Cases Of Colibacillosis Research Articles

Longitudinal study of avian pathogenic Escherichia coli (APEC) serogroups associated with disease in Georgia poultry using molecular serology and virulence gene analysis

ABSTRACT Avian pathogenic Escherichia coli (APEC) is a significant cause of morbidity, mortality, and production loss to the poultry industry worldwide. Here, we characterized 569 E. coli isolates from avian-diagnosed colibacillosis cases from the state of Georgia, USA. In total, 339 isolates were assigned into 32 serogroups with the majority classifying as O78, O2, O25, O8, O1, O86, O18, and O15. Serogroup O25 was found to link with broilers, while broiler breeders were more often associated with serogroup O1 and pet/ hobby birds with serogroup O8. In addition, some serogroups (O1) were more prevalent in the summer and fall. Analysis for virulence-associated genes (VAGs) found 23.20% of isolates did not harbour any genes linked with the APEC pathotype, while ColV plasmid-associated genes (iroN, ompT, hlyF, iss, and aerJ) were frequently detected among most isolates (with 80–96% prevalence) and some of these genes were linked with serogroup. Phylogenetic analysis, classified isolates into phylogenetic groups B2 (34%), F (19%), A (15%), and G (9%). The phylogenetic group B2 isolates also harboured the highest number of VAGs. This study highlights that the current APEC-causing disease in birds in the State of Georgia has identified several emerging serogroups possessing several VAGs that could potentially lead to challenges in colibacillosis control. RESEARCH HIGHLIGHTS Several emerging APEC serogroups were observed in Georgia poultry populations. An association between APEC serogroups and bird type was observed. The prevalence of different APEC serogroups was influenced by season. A multiplex PCR assay targeting common serogroups of APEC in Georgia poultry was developed.

Evaluating the effects of virulence genotype, swarming motility, and multi-locus sequence types of Escherichia coli on layer chicken embryos.

To determine the effects of swarming motility (SM) and multi-locus sequence types (MLST) on the main effect of virulence genotype of Escherichia coli through an embryos lethality assay between the 12th and 18th days of incubation. We collected 58 E. coli isolates from asymptomatic commercial hens (n=42) and lesions of colibacillosis cases (n=16), then classified their virulence genotype as avirulent, moderately virulent, virulent-healthy, and virulent-colibacillosis categories by the presence of five virulence-associated genes (iroN, ompT, hlyF, iutA, and iss). These isolates were further classified as non-motile, motile, or hyper-motile by SM assay. From the 58 isolates, we selected 29 for ELA and determined their MLST. Each isolate was inoculated into 15 embryonated eggs through the allantoic cavity. We found the avirulent isolates reduced the relative embryo weight compared to virulent-colibacillosis and moderately virulent isolates (37.49vs. 41.51 and 40.34%, P=0.03). Among the moderately virulent and virulent-colibacillosis categories, embryo lethality was lower when isolates were non-motile. Yolk retention was unaffected by virulence categories, motility, or MLST. Interaction between virulence genotype and SM substantially influenced the embryo lethality assay of E. coli isolates.

Vaccinating parent flocks against colibacillosis reduces broiler mortality – A retrospective observational study from 2016 to 2019 in Finland

Colibacillosis is one of the most important infectious diseases in modern poultry production. The complex nature of colibacillosis has made it challenging to produce an effective vaccine. As a control measure for colibacillosis outbreak in Finland, a vaccination program with a commercial colibacillosis vaccine and later also an autogenous vaccine was started for parent flocks in 2017. In this retrospective observational study from years 2016–2019, we evaluated first week and total mortality of broiler flocks (n= 6969) originating from parents with different colibacillosis vaccination status. Broiler flocks were divided into three groups according to vaccination status of their parent flocks. First group were flocks from parents with no colibacillosis vaccines; second group was flocks from parents vaccinated with commercial vaccine only; and third group was flocks from parents with both commercial and autogenous vaccine. Bayesian modelling was used to predict posterior distributions of first week mortality and total mortality of the broiler flocks. Results of the modelling revealed that broiler flocks from unvaccinated parents had the highest mortality rates (mean first week mortality 1.40 % and mean total mortality 4.33 %, respectively) whereas flocks from parents with a combination of commercial and autogenous vaccinations had the lowest mortality rates (mean first week mortality 0,91 % and mean total mortality 3,14 %). The mortalities from broilers flocks from parents with only commercial vaccine fell in between these groups. Also, standard deviations of mortality rates were lower in broilers from parents with commercial or both vaccines. This demonstrates that in addition to lowering the mean mortality rates, the vaccinations made high mortality broiler flocks less common. Best performance was obtained when autogenous vaccine was combined to the commercial vaccine. The autogenous vaccine consists of the same type of Escherichia coli strain that was causing most colibacillosis cases during the study period in Finland. This study adds to the evidence of benefits of colibacillosis vaccines during outbreaks. It also demonstrates the importance of the knowledge of the types of APEC strains causing outbreaks to produce effective autogenous vaccines.

