Prevalence of Drug Resistant Uropathogenic Escherichia coli from Immunocompromised Diabetic Patients Attending Selected Health Facilities in Benue State

Escherichia coli is the commonest bacterial uropathogen of UTIs, the commonest infections in immunocompromised diabetic patients. Better understanding of their main resistance mechanisms to commonly used antibacterial agents will help to reduce the burden of this infection. The prevalence of drug resistant uropathogenic Escherichia coli isolates from immunocompromised diabetic patients attending selected health facilities in Benue State was investigated. Two hundred and ninety-six midstream urine samples were collected for both study and control diabetic patients. Bacterial isolation was done using semi-quantitative method. Drug resistant Escherichia coli were identified as multidrug resistant (MDR), extensive drug resistant (XDR) and pan-drug resistant organisms (PDR). Statistical significance was considered at p E. coli isolates from the study and control subjects with overall prevalence of 20.9% and 8.4% respectively. The isolates were highly resistant to penicillin (ampicillin), monobactam (aztreonam), older quinolone (nalidixic acid) whereas the majority of them showed high susceptibility to aminoglycoside (streptomycin), cephalosporin (cefotaxime) and carbapenem (imipenem). None showed complete susceptibility to all the tested antibiotics. Twenty-five E. coli were identified in this MDR, eight, XDR while 5 were PDR. High numbers of drug resistant E. coli isolates were identified in the study group of which 25 were MDR, 8 XDR while 5 were PDR isolates. High prevalence of UTI and drug resistant isolates occur in diabetic patients with hyperglycemic condition.

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.

Impact of Genetic Diversity of Uropathogenic Escherichia coli and Klebsiella pneumoniae Strains on the Dissemination of Extended Spectrum Beta-Lactam Resistance Genes in Côte d’Ivoire

The increase and spread of bacterial resistance to extended-spectrum beta-lactam antibiotics are reported in many infections and are a real public health problem worldwide. Drug pressure is a factor that favors the emergence of a population of better adapted bacteria. However, there is no literature highlighting the genetic diversity and evolutionary structure of E. coli and K. pneumoniae in an environment with high selection pressure in Côte d’Ivoire. The objective of this study was to evaluate the genetic diversity of E. coli and K. pneumoniae strains circulating at the HKB Hospital in Abobo and at the Daloa Regional Hospital and its impact on the dissemination of extended spectrum beta-lactam resistance genes. A total of 39 strains isolated from the urinary tract of infected patients, including 30 strains of E. coli and 9 strains of K. pneumoniae were studied. A total of 39 strains isolated from the urinary tract of infected patients, including 30 strains of E. coli and 9 strains of K. pneumoniae were studied. From genomic DNA extracts, ESBL resistance genes were amplified by PCR and sequenced, in addition to genetic typing by ERIC-PCR. The data obtained were submitted to genetic and bioinformatics analyses. The results have shown a genetic diversity important in E. coli and K. pneumoniae with diversity indexs (SID) ranging from 0.5 to 0.77. The genetic structure of the bacterial species studied has shown a clonal distribution of strains with clones expressing TEM-9 and CTX-M-15 variants. Also, this clonal structure was correlated with the spread of resistance genes in E. coli and K. pneumoniae. The spread of resistant clones is a factor that might limit the fight against antibiotic resistance.

Phenotypic and Genotypic Antibiotic Resistant Diarrheagenic Escherichia coli Isolated from Patients with Diarrhea in Ouagadougou, Burkina Faso

