共查询到20条相似文献,搜索用时 15 毫秒
1.
Adriana Hamond Regua-Mangia Alice Gon?alves M. Gonzalez Aloysio M. F. Cerqueira Jo?o Ramos C. Andrade 《Journal of veterinary science (Suw?n-si, Korea)》2012,13(2):139-144
Escherichia (E.) coli serotype O157:H7 is a globally distributed human enteropathogen and is comprised of microorganisms with closely related genotypes. The main reservoir for this group is bovine bowels, and infection mainly occurs after ingestion of contaminated water and food. Virulence genetic markers of 28 O157:H7 strains were investigated and multilocus enzyme electrophoresis (MLEE) was used to evaluate the clonal structure. O157:H7 strains from several countries were isolated from food, human and bovine feces. According to MLEE, O157:H7 strains clustered into two main clonal groups designated A and B. Subcluster A1 included 82% of the O157:H7 strains exhibiting identical MLEE pattern. Most enterohemorrhagic E. coli (EHEC) O157:H7 strains from Brazil and Argentina were in the same MLEE subgroup. Bovine and food strains carried virulence genes associated with EHEC pathogenicity in humans. 相似文献
2.
3.
Tan Duc Nguyen Thin Thanh Vo Hung Vu-Khac 《Journal of veterinary science (Suw?n-si, Korea)》2011,12(2):159-164
This study was conducted to determine the prevalence and characteristics of pathogenic Escherichia (E.) coli strains from diarrheic calves in Vietnam. A total of 345 E. coli isolates obtained from 322 diarrheic calves were subjected to PCR and multiplex PCR for detection of the f5, f41, f17, eae, sta, lt, stx1, and stx2 genes. Of the 345 isolates, 108 (31.3%) carried at least one fimbrial gene. Of these 108 isolates, 50 carried genes for Shiga toxin and one possessed genes for both enterotoxin and Shiga toxin. The eae gene was found in 34 isolates (9.8%), 23 of which also carried stx genes. The Shiga toxin genes were detected in 177 isolates (51.3%) and the number of strains that carried stx1, stx2 and stx1/stx2 were 46, 73 and 58, respectively. Among 177 Shiga toxin-producing E. coli isolates, 89 carried the ehxA gene and 87 possessed the saa gene. Further characterization of the stx subtypes showed that among 104 stx1-positive isolates, 58 were the stx1c variant and 46 were the stx1 variant. Of the 131 stx2-positive strains, 48 were stx2, 48 were stx2c, 11 were stx2d, 17 were stx2g, and seven were stx2c/stx2g subtypes. The serogroups most prevalent among the 345 isolates were O15, O20, O103 and O157. 相似文献
4.
Yao ZOU Xiaoming ZHU Hassan Mushtaq MUHAMMAD Ping JIANG Yufeng LI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(6):653-660
Recently, a series of acute swine erysipelas outbreaks occurred in Eastern China. Eight
strains isolated from cases of septicemia were determined as serotype 1a, and 4 of the
isolates were resistant to acriflavine. One isolate strain named was attenuated
on agar media containing acriflavine dye. The 432-bp hypervariable region in
spaA gene of the field and attenuated strains were amplified and
sequenced. It was further compared with the vaccine strain G4T10,
and thus, the eight field strains can be divided into four spaA-types.
The partial spaA gene analysis also showed that no point mutations
occurred among different archived passages of HX130709 during the attenuation. Results of
pulsed-field gel electrophoresis showed that eight distinct patterns with 22 to 30 DNA
fragment bands were produced from field strains, and twelve distinct patterns with 23 to
27 DNA fragment bands were produced from different passages of the attenuated strains.
Mouse pathogenicity test showed that the mortality of the mice infected with
104 CFU field strains was 100% and the attenuation of strain HX130709
occurred between 46 and 50 passages. All the field and attenuated strains were highly
sensitive to β-lactam antibiotics, tetracyclines and macrolides. So, we can make
conclusions that the acute swine erysipelas outbreaks in Eastern China were caused by
serotype 1a E. rhusiopathiae strains with different biochemical
characteristics, and the virulence of serotype 1a E. rhusiopathiae
strains is unrelated with some point mutations in 432-bp hypervariable region of the
spaA gene. HX130709相似文献
5.