Antimicrobial resistance of avian pathogenic Escherichia coli isolated from broiler, layer, and breeder chickens.

Antimicrobials are extensively used in poultry production for growth promotion as well as for the treatment and control of diseases, including avian pathogenic Escherichia coli (APEC). Poor selection, overuse, and misuse of antimicrobial agents may promote the emergence and dissemination of antimicrobial resistance (AMR) in APEC. This study aimed to assess antimicrobial susceptibility patterns and detect antibiotic resistance genes (ARGs) in APEC isolated from clinical cases of colibacillosis in commercial broiler, layer, and breeder chickens. A total of 487 APEC were isolated from 539 across 300 poultry farms in various regions of Nepal. Antimicrobial susceptibility patterns was determined using the Kirby-Bauer disk diffusion and broth microdilution methods. The index of AMR, such as multiple antibiotic resistance (MAR) index, resistance score (R-score), and multidrug resistance (MDR) profile, were determined. Polymerase chain reaction was employed to detect multiple ARGs and correlations between phenotypic and genotypic resistance were analyzed. The prevalence of APEC was 91% (487/539). All of these isolates were found resistant to at least one antimicrobial agent, and 41.7% of the isolates were resistant against 8-9 different antimicrobials. The antibiogram of APEC isolates overall showed the highest resistance against ampicillin (99.4%), whereas the highest intermediate resistance was observed in enrofloxacin (92%). The MAR index and R-score showed significant differences between broiler and layers, as well as between broiler breeder and layers. The number of isolates that were resistant to at least one agent in three or more antimicrobial categories tested was 446 (91.6%) and were classified as MDR-positive isolates. The ARGs were identified in 439 (90.1%) APEC isolates, including the most detected mobilized colistin resistance (mcr1) which was detected in the highest (52.6%) isolates. Overall, resistance gene of beta-lactam (blaTEM), mcr1, resistance gene of sulphonamide (sul1) and resistance gene of tetracycline (tetB) (in broiler), were detected in significantly higher than other tested genes (p < 0.001). When examining the pair-wise correlations, a significant phenotype-phenotype correlation (p < 0.001) was observed between levofloxacin and ciprofloxacin, chloramphenicol and tetracycline with doxycycline. Similarly, a significant phenotype-genotype correlation (p < 0.001) was observed between chloramphenicol and the tetB, and colistin with blaTEM and resistance gene of quinolone (qnrA). In this study, the current state of APEC AMR in commercial chickens is revealed for the first time in Nepal. We deciphered the complex nature of AMR in APEC populations. This information of molecular surveillance is useful to combat AMR in APEC and to contribute to manage APEC associated diseases and develop policies and guidelines to enhance the commercial chicken production.

Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry.

Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC50 and MIC90 of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 108 and 106 CFU/mL. At the cell density of 108 CFU/mL, MIC50 and MIC90 were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 106 CFU/mL, MIC50 and MIC90 were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC50 and MIC90 for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.

Whole Genome Sequencing of Avian Pathogenic Escherichia coli Causing Bacterial Chondronecrosis and Osteomyelitis in Australian Poultry.