Background: The emergence and spread of multidrug-resistant bacteria have become a major public health problem worldwide, particularly in developing countries such as Burkina Faso. This study aims to determine phenotypic and genotypic antibiotic resistant diarrheagenic Escherichia coli (DEC) from patients with diarrhea in Ouagadougou, Burkina Faso. Methodology: Microbiological and biochemical analysis were done to detect two hundred and ninety-two (292) strains. The susceptibility of the strains to antibiotics was determined by the agar disc diffusion method. 16-plex-PCR assays were carried out to detect both virulence and resistance genes encoding betalactams, quinolones, phenicols, tetracyclines and virulence gene of DEC. Results: Diarrheagenic Escherichia coli was detected in 8% (23/292) of patients with diarrhea using the 16-plex-PCR and 39.1% (9/23) of the DEC detected carry at least one resistance gene. Resistance rate in disc diffusion test was 86.96% to tetracycline, 65.23% to cotrimoxazole, 17.4% to nalidixic acid, 17.4% to norfloxacin, 17.4% to ciprofloxacin, 13.04% to ceftriaxone, 13.04% to cefotaxime, 8.7% to gentamicin, 8.7% to Chloramphenicol, 0% to netilmicin. The prevalence of different resistance genes in the studied strains varied from 44.4% to 5.5%. The gene Tet coding for resistance to tetracycline was found in 8 strains (44.4%). The CatA gene coding for resistance to Chloramphenicol was detected in 38.9% of isolates. The qnrS, blaSHV and blaOXA genes were each detected in 5.5% of isolates. No strain hosts the qnrA, qnrB and blaTEM genes. Conclusion: This study identified β-lactams, quinolones, phenicols and tetracyclines resistance genes in DEC isolates from patients with diarrhea in Ouagadougou, Burkina Faso. These results indicate the need for a surveillance program to reduce the prevalence of resistance to Enterobacteriaceae strains in hospitals.

Performance Parameters:Demobilization Antibiotic Resistant Bacteria(ARB)and Carrying Genes(ARG)in Wastewater Disinfection

The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.

Prevalence and Resistance Profile of Muenchen Cefotaximase (CTX-M) Group 1 Extended Spectrum Beta-Lactamase (ESBL)-Producing Uropathogenic Escherichia coli Strains in Dakar, Senegal

Background: Extended-spectrum beta-lactamase (ESBL) producing bacteria are a real public health problem, particularly in Africa. Among these ESBLs, there are the Muenchen Cefotaximase (CTX-M) described all over the world of which the most frequent is the CTX-M of group 1 particularly the CTX-M-15 variant. The objective of this study was to determine the prevalence of CTX-M group 1 ESBL-producing Escherichia coli strains and to test their antibiotics susceptibility profile. Methodology: A retrospective cross-sectional descriptive study was conducted to detect ESBL-secreting Escherichia coli strains by the synergy test. Identification of CTX-M type ESBL from group 1 was performed using the NG-Test CTX-M rapid diagnostic test (NG-Biotech®). Antibiotic susceptibility profile was determined using CA-SFM/EUCAST guidelines 2019. Data entry and statistical analysis were performed with Excel version 2010 and SPSS 20.0 respectively. Results: Eighty-two ESBL-producing Escherichia coli strains were tested. A group 1 CTX-M ESBL was detected in 75.6% of the strains (n = 62). These strains were highly resistant to cefotaxim (100%), aztreonam (100%), ceftazidim (85.4%) and cefepim (66.1%). They were also resistant to quinolones, gentamycin and sulfadoxine-trimethoprim combination. However, these strains showed sensitivity to ertapenem (100%), cefoxitin (69.3%), tigecyclin (66%), and amikacin (66.1%). The combination of piperacillin and tazobactam was active on 30.6% of the strains against 6.4% for the combination of amoxicillin and clavulanic acid. Conclusion: The CTX-M type ESBL of group 1 was present in the majority of ESBL-producing Escherichia colis trains. Despite the production of this enzyme conferring resistance to most beta-lactam antibiotics, some antibiotics remain active to treat infections caused by these germs.

Potential antibacterial activity of berberine against multi drug resistant enterovirulent Escherichia coli isolated from yaks(Poephagus grunniens) with haemorrhagic diarrhoea

