首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献，搜索用时 281 毫秒
1.
东北地区猪链球菌对大环内酯类药物耐药机制的研究   总被引：1，自引：0，他引：1  
采用微量稀释法及双纸片扩散法测定了28株猪链球菌（S．suis）对大环内酯类药物的耐药性和耐药表型，红霉素、阿奇霉素和泰乐菌素耐药率分别为92．8％、92.8％和89.3％，耐药表型以内在型（cMLSB）为主。利用聚合酶链反应（PCR）检测红霉素耐药基因erm和mef,对ermA／B／C分型扩增、克隆、测序，26株菌扩增到ermB基因，16株菌扩增到ermA基因，其中15株同时扩增到ermB和ermA基因，1株未扩增到这两种基因的任一种；28株猪链球菌中均未扩增到ermC和mef基因。16株菌的c17nA基因核苷酸序列与GenBank中同源序列同源性为83％～100％，氨基酸序列与参照序列（X03216，1）相比突变点较多，有11株菌在34个位点处同时发生了改变；26株菌的ermB基因核苷酸序列与GenBank中同源序列相似性为98％～100％，氨基酸序列与参照序列（AY183117．1）相比突变点较少，与参照序列完全一致的有7株，其余株仅1～3个氨基酸不同。说明本地区猪链球菌对大环内酯类药物耐药情况很严重，耐药基因为甲基化酶ermA和／或ermB，ermA基因突变点较多，ermB基因相对稳定。  相似文献   

2.
采用微量肉汤稀释法和D-试验法检测64株凝固酶阴性葡萄球菌（CNs）对10种抗菌药物的耐药性,并用PCR方法分别检测头孢西丁耐药菌株和红霉素耐药菌株中mecA基因以及erinA、ermB、ermC和msrA基因的携带情况。结果表明,所有菌株均对万古霉素和甲氧苄啶／磺胺甲恶唑敏感;泰妙菌素为耐药率（65．6％）最高的抗菌药物,其次是红霉素、氧氟沙星和β-内酰胺类药物。28株（43．8％）CNS对青霉素耐药,其中26株对头孢西丁耐药（MRS）并且均携带mecA基因。30株（46．9％）CNS对红霉素耐药,其中24株为MLSB耐药表型,主要由ermB基因介导。总之,兽医临床CNs分离株对常用抗菌药物的耐药性不同,mecA基因和ermB基因的携带分别是兽医临床MRS和MLSB表型产生的主要原因。  相似文献   

3.
红霉素与四环素耐药基因在猪链球菌临床分离株中的检测   总被引：1，自引：1，他引：0  
为了解临床分离的48株猪链球菌对大环内酯类药物及四环素耐药基因的分布,用微量稀释法测定48株临床分离的猪链球菌对大环内酯类、四环素、β-内酰胺类及头孢类9种抗生素的药物敏感性,建立PCR方法对耐药菌株大环内酯类耐药基因ermA/B/C、mefA/E、msrD、mphB、23S rRNA,L4,L22和四环素耐药基因tetM、tetO、tetL、tetK及与Tn916转座子相关的int和xis基因进行检测。结果表明,31株2型猪链球菌中大环内酯类药物耐药率为3.23%,17株9型猪链球菌红霉素耐药率为88.24%,泰乐菌素、磷酸替米考星、阿奇霉素的耐药率均为70.59%。48株猪链球菌对四环素均耐药,但对青霉素、阿莫西林、头孢曲松钠、氨苄西林均敏感。大环内酯类耐药基因主要以ermB为主,占75%(12/16),mefA/E、msrD占25%(4/16),16株红霉素耐药菌株中,tetM、tetO、int、xis的检出率分别为25%(4/16)、62.5%(10/16)、31.25%(5/16)和31.25%(5/16),没有检测到ermA、ermC、mphB、tetL、tetK。所有红霉素耐药菌株均未检测到23S rRNA、L4和L22突变。  相似文献   

