The virulence regulator AbsR in avian pathogenic Escherichia coli has pleiotropic effects on bacterial physiology

Avian pathogenic Escherichia coli(APEC)belonging to extraintestinal pathogenic E.coli(ExPEC)can cause severe infections in extraintestinal tissues in birds and humans,such as the lungs and blood.MprA(microcin production regulation,locus A,herein renamed AbsR,a blood survival regulator),a member of the MarR(multiple antibiotic resistance regulator)transcriptional regulator family,governs the expression of capsule biosynthetic genes in human ExPEC and represents a promising druggable target for antimicrobials.However,a deep understanding of the AbsR regulatory mechanism as well as its regulon is lacking.In this study,we present a systems-level analysis of the APEC AbsR regulon using ChIP-Seq(chromatin immunoprecipitation sequencing)and RNA-Seq(RNA sequencing)methods.We found that AbsR directly regulates 99 genes and indirectly regulates 667 genes.Furthermore,we showed that:1)AbsR contributes to antiphagocytotic effects by macrophages and virulence in a mouse model for systemic infection by directly activating the capsular gene cluster;2)AbsR positively impacts biofilm formation via direct regulation of the T2SS(type II secretion system)but plays a marginal role in virulence;and 3)AbsR directly upregulates the acid tolerance signaling system EvgAS to withstand acid stress but is dispensable in ExPEC virulence.Finally,our data indicate that the role of AbsR in virulence gene regulation is relatively conserved in ExPEC strains.Altogether,this study provides a comprehensive analysis of the AbsR regulon and regulatory mechanism,and our data suggest that AbsR likely influences virulence primarily through the control of capsule production.Interestingly,we found that AbsR severely represses the expression of the type I-F CRISPR(clustered regularly interspaced short palindromic repeats)-Cas(CRISPR associated)systems,which could have implications in CRISPR biology and application.

The Pathogenicity of Chicken Pathogenic <i>Escherichia coli</i>Is Associated with the Numbers and Combination Patterns of Virulence-Associated Genes

Various virulence-associated genes or pathogenicity island are responsible for determining the pathogenicity of Escherichia coli strains. However, the correlation of the number and combination patterns of virulence-associated genes in Escherichia coli strains with their pathogenicity remains largely unknown. In this work, 581 chicken Escherichia coli strains were isolated from 1045 liver samples of dead chickens from 50 chicken farms at four provinces in China during 2007-2012. Based on the pathogenic test of SPF chickens, 320 chickens pathogenic Escherichia coli isolates were identified as highly (n = 193), intermediate (n = 98) and low pathogenic (n = 29) strains, respectively. Furthermore, the number of virulence genes in the 320 chicken pathogenic and 50 non-pathogenic Escherichia coli strains was examined. Our results reveal that thirteen virulence genes in Escherichia coli strains were detected, and all strains carried at least two or more than two virulence-associated genes. This study also suggests that highly pathogenic E. coli strains simultaneously carried at least 8 to13 virulence genes while intermediate pathogenic strains carried at least 5 to 8 virulence genes. The number of virulence-associated genes detected in highly pathogenic strains showed there were more significant differences than that in low pathogenic strains (P irp2, fyuA, and colV in high pathogenic strains was significantly higher than that in low and non-pathogenic strains (P irp2, fyuA, iucA, iucD, iutA, papC, iss, tsh, and colV were more often detected in highly and intermediate pathogenic E. coli strains. Taken together, our results provide evidences demonstrating that the pathogenicity of Escherichia coli strains is closely associated with the number and combination patterns of virulence-associated genes.