Bacterial chondronecrosis with osteomyelitis (BCO) impacts animal welfare and productivity in the poultry industry worldwide, yet it has an understudied pathogenesis. While Avian Pathogenic Escherichia coli (APEC) are known to be one of the main causes, there is a lack of whole genome sequence data, with only a few BCO-associated APEC (APECBCO) genomes available in public databases. In this study, we conducted an analysis of 205 APECBCO genome sequences to generate new baseline phylogenomic knowledge regarding the diversity of E. coli sequence types and the presence of virulence associated genes (VAGs). Our findings revealed the following: (i) APECBCO are phylogenetically and genotypically similar to APEC that cause colibacillosis (APECcolibac), with globally disseminated APEC sequence types ST117, ST57, ST69, and ST95 being predominate; (ii) APECBCO are frequent carriers of ColV-like plasmids that carry a similar set of VAGs as those found in APECcolibac. Additionally, we performed genomic comparisons, including a genome-wide association study, with a complementary collection of geotemporally-matched genomes of APEC from multiple cases of colibacillosis (APECcolibac). Our genome-wide association study found no evidence of novel virulence loci unique to APECBCO. Overall, our data indicate that APECBCO and APECcolibac are not distinct subpopulations of APEC. Our publication of these genomes substantially increases the available collection of APECBCO genomes and provides insights for the management and treatment strategies of lameness in poultry.

Distribution pattern of antibiotic resistance genes in Escherichia coli isolated from colibacillosis cases in broiler farms of Egypt.

Multidrug resistance (MDR) of Escherichia coli has become an increasing concern in poultry farming worldwide. However, E. coli can accumulate resistance genes through gene transfer. The most problematic resistance mechanism in E. coli is the acquisition of genes encoding broad-spectrum β-lactamases, known as extended-spectrum β-lactamases, that confer resistance to broad-spectrum cephalosporins. Plasmid-mediated quinolone resistance genes (conferring resistance to quinolones) and mcr-1 genes (conferring resistance to colistin) also contribute to antimicrobial resistance. This study aimed to investigate the prevalence of antimicrobial susceptibility and to detect β-lactamase and colistin resistance genes of E. coli isolated from broiler farms in Egypt. Samples from 938 broiler farms were bacteriologically examined for E. coli isolation. The antimicrobial resistance profile was evaluated using disk diffusion, and several resistance genes were investigated through polymerase chain reaction amplification. Escherichia coli was isolated and identified from 675/938 farms (72%) from the pooled internal organs (liver, heart, lung, spleen, and yolk) of broilers. Escherichia coli isolates from the most recent 3 years (2018-2020) were serotyped into 13 serotypes; the most prevalent serotype was O125 (n = 8). The highest phenotypic antibiotic resistance profiles during this period were against ampicillin, penicillin, tetracycline, and nalidixic acid. Escherichia coli was sensitive to clinically relevant antibiotics. Twenty-eight selected isolates from the most recent 3 years (2018-2020) were found to have MDR, where the prevalence of the antibiotic resistance genes ctx, tem, and shv was 46% and that of mcr-1 was 64%. Integrons were found in 93% of the isolates. The study showed a high prevalence of E. coli infection in broiler farms associated with MDR, which has a high public health significance because of its zoonotic relevance. These results strengthen the application of continuous surveillance programs.

Nebulization as a more efficient method than atomizer for experimental reproduction of avian colibacillosis in young chickens

ABSTRACT Infection and immunity studies involving genetically modified organisms (GMOs), such as gene knockout bacterial mutants require stringent physical containment to prevent the accidental spread of these organisms into the environment. Experimental respiratory tract infection models often require the animals, for example birds, to be transported several times between a negative pressure housing isolator and a bespoke aerosol exposure chamber under positive pressure. While the exposure chamber is sealed and fitted with HEPA filters, the repeated movements of infected animals and opening of the chamber can still pose a serious risk of breaching containment of the organism in the experimental facility. In the current study, the ability of two aerosol infection protocols that expose birds to avian pathogenic E. coli (APEC) aerosols directly within the housing isolator was evaluated. Young chicks were exposed to APEC E956 within the negative pressure housing isolators using either a nebulizer or an atomizer. Birds exposed twice (days 1 and 4) to aerosols of APEC E956 produced by the nebulizer developed a rapidly progressing disease mimicking field cases of avian colibacillosis. However, birds exposed to aerosols of APEC E956 produced by an atomizer, did not develop colibacillosis even after 3 exposures to APEC E956 on days 1, 4 and 7. Consequently, the current study reports the nebulizer was more efficacious in producing avian colibacillosis under stricter bacterial containment settings.

