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Zaifeng Si,1,2,&ast; Shengmei Zhao,3,&ast; Yingying Hao,3 Qian Wang,3 Yanfa Zhong,2 Yue Liu,3 Ran Chen,3 Yan Jin,3 Zhiming Lu1,3 1Department of Clinical Laboratory, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, People’s Republic of China; 2Department of Clinical Laboratory, Dezhou Municipal Hospital of Traditional Chinese Medicine, Dezhou, Shandong, People’s Republic of China; 3Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Yan Jin; Zhiming Lu, Email sdjinyan@163.com; luzhiming@sdu.edu.cnBackground: Enterobacter cloacae complex (ECC), which includes major nosocomial pathogens, causes urinary, respiratory, and bloodstream infections in humans, for which colistin is one of the last-line drugs.Objective: This study aimed to analyse the epidemiology and resistance mechanisms of colistin-resistant Enterobacter cloacae complex (ECC) strains isolated from Shandong, China.Methods: Two hundred non-repetitive ECC strains were collected from a tertiary hospital in Shandong Province, China, from June 2020 to June 2022. Whole-genome sequencing and bioinformatics analyses were performed to understand the molecular epidemiology of the colistin-resistant ECC strains. The nucleotide sequences of heat shock protein (hsp60) were analyzed by using BLAST search to classify ECC. The gene expression levels of ramA, soxS, acrA, acrB, phoP, and phoQ were assessed using RT-qPCR. MALDI-TOF MS was used to analyse the modification of lipid A.Results: Twenty-three colistin-resistant strains were detected among the 200 ECC clinical strains (11.5%). The hsp60 cluster analysis revealed that 20 of the 23 ECC strains belonged to heterogeneous resistance clusters. Variants of mgrB, phoPQ, and pmrAB, particularly phoQ and pmrB, were detected in the 23 ECC strains. The soxS and acrA genes were significantly overexpressed in all 23 colistin-resistant ECC strains (P < 0.05). Additionally, all 23 ECC strains contained modified lipid A related to colistin resistance, which showed five ion peaks at m/z 1876, 1920, 1955, 2114, and 2158. Among the 23 ECC strains, 6 strains possessed a phosphoethanolamine (pETN) moiety, 16 strains possessed a 4-amino-4-deoxy-L-arabinose (−L-Ara4N) moiety, and one strain had both pETN and −L-Ara4N moieties.Conclusion: This study suggests that diverse colistin resistance existed in ECC, including unknown resistance mechanisms, exist in ECC. Mechanistic investigations of colistin resistance are warranted to optimise colistin use in clinical settings and minimise the emergence of resistance.Keywords: Enterobacter cloacae complex, ECC, epidemiology, colistin, resistance mechanism

Wenjie Qu,1,2,&ast; Xinyu Wang,1,&ast; Yufei Liu,3 Jinfeng Mao,2 Mengchi Liu,4 Yaqin Zhong,1,2 Bella Gao,5 Miaomiao Zhao,1 Yuexia Gao1,2 1Department of Health Management, School of Public Health, Nantong University, Nantong, People’s Republic of China; 2Institute for Health Development, Nantong University, Nantong, People’s Republic of China; 3Faculty of Health Sciences, University of Macau, Macau, People’s Republic of China; 4National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People’s Republic of China; 5Ulink College of Suzhou Industrial Park, Suzhou, Jiangsu, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Miaomiao Zhao; Yuexia Gao, Department of Health Management, School of Public Health, Nantong University, 9 Seyuan Road, Jiangsu, 226019, People’s Republic of China, Tel +86150 0450 1812 ; +86139 6296 8819, Email zhaomiaomiao@ntu.edu.cn; yxgao@ntu.edu.cnBackground: Self-medication with antibiotics (SMA) among children is a common practice in low-income and middle-income countries, which has accelerated antibacterial abuse.Objective: This study aimed to estimate the prevalence and associated factors of SMA among children in China, including parents’ knowledge, attitudes, and practices towards antibiotic use.Methods: A cross-sectional study based on a structured questionnaire survey of parents was conducted in Nantong between July and September 2020. A total of 1699 respondents participated. Information on participants’ demographic and family characteristics, knowledge, attitudes, and practices towards antibiotics use was collected. Hierarchical binary logistic regression was used to examine the predictors of SMA among children.Results: Among 1699 participants, 23.31% practiced SMA to their children in the past year. Cough (59.6%) was the most common symptom