Differentiation of Avian Pathogenic <i>Escherichia coli</i>Strains from Broiler Chickens by Multiplex Polymerase Chain Reaction (PCR) and Random Amplified Polymorphic (RAPD) DNA

We examined 50 Escherichia coli (E. coli) strains isolated from broiler chickens between January 2013 to March 2014 in order to evaluate the epidemiological prevalence of avian pathogenic E. coli (APEC) in Jordan by multiplex PCR and random amplification of polymorphic DNA (RAPD) tests. The multiplex polymerase chain reaction (PCR) which was used as tentative criteria of APEC targets 8 virulence associated genes;enteroaggregative toxin (astA), Type 1 fimbria adhesion (fimH), iron-repressible protein (irp2), P fimbriae (papC), aerobactin (iucD), temperature-sensitive hemagglutinin (tsh), vacuolating autotransporter toxin (vat), and colicin V plasmid operon (cva/cvi) genes. The number of detected genes could be used as a reliable index of their virulence. E. coli strains already typed as an APEC always harbor 5 to 8 genes, but non-APEC strains harbor less than 4 genes. Assuming the criteria of an APEC is possession of 5 or more virulence associated genes;we found that all 50 E. coli strains were classified as APEC strains. The RAPD analysis showed that the E. coli strains could be grouped into 35 of RAPD types by using these two different RAPD primer sets, RAPD analysis primer 4 5'AAGAGCCCGT5', and RAPD analysis primer 6 5'CCCGTCAGCA3'. The current study confirmed the endemic nature of APEC in broiler flocks in Jordan. It is essential that the biosecurity on poultry farms should be improved to prevent the introduction and dissemination of APEC and other agents. Furthermore, farmers need to be educated about the signs, lesions, and the importance of this agent.

PCR Detection of Pilus-associated Genes and Serotype Identification of Pathogenic Escherichia coli Isolated from Chickens in the Jidong Area

[ Objective] This study aimed to explore the presence of type I pill （fimC gene） and P pill （papC gene） and identify the serotype of pathogenic E. coli isolated from chickens in the Jidong Area. [ Method] Type I pill （fimC gene） and P pill （papC gene） were detected by PCR. The serotype was identified by con- ventional agglutination test. [ Result ] The results showed that 100% of chicken-derived E. coil strains expressed type I pill （fimC gene） ; 39.1% （9/23） of chick- en-derived E. coli strains expressed P pill （papC gene）. In addition, 23 isolates of chicken-derived E. coil were assigned to 14 O serotypes, including O78, O93, O 45, O101, O38, O88, O24, O1, O163, O53, O15, O87, O34 and O29, among which O78 was the dominant serotype that accounted for 42.8% （6/14） of the total strain number. [ Conclusion] Chicken-derived E. coli strains in the Jidong Area belonged to 14 serotypes, and 078 was the dominant serotype; 83.3% of 078 serotvDe E. coli strains expressed both tvDe I Dill and P Dill.

Development of a Multivalent Inactivated Vaccine against Pathogenic Escherichia coli Infection in Forest Musk Deer

A multivalent inactivated Escherichia coli vaccine for forest musk deer by using serotypes O4,O26,and O139 with Al（OH）3 adjuvant was prepared.The vaccine did not cause any adverse reactions in forest musk deer.The immunogenic effects of the vaccine were experimentally investigated in pregnant and young forest musk deer.The serum antibody titers of pregnant and young forest musk deer were determined by performing the micro-agglutination test.The serum antibody titers of pregnant forest musk deer were more stable from 35th to 68th d after the third vaccination,and the serum antibody titers of four pregnant forest musk deer were maintained 25,25,25,and 24 on 68th d after the third vaccination.Young forest musk deer showed serum antibody titers which were obtained due to nursing.Young forest musk deer were administered the first intramuscular vaccine injection at an age of approximately 60 days due to a fall in maternal antibody titers.The serum antibody titers of young forest musk deer were higher after the third vaccination and maintained at approximately the same level until they were 137 days old.The maternal antibodies and the antibodies produced by young forest musk deer could be helpful for protecting the young musk deer from the infections of pathogenic Escherichia coli strains（serotypes O4,O26,and O139）for 137 days after birth（during the nursing period and the period when the forest musk deer were susceptible to diseases）.