Description and validation of a new set of PCR markers predictive of avian pathogenic Escherichia coli virulence

Avian colibacillosis is the main bacterial infectious disease in poultry and is caused by avian pathogenic Escherichia coli (APEC). However, E. coli strains are very diverse, and not all are pathogenic for poultry. A straightforward scheme for identifying APEC is crucial to better control avian colibacillosis. In this study, we combined high-throughput PCR and a machine learning procedure to identify relevant genetic markers associated with APEC. Markers related to phylogroup, serotype and 66 virulence factors were tested on a large number of E. coli strains isolated from environmental, faecal or colibacillosis lesion samples in 80 broiler flocks. Nine classification methods and a machine learning procedure were used to differentiate 170 strains presumed non-virulent (obtained from farm environments) from 203 strains presumed virulent (obtained from colibacillosis cases on chicken farms) and to develop a prediction model to evaluate the pathogenicity of isolates. The model was then validated on 14 isolates using a chick embryo lethality assay. The selected and validated model based on the bootstrap aggregating tree method relied on a scheme of 13 positive or negative markers associated with phylogroups (arpA), H4 antigen and virulence markers (aec4, ETT2.2, frzorf4,fyuA, iha, ireA, iroN, iutA1, papA, tsh, and vat). It had a specificity of 84 % and a sensitivity of 85 %, and was implemented as an online tool. Our scheme offers an easy evaluation of the virulence of avian E. coli isolates on the basis of the presence/absence of these 13 genetic markers, allowing for better control of avian colibacillosis.

Molecular and Serological Characteristics of Avian Pathogenic Escherichia coli Isolated from Various Clinical Cases of Poultry Colibacillosis in Poland.

Simple SummaryInfections caused by avian pathogenic Escherichia coli (APEC) represent a serious threat for poultry production and economic losses. These bacteria have a number of mechanisms that enable them to colonize various ecosystems. We analyzed E. coli from chicken and turkey broilers, laying hens, and broiler parents. In this work, we characterized virulence factors in APEC isolated from poultry in Poland. We also attempted to show a correlation between lesion severity, the presence of virulence genes, and the E. coli serogroup. The most prevalent serotype among E. coli isolates from all types of chickens was serotype O78, in contrast to isolates from turkeys, in which the prevalence of four serotypes, O1, O2, O18, and O78, was similar. Once the serotype was distinguished, it was possible to assign certain virulence characteristics to the isolate and to associate it with the symptoms present, as well as to track the frequency of occurrence. All of the eight virulence genes analyzed were most common in cases with severe, generalized disease processes. The results also confirmed that there is a great variety of APEC strains in the poultry population.Escherichia coli infections are a major problem in modern poultry production. Avian pathogenic E. coli (APEC) strains have several mechanisms that enable them to colonize various ecosystems. In this study, 290 E. coli isolates were recovered from clinical cases of colibacillosis in chicken and turkey broilers and from laying and breeding hens. The samples were taken from organs with pathological changes suggesting colibacillosis. The lesions were assigned to three groups depending on their advancement, of which the largest (60% of the isolates) was group 3, with the most extensive changes. The most common serotype was shown to be O78 (14%). The most frequently detected gene among those tested was iss, while papC was the least prevalent. An analysis of the number of genes present per isolate revealed that the presence of four genes was the most common (22%), while only 1% of the strains tested had all eight genes. The most frequently detected genes for each serotype were iss and iucD for O78; irp2 and cvi/cva for O1; irp2, iucD, and iss for O2, and iss and iucD for O8, for which the least frequent was papC. All O18 serotype strains had the iss gene, while none had the vat gene.

