Characterization of Escherichia coli isolated from cases of avian colibacillosis.

Forty-four western Canadian isolates of Escherichia coli associated with colibacillosis of turkeys and chickens were examined for serotype, antibiotic resistance, and production of aerobactin. The isolates belonged to fourteen O serogroups, with 39% of the strains being non-typeable. A high frequency of resistance to tetracycline, kanamycin, neomycin, cephalothin, streptomycin and erythromycin was observed. Most isolates produced aerobactin. Ten E. coli belonging to serogroups O1, O2 and O78 were also examined for pili production, hemagglutination, serum sensitivity, production of iron-regulated outer membrane proteins (IROMPS), and virulence. All isolates examined produced pili, exhibited mannose-sensitive hemagglutination of avian red blood cells and produced IROMPS under iron-restricted growth conditions. The five isolates of serogroup O1 and O2 were resistant to killing by turkey serum and were highly virulent. Only two of the five isolates of serogroup O78 were serum resistant. No correlation between serum resistance and virulence was observed in serogroup O78.     

Prevalence of fimbrial antigens and enterotoxins in nonclassical serogroups of Escherichia coli isolated from newborn pigs with diarrhea

Ninety-nine nonclassical serogroups isolated from newborn pigs with neonatal diarrhea were tested for fimbrial antigens F4(K88), F5(K99), F6(987P), F41, and F165, and for heat-labile enterotoxin, heat-stable enterotoxin a (STa), heat-stable enterotoxin b, verocytotoxin, and cytolethal-distending toxin. Thirty-two strains, belonging mostly to serogroups O64:K"V142,", O9:K103, and O20:K101, were F5-positive and usually produced STa, although 5 strains produced only heat-stable enterotoxin b. Fifteen strains, belonging mostly to serogroups O64:K"V142" and O20:K101, were F41 positive and usually produced STa. Twenty-three stains, belonging mostly to serogroups O64:K"V142," O9:K103, and O20:K101, were F6-positive and usually produced STa. Several strains produced more than one fimbrial antigen, either F5 and F41, F5 and F6, F6 and F41, F6 and F165, or F5, F6, F41, and F165. None of the strains produced heat-labile enterotoxin, verocytotoxin, or cytolethal-distending toxin. The indirect immunofluorescence test was much more sensitive than was the slide agglutination test for the detection of each of the fimbrial antigens F5, F6, F41, and F165 on strains grown in vitro. The production of F6 by certain strains for which only a low proportion of cells were F6-positive in vitro, as demonstrated by immunofluorescence, was confirmed by experimental infection of newborn pigs.     

Virulence factors of avian pathogenic Escherichia coli strains isolated from chickens with colisepticemia in Japan

The virulence factors of avian pathogenic Escherichia coli (APEC) isolated in Japan were investigated. Serogroups O, serotypes K1 and K5, and genes cva C, iss, iutA, papA, tsh, and usp, which have been thought to be related to virulence, were examined for their association with E. coli strains isolated from diseased and healthy chickens. The frequently recognized serogroups O1, O2, and O78 were found in 56 of 125 (44.8%) strains of diseased chickens (APEC) versus 13 of 100 (13.0%) strains of healthy chickens (commensal E. coli), a significant difference at risk ratio < 0.01. Although iss, iutA, and tsh were widely distributed in the APEC irrespective of O serogroup, papA, usp, and the K1 serotype were detected in serogroup O2 of APEC. The kfiD gene related to the K5 capsule and VT, LT, and ST genes related to exotoxins were not detected in any strains examined.     

禽致病性大肠杆菌的分离、O血清群鉴定及药物敏感试验

对2005年5月~2016年3月自河北、山东、河南、江苏、陕西、辽宁等省发病鸡场疑似大肠杆菌病的病死鸡病变部位分离的194株禽致病性大肠杆菌进行了生化特性测定、O抗原血清群鉴定及药敏试验。试验用5种大肠杆菌单因子（O1、O2、O57、O65、O78）阳性血清进行O血清群鉴定,确定了124株O血清群,占鉴定菌株数的63.9%（124/194）,其中O1 3株、O2 26株、O57 15株、O65 47株和O78 33株,O65和O78为优势菌株,而O2和O57血清群菌株次之,O1血清群菌株最少。8种药物（氨苄西林、新霉素、多西环素、磺胺间甲氧嘧啶、替米考星、环丙沙星、头孢噻呋和氟苯尼考）的药敏试验结果表明,受试的5株大肠杆菌分离株均对环丙沙星和新霉素敏感,而对其他药物均有不同程度的耐受。本研究结果表明O65、O78、O2和O57血清群高度流行,为进一步研发多价菌苗奠定了基础。     