Multidrug-Resistant of Escherichia coli and Salmonella spp. Strains in Chicken Feces Intended for Consumption in Open Spaces of Ouagadougou, Burkina Faso

Resistant bacteria can be transmitted to humans through feces or contaminated meat from local chickens. Bacterial strains were isolated from the intestinal contents of 400 local chicken samples from various sales sites. These strains were then characterized using bacteriological and biochemical methods to identify resistant strains. In a study conducted in Ouagadougou, we systematically collected chicken fecal samples from 20 locations across the city, followed by isolation and identification of Salmonella spp. using specific enrichment and culture methods, as well as Escherichia coli. Bacterial strains were characterized using antibiotic resistance profiles were determined through agar diffusion tests, revealing sensitivity or resistance to a range of antibiotics based on established scientific criteria. The results showed that out of the 400 samples collected, 81.25% and 63.5% were contaminated by Escherichia coli and Salmonella spp., respectively. Among these, 86.15% of identified Escherichia coli and 50.78% of Salmonella spp. displayed resistance to at least one tested antibiotic. Among 280 Escherichia coli isolates identified resistant to at least one antibiotic, 31.07% were resistant to cefotaxime (CTX), 20.35% to ceftazidime (CAZ), 21.07% to ceftriaxone (CTR), 75% to amoxicillin clavulanic acid (AMC), 23.57% aztreoname (ATM) and 27.14% were resistant to imipenem (IMP). In the case of the 129 Salmonella spp. isolates resistant to at least one tested antibiotic, 34.88% were resistant to CTX;41.08% to CAZ;35.65% to CTR, 92% to AMC, 39.53% to ATM and finally 47.28% were resistant to IMP. Our study revealed high prevalence of resistance in bacterial strains isolated from local chickens sold outdoors in Ouagadougou. These findings raise significant public health concerns, due to the possible transmission of these resistant strains to humans through the consumption of contaminated meat, thus complicating the treatment of bacterial infections.

Distribution of Virulence-Associated Genes of Avian Pathogenic Escherichia coli Isolates in China

216 avian pathogenic Escherichia coli （APEC） isolates were obtained from poultry with colibacillosis in different areas of China. Among them, 195 were serotyped as 078, 088, and 093. Thirteen virulence-associated genes, including fimC, iucD, iss, tsh, fyuA, irp2, eaeA, hlyE, colV, papC, stx2f, vat, and astA, were submitted to PCR amplification. The fimC gene was the most prevalent with a detection rate of 93.6%, followed by iucD （70.8%）, iss （58.8%）, and tsh （51.4%） in APEC isolates. The detection rate of high pathogenicity islands （HPI）-associatedfyuA and irp2 genes were both 44.9%, with no LEE （the locus of enterocyte effacement） island-associated gene eaeA detected. In terms of distribution patterns of the 13 virulence-associated genes, 5 isolates harborbed 10 genes, 19 isolates contained onlyfimC gene, and only 4 isolates had no virulence-associated gene detected. Different correlations of the virulence-associated genes with O serotypes were also investigated and 50% 078 isolates had a gene distribution patterns of fimC^＋iucD^＋irp2^＋fyuA^＋iss^＋colV^＋tsh^＋.

Fosfomycin Resistance in Avian Pathogenic Escherichia coli Isolates

Fosfomycin, a broad-spectrum antibiotic against both Gram-positive and Gram-negative bacteria, is very important in the clinic but many fosfomycin-resistant bacteria have been isolated from patients. In this study, the resistance mechanism of three fosfomycin-resistant avian pathogenic Escherichia coli （APEC） strains （JE1, IF7 and CD11） isolated from septicemic chickens were analyzed. The results showed that their fosfomycin-resistance mechanisms were different. An alteration in the glpT transport system was the main reason of the fosfomycin-resistance mechanisms of strain IF7. Compared with the control stain BL21, the capacity of fosfomycin-uptake was low in all these three stains （JE 1 〉IFT〉CD 11）. Sequence results of murA showed that there were more than 10 sites of nucleotide mutation, but only one amino acid mutation T116A showed in CD11. Real-time detection test showed that the expression level of the murA gene of the three stains was significantly increased （four times increase in strain CD11 and two times increase in strains JE1 and IFT）. The transformation and recombinant test showed that the recombinant bacteria with the murA of JE1 and CD11 showed high minimal inhibitory concentration （MIC） against fosfomycin. From the results of this research, it showed that most of the fosfomycin- resistance mechanisms once showed in patient bacteria have appeared in the APEC strains and the fosfomycin-resistance mechanism of the three APEC isolates was different.

