Objective To gain insights into the biological characteristics of different populations of Culex tritaeniorhynchus within and around the Yellow Sea wetland from the perspective of the occurrence of resistance, we investigated the levels of resistance to deltamethrin and kdr gene mutation in the wetland and its peripheral areas. Methods Specimens were collected from Cx. tritaeniorhynchus populations at two monitoring sites in the Rare Bird National Nature Reserve and Tiaozi Ni Wetland Scenic Area, and also from two populations in Yancheng City and the Liuhe District of Nanjing, and the resistance of these mosquitoes to deltamethrin was determined using the CDC biotest bottle method. For each concentration of deltamethrin assessed, a random subset of exposed specimens was selected for amplification of the kdr gene fragment, followed by Sanger sequencing to identify and analyze resistance-associated mutations. Results The LC50 levels of deltamethrin among mosquitoes from the four populations in Luhe, Yancheng, the Rare Bird National Nature Reserve and the Tiaozi Ni Wetland Scenic Area were 2.048 5, 7.798 2, 3.473 3, and 17.695 5 mg/mL, respectively, with corresponding concentrations of deltamethrin ranging from 0.005 to 5.000,0.050 to 50.000,0.050 to 25.000 and 0.050 to 50.000 mg/mL, respectively. Furthermore, the ranges of the KT50 values were 11.76-107.43, 67.05-216.30,29.77-107.43 and 28.40-329.51 min; the 1-h knockdown rates were 34.58%-99.15%, 9.52%-43.80%, 55.09%-73.01%, and 10.09%-68.07%; and the 24-h mortality rates were 12.15%-67.52%,9.52%-79.56%,13.17%-82.21%, and 11.01%-78.99%, respectively. With respect to kdr gene mutation, we assayed a total of 63,70,59, and 57 mosquitoes for the four populations, for which we detected L1014F mutation frequencies of 14.29%, 35.00%, 20.34%, and 31.58%, respectively, with a majority of these mutations being heterozygous for resistance. In addition, five adult mosquitoes were identified has having synonymous mutations at site 1011[i. e. , AAT(asparagine)mutation to AAC(asparagine)]. Conclusions Our findings revealed the clear resistance of Cx. tritaeniorhynchus to deltamethrin in the Yancheng region of the Yellow Sea wetland, and the resistance phenotype and kdr frequency of Cx. tritaeniorhynchus in the wetland environment were comparable to those of Cx. tritaeniorhynchus in the wetland environment, thereby indicating that the resistance of different populations of Cx. tritaeniorhynchus was homogeneous under the pressure of different insecticide selection within and around the wetland. However, the underlying mechanisms need to be further studied.

Background: Malignant pleural effusion (MPE), a common complication of advanced cancers, is associated with poor prognosis and reduced quality of life. Although host–tumor interactions are known to drive MPE development, the associated immune dynamics during disease progression remain unclear. Using a Lewis lung carcinoma-induced MPE model in C57BL/6JNidfc mice, we systematically evaluated general parameters and immune cell changes at two-day intervals throughout disease progression. Results: The day of Lewis lung carcinoma cell injection into the pleural space was designated as day 0. By day 10 post-injection (p.i.), MPE-bearing mice exhibited ~ 10% body weight loss, marking the experimental endpoint. Pleural tumor mass and pleural effusion volume were minimal up to day 4 p.i. but increased sharply from day 6 onward.CD45⁺ immune cell counts rose over time, and days 6, 8, and 10 p.i. marked key stages of MPE progression. On day 6, B cells, T cells, and natural killer cells, but not macrophages and neutrophils, increased significantly compared to earlier timepoints. By day 8, all immune cell subsets except T cells exceeded day 6 levels, and at day 10, natural killer cell numbers declined while others continued to increase. Besides, the numbers of CD8⁺ T cells, Th1 cells, regulatory T cells, and M2 macrophages progressively increased from day 6 to 10. Based on these data, days 6 and 10 were defined as early and advanced MPE stages, respectively, with distinct immune phenotypes. In advanced MPE, CD8⁺ T cells displayed reduced IFN-γ, TNF-α, Granzyme B, Perforin, FasL, and Ki-67, but upregulated PD-1 and CTLA-4 relative to early stage. Similarly, Th1 cells showed decreased IFN-γ, TNF-α, and IL-2 production along with reduced Ki-67 expression. Advanced-stage M2 macrophages exhibited lower MHC-II levels and impaired phagocytosis, but higher PD-L1 and IL-10 production, while neutrophils showed reduced TNF-α release and phagocytic activity. Conclusions Our findings characterize the temporal immune dynamics associated with MPE progression in a mouse model, revealing a transition from an early immunostimulatory state to a late immunosuppressive state. This study enhances our understanding of MPE immunopathogenesis and provides a foundation for developing precise, stagespecific therapeutic strategies.