Objective:To evaluate the antimicrobial efficacy of berberine,a plant alkaloid.Methods:Five multi-drug resistant（MDR） STEC/EPEC and five MDR ETEC isolates from yaks with haemorrhagic diarrhoea were selected for the study.Antibacterial activity of berberine was evaluated by broth dilution and disc diffusion methods.The binding kinetics of berberine to DNA and protein was also enumerated.Results:For both categories of enterovirulent Escherichia coli（E.roli） isolates, berberine displayed the antibaclerial effect in a dose dependent manner.The MIC50 of berberine chloride for STEC/EPEC isolates varied from 2.07μM to 3.6μM with a mean of（2.95±0.33）μM where as for ETEC strains it varied from 1.75 to 1.96μM with a mean of（1.87±0.03）μM. Berberine bind more tightly with double helix DNA with Bmax and Kd of（24.68±2.62） and（357.8±57.8）,respectively.Berberine reacted with protein in comparatively loose manner with Bmax and Kd of（18.9±3.83） and 【286.2±113.6),respectively.Conclusions:The results indicate clearly that berberine may serve as a good antibacterial against multi drug resistant E.coli.

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).

Detection of Drug Resistance in Escherichia coli Isolated from Animals and ERIC Analysis of Multidrug-resistant Strains

The drug resistance of Escherichia coli from animals was detected in Shandong Province in 2016,the gene mapping of Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR) of multidrug-resistant isolates were analyzed,and then the relationship between ERIC-PCR genotyping and drug resistance of highly-resistant E.coli with multidrug resistance was discussed.A total of 110 E.coli isolates were separated and identified from diseased swine and avian,and their resistance to 10 kinds of antimicrobials was determined by the agar dilution method.Twenty highly-resistant isolates with multidrug resistance were selected to carry on the ERIC-PCR,followed by cluster genetic analysis according to the DNA fingerprints.The swine-sourced E.coli isolates possessed serious resistance against several kinds of antimicrobial agents,for example,all isolates were tolerant to florfenicol,doxycycline and ampicillin (100%),but had a relative lower resistance rate to cefotaxime sodium (57.14%).The same situation was observed in the poultry-sourced E.coli isolates,which had a resistance rate of 95.51% against florfenicol,while the lowest rate of 61.80% appeared on ciprofloxacin.Analysis of ERTIC showed dispersive fingerprint patterns of highly-resistant and multidrug- resistant isolates which represented a multiple clone resources,and there were certain correlation between the B genotype and the drug-resistant characteristics.It indicated that the animal-sourced E.coli isolates had a high level of drug resistance and were multidrug-resistant,which meant there was severe antibiotic resistance against not only different kinds of antibiotics but also different drugs of the same kind.The highly-resistant E.coli isolates with multidrug resistance had no apparent species preference,while their spread and pervasion posed a potential threat to the development of animal husbandry and the public health security.

Use of a naturally occurring codon bias for identifying topoisomerase mutations in ciprofloxacin resistant <i>Escherichia coli</i>using PCR and future prospects with other bacterial genera: A pilot study

We developed a novel PCR method aimed at identi- fying and amplifying native codon sequences of muta- tion-prone amino acids in DNA gyrase implicated in quinolone resistance using a naturally occurring co- don bias in E. coli DNA gyrase A.

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.

Transmission of Carbapenem Resistance Between Human and Animal NDM-Positive Escherichia coli Strains

Although carbapenem use is prohibited in animals in China,carbapenem-resistant Escherichia coli(CREC),especially New Delhi metallo-β-lactamase(NDM)-producing strains,are widely prevalent in foodproducing animals.At present,the impact of livestock-associated CREC strains on human populations at the national level is unknown.Here,we conduct a retrospective cross-sectional study to investigate the prevalence of CREC from clinical settings across 22 Chinese provinces or municipalities and analyze anthropogenic factors associated with their presence.We also ascertain the blaNDMand blaKPCabundance among pig and chicken farms and present a detailed genomic framework for CREC of animal and human origin.Overall,631/29799(2.1%)clinical Escherichia coli(E.coli)isolates were identified as CREC.Multivariable analysis revealed that being male,an age below 1,an age between 13 and 18,provinces with greater chicken production,and provinces with higher pig production were associated with higher odds of CREC infection.In general,73.8%(n=45/61)of pig farms and 62.2%(n=28/45)of chicken farms had a blaNDMabundance of 1×10^(-5)to 1×10^(-3)and 1×10^(-3)to 1×10^(-2),respectively.Among all the Chinese NDM-positive E.coli(n=463)available at the National Center for Biotechnology Information(NCBI),the genomic analysis revealed that blaNDM-5and Inc X3 were the predominant carbapenemase gene-plasmid combination,while a highly homogeneous relationship between NDM-positive isolates from humans and animals was demonstrated at the plasmid and core genome levels.All the findings suggest frequent CREC transmission between humans and animals,indicating that further discussions on the use of antibiotics in animals and humans are needed,both in China and across the globe.

