scholarly journals Surveillance of antimicrobial-resistant Escherichia coli in Sheltered dogs in the Kanto Region of Japan

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Akihisa Hata ◽  
Noboru Fujitani ◽  
Fumiko Ono ◽  
Yasuhiro Yoshikawa
Keyword(s):  
Escherichia Coli ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Resistant Bacteria ◽  
Animal Shelters ◽  
E Coli ◽  
Chiba Prefecture ◽  
Shelter Dogs ◽  
Kanagawa Prefecture ◽  
Kanto Region

AbstractThere is a lack of an established antimicrobial resistance (AMR) surveillance system in animal welfare centers. Therefore, the AMR prevalence in shelter dogs is rarely known. Herein, we conducted a survey in animal shelters in Chiba and Kanagawa prefectures, in the Kanto Region, Japan, to ascertain the AMR status of Escherichia coli  (E. coli) prevalent in shelter dogs. E. coli was detected in the fecal samples of all 61 and 77 shelter dogs tested in Chiba and Kanagawa, respectively. The AMR was tested against 20 antibiotics. E. coli isolates derived from 16.4% and 26.0% of samples from Chiba and Kanagawa exhibited resistance to at least one antibiotic, respectively. E. coli in samples from Chiba and Kanagawa prefectures were commonly resistant to ampicillin, piperacillin, streptomycin, kanamycin, tetracycline, and nalidixic acid; that from the Kanagawa Prefecture to cefazolin, cefotaxime, aztreonam, ciprofloxacin, and levofloxacin and that from Chiba Prefecture to chloramphenicol and imipenem. Multidrug-resistant bacteria were detected in 18 dogs from both regions; β-lactamase genes (blaTEM, blaDHA-1, blaCTX-M-9 group CTX-M-14), quinolone-resistance protein genes (qnrB and qnrS), and mutations in quinolone-resistance-determining regions (gyrA and parC) were detected. These results could partially represent the AMR data in shelter dogs in the Kanto Region of Japan.

scholarly journals Virulence and plasmidic resistance determinants of Escherichia coli isolated from municipal and hospital wastewater treatment plants

2014 ◽  
Vol 13 (2) ◽  
pp. 311-318 ◽  
Author(s):  
Vera Calhau ◽  
Catarina Mendes ◽  
Angelina Pena ◽  
Nuno Mendonça ◽  
Gabriela Jorge Da Silva
Keyword(s):  
Escherichia Coli ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plants ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Diffusion Method ◽  
Resistant Bacteria ◽  
Hospital Wastewater ◽  
Aminoglycoside Resistance ◽  
E Coli

Escherichia coli is simultaneously an indicator of water contamination and a human pathogen. This study aimed to characterize the virulence and resistance of E. coli from municipal and hospital wastewater treatment plants (WWTPs) in central Portugal. From a total of 193 isolates showing reduced susceptibility to cefotaxime and/or nalidixic acid, 20 E. coli with genetically distinct fingerprint profiles were selected and characterized. Resistance to antimicrobials was determined using the disc diffusion method. Extended spectrum β-lactamase and plasmid-mediated quinolone resistance genes, phylogroups, pathogenicity islands (PAIs) and virulence genes were screened by polymerase chain reaction (PCR). CTX-M producers were typed by multilocus sequence typing. Resistance to beta-lactams was associated with the presence of blaTEM,blaSHV, blaCTX-M-15 and blaCTX-M-32. Plasmid-mediated quinolone resistance was associated with qnrA, qnrS and aac(6′)-Ib-cr. Aminoglycoside resistance and multidrug-resistant phenotypes were also detected. PAI IV536, PAI IICFT073, PAI II536 and PAI ICFT073, and uropathogenic genes iutA, papAH and sfa/foc were detected. With regard to the clinical ST131 clone, it carried blaCTX-M-15, blaTEM-type, qnrS and aac(6′)-lb-cr; IncF and IncP plasmids, and virulence factors PAI IV536, PAI ICFT073, PAI IICFT073, iutA, sfa/foc and papAH were identified in the effluent of a hospital plant. WWTPs contribute to the dissemination of virulent and resistant bacteria in water ecosystems, constituting an environmental and public health risk.

scholarly journals In vitro activity of antimicrobial peptide CDP-B11 alone and in combination with colistin against colistin-resistant and multidrug-resistant Escherichia coli