Isolation,O Serogrouping and Drug Sensitivity Test of Avian Pathogenic Escherichia coli

One hundred and ninety four avian pathogenic Escherichia.coli (APEC) isolated from different pathotypes of chickens in Hebei province,Shandong province,Henan province,Jiangsu province,Shanxi province and Liaoning province in China between May 2005 and March 2016 were investigated by determination of biochemical characters,O serogroup identification and drug sensitivity test.Out of 194 isolates, 124 strains(63.9%) could be grouped to serogroups O1(3),O2(26),O57(15),O65(47) and O78(33).The drug sensitivity test used eight antibiotics (ampicillin, neomycin, doxycycline, sulfamonomethoxine,tilmicosin,ciprofloxacin ceftiofur and florfenicol) by one strain of O1,O2,O57,O65,O78 serogroup,respectively.The results showed that all strains were sensitive to ciprofloxacin and neomycin, and resistance to other drugs at varying degrees.This study demonstrated that the high prevalence of O65,O78,O2 and O57 isolates existed and provided the basis for the development of multivalent bacterin in future.     

Fimbriae and enterotoxins associated with Escherichia coli serogroups isolated from pigs with colibacillosis

A comprehensive study of 223 Escherichia coli isolates from pigs with colibacillosis included determination of O serogroups, detection of heat-labile enterotoxin, heat-stable enterotoxin (STa and STb), and identification of K88, K99, 987-P, F-41, and type 1 fimbriae. The incidence of the various E coli types among isolates of pigs of different ages was also determined. Escherichia coli bearing K88 fimbriae accounted for 48% of all isolates studied, were most often of serogroup O157, O149, or O8, and usually produced labile toxin alone or in combination with STa or STb. These E coli were commonly isolated from pigs in each age group studied (0 to 5 days, 6 to 10 days, 11 to 24 days, and greater than 24 days). Escherichia coli bearing 987-P accounted for 30% of the isolates, were most often of serogroup O141 or O20, and usually produced STa. Escherichia coli bearing K99 accounted for 13% of the isolates, usually were of serogroup O101 or O8, and almost always produced STa. Escherichia coli bearing 987-P or K99 were most often isolated from pigs less than 6 days of age. Fimbriae F-41, when identified, were usually on E coli of serotype O101:K99. Although infrequently found, type 1 fimbriae were on E coli of most of the serogroups identified in this study.     

Characterisation and quantitation of pilus antigens of Moraxella bovis by ELISA

Hyperimmune serums raised in rabbits to purified pili from 9 Australian and 2 American strains of Moraxella bovis from infectious bovine keratoconjunctivitis (IBK) affected herds were used to study the degree of binding between combinations of antigen and antiserum in a conventional enzyme linked immunosorbent assay (ELISA). With the aid of appropriate absorption tests major antigenic differences among pili were found permitting 6 distinct serogroups to be recognised. Further, production of specific antiserums to representative strains of each serogroup in goats facilitated the development of a double antibody sandwich ELISA which could be used to quantitate pilus expression of a given strain of M. bovis, or to differentiate pilus serogroups of 22 strains of M. bovis obtained from a total of 12 Australian herds. Most isolates were found to belong to serogroups designated IV and V. One strain from the United States of America showed total homology with Australian serogroup IV while the other showed some cross-reactivity with serogroups V and VI.     

The protective efficacy of pili from different strains of Moraxella bovis within the same serogroup against infectious bovine keratoconjunctivitis.