试验从鸡场周围环境中采集土样,在伊红美蓝培养基平板上分离纯化大肠杆菌,然后以其为宿主,分离相应的噬菌体,并研究其生物学特性。结果表明,共分离到大肠杆菌4株,经16S rDNA鉴定为埃希氏大肠杆菌。其中,以大肠杆菌LY4为宿主分离纯化到1株烈性噬菌体,负染经电镜观察该噬菌体由多面体头部及尾部组成,噬菌斑直径为2.5~3.8 mm,效价2.0×1010 PFU/mL,最佳感染复数为0.0001;在温度-20~37 ℃、pH 5.0~10.0范围内该噬菌体表现出良好的稳定性,但在人工胃液(pH 1.2)条件下,即可导致死亡;测定其一步生长曲线,该噬菌体潜伏期为20 min,裂解能力强,以上特性表明该噬菌体在鸡舍环境治理中具有潜在的应用价值。 相似文献
6.
Enterohemorrhagic Escherichia coli serotype O157:H7 is a pathotype of diarrheagenic E. coli that produces one or more Shiga toxins, forms a characteristic histopathology described as attaching and effacing lesions, and possesses the large virulence plasmid pO157. The bacterium is recognized worldwide, especially in developed countries, as an emerging food-borne bacterial pathogen, which causes disease in humans and in some animals. Healthy cattle are the principal and natural reservoir of E. coli O157:H7, and most disease outbreaks are, therefore, due to consumption of fecally contaminated bovine foods or dairy products. In this review, we provide a general overview of E. coli O157:H7 infection, especially focusing on the bacterial characteristics rather than on the host responses during infection. 相似文献
7.
Shao-Kuang CHANG Dan-Yuan LO Hen-Wei WEI Hung-Chih KUO 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(1):59-65
This study determined the
antimicrobial resistance profiles of Escherichia coli isolates from dogs
with a presumptive diagnosis of urinary tract infection (UTI). Urine samples from 201 dogs
with UTI diagnosed through clinical examination and urinalysis were processed for
isolation of Escherichia coli. Colonies from pure cultures were
identified by biochemical reactions (n=114) and were tested for susceptibility to 18
antimicrobials. The two most frequent antimicrobials showing resistance in Urinary
E. coli isolates were oxytetracycline and ampicillin. Among the
resistant isolates, 17 resistance patterns were observed, with 12 patterns involving
multidrug resistance (MDR). Of the 69 tetracycline-resistant E. coli
isolates, tet(B) was the predominant resistance determinant and was
detected in 50.9% of the isolates, whereas the remaining 25.5% isolates carried the
tet(A) determinant. Most ampicillin and/or amoxicillin-resistant
E. coli isolates carried blaTEM-1 genes.
Class 1 integrons were prevalent (28.9%) and contained previously described gene cassettes
that are implicated primarily in resistance to aminoglycosides and trimethoprim
(dfrA1, dfrA17-aadA5). Of the 44 quinolone-resistant
E. coli isolates, 38 were resistant to nalidixic acid, and 6 were
resistant to nalidixic acid, ciprofloxacin and enrofloxacin. Chromosomal point mutations
were found in the GyrA (Ser83Leu) and ParC (Ser80Ile) genes. Furthermore, the
aminoglycoside resistance gene aacC2, the chloramphenicol resistant gene
cmlA and the florfenicol resistant gene floR were also
identified. This study revealed an alarming rate of antimicrobial resistance among
E. coli isolates from dogs with UTIs. 相似文献
8.
9.
10.
Initial adherence to host cells is the first step of the infection of enteropathogenic Escherichia coli (EPEC), enterohaemorrhagic Escherichia coli (EHEC) and verotoxigenic Escherichia coli (VTEC) strains. The importance of this step in the infection resides in the fact that (1) adherence is the first contact between bacteria and intestinal cells without which the other steps cannot occur and (2) adherence is the basis of host specificity for a lot of pathogens. This review describes the initial adhesins of the EPEC, EHEC and VTEC strains. During the last few years, several new adhesins and putative colonisation factors have been described, especially in EHEC strains. Only a few adhesins (BfpA, AF/R1, AF/R2, Ral, F18 adhesins) appear to be host and pathotype specific. The others are found in more than one species and/or pathotype (EPEC, EHEC, VTEC). Initial adherence of EPEC, EHEC and VTEC strains to host cells is probably mediated by multiple mechanisms. 相似文献
11.
12.
