Background: Type 2 innate lymphoid cells (ILC2s) are essential for maintaining immune regulation and promoting tissue homeostasis in allergic asthma. How the development of gut microbiota on neonatal ILC2s influences allergic airway inflammation remains unclear. Here we focus on offspring ILC2 development in the context of alterations in maternal gut microbiota. Methods: C57BL/6 maternal mice were gavaged with OM-85 during pregnancy and/or lactation, ILC2-driven allergic airway inflammation in the OVA-sensitized adult offspring was observed. ILC2 development in offspring early life were investigated using recombinant (r)IL-33, rIL-25 and Bromodeoxyuridine in the vivo experiments. Further ILC2 promoting factors- IL-33 and IL-25 production in offspring early life were analysed. Finally, we examined the changes in gut microbiota and its metabolites in both dams and pups, and explored the effects of short-chain fatty acids (SCFAs) on IL-33 expression and secretion. Results: Maternal OM-85 administration restrained ILC2-driven allergic airway inflammation in the OVA-sensitized adult offspring. During ILC2 development in offspring early life, maternal OM-85 administration suppressed IL-33 and IL-25 production to inhibit ILC2 expansion and ILC2 responsiveness to alarmins, and infantile ILC2s could persist into adulthood. Maternal OM-85 administration increased SCFAs in breast milk and SCFA-producing gut probiotics (predominant Bacteroides and Blautia) in offspring, especially during pregnancy and lactation. SCFAs down-regulated IL-33 expression and reduced IL-33 secretion by inhibited gasdermin D (GSDMD) formation. Conclusion: Maternal OM-85 administration restrains ILC2-driven allergic airway inflammation in adult offspring by increasing offspring intestinal SCFAs to modulate ILC2 development at an early stage, demonstrating that the transgenerational effects of maternal OM-85 exposure on offspring innate immunity.

ABSTRACTPurposePositive airway pressure (PAP) is the primary treatment for obstructive sleep apnea (OSA). This study aims to predict the optimal PAP pressure in Chinese OSA patients by their polysomnography (PSG) variables and demographic characteristics.MethodsPatients with an apnea–hypopnea index (AHI) ≥ 15 times/h who received PAP therapy (residual AHI < 5 times/h) and underwent PSG were included in this study. Sex, age, body mass index (BMI), Epworth Sleepiness Scale (ESS), AHI, supine AHI, lowest oxygen saturation (LSaO2), percentage of total sleep time spent with SaO2 < 90% (CT90), and PAP pressure were recorded. PAP pressure and other variables were analyzed using univariate correlation and multivariate linear stepwise regression analysis.ResultsA total of 167 patients were enrolled, with 122 in the study group and 45 in the validation group. Univariate correlation analysis revealed a significant correlation between PAP pressure and age, BMI, ESS, AHI, supine AHI, LSaO2, and CT90. The multivariate linear regression analysis showed that PAP pressure was correlated with gender (b = 1.142, p = 0.032), age (b = −0.039, p = 0.005), AHI (b = 0.047, p = 0.000), and CT90 (b = 0.037, p = 0.000). The final PAP pressure prediction equation was PAPpre (cmH2O) = 8.548 + 1.142 × sex −0.039 × age + 0.047 × AHI + 0.037 × CT90 (R2 = 0.553) (male is defined as 0 and female as 1). This model accounts for 55.3% of the optimal pressure variance, and the area under the ROC curve of PAP prediction pressure is 0.7419.ConclusionPSG variables can be used to predict PAP pressure in Chinese OSA patients, but for some individuals, the prediction model is not very good. PAP is correlated with age, BMI, ESS, AHI, supine AHI, LSaO2, and percentage of total sleep time spent with SaO2 < 90% (CT90), which can be used to predict the optimal PAP pressure.

Obstructive sleep apnea-hypopnea syndrome (OSAHS) significantly impairs children’s growth and cognition. This study aims to elucidate the pathophysiological mechanisms underlying OSAHS in children, with a particular focus on the alterations in cortical information interaction during respiratory events. We analyzed sleep electroencephalography before, during, and after events, utilizing Symbolic Transfer Entropy (STE) for brain network construction and information flow assessment. The results showed a significant increase in STE after events in specific frequency bands during N2 and rapid eye movement (REM) stages, along with increased STE during N3 stage events. Moreover, a noteworthy rise in the information flow imbalance within and between hemispheres was found after events, displaying unique patterns in central sleep apnea and hypopnea. Importantly, some of these alterations were correlated with symptom severity. These findings highlight significant changes in brain region coordination and communication during respiratory events, offering novel insights into OSAHS pathophysiology in children.

