜,有31株是多重耐藥菌,占分離菌株的 63.3% ,還存在6重耐藥和7重耐藥菌。其中,最常檢出的耐藥譜為 AZM-CIP-SIZ-AMP(16.3%,8/49) ,其次為 AZM-SIZ-AMP(14.3%,7/49 )、AZM-AMP( 10.2% ,5/49)和 ENR-AZM-CIP-SIZ-AMP (6.1%,3/49 )。不同屠宰加工環(huán)節(jié)均存在多重耐藥菌株,其中鵝胴體拭子、刀具拭子及工人手部拭子金黃色葡萄球菌分離株耐藥最為嚴重。表6
3討論
3.1金黃色葡萄球菌是全世界范圍內(nèi)危害人類健康和影響經(jīng)濟發(fā)展的三大食源性致病菌之」[15],在各類食品中均檢出過金黃色葡萄球菌,其中肉類和乳制品的檢出率較高。有研究表明,屠宰加工環(huán)節(jié)中工人手部、刀具以及生產(chǎn)器具與胴體表面接觸,從而導致胴體污染[16]。Vossenku-hl等[17]報道,火雞產(chǎn)業(yè)鏈中屠宰場胴體拭子金黃色葡萄球菌的檢出率最高( 65.5% ),與研究中鵝胴體檢出率最高( 40.0% )一致。此外,研究中工人手部拭子樣本( 36.0% )和生產(chǎn)器具/案板拭子樣本 (34.3% )金黃色葡萄球菌污染情況僅次于鵝胴體拭子樣本。王琳等的研究也表明了此現(xiàn)象。因此,對于跟鵝胴體直接接觸的生產(chǎn)器具應定時消毒。生產(chǎn)器具邊角易留下污垢,如不及時清理會隨著時間的延長加速細菌的增長繁殖。3.2研究鵝源金黃色葡萄球菌的SPA分型以t078和t034、t502為主,其中t078和t502的腸毒素基因攜帶率較高。而Yan等[19]的報道表明,引起中國深圳食物中毒的金黃色葡萄球菌,其優(yōu)勢分子型是ST7-t091,普遍攜帶sea 基因。Li等[20]對 2006~2013 年間金黃色葡萄球菌分離株進行了分子流行病學調(diào)查,結(jié)果表明t701(71.4% )為優(yōu)勢型,其次為 1002(14.3% )和t1720 14.3% )。Liao等[2]的研究發(fā)現(xiàn),t701( 15% )、t091( 13% )和t002( 10% )分型為中國西南地區(qū)食品中金黃色葡萄球菌分離株的主要類型。而研究中分離菌株只存在少量的SPA分型t002、t091和t701,表明不同地區(qū)之間食物源金黃色葡萄球菌分型存在差異。
引起金黃色葡萄球菌食物中毒(Staphylococ-calfoodpoisoning,SFP)的主要原因是其產(chǎn)生了致病性的腸毒素,該毒素耐熱,不易被破壞。49株金黃色葡萄球菌中有26株編碼了腸毒素基因,經(jīng)典腸毒素以seb為主( 26.5% );新型腸毒素主要為 seg,sei,sem 和 seu ,檢出率分別為 46.9% 、32.7%.24.5% 和 28.6% 。李方等[22]報道食品中金黃色葡萄球菌經(jīng)典腸毒素以sea為主(54.0% )。任強[23]檢測奶牛乳源金黃色葡萄球菌的經(jīng)典腸毒素以sec和sed為主( 24.3% 和41.1% ),新型腸毒素以seh和sei為主( 25.2% 和57.0% )。張鵬飛等[24報道檢測肉雞屠宰環(huán)節(jié)中96.9% 的金黃色葡萄球菌菌株攜帶新型腸毒素編碼基因,同時有 18.8% 的金黃色葡萄球菌菌株攜帶經(jīng)典腸毒素 seb 。也有報道雞肉中金黃色葡萄球菌菌株攜帶經(jīng)典腸毒素以seb 為主[。雖然經(jīng)典腸毒素是引發(fā)SFP的主要原因,而有文獻報道引發(fā)食物中毒的金黃色葡萄球菌不攜帶經(jīng)典腸毒素,攜帶6種新型腸毒素 (seg,sei,sem,sen,seo 和seu)[25]。試驗研究中 seb(26.5% ) ,seg(46.9% )S i(32.7% ) ,sem(24.5%) 及 seu(28.6% 腸毒素基因被檢出。
3.3Sallam等[26]對零售雞耐甲氧西林金黃色葡萄球菌的耐藥性分析顯示,分離的MRSA菌株對多個抗生素耐藥。Igbinosa等27的研究表明,零售禽肉中耐甲氧西林金黃色葡萄球菌具有多重耐藥性 (80.9% )。 Wu 等[28]報道零售肉制品中金黃色葡萄球菌的多重耐藥率高達 94.6% 。研究調(diào)查中金黃色葡萄球菌主要對氨芐西林1 73.5% )、阿奇霉素( 67.3% )、磺胺異惡唑(61.2% )和環(huán)丙沙星 (49.0%) 等耐藥[29]。在Ning 等[30]對生奶中金黃色葡萄球菌分離株的耐藥性研究發(fā)現(xiàn),菌株對慶大霉素( 19.73% )、阿莫西林/克拉維酸鉀( 3.95% )以及恩諾沙星(3.95% )的耐藥率較低。此外,研究樣本中63.3% 的金黃色葡萄球菌菌株具有多重耐藥性,高于Lin等[31]對散裝即食食品中金黃色葡萄球菌的多重耐藥率 (38.9% )。研究結(jié)果顯示,不同屠宰加工環(huán)節(jié)分離株存在相同分子分型,但是不同環(huán)節(jié)的耐藥譜和毒力基因攜帶情況各不相同。
4結(jié)論
對新疆南疆某鵝屠宰場屠宰環(huán)節(jié)中金黃色葡萄球菌腸毒素基因和耐藥性及SPA分型進行研究,某鵝屠宰場金黃色葡萄球菌污染,其中鵝胴體污染率最高,分離株主要為t078和t034、t502分型,分離的金黃色葡萄球菌攜帶多種腸毒素,并且63.3% 的分離株表現(xiàn)出多重耐藥。
參考文獻(References)