Isolation, Identification and Drug Sensitivity Test of a Pathogenic Escherichia coli Strain from Minks with Diarrhea

[Objectives] The study aimed to identify the pathogen that causes diarrhea in minks. [Methods] Liver tissues were aseptically collected from dead minks with diarrhea. By bacterial isolation and culture,morphological observation,biochemical test and pathogenicity test,the isolated strain was identified as pathogenic E. coli. [Results]The pathogen causing diarrhea in minks was confirmed as a pathogenic E. coli strain. Drug sensitivity test indicated that the isolated pathogenic E. coli strain was highly sensitive to ceftazidime,cefotaxime,enrofloxacin,florfenicol and cephradine,moderately sensitive to ampicillin,ciprofloxacin,amikacin,doxycycline,lincomycin and gentamycin,and resistant to amoxycillin,neomycin,spectinomycin,polymyxin and penicillin. [Conclusions] This study provided reference for the prevention and control of abortion in female minks in Qinhuangdao region.

Screening of Chinese Herbal Medicines Resistant to Chicken Escherichia coli and Infectious Laryngotracheitis Virus

[Objective] This study aimed to screen Chinese herbal medicines resistant to Chicken Escherichia coli and infectious laryngotracheitis virus. [Methed] Conven- tional punch method, test tube method and plate dilution method were adopted for in vitro susceptibility test of chicken E, coil strains O5 and O8 using 13 kinds of Chi- nese herbal medicines including Sanguisorba officinalis, Coptis chinensis, Anemar- rhena asphodeloides, Strobilanthes cusia, Agastache rugosa, etc.; chicken embryo inoculation experiment was adopted to screen Chinese herbal medicines resistant to chicken infectious laryngotracheitis virus. [Result] Sanguisorba officinalis, Fructus mume, Rheum officinale, Coptis chinensis, Herba Taraxaci, Anemarrhena asphode- Ioides, Scutellaria baicalensis and Rhizoma Fagopyri Cymosi had ideal antibacterial effect against chicken E. coil strain O5; Sanguisorba officinalis, Fructus mume, Rheum officinale, Coptis chinensis, Herba taraxaci and Rhizoma Fagopyri Cymosi had ideal antibacterial effect against chicken E. coil strain 08; other Chinese herbal medicines showed relatively poor or no antibacterial effect. Results of chicken embryo inoculation experiment showed that nine kinds of Chinese herbal medicines showed relatively strong anti-lLTV effect, including Forsythia suspensa, Radix Isatidis, Fofium isatidis, Flos Ionicerae, Radix codonopsis, Radix astragali, Atractylodes, Radix gly- cyrrhizae, and Pericarpium granati. [Conclusion] The study laid the foundation for fur- ther development of Chinese herbal compound preparations to treat chicken cofibacil- Iosis, infectious laryngotracheitis and other bacterial, viral diseases.