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaitlin S. Witherell ◽  
Jason Price ◽  
Ashok D. Bandaranayake ◽  
James Olson ◽  
Douglas R. Call
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Peptide ◽  
Membrane Integrity ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Multidrug Resistant Bacteria ◽  
E Coli ◽  
Minimal Media

AbstractMultidrug-resistant bacteria are a growing global concern, and with increasingly prevalent resistance to last line antibiotics such as colistin, it is imperative that alternative treatment options are identified. Herein we investigated the mechanism of action of a novel antimicrobial peptide (CDP-B11) and its effectiveness against multidrug-resistant bacteria including Escherichia coli #0346, which harbors multiple antibiotic-resistance genes, including mobilized colistin resistance gene (mcr-1). Bacterial membrane potential and membrane integrity assays, measured by flow cytometry, were used to test membrane disruption. Bacterial growth inhibition assays and time to kill assays measured the effectiveness of CDP-B11 alone and in combination with colistin against E. coli #0346 and other bacteria. Hemolysis assays were used to quantify the hemolytic effects of CDP-B11 alone and in combination with colistin. Findings show CDP-B11 disrupts the outer membrane of E. coli #0346. CDP-B11 with colistin inhibits the growth of E. coli #0346 at ≥ 10× lower colistin concentrations compared to colistin alone in Mueller–Hinton media and M9 media. Growth is significantly inhibited in other clinically relevant strains, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. In rich media and minimal media, the drug combination kills bacteria at a lower colistin concentration (1.25 μg/mL) compared to colistin alone (2.5 μg/mL). In minimal media, the combination is bactericidal with killing accelerated by up to 2 h compared to colistin alone. Importantly, no significant red blood hemolysis is evident for CDP-B11 alone or in combination with colistin. The characteristics of CDP-B11 presented here indicate that it can be used as a potential monotherapy or as combination therapy with colistin for the treatment of multidrug-resistant infections, including colistin-resistant infections.

scholarly journals Retail Chicken Carcasses as a Reservoir of Antimicrobial- Resistant Escherichia coli

2020 ◽  
Author(s):  
Nahla Omer Eltai ◽  
Hadi M. Yassine ◽  
Sara H. Al-Hadidi ◽  
Tahra ElObied ◽  
Asmaa A. Al Thani ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Growth Promotion ◽  
Multidrug Resistant ◽  
Chicken Meat ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Inappropriate Use ◽  
Esbl Producers

The dissemination of antimicrobial resistance (AMR) bacteria has been associated with the inappropriate use of antibiotics in both humans and animals and with the consumption of food contaminated with resistant bacteria. In particular, the use of antibiotics as prophylactic and growth promotion purposes in food-producing animals has rendered many of the antibiotics ineffective. The increased global prevalence of AMR poses a significant threat to the safety of the world’s food supply. Objectives: This study aims at determining the prevalence of antibiotic-resistant Escherichia coli (E. coli) isolated from local and imported retail chicken meat in Qatar. Methodology: A total of 270 whole chicken carcasses were obtained from three different hypermarket stores in Qatar. A total of 216 E. coli were isolated and subjected to antibiotic susceptibility testing against 18 relevant antibiotics using disc diffusion and micro- dilution methods. Furthermore, extended-spectrum β-lactamase (ESBL) production was determined via a double-disc synergetic test. Isolates harboring colistin resistance were confirmed using multiplex-PCR and DNA sequencing. Results: Nearly 89% (192/216) of the isolates were resistant to at least one antibiotics. In general, isolates showed relatively higher resistance to sulfamethoxazole (62%), tetracycline (59.7%), ampicillin and trimethoprim (52.3%), ciprofloxacin (47.7%), cephalothin, and colistin (31.9%). On the other hand, less resistance was recorded against amoxicillin/clavulanic acid (6%), ceftriaxone (5.1%), nitrofurantoin (4.2%) and piperacillin/tazobactam (4.2%), cefepime (2.3%), meropenem (1.4%), ertapenem (0.9%), and amikacin (0.9%). Nine isolates (4.2%) were ESBL producers. Furthermore, 63.4% were multidrug-resistant (MDR). The percentage of MDR, ESBL producers, and colistin-resistant isolates was significantly higher among local isolates compared to imported chicken samples. Conclusion: We reported a remarkably high percentage of the antibiotic-resistant E. coli in chicken meat sold at retail in Qatar. The high percentage of MDR and colistin isolates is troublesome to the food safety of raw chicken meat and the potential of antibiotic resistance spread to public health. Our findings support the need for the implementation of one health approach to address the spread of antimicrobial resistance and the need for a collaborative solution.

