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AbstractThe Grunow–Finke epidemiological assessment tool (GFT) has several limitations in its ability to differentiate between natural and man‐made epidemics. Our study aimed to improve the GFT and analyze historical epidemics to validate the model. Using a gray relational analysis (GRA), we improved the GFT by revising the existing standards and adding five new standards. We then removed the artificial weights and final decision threshold. Finally, by using typically unnatural epidemic events as references, we used the GRA to calculate the unnatural probability and obtain assessment results. Using the advanced tool, we conducted retrospective and case analyses to test its performance. In the validation set of 13 historical epidemics, unnatural and natural epidemics were divided into two categories near the unnatural probability of 45%, showing evident differences (p < 0.01) and an assessment accuracy close to 100%. The unnatural probabilities of the Ebola virus disease of 2013 and Middle East Respiratory Syndrome of 2012 were 30.6% and 36.1%, respectively. Our advanced epidemic assessment tool improved the accuracy of the original GFT from approximately 55% to approximately 100% and reduced the impact of human factors on these outcomes effectively.

Kaiying Wang,1,2,* Peihan Li,1,2,* Jinhui Li,2,* Xiaofeng Hu,2,* Yanfeng Lin,1,2 Lang Yang,1,2 Shaofu Qiu,2 Hui Ma,*,3 Peng Li,2 Hongbin Song2 1College of Military Medicine, Academy of Military Sciences, Beijing, People's Republic of China; 2Center for Disease Control and Prevention of PLA, Beijing, People's Republic of China; 3The Sixth Medical Center of PLA General Hospital, Beijing, People's Republic of China*These authors contributed equally to this workCorrespondence: Peng Li; Hongbin Song Tel/ Fax +86-10-66948475Email jiekenlee@126.com; hongbinsong@263.netBackground: The New Delhi metallo-β-lactamase-1 (NDM-1)-positive plasmid and its variants pose daunting threats to public health. Hospital sewage was considered as an important reservoir of antibiotic genes. Numerous and diverse taxa of multidrug-resistant (MDR) bacteria carrying NDM-1-positive plasmids have been identified during routine surveillance of hospital sewage. We herein report a carbapenem-resistant Acinetobacter towneri strain AeBJ009 with an NDM-1-positive plasmid isolated from hospital sewage.Materials and Methods: Bacteria were isolated from cultures of hospital sewage and identified by using the Vitek 2 compact system and 16S rRNA sequencing. The blaNDM-1 gene was amplified and confirmed by sequencing. Antimicrobial susceptibility testing was performed using AST-GN14 on the Vitek2 compact system. In addition, the blaNDM-1 gene was located by Southern blotting. Conjugation experiment and whole-genome sequencing were performed for further analysis.Results: Strain AeBJ009 was isolated from hospital sewage and identified as A. towneri. Antimicrobial susceptibility testing revealed an MDR phenotype. Pulsed-field gel electrophoresis and Southern blotting showed that strain AeBJ009 carries three plasmids and that blaNDM-1 is located on the 47kb plasmid pNDM-AeBJ009. However, the conjugation experiment to transfer pNDM-AeBJ009 to Escherichia coli strain J53 was unsuccessful. Whole-genome sequencing found that pNDM-AeBJ009 contains a Tn 125 element carrying blaNDM-1. The ble gene downstream of blaNDM-1 displayed a single-nucleotide polymorphism compared to its homologue on plasmid pM131_NDM1. BLAST analysis using the Comprehensive Antibiotic Resistance Database identified no gene polymorphisms with 100% identity to our ble variant.Conclusion: The A. towneri strain AeBJ009 exhibiting an extended spectrum of antibiotic resistance was isolated from hospital sewage and may potentially exacerbate the risk of MDR bacterial infections. The prevention of nosocomial infections due to drug-resistant bacteria will require enhanced monitoring and control of MDR pathogens in environmental reservoirs.Keywords: NDM-1, ble, Acinetobacter towneri, drug resistance