Microplastics (MPs) are abundant in air, but evidence of their deposition in the respiratory tract is limited. We conducted a prospective case series to investigate the deposition of microplastics in bronchoalveolar lavage fluid (BALF) and determine the internal dose of MPs via inhalation. Eighteen never-smokers aged 32-74 years who underwent fiberoptic bronchoscopy with BALF were recruited from Zhuhai, China. Control samples were obtained by performing the same procedure using isotonic saline instead of BALF. Laser direct infrared spectroscopy combined with scanning electron microscopy detected the presence and characteristics of MPs and quantitatively analyzed the microplastic in BALF and control samples. Concentrations of total and specific MPs in BALF and control samples were compared using the Wilcox test. Thirteen types of MPs were observed in 18 BALF samples. Polyethylene (PE, 86.1%) was the most abundant in BALF, followed by poly(ethylene terephthalate) (PET, 7.5%) and polypropylene (PP, 1.9%). Compared with the control samples, BALF had significantly higher concentrations of PE (median [IQR] of BALF: 0.38 [8.05] N/g), PET (0.26 [0.54] N/g), polyurethane (0.16 [0.24] N/g), PP (0.16 [0.11] N/g), and total MPs (0.91 [6.58] N/g). The presence of MPs in BALF provides novel evidence that MPs penetrate deep into the respiratory tract.

Objective As an opportunistic pathogen, Nocardia often occurring in the immunocompromised hosts. As the unspecifc clinical presentation and low identification rate of the culture dependent methods, Nocardia infection may be under-diagnosis. Recent study have reported physicians could benefit from metagenomic next-generation sequencing (mNGS) in Nocardia diagnosis. Herein, we present patients with a positive detection of nocardiosis in mNGS, aiming to provide useful information for an differential diagnosis and patients management. Methods A total of 3756 samples detected for mNGS from March 2019 to April 2022 at the Fifth Affifiliated Hospital of Sun Yat-sen University, were screened. Clinical records, laboratory finding, CT images and mNGS results were reviewed for 19 patients who were positive for Nocardia genus. Results Samples from low respiratory tract obtained by bronchoscope took the major part of the positive (15/19). 12 of 19 cases were diagnosis as Nocardiosis Disease (ND) and over half of the ND individuals (7/12) were geriatric. Nearly all of them (10/12) were immunocompetent and 2 patients in ND group were impressively asymptomatic. Cough was the most common symptom. Nocardia cyriacigeorgica (4/12) was more frequently occurring in ND, followed by Nocardia abscessus (3/12). There are 3 individuals detected more than one kind of Nocardia species (Supplementary table 1). Except one with renal failure and one allergic to sulfamethoxazole, all of them received co-sulfonamide treatment and relieved eventually. Conclusion Our study deciphered the clinical features of patients with positive nocardiosis detected by mNGS. Greater attention should be paid to the ND that occurred in the immunocompetent host and the geriatric. Due to the difficulties in establishing diagnosis of Nocardiosis disease, mNGS should play a much more essential role for a better assessment in those intractable cases. Co-sulfonamide treatment should still be the first choice of Nocardiosis disease.

Abstract Obstructive sleep apnea hypopnea syndrome negatively affects the cognitive function of children. This study aims to find potential biomarkers for obstructive sleep apnea hypopnea syndrome in children by investigating the patterns of sleep electroencephalography networks. The participants included 16 mild obstructive sleep apnea hypopnea syndrome children, 12 severe obstructive sleep apnea hypopnea syndrome children, and 13 healthy controls. Effective brain networks were constructed using symbolic transfer entropy to assess cortical information interaction. The information flow pattern in the participants was evaluated using the parameters cross-within variation and the ratio of posterior-anterior information flow. Obstructive sleep apnea hypopnea syndrome children had a considerably higher symbolic transfer entropy in the full frequency band of N1, N2, and rapid eye movement (REM) stages (P < 0.05), and a significantly lower symbolic transfer entropy in full frequency band of N3 stage (P < 0.005), in comparison with the healthy controls. In addition, the cross-within variation of the β frequency band across all sleep stages were significantly lower in the obstructive sleep apnea hypopnea syndrome group than in the healthy controls (P < 0.05). What is more, the posterior-anterior information flowin the β frequency band of REM stage was significantly higher in mild obstructive sleep apnea hypopnea syndrome children than in the healthy controls (P < 0.05). These findings may serve as potential biomarkers for obstructive sleep apnea hypopnea syndrome in children and provide new insights into the pathophysiological mechanisms.

