Prevalence of antimicrobial resistance in enteric Escherichia coli from domestic pets and assessment of associated risk markers using a generalized linear mixed model

Antimicrobial resistance (AMR) is a growing global public health problem, which is caused by the use of antimicrobials in both human and animal medical practice. The objectives of the present cross-sectional study were as follows: (1) to determine the prevalence of resistance in Escherichia coli isolated from the feces of pets from the Porto region of Portugal against 19 antimicrobial agents and (2) to assess the individual, clinical and environmental characteristics associated with each pet as risk markers for the AMR of the E. coli isolates.     

The effect of rehabilitation of northern elephant seals (Mirounga angustirostris) on antimicrobial resistance of commensal Escherichia coli

The aim of this study was to determine if antimicrobial drug use increases resistance of commensal gastrointensinal Escherichia coli of wild northern elephant seals (Mirounga angustirostris) treated in rehabilitation, and, if so, identify the risk factors involved. Minimum inhibitory concentration (MIC) levels of twelve antimicrobial drugs were determined for 289 E. coli isolates from 99 seals sampled at admission and 277 isolates obtained at release from rehabilitation using broth microdilution. Prevalence of E. coli antimicrobial resistance, MIC(50), MIC(90), and clustering of MIC values were determined for seals and the data were analyzed using Fisher's exact test, ordinal logistic regression and negative binomial regression. At release from rehabilitation 77.8% of the seals had antimicrobial resistant E. coli compared to 38.4% of the seals at admission. The MIC(90) for amoxicillin-clavulanic acid, chloramphenicol, enrofloxacin, ticarcillin-clavulanic acid, and trimethoprim-saulfamethoxazole were at levels considered to be sensitive at admission but they increased to levels of resistance at release. E. coli were grouped into four clusters by their MIC values, with increasing levels of resistance going from Cluster 1 to 4. A primary risk factor associated with the probability of a seal having E. coli in Clusters 3 and 4 was time in rehabilitation, regardless of whether the animal received treatment with antimicrobial drugs, suggesting nosocomial infection. The results of this study provide evidence that increased levels of hygiene and appropriate use of antimicrobial therapy might be important in the rehabilitation of wild animals to prevent rise in the prevalence of antimicrobial resistant bacteria.     

Antimicrobial resistance of Escherichia coli isolates from canine urinary tract infections

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 bla_TEM-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.     

一例肉鸡大肠杆菌和粪肠球菌混合感染的诊治

本试验对某发病肉鸡场的病死鸡进行了病原学诊断。通过病原分离、生化试验、动物试验、血清型鉴定、PCR扩增等方法对分离细菌进行了鉴定,最终确定为大肠杆菌和粪肠球菌的混合感染。在此基础上进行了药敏试验,筛选出了大肠杆菌的高敏药物阿米卡星和庆大霉素,而粪肠球菌只对某些氟喹诺酮类药物中度敏感,其余均显示为耐药。将阿米卡星、庆大霉素和恩诺沙星用于发病鸡群的治疗,很快控制了疫情,及时减少了经济损失。     

Effect of susceptibility to enterotoxigenic Escherichia coli F4 and of dietary tryptophan on gut microbiota diversity observed in healthy young pigs