Peihan Li, 1, 2,* Yanfeng Lin, 1, 2,* Xiaofeng Hu, 2,* Yuqi Liu, 1, 2 Mei Xue, 3 Lang Yang, 1, 2 Jinhui Li, 2 Lei Zha, 2 Kaiying Wang, 1 Kezong Qi, 3 Shaofu Qiu, 2 Peng Li, 2 Hongbin Song 2 1Academy of Military Medical Sciences, Academy of Military Sciences, Beijing, People's Republic of China; 2Center for Disease Control and Prevention of PLA, Beijing, People's Republic of China; 3Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Anhui, People's Republic of China*These authors contributed equally to this workCorrespondence: Peng Li; Hongbin SongCenter for Disease Control and Prevention of PLA, 20 DongDa Street, Fengtai District, Beijing 100071, People's Republic of ChinaTel/Fax +86-10-66948475Email jiekenlee@126.com; hongbinsong@263.netPurpose: Carbapenem-resistant Enterobacter cloacae complex has been reported worldwide and becomes a new challenge for clinical management. The present study was to characterize the IncX3 plasmid encoding blaNDM-1 and blaSHV-12 gene in E. hormaechei sequence.Materials and Methods: EcHK001 was recovered from the sputum sample of a patient. Species identification and antimicrobial susceptibility testing were performed using the VITEK 2 system, while further classification was carried out by hsp60 typing. The presence of NDM-1 was detected by PCR and sequencing. Conjugation experiments and southern blotting were carried out to determine the transferability of the NDM-1-carrying plasmid. Whole-genome sequencing and analysis were conducted to better understand the molecular characteristics of the multi-drug resistant isolate.Results: Strain EcHK001 was classified as E. hormaechei of new sequence type 1000. Multiple drug-resistant genes were detected. The blaNDM-1 and blaSHV-12 genes were located on a self-transferable IncX3 plasmid. Synonymous mutations were identified in the genes encoding TEM-1 and ACT-17. Phylogenetic analysis indicated that EcHK001 clustered into a different clade from domestic strains.Conclusion: The rapid spread of the recurrent IncX3 plasmid highlights the need for continuous surveillance of the NDM-1 dissemination. The presence of mutations in existing carbapenem-resistant genes may generate potential new variants and raise serious challenges for clinical treatment.Keywords: multidrug-resistant, NDM-1, SHV-12, enterobacter hormaechei

The rapid emergence of multidrug resistant Salmonella is a global public-health concern as outbreaks in recent years have mostly been caused by multidrug resistant strains. Here, we evaluated an outbreak in China caused by multidrug resistant Salmonella enterica serovar Typhimurium (S. Typhimurium) by employing an epidemiological and laboratory investigation using conventional methods and whole genome sequencing (WGS). Eleven of the 12 people who participated in a banquet showed gastrointestinal symptoms, and 8S. Typhimurium strains were recovered. Isolated outbreak strains showed multidrug resistance (MDR), and decreased susceptibility to ciprofloxacin, a first-line drug recommended by WHO for clinical treatment of intestinal infections. Antimicrobial resistance (AMR) gene analysis indicated that the MDR phenotype of these outbreak strains may be due to the presence of a number of AMR genes, including the blaOXA-1 and blaTEM-1 β-lactamase genes, which are often plasmid-borne and easily transferred. Further virulence gene analysis indicated that these outbreak strains also carried a large number of virulence genes, including 2 types of Salmonella pathogenicity islands (SPI-1 and SPI-2) and many adhesion-related virulence genes. Cluster analysis based on pulse-field gel electrophoresis data and phylogenetic analysis based on WGS revealed that the outbreak clone was closely related to and thus probably derived from local strains. This outbreak caused by multidrug resistant S. Typhimurium highlights the need for government improved strategies for the prevention and control of Salmonella infections.