Abstract Background Interleukin‐33 (IL‐33) exacerbates asthma probably through type 2 innate lymphoid cells (ILC2s). Nevertheless, the association between eosinophilic asthma (EA) and ILC2s remains obscure, and the mechanisms by which IL‐33 affects ILC2s are yet to be clarified. Methods ILC2s were evaluated in peripheral blood mononuclear cells, induced sputum, and bronchoalveolar lavage fluid obtained from patients with EA. Confocal microscopy was performed to locate ILC2s in lung tissue and the mRNA expression of ILC2‐related genes was also evaluated in the EA model. The proliferation of ILC2s isolated from humans and mice was assessed following IL‐33 or anti‐IL‐33 stimulation. Results The counts, activation, and mRNA expression of relevant genes in ILC2s were higher in PBMCs and airways of patients with EA. In addition, ILC2 cell counts correlated with Asthma control test, blood eosinophil count, Fractional exhaled nitric oxide level, and predicted eosinophilic airway inflammation. IL‐33 induced stronger proliferation of ILC2s and increased their density around blood vessels in the lungs of mice with EA. Moreover, IL‐33 treatment increased the counts and activation of ILC2s and lung inflammatory scores, whereas anti‐IL‐33 antibody significantly reversed these effects in EA mice. Finally, IL‐33 enhanced PI3K and AKT protein expression in ILC2s, whereas inhibition of the PI3K/AKT pathway decreased IL‐5 and IL‐13 production by ILC2s in EA. Conclusions ILC2s, especially activated ILC2s, might be critical markers of EA. IL‐33 can induce and activate ILC2s in the lungs via the PI3K/AKT pathway in EA. Thus, using anti‐IL‐33 antibody could be a part of an effective treatment strategy for EA.

INTRODUCTION:Many scales are designed to screen for obstructive sleep apnoea-hypopnoea syndrome (OSAHS); however, there is a lack of an efficiently and easily diagnostic tool, especially for Chinese. Therefore, we conduct a cross-sectional study in China to develop and validate an efficient and simple clinical diagnostic model to help screen patients at risk of OSAHS.METHODS:This study based on 782 high-risk patients (aged >18 years) admitted to the Sleep Medicine department of the Sixth Affiliated Hospital, Sun Yat-sen University from 2015 to 2021. Totally 34 potential predictors were evaluated. We divided all patients into training and validation dataset to develop diagnostic model. The univariable and multivariable logistic regression model were used to build model and nomogram was finally built.RESULTS:Among 602 high-risk patients with median age of 46 (37, 56) years, 23.26% were women. After selecting using the univariate logistic model, 15 factors were identified. We further used the stepwise method to build the final model with five factors: age, BMI, total bilirubin levels, high Berlin score, and symptom of morning dry mouth or mouth breathing. The AUC was 0.780 (0.711, 0.848), with sensitivity of 0.848 (0.811, 0.885), specificity of 0.629 (0.509, 0.749), accuracy of 0.816 (0.779, 0.853). The discrimination ability had been verified in the validation dataset. Finally, we established a nomogram model base on the above final model.CONCLUSION:We developed and validated a predictive model with five easily acquire factors to diagnose OSAHS patient in high-risk population with well discriminant ability. Accordingly, we finally build the nomogram model.