4.
鸡毒支原体（Mycoplasma gallisepticum，MG）是禽类主要病原菌之一，其感染引起鸡慢性呼吸道病（CRD）和火鸡传染性窦炎。目前预防鸡毒支原体感染仍主要依靠抗菌药物，但长期广泛应用抗菌药物造成鸡毒支原体耐药性不断发展。有调查表明，鸡毒支原体临床株对四环素类、大环内酯类及氟喹诺酮类等抗菌药物已产生了耐药性，造成药物疗效下降甚至失效。由于支原体分离培养困难，国内外对动物源支原体耐药性研究十分有限，至今未见有鸡毒支原体大环内酯类抗生素耐药机制的研究报道。本文以鸡毒支原体S6株为模式菌，研究红霉素和替米考星在体外诱导鸡毒支原体的耐药情况，并分析耐药菌株23S rRNA基因V域的耐药突变特征。  相似文献   

5.
猪链球菌(Streptococcus suis,SS)是危害世界养猪业的重要细菌性病原菌之一,本研究旨在了解猪链球菌临床分离株的耐药性特点和四环素耐药基因的携带情况,为临床上该病的防控提供科学依据。本试验采用K-B法和CLSI推荐的肉汤微量稀释法检测猪链球菌广东分离株对18种抗菌药物的耐药性。结果显示,被检菌株对四环素类、磺胺类和氨基糖苷类抗菌药物表现较强的耐药性,尤其对四环素类药物的耐药率高达98.2%;对头孢菌素类药物比较敏感;菌株都耐受6种或6种以上的抗菌药物,其中以6和14重耐药菌株的数量最多,分别占20%和17%。本试验设计了4对引物检测四环素耐药基因携带情况,结果发现56株菌中以携带tetM基因为最多(85.71%)。结果表明tetM很可能是介导广东SS分离株对四环素产生极高耐药率的主要原因之一。  相似文献   

6.
为了解莆田市番鸭源鸭疫里默氏菌对大环内酯类药物的耐药性和相关耐药基因携带情况,对本实验室分离鉴定的49株番鸭源鸭疫里默氏菌菌株采用K-B纸片扩散法进行药敏试验,提取菌株基因组DNA,采用PCR方法对大环内酯类药物的ermA、ermB、ermC、ermF、ereD等5种耐药基因进行检测,阳性产物送公司测序并对序列进行分析...  相似文献   

7.
为调查上海市猪链球菌耐药情况,采用体外最小抑菌浓度(MIC)药物敏感试验,对2004—2017年从上海市分离的150株猪链球菌,开展了5类8种临床常见抗菌药物的敏感性检测。结果显示:95%的猪链球菌对8种抗菌药物产生了不同程度的耐药,耐药率为16.67%~90.00%。对β-内酰胺类药物的耐药性较低,耐药率分别为氨苄西林16.67%、青霉素19.33%、头孢噻呋26.00%,但也表现出耐药性加重的趋势;对酰胺醇类和喹诺酮类药物出现了一定程度的耐药,其中对氟苯尼考的耐药率为24.67%,对环丙沙星和氧氟沙星的耐药率均为42.00%;对大环内酯类和四环素类药物则出现了极高的耐药性,其中对红霉素、四环素的耐药率分别达到82.67%、90.00%。46%的菌株为多重耐药,其中10.7%的菌株为8重耐药。结果表明,上海市猪链球菌耐药情况较为严峻,除对β-内酰胺类药物较为敏感外,对其他药物均出现了不同程度的耐药,且普遍为多重耐药。因此,上海市需加强兽用抗菌药物的临床用药指导,倡导合理规范用药。  相似文献   