Healthy weaned pigs susceptible to enterotoxigenic Escherichia coli F4 (ETEC) require more tryptophan (Trp) to maximize their performance. This may be related to an effect on intestinal microbiota. We studied the intestinal bacterial diversity of healthy pigs with different susceptibility to ETEC and fed different Trp levels. Thirty-six littermate weaned pigs were selected to obtain a set potentially formed of 50% ETEC-susceptible and 50% non-susceptible pigs, based on a Mucin 4 gene polymorphism. Pigs were fed a diet with 0.17 (TrpL) or 0.22 (TrpH) standardized ileal digestible Trp:Lys ratio for 21 days. Slaughtered pigs were classified into non-susceptible, mildly susceptible, and susceptible, by testing ETEC adhesion to intestinal villi. Bacterial diversity in jejunum content was assessed by the 16S rRNA gene-targeted denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis and expressed by the Shannon index. Susceptible pigs had a reduced bacterial diversity, particularly with TrpL diet (p = 0.003). The ETEC adhesion class affected the quantification of enterobacteria DNA (p = 0.027). One DGGE band, which referred to Clostridium bartlettii, was not evidenced in all the susceptible pigs; less DNA from this microbe was quantified by RT-PCR in the jejunum from TrpH susceptible pigs (p = 0.025) compared to TrpL. The gene expression for β-galactoside α-2,3-sialyltransferase 1 was higher in jejunal tissue of ETEC-susceptible pigs (p = 0.019). In studies on pig gut microbiota, the presence of intestinal receptors for ETEC should be considered because of their contribution to a reduced bacterial diversity. This effect could be partially reversed by dietary Trp addition.     

Distribution of streptogramin resistance genes and genetic relatedness among quinupristin/dalfopristin-resistant Enterococcus faecium recovered from pigs and chickens in Korea

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.     

广东地区猪源大肠杆菌耐药性及其系统发育群的研究简

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。     

Phenotypic and genotypic characteristics of antimicrobial resistant Escherichia coli isolated from symbovine flies, cattle and sympatric insectivorous house martins from a farm in the Czech Republic (2006-2007)

The prevalence of antimicrobial resistant Escherichia coli was tested in symbovine flies and sympatric house martins (Delichon urbica) at a dairy farm. Antimicrobial resistant E. coli was detected in 89% (n = 147) of isolates from flies within a calf barn. Isolates with the same antimicrobial resistance phenotypes, genes, and pulsotypes were found between both fly and calf E. coli isolates, suggesting that the calves were the initial source of the antimicrobial resistant strains in fly isolates. Symbovine flies were considered as important reservoirs of antimicrobial resistant E. coli strains at a dairy farm, due to their intensive contact with cattle feces and manure. House martin fecal samples from the same farm contained 4.5% (n = 393) of antimicrobial resistant E. coli. House martin isolates displayed different macrorestriction profiles than fly isolates and the significance of house martins as a reservoir and vector of antimicrobial resistant E. coli appears low.     

一株猪源屎肠球菌的分离、鉴定及益生功能初步研究

从健康仔猪粪便中分离到一株乳酸菌ZW002,并从形态、生理生化指标,16S rRNA基因序列分析,鉴定该菌株为屎肠球菌(Enterococcus faecium),将其16S rRNA基因提交GenBank,登录号为JN542513。从耐酸、耐胆盐及抑菌性能等方面对菌株进行益生功能初步研究,结果表明,菌株ZW002表现出良好的耐受性及益菌性能,为猪用微生态制剂的研究开发奠定了基础。     

Characterization of integrons in multiple antimicrobial resistant Escherichia coli isolates from bovine endometritis

To assess the prevalence of antimicrobial resistance and three classes of integrons in Escherichia coli (E. coli) strains (n = 57) isolated from bovine endometritis in Inner Mongolia of China, antimicrobial susceptibility and the presence of three types of integrons were characterized. Most isolates were susceptible to ceftiofur, furazolidone, ciprofloxacin and enrofloxacin, while 57 isolates were all resistant to sulfamethoxydiazine and trimethoprim. High resistant incidence rates were exhibited to sulfadiazine, tetracycline, oxytetracycline, cefazolin, chloramphenicol. Forty-six of 57 E. coli strains were resistant to above 10 antibiotics (80.70%). The integrase gene and gene cassettes of integrons were amplified by PCR. DNA sequencing and analysis were used to identify the genetic content of the integron-variable regions. Neither class II nor class III integron was detected, while 36.8% (n = 21) of the isolates were positive for the presence of intI1 gene. Analysis of gene cassettes revealed that six gene cassettes were found, which encoded resistance to trimethoprim (dhfr, dhfrI, dfrA17) and aminoglycosides (aadA1, aadA2, aadA5). Among them, the gene cassette array dfrA17–aadA5 was found most prevalent (66.7%). The resistance profile of positive-integron isolates was relatively broad and they were resistant to more than eight antimicrobials (n ? 8). The correlation analysis revealed the incidence of integrons among the isolates were related to the multiple antibiotic resistance profile, indicating integrons play an important role in the dissemination and spread of the antimicrobial resistant strains.     