Study on Outer Membrane Protein Patterns of Escherichia coli O38,O53 and O75 Isolated from Chickens

[Objective] This study aimed to investigate the outer membrane protein （OMP） patterns of Escherichia coli 038, 053 and 075 isolates from chickens. [Method] Eight pathogenic E. coil isolates with various serotypes were used as experimental materials to extract OMP by using supersonic schizolysis method and Sarcosyl. After SDS-PAGE electrophoresis, OMP patterns of the extracted products were determined based on the OMP model diagram. [Result] OMP of eight E. coil isolates with three serotypes were divided into three patterns, to be specific, 2 075 isolates respectively belonged to OMP-I and OMP-II pattern, 1 053 isolate belonged to OMP-II pattern, and 5 038 isolates belonged to OMP-I and OMP-III pattern. [Conclusion] Experimental results showed that E. coli isolates with the same serotype may belong to completely different OMP patterns, while serologically unrelated isolates may belong to the same OMP pattern. OMP of E. coil isolates with the same serotype may generate genetic differentiation; in addition, OMP of E. coli isolates with different serotypes may have different genetic correlation.

Effects of dietary supplementation of probiotic,Clostridium butyricum,on growth performance,immune response,intestinal barrier function,and digestive enzyme activity in broiler chickens challenged with Escherichia coli K88

Background： Colibacillosis caused by enterotoxigenic Escherichia coil （E. coil} results in economic losses in the poultry industry. Antibiotics are usually used to control colibacillosis, however, E. coli has varying degrees of resistance to different antibiotics. Therefore the use of probiotics is becoming accepted as an alternative to antibiotics. In this study, we evaluated the effects of Clostfidium butyricum （C. butyficum） on growth performance, immune response, intestinal barrier function, and digestive enzyme activity in broiler chickens challenged with Eschefichia coli （E. coil） K88. Methods： The chickens were randomly divided into four treatment groups for 28 days. Negative control treatment （NC） consisted of birds fed a basal diet without E. coil K88 challenge and positive control treatment （PC） consisted of birds fed a basal diet and challenged with E. coil K88. C. buO/ricum probiotic treatment （CB） consisted of birds fed a diet containing 2 x 107 cfu C. buO/ricum/kg of diet and challenged with E. coil K88. Colistin sulfate antibiotic treatment （CS） consisted of birds fed a diet containing 20 mg colistin sulfate/kg of diet and challenged with E. coil K88. Results： The body weight （BW） and average day gain （ADG） in the broilers of CB group were higher （P 〈 0.05） than the broilers in the PC group overall except the ADG in the 14-21 d post-challenge. The birds in CB treatment had higher （P 〈 0.05） concentration of tumor necrosis factor-a （TNF-a） at 3 and 7 d post-challenge, and higher （P 〈 0.05） concentration of interleukin-4 （IL-4） at 14 d post-challenge than those in the PC treatment group. The concentration of serum endotoxin in CB birds was lower （P 〈 0.05） at 21 d post-challenge, and the concentrations of serum diamine oxidase in CB birds were lower （P 〈 0.05） at 14 and 21 d post-challenge than in PC birds. Birds in CB treatment group had higher （P 〈 0.05） jejunum villi height than those in PC, NC, or CS treatment at 7, 14, and 21 d post-challenge. In comparison to PC birds, the CB birds had lower （P 〈 0.05） jejunum crypt depth during the whole experiment. The birds in CB or CS treatment group had higher （P 〈 0.05） activities of amylase and protease at 3, 7, and 14 d post-challenge, and higher （P 〈 0.05） activity of lipase at 3, 7 d post-challenge than PC birds.

Dietary supplementation of Bacillus subtilis influenced intestinal health of weaned pigs experimentally infected with a pathogenic E. coli