scholarly journals Mutational Analysis of Quinolone-Resistant Determining Region gyrA and parC Genes in Quinolone-Resistant ESBL-Producing E. Coli

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
Hairul Aini Hamzah ◽  
Rahmatullah Sirat ◽  
Mohammed Imad A. Mustafa Mahmud ◽  
Roesnita Baharudin
Keyword(s):  
Mutational Analysis ◽  
Single Point ◽  
Point Mutations ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Resistant Bacteria ◽  
Single Point Mutation ◽  
Phenotypic Resistance ◽  
Drug Effectiveness ◽  
E Coli

 Introduction: Co-resistance to quinolones among extended spectrum β[1]lactamase (ESBL)-producing E. coli commonly occurs in clinical settings. Quinolones act on DNA gyrase and DNA topoisomerase enzymes, which are coded by gyrA and parC genes, thus any mutation to the genes may affect the drug effectiveness. The objective of the study was to characterize gyrA and parC genes in quinolone-resistant E. coli isolates and correlated the mutations with their phenotypic resistance. Materials and Methods: Thirty-two quinolone-resistant (QR) and six quinolone-sensitive (QS) ESBL-E. coli isolates were identified by antibiotic susceptibility and minimum inhibitory concentration tests. Bioinformatics analysis were conducted to study any mutations occurred in the genes and generate their codon compositions. Results: All the QR ESBL-E. coli isolates were identified as multidrug-resistant bacteria. A single point mutation in the quinolone resistance-determining region (QRDR) of gyrA, at codon 83, caused the substitution amino acid Ser83Leu. It is associated with a high level of resistance to nalidixic acid. However, double mutations Ser83Leu and Asp87Asn in the same region were significantly linked to higher levels of resistance to ciprofloxacin. Cumulative point mutations in gyrA and/or in parC were also correlated significantly (p<0.05) to increased resistance to ciprofloxacin. Conclusion: Together, the findings showed that the mutations in gyrA and parC genes handled the institution of intrinsic quinolone resistance in the ESBL-E. coli isolates. Thus, vigilant monitoring for emergence of new mutation in resistance genes may give an insight into dissemination of QR ESBL-E. coli in a particular region.

scholarly journals Emergence of high multidrug-resistant Escherichia coli isolates from neonates with infection

2020 ◽  
Author(s):  
Dan Wu ◽  
Yijun Ding ◽  
Jinjing Zhang ◽  
Kaihu Yao ◽  
Wei Gao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Multidrug Resistance ◽  
Clavulanic Acid ◽  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
E Coli ◽  
Mueller Hinton ◽  
Mueller Hinton Agar ◽  
Amoxicillin Clavulanic Acid

Abstract Background Escherichia coli (E.coli) rank one of the most common pathogens that can cause neonatal infections. The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in newborn with infection. The purpose of this study was to describe the antibiotic resistance and multidrug-resistance of E.coli isolated from neonates with infection.Methods The antimicrobial susceptibility testing of the E. coli strains to selected antibiotics was assessed with the E-test technique on the Mueller-Hinton agar. The antimicrobials tests were included ceftazidime, cefuroxime, cefatriaxone, amoxicillin, amoxicillin-clavulanic acid, cefoperazone - sulbactam, meropenem, gentamicin, ciprofloxacin and sulfonamides. The minimal inhibitory concerntration (MIC) values of the antimicrobial agents selected for this study was determined by an agar dilution technique on Mueller-Hinton agar according to the Clinical and Laboratory Standards Institute recommendations. Results A total of 100 E. coli strains was isolated from phlegm (n = 78), blood (n = 10), cerebrospinal fluid (n = 5), and umbilical discharge (n = 7) of neonates hospitalized at Beijing Children’s Hospital. The highest resistance rate of E.coli was found in amoxicillin at 85%, followed by cefuroxime 65%, and cefatriaxone 60%, respectively. 6% and 5% of all isolates were resistant to amoxicillin/clavulanic acid and cefoperazone -sulbactam merely. The resistance rates to ceftazidime, gentamicin, ciprofloxacin and sulfonamides were 31%, 20%, 33%, 47%, respectively. All the isolates were susceptible to meropenem. Multidrug resistance was defined in E.coli as resistance to at least three antibiotic families. About 26% (26/100) of all the E.coli isolates were multidrug-resistant. The detection rate of ESBL-Producing E. coli was 55%. The rate in E. coli isolates from phlegm was higher than aseptic humoral. The difference was statistically significant (P < 0.05). It is worth noting that the majority of the isolates were also resistant to non-β-lactam antimicrobial agents, but the resistant rates were significantly lower than extended-spectrum β-lactamases.Conclusions: Multi-drug-resistant E.coli has become a thorny problem in clinical treatment. It is necessary to monitor E. coli resistance.