Genomic Description of Antibiotic Resistance in Escherichia coli and Enterococci Isolates from Healthy Lusitano Horses

Antibiotic resistance is a global problem, and it is known that commensal bacteria can act as reservoir of antibiotic resistance genes of clinical importance. The aim of the present study was to determine the antibiotic resistance phenotype and mechanisms implicated in resistance of Escherichia coli and Enterococcus spp. isolates collected from fecal samples of 90 Lusitano horses from Portugal. Sixteen of the 71 E. coli isolates (22.5%) recovered showed resistance to at least one of the antibiotics tested. The number of E. coli isolates resistant to streptomycin, tetracycline, chloramphenicol, ampicillin, trimethoprim-sulfamethoxazole, and gentamicin was 9, 7, 6, 3, 2, and 1, respectively. The bla_TEM-1 and bla_OXA-1 genes were detected in ampicillin-resistant isolates and the sul2 and dfrA1 genes in trimethoprim-sulfamethoxazole-resistant, while the aac(3)-I, floR and tet(A) were found in the gentamicin, chloramphenicol and tetracycline-resistant isolates, respectively. Twenty-two of the 71 (31%) recovered enterococci showed antibiotic resistance for at least one of the tested antibiotics, and resistant isolates were identified as Enterococcus faecium (n = 14), E. faecalis (n = 3), E. hirae (n = 2), and Enterococcus spp. (n = 3). The erm(B) and erm(C) genes were identified in erythromycin-resistant enterococci and the tet(M) and/or tet(L) genes in tetracycline-resistant isolates. The slight prevalence of antibiotic resistance among commensal bacteria of healthy Lusitano horses can improve the treatment of upcoming infections in these horses because these microorganisms can be considered as antimicrobial indicator bacteria.     

广东地区猪链球菌的耐药性特点及四环素耐药基因携带情况

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。     

屎肠球菌T013复合制剂饲喂生长猪的效果研究

试验旨在研究日粮中添加屎肠球菌T013复合制剂对生长猪的生产性能、粪便微生物、环境指标及血清指标的影响。选用体重在(31.75±3.78)kg的杜×长×大三元杂交仔猪120头,随机分成对照组(基础日粮)、试验Ⅰ组(基础日粮中添加3%屎肠球菌T013复合制剂)和试验Ⅱ组(基础日粮中添加6%屎肠球菌T013复合制剂),每组4个重复,每个重复10头猪,试验期为28 d。结果表明,屎肠球菌T013复合制剂能增加生长猪日采食量和日增重,降低料重比,但差异不显著(P＞0.05),并且能显著减少腹泻率(P＜0.05);试验Ⅱ组能够极显著降低粪便pH和减少大肠杆菌数量,增加乳酸菌数量(P＜0.01);试验组均能够极显著的减少NH₃的排放(P＜0.01);试验Ⅱ组能够显著增加血清IgG含量和减少尿素氮含量(P＜0.05),对总蛋白、白蛋白、白蛋白/球蛋白和葡萄糖的含量无显著影响(P＞0.05)。因此,屎肠球菌T013复合制剂能够降低生长猪的腹泻率,改善肠道微生态环境,减少NH₃ 的排放,增强猪的免疫能力。     

Avian colibacillosis caused by an intestinal pathogenic Escherichia coli isolate from calf diarrhea

An intestinal pathogenic Escherichia coli isolate from calf diarrhea, containing the iutA, f17A, afa-8D, and cnf2 genes, was able to cause avian colibacillosis after experimental infection in chickens. Intra-tracheal inoculation and spray of this strain caused 10% of mortality and gross lesions, including airsacculitis, pericarditis, and perihepatitis. These results suggest that some bovine pathogenic E. coli can cause extra-intestinal infections in other animal species.     