Low Prevalence of Carbapenem Resistance in Clinical Isolates of Extended Spectrum Beta Lactamase (ESBL) Producing <i>Escherichia coli</i>in North Central, Nigeria

Extended Spectrum Beta Lactamase (ESBL) producing Escherichia coli is a global cause of life threatening infections. We determined the presence of ESBL and carbapenemase production in clinical isolates of E. coli and their antibiotic susceptibility. Clinical isolates of community and hospital acquired E. coli from 220 patients seen at a tertiary hospital were evaluated. Antibiotic susceptibility testing was by the modified Kirby-Bauer protocol while ESBL production was determined by the Double Disk Synergy Test (DDST). Carbapenem resistance was confirmed by the Modified Hodge Test. Of the 220 isolates, 122 (55.5%) were from females;41 (18.6%) were ESBL positive. About 90% of the ESBL producing isolates were resistant to nine of the 15 antimicrobial agents tested. However, only one (2.4%) of the 41 ESBL producing isolates exhibited carbapenem resistance. The ESBL negative isolates were susceptible to Meropenem (100%), Cefepime (97.8%), Ceftriaxone (96.6%) and Cefotaxime (96.6%). All the ESBL producing isolates harbored detectable plasmids with sizes ranging from 2322 to 23,130 base pairs. Our findings show that although multidrug resistant ESBL producing E. coli are prevalent in both the hospital and the community in this environment, carbapenem resistance is still low. We recommend that institutions develop guidelines for the early phenotypic detection of ESBLs and carbapenem resistance.

Burden of Multidrug-Resistant Escherichia coli in Pigs Slaughtered in Uganda and Its Implication on Veterinary Public Health

Antimicrobial resistance by bacteria and other microbes has become a global public and animal health threat. In this cross-sectional study, assessed the abattoir workers’ practices regarding pork handling and we investigated antimicrobial susceptibility patterns of Escherichia coli isolated from pigs brought for slaughter at Wambizzi, Uganda’s main pig abattoir. Rectal swabs were collected from a total of 176 live pigs prior to slaughter. Additionally, 24 swabs were taken from the abattoir floor environment. The collected swabs were cultured for the detection and isolation of E. coli followed by antibiotic susceptibility tests. Regarding pork handling practices, absence of hand washing facilities was observed and none of the workers cleaned/disinfected their equipment between slaughters while slaughters took place on the unhygienic floors of the inspection room. Overall, high prevalence (85.1%) of multi-drug resistant E. coli was detected in pigs received from all the regions of Uganda. Swine E. coli isolates exhibited high resistance against erythromycin (87.4%) and the least resistance against ciprofloxacin at 2.3%. At regional level, E. coli isolates from the central region of Uganda showed higher prevalence of multidrug resistant E. coli isolates as follows;amoxicillin (30.4%, p-value = 0.007), erythromycin (34.8%, p-value = 0.002), streptomycin (40.7%), ciprofloxacin (100%), oxytetracycline (31%) and sulphamethoxazole-trimethoprim (42.9%). Furthermore, multidrug-resistant E. coli was also confirmed in the immediate environment where pigs were gathered and slaughtered. From these environmental isolates, the highest resistance was confirmed against erythromycin (100%), whereas no isolates showed resistance against ciprofloxacin. The observed practices coupled with the presence of multidrug-resistant E. coli in the slaughterhouses presents a possible risk of pork contamination with multidrug-resistant E. coli presenting a potential risk of causing foodborne illnesses among pork consumers in Uganda. The current findings could justify active surveillance of antimicrobial resistance among food animals and provides basis for monitoring the quality of pork products to ensure food safety.