This study was conducted to investigate the presence of Escherichia (E.) coli O157 and E. coli O157:H7 and stx1 and stx2 genes on cattle carcasses and in rectal samples collected from Samsun Province of Turkey. A total of 200 samples collected from cattle carcasses and the rectal contents of 100 slaughtered cattle from two commercial abattoirs were tested using the immunomagnetic separation technique and multiplex PCR methods. E. coli O157 and E. coli O157:H7 were detected in 52 of the 200 samples (26%) tested. Of the positive samples, 49 were E. coli O157 and three were E. coli O157:H7. The E. coli O157 strain was isolated from 24 carcasses and 25 rectal samples, while E. coli O157:H7 was isolated from two carcasses and one rectal sample. Of the 49 samples positive for E. coli O157, 32 were from the rectal and carcass samples of the same animal, while two E. coli O157:H7 isolates were obtained from rectal swabs and carcasses of the same animal. The stx1 and stx2 genes were both detected in 35 E. coli O157 isolates and one E. coli O157:H7 isolate, but the stx2 gene was only detected alone in two E. coli O157 isolates. Overall, 16 carcasses tested positive for E. coli O157 and one carcass tested positive for E. coli O157:H7 based on both carcass and rectal samples. Overall, the results of this study indicate that cattle carcasses pose a potential risk to human health due to contamination by E. coli O157 and E. coli O157:H7 in the feces. 相似文献
13.
为分析广东地区猪源大肠杆菌耐药性及其系统进化背景,试验于2011年从患病猪分离出264株大肠杆菌,包括粪便源131株和肝源133株,采用琼脂稀释法测定18种抗菌药物的敏感性,多重PCR法确定系统进化关系,并对不同来源菌株的耐药性和系统进化背景进行分析比较。结果发现,大肠杆菌多重耐药现象严重,共存在128种耐药谱型。分离菌株对氨苄西林、复方新诺明、萘啶酸和四环素高度耐药,对黏菌素、头孢他啶和阿米卡星较敏感。种群进化分析结果表明,分离菌株主要分布在共生型的A组和B1组(91.66%),且不同来源菌株的种群进化分布差异不显著(P>0.05)。结合药敏试验结果发现,不同进化组别的分离菌株对特定抗菌药物的耐药性存在显著差异(P<0.05)。通过对大肠杆菌耐药性及其系统发育群进行综合分析,为兽医临床用药提供依据。 相似文献
14.
15.
Irfan Ahmad MIR Bablu KUMAR Anil TAKU Farah FARIDI Mohd. Altaf BHAT Naseer Ahmad BABA Tahir MAQBOOL 《Journal of Equine Science》2013,24(3):53-55
Present study was undertaken to study the prevalence of β-haemolytic streptococci in
equine of northern temperate region of Jammu and Kashmir, India. One hundred and forty one
samples were collected in duplicate from nasopharyngeal tract of diseased (53) and
apparently healthy equine (88) for isolation and direct PCR. A total of 77 isolates of
streptococci were recovered from 141 samples with an overall prevalence rate of 54.60%.
Out of these 77 isolates, 52 were from diseased and 25 from apparently healthy animals. Of
the 77 isolates, 4 were identified as Streptococcus equi subsp.
equi, 56 as S. equi subsp.
zooepidemicus and 17 as S. dysgalactiae subsp.
equisimilis. Thus the overall prevalence of S. equi subsp.
equi, S. equi subsp. zooepidemicus
and S. dysgalactiae subsp. equisimilis was 2.83, 39.71
and 12.05% respectively. The sensitivity of the PCR for the detection of S.
equi species was found higher when attempted from direct swab samples. 相似文献
16.
本试验旨在调查新疆石河子地区奶牛乳房炎源大肠杆菌的某些生物学特性及其耐药状况,以提高药物疗效,减少牛奶中药物的残留。试验从新疆石河子地区患乳房炎奶牛的乳样中分离纯化并鉴定出21株大肠杆菌,并对大肠杆菌分离株进行抗菌药物敏感性分析。结果表明,21株大肠杆菌对21种抗菌药物中的6种药物耐药率超过50%,其中最多的耐药15种,最少的耐药5种,耐药6及6种以上的菌株共占到76.19%。提示,该地区奶牛乳房炎源大肠杆菌对多种药物已产生了不同程度的耐药性,且存在严重的多重耐药情况。 相似文献
17.
