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BACKGROUND: Klebsiella pneumoniae (Kp) is a common community-acquired and nosocomial pathogen. Carbapenem-resistant and hypervirulent (CR-hvKp) variants can emerge rapidly within healthcare facilities and impacted by other infectious agents such as COVID-19 virus. METHODS: To understand the impact of COVID-19 virus on the prevalence of CR-hvKp, we accessed Kp genomes with corresponding metadata from GenBank. Sequence types (STs), antimicrobial resistance genes, and virulence genes, and those scores and CR-hvKp were identified. We analyzed population diversity and phylogenetic characteristics of five most common STs, measured the prevalence of CR-hvKp, identified CR-hvKp subtypes, and determined associations between carbapenem resistance gene subtypes with STs and plasmid types. These variables were compared pre- and during the COVID-19 pandemic. FINDINGS: The proportion of CR-hvKp isolates increased within multiple STs in different continents during the COVID-19 pandemic and persistent CR-hvKp subtypes were found in common STs. blaKPC was dominant in CG258, blaKPC-2 was detected in 97 % of the ST11 CR-hvKp, blaNDM subtypes were prominent in ST147 (87.4 %) and ST307 (70.8 %); blaOXA-48 and its subtypes were prevalent in ST15 (80.5 %). The possession of carbapenemase genes was different among subclades from different origins in different periods of time within each ST. IncFIB/IncHI1B hybrid plasmids contained virulence genes and carbapenemase genes and were predominant in ST147 (67.37 %) and ST307 (56.25 %). INTERPRETATION: The prevalence of CR-hvKp increased during the COVID-19 pandemic, which was evident by an increase in local endemic clones. This process was facilitated by the convergence of plasmids containing carbapenemase genes and virulence genes. These findings have implications for the appropriate use of antimicrobials and infection prevention and control during outbreaks of respiratory viruses and pandemic management.

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Blood stream infection (BSI),a blood-borne disease caused by microorganisms such as bacteria,fungi,and viruses,can lead to bacteremia,sepsis,and infectious shock,posing a serious threat to human life and health.Identifying the pathogen is central to the precise treatment of BSI.Traditional blood culture is the gold standard for pathogen identification,while it has limitations in clinical practice due to the long time consumption,production of false negative results,etc.Nanopore sequencing,as a new generation of sequencing technology,can rapidly detect pathogens,drug resistance genes,and virulence genes for the optimization of clinical treatment.This paper reviews the current status of nanopore sequencing technology in the diagnosis of BSI.

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Streptococcus pneumoniae is one of the most common bacterial pathogens of a wide range of community-acquired infections. It has been more and more recognized that this bacterium could also play a role as a cause of nosocomial infections. In this study, by retrospective analysis of the phenotypic resistance characteristics and genomic characteristics of 52 S. pneumoniae isolates in a hospital in Beijing, China, from 2018 to 2022, we explored the carriage of resistance genes and mutations in penicillin-binding proteins corresponding to the resistances, and identified the population diversity based on the prediction of serotypes and identification of sequence types (STs). The isolates displayed resistances to erythromycin (98%), tetracycline (96%), sulfonamide (72%) and penicillin G (42%). Among the 52 isolates, 41 displayed multiple-drug resistance. In total, 37 STs and 21 serotypes were identified, and the clonal complex 271 serogroup 19 was the most prevalent subtype. Only 24 isolates (46.2%) of 7 serotypes were covered by the 13-valent pneumococcal conjugate vaccination. The isolates showed high carriages of resistance genes, including tet(M) (100%) and erm(B) (98.1%); additionally, 32 isolates (61.5%) had mutations in penicillin-binding proteins. We also observed 11 healthcare-associated infections and 3 cases infected by different subtypes of isolates. We did not find nosocomial transmissions between the patients, and these cases might be associated with the asymptomatic colonization of S. pneumoniae in the human population. Our results called for further active surveillance of these subtypes, as well as the continuous optimization of the treatment protocols.