Objective Head and neck squamous cell carcinoma (HNSCC) is a highly heterotopic malignant tumor. Alternative splicing (AS) and RNA modification have been reported to be involved in tumorigenesis. Therefore, we constructed RNA modification-associated AS (RMA-AS) signature model to predict the prognosis of HNSCC. Methods AS events and RNA-modified gene expression information were downloaded from TCGA-HNSCC database. Univariate Cox regression analysis was employed for analyzing prognosis-related AS events. RMA-AS events were obtained by constructing a coexpression network between RNA modification-associated genes and AS events using WGCNA package. The prognostic signatures were analyzed by LASSO, univariate Cox, and multivariate Cox regression. Kaplan-Meier survival analysis, proportional hazard model, and ROC curve were performed to verify the prognostic value. “ESTIMATE” R package, ssGSEA algorithm, and CIBERSORT method were used to detect immune microenvironment in HNSCC. Cytoscape was utilized to build a regulatory network of splicing factor-regulated RMA-AS. Results There were 16,574 prognostic AS events and 4 differentially expressed RNA modification-associated genes in HNSCC. Based on RMA-AS events, we obtained a risk model consisting of 14 AS events, named RMA-AS_Score. The samples were divided into RMA-AS_Score high- and RMA-AS_Score low-risk groups, according to the risk score. The RMA-AS_Score high group was related to poor prognosis. Moreover, the RMA-AS_Score signature was an independent prognostic predictor and was related to tumor grade. Meanwhile, the AUC value of RMA-AS_Score was 0.652, which is better than other clinical characteristics. Besides, a nomogram prediction model of quantitative prognosis has also been developed, which has robust effectiveness in predicting prognosis. In addition, the prognostic signature was observably related to immune microenvironment and immune checkpoint. Finally, 14 splicing factors were identified and constructed into a network of splicing factor-regulated RMA-AS. Conclusion We identified the RMA-AS signature of HNSCC. This signature could be treated as an independent prognostic predictor.

目的:探究糖皮质激素对嗜酸粒细胞哮喘(Eosinophilic asthma,EA)2型固有免疫细胞(Type 2 innate lymphoid cells,ILC2s)的影响及相关机制.方法:研究对象来自我院2021年6月至2022年6月的EA患者和健康对照(Healthy control,HC),收集相应临床基线资料并评估病情、进行血常规、肺功能等检查;应用流式细胞术检测外周血单个核细胞(Peripheral blood mononuclear cell,PBMC)ILC2s(CD45+Lin-CD127+CD294+);ELISA检测外周血IL-5、IL-13浓度.糖皮质激素治疗EA患者3月后,观察PBMC中ILC2s及 IL-5、IL-13浓度.C57BL/6J小鼠给予鸡卵清蛋白(Ovalbumin,OVA)20μg 腹腔注射致敏后用1％OVA雾化吸入激发哮喘EA模型,阴性对照(Negative control,NC)组小鼠用同等体积PBS作为对照.EA造模成功的小鼠通过流式细胞术检测血液及肺泡灌洗液中ILC2s,HE染色检测小鼠肺泡灌洗液中嗜酸性粒细胞(Eosinophil,EOS)及肺部炎症.EA小鼠经糖皮质激素处理后,检测肺部炎症情况;流式细胞术检测PBMC、肺泡灌洗液(Bronchoalveolar lavage fluid,BALF)中ILC2s;分离肺组织ILC2s,west-ern blot检测相关蛋白表达情况.结果:EA组的ILC2s比例升高,EOS升高,2型细胞因子 IL-5、IL-13增加,糖皮质激素治疗1月及3月后ILC2s比例下降,2型细胞因子IL-5、IL-13下降.与NC组小鼠比较,EA组小鼠PBMC及BALF中ILC2s升高,BALF中EOS升高,血清中2型细胞因子IL-5、IL-13升高,肺部炎症加重.糖皮质激素治疗后,肺部炎症减轻,EOS下降,ILC2s减少,2型细胞因子IL-5、IL-13下降,下调JAK/STAT蛋白.结论:在EA中,糖皮质激素通过下调JAK/STAT蛋白抑制ILC2s的功能减轻肺部炎症,为激素治疗嗜酸性粒细胞哮喘的机制提供了新方向.