The Carriage of Escherichia coli Resistant to Antibiotics in Healthy Populations in Shanghai

Healthy populations represent the largest reservoir of bacteria resistant to antibiotics.We investigated the resistance of Escherichta coli to 12 antibiotics in fecal samples from untreated healthy populations in Shanghai, China by using Kirby-Bauer (K-B) method. The results showed that: (i) All subjects carried resistant strains of Escherichta coli. (ii) The carriage rates of Escherichta coli resistant to various antibiotics were different, less than 10 % to amikacin and 30 % to 100% to others. (iii) In the elder children group aged 10-11 years, the percentages of stralns resistant to gentamicin, streptomycin, chloramphenicol, tetracycline, trimethoprim, and sulfamethoxazole were significantly lower than those in the younger group aged 5-6 years. In the adult group, the percentages of strains resistant to ampicillin, piperacillin, arnikacin, streptomycin, chloramphenicol, tetracycline, trimethoprim, and sulfamethoxarole were significantly lower than those in the elder children group. (iv) The number of strains resistant to five or more antibiotics accounted for 31. 8 % in the younger children group, 23. 7 % in the elder children group,and 12. 1 % in the adult group. These findings suggest that all healthy people in Shanghal carry resistant strains of Escherichta coli in the intestine. The younger the populations, the higher the level of resistance of fecal Escherichta coli to antibiotics. Improvement of health behaviors and environmental sanitation and rational use of antibiotics could remarkedly decrease the resistant level of bacteria

In Vitro Antibacterial Activity of Galla Chinensis Combined with Different Antibacterial Drugs against Carbapenem-Resistant E.Coli

Objective:To evaluate the antibacterial effects of meropenem and levofloxacin respectively combined with Galla chinensis on carbapenem-resistant Escherichia coli in vitro.Methods:The protocol was designed with checkerboard method and the carbapenem-resistant E.coli was isolated in our hospital.The minimum inhibitory concentrations(MICs)of G.chinensis alone and combined with 2 antimicrobial agents against carbapenem-resistant E.coli were determined by broth dilution method and the fractional inhibitory concentration index(FICI)was calculated according to MICs results.Result:the combined use of G.chinensis and meropenem(or levofloxacin)significantly decreased both MIC50 and MIC90;After the combination of G.chinensis and meropenem,the synergistic effect was 86.7%,and the additive effect was 13.3%,no irrelevant and antagonistic effects.After combined use of G.chinensis and levofloxacin,the synergistic effect was 66.7%,and the additive effect was 33.3%.No irrelevant and antagonistic effects.Conclusion:Galla chinensis combined with meropenem or levofloxacin has synergistic and additive antibacterial effect,with certain combined antibacterial activity.

Multidrug Resistant Pattern and Plasmid Detection of Escherichia coli from Various Sources within the University of Port Harcourt

Multi-drug resistance (MDR) in Enterobacteriaceae poses critical public health threat in Nigeria and the global world. This resistant mechanism might be plasmid mediated or chromosomal. Escherichia coli are Gram negative pathogen with a global distribution rate. The study was carried out to determine MDR and plasmid profiling of E. coli isolates from urine, feaces and poultry litter. The samples were cultured on eosine methylene blue agar and incubated for 24 hours at 37&#176;C. Results obtained showed a percentage prevalence of 30% for the urine samples which were the most prevalent, while the prevalence of E. coli from the feacal and poultry litter was 8% and 28% respectively. Identified E. coli were screened for antibiotic susceptibility by Kirby Bauer diffusion method. The results on susceptibility of E. coli to tested antibiotics before plasmid curing showed 100% resistance to cefuroxime and augumentin, while 75% resistance was observed in gentamicine, ciprofloxacin and ofloxacine. Cefixime and cefdazidime resistance were 62.5% on E. coli and the least resistance was observed in nitrofurantion (25%). The poultry litter and urine isolates recorded lower resistance level to antibiotics, compared to the feacal isolates. After plasmid curing the percentage of resistance reduced. The only antibiotics that responded positively was nitrofurantion, with high sensitivity of 87% for feacal isolate, 100% for urine isolates, and 78% for poultry litter isolates after plasmid curing. Twenty (20) of the thirty seven (37) isolates were still resistant to more than two antibiotics after the plasmid curing. Of the twenty isolates, 18 (90%) were found to harbor single plasmid, while 2 (10%) did not possess plasmid. This study concludes that nitrofurantion was the most effective antibiotics on Escherichia coli and plasmids were responsible partly for resistance.