8.
对广西规模化猪场分离的120株猪源大肠杆菌进行了头孢菌素类、氟喹诺酮类、氨基糖苷类、四环素类、大环内酯类和酰胺醇类药物耐药表型检测,并通过PCR检测菌株的β-内酰胺酶基因(bla_(TEM)、bla_(CTX-M))、氟喹诺酮类耐药基因(qnrA、oqxA、oqxB)、氨基糖苷类耐药基因(aac(6′)-Ib-cr)、大环内酯类耐药基因(ermB)和酰胺醇类耐药基因(floR)携带情况。耐药性检测结果显示,猪源大肠杆菌对头孢西丁、头孢他啶和阿米卡星具有高敏感率(74.0%),而耐药率最高为四环素类84.2%,酰胺醇类为70.8%,氟喹诺酮类为68.9%,氨基糖苷类为49.4%,大环内酯类为43.3%,最低为头孢菌素类31.4%。猪源大肠杆菌最低对1种药物耐药,最高对18种药物耐药,111株为多重耐药菌,以11耐(15株)、8耐(13株)和7耐(12株)为主,共有82种耐药谱型。耐药基因检测结果显示,8个耐药基因的阳性率均≥50.0%,其中阳性率最高为bla_(TEM)基因(91.7%),最低为aac(6′)-Ib-cr基因(50.0%),共存在53种基因组合类型,主要为bla_(TEM)+bla_(CTX-M)+qnrA+oqxA+oqxB+aac(6′)-Ib-cr+ermB+floR(14株,11.7%)和bla_(TEM)+bla_(CTX-M)+qnrA+oqxA+oqxB+ermB+floR(13株,10.8%)。耐药基因和耐药表型相关性分析结果显示,bla_(TEM)和bla_(CTX-M)与大肠杆菌对头孢氨苄耐药情况极显著相关(P0.01),bla_(CTX-M)与大肠杆菌对头孢拉啶和头孢曲松耐药情况极显著相关(P0.01),qnrA、oqxA、oqxB和aac(6′)-Ib-cr基因与大肠杆菌对诺氟沙星、氧氟沙星、恩诺沙星和环丙沙星耐药极显著相关(P0.01),aac(6′)-Ib-cr基因与大肠杆菌对庆大霉素和卡那霉素耐药极显著相关(P0.01),floR基因与大肠杆菌对氟苯尼考耐药情况极显著相关(P0.01)。本研究结果表明广西规模化猪场猪源大肠杆菌仅对极少数抗菌药物具有较高敏感率,多重耐药情况严重,具有丰富的耐药谱型,携带多种耐药基因且具有复杂的基因组合类型,所携带的耐药基因与其耐药表型具有一定的相关性。  相似文献   

9.
为研究肉鸡生产链中弯曲杆菌的流行规律,从广东省广州市、佛山市的家禽养殖场、屠宰场和市场中采集了1 414份样本,通过分离细菌、检测耐药性及耐药基因等方法分析该病的流行规律。结果显示:共分离出201株弯曲杆菌,阳性率为14.21%,且养殖场(25.1%)到屠宰场(11.9%)到市场(7.1%)的弯曲杆菌污染率呈现递减趋势;弯曲杆菌分离株对喹诺酮类和磺胺类药物具有高耐药率且喹诺酮类药物耐药菌株的gyrA基因QRDR区域发生了C257T的突变,突变率为100%;大环内酯类药物耐药菌株的23 S rRNA基因均发生了A2075G点突变。此外,大环内酯类耐药株的甲基化酶耐药基因ermB的携带率为52.38%,四环素类药物耐药株的tet(O)基因的携带率为97.37%。研究表明广东省部分地区禽源弯曲杆菌对喹诺酮类耐药率高且多重耐药情况普遍,提示加强禽源弯曲杆菌耐药基因的监测。  相似文献   

10.
为了检测确定2019年5月河南某规模化猪场一栋保育仔猪发病猪群的病原,本研究从送检的发病猪关节液中分离获得1株细菌。通过细菌纯化培养、革兰氏染色、形态学观察及猪链球菌gdh基因PCR扩增,确定该分离菌株为猪链球菌。用猪链球菌分型引物对该菌株进行PCR扩增分型鉴定及软件比对分析,结果表明该分离菌株为猪链球菌14型,与猪链球菌JS14株（GenBank登录号：CP002465.1）同源性为100%。毒力基因检测结果表明,该菌株的同时携带有epf、mrp、sly、fbps、orf2毒力基因,属于高致病性菌株。小鼠致病性试验结果也证明该菌株是一株高致病性猪链球菌。药物敏感性试验结果显示,该菌株对β内酰胺类和喹诺酮类药物敏感,对氨基糖苷类、四环素类、大环内酯类和磺胺类高度耐药,表现出多重耐药现象。对该菌株进行5大类24种耐药基因检测,该菌株同时携带有blaTEM、aadA1、strA、strB、aacC2、aphA1、tet（B）、gyrA、parC、sul2耐药基因。该研究为后续进一步开展猪链球菌14型流行特点和致病机制研究奠定了基础,为猪链球菌14型临床防控提供了理论依据,同时具有重要的公共卫生意义。  相似文献   