leading to self-medication and penicillins (85.4%) were the most commonly used drugs. Hierarchical regression indicated that parents with higher level of antibiotic knowledge scores (OR=1.163, 95% CI: 1.067– 1.268) and buying antibiotics without a prescription from pharmacy (OR=1.475, 95% CI: 1.097– 1.983) were more likely to practice SMA to their children both in urban and in rural areas. Storing antibiotics at home resulted in an increased likelihood of self-medication in urban areas but not in rural areas. In addition, there was also a higher probability of non-prescribed antibiotics in children without chronic diseases (OR=1.959, 95% CI:1.072– 3.578).Conclusion: The prevalence of SMA in children is high in China. Higher knowledge scores and practices of buying and storing non-prescribed antibiotics behaviors increased parents’ antibiotic self-medication in their children. Practical and effective education intervention for children’s rational use of antibiotics is urgently strengthened.Keywords: antibiotic, self-medication, children, China, antibiotic knowledge, attitude

Dongchun Dian,1,&ast; Weilong Zhang,1,&ast; Minjun Lu,1 Yong Zhong,1 Yurong Huang,1 Guiling Chen,1 Zhangquan Chen,2 Luxin Yu,2 Jianbo Sun1 1The First Dongguan Affiliated Hospital, Guangdong Medical University, Guangdong, 523000, People’s Republic of China; 2Guangdong Medical University, Guangdong, 510000, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Jianbo Sun, Email Jianbo.sun@gdmu.edu.cnPurpose: This retrospective cohort study aimed to evaluate the clinical efficacy of ulinastatin (UTI) and azithromycin (AZM) combination therapy in treating severe pneumonia in children and its impact on inflammatory cytokines and oxidative stress.Patients and Methods: This retrospective cohort study was conducted from January 1, 2019, to January 1, 2021, involving pediatric patients diagnosed with severe mycoplasma pneumonia (SMPP). The pediatric patients were divided into two groups: those receiving UTI and AZM combination therapy (treatment group) and those receiving azithromycin alone (control group). We compared the two groups regarding clinical data, disease outcomes, inflammatory cytokines, and oxidative stress levels.Results: Baseline characteristics did not significantly differ between the two groups. UTI, in combination with AZM, significantly improved blood oxygen levels, inflammatory infection markers, and relevant clinical symptoms in patients with SMPP on the 3rd day of treatment. Additionally, it significantly reduced the levels of inflammatory cytokines TNF-a, IL-6, IL-1β, and IL-10, as well as oxidative stress markers GSH and SOD.Conclusion: Combining UTI and AZM can rapidly alleviate clinical symptoms and effectively control the progression of patients with SMPP. Therefore, this treatment approach deserves consideration for clinical promotion and utilization.Keywords: severe mycoplasma pneumonia, ulinastatin, azithromycin, pediatrics

Jieying Wang,&ast; Chunchun Yu,&ast; Yuni Xu,&ast; Zhuolin Chen, Wenhua Qiu, Shaowen Chen, Hua Pei, Yeteng Zhong Department of Clinical Laboratory, The Second Affiliated Hospital of Hainan Medical University, Haikou, 570216, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Yeteng Zhong, Department of Clinical Laboratory, The Second Affiliated Hospital of Hainan Medical University, Haikou, 570216, People’s Republic of China, Email zhongyeteng@163.comPurpose: Given the high burden of Tuberculosis (TB) in China, the prevalence of multidrug-resistant tuberculosis (MDR-TB) is significant. Whole-genome sequencing (WGS) of Mycobacterium tuberculosis (MTB) enables the identification of lineages, drug-resistant mutations, and transmission patterns, offering valuable insights for TB control, clinical diagnosis, and treatment.Methods: We collected 202 MDR-MTB strains from 3519 suspected pulmonary TB patients treated at The Second Affiliated Hospital of Hainan Medical University between July 2019 and June 2021. Proportional drug-susceptibility testing was performed using 8 common anti-tuberculosis drugs. Subsequently, the genotypic drug resistance and genetic characteristics were analyzed by the WGS.Results: Lineages are identified by TB-profiler revealed 202 MDR-MTB strains, showcasing three predominant lineages, with lineage 2 being the most prevalent. Close genomic relatedness analysis and evidence of MTB transmission led to the formation of 15 clusters comprising 42 isolates, resulting in a clustering