Antibiotic susceptibility, serotyping and pathogenicity determination of Avian Escherichia coli isolated from Colibacillosis cases in broiler chicken in Aljabel Alakhdar Region, Libya

Antibiotic susceptibility, serotyping and pathogenicity determination of Avian Escherichia coli isolated from Colibacillosis cases in broiler chicken in Aljabel Alakhdar Region, Libya

Molecular and phenotypic characterization of avian pathogenic Escherichia coli isolated from commercial broilers and native chickens

Many studies have examined avian pathogenic Escherichia coli (APEC) from commercial broilers but few have examined isolates from native chickens. This study compared APEC isolates from commercial broilers and native chickens in regard to the phylogenetic group and the phenotypic and genotypic antimicrobial resistance profiles. From 100 suspect colibacillosis cases in both commercial broilers and native chickens, a total of 90 broiler isolates and 42 native chicken isolates were identified as E. coli by biochemical tests. Phylogenetic grouping revealed that 90 broiler APEC isolates belonged to A group (5.56%), B1 group (22.22%), B2 group (31.11%), and D group (41.11%). The 42 native chicken APEC isolates belonged to A group (35.71%), B1 group (26.19%), B2 group (30.95%), and D group (7.14%). The difference in the allocation to groups A and D of the 2 isolate types was significant (P < 0.05). The APEC broiler isolates had a significantly higher multidrug-resistant (MDR) rate (80%) than the native chicken isolates (14.29%) (P < 0.05). The APEC broiler isolates demonstrated significantly higher resistance rates than the native chicken isolates for amoxicillin (98.89%; 78.57% respectively), chloramphenicol (42.2%; 9.5%), enrofloxacin (68.9%; 7.1%), gentamicin (11.1%; 0%), nalidixic acid (72.2%; 7.1%), sulfamethoxazole + trimethoprim (45.6%; 2.4%), and tetracycline (88.9%; 76.2%) (P < 0.05). The APEC broiler isolates had a significantly higher presence compared with the native chicken isolates of the following resistance genes:- by blaTEM (43.3%; 21.4%, respectively), cml-A (34.4%; 2.4%), tetA (76.7%; 40.5%), tetB (26.7%; 0%), sul2 (23.3%; 14.3%), and dhfrI (13.3%; 0%) (P < 0.05). The qnrB and qnrS genes were detected (12.16%; 72.97% respectively), in the APEC broiler isolates resistant to nalidixic acid and/or enrofloxacin while only qnrS genes was detected in all 3 APEC native chicken isolates. Regarding the point mutations of gyrA and parC, all isolates were positive to gyrA83S, gyrA87D, gyrA87L, gyrA87NY, parC80S and parC80I except that gyrA83S was not present in 20 APEC broiler isolates. Antimicrobial stewardship programs should be targeted at the backyard poultry sector as well as the commercial poultry sector.

Detection of virulence genes of APEC (avian pathogenic Escherichia coli) isolated from poultry in Noakhali, Bangladesh

Avian colibacillosis, caused by avian pathogenic Escherichia coli (APEC), is one of the major infectious diseases of poultry that bring about great economic loss for the Bangladesh poultry industry. The present study aimed to determine the virulence genes of avian pathogenic Escherichia coli (APEC) from cases of colibacillosis in poultry at the Noakhali district of Bangladesh. Currently, virulence-associated gene profiles of APEC isolates were investigated by polymerase chain reaction (PCR). A total of 24 (twenty-four) Escherichia coli isolates were collected and presumptively identified from 8 (eight) colibacillosis cases from 4 commercial broiler poultry farms (2 broilers per farm) in Noakhali, Bangladesh. The pathogenesis of Escherichia coli involves a wide range of different virulence genes. At this point, four virulence genes, iutA, hlyF, iroN, and iss were detected by PCR analysis. It has been observed that iutA, iss, hlyF, and iroN genes were found in 7(29.16%), 20(83.33%), 22(91.66%), and 24(100%) APEC isolates respectively. Furthermore, out of the twenty-four APEC isolates, six (25%) isolates had four virulence genes, fourteen (58.33%) isolates carried at least three virulence genes, three (12.5%) isolates carried two genes and one (4.16%) isolates had one virulence gene. Most importantly. six types of virulence gene profiles existed within the APEC isolates from which profile number 3 (hlyF, iroN, iss) having 13 (54.16%) isolates were predominant. The occurrence of APEC isolates of this region which is responsible for avian colibacillosis cases can be a matter of concern from the public health point of view. Future investigations will be able to utilize these virulence genes to identify APEC in Bangladesh helping in the diagnosis and prevention of colibacillosis in poultry.&#x0D; Bioresearch Commu. 7(1): 967-972, 2021 (January)

Characterizing avian pathogenic Escherichia coli (APEC) from colibacillosis cases, 2018.