Three groups of ten calves were each immunised with a total of 400 micrograms pili prepared from three separate strains of Moraxella bovis in Alhydrogel-oil adjuvant as two divided, equal doses 21 days apart. Groups 1 and 2 each received a monovalent vaccine made from strain 4L and S276R respectively, which belonged to pili serogroup A. Group 3 received vaccine made from pili of strain Maff1, belonging to serogroup F. A further group of ten calves served as non-vaccinated controls. Calves in groups 1 and 2 had developed serogroup A-specific antibody and those in group 3 developed serogroup F-specific antibody, and some evidence of cross-reacting antibody was also detected when measured by an agglutination test using formalin-killed piliated cells of serogroup A strain 4L. Although antibody titres measured against purified pili by ELISA were highest with homologous serogroup antigens, cross-reactive titres to shared epitopes of M. bovis pili were also detected by this method. Ocular challenge of the 40 calves with virulent M. bovis of serogroup A strain S276R was carried out 14 days after the second vaccine dose. All non-vaccinated calves developed infectious bovine keratoconjunctivitis (IBK). The percentage protection in groups 1 (strain 4L) and 2 (strain S276R) was 60% and 80% respectively (P less than 0.05), with mean lesion scores of 0.7 and 0.3 out of a possible 6.0. The percentage protection of calves in group 3 (strain Maff1) was only 30%, with a mean lesion score of 1.4 compared with 2.2 for non-vaccinated controls. The present findings, together with other evidence indicating that immunity to IBK is serogroup-specific, suggest that inclusion of pili from one representative strain from each of the seven Australian and British serogroups in a polyvalent, subunit vaccine should effectively protect the majority of cattle against IBK caused by most field strains of M. bovis encountered in Australia and the United Kingdom.     

Prevalence of serogroups and virulence factors of Escherichia coli strains isolated from pigs with postweaning diarrhoea in eastern China

This study was undertaken to determine the present distribution of serogroups, hemolytic activity and virulence factors among Escherichia coli strains isolated from pigs with postweaning diarrhoea from eight provinces in eastern China. Two hundred and fifteen E. coli isolates were serogrouped with O-antisera, investigated for hemolytic activity, assessed for F4, F5, F6, F18 and F41 fimbrial antigens by monoclonal antibodies and detected for genes of enterotoxins and shiga-toxin-two-variant (Stx2e) by a multiplex polymerase chain reaction (PCR). Among these E. coli isolates, 140 were determined to be placed in serogroups, 52 were unable to be serogrouped and the rest 23 auto-agglutinated. These isolates distributed in 45 serogroups and 64.3% (90/140) belonged to 12 O serogroups: O8, O9, O11, O20, O32, O91, O93, O101, O107, O115, O116 and O131. Hemolytic activity was detected in 11.6% (25/215) of all isolates. Several uncommon O serogroups were discovered in this study. Agglutination tests showed that 50.2% (108/215) of these isolates were positive for one or more of the five fimbrial antigens. Seventy-two E. coli strains expressed single fimbria and 36 strains expressed two or more fimbriae. Among these 215 E. coli isolates, strains expressing F18, F4, F6, F6 + F18 or F5 + F41 occurred more frequently. PCR analysis showed that 60.5% (130/215) of the isolates only harboured the gene of estI (STI) while 6.0% (13/215) strains possessed the genes of stx2e, estI and estII and 5.6% (12/215) of strains had the genes of estI/estII. Of all these isolates, 107 (49.8%) were negative for the fimbrial antigens examined. The fimbria-negative isolates usually possessed genetic determinant of estI (78, 72.9%).     

Biochemical and molecular characterization of minor serogroups of Shiga toxin-producing Escherichia coli isolated from humans in Osaka prefecture

We have investigated 37 minor serogroup Shiga toxin-producing Escherichia coli (STEC) strains other than O157, O26, and O111 isolated from human specimens in Osaka prefecture to determine their serological and biochemical characteristics, virulence-associated genes, and clinical signs in patients. The same serotype strains were genotyped by pulsed-field gel electrophoresis (PFGE). The O antigen of 33 strains were typed into 10 serogroups; O28, O63, O65, O91, O103, O119, O121, O126, O165, and O177, and other 4 strains were not agglutinated with any serum. Four different Shiga toxin (Stx) types (1, 2, 2c, and 2f) were distributed in these isolates. The intimin gene was present in 83.8% of the strains and subtyped into intimin alpha, beta, epsilon, and zeta. STEC O165, O177, and OUT isolated from hemolytic uremic syndrome (HUS) patients revealed atypical biochemical characters; negative reaction for lysine decarboxylase and gas production from glucose. Eleven strains including the isolates from HUS patients generated no colonies on cefixime-tellurite (CT)-sorbitol-MacConkey agar plates, since they showed high sensitivity (MIC 相似文献   

Colonization factor different from K88, K99, F41 and 987P in enterotoxigenic Escherichia coli strains isolated from postweaning diarrhoea in pigs.