scholarly journals Quinolone resistance (qnrA) gene in isolates of Escherichia coli collected from the Al-Hillah River in Babylon Province, Iraq

Pharmacia ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 1-7
Author(s):  
Hawraa Mohammed Al-Rafyai ◽  
Mourouge Saadi Alwash ◽  
Noor Salman Al-Khafaji
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Antibiotic Resistance Genes ◽  
Quinolone Resistance ◽  
Resistant Bacteria ◽  
Global Public Health ◽  
Phenotypic Resistance ◽  
E Coli ◽  
Potential Reservoir ◽  
Public Health Hazards

Aquatic environment contamination remains a foremost global public health hazards, and symbolizes a significant reservoir of releasing antibiotic resistant bacteria. The survival of Escherichia coli in aquatic environments serves as a potential reservoir of antibiotic resistance, encompassing but not restricted to a plasmid-mediated quinolone resistance (PMQR) mechanism. The current study aimed to detect the presence of the PMQR-qnrA gene in quinolone-resistant E. coli isolates. Sixty-one waterborne E. coli with known phylogroups/subgroups isolated from the Al-Hillah River in Babylon Province, Iraq, were screened for the phenotypic resistance to third-generation quinolones (levofloxacin and ofloxacin) and were further analysed for the presence of the qnrA gene using polymerase chain reaction (PCR). Fifty-seven (93.4%) of 61 E. coli isolates were levofloxacin-resistant, and 55 (90.2%) were ofloxacin-resistant. Among the 57 quinolone-resistant E. coli, 40 (65.57%) isolates were found to carry the PMQR-qnrA gene. Among the 40 qnrA-positive E. coli, 22 (36.1%) isolates were in phylogroup B2, followed by 8 (13.1%) isolates in phylogroup D, 6 (9.8%) isolates in phylogroup B1, and 4 (6.6%) isolates in phylogroup A. The presence of the PMQR-qnrA gene in E. coli belonging to phylogroup B2 and D reflects the need for routine monitoring of antibiotic resistance genes (ARGs) in the Al-Hillah River.

scholarly journals Risk factors for fecal carriage of multidrug-resistant Escherichia coli in a college community: a penalized regression model

2020 ◽  
Author(s):  
Yuan Hu ◽  
Julia Rubin ◽  
Kaitlyn Mussio ◽  
Lee W. Riley
Keyword(s):  
Risk Factors ◽  
Escherichia Coli ◽  
Logistic Regression ◽  
Penalized Regression ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
E Coli ◽  
College Community ◽  
Fecal Carriage

AbstractBackgroundBacterial antimicrobial resistance is a serious global public health threat. Intestinal commensal drug-resistant bacteria have been suggested as an important reservoir of antimicrobial resistant genes (ARGs), which may be acquired via food. We aimed to identify risk factors associated with fecal carriage of drug-resistant commensal Escherichia coli (E. coli) among healthy adults focused on their dietary habit.MethodsWe conducted a cross-sectional study targeting healthy adult volunteers in a college community. Fecal samples and questionnaires were obtained from 113 volunteers. We conducted backward elimination logistic regression and least absolute shrinkage and selection (LASSO) methods to identify risk factors.ResultsWe analyzed responses from 81 of 113 volunteers who completed the questionnaire. The logistic regression and LASSO methods identified red meat consumption to be associated with increased risk (OR = 6.13 [1.83-24.2] and 1.82, respectively) and fish consumption with reduced risk (OR = 0.27 [0.08-0.85] and 0.82) for the carriage of multidrug-resistant E. coli, adjusted for gender, employment status, frequently-used supermarket, and previous travel.ConclusionsDietary habits are associated with the risk of fecal carriage of multidrug-resistant E. coli. This study supports the growing evidence that food may be an important source of ARGs present in human commensal E. coli.

