Antimicrobial susceptibilities, resistance mechanisms and molecular characteristics of toxigenic Clostridioides difficile isolates in a large teaching hospital in Chongqing, China.

OBJECTIVES: Clostridioides difficile ranks among the primary sources of healthcare-related infections and diarrhoea in numerous nations. We evaluated the drug susceptibility and resistance mechanisms of C. difficile isolates from a hospital in Chongqing, China, and identified resistance rates and resistance mechanisms that differed from previous findings. METHODS: The toxin genes and drug resistance genes of clinical strains were detected using Polymerase Chain Reaction (PCR), and these strains were subjected to Multilocus Sequence Typing (MLST). The agar dilution technique was employed for assessing susceptibility of antibiotics. Clinical data collection was completed through a review of electronic medical records. RESULTS: A total of 67 strains of toxin-producing C. difficile were detected. All C. difficile isolates demonstrated susceptibility to both metronidazole and vancomycin. However, resistance was observed in 8.95%, 16.42%, 56.72%, 56.72%, 31.34% and 5.97% of the isolates for tigecycline, tetracycline, clindamycin, erythromycin, moxifloxacin and rifampin, respectively. Among the strains with toxin genotypes A + B + CDT - and belonging to the ST3, six strains exhibited reduced susceptibility to tigecycline (MIC=0.5mg/L) and tetracycline (MIC=8mg/L). The tetA(P) and tetB(P) genes were present in these six strains, but were absent in tetracycline-resistant strains. Resistance genes (ermB, tetM, tetA(P) and tetB(P)) and mutations (in gyrA, gyrB, and rpoB) were identified in resistant strains. CONCLUSIONS: In contrast to prior studies, we found higher proportions of ST3 isolates with decreased tigecycline sensitivity, sharing similar resistance patterns and resistance genes. In the resistance process of tigecycline and tetracycline, the tetA(P) and tetB(P) genes may play a weak role.

Molecular epidemiology and resistance mechanisms of tigecycline-non-susceptible Acinetobacter baumannii isolated from a tertiary care hospital in Chongqing, China.

We studied 34 isolates of Tigecycline-Non-Susceptible A. baumannii (TNAB) obtained from clinical specimens at a large tertiary care hospital in Chongqing, China. These 34 strains belonged to 8 different clones including ST195 (35.3%) and ST208 (17.7%). EBURST analysis found that these 8 ST types belonged to the Clonal Complex 92. Tigecycline resistance-associated genes adeR, adeS, adeL, adeN, rrf, rpsJ, and trm were detected in most strains. The expression level of the resistance-nodulation-cell division (RND) efflux pumps in TNAB strains was higher than the reference strain ATCC19606. 58.8% of strains had a decrease in the tigecycline minimum inhibitory concentration (MIC) after the addition of carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The TNAB strains in our hospital have a high degree of affinity and antibiotic resistance. Regular surveillance should be conducted to prevent outbreaks of TNAB epidemics.

Emergence of Tigecycline and Carbapenem-Resistant Citrobacter freundii Co-Carrying tmexCD1-toprJ1, blaKPC-2, and blaNDM-1 from a Sepsis Patient.