BACKGROUND:There is a lack of information about regulatory T cells (Tregs) and inflammatory phenotypes in patients with asthma. In this study, we aimed to compare the characteristics of Tregs in patients with eosinophilic asthma.METHODS:Forty healthy and 120 stable asthmatic patients were recruited. Sputum and airway inflammatory phenotypes were assessed, and all patients were followed for one year. Human peripheral blood mononuclear cells (PBMCs) were collected and stimulated with phytohemagglutinin (PHA) and Dermatophagoides farina (Derp) to detect CD4+CD25+FOXP3+T cells and Foxp3 levels. Interleukin (IL)-13, IL-5, IL-17, IL-9, and interferon (IFN)-γ levels were measured.RESULTS:38.33% of patients had eosinophilic asthma, 13.33% had neutrophilic asthma, 6.67% had mixed granulocytic asthma, and 41.67% had pauci-granulocytic asthma. The eosinophilic asthma patients had a relatively high Asthma Control Test (ACT) score, an increased prediction and improvement FEV1 (%) rate, and elevated total IgE serum levels (P < 0.05). T helper cell 2 (Th2) cytokines IL-13 and IL-5 were predominantly expressed in the eosinophilic phenotype, while the Th1 cytokine IFN-γ and Th17 cytokine were found in the neutrophilic phenotype. IL-10 was significantly lower in eosinophilic asthmatic patients compared to the controls (P < 0.05). CD4+CD25+FOXP3+T cells (%Tregs) and Foxp3 gene expression in the PHA stimulated eosinophilic asthma samples were significantly lower compared to the control samples (P < 0.05). The airway inflammation phenotypes remained stable after one-year of therapy.CONCLUSION:Asthmatic patients with the eosinophilic phenotype in this study were deficient in Tregs, as characterized by a Th2 cell-biased pattern.

Tropheryma whipplei is the bacterium associated with Whipple’s disease (WD), a chronic systemic infectious disease primarily involving the gastrointestinal tract. T. whipplei can also be detected in different body site of healthy individuals, including saliva and feces. Traditionally, Tropheryma whipplei has a higher prevalence in bronchoalveolar lavage fluid (BALF) of immunocompromised individuals. Few studies have explored the significance of the detection of T. whipplei in BALF. Herein, we retrospectively reviewed 1725 BALF samples which detected for metagenomic next-generation sequencing (mNGS) from March 2019 to April 2022 in Zhuhai, China. Seventy BALs (70/1725, 4.0%) from 70 patients were positive for T. whipplei. Forty-four patients were male with an average age of 50 years. The main symptoms included cough (23/70), expectoration (13/70), weight loss (9/70), and/or dyspnea (8/70), but gastrointestinal symptoms were rare. Chronic liver diseases were the most common comorbidity (n=15, 21.4%), followed by diabetes mellitus (n=13, 18.6%). Only nine patients (12.9%) were immunocompromised. Twenty-four patients (34.3%) were finally diagnosed with reactivation tuberculosis and 15 patients (21.4%) were diagnosed with lung tumors, including 13 primary lung adenocarcinoma and two lung metastases. Fifteen patients (21.4%) had pneumonia. Among the 20 samples, T. whipplei was the sole agent, and Mycobacterium tuberculosis complex was the most common detected other pathogens. Among the non-tuberculosis patients, 31 (31/46, 67.4%) had ground glass nodules or solid nodules on chest CT. Our study indicates that T. whipplei should be considered as a potential contributing factor in some lung diseases. For non-immunocompromised patients, the detection of T. whipplei also needs attention. The mNGS technology improves the detection and attention of rare pathogens. In the future, the infection, colonization, and prognosis of T. whipplei in lung still need to be studied.

Bloodstream infections (BSIs) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) are potentially life-threatening and an urgent threat to public health. The present study aims to clarify the characteristics of carbapenemase-encoding and virulent plasmids, and their interactions with the host bacterium. A total of 425 Kp isolates were collected from the blood of BSI patients from nine Chinese hospitals, between 2005 and 2019. Integrated epidemiological and genomic data showed that ST11 and ST307 Kp isolates were associated with nosocomial outbreak and transmission. Comparative analysis of 147 Kp genomes and 39 completely assembled chromosomes revealed extensive interruption of acrR by ISKpn26 in all Kp carbapenemase-2 (KPC-2)-producing ST11 Kp isolates, leading to activation of the AcrAB-Tolc multidrug efflux pump and a subsequent reduction in susceptibility to the last-resort antibiotic tigecycline and six other antibiotics. We described 29 KPC-2 plasmids showing diverse structures, two virulence plasmids in two KPC-2-producing Kp, and two novel multidrug-resistant (MDR)-virulent plasmids. This study revealed a multifactorial impact of KPC-2 plasmid on Kp, which may be associated with nosocomial dissemination of MDR isolates.

