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Objectives: Although hypervirulent Klebsiella pneumoniae (hvKp) is an increasing public health problem, there remains limited epidemiological information regarding hvKp infections in children. Here, we conducted a clinical, molecular and phenotypic surveillance of hvKp strains in a pediatric population. Methods: Non-repetitive K. pneumoniae (Kp) strains consecutively collected during 2019-2020 were screened for hypervirulence genes (prmpA, prmpA2, iucA, iroB, and peg344) using PCR. Positive strains were further characterized by four phenotypic assays (string test, serum killing assay, siderophore production, Galleria mellonella lethality assay), followed by murine sepsis model to determine virulence in vitro and in vivo. Also, capsular types, sequence types, plasmid replicon types, antimicrobial resistance determinants and susceptibility were analyzed. Results: A total of 352 isolates were collected, wherein 83 (23.6%) were hypervirulence genes-positive Kp (hgKp). A significant increase in KPC-2-producing KL47-ST11 among hgKp strains was observed, from 5.3% (1/19) in 2019 to 67.6% (25/37) in 2020 (P<.0001), suggesting the potential dissemination of the hybrid virulence and carbapenem-resistance encoding plasmid among children. Further, hgKp isolates were classified into hvKp (n = 27) and hgKp-low virulence (hgKp-Lv) (n = 56) based on virulence phenotypic assays. In hvKp, diverse genetic clones were observed and K1-ST23 or K2-ST25 strains with sensitivity to multiple antibiotics were prevalent (25.9%, 7/27). Compared with hgKp-Lv, hvKp infection had a higher propensity to involve severe pneumonia (22.2% vs. 12.5%) in elder children and significant higher mortality in mice (P = 0.0086). Additionally, either hvKp or hgKp-Lv infections were mostly healthcare-associated and hospital-acquired (74.1% vs. 91.9%). Conclusions: These data suggest that K1-ST23 and K2-ST25 are high-risk clones of hvKp, and the genetic convergence of virulence and carbapenemresistance is increasing among children. Control measures are needed to prevent the dissemination in clinical settings. [ABSTRACT FROM AUTHOR]

Platanus acerifolia, London plane tree, a significant source of airborne allergens, is widely grown in Shanghai and other cities in China. In recent decades, little has been known regarding the influence of the allergens on sensitizing the population in the Shanghai area. The aims of this study were to purify and characterize the two major allergens and to confirm the immunological activities of these pollen allergens in Shanghai. Crude extract was purified with a HiTrap SP column and a Sephedex G75 column. Immunodetection was performed with ELISA and immunoblotting. Following gel proteolytic digestion and mass spectrometry, the tandem MS (MS/MS) peptide mass fingerprint was obtained and the MASCOT search engine was used to identify the peptide. The accession number of the interesting homologous data and all the sequence information was acquired by an internet database and the evolutionary trees were drawn with Mega 4.0 software. Two proteins with molecular weights of 43 kDa and 18 kDa were purified from P. acerifolia pollen extract. The purified proteins were identified as pollen allergen Pla a 1 and Pla a 2 via mass spectrometry. The proteins have immunological activities with human IgE antibodies. According to the ELISA results, 12% (5/41) of the subjects were sensitive to Pla a 1 and 9% (4/41) were sensitive to Pla a 2. Pla a 1 and Pla a 2 are thus important allergens for patients with an allergic reaction to P. acerifolia pollen in Shanghai. [ABSTRACT FROM AUTHOR]