Purpose: This research aims to profile ten novel strains of carbapenem-resistant Enterobacteriaceae (CRE) co-carrying blaKPC and blaNDM. Methods: Clinical CRE strains, along with corresponding medical records, were gathered. To ascertain the susceptibility of the strains to antibiotics, antimicrobial susceptibility tests were conducted. To validate the transferability and cost of fitness of plasmids, conjugation experiments and growth curves were employed. For determining the similarity between different strains, ERIC-PCR was utilised. Meanwhile, whole genome sequencing (WGS) was performed to characterise the features of plasmids and their evolutionary characteristics. Results: During the course of this research, ten clinical CRE strains co-carrying blaKPC and blaNDM were gathered. It was discovered that five out of these ten strains exhibited resistance to tigecycline. A closer examination of the mechanisms underlying tigecycline resistance revealed that tmexCD1-toprJ1, blaKPC-2, and blaNDM-1 existed concurrently within a single Citrobacter freundii strain (CF10). This strain, with a minimum inhibitory concentration (MIC) of 32 mg/L to tigecycline, was obtained from a sepsis patient. Furthermore, an investigation of genome evolution implied that CF10 belonged to a novel ST type 696, which lacked analogous strains. Aligning plasmids exposed that similar plasmids all had less than 70% coverage when compared to pCF10-tmexCD1, pCF10-KPC, and pCF10-NDM. It was also found that tmexCD1-toprJ1, blaKPC-2, and blaNDM-1 were transferred by Tn5393, IS5, and Tn6296, respectively. Conclusion: This research presents the first report of coexistence of tmexCD1-toprJ1, blaKPC-2, and blaNDM-1 in a carbapenem and tigecycline-resistant C. freundii strain, CF10. Importance: Tigecycline is considered a "last resort" antibiotic for treating CRE infections. The ongoing evolution of resistance mechanisms to both carbapenem and tigecycline presents an alarming situation. Moreover, the repeated reporting of both these resistance mechanisms within a single strain poses a significant risk to public health. The research revealed that the genes tmexCD1-toprJ1, blaKPC-2, and blaNDM-1, which cause carbapenem and tigecycline-resistance in the same strain, were located on mobile elements, suggesting a potential for horizontal transmission to other Gram-negative bacteria. The emergence of such a multi-resistant strain within hospitals should raise significant concern due to the scarcity of effective antimicrobial treatments for these "superbugs".

Coexistence of Multidrug Resistance and Virulence in a Single Conjugative Plasmid from a Hypervirulent Klebsiella pneumoniae Isolate of Sequence Type 25.

Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) has received considerable attention. Typically, the genetic elements that confer virulence are harbored by nonconjugative plasmids. In this study, we report a CR-hvKP strain, CY814036, of high-risk sequence type 25 (ST25) and the K2 serotype, which is uncommon among K. pneumoniae isolates but caused serious lung infection in a tertiary teaching hospital in China. Whole-genome sequencing (WGS) revealed a rare conjugative plasmid, pCY814036-iucA, carrying a virulence-associated iuc operon (iucABCD-iutA) coding for aerobactin and determinants of multidrug resistance (MDR), coexisting with a conjugative blaKPC-2-bearing plasmid, pCY814036-KPC2, in the same strain. A conjugation assay showed that pCY814036-iucA and pCY814036-KPC2 could be efficiently cotransmitted from CY814036 to Escherichia coli EC600. Further phenotypic investigation, including antimicrobial susceptibility tests, serum resistance assays, and mouse infection models, confirmed that pCY814036-iucA was capable of cotransferring multidrug resistance and hypervirulence features to the recipient. pCY814036-KPC2 also conferred resistance to antibiotics, including ß-lactams and aminoglycosides. Overall, the rare coexistence of a conjugative MDR-virulence plasmid and a blaKPC-2-bearing plasmid in a K. pneumoniae isolate offers a possible mechanism for the formation of CR-hvKP strains and the potential to significantly accelerate the propagation of high-risk phenotypes. IMPORTANCE The increased reporting of carbapenem-resistant hypervirulent K. pneumoniae is considered a worrisome concern to human health care and has restricted the choice of effective antibiotics for clinical treatment. Moreover, virulence plasmids with complete conjugation modules have been identified, which evolved via homologous recombination. Here, we characterize an ST25 CR-hvKP strain, CY814036, harboring both a conjugative MDR-virulence plasmid and a blaKPC-2-bearing plasmid in China. This study highlights that the cotransmission of drug resistance and virulence plasmids increases therapeutic difficulties and worsens clinical prognoses. Also, active surveillance of the conjugative MDR-virulence plasmid is necessary.

Emergence of a Fatal ST11-KL64 Tigecycline-Resistant Hypervirulent Klebsiella pneumoniae Clone Cocarrying blaNDM and blaKPC in Plasmids.