ObjectiveTo establish the mouse models of psoriasis-like lesions induced by continuous cold exposure or intermittent cold exposure combined with imiquimod （IMQ）， and to evaluate the interventional effects of Kaixuan Jiedu core prescription （KXJD） on the two models. MethodsMale C57BL/6J mice were selected and classified into two experimental batches. The first batch of 36 mice was randomized into a room temperature group， a continuous cold exposure （10 ℃/24 h） group， and an intermittent cold exposure （10 ℃/6 h） group. Each group was further divided into a normal subgroup and a model subgroup （topical application of IMQ to induce skin lesions）， with 6 mice in each subgroup， for modeling and evaluation. The second batch of 54 mice， with 6 in each group， were subjected to the same temperature grouping with an additional KXJD （30.42 g·kg^-1， continuous gavage for 5 days） group. Comprehensive evaluation of model characteristics and KXJD efficacy was conducted through Psoriasis Area and Severity Index （PASI） scoring， skin temperature measurement by infrared thermography， histopathological observation by hematoxylin-eosin （HE） staining， detection of vascular endothelial growth factor （VEGF） and platelet endothelial cell adhesion molecule 1 （CD31） by immunohistochemistry， detection of Claudin-1 and Occludin by immunofluorescence assay， determination of serum levels of tumor necrosis factor-α （TNF-α） and interleukin （IL）-10 by enzyme-linked immunosorbent assay （ELISA）， and quantification of mRNA levels of IL-17A， IL-23， IL-6， and chemokine ligand 20 （CCL20） in skin lesions by quantitative Real-time polymerase chain reaction （Real-time PCR）. ResultsModel mice in all temperature groups exhibited typical psoriasis-like skin lesions. Compared with the normal groups， the model groups showed increased PASI scores， decreased skin temperatures （P<0.05）， obvious epidermal thickening， parakeratosis， and dermal inflammatory cell infiltration， as well as elevated mRNA levels of IL-17A， IL-23， IL-6， and CCL20 （P<0.05）. Cold exposure further aggravated psoriasis. The total PASI score of the intermittent cold exposure model group was higher than that of the room temperature model group （P<0.05）. The serum IL-10 did not show a compensatory elevation， and the blood vessels presented a characteristic of elevated CD31 expression （P<0.05） without a synchronous increase in VEGF. The continuous cold exposure model group exhibited more significant dermal capillary tortuosity and dilation， with the highest mRNA levels of IL-17A， IL-23， IL-6， and CCL20 among all groups. Compared with the respective model groups， KXJD intervention alleviated skin lesions， reduced epidermal thickness and inflammatory cell infiltration， and increased skin temperature， with the temperature increase being particularly significant in the intermittent cold exposure+KXJD group （P<0.05）. Furthermore， KXJD down-regulated the expression of VEGF and CD31， restored the expression of Claudin-1 and Occludin， decreased the mRNA levels of IL-17A and IL-23 （P<0.05）， and reduced the serum TNF-α level. ConclusionThis study successfully established compound psoriasis-like mouse models induced by cold exposure combined with IMQ. It confirms that cold aggravates the severity of psoriasis by exacerbating the closure of Xuanfu （sweat pores）， microcirculation disorders， and immune imbalance. Moreover， different cold exposure patterns have distinct mechanism differences. Continuous cold exposure focuses on enhancing the inflammatory response via the IL-23/IL-17 axis and angiogenesis， simulating chronic aggravation under a long-term cold environment. Intermittent cold exposure tends to impair immune regulation and induce microvascular endothelial stress， corresponding to acute exacerbations caused by sudden temperature drops. KXJD can effectively alleviate psoriasis-like skin lesions under cold conditions by unblocking Xuanfu， regulating vasomotor function， and correcting abnormal immune-inflammatory responses.