rate of 20.8%. Novelty, lineage 2.1 (non-Beijing) accounted for 27.2% of the MDR-MTB strains, which is rare in China and Neighboring countries. Regarding first-line anti-TB drugs, genes associated with rifampicin resistance, primarily the rpoB gene, were detected in 200 strains (99.0%). Genes conferring resistance to isoniazid, ethambutol, and streptomycin were identified in 191 (94.5%), 125 (61.9%), and 100 (49.5%) strains, respectively. Among the second-line drugs, 97 (48.0%) strains exhibited genes encoding resistance to fluoroquinolones. Comparing the results to phenotypic drug susceptibility-based testing, the sensitivity of WGS for detecting resistance to each of the six drugs (rifampicin, isoniazid, ethambutol, ofloxacin, kanamycin, capreomycin) was 90% or higher. With the exception of ethambutol, the specificity of WGS prediction for the remaining drugs exceeded 88%.Conclusion: Our study provides crucial insights into genetic mutation types, genetic diversity, and transmission of MDR-MTB on Hainan Island, serving as a significant reference for MDR-MTB surveillance and clinical decision-making.Keywords: tuberculosis, MDR-TB, whole-genome sequencing, WGS, genetic diversity, Hainan Island, China

Zhuzhu Qin,1,&ast; Xinxin Ye,2,&ast; Huanju Liu,3 Yining Tao,4 Xutong Zheng,1 Yanxia Zhong,5 Danfeng Chen,1 Wan Ye,6 Chenju Zhan7 1School of Nursing, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China; 2Department of Sports and Exercise Science, College of Education, Zhejiang University, Hangzhou, Zhejiang, China; 3Women’s Hospital and Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, China; 4Department of Global Public Health, Karolinska Institute, Stockholm, Sweden; 5Department of Nursing, Shijiazhuang Medical College, Shijiazhuang, China; 6Department of Nursing, Xiamen Medical College, Xiamen, Fujian, China; 7Department of Nursing, Mindong Hospital Affiliated to Fujian Medical University, Ningde, China&ast;These authors contributed equally to this workCorrespondence: Wan Ye, Department of Nursing, Xiamen Medical College, Xiamen, Fujian, China, Tel +86 13806086169, Email 200600010142@xmmc.edu.cn Chenju Zhan, Department of Nursing, Mindong Hospital Affiliated to Fujian Medical University, No. 89 HeShan Road, Fuan City, Fujian Province, 355000, China, Tel +86 13809562183, Email zhanchenju@yeah.netObjective: This study investigated factors influencing the knowledge, attitudes, practice profiles, and vaccination intentions among Chinese nursing students and nursing interns toward the coronavirus disease (COVID-19) vaccination.Materials and Methods: The multicenter cross-sectional study was based on a self-reported questionnaire collecting information among nursing students and nursing interns from three major geographic regions of China, and the sample was selected by consecutive sampling. The questionnaire was developed by knowledge, attitudes, and practice (KAP) theory. Univariate and multivariate logistic regression were used for statistical analysis.Results: A total of 3180 nursing students and interns (effective rate: 99.8%) from six Chinese provinces were polled. The vaccine hesitation rate was 9.65% (307/3180), 2230 participants (70.1%) had gotten at least one dose of the vaccine, and 643 participants (67.7%) had indicated a readiness to be vaccinated. The results showed that older age, higher academic background, perfect vaccine management, others’ recommendations, influenza vaccination history, epidemic under control, knowledge of vaccines or intervals, and vaccine knowledge training were associated with higher vaccination rates. Conversely, vaccine hesitancy was caused by a perceived lack of physical need, uncertainty about vaccination requirements, and fear of vaccination.Conclusion: This study provided population-based estimates of COVID-19 vaccine uptake intention among mainland Chinese nursing students and interns. Factors such as age, education, vaccine knowledge, and attitudes influence COVID-19 vaccine behaviour. Relevant authorities should understand the barriers to COVID-19 vaccination from knowledge, attitude and practice, which is significant for formulating effective response strategies in future global public health crises.Graphical Abstract: Keywords: COVID-19, vaccine, knowledge, attitudes, practice, nursing students and interns