11.
Eighty-seven Streptococcus suis isolates recovered in 1999-2000 from diseased pigs, all from different farms, were screened for resistance against macrolide and lincosamide antibiotics by the disk diffusion and agar dilution test and a PCR assay, amplifying the ermB gene and the mefA/E gene. Seventy-one percent of the isolates showed constitutive resistance to macrolide and lincosamide antibiotics (MLS(B)-phenotype). All these isolates were positive for the ermB gene in the PCR, but negative for the mefA/E gene. For all strains minimum inhibitory concentrations (MIC) against five other antimicrobial agents were determined. All strains were susceptible to penicillin. Ninety-nine percent of the isolates were susceptible to enrofloxacin and tiamulin. Eighty-five percent of the strains were resistant to doxycycline. A 540bp fragment of the ermB genes of eight S. suis strains was sequenced and compared with ermB genes of five S. pneumoniae and five S. pyogenes strains of human origin. A 100% homology was found between these fragments in seven S. suis, one S. pneumoniae and three of the S. pyogenes isolates. This study demonstrates that resistance against macrolides, lincosamides and streptogramin B is widespread in S. suis and mediated by ribosome methylation, encoded by the ermB gene.  相似文献   

12.
动物源性链球菌红霉素耐药基因的分布   总被引：6，自引：1，他引：6  
致病性链球菌可导致人和动物的各种化脓性疾病、肺炎、乳腺炎、败血症等，且部分致病性链球菌是重要的人畜共患病病原，对人畜健康均造成极大危害，已引起高度重视。大环内酯类抗生素作为青霉素药物的替代药物是治疗致病性链球菌感染的有效药物。国内外对人医重要的链球菌诸如肺炎球菌、化脓性链球菌的研究表明，临床分离株对大环内酯类抗生素的耐药率较高，  相似文献   

13.
Fifty-four quinupristin/dalfopristin-resistant Enterococcus faecium (QDREF) isolated from chickens and pigs during 2002-2003 in Korea were screened by PCR for the presence of streptogramin resistance genes vatD, vatE, and vgbA, and macrolide resistance gene ermB. None of the QDREF isolates carried vgbA and vatD genes, while vatE and ermB were detected in 9.2% and 74% of the isolates, respectively. Twenty-six percent (14/54) of the QDREF isolates contained none of the resistance determinants tested. Pulsed-field gel electrophoresis (PFGE) patterns revealed high heterogeneity: 47 different patterns for 54 QDREF evaluated. Identical PFGE types were observed in two pairs of chicken isolates and a pair of pig isolates, respectively, but chicken isolates did not share PFGE pattern with pig isolates, suggesting clonal spread of QDREF strain between the same species of animals but not between different species of animals. This is the first report, to our knowledge, of vatE-positive E. faecium isolates and also the first evidence of clonal spread of QDREF strain between animals in Korea.  相似文献   