scholarly journals Carbapenem and colistin-resistant bacteria in North Lebanon: Coexistence of mcr-1 and NDM-4 genes in Escherichia coli

2021 ◽  
Vol 15 (07) ◽  
pp. 934-342
Author(s):  
Charbel Al-Bayssari ◽  
Tania Nawfal Dagher ◽  
Samar El Hamoui ◽  
Fadi Fenianos ◽  
Nehman Makdissy ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Resistance Genes ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Ionization Time ◽  
E Coli ◽  
Flight Mass Spectrometry ◽  
Carbapenem Resistant ◽  
The Matrix

Introduction: The increasing incidence of infections caused by multidrug-resistant bacteria is considered a global health problem. This study aimed to investigate this resistance in Gram-negative bacteria isolated from patients hospitalized in North-Lebanon. Methodology: All isolates were identified using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antibiotic susceptibility testing was achieved using disk diffusion, E-test and Broth microdilution methods. Phenotypic detection of carbapenemase was carried out using the CarbaNP test. RT-PCR, standard-PCR and sequencing were performed to detect resistance genes and oprD gene. Conjugal transfer was carried out between our isolates and Escherichia coli J53 to detect the genetic localization of resistance genes. MLST was conducted to determine the genotype of each isolate. Results: Twenty-three carbapenem-resistant Enterobacterales of which eight colistin-resistant Escherichia coli, and Twenty carbapenem-resistant Pseudomonas aeruginosa were isolated. All isolates showed an imipenem MIC greater than 32 mg/mL with MICs for colistin greater than 2 mg/L for E. coli isolates. All the Enterobacterales isolates had at least one carbapenemase-encoding gene, with E. coli isolates coharboring blaNDM-4 and mcr-1 genes. Moreover, 16/20 Pseudomonas aeruginosa harbored the blaVIM-2 gene and 18/20 had mutations in the oprD gene. MLST revealed that the isolates belonged to several clones. Conclusions: We report here the first description in the world of clinical E. coli isolates coharboring blaNDM-4 and mcr-1 genes, and K. pneumoniae isolates producing NDM-6 and OXA-48 carbapenemases. Also, we describe the emergence of NDM-1-producing E. cloacae in Lebanon. Screening for these isolates is necessary to limit the spread of resistant microorganisms in hospitals.

scholarly journals 611. Fosfomycin Resistance of Multidrug-Resistant Escherichia coli and Mechanisms of Fosfomycin Resistance

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S285-S285
Author(s):  
Hyeri Seok ◽  
Ji Hoon Jeon ◽  
Hee Kyoung Choi ◽  
Won Suk Choi ◽  
Dae Won Park ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Resistance Rate ◽  
Coli Strain ◽  
Resistant Bacteria ◽  
E Coli ◽  
Broth Microdilution Method ◽  
Fosfomycin Resistance