Juan Guo,1,&ast; Zhiyu Pan,1,&ast; Lvyuan Fan,1 Yilin Zhong,1 Rui Pang,2 Yubin Su1 1Department of Cell Biology & Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, MOE Key Laboratory of Tumor Molecular Biology, Guangdong Provincial Key Laboratory of Bioengineering Medicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, People’s Republic of China; 2Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Yubin Su, Email suyb7@jnu.edu.cnBackground: The issue of methicillin-resistant Staphylococcus aureus (MRSA) resistant to many antibiotics and causing serious infectious diseases is a growing healthcare concern.Purpose: In recent years, exogenous administration of metabolites in combination with antibiotics can re-sensitize resistant bacteria to antibiotics; however, their effects vary, and their underlying mechanism of action remains elusive.Methods: We assessed the bactericidal effects of the three amino acids in combination with gentamicin in vitro and in vivo. Subsequently, we explored the role of these amino acids on the metabolomics of MRSA using Liquid chromatography-tandem mass spectrometry (LC-MS/MS). Furthermore, we performed the downstream analyses using MetaboAnalyst and Interactive Pathways Explorer.Results: Exogenous threonine showed the best bactericidal efficacy with gentamicin, followed by glycine, wherein serine had no effect. Amino acid treatments mainly up-regulated the metabolites, increased the amino acid abundance, and significantly activated metabolisms; these effects were consistent with the bactericidal efficacy of the three amino acids. Most amino acids participated in the tricarboxylic acid cycle, and threonine supplementation increased the activities of citrate synthase, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase, whereas glycine increased activities of citrate synthase and α-ketoglutarate dehydrogenase, and serine did not affect the activities of any of the three key enzymes. We identified 24 biomarkers in the three groups, among which glutamic acid and cysteine showed a gradient decrease and increase, respectively. Subsequent analyses revealed that glutamic acid but not cysteine promoted the bactericidal effect of gentamicin synergistically.Conclusion: Threonine has the best synergistic effect in reversing bacterial resistance compared to glycine and serine. We show that different amino acids combined with an antibiotic mainly affect amino acid metabolism and act via different metabolic regulatory mechanisms, which could help develop effective strategies for tackling MRSA infections.Keywords: methicillin-resistant Staphylococcus aureus, metabolomics, gentamicin, amino acid, metabolic regulation

Jieying Wang,&ast; Zhuoling Chen,&ast; Yuni Xu, Wenhua Qiu, Shaowen Chen, Hua Pei, Yeteng Zhong Department of Clinical Laboratory, The Second Affiliated Hospital Hainan Medical University, Haikou, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Yeteng Zhong; Hua Pei, Department of Clinical Laboratory, The Second Affiliated Hospital Hainan Medical University, Haikou, People’s Republic of China, Email zhongyeteng@163.com; phzmh61@aliyun.comBackground: China has seen a drastic increase in the incidence of non-tuberculous mycobacteria (NTM) infection, which is a notable public health issue. Due to a lack of reliable epidemiological surveillance information, there is a need to gather accurate epidemiological and surveillance data, which can help clinicians effectively treat NTM patients. Moreover, drug susceptibility testing for NTM is not frequently performed in China. This retrospective study, therefore, determined the prevalence and resistance characteristics of NTM to provide a reference to control the NTM epidemic.Methods: Sputum, alveolar lavage fluid, and other respiratory specimens were collected from 3025 patients with suspected pulmonary tuberculosis attending The Second Affiliated Hospital of Hainan Medical University from January 2014 to December 2021. Strain identification and species distribution of NTM were performed by DNA chip technology and gene sequencing, and the drug resistance of NTM isolates was evaluated by calculating the minimum inhibitory concentration through antimicrobial susceptibility testing for NTM.Results: From 2014 to 2021, 373 strains of NTM were isolated and identified from respiratory specimens of 3025 suspected tuberculosis patients. Except in 2014, NTM-infected patients accounted for more than 10% of suspected tuberculosis patients in other years. The median age of patients with NTM infection was 62.0 years (53.0, 71.0), and the male-to-female ratio among these