A novel common colonization factor was detected in enterotoxigenic strains of Escherichia coli isolated from intestinal contents of piglets affected with postweaning diarrhoea. This factor was antigenically distinct from the previously described K88, K99, F41, 987P, CFAI, CFAII and Att25 fimbrial antigens. E. coli strains possessing this factor adhered to the pig intestinal brush borders and one strain, used in experimental infection in weanlings, colonized the intestinal epithelium and induced diarrhoea. Examination of 212 toxigenic strains of E. coli isolated from weanlings revealed the presence of the novel common colonization factor in 83 strains, belonging to serogroups O25, O108, O138, O141, O147 and O157. The antigen K88 was detected in 47 strains belonging to serogroups O8, O141, O147 and O149.     

Serogroups of Campylobacter fetus and Campylobacter jejuni isolated in cases of ovine abortion

Of 38 aborted ovine fetuses from 23 sheep flocks 29 C. fetus subsp. fetus and 22 C. jejuni were isolated and examined biochemically and serologically for heat-stable antigens. Serologic examinations were carried out by passive haemagglutination test. In case of C. fetus subsp. fetus strains alkaline antigen extraction was used. Antisera to two serogroups of C. fetus and to Penner serotype reference strains 1 to 60 were produced in rabbits. Abortion was caused in 18 (78.3%) flocks by C. fetus subsp. fetus and in 5 (21.7%) flocks by C. jejuni. Six C. fetus subsp. fetus strains grew well at both 43 and 25 degrees C. With one exception all C. fetus subsp. fetus were resistant, whereas all 29 C. fetus subsp. venerealis strains were sensitive to 30 micrograms/ml cefoxitin and cefamandole. These two cephalosporins can be used to differentiate the two subspecies of C. fetus. Passive haemagglutination test using alkaline antigen extraction is a proper method for the examination of heat-stable antigens of both C. fetus subspecies. Out of 24 C. fetus subsp. fetus strains 13 belonged to serogroup A(01), and 11 to serogroup B(02). C. jejuni strains examined belonged to Penner serogroup 1 (6 strains), to serogroup 5 (4 strains) and to serogroup 8 (4 strains).     

Prevalence of F107 fimbriae on Escherichia coli isolated from pigs with oedema disease or postweaning diarrhoea

The study comprises fifty 4 to 12 weeks old pigs that died from oedema disease or severe diarrhoea. Smears were prepared from the mucosa of duodenum, jejunum and ileum, and by immunofluorescence F107 fimbrial antigens were detected. E. coli. strains were isolated from the intestines and were characterised by slide agglutination (serogroup and F107 fimbriae production), by their cytotoxicity for Vero cells, and by gene amplification (genes coding for the major F107 subunit FedA, the toxin causing oedema disease SLT-IIv, and enterotoxins LTI, STIa and STII). F107 fimbriae were demonstrated in association with E. coli of serogroups O139:K12 and O141:K85a,b but not of serogroup O149:K91:F4a,c. Expression in culture of F107 fimbriae by some isolates gave additional evidence for production of these fimbriae by ETEC strains. The genetic determinant of SLT-IIv was found in association with F107, and could not be detected in serogroup O149:K91:F4a,c. Gene fedA was demonstrated in two isolates which were devoid of SLT-IIv. Most isolates from cases of oedema disease belonged to serogroup O139:K12 and did not contain enterotoxin genes. Isolates from pigs that suffered from diarrhoea were serotyped O141:K85a,b or O149:K91:F4a,c, and carried at least two enterotoxin genes in their genomes. In a small proportion of the cases F107 antigens were demonstrated in intestinal smears although gene fedA was not detected in the corresponding isolates. The results confirm the importance of F107 fimbriae as virulence factor in oedema disease E coli strains, but also demonstrate that F107 fimbriae can be found in association with postweaning diarrhoea isolates. In these latter strauns enterotoxins were always demonstrated, irrespective of the presence of toxin SLT-IIv.     