Colibacillosis caused by avian pathogenic Escherichia coli (APEC) is a devastating disease of poultry that results in multi-million-dollar losses annually to the poultry industry. Disease syndromes associated with APEC includes colisepticemia, cellulitis, air sac disease, peritonitis, salpingitis, omphalitis, and osteomyelitis among others. A total of 61 APEC isolates collected during the Fall of 2018 (Aug–Dec) from submitted diagnostic cases of poultry diagnosed with colibacillosis were assessed for the presence of 44 virulence-associated genes, 24 antimicrobial resistance genes and 17 plasmid replicon types. Each isolate was also screened for its ability to form biofilm using the crystal violet assay and antimicrobial susceptibility to 14 antimicrobials using the NARMS panel. Overall, the prevalence of virulence genes ranged from 1.6% to >90% with almost all strains harboring genes that are associated with the ColV plasmid—the defining trait of the APEC pathotype. Overall, 58 strains were able to form biofilms and only three strains formed negligible biofilms. Forty isolates displayed resistance to antimicrobials of the NARMS panel ranging from one to nine agents. This study highlights that current APEC causing disease in poultry possess virulence and resistance traits and form biofilms which could potentially lead to challenges in colibacillosis control.

Bacteriophage activity against and characterisation of avian pathogenic Escherichia coli isolated from colibacillosis cases in Uganda.

Avian Pathogenic Escherichia coli (APEC) cause colibacillosis leading to significant economic losses in the poultry industry. This laboratory-based study aimed at establishing stocks of avian pathogenic Escherichia coli lytic bacteriophages, for future development of cocktail products for colibacillosis management. The study determined the antibiotic susceptibility; phylogenetic categories, occurrence of selected serotypes and virulence genes among Escherichia coli stock isolates from chicken colibacillosis cases; and evaluated bacteriophage activity against the bacteria. Escherichia coli characterization was done through phenotypic and multiplex PCR methods. Bacteriophage isolation and preliminary characterization was achieved using the spot assay and overlay plating techniques. Fifty-six (56) isolates were phenotypically confirmed as E. coli and all exhibited resistance to at least one antimicrobial agent; while multi-drug resistance (at least three drugs) was encountered in 50 (89.3%) isolates. The APEC isolates mainly belonged to phylogroups A and D, representing 44.6% and 39.3%, respectively; whereas serotypes O1, O2 and O78 were not detected. Of the 56 isolates, 69.6% harbored at least one virulence gene, while 50% had at least four virulence genes; hence confirmed as APEC. Virulence genes, ompT and iutA were the most frequent in 33 (58.9%) and 32 (57.1%) isolates respectively; while iroN least occurred in 23 (41.1%) isolates. Seven lytic bacteriophages were isolated and their host range, at 1×108 PFU/ml, varied from 1.8% to 17.9% of the 56 APEC isolates, while the combined lytic spectrum was 25%. Phage stability was negatively affected by increasing temperatures with both UPEC04 and UPEC10 phages being undetectable at 70°C; whereas activity was detected between pH 2 and 12. The high occurrence of APEC isolates resistant against the commonly used antibiotics supports the need for alternative strategies of bacterial infections control in poultry. The low host range exhibited by the phages necessitates search for more candidates before in-depth phage characterization and application.