Plasma metabolomic profiles and immune responses of piglets after weaning and challenge with E. coli
Background
The processes of weaning and exposure to pathogenic bacteria induce stress responses, which may alter the metabolism. In this study, we investigated the changes in plasma metabolites and immune responses in piglets in response to the stress induced by weaning and Escherichia coli challenge.Results
Fecal dry matter decreased (P = 0.003) and nearly half (44.4%) the piglets developed diarrhea on day 2 and 3 postweaning. The concentration of plasma immunoglobulin A was higher (P < 0.001) on day 11 postweaning than on day 0 or 4 postweaning. The levels of white blood cells increased continuously (P < 0.001) from day 0 to day 11 postweaning. Differences in the percentages of neutrophils (P = 0.029) and lymphocytes (P = 0.022) were seen, but the neutrophil/lymphocyte ratio did not differ in the period after weaning. A clear separation of the metabolomic profile data for day 0 and day 4 postweaning was observed with a principal components analysis (PCA) scores plot, and the data for day 11 were located between those for day 0 and day 4 postweaning. The plasma levels of proline, taurine, and carnitine were higher, whereas those of betaine, creatine, L-arginine and acetylcarnitine were lower on day 4 postweaning than on day 0. Levels of lysophosphatidylcholine and phosphatidylcholine were either higher or lower after weaning, depending on the chain lengths or characters of these metabolites.Conclusions
Our results show a clear separation in the plasma metabolomic profiles of piglets that corresponded to the fecal responses to stress on the piglets induced by weaning or exposure to a pathogen (E. coli). These plasma metabolite profiles suggest that the challenges induced proinflammatory responses in the piglets, resulting in postweaning diarrhea, which was associated with higher concentrations of IgA in the plasma. 相似文献18.
19.
Parisi A Lanzilotta SG Addante N Normanno G Di Modugno G Dambrosio A Montagna CO 《Veterinary research communications》2007,31(1):113-123
Eleven cattle farms, 8 layer farms, 7 broiler farms and 30 broiler meat samples were investigated in south-eastern Italy throughout
2003 to evaluate the prevalence, the molecular type and antimicrobial resistance of thermophilic Campylobacters. A total of
398 samples were analysed. One Campylobacter isolate for each positive faecal swab and three isolates per positive broiler meat sample were selected for further analysis.
Multiplex PCR was performed for species-level identification and PCR-RFLP of the flagellin A gene for genotyping. Resistance
to 14 antimicrobials was studied in 188 Campylobacter isolates. Prevalence of campylobacters was high both on farms (100%) and in food samples (73%). On 4/11 cattle farms and
on 10/15 poultry farms more than one species was isolated. The presence of more than one genotype was found on 8/11 cattle
farms, on 10/15 poultry farms and in 8/22 Campylobacter-positive food samples. High rates of resistance to quinolone were observed: 9/31 (29%) C. jejuni bovine isolates, 4/22 (18%) C. jejuni poultry isolates, and 14/26 (54%) C. coli poultry isolates. Resistance to sulphamethoxazole-trimethoprim was also observed frequently: 18/26 (69%) of the avian C. coli strains, 25/31 (80%) of the C. jejuni strains isolated from poultry and 15/22 (68%) of those isolated from cattle were resistant. There was a significant difference
between the rate of resistance to macrolides of C. coli and C. jejuni isolated in poultry, which amounted to 23% and 3%, respectively. This study provided data on the prevalence and antimicrobial
resistance of thermophilic campylobacters in south-eastern Italy and confirmed that flaA-typing is an efficient tool to study the epidemiology of Campylobacter strains in short-term investigations. 相似文献
20.
Ling-Cong KONG Duo GAO Yun-Hang GAO Shu-Ming LIU Hong-Xia MA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2014,76(12):1655-1657
The minimum inhibitory
concentrations (MICs), mutation prevention concentrations (MPCs) and contribution of
quinolone resistance-determining region (QRDR) mutations to fluoroquinolone
(ciprofloxacin, enrofloxacin and orbifloxacin) susceptibility in 23 Pasteurella
multocida (Pm) isolates were investigated.
Fluoroquinolone-susceptible isolates (MICs ≤0.25 µg/ml,
9 isolates) had no QRDR mutations, and their respective MPCs were low.
Fluoroquinolone-intermediate isolates (MICs=0.5 µg/ml,
14 isolates) had QRDR mutations (Asp87 to Asn or Ala84 to Pro in gyrA),
and their respective MPCs were high (4–32 µg/ml).
First-step mutants (n=5) and laboratory-derived highly resistant fluoroquinolone mutants
(n=5) also had QRDR mutations. The MICs of fluoroquinolones for mutant-derived strains
were decreased in the presence of efflux inhibitors. The results indicated that the
fluoroquinolone resistance of Pm is mainly due to multiple target gene
mutations in gyrA and parC and the overexpression of
efflux pump genes. 相似文献