ObjectiveTo investigate the ameliorative effects of Kaixuan Jiedu core prescription （KXJD） on skin lesions in psoriasis-like mouse models under cold environment exposure， and to analyze its influences on transient receptor potential （TRP） channels and related neuroimmune regulatory factors. MethodsThirty-six C57BL/6J mice were randomized into 6 groups， with 6 mice in each group. Two feeding conditions were set： Normal temperature and cold ［simulating a cold environment at （10±0.5） ℃， for 6 h daily］. Mice were induced to develop psoriasis-like lesions by applying imiquimod externally. The model mice were allocated into model groups and KXJD （30.42 g·kg^-1， continuous gavage for 5 days） groups. Normal mice were used as the control group. Specifically， mice were allocated into normal temperature， normal temperature model， normal temperature+KXJD， cold exposure control， cold exposure model， and cold exposure+KXJD groups. The pathological changes in skin lesions were observed by hematoxylin-eosin （HE） staining. The expression of cluster of differentiation （CD） 3⁺ T lymphocytes， CD11c⁺ dendritic cells （DCs）， phosphorylated extracellular signal-regulated kinase （p-ERK）， and substance P （SP） were detected by immunofluorescence assay. The protein level of transient receptor potential cation channel subfamily M member 8 （TRPM8） in the skin tissue was determined by Western blot. The expression of TRPM8， transient receptor potential cation channel subfamily V member 1 （TRPV1）， transient receptor potential cation channel subfamily A member 1 （TRPA1）， and transient receptor potential cation channel subfamily V member 2 （TRPV2） at the protein and mRNA levels was determined by immunohistochemistry and Real-time PCR， respectively. The levels of calcitonin gene-related peptide （CGRP） and neuropeptide Y （NPY） in the serum were analyzed by enzyme-linked immunosorbent assay （ELISA）. The enrichment analysis of differentially expressed genes （DEGs） and TRP pathway network construction were conducted based on the GEO database. The co-expression of TRPM8 and CGRP in the skin lesions was verified by immunofluorescence double labeling. ResultsBoth the normal temperature and cold exposure model groups showed typical psoriasis-like skin lesions. Compared with the normal temperature and cold exposure control groups， the model groups had excessive epidermal keratinization， thickened spinous layer， and inflammatory infiltration in the dermis， with increased pathological scores （P<0.05）， increased infiltration of CD3⁺ and CD11c⁺ cells and expression of p-ERK and SP， upregulated mRNA levels of TRPM8， TRPA1， and TRPV2， downregulated mRNA level of TRPV1 （P<0.05）， and reduced content of CGRP and increased content of NPY in the serum. Compared with the normal temperature and cold exposure model groups， KXJD reduced the pathological manifestations and pathological scores of psoriasis-like skin lesions （P<0.05）， and inhibited the infiltration of CD3⁺ and CD11c⁺ cells and the expression of p-ERK and SP. Gene enrichment analysis suggested that the DEGs of psoriasis were significantly enriched in the interleukin （IL）-17 signaling pathway and TRP channel inflammatory regulation. Compared with the normal temperature and cold exposure model groups， KXJD reversed the abnormal mRNA levels of genes related to the TRP channel subfamilies （P<0.05）， increased the CGRP level， and decreased the NPY level. Immunofluorescence double labeling further confirmed that compared with the model groups， KXJD down-regulated the co-expression of TRPM8 and CGRP in the skin lesions. ConclusionKXJD may ameliorate psoriasis-like skin lesions by downregulating the overexpressed cold-sensitive receptor TRPM8 in skin lesions and correcting the disorder of neuropeptide （such as SP and CGRP） release mediated by it， thereby inhibiting the IL-23/helper T cell 17 （Th17） core inflammatory pathway， suppressing the infiltration of inflammatory cells and the activation of the ERK signaling pathway， and regulating the Xuanfu （sweat pore）-TRPM8-neuroimmune response axis.