Diversity of Escherichia coli strains isolated from day-old broiler chicks, their environment and colibacillosis lesions in 80 flocks in France

Avian colibacillosis is the most common bacterial disease affecting broilers. To better evaluate the diversity and the origin of the causative Escherichia coli strains infecting birds, we conducted a study on 80 broiler flocks. Just before the arrival of chicks on the farm, samples were collected in the farm environment (walls, feeders, air inlets, etc.) and, upon delivery, day-old chicks (DOCs) and the transport boxes were also sampled. Isolates were obtained from these samples, and from organs of chickens exhibiting typical colibacillosis symptoms. The isolates were characterized using high-throughput qPCR to detect a range of genetic markers (phylogroups, main serogroups virulence markers, etc.). A total of 967 isolates were studied, including 203 from 28 colibacillosis episodes, 484 from DOCs, 162 from transport boxes and 118 from the farm environment. These isolates yielded 416 different genetic profiles, of which 267 were detected in single isolates, and the others were observed in up to 44 isolates from nine farms. The distributions of isolates across phylogroups and the main serogroups varied with the origin of isolation. The isolates obtained from colibacillosis cases either shared a single genetic profile or were different. In a few cases, we observed the same profile for isolates obtained from DOCs and colibacillosis lesions in the same flock or different flocks. However, some flocks receiving DOCs contaminated with isolates bearing the genetic profile of colibacillosis cases identified in other flocks remained healthy. This study highlights the huge diversity among avian E. coli isolated from diseased and non diseased birds.

Pathogenicity of Shiga Toxin Type 2e Escherichia coli in Pig Colibacillosis.

Shiga toxin type 2e (Stx2e) Escherichia coli is the causative factor of diarrhea and edema in swine. The aims of this study were to determine the prevalence of Stx2e-producing E. coli isolates and to characterize isolates from clinical cases of pig colibacillosis and healthy swine. During the 11 years of the study (2006–2017), a total of 233 Stx2e-producing isolates were detected−230 out of 2,060 (11.16%) E. coli isolated from diseased pigs and 3 out of 171 (1.75%) from healthy swine. Stx2e-producing isolates were indeed more present in clinical colibacillosis cases than in healthy pigs (p = 0.0002). The predominant serogroup was O139 (79.82%) and the most common fimbrial factor present in these isolates was F18 (177 isolates), followed by F6 (5 isolates). The enterotoxins LTI, STa, and STb were detected in 10.43, 41.73, and 48.26% of the isolates, respectively. The predominant virotypes F18-Stx2e and -STa-STb-Stx2e were similarly present in weaners (33.33 and 35.52%) and finishers (38.30 and 25.53%). Among isolates from diseased pigs, O139 and F18 were the more frequently identified serogroup and virulence factor, respectively. Of the tested 230 Stx2e-producing isolates isolated from diseased pigs, 29 (12.60%) harbored genes encoding ESBL, particularly TEM (79.30%), CTX-M1 (17.20%), and CMY-2 (3.40%). Antimicrobial resistance to tetracycline was the most common characteristic (98.25%), followed by ampicillin (93.91%), cephalotin (90.43%) and trimethoprim/sulfamethoxazole (82.17%). Our results showed that Stx2e-producing E. coli were more frequently associated with clinical forms of colibacillosis, with minimal probability to isolate these isolates from healthy pigs.

Resistance to extended-spectrum cephalosporins in Escherichia coli and other Enterobacterales from Canadian turkeys.

The goal of this study was to determine the frequency of resistance to extended-spectrum cephalosporins (ESCs) in Escherichia coli and other Enterobacterales from turkeys in Canada and characterize the associated resistance determinants. Pooled fecal samples were collected in 77 turkey farms across British Columbia, Québec, and Ontario. Isolates were obtained with and without selective enrichment cultures and compared to isolates from diagnostic submissions of suspected colibacillosis cases in Ontario. Isolates were identified using MALDI-TOF and susceptibility to ESCs was assessed by disk diffusion. The presence of blaCMY, blaCTX-M, blaTEM, and blaSHV was tested by PCR. Transformation experiments were used to characterize blaCMY plasmids. Genome sequencing with short and long reads was performed on a representative sample of blaCTX-M-positive isolates to assess isolates relatedness and characterize blaCTX-M plasmids. For the positive enrichment cultures (67% of total samples), 93% (587/610) were identified as E. coli, with only a few other Enterobacterales species identified. The frequency of ESC resistance was low in E. coli isolates from diagnostic submission (4%) and fecal samples without selective enrichment (5%). Of the ESC-resistant Enterobacterales isolates from selective enrichments, 71%, 18%, 14%, and 8% were positive for blaCMY, blaTEM, blaCTX-M, and blaSHV, respectively. IncI1 followed by IncK were the main incompatibility groups identified for blaCMY plasmids. The blaCTX-M-1 gene was found repeatedly on IncI1 plasmids of the pMLST type 3, while blaCTX-M-15, blaCTX-M-55, and blaCTX-M-65 were associated with a variety of IncF plasmids. Clonal spread of strains carrying blaCTX-M genes between turkey farms was observed, as well as the presence of an epidemic blaCTX-M-1 plasmid in unrelated E. coli strains. In conclusion, Enterobacterales resistant to ESCs were still widespread at low concentration in turkey feces two years after the cessation of ceftiofur use. Although blaCMY-2 is the main ESC resistance determinant in E. coli from Canadian turkeys, blaCTX-M genes also occur which are often carried by multidrug resistance plasmids. Both clonal spread and horizontal gene transfer are involved in parallel in the spread of blaCTX-M genes in Enterobacterales from Canadian turkeys.