Two multidrug-resistant (MDR) mcr-1 -harboring Klebsiella pneumoniae isolates from patients with urinary tract infections and one MDR Klebsiella quasipneumoniae isolate from a patient with bloodstream infection were identified to carry tmexCD1-toprJ1 . The addition of the efflux pump inhibitor reduced the tigecycline MIC against all three isolates by 8- to 16-fold. pKQBSI104-1 was transferred from K. quasipneumoniae to Escherichia coli J53 via conjugation.

目的 研究新型个性化可调式口腔矫治器治疗轻中度阻塞性睡眠呼吸暂停低通气综合征(OSAHS)的疗效及安全性.方法 采用多中心自身对照方法,38例轻中度OSAHS患者佩戴口腔矫治器治疗1个月,记录佩戴前、后呼吸暂停低通气指数(AHI)、最低动脉血氧饱和度(lowest SaO2,LSaO2)、鼾声指数、Epworth嗜睡量表(Epworth sleepiness score,ESS)评分、鼾声视觉模拟量表(visual analogue scale,VAS)评分及口腔矫治器使用情况.结果 37例OSAHS患者完成临床试验,有效率为67.6％ (25/37),AHI、鼾声指数、ESS评分、鼾声VAS评分下降,LSaO2上升,具有统计学意义(P＜0.05).患者主要不良反应为佩戴时轻微疼痛(1/37),佩戴时对言语功能轻微影响(4/37),佩戴时对吞咽功能轻微影响、流口水(3/37).结论 新型个性化可调式口腔矫治器治疗轻中度OSAHS具有较好的疗效及安全性,不良反应少,依从性高.

AbstractBackgroundCOVID‐19 is a highly contagious respiratory disease caused by the SARS‐CoV‐2 virus. Patients with severe disease have a high fatality rate and face a huge medical burden due to the need for invasive mechanical ventilation. Hypoxic respiratory failure is the major cause of death in these patients. There are currently no specific anti‐SARS‐CoV‐2 drugs, and the effect of corticosteroids is still controversial.MethodsThe clinical data of 102 COVID‐19 patients, including 27 patients with severe disease, were analyzed. The serum levels of total IgE and anti‐SARS‐CoV‐2 specific IgE were compared in healthy controls and COVID‐19 patients, changes in the level of anti‐SARS‐CoV‐2 specific IgE and clinical response to methylprednisolone (MP) treatment were analyzed, and the effect of high‐dose/short‐term MP therapy for patients with critical illness and respiratory failure was determined.ResultsCOVID‐19 patients had elevated serum levels of anti‐SARS‐CoV‐2 specific IgE, and patients with severe disease, especially critical illness, had even higher levels. Application of short‐term/high‐dose MP significantly reduced the level of these IgE antibodies and also blocked the progression of hypoxic respiratory failure. Hypoxic respiratory failure in patients with COVID‐19 is related to pulmonary hypersensitivity.ConclusionsHypersensitivity in the lungs is responsible for acute respiratory failure in COVID‐19 patients. Application of high‐dose/short‐term MP appears to be an effective life‐saving method for COVID‐19 patients who have hypoxic respiratory failure.

为了解河流表水中有机污染特征,于2016年9月-2017年9月连续监测了嘉陵江白庙子段水中5项水质指标的含量,并采用综合水质标识指数法进行评价.结果 表明,嘉陵江白庙子段表水中各水质指标的含量均低于《地表水环境质量标准》(GB3838-2002)中Ⅲ类水质标准值.CODMn、BOD5含量的变化规律为丰水期>平水期>枯水期;DO、NH3-N为枯水期>平水期>丰水期;丰水期水中挥发酚低于枯水期与平水期.总体来说,丰水期水质好于平水期,平水期水质好于枯水期.