The combination of hypervirulent Klebsiella pneumoniae (hvKP) infection with carbapenem and tigecycline resistance leads to significant challenges to clinical treatment, with limited available antibiotics and poor patient prognoses. The hvKP12 isolate was obtained from a blood sample of a 74-year-old female in a Chinese teaching hospital. Whole-genome sequencing and microbial characterization were performed to understand the evolutionary mechanism of its resistance. The patient infected with hvKP12 died due to pyemia after a 17-day tigecycline treatment. The antimicrobial susceptibility test identified that hvKP12 was resistant to tigecycline and carbapenems. Variants of tet(A) and the overexpression of efflux pumps related to tigecycline resistance were detected in hvKP12. Conjugation experiments with blaNDM and blaKPC plasmids failed in the laboratory environment. Additionally, phylogenetic analysis suggested that hvKP12 was a clinical high-risk clone of ST11-KL64. We found that the blaKPC-2 gene segment was formed by IS26-mediated gene cluster translocation. Interestingly, the evolutionary pathway of hvKP12 suggested that the KPC-2-producing carbapenem-resistant K. pneumoniae (KPC-2-CRKP) strain evolved into a KPC-NDM-CRKP strain by acquiring the NDM plasmid. To our knowledge, this is the first report of tigecycline-resistant ST11-KL64 carbapenem-resistant hvKP (CR-hvKP) bacteria coproducing blaKPC and blaNDM, causing a fatal blood infection. IMPORTANCE Infections with CRKP coproducing KPC and NDM currently have limited clinical antibacterial options, and tigecycline is used as the last line of defense for therapy. However, this study found that CR-hvKP infection with tigecycline resistance, which may lead to many bacteria being resistant to most commonly used antibiotics, brought significant challenges to clinical treatment. The clonal propagation of ST11-KL64 CRKP should receive sufficient attention.

Analysis of Human Information Recognition Model in Sports Based on Radial Basis Fuzzy Neural Network.

In sports, because the movement of the human body is composed of the movements of the human limbs, and the complex and changeable movements of the human limbs lead to various and complicated movement modes of the entire human body, it is not easy to accurately track the human body movement. The recognition of human characteristic behavior belongs to a higher level computer vision topic, which is used to understand and describe the characteristic behavior of people, and there are also many research difficulties. Because the radial basis fuzzy neural network has the characteristics of parallel processing, nonlinearity, fault tolerance, self-adaptation, and self-learning, it has the advantage of high recognition efficiency when it is applied to the recognition of intersecting features and incomplete features. Therefore, this paper applies it to the analysis of the human body information recognition model in sports. The research results show that the human body information recognition model proposed in this paper has a high recognition accuracy and can detect the movement state of people in sports in real time and accurately.

Analysis of Stadium Operation Risk Warning Model Based on Deep Confidence Neural Network Algorithm.

In this paper, a deep confidence neural network algorithm is used to design and deeply analyze the risk warning model for stadium operation. Many factors, such as video shooting angle, background brightness, diversity of features, and the relationship between human behaviors, make feature attribute-based behavior detection a focus of researchers' attention. To address these factors, researchers have proposed a method to extract human behavior skeleton and optical flow feature information from videos. The key of the deep confidence neural network-based recognition method is the extraction of the human skeleton, which extracts the skeleton sequence of human behavior from a surveillance video, where each frame of the skeleton contains 18 joints of the human skeleton and the confidence value estimated for each frame of the skeleton, and builds a deep confidence neural network model to classify the dangerous behavior based on the obtained skeleton feature information combined with the time vector in the skeleton sequence and determine the danger level of the behavior by setting the corresponding threshold value. The deep confidence neural network uses different feature information compared with the spatiotemporal graph convolutional network. The deep confidence neural network establishes the deep confidence neural network model based on the human optical flow information, combined with the temporal relational inference of video frames. The key of the temporal relationship network-based recognition method is to extract some frames from the video in an orderly or random way into the temporal relationship network. In this paper, we use several methods for comparison experiments, and the results show that the recognition method based on skeleton and optical flow features is significantly better than the algorithm of manual feature extraction.