Escherichia coli Isolated from Cases of Colibacillosis in Russian Poultry Farms (Perm Krai): Sensitivity to Antibiotics and Bacteriocins.

Escherichia coli strains isolated from case of colibacillosis in Russian poultry farms in the region of Perm Krai were analyzed for their sensitivity to main antibiotics and bacteriocins. Sensitivity profiles for 9 antibiotics and 20 bacteriocins were determined with the disc diffusion method and the overlay test, respectively. Further, with the PCR the presence of several bla and integron 1 genes was revealed and the phylogenetic group for each strain determined. Among the 28 studied E. coli strains 85.7% were resistant to at least three antibiotics, 53.6% to five or more drugs, and 10.7% to eight antibiotics. PCR revealed that the blaTEM gene was harbored by 71.4% of strains and the blaCTX-M gene by 53.6% of strains. The class 1 integrons were found in 28.6% of strains. All of the studied strains were insensitive to ten or more bacteriocins. More than 90% of the studied strains were insensitive to pore-forming colicins of group A and B colicins, while 60.7% were insensitive to colicins with DNase and RNase activity. All of the analyzed strains were insensitive to at least two of the tested microcins. Neither the antibiotic resistance profile nor the bacteriocin resistance profile correlated with phylogenetic group of the strains. Thus, the studied strains were shown to possess high levels of multiple resistance to antibiotics and insensitivity to bacteriocins.

Antibiogram of Escherichia coli Isolated from Avian Colibacillosis in Chitwan District of Nepal

A cross-sectional study was conducted at National Avian Disease Investigation Laboratory, Chitwan to determine antibiogram of Escherichia coli isolated from avian colibacillosis cases of broilers and layers in Chitwan. One hundred and sixty (95 from broilers and 65 from layers) liver samples were collected aseptically during postmortem. Samples were taken purposively from dead birds showing lesions perihepatitis, pericarditis, air-saculitis, omphalitis and egg peritonitis. Isolation and identification were made by examination of cultural characteristics of E. coli in MacConkey’s agar, Eosin methylene blue (EMB) agar, Gram’s staining and biochemical tests. Antibiogram of identified E. coli isolate was evaluated against six antibiotics of six different groups by disk diffusion method following CLSI guidelines. One hundred and three E. coliisolates (73 from broilers and 30 from layers) were isolated from one hundred and sixty samples. Highest resistance was observed against Ampicillin (100%) followed by Co-trimoxazole (86.40%), Doxycycline (46.60%), Levofloxacin (45.63%), Nitrofurantoin (26.21%) and Amikacin (10.68%). Nearly about all (96.12%) isolates from 103 isolated E. coli isolates showed multidrugs resistance to two or more than two antimicrobials. All multidrug resistance isolates showed 16 different patterns with each isolate being resistance to at least two drugs. The multiple antibiotic resistance indexing ranged from 0.2 to 0.8 and proportion of isolates with MAR index greater than 0.2 was 96.12%.&#x0D; Int. J. Appl. Sci. Biotechnol. Vol 8(1): 52-60&#x0D; &#x0D;