patients was 0.79:1. Among culture-positive strains, 12.3% (373/3040; 95% CI 11.1– 13.4%) were identified as NTM comprising forty species of NTM. The forty species of NTM included 23 slow-growing mycobacteria (SGM) and 17 rapidly-growing mycobacteria (RGM). Among the NTM isolates, 58.7% (219/373; 95% CI 53.7– 63.7%) were SGM and 41.3% (154/373; 95% CI 36.3– 46.3%) were RGM. M.avium complex(MAC)(41.3%; 95% CI 36.3– 46.3%) and M.abscessus complex (MABC)(33.2%; 95% CI 28.4– 38.0%) were the most frequently detected species, followed by M.simiae Complex (11.8%; 95% CI 8.5– 15.1%), M.fortuitum group (5.1%; 95% CI 2.9– 7.3%), and others. Drug sensitivity test results showed that most of the NTM isolates were susceptible to amikacin and clarithromycin with a drug resistance rate of less than 10%. However, clarithromycin could induce drug resistance, followed by linezolid and moxifloxacin, and their drug resistance rate was less than 50%.Conclusion: During 2014– 2021, the number of NTM isolates detected in the respiratory specimens of the study patients in The Second Affiliated Hospital of Hainan Medical University increased year by year. M. intracellulare is the most common pathogenic NTM species, and there is a high incidence of NTM infection on Hainan Island. Our findings might be of great importance for diagnosing and treating this patient population in Hainan.Keywords: Mycobacterium, non-tuberculous mycobacteria, pulmonary disease, drug resistance

Jinyan Lin,&ast; Yu Zhang,&ast; Chongxi Bao, Huasong Lu, Yun Zhong, Chuanfeng Huang, Qiuping Huang, Dezhen Wang, Jing Luo, Ke Wang, Jinliang Kong Pulmonary and Critical Care Medicine Ward, Guangxi Medical University First Affiliated Hospital, Nanning, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Jinliang Kong; Ke Wang, Pulmonary and Critical Care Medicine Ward, Guangxi Medical University First Affiliated Hospital, No. 6 Shuangyong Road, Nanning, 530021, People’s Republic of China, Email kjl071@126.com; 497256113@qq.comBackground: Streptococcus constellatus, a commensal, plays an important role in purulent infections. It has been reported as aggressive pathogen causing pleural empyema. But the role of S. constellatus in empyema has not been taken seriously. There are no studies about clinical characteristics of empyema caused by S. constellatus domestically and abroad. This study aimed to explore the clinical features and management of empyema caused by S. constellatus.Methods: A retrospective review of 9 patients diagnosed with empyema caused by S. constellatus in a hospital between January 2010 and August 2021 was performed.Results: S. constellatus empyema were mostly seen in old males (66.7%) with comorbid diseases. The high-risk factors include diabetes mellitus, oral infection, and oral surgery. All were unilateral encapsulated empyema (right-side, 55.6%), diagnosed with pneumonia (bilateral pneumonia, 88.9%; ipsilateral lung abscess, 44.4%). 33.3% of patients had S. constellatus and anaerobes co-isolated. S. constellatus were sensitive to penicillin G, linezolid, levofloxacin, vancomycin, ceftriaxone, and chloramphenicol, resistant to erythromycin, tetracycline, and clindamycin. 33.3% of the patients needed ventilator support. The primary treatment to S. constellatus empyema was timely pus drainage, intravenous antibiotics, and enough nutrition support, intrapleural fibrinolytics and surgery (VAST recommended first) in necessity.Conclusion: S. constellatus may cause pneumonia and lung abscess first and then spread to cause empyema mainly in old males with comorbid diseases. S. constellatus often co-isolated with anaerobes in empyema. Antibiotics should cover simultaneously both S. constellatus and anaerobes.Keywords: S. constellatus, empyema, clinical features, anaerobes

Min Zhang,1,2 Jia Li,3 Yuemei Lu,4 Weiyuan Wu,4 Jinsong Wu,4 Yanji Xu,1,5 Yuxin Zhong,1,2 Shiyi Liu,1,2 Chuchu Lin,6 Shuye Xu,3 Dandan Chen,1,2 Xuefeng Gao,7 Yutian Luo,8 Huaisheng Chen,8 Xueyan Liu,8 Wei Huang1,2 1Shenzhen People’s Hospital, Shenzhen Institute of Respiratory Diseases, Shenzhen, Guangdong, People’s Republic of China; 2Bacteriology & Antibacterial Resistance Surveillance Laboratory, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, People’s Republic of China; 3Department of Nosocomial Infection Control, Bengbu Third People’s Hospital, Bengbu, People’s Republic of China; 4Department of Clinical Microbiology, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, People’s