14.
Environmental streptococcus isolates from bovine milk were identified to the species and strain level and screened for resistance to macrolide and lincosamide antibiotics by phenotypic and genotypic methods. Isolates were tested for resistance to erythromycin and pirlimycin by broth microdilution assays. Presence of ribosomal methylase genes (ermA, ermB, ermC) and efflux pump genes (mefA/E, msrA/C) was detected by polymerase chain reaction (PCR). Resistance to pirlimycin (minimum inhibitory concentration (MIC) = 8microg/ml) was detected in 6 of 13 Enterococcus isolates that were identified as E. faecium by API20Strep typing. msrC was detected in 10 enterococcal isolates but the detection of msrC was not associated with phenotypic resistance. msrC negative isolates were reclassified as Enterococcus mundtii based on sequencing of housekeeping genes. Resistance to erythromycin and pirlimycin (MIC > 16microg/ml) was detected in 4 of 4 Streptococcus dysgalactiae and 12 of 20 Streptococcus uberis isolates and was encoded by ermB. All Streptococcus isolates tested negative for ermA, ermC, mefA/E and msrA/C. Among ermB positive streptococci, three alleles were identified based on a 527 bp gene fragment. Each allele was detected in at least two herds. The same alleles have also been detected in other bacterial species from bovine and non-bovine hosts and farm soil, suggesting a theoretical potential for horizontal transfer of macrolide resistance genes on dairy farms.  相似文献   

15.
Antibacterial agents such as zinc bacitracin (ZB) and virginiamycin (VG) are used as growth promoting agents (GP) in broiler chicken production. The objective of this study was to evaluate the effect of the use of ZB and VG on the emergence of antibacterial resistance in a commercial broiler chicken farm. Three trials were conducted using 3 different diets: one without antibacterial agents, one containing VG, and one with ZB. Escherichia coli and Enterococcus spp. strains were isolated and tested for their susceptibility to various antibacterial agents. The occurrence of the resistance genes vatD, ermB, and bcrR in Enterococcus spp. isolates was determined by polymerase chain reaction (PCR). Comparative quantification of vatD and bcrR genes in total deoxyribonucleic acid (DNA) extracts from litter was done by SYBR Green Real-Time PCR (QPCR). Escherichia coli and Enterococcus spp. isolates from diet groups had different levels of resistance to various antibacterial agents over time. These GPs did not select for specific antibacterial agent resistance (AAR) in Enterococcus spp. The use of GPs seemed to lower the percentage of E. coli isolates resistant to some antibacterial agents. The presence of the bcrR gene could not explain all resistant phenotypes to ZB. Genes other than vatD and ermB might be involved in the resistance to VG in Enterococcus spp. Use of GPs was not associated with presence of the bcrR gene in DNA extracts from litter, but use of VG was associated with vatD presence.  相似文献   

16.
Campylobacter has become the leading cause of zoonotic enteric infections in developed and developing countries world-wide. Antimicrobial resistance has emerged among Campylobacter mainly as a consequence of the use of antimicrobial agents in food animal production. Resistance to drugs of choice for the treatment of infections, macrolides and fluoroquinolones has emerged as a clinical problem and interventions to reduce this are recommended. Resistance to fluoroquinolones and macrolides is mediated by chromosomal mutations. Resistance to other relevant antimicrobial agents, mediated by acquired resistance genes, has not become widespread so far. However, resistance genes originating from both Gram-positive and Gram-negative bacterial species have been found, showing the potential for acquired resistance to emerge in Campylobacter.  相似文献   

17.
Clostridium perfringens is a well documented cause of a mild self-limiting diarrhea and a potentially fatal acute hemorrhagic diarrheal syndrome in the dog. A recent study documented that 21% of canine C. perfringens isolates had MIC's indicative of resistance to tetracycline, an antimicrobial commonly recommended for treatment of C. perfringens-associated diarrhea. The objective of the present study was to further evaluate the antimicrobial susceptibility profiles of these isolates by determining the prevalence of specific resistance genes, their expression, and ability for transference between bacteria. One hundred and twenty-four canine C. perfringens isolates from 124 dogs were evaluated. Minimum inhibitory concentrations of tetracycline, erythromycin, tylosin, and metronidazole were determined using the CLSI Reference Agar Dilution Method. All isolates were screened for three tetracycline resistance genes: tetA(P), tetB(P) and tetM, and two macrolide resistance genes: ermB and ermQ, via PCR using primer sequences previously described. Ninety-six percent (119/124) of the isolates were positive for the tetA(P) gene, and 41% (51/124) were positive for both the tetA(P) and tetB(P) genes. No isolates were positive for the tetB(P) gene alone. Highly susceptible isolates (MIC< or = 4 microg/ml) were significantly more likely to lack the tetB(P) gene. One isolate (0.8%) was positive for the ermB gene, and one isolate was positive for the ermQ gene. The tetM gene was not found in any of the isolates tested. Two out of 15 tested isolates (13%) demonstrated transfer of tetracycline resistance via bacterial conjugation. Tetracycline should be avoided for the treatment of C. perfringens-associated diarrhea in dogs because of the relatively high prevalence of in vitro resistance, and the potential for conjugative transfer of antimicrobial resistance.  相似文献   