Background: There is growing evidence to support the beneficial effects of supplementing direct-fed microbials(DFM) on performance, health status, and immune responses of weaned pigs. Therefore, the objective of this study was to investigate dietary supplementation of Bacillus subtilis(DSM 25841) on growth performance, diarrhea, gut permeability and immunity of weaned pigs experimentally infected with a pathogenic F-18 Escherichia coli(E. coli).Results: The F18 E. coli infection reduced(P < 0.05) growth performance and intestinal villi height, whereas increased(P < 0.05) diarrhea and transcellular and paracellular permeability in the jejunum compared with non-challenged control. Supplementation of Bacillus subtilis linearly enhanced average daily gain of E. coli infected pigs from d 0 to 5 post-inoculation(PI)(P < 0.05) and d 0 to 11 PI(P = 0.058). Supplementation of high dose of Bacillus subtilis reduced(P < 0.05) both transcellular and paracellular permeability on d 5 and d11 PI compared with the E. coli infected pigs fed with control diet. E. coli infection up-regulated(P < 0.05)the m RNA expression of SLC5 A10(soluble carrier family 5 member 10) and MUC2(mucin 2) on d 5 PI, but down-regulated(P < 0.05) expression of SLC5 A10, MUC2, and CLDN1 on d 11 PI in jejunal mucosa when pigs were fed with the control diet. Supplementation of Bacillus subtilis linearly up-regulated(P < 0.05) the m RNA expression of CFTR and ZO1 on d 5 PI and SLC5 A10 and MUC2 on d 11 PI in jejunal mucosa of E. coli infected pigs. In addition, E. coli infection increased(P < 0.05) the m RNA expression of several immune genes(IL1 A, IL1 B, and IL7 on d 5 PI, and IL1 B, IL6, IL7, and TNF on d 11 PI) in the ileal mucosa of weaned pigs. Inclusion of Bacillus subtilis to control diet linearly down-regulated gene expression of IL1 A on d 5 PI(P = 0.07) and IL6 on d 11 PI(P < 0.05) in ileal mucosa of E. coli infected pigs.Conclusions: Supplementation of Bacillus subtilis(DSM 25841) enhanced growth rate and improved gut barrier function of weaned pigs experimentally infected with a pathogenic E. coli.

Escherichia coli tetracycline efflux determinants in relation to tetracycline residues in chicken

Objective:To screen for Escherichia coli(E.coli)resistant to tetracycline,followed by identification of tet efflux genes by polymerase chain reaction(PCR).In addition,detection of tetracycline residues in chicken livers and kidneys were conducted using high performance liquid chromatography-tandem quadrupole mass spectrometry(HPLC-MS-MS).Methods:Strains of E.coli were isolated from samples of chicken colon and screened for tetracycline resistance.Tetracycline genes conferring resistance(Tc^r)were detected by polymerase chain reaction(PCR).Most of the isolates were resistant to tetracycline(97.9%).Results:PCR analysis indicated that Tc^r E.coli R-plasmids contained tet(A),tet(B)and a combination of both efflux genes.None of the isolates contained other efflux tet genes tet(C,D,E and Y).High performance liquid chromatography-tandem quadrupole mass spectrometry(HPLC-MS-MS),a sensitive technique,was used to detect residues of chlortetracycline(CTC),oxytetracyeline(OTC),doxveycline(DC)in chicken livers and kidneys.The samples containing tetracycline residues were at 0.13-0.65pg/μL levels.Conclusions:Tetracycline and other antibiotics are commonly used in the poultry and meat production industry for prevention of microbial infections.Multiple antibiotic resistant bacteria in Oman have increased to alarming levels,threatening public health,domestic and may have adverse effect on environment.

Antibiotic susceptibility and molecular characterization of resistance genes among Escherichia coli and among Salmonella subsp. in chicken food chains