Republic of China; 5Nanshan District Center of Chronic Disease Control, Shenzhen, People’s Republic of China; 6Department of Nosocomial Infection Control, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, People’s Republic of China; 7Department of Gastroenterology and Hepatology, Shenzhen University General Hospital, Shenzhen, People’s Republic of China; 8Department of Intensive Care Unit, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, People’s Republic of ChinaCorrespondence: Wei HuangBacteriology & Antibacterial Resistance Surveillance Laboratory, Shenzhen Institute of Respiratory Diseases, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University The First Affiliated Hospital, Southern University of Science and Technology), No. 1017 Dongmen North Road, Shenzhen People’s Hospital, Shenzhen, 518020, Guangdong, People’s Republic of ChinaTel +86 7522942513Fax +86 7522942514Email whuang_sz@163.comBackground: ST11 is the most prevalent sequence type of clinical Klebsiella pneumoniae in China.Methods: We investigated the characteristics of the ST11 subclones using core genome multi-locus sequence typing (cgMLST). Ninety-three carbapenemase-producing K. pneumoniae isolates were collected at Shenzhen People’s Hospital. Then, whole-genome sequencing and cgMLST were used to discriminate apparent subclones within the ST11 group.Results: We analyzed the prevalence and genetic relationships of these subclones. ST11 and K. pneumoniae carbapenemase (KPC-2) were the predominant genotype and carbapenemase, respectively, in the clinical carbapenemase-producing K. pneumoniae strains. cgMLST scheme genotyping divided the ST11 group into two clades across seven complex types (CTs). CT1313 was the most prevalent subclone. The deletion of galF and a high frequency of SNPs in genes associated with the stress- and SOS-responses were found in CT1291 and CT2405 over time, respectively.Conclusion: Our results indicated that the subclones of the ST11 group had different patterns of prevalence. Highly discriminatory genotyping techniques, such as cgMLST scheme, should be used in further molecular epidemiology investigations.Keywords: Klebsiella pneumoniae, whole genome sequencing, cgMLST, ST11, carbapenem-resistance

Na Pei,1– 3,* Qingxia Liu,4,* Xinyi Cheng,1,5,6,* Tianzhu Liang,1,3 Zijuan Jian,4 Siyi Wang,4 Yiming Zhong,4 Jingxuan He,4 Mao Zhou,4 Karsten Kristiansen,1,2 Weijun Chen,1,6,7 Wenen Liu,4 Junhua Li1,3 1BGI-Shenzhen, Shenzhen, 518083, People’s Republic of China; 2Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark; 3Shenzhen Key Laboratory of Unknown Pathogen Identification, Shenzhen, 518083, People’s Republic of China; 4Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, People’s Republic of China; 5School of Biology and Biological Engineering, South China University of Technology, Guangzhou, People’s Republic of China; 6BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, 518083, People’s Republic of China; 7BGI PathoGenesis Pharmaceutical Technology, Shenzhen, People’s Republic of China*These authors contributed equally to this workCorrespondence: Junhua LiBGI-Shenzhen, Shenzhen, 518083, People’s Republic of ChinaTel +86 13929566296Email lijunhua@genomics.cnWenen LiuDepartment of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, People’s Republic of ChinaTel +86 13973128689Email wenenliu@163.comPurpose: Multi-drug resistant Klebsiella pneumoniae (MDR KP) is spreading worldwide and has posed a huge medical burden to public health. However, studies on drug resistance surveillance of KP, especially MDR KP, with a large longitudinal sample size in a tertiary hospital are rare. This study aims to investigate phenotypic epidemiology characteristics of 4128 KP isolates in a Chinese tertiary hospital covering a period of 5 years.Methods: All the KP clinical isolates were retrospectively collected from a tertiary hospital in Hunan province of China from Jan 5, 2013 to Jul 24, 2018. All the isolates were identified by MALDI-TOF MS analysis. Twenty-four antimicrobial agents were tested by antimicrobial susceptibility testing. Fisher exact test and logistic regression were used to analyze the association between clinical factors and antimicrobial non-susceptibility for seven second-choice antimicrobials.Results: A total of 4128 KP isolates were collected in our study. The non-susceptible rates (NSRs) to ertapenem, imipenem and tigecycline increased considerably from 2013 to 2018 (13.6% to 28