18.
Distillers grains, a coproduct of ethanol production from cereal grains, are composed principally of the bran, protein, and germ fractions and are commonly supplemented in ruminant diets. The objective of this study was to assess the effect of feeding wet distillers grains with solubles (WDGS) and monensin and tylosin on the prevalence and antimicrobial susceptibilities of fecal foodborne and commensal bacteria in feedlot cattle. Cattle were fed 0 or 25% WDGS in steam-flaked corn-based diets with the addition of no antimicrobials, monensin, or monensin and tylosin. Fecal samples were collected from each animal (n = 370) on d 122 and 136 of the 150-d finishing period and cultured for Escherichia coli O157. Fecal samples were also pooled by pen (n = 54) and cultured for E. coli O157, Salmonella, commensal E. coli, and Enterococcus species. Antimicrobial resistance was assessed by determining antimicrobial susceptibilities of pen bacterial isolates and quantifying antimicrobial resistance genes in fecal samples by real-time PCR. Individual animal prevalence of E. coli O157 in feces collected from cattle fed WDGS was greater (P < 0.001) compared with cattle not fed WDGS on d 122 but not on d 136. There were no treatment effects on the prevalence of E. coli O157 or Salmonella spp. in pooled fecal samples. Antimicrobial susceptibility results showed Enterococcus isolates from cattle fed monensin or monensin and tylosin had greater levels of resistance toward macrolides (P = 0.01). There was no effect of diet or antimicrobials on concentrations of 2 antimicrobial resistance genes, ermB or tetM, in fecal samples. Results from this study indicate that WDGS may have an effect on the prevalence of E. coli O157 and the concentration of selected antimicrobial resistance genes, but does not appear to affect antimicrobial susceptibility patterns in Enterococcus and generic E. coli isolates.  相似文献   

19.
This study investigated and compared the antimicrobial resistance patterns and ribotypes of Staphylococcus aureus isolated from pig tonsils and cow’s milk in China. A total of 90 isolates of S. aureus was included: 42 strains were isolated from tonsils of pigs and 48 from half-udder milk. The broth microdilution method and the double-disc diffusion test (D test) were used for antimicrobial susceptibility testing. The mecA gene for methicillin-resistant S. aureus (MRSA) and the ermA, ermB, ermC, and msrA genes for erythromycin-resistant strains were detected by polymerase chain reaction (PCR). The isolates were ribotyped with the Riboprinter system. The highest frequency of resistance was observed with clindamycin (91.1%), followed by penicillin (90.0%), and erythromycin (85.6%). All strains were susceptible to vancomycin and trimethoprim-sulfamethoxazole. The D test showed that 54.5% (42/77) of erythromycin-resistant isolates had the constitutive resistance phenotype and 45.5% (35/77) had the inducible resistance phenotype to clindamycin. A higher proportion of resistance to cephalosporins, macrolides, fluoroquinolones, and pleuromutilins was observed in pig isolates than in milk isolates (P < 0.05). The mecA gene was detected in all MRSA isolates; 89.6% of erythromycin-resistant strains harbored the ermC gene and 16.9% harbored the ermB gene. A total of 35 different ribogroups was found among the isolates investigated; 83.3% of pig strains belonged to 1 cluster with a similarity coefficient of 0.84. In contrast, 3 main clusters were observed among 68.8% of milk strains, which indicates a high degree of host specificity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号