Cross-protective immunity and the serological classification system for Bacteroides nodosus

The relationship between the serological classification system for serogroup B and for serogroup H of Bacteroides nodosus and cross-protection between subgroups within these serogroups was examined. Protection against ovine footrot following vaccination was achieved against other subgroup strains provided sufficient cross-reactive antibody was induced by shared pilus antigens. Within serogroup B, better cross-protection against one subgroup was obtained with a pili vaccine than a whole cell vaccine which correlated with higher pilus antibody titres induced by the former. For serogroup H, a lack of cross-protection and serological reactivity between subgroups was demonstrated, which indicates that the prototype strain of subgroup H2 should be designated a new serogroup.     

Phase variation of pili of Corynebacterium pilosum.

Whether or not (?) phase variation occurs in the pili of Corynebacterium pilosum was biologically examined using the colony enzyme-linked immunosorbent assay (ELISA) blot test with anti-pili immune serum. From the densely piliated clone (35P+) of C. pilosum 35, non-piliated variants were isolated at a frequency of 2.45 x 10(-3). From one of the non-piliated variants (designated as P(-11)/35P+), a piliated variant was isolated at a frequency of 4.68 x 10(-4), one log less frequently than the non-piliated variant. From this piliated variant as designated (P+4/P(-11)/35P+), a non-piliated variant was isolated at a frequency of 3.86 x 10(-3). C. pilosum was thus alternated between piliated and non-piliated at a fairly high frequency, suggesting that the pili may undergo phase variation. This is the first finding of phase variation of the pili of Gram-positive bacteria.     

Pathogenic and fecal Escherichia coil strains from turkeys in a commercial operation

The biochemical phenotypes and antimicrobial susceptibility patterns of 105 clinical Escherichia coli isolates from flocks with colibacillosis in a turkey operation were compared with 1104 fecal E. coli isolates from 20 flocks in that operation. Clinical isolates and 194 fecal isolates with biochemical phenotypes or minimum inhibitory concentrations for gentamicin and sulfamethoxazole similar to clinical isolates were tested for somatic antigens and the potential virulence genes hylE, iss, tsh, and K1. The predominant biochemical phenotype of clinical isolates contained 21 isolates including 14 isolates belonging to serogroup 078 with barely detectable beta-D-glucuronidase activity. Thirty-five fecal isolates had biochemical phenotypes matching common phenotypes of clinical isolates. Sixty-six (63%) clinical isolates exhibited intermediate susceptibility or resistance to gentamicin and sulfamethoxazole compared with 265 (24%) fecal isolates (P < 0.001). Seventy-seven clinical isolates reacted with O-antisera, of which 51 (66%) belonged to the following serogroups: O1, O2, O8, O25, O78, O114, and O119. In comparison, 8 of 35 (23%) fecal isolates subtyped on the basis of biochemical phenotype belonged to these serogroups and four of 167 (2%) fecal isolates subtyped on the basis of their antimicrobial resistance patterns belonged to these serogroups. Iss, K1, and tsh genes were detected more often among clinical isolates than these fecal isolates (P < 0.05). In summary, a small subgroup of E. coli strains caused most colibacillosis infections in this operation. These strains existed at low concentration in normal fecal flora of healthy turkeys in intensively raised flocks. The data suggest that colibacillosis in turkey operations may be due to endogenous infections caused by specialized pathogens.     

Serotyping and virulence genes detection in Escherichia coli isolated from fertile and infertile eggs, dead-in-shell embryos, and chickens with yolk sac infection

Escherichia coli is a common avian pathogen mainly associated with extraintestinal infections such as yolk sac infection (YSI). The aim of this study was to determine the serotypes and the presence of some virulence genes of E. coli strains isolated from different samples in a vertically integrated poultry operation in Mexico. Two hundred sixty-seven E. coli isolates from different samples were serotyped using rabbit serum against the 175 somatic (O) and 56 flagellar (H) antigens of the typing schema. Virulence genes were determined by colony blot hybridization, using DNA probes for st, eae, agg1, agg2, bfp, lt, cdt, slt, and ipaH diarrhea-associated virulence factors. The serogroup of 85% of the strains was determined; O19 (12%), 084 (9%), 08 (6%), and 078 (5%) were the most common. Using the complete antigenic formula (O and H), O19:NM (n = 31) was the serotype most frequently isolated from dead-in-shell embryos and in broilers that had died on the fourth, fifth, sixth, and seventh days after hatch. One hundred ten strains (41.2%) hybridized with one or more of the used probes. Of these, ipaH (72%), eae (30%), and cdt (27%) were the most common. Considering the origin of the respective isolates, 40% of the broiler farm strains were positive for at least one probe. Results show that some avian E. coli strains isolated in Mexico are included in avian pathogenic E. coli serotypes not previously reported, suggesting that they could be specific for this geographic area. The wide distribution of the ipaH gene among nonmotile strains suggests that this invasiveness trait could be important in YSI pathogenesis. On the other hand, some other genes could contribute to E. coli virulence during YSI.     