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OBJECTIVE: To explore if random forest (RF) model can predict the prognosis of hospital-acquired Klebsiella pneumoniae infection as well as traditional logistic regression(LR) model. METHODS: A total of 254 cases of hospital-acquired Klebsiella pneumoniae infection in a tertiary hospital in Beijing from January 2016 to December 2020 were retrospectively collected. Appropriate influencing factors were selected by referring to relevant articles from the aspects of basic clinical information and contact history before infection, and divided into a training set and a test set. Both the RF and LR models were trained by the training set, and using testing set to compare these two models. RESULTS: The prediction accuracy of the LR model was 87.0%, the true positive rate of the LR model was 94.7%; the false negative rate of the LR model was 5.3%; the false positive rate of the LR model was 35%; the true negative rate of the LR model was 65%; the sensitivity of the LR model for the prognosis prediction of hospital-acquired Klebsiella pneumoniae infection was 94.7%; and the specificity was 65%. The prediction accuracy of the RF model was 89.6%; the true positive rate of the RF model was 92.1%; the false negative rate of the RF model was 7.9%; the false positive rate of the RF model was 21.4%; the true negative rate of the RF model was 78.6%; the sensitivity of the RF model for the prognosis prediction of hospital-acquired Klebsiella pneumoniae infection was 92.1%; and the specificity was 78.6%. ROC curve shows that the area under curve(AUC) of the LR model was 0.91, and that of the RF model was 0.95. CONCLUSION: The RF model has higher specificity, sensitivity, and accuracy for the prognostic prediction of hospital-acquired Klebsiella pneumoniae infection than the LR model and has greater clinical application prospects.

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Multidrug-resistant (MDR) hypervirulent Klebsiella pneumoniae (hvKp) sequence type (ST) 23 (MDR-ST23-hvKp) is emerging in China. Despite its increasing importance, this pathogen has not yet been subject to detailed genomic interrogation. We identified 28 ST23 Kp isolated from three hospitals in China. The organisms were subjected to antimicrobial susceptibility testing and whole-genome sequencing (WGS). These novel genomic sequences were analyzed in combination with 218 publicly available genome sequences. We performed molecular serotyping and subtyping, assessed the composition of virulence-associated and antimicrobial resistance (AMR) genes, and determined mobile elements associated with horizontal gene transfer. Two MDR-ST23-hvKp were sequenced by long-read sequencing. The genetic characteristics of MDR and non-MDR isolates were compared. Among the 28 novel ST23 isolates, all were hvKp and 2/28 (7.1%) were MDR-hvKp. From the collection of 246 genomes, KL1 was the predominant serotype (224/246; 91.1%) and the siderophore combination of YbST46-CbST29-AbST1-SmST2 was dominant (101/246; 41.1%); 34/246 (13.8%) organisms belonged to MDR-ST23-hvKp. IncF and IncR plasmid replicons were significantly more prevalent in the MDR group (P < 0.05) than in the non-MDR group. IS26 was commonly involved in AMR acquisition. We observed that the acquisition of AMR genes within the ST23-hvKp was not associated with a loss of virulence genes. A 28-bp fusion site was highly conserved with two copies of the virulence-associated plasmid in ST23-hvKp, and we harbored by some of the IncFII plasmids of MDR-ST23-hvKp. Our data suggest that MDR-ST23-hvKp has undergone multiple independent genetic acquisition and recombination events within different sublineages. Notably, the acquisition of IncFII plasmids and/or IS26 contributed to the horizontal transfer of AMR genes within ST23-hvKp. Genomic surveillance is essential for further tracking of kMDR-ST23-hvKp. IMPORTANCE Hypervirulent Klebsiella pneumoniae (hvKp) has become the dominant pathotype in hospitals recently. The sequence type (ST) 23 hvKp, which are more commonly associated with the community-acquired infections previously, may have the capacity to acquire multidrug-resistant (MDR) phenotypes creating a new "superbug" (MDR-hvKp) in hospital. In the present study, we studied the associations of MDR and hypervirulence among ST23 K. pneumoniae from our strain collection and publicly accessible genome data. By comparative analysis of the carriage of resistance genes, virulence genes plasmid replicon types, and plasmid sequences, we found that IncFII plasmids were significantly more prevalent in MDR isolates and IS26 were commonly involved in resistance gene acquisition. We also discovered new MDR plasmids. These results provided an overview landscape of the genetic elements associated with MDR-ST23-hvKp based on currently accessible genome data and calling for further genomic surveillance and well-designed control studies of MDR-ST23-hvKp.

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