Selection of Phage-resistant Strains from Escherichia coli glyA Genetic Engineering Bacteria

[ Objective] This study aimed to select E. coli strains with phage-resistance. [ Method] Phage-resistant strains of E. coli glyA genetic engineering bacteria were selected by phage induction and UV-coupling phage induction. [ Result] By phage induction, 20 strains with stable resistance were selected from the 24 phage-resistant strains, only one strain showed better growth condition than the original strains, but the enzymatic activities of the 20 strains were all lower than the original strains; 41 phage-resistant strains were selected by UV-coupling phage induction, 39 strains of which had better stability, including 7 strains that showed better growth conditions than the original strains and two strains had higher enzymatic activities than the original strains. [ Conclusion] UV-coupling phage induction is a suitable method to select phage-resistant strains from Ecoli genetic engineering bacteria.

Characteristics of colistin-resistant Escherichia coli from pig farms in Central China

The emergence and dissemination of colistin resistance in Enterobacterioceae mediated by plasmid-borne mcr genes in recent years now pose a threat to public health.In this study,we isolated and characterized colistin-resistant and for mcr-positive£coli from pig farms in Central China.Between 2018 and 2019,594 samples were collected and recovered 445 E.coli isolates.Among them,33 with colistin resistance phenotypes and 37 that were positive for mcr genes were identified,including 34 positive for mcr-1,one positive for mcr-3,and two positive for both mcr-1 and mcr-3.An insertion of nine bases("CTGGATACG")into mcr-7 in four mcr-positive isolates led to gene dysfunction,and therefore did not confer the colistin resistance phenotype.Antimicrobial susceptibility testing revealed that 37 mcr-positive isolates showed severe drug resistance profiles,as 50% of them were resistant to 20 types of antibiotics.Multilocus sequence typing revealed a heterogeneous group of sequence types in mcr-positive isolates,among which ST10(5/37),ST156(5/37),and 5T617(4/37)were the predominant types.Plasmid conjugation assays showed that mcr-carrying plasmids of 25 mcr-positive isolates were conjugated with£coli recipient,with conjugation frequencies ranging from 1.7 × 10^(-6) to 4.1 × 10^(-3) per recipient.Conjugation of these mcr genes conferred a colistin resistance phenotype upon the recipient bacterium.PCR typing of plasmids harbored in the 25 transconjugants determined six types of plasmid replicons,including lncX4(14/25),FrepB(4/25),Incl2(3/25),lncHI2(2/25),FIB(1/25),and Inch(1/25).This study contributes to the current understanding of antibiotic resistance and molecular characteristics of colistin-resistant£coli in pig farms.

How Growth Ability of Multidrug-Resistant Escherichia coli Is Affected by Abiotic Stress Factors

The ability of multidrug-resistant Escherichia coli to adapt and grow in a wide range of different environmental conditions may be crucial to the global spread of antimicrobial resistance. The aim of this study was to evaluate the survival ability of 54 multidrug-resistant E. coli strains, isolated from three different biotopes (clinical setting, gull intestine, river water) when subjected to variations in pH (from 3 to 11) and salinity (from 0.5% to 6% of NaCl) and to nutrient deprivation. The growth of each isolate as well as of a reference strain was assessed during 168 h in every varying condition. Slight variations in the growth ability under some abiotic stress factors were recorded among the isolates from the different biotopes. Multidrug-resistant isolates from gull feces were found to be the more tolerant to environmental abiotic changes, while isolates from river water were the less tolerant. In addition, it was notorious that the carriage of antimicrobial resistance has a clear fitness cost in comparison with the susceptible (reference) strain, highlighting the necessity of reducing the selective pressure exerted by antibiotics. This study underlines the ecological hardness of multidrug-resistant E. coli isolates with a consequent ability to reach and colonize new host and environments.