Occurrence and Characteristics of CS31A Antigen‐Producing Escherichia coli in Calves with Diarrhoea and Septicaemia in Argentina

CS31A is a K88‐related non‐fimbrial adhesin first described on Escherichia coli strains isolated from diarrhoeic and septicaemic calves. In this report, CS31A antigen was screened by immunological methods and confirmed by PCR among bovine E. coli isolates. In addition, CS31A‐producing strains were characterized with respect to different fimbrial antigens, O‐serogroup and other properties related to virulence. Faecal or tissue specimens of 100 diarrhoeic or septicaemic calves and 27 older cattle with different pathologies from 71 outbreaks or individual cases that occurred in Buenos Aires province, Argentina, were examined. CS31A+ E. coli strains were isolated from 21 (21.0%) calves from 16 outbreaks or individual cases. No CS31A+ E. coli was detected in samples from cattle more than 1 year old. Fimbriae F5, F41, F17a and F17b were not detected among the CS31A‐producing strains. Three (14.3%) of the CS31A+ E. coli strains expressed the F17c fimbria. All of the 21 isolates exhibited at least one property of septicaemic strains (resistance to serum, production of aerobactin or colicins) but none of them demonstrated heat‐stable enterotoxigenic activity. CS31A+ E. coli isolates belonged to 10 serogroups, more commonly O8, O7, O17 and O21. The results obtained here confirm the worldwide distribution of CS31A antigen in bovine E. coli strains. However, CS31A+ or CS31A+/F17c+ E. coli were less frequently isolated than they were in North hemisphere countries.     

Serogroups of Campylobacter jejuni from man and animals

A total of 186 campylobacter strains from aborted calf and sheep fetuses, from scouring dogs, rabbits and man, and from retailed poultry were isolated and examined biochemically and serologically for heat stable antigens. Immune sera were produced in rabbits against Penner reference strains from 1 to 60, and against two field isolates. Out of 186 biochemically tested strains 179 (96.2%) proved C. jejuni and only 6 (3.2%) C. coli. One strain has been identified as C. laridis. In cattle and sheep 3.2 and 21.7% respectively of all campylobacter abortions were due to C. jejuni infection. The same agent caused 12.7% of diarrhoea of dogs. The campylobacter infection rate of freshly slaughtered and dressed chicken varied between 25 and 64.3%. Out of the serologically examined 140 C. jejuni strains 118 (84.3%) could be assigned to 16 Penner serogroups and 13 (9.3%) to 2 further serogroups. Serogroups 8 (31.4%), 1 (19.3%) and 2 (12.1%) occurred most frequently. The human isolates represented the widest serotype distribution, as 32 tested strains belonged to 12 serogroups. All those serogroups which caused abortion or diarrhoea in animals or were isolated from poultry carcases were isolated also from man with diarrhoea, but some serogroups were found only in man.     

宠物源大肠杆菌的血清型和毒力基因及耐药性调查

为研究宠物源致病性大肠杆菌(Escherichia coli)的血清型、毒力基因和耐药性之间的相关性,本研究由健康和患病犬、猫直肠拭子样品中分离177株E.coli,并采用玻片凝集法鉴定其血清型,结果显示分离株中定型菌株135株,分别属于20个不同的血清型,其中O1、O2和O8为主要的流行血清型。PCR方法检测11种毒力相关基因,并采用琼脂稀释法测定分离菌株对14种抗菌药的敏感性,结果表明3个血清型的菌株拥有相似的耐药表型,但毒力基因谱不同。62%的分离菌株携带fimH基因,并且毒力基因组合iroN+hlyF、iroN+fimH和traT+sitA比较流行。55%的O1血清型携带fimH基因,并且多数耐受四环素、多西环素、头孢噻吩和庆大霉素;20.8%的O2血清型菌株携带traT和sitA基因;50%的O8血清型携带traT和fimH基因。3个血清型分离菌株多数对安普霉素和阿米卡星敏感。