Abstract Background Fosfomycin is one of the antibiotics that may be a candidate for the next-generation antimicrobial agents againt multidrug-resistant bacteria. To date, it is known that the resistance rate is not high for Escherichia coli. However, it is necessary to update the fosfomycin resistance rates in E. coli according to the studies that extended spectrum β-lactamase (ESBL) producing E. coli strains are highly resistance to fosfomycin. We evaluated the resistance rate of fosfomycin, the resistant mechanism of fosfomycin in E. coli, and the activity of fosfomycin against susceptible and resistant strains of E. coli. Methods A total of 283 clinical isolates was collected from patients with Escherichia coli species during the period of January 2018 to June 2018, in three tertiary hospitals of Republic of Korea. In vitro antimicrobial susceptibility tests were performed in all E. coli isolates using the broth microdilution method according to the Clinical and Laboratory Standard Institute (CLSI). Multilocus sequence typing (MLST) of the Oxford scheme was conducted to determine the genotypes of E. coli isolated. Fosfomycin genes were investigated for all fosfomycin-resistant E. coli strains. Results The overall resistance rate to fosfomycin was 10.2%, compared with 53.4%, 46.3%, 41.3%, 31.1%, 10.6%, 2.5%, and 2.1% for ciprofloxacin, cefixime, cefepime, piperacillin/tazobactam, colistin, ertapenem, and amikacin, respectively. The 29 fosfomycin-resistant isolates did not show a clonal pattern on the phylogenetic tree. MurA and glp genes were identified in all strains. FosA3 were identified in two strains and uhp gene were identified in 4 strains. In time-kill curve studies, fosfomycin was more bactericidal than cefixime against all sensitive E. coli strain. Morever, fosfomycin was more bactericidal than piperacillin/tazobactam against ESBL-producing E. coli strain. Conclusion The resistant rate of fosfomycin to E. coli is still low. Fosfomycin was active against E. coli including ESBL producing strains. Disclosures All authors: No reported disclosures.

scholarly journals Genomic Analysis of a Novel Phage Infecting the Turkey Pathogen Escherichia coli APEC O78 and Its Endolysin Activity

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1034
Author(s):  
Sangsang Deng ◽  
Qiang Xu ◽  
Yajuan Fu ◽  
Leiqin Liang ◽  
Yan Wu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Annotation ◽  
Gc Content ◽  
Multidrug Resistant ◽  
Dimensional Structure ◽  
Resistant Bacteria ◽  
Local Alignment ◽  
Glycoside Hydrolase Family ◽  
E Coli ◽  
Tract Infections

Due to the increasing spread of multidrug-resistant (MDR) bacteria, phage therapy is considered one of the most promising methods for addressing MDR bacteria. Escherichia coli lives symbiotically in the intestines of humans and some animals, and most strains are beneficial in terms of maintaining a healthy digestive tract. However, some E. coli strains can cause serious zoonotic diseases, including diarrhea, pneumonia, urinary tract infections, and hemolytic uremic syndrome. In this study, we characterized a newly isolated Myoviridae phage, vB_EcoM_APEC. The phage vB_EcoM_APEC was able to infect E. coli APEC O78, which is the most common MDR E. coli serotype in turkeys. Additionally, the phage’s host range included Klebsiella pneumoniae and other E. coli strains. The genome of phage vB_EcoM_APEC (GenBank accession number MT664721) was 35,832 bp in length, with 52 putative open reading frames (ORFs) and a GC content of 41.3%. The genome of vB_EcoM_APEC exhibited low similarity (79.1% identity and 4.0% coverage) to the genome of Acinetobacter phage vB_AbaM_IME284 (GenBank no. MH853787.1) according to the nucleotide Basic Local Alignment Search Tool (BLASTn). Phylogenetic analysis revealed that vB_EcoM_APEC was a novel phage, and its genome sequence showed low similarity to other available phage genomes. Gene annotation indicated that the protein encoded by orf11 was an endolysin designated as LysO78, which exhibited 64.7% identity (91.0% coverage) with the putative endolysin of Acinetobacter baumannii phage vB_AbaM_B9. The LysO78 protein belongs to glycoside hydrolase family 19, and was described as being a chitinase class I protein. LysO78 is a helical protein with 12 α-helices containing a large domain and a small domain in terms of the predicted three-dimensional structure. The results of site-directed mutagenesis indicated that LysO78 contained the catalytic residues E54 and E64. The purified endolysin exhibited broad-spectrum bacteriolytic activity against Gram-negative strains, including the genera Klebsiella, Salmonella, Shigella, Burkholderia, Yersinia, and Pseudomonas, as well as the species Chitinimonas arctica, E. coli, Ralstonia solanacearum, and A. baumannii. An enzymatic assay showed that LysO78 had highly lytic peptidoglycan hydrolases activity (64,620,000 units/mg) against E. coli APEC O78, and that LysO78 had lytic activity in the temperature range of 4–85 °C, with an optimal temperature of 28 °C and optimal pH of 8.0, and was active at pH 3.0–12.0. Overall, the results suggested that LysO78 might be a promising therapeutic agent for controlling MDR E. coli APEC O78 and nosocomial infections caused by multidrug-resistant bacteria.

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