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Abstract:【Objective】 To investigate the presence of Staphylococcus aureus contamination in a geese slaughterhouse located in southern Xinjiang by analyzing the virulence genes,antibiotic resistance,and typing of the isolated strains.The investigation results of pollution in diffrent links are helpful to analyze the key control points of pollution in slaughtering and processing links,andcan effectively prevent andcontrol the outbreak of foodborne diseases.【Methods】A total of 153 samples (including swabs and meat samples taken from knives,workers'hands,production equipment,goose carcasses)were collcted in the goose slaughterhouse. The isolation and identification of Staphylococcus aureus wereachieved by combining traditional culture methods with PCR technology.Simultaneously,12 enterotoxin genes were identified,along with the detection of staphylococcal protein A.The resistance of 12 types of antibiotics was investigated using the AGAR dilution method.【Results】From this goose abattoir,a total of 49 strains of S .aureus were isolated and identified,resulting in an isolation rate of 32.0% . The highest isolation rate of 40.0% (22/55) was found in goose carcasses, followed by 36.0% (9/25)in workers hands, 34.3% (12/35) in production utensils, 20.0% (2/ 10)in knives,and 14.3% (4/28)in goose meat.All isolates consisted of seven clonotypes(tO78,t034, t502,t701,tl376,tOO2,and t091)and three unidentified subtypes. Seven enterotoxin genes were identified,with seb ( 26.5% ),seg ( 46.9% ),sei (32.7% ),sem( 24.5% ),and seu (28.6% )genes being commonly discovered. The drug sensitivity results revealed that 49 strains of S . aureus exhibited multi - drug resistance,with resistance rates to ampicillin,azithromycin,sulfisoxazole,and ciprofloxacin ranging from 73. (204 50% to 49.0% . The multi -drug resistance was mainly triple and quadruple resistance,and the highest was seven-fold resistance.【Conclusion】 Staphylococcus aureus is seriously contaminated in goose slaughterhouses,and cross-contamination occurs in different processing links.The contamination rate of goose carcasses is the highest,which accounts for 40.0% . The isolates are mainly classified as tO78,tO34 and t5O2.Staphylococcus aureus isolates carries a variety of enterotoxins,and 63.3% of isolates show multiple drug resistance.
Key words :goose; slaughtering and processing chain; Staphylococcus aureus; molecular characteristics;drug resistance