Background The global dissemination of colistin resistance encoded by mcr-1 has been attributed to extensive use of colistin in livestock, threatening colistin efficacy in medicine. The emergence of mcr-1 in common pathogens, such as Escherichia coli , is of particular concern. Therefore, China banned the use of colistin in animal feed from May 1 ST 2017. We investigated subsequent changes in mcr-1 prevalence, and the genomic epidemiology of mcr-1 -positive Escherichia coli (MCRPEC). Methods Sampling was conducted pre- (October-December 2016) and post-colistin ban (October-December, 2017 and 2018, respectively). 3675 non-duplicate pig fecal samples were collected from 14 provinces (66 farms) in China to determine intervention-related changes in mcr-1 prevalence. 15193 samples were collected from pigs, healthy human volunteers, colonized and infected hospital inpatients, food and the environment in Guangzhou, to characterize source-specific mcr-1 prevalence and the wider ecological impact of the ban. From these samples, 688 MCRPEC were analyzed with whole genome sequencing (WGS), plasmid conjugation and S1-PFGE/Southern blots to characterize associated genomic changes. Findings After the ban, mcr-1 prevalence decreased significantly in national pig farms, from 45·0% (308/684 samples) in 2016, to 19·4% (274/1416) in 2018 (p<0·0001). This trend was mirrored in samples from most sources in Guangzhou (overall 19·2% [959/5003 samples] in 2016; 5·3% [238/4489] in 2018; p<0·0001). The population structure of MCRPEC was diverse (23 sequence clusters [SCs]); ST10 clonal complex isolates were predominant (247/688 [36%]). MCRPEC causing infection in hospitalized inpatients were genetically more distinct and appeared less affected by the ban. mcr-1 was predominantly found on plasmids (632/688 [92%]). Common mcr-1 plasmid types included IncX4, IncI2 and IncHI2 (502/656 [76.5%]); significant increases in IncI2-associated mcr-1 and a distinct lineage of mcr-1 -associated IncHI2 were observed post-ban. Changes in the frequency of mcr-1 -associated flanking sequences (IS Apl1 -negative MCRPEC), 63 core genome SNPs and 30 accessory genes were also significantly different after the ban, consistent with rapid genetic adaptation in response to changing selection pressures. Interpretation A rapid, ecosystem-wide, decline in mcr-1 was observed after banning the use of colistin in animal feed, with associated genetic changes in MCRPEC. Genomic surveillance is key to assessing and monitoring stewardship interventions. Funding National Natural Science Foundation of China

Background Bloodstream infection (BSI) caused by carbapenem-resistant Enterobacteriaceae are potentially life-threatening related to poorer outcomes. Colistin is considered one of the last-resort treatments against human infections caused by multidrug-resistant (MDR) Gram-negative bacteria. Therefore, emergence of strains from the blood that co-harboring mcr and carbapenem resistance genes were considered as a serious problem. Purpose In this study, two mcr-9-harboring MDR Enterobacter cloacae isolates BSI034 and BSI072 recovered from BSI patients were identified, one of which co-harbored mcr-9 and blaNDM-1. The genetic characteristics of the MDR plasmid needed to be clarified. Methods S1-PFGE and Southern blotting were conducted to determine the location of mcr-9. Whole-genome sequencing was performed to obtain the complete genome and plasmid sequences. The resistome and virulence genes of the strains, accompanied by the genetic characteristics of mcr-9- and blaNDM-1-harboring plasmids, were analyzed. Results Whole-genome sequencing showed that BSI034 harbored mcr-9-carrying IncHI2-type pBSI034-MCR9 and blaNDM-1-carrying IncX3-type pBSI034-NDM1. The 278,517 bp pBSI034-MCR9 carried mcr-9 along with the other 19 resistance genes. mcr-9 was flanked by IS903B (1057 bp) and IS26 (820 bp) in the same orientation. In addition to resistance genes, strain BSI034 also carried a chromosome-located Yersinia high-pathogenicity island, which harbored genes of yersiniabactin biosynthesis operon ybtSXQPAUTE, irp1/2, and fyuA. Conclusion We described the complete genome and mcr-9/blaNDM-1-co-harboring plasmid of E. cloacae from a BSI patient. Notable differences were observed within mosaic modules between pBSI034-MCR9 and other mcr-9-harboring plasmids due to extensive recombination via horizontal gene transfer.