Objective: To investigate the occurrence of resistance genes among Escherichia coli(E. coli) and Salmonella subsp. isolated in chicken food chains in Phnom Penh, 2012–2013.Methods: Six hundred eighty two E. coli and 181 Salmonella Albany, Corvallis, and Kentucky strains were examined for susceptibilities to eight antimicrobials and following resistance genes were identified by PCR: blaTem, Str A, aad A, sul1, sul2, gyr A, Tet(A), and Tet(B).Results: E. coli presented high resistances to tetracycline, amoxicillin, and sulfamethoxazole(63.1%–76.1%). Salmonella Albany and Salmonella Kentucky traduced high resistance percentages to amoxicillin, tetracycline, sulfamethoxazole, and nalidixic acid(84.6%–100%). Among amoxicillin-resistant isolates, blaTemgenes were observed for 62% of E. coli isolates and 20% of 65 Salmonella Kentucky. The Str A gene was prevalent in 36% of 331 aminoglycoside-resistant E. coli and 90% of 40 aminoglycoside-resistant Salmonella Corvallis. The sul2 gene was predominant among sulfamethoxazole-resistant isolates, for 56% of 431 E. coli and 53% of 66 Salmonella Corvallis; the sul1 gene was observed in 54% of Salmonella Albany. The Tet(A) resistance gene was prevalent in E.coli(86%), Salmonella Corvallis(82%), Salmonella Kentucky(84%). High percentages of gyr A genes observed among nalidixic-acid resistant E. coli(91%), Salmonella Albany(92%), Salmonella Corvallis(75%) and Salmonella Kentucky(85%).Conclusions: Important occurrences of resistance gene were observed among E. coli and Salmonella in chicken food chains in Cambodia.

Antimicrobial Drug Resistance Pattern of <i>Escherichia coli</i>Isolated from Chickens Farms with Colibacillosis Infection

Colibacillosis refers to any localized or systemic infection caused entirely or partly by avian pathogenic Escherichia coli (APEC). Colibacillosis in mammals is most often a primary enteric or urinary tract disease, whereas colibacillosis in poultry is typically a localized or systemic disease occurring secondarily when host defenses have been impaired or overwhelmed by virulent E. coli strains. The purpose of this study was to investigate the antimicrobial drug resistance pattern of Escherichia coli isolated from broiler chickens farms with colibacillosis infection. Dead birds from commercial broiler chicken farms showing signs of colibacillosis were necropsied and swab samples were collected from internal organs and blood aseptically for the isolation of Escherichia coli. Pure colonies of the bacteria were isolated on solid media and the isolates were identified as E. coli based on morphological and biochemical characteristics. For determination of susceptibility to antibacterial agents, the disc diffusion method on Muller-Hinton agar was used. The following antimicrobial agents were tested: gentamycin, oxytetracyline, colistin, ciprofloxacin, doxycycline, nalidixic acid, co-trimoxazole (trimethoprim-sulfamethoxazole), norefloxacin, lincospectin and cefuroxime. The drug resistance patterns of the organisms were determined as a percentage and reported at three levels: susceptible, intermediate and resistant. All the isolates of Escherichia coli showed resistance to several antibiotics and a pattern of multiple drug resistance was observed. The highest rate of resistance was observed against nalidixic acid (100%) and the least rate of resistance was observed against gentamycin (17%). According to the results of this research care must be taken to avoid secondary infection (colibacillosis) in chicken farms and also avoid in careless antimicrobial consumption in food animals including chickens.

Isolation and Identification of Drug-resistant Escherichia coli Strains from Chickens

[Objective] This study aimed to isolate and identify the drug-resistant Es- cherichia coli strains from chickens. [Method] E. coli strains were isolated from the fecal samples collected from five chicken farms around Shangqiu City, and verified by biochemical and pathogenic assay. [Result] Among the 35 isolated E. coli stains, 11 E. coil stains were sensitive to florfenicol, amikacin, neomycin and gentamicin; 12 E. coli stains were moderately sensitive to ciprofloxacin, doxycycline and norfloxacin; 15 E. coil stains were resistant against erythromycin, penicillin and streptomycin. [Conclusion] Strengthening biosecurity measures, rationally using vaccine and choosing effective antibiotics are the most cost-efficient methods to control E. coli.

