Background: The occurrence and dissemination of hypermucoviscous and hypervirulent Klebsiella pneumoniae (hm-hvKp) isolates in clinical settings are a critical public health problem in the world. However, the data on these isolates in community populations are limited. This study aims to understand the prevalence and molecular characteristics of hm-hvKp isolates in community patients in Shanghai, China. Methods: In 2018, an active surveillance system focused on hm-hvKp in community diarrhoeal cases was implemented in Pudong New Area, Shanghai, China, involving 12 sentinel hospitals. The antimicrobial susceptibility of hm-hvKp isolates from fecal samples was tested, and whole-genome sequencing (WGS) was performed to predict the serotypes and sequence types and to identify antimicrobial resistance determinants, virulence determinants, and phylogenetic clusters. Results: The overall prevalence of hm K. pneumoniae isolates was 2.48% (31/1252), with the proportions of 1.76% (22/1252) for hm-hvKp and 0.72% (9/1252) for hm not hv K. pneumoniae. The prevalence of hm-hvKp isolates among different age groups and different months was statistically significant. All the 22 hm-hvKp isolates were susceptible to 20 antimicrobial agents and only carried bla_SHV gene, and KL1 and KL2 accounted for eight (36.36%) cases and seven (31.82%) cases, respectively. The eight ST23/KL1 isolates belonged to the predominant CG23-I clade, which typically possessed the virulence determinants profile of rmpA/rmpA2-iro-iuc-ybt-irp-clb. The five ST86/KL2 isolates were assigned to the global clusters ST86/KL2-1 (n=2), ST86/KL2-2 (n=2), ST86/KL2-3 (n=1), all lack of the clb gene. Shanghai ST23/KL1 and ST86/KL2 isolates were closely related to the global isolates from liver abscesses, blood, and urine. Conclusion: Hm-hvKp is carried by the community population of Shanghai, with ST23/KL1 and ST86/KL2 isolates predominant. Hm-hvKp isolates of different continents, different sources, and different virulence levels were closely related. Ongoing surveillance of hm-hvKp isolates in the community population is warranted.

Background: Shigella spp. are critical pathogens causing diarrheal diseases. This study analyzed the epidemiological characteristics, antimicrobial resistance profiles, virulence factor profiles, and molecular patterns of Shigella isolates in Pudong New Area, Shanghai, from 2013 to 2024. Materials and Methods: Antimicrobial susceptibility of Shigella isolates was determined using the broth microdilution method. All molecular characterization analyses were based on whole-genome next-generation sequencing of Shigella strains. Results: A total of 55 Shigella spp. isolates were obtained from 17,670 enrolled diarrheal cases between 2013 and 2024, including 47 S. sonnei and 8 S. flexneri isolates. Resistance rates to sulfamethoxazole-trimethoprim (SXT), streptomycin (STR), nalidixic acid (NAL), ampicillin (AMP), and tetracycline (TET) all exceeded 90.00%. The resistance rate to azithromycin (AZI) increased from 12.50% to 60.00% with a fluctuating upward trend from 2013 to 2019; 97.87% of S. sonnei and 100.00% of S. flexneri isolates were multidrug-resistant. These isolates harbored multiple resistance genes and virulence factors. S. sonnei was dominated by ST152, while S. flexneri was predominantly ST245. These isolates were phylogenetically close to domestic (Beijing) and international (USA) strains of the same sequence typing collected at different time points, suggesting a common origin and stable transmission characteristics. Conclusion: From 2013 to 2024, the prevalent Shigella species in Pudong were S. sonnei and S. flexneri. Shigella isolates exhibited high resistance rates, and the situation of multidrug resistance was severe. Therefore, strengthening antimicrobial resistance monitoring and controlling regional transmission are of great significance. Meanwhile, genomic surveillance of Shigella ST152/ST245 is recommended for Pudong’s enteric pathogen control programs.

Objective: To analyze the phenotypic and genomic characteristics of a non-typhoidal Salmonella bile isolate from a patient with chronic diarrhoea secondary to acute cholecystitis. Methods: The patient presented with chronic diarrhoea lasting for two weeks, which was secondary to acute cholecystitis. The non-typhoidal Salmonella bile isolate was identified using biochemical tests, mass spectrometry, serum agglutination tests, and antimicrobial susceptibility testing. Subsequently, whole-genome sequencing (WGS) was performed to predict and annotate the serotype, multilocus sequence typing (MLST), antimicrobial resistance genes (AMR), mobile genetic elements (MGEs), and virulence genes of the isolate. Results: The isolate was identified as Salmonella spp. by biochemical tests and mass spectrometry. The serotype of the isolate identified by serum agglutination tests was consistent with WGS prediction and was identified as Salmonella Stanley (1,4,5,12: d:1,2, ST29). It was resistant to six antimicrobial agents, including ampicillin, ciprofloxacin, cefotaxime, azithromycin, trimethoprim/sulfamethoxazole, and chloramphenicol. Five major classes of antimicrobial agents, comprising a total of 14 resistance genes were screened, including β-lactam resistance genes: bla_TEM-1B, bla_OXA-1, and bla_DHA-1; quinolone resistance gene: qnrB4 and aac(6′)-Ib-cr; macrolide resistance genes: mph(A), mph(E), and msr(E), and folate pathway inhibitor resistance genes: sul1, sul2, and dfrA14; chloramphenicol resistance genes: floR, catA2 and catB3. T57S mutation in the parC gene was detected in the quinolone resistance-determining region (QRDR). Three plasmid replicons (IncHI2/IncHI2A, IncR, IncN) and three insertion MGEs were predicted. Forty-two virulence genes were predicted, of which 25 were secretion and transporter genes, and ten were fimbrial adherence genes. Only one invasive protein-regulated gene(inv) was found in Salmonella Pathogenicity Islands 1(SPI-1), and no Typhoid toxin genes were predicted. Conclusion: The case of Salmonella Stanley ST29 isolated from a patient with diarrhoea lasting 55 days secondary to cholecystitis aligns with the characteristics of high drug resistance and relatively low virulence. This highlights the need for increased vigilance in clinical practice regarding invasive cases and the significant disease burden associated with the intestinal migration of antimicrobial-resistant Salmonella isolates.