2022年北京市宠物源细菌耐药性监测浅析

为了解北京市宠物源细菌的抗菌药物耐药情况,2022年,笔者对北京市四个城区的四家宠物医院的犬、猫共计50份样本的肛拭子进行了研究。试验对样品中的大肠杆菌和肠球菌首先进行了分离培养和质谱鉴定,然后采用微量肉汤稀释法分析分离菌株的耐药表型。结果共分离出大肠杆菌25株、肠球菌25株（屎肠球菌14株、粪肠球菌11株）。大肠杆菌耐药率最高的2种抗菌药为四环素和氨苄西林,多重耐药菌占44%;肠球菌耐药情况较严重,粪肠球菌耐药率最高的抗菌药物为磺胺异噁唑,屎肠球菌耐药率最高的抗菌药物为磺胺异噁唑、头孢西丁和红霉素,二者多重耐药菌占分离株总数的100%。综上,北京地区宠物源大肠杆菌、肠球菌的耐药情况较为严峻,且多重耐药现象突出,需要加强对宠物抗菌药使用的监督与管理。     

A longitudinal field trial assesing the impact of feeding waste milk containing antibiotic residues on the prevalence of ESBL-producing Escherichia coli in calves

A longitudinal field trial was carried out on a farm known to harbour cefotaximase (CTX-M)-positive Escherichia coli, in order to assess the impact of feeding waste milk containing antibiotic residues (WM + AR) on the prevalence of these bacteria in the faeces of calves. Fifty calves were alternately assigned to one of two groups at birth and fed either milk replacer (control group) or WM + AR (treatment group). Faecal samples were collected from all calves daily for the first week after enrolment, twice weekly until weaning, then weekly for a further six weeks. Environmental samples from the calf housing were collected weekly. WM + AR and powdered milk samples were examined for antibiotic residues and CTX-M-positive E. coli. Total E. coli and CTX-M-positive E. coli in faecal samples were enumerated using selective media. Regression analyses were performed on the bacterial count data using a population-averaged approach based on generalised estimating equations (GEE) to account for repeated measurements on individual calves over time.     

Gene markers of generic Escherichia coli associated with colonization and persistence of Escherichia coli O157 in cattle

Enterohemorrhagic Escherichia coli (EHEC) O157 are important foodborne pathogens whose major reservoir are asymptomatic cattle. There is evidence suggesting that nonpathogenic E. coli and bacteriophages in the gastro-intestinal tract can influence the pathogenicity of EHEC O157. The factors contributing to the onset and persistence of shedding EHEC O157 in cattle are not completely elucidated. This study used Bayesian network analysis to identify genetic markers of generic E. coli associated with shedding of EHEC O157 in cattle from data generated during an oral experimental challenge study in 4 groups of 6 steers inoculated with three different EHEC O157 strains. The quantification of these associations was accomplished using mixed effects logistic regression. The results showed that the concurrent presence of generic E. coli carrying the prophage marker R4-N and the virulence marker stx2 increased the odds of the onset of EHEC O157 shedding. The presence of prophage markers z2322 and X011C increased, while C1.N decreased the odds of shedding EHEC O157 two days later. A significant antagonist interaction effect between the presence of the virulence marker stx2 on the day of shedding EHEC O157 and two days before shedding was also found. In terms of the persistence of EHEC O157 shedding, the presence of prophage marker R4-N (OR = 16, and 95% confidence interval (CI): 1.1, 252) was found to increase the odds of stopping EHEC O157 shedding, whereas prophage marker C1.N (OR = 0.16, CI: 0.03, 0.7) and the enterohemolysin gene hly (OR = 0.03, CI: 0.001, 0.8) were found to significantly decrease the odds of stopping EHEC O157 shedding. In conclusion, the study found that the presence of certain genetic markers in the generic E. coli genome can influence the pathogenicity of EHEC O157.