Prevalence of Extended Spectrum Beta-Lactamase-Producing Escherichia coli in Broiler Chickens in YaoundéCapital City of Cameroon

Background: Escherichia coli are ubiquitous bacteria colonising both humans and animals. Extended spectrum β-lactamase-producing E. coli has been selected as a suitable indicator for the monitoring and surveillance of antimicrobial resistance. Death due to resistant bacteria is continuously rising in Cameroon, but the contribution of the aviary sector is not well studied. Therefore, this study aimed to investigate the resistance profile of extended spectrum beta-lactamases-producing Escherichia coli strains, isolated from faeces of broiler chickens in Yaoundé, capital city of Cameroon. Methods: A cross-sectional descriptive study was carried out from February to June 2020. Escherichia coli were isolated from samples of broilers in poultry farms in Yaoundé and submitted to the extended spectrum β-lactamase screening. The logistic regression was used to assess the statistical association of a significance threshold p-value of 0.05. Results: Out of 385 faecal samples collected in broiler farms, 114 Escherichia coli isolates were obtained out of which 30 (26.32%) were Extended Spectrum Beta-Lactamases-producing Escherichia coli. These isolates revealed high resistance to all antibiotic families. Poor storage conditions for feeds and the proximity to latrines, the troughs on the ground, the lack of foot bath and uniforms, the inadequate treatment of faeces, the poor usage of preventive antibiotics and the lack of water treatment have been identified as risk factors to faecal carriage of ESBL-producing Escherichia coli. Conclusion: This work reveals the emergence of Extended Spectrum Beta-Lactamases-producing Escherichia coli in poultry farms in Yaoundé and the failure in the biosecurity system. As such, the awareness of poultry breeders on the respect of biosecurity measures may be an effective tool to tackle antimicrobial resistance, specifically in livestock industries using a One Health approach.

Effective treatment of resistant <i>Escherichia coli</i>infection, with sulphadimidine stabilized in a synthetic Aluminium-Magnesium Silicate

To investigate if Aluminium-Magnesium Silicate (AMS) could make drugs regain effects against resistant pathogens, its effect was tested on sulphadimidine against sulphadimidine-resistant Escherichia coli. Two groups of chicks infected with sulphadimidine-resistant E. coli were treated at sulphadimidine dose rate of 1 g/litre of drinking water, with sulphadimidine and with an AMS-sulphadimidine drug formulation, respectively. Two other groups were similarly treated at sulphadimidine dose rate of 0.75 g/litre, while the fifth group served as control. Mean titres of the bacterium in bile of the chicks were compared. Titres, 119,200 ± 55,800 CFU/mL of the group treated with sulphadimidine at rate of 1 g/ litre and 14,800 ± 1700 CFU/mL of the group treated at rate of 0.75 g/litre, did not vary from 33,200 ± 5200 CFU/mL of the control (P > 0.05) but 295,200 ± 106,400 CFU/ml of the group treated at rate of 1 g/litre, with the AMS-sulpha- dimidine drug was significantly (P < 0.05) higher than that of the control while 5200 ± 1400 CFU/mL of the group treated at dose of 0.75 g/litre, with the AMS-sulphadimidine drug, reduced significantly (P < 0.05).

UV-TiO_2 photocatalytic disinfection and photoreactivation of pathogenic bacterium in municipal wastewater

The disinfected bacteria will be a photoreactivation under the irradiation of the sunlight,and the light intensity plays an important role in the bacteria resurrection.The effect of light intensity on photoreactivation of Escherichia coli(E.coli) and Enterococcus faecalis(E.faecalis) in secondary effluents which were disinfected respectively by pure UV and UV-TiO_2 was investigated.The results show that the disinfection efficiency of UV-TiO_2 is much higher than that of the pure UV disinfection.The photoreactivation rate of E.coli is much higher in pure UV disinfection than in UV-TiO_2 photocatalytic disinfection.Under high light intensity in UV-TiO_2 disinfection,high resurrection rate can be induced.However,a higher resurrection rate can be introduced even under low light intensity in pure UV disinfection alone.Meanwhile,UV-TiO_2 disinfection has a strong inhibition effect on E.faecalis photoreactivation.When the light intensity is lower than 21 μW/cm^2,nearly no resurrection of E.faecalis occurs after 72 h resurrection irradiation,and a little resurrection rate is observed only under a strong photoreactivating light intensity.