ObjectiveTo investigate the ameliorative effects and mechanisms of Kaixuan Jiedu core prescription （KXJD） on neuroimmunological inflammation in imiquimod （IMQ）-induced psoriasis-like mice. MethodsA total of 24 C57BL/6J mice were randomly divided into four groups （n=6）： Normal， model， KXJD， and tropomyosin receptor kinase A （TrkA） inhibitor GW441756 groups. The mice in the model， KXJD， and GW441756 groups were topically treated with 5% IMQ cream （62.5 mg·d^-1） on the back to induce psoriasis-like inflammation. The KXJD group received KXJD by gavage （30.42 g·kg^-1）， the GW441756 group received intraperitoneal injection of GW441756 （10 mg·kg^-1）， and the normal and model groups received an equal volume of normal saline by gavage， with continuous intervention for 5 days. The severity of skin lesions was evaluated using the psoriasis area and severity index （PASI）. Hematoxylin-eosin （HE） staining was used to measure epidermal thickness and observe pathological changes in the lesioned skin. Immunohistochemistry was employed to detect the expression of proliferating cell nuclear antigen （Ki67） and interleukin-17A （IL-17A） in the lesioned skin. Enzyme-linked immunosorbent assay （ELISA） was used to quantify the levels of interleukin-23 （IL-23） and calcitonin gene-related peptide （CGRP） in the lesioned tissues. Western blot was used to detect the expression of TrkA and phosphorylated TrkA （p-TrkA）. Immunofluorescence assay was performed to detect the expression of TrkA receptor， protein gene product 9.5 （PGP9.5）， cluster of differentiation 11c （CD11c）， and CGRP in the lesions. Flow cytometry was used to detect the activation of splenic dendritic cells （DCs）. ResultsCompared with the normal group， the model group exhibited typical psoriasis-like inflammation， characterized by erythema， infiltration and scaling， with histopathological findings of epidermal hyperkeratosis and acanthosis. The model group showed significantly increased expression of Ki67， IL-17A， IL-23 and p-TrkA （P<0.05， P<0.01）， increased fluorescence intensity of CD11c， and significantly decreased CGRP expression （P<0.05）. The splenic DC activation was significantly enhanced， as indicated by the increased mean fluorescence intensity （MFI） of CD86 （P<0.05）. Compared with the model group， both the KXJD and GW441756 groups showed amelioration of the psoriasis-like skin inflammation， with significantly down-regulated expression of IL-17A， IL-23 and p-TrkA （P<0.05， P<0.01）， significantly up-regulated expression of CGRP （P<0.01）， reduced CD11c⁺ DC infiltration， and restored splenic DC activation balance （down-regulated CD86 MFI and up-regulated CD80 and CD40 MFI）. Furthermore， the inhibitory effect of KXJD on Ki67 was significantly superior to that of the GW441756 group （P<0.01）. ConclusionKXJD may alleviate IMQ-induced psoriasis-like inflammation in mice by targeting and inhibiting TrkA receptor phosphorylation， regulating CGRP expression in the lesions， and ameliorating aberrant activation of dendritic cells， while also significantly inhibiting keratinocyte proliferation.

ObjectiveTo investigate the effects and molecular mechanisms of Kaixuan Jiedu core prescription （KXJD） on neuroinflammation and immuno-inflammation in the mouse model of imiquimod （IMQ）-induced psoriasis-like skin lesions by regulating the nerve growth factor （NGF）-tropomyosin receptor kinase A （TrkA）/transient receptor potential vanilloid 1 （TRPV1）-protease-activated receptor-2 （PAR-2） signaling pathway. MethodsA psoriasis-like skin lesion model was established in male C57BL/6J mice with IMQ. A total of 24 mice were randomized into four groups （n=6 per group）： Blank control， model， methotrexate （MTX， 1 mg·kg^-1）， and KXJD （30.42 g·kg^-1）. Immunohistochemistry was employed to detect the expression of cluster of differentiation 3 （CD3）， EGF-like module-containing mucin-like hormone receptor-like 1 （F4/80）， lymphocyte antigen 6 complex locus G （Ly-6G）， substance P （SP）， calcitonin gene-related peptide （CGRP）， NGF， phosphorylated TrkA （p-TrkA）， phosphorylated TRPV1 （p-TRPV1）， and PAR-2 in skin lesions. Serum levels of interleukin-17A （IL-17A） and interleukin-23 （IL-23） were measured by enzyme-linked immunosorbent assay （ELISA）. Immunofluorescence assay and Western blot were employed to determine the expression of phosphorylated p38 mitogen-activated protein kinase （p-p38 MAPK） and phosphorylated nuclear factor-κB p65 （p-NF-κB p65）. Reverse transcription quantitative polymerase chain reaction （Real-time PCR） was used to measure the mRNA levels of interleukin-1β （IL-1β）， tumor necrosis factor （TNF）， interleukin-6 （IL-6）， and C-X-C motif chemokine ligand 1 （CXCL1） in skin lesions. Correlation analysis was performed. ResultsCompared with the blank control group， the model group showed increased positive areas of CD3⁺， F4/80⁺， and Ly-6G⁺ in skin lesions （P<0.05）， elevated serum levels of IL-17A and IL-23 （P<0.05）， increased positive areas of SP and CGRP in skin lesions （P<0.05）， increased positive areas of NGF， p-TrkA， p-TRPV1， and PAR-2 （P<0.05）， elevated ratios of p-p38 MAPK/p38 MAPK and p-NF-κB p65/NF-κB p65 （P<0.05）， and upregulated mRNA levels of IL-1β， TNF， IL-6， and CXCL1 （P<0.05）. Compared with those in the model group， all the above indicators were reversed in the KXJD group （P<0.05）. MTX only downregulated the expression of p-TRPV1 and PAR-2 （P<0.05）， with no significant effects on the expression of NGF， p-TrkA， or CGRP. ConclusionKXJD inhibits the NGF-TrkA/TRPV1-PAR-2 signaling pathway to reduce neuropeptide release and simultaneously downregulates the p38 MAPK/NF-κB signaling pathway and the expression of downstream pro-inflammatory factors to ameliorate psoriasis-like neuroinflammation and immuno-inflammation. The therapeutic effect of KXJD on psoriasis-like inflammation is closely associated with the inhibition of the NGF-TrkA/TRPV1-PAR-2 signaling pathway. This study provides experimental evidence for the modern interpretation of the Xuanfu theory.

Objective: To analyze the epidemiological characteristics of hand, foot and mouth disease (HFMD) among children aged 0-9 years in Guangzhou, so as to provide reference basis for further exploring scientifically effective prevention and control measures. Methods: Reported cases of HFMD in children aged 0-9 years in Guangzhou City from 2013-2025 were selected from China disease prevention and control information system, and the incidence in different years was analyzed descriptively; the trends of the composition ratio and incidence in various age groups were analyzed by using the Joinpoint regression model, spatial autocorrelation analyses were performed at the district level, and the seasonal autoregressive integrated moving average model (SARIMA) was applied to predict annual incidence rate for 2026. Results: From 2013 to 2025, the average annual reported incidence rate of HFMD among children aged 0-9 years in Guangzhou was 2 513.98/100 000, showing a fluctuating trend. Peaks of incidence occurred from May to July and from September to October. The male to female ratio was 1.49∶1. The average annual incidence rate was 4 743.99/100 000 in the 0-1 years age group, 3 298.19/100 000 in the 2-5 years age group, and 544.22/ 100 000 in the 6-9 years age group. Joinpoint regression analysis showed a decreasing trend in the proportion of the 0-1 years age group (APC= -6.02 %, t =-3.77) and an increasing trend in the proportion of the 6-9 years age group (APC=16.39%, t =5.67) (both P < 0.05 ). No significant global spatial clustering was observed at the district level; however, local scattered clusters were identified in certain areas. Using the SARIMA(2,0,0)(2,0,0) 12 model, the predicted annual incidence rate of HFMD among children aged 0-9 years in Guangzhou in 2026 was 2 680.56/100 000. Conclusions From 2013 to 2025, the annual incidence rate of HFMD among children aged 0-9 years in Guangzhou exhibited a fluctuating trend; the highest incidence rate is observed in the 0-1 years age group, while the proportion of cases in the 6-9 years age group increase year by year;and local spatial clusters of abnormal distribution are identified. It is essential to enhance risk monitoring and health education in key populations and areas to mitigate the risk of infection in children.

Objective:To analyze the short-term hospital-based transmission characteristics and gene variation of Carbapenem-Resistant Klebsiella pneumoniae (CRKP) by genome-wide technique to provide evidence for transmission control. Methods:The experimental strain was derived from all the CRKP isolated in Affiliated Hospital of North China University of Science and Technology from October 2022 to December 2023. Strain identification and drug susceptibility were tested with VITEK 2-Compact automatic bacterial identification drug susceptibility analyzer or disk method, and the results were interpreted through whole genome sequencing. The ST type, carbapenem resistance gene, virulence factor, and O serotype of the collected strains were analyzed.Results:Among the 115 strains of CRKP, 94 strains were isolated from the intensive care unit (ICU), accounting for 81.7%, and 21 strains were isolated from the non-intensive care unit (NICU), accounting for 18.3%. The 115 strains of CRKP can be divided into 11 ST types, of which ST11 type was the most (54.8%, 63/115), followed by ST15 type (22.6%, 26/115) and ST5492 type (15.7%, 18/115). Type ST5492 was a new clonal group in the region. The 115 strains of CRKP could be divided into 7 O serotypes, most of which were O2a type(32.2%,37/115), followed by O5 type(30.4%,35/115) and O1 type(27.8%,32/115). The resistance genes of carbapenem antibiotics showed that there were 107 strains carrying the blaKPC-2 gene, one strain with the blaNDM-1 gene, and one strain with both the blaKPC-2 and blaNDM-13 genes. Virulence genes were detected in 55 CRKP strains (47.8%, 55/115), among which six strains detected peg-344, iucA, iroB, rmpA, and rmpA2 virulence genes (5.2%, 6/115). Four virulence genes ( peg-344, iucA, rmpA, and rmpA2) were detected in 34 strains (29.6%, 34/115). Three virulence genes ( iucA, iroB and rmpA) were detected in two strains (1.7%, 2/115). Three virulence genes ( peg-344, iucA and rmpA) were detected in one strain (0.8%, 1/115). IucA and rmpA virulence genes were detected in 12 strains (10.4%, 12/115). KPC-2_ST11_O2a, KPC-2_ST15_O1 and KPC-2_ST5492_O5 were dominant clones, and their distribution was mainly in the intensive care unit. The whole genome sequence analysis showed that there were three dominant clones, among which ST11 clones were subdivided into three dominant O serotypes, all of which were mainly in the intensive care unit. Conclusion:The popular strain in the hospital of CRKP is a KPC-2_ST11 clone group carrying iucA, rmpA/rmpA2, with cross-department transmission and mutation. ST5492 is a newly-launched clone type. The intensive care unit of hvKP carrying five virulence genes, including peg-344, should be alert to the epidemic risk of CR-hvKP outbreak.

Aim To evaluate the bioequivalence of two oral preparations of rivaroxaban tablets(test preparation T and refe-rence preparation R)in fasting/postprandibular state in healthy Chinese subjects.Methods A randomized,open,single-dose,four-cycle,completely repeated crossover experiment was used in this study.A total of 70 healthy male and female subjects were enrolled,including 38 subjects in the fasting group and 32 sub-jects in the postprandial group.Rivaroxaban tablets(2.5 mg/tablet)were taken orally once per cycle and their reference preparations were tested.The plasma rivaroxaban concentration was determined by LC-MS/MS method.The pharmacokinetic parameters of rivaroxaban tablets were calculated by WinNonlin software,and the parameters were analyzed and processed.Re-sults The PK parameters of rivaroxaban tablets and reference preparations in fasting group were as follows:Cmax was(72.48±17.08)and(66.36±15.64)μg·L-1,respectively.AUC0-t were(383.49±101.06)and(370.43±102.16)h·ng·mL-1,and AUC0-inr were(389.58±102.28)and(375.84±103.01)h·μg·L-,respectively.Main PK parameters of subjects taking rivaroxaban tablets orally after meals:Cmax were(66.48±15.64 and 60.87±13.44)μg·L-1,AUC0-t were(404.44±72.58)and(381.80±79.93)h·μg·L-1,re-spectively.AUC0_inf was(410.88±73.55)and(393.64±69.71)h·μg·L-1,respectively.Under fasting and postmeal conditions,subjects took rivaroxaban test and reference prepara-tion orally,one tablet(2.5 mg/tablet)each time.The geometric mean of the main pharmacokinetic parameters of rivaroxaban in plasma(Cmax,AUC0-t,AUC0-inf)and their corresponding values had a 90％confidence interval ranging from 80.00％to 125.00％.No serious adverse events or unexpected adverse e-vents occurred in both groups.Conclusion Rivaroxaban tablets are bioequivalent and safe in vivo under fasting and postprandial conditions.

Objective:To analyze the carriage status, subtype distribution and flanking gene sequence characteristics of oxacillinases (OXA enzyme) in 241 clinical strains of Pseudomonas aeruginosa, and assess their roles in the drug resistance of Pseudomonas aeruginosa and ability to horizontally transfer across species. Methods:Clinical P. aeruginosa isolates were collected from four hospitals in Sanya, Tangshan, Zhangjiakou, and Beijing. The prevalence of oxacillinases and their flanking gene sequences was analyzed by whole-genome sequencing (NGS) and bioinformatic approaches. Results:A total of 241 isolates of P. aeruginosa were gathered, and 35 blaOXA subtypes were identified through screening of 252 blaOXA genes. These genes were classified into three subfamilies: blaOXA-50-like (241, 95.6%), blaOXA-1-like (9, 3.6%) and blaOXA-10-like (2, 0.8%). Among these, 11 subtypes (11, 31.4%) were novel blaOXA subtypes. Nine of these belonged to the blaOXA-50-like subfamily and were designated as blaOXA-1244, blaOXA-1245, blaOXA-1246, blaOXA-1250, blaOXA-1252, blaOXA-1253, blaOXA-1254, blaOXA-1255, and blaOXA-1256. The remaining two belonged to the blaOXA-10-like subfamily and were named blaOXA-1247 and blaOXA-1248. Compared to the amino acid sequence of OXA-10, the newly identified subtype OXA-1247 exhibited a mutation at position 117, where a valine was replaced by a leucine. This change was thought to improve the enzyme′s ability to hydrolyze carbapenems. In the analysis of the flanking sequences of the blaOXA genes, Class I integrons were identified in four bacterial strains. The variable regions of these integrons carried three distinct patterns of resistance gene cassettes: aac( 6′) -Ib-blaOXA-1247-ant( 3′′) -Ia, aac( 6′) -Ib-blaOXA-1248 and aac( 6′) -Ib- blaIMP-45-blaOXA-1-catB3. Among these, the strain BJ2326 carried a class I integron that was connected to the downstream IS CR1 element to form a composite class I integron structure, additionally carrying the resistance gene blaPER-1. Out of the 223 non-wild-type P. aeruginosa strains, 127 strains exhibited non-wild-type profiles to the four beta-lactam antibiotics MEM, CAZ, FEP, and TZP, with the combination of MEM+CAZ+FEP being the most prevalent, representing 57.0% of the total. Conclusions:The blaOXA genes in 241 clinical P. aeruginosa strains showed diversity. Some blaOXA genes had a co-transfer risk with the metallo-β-lactamase resistance gene blaIMP-45. Among the 11 newly discovered blaOXA subtypes, the new subtype OXA-1247 may have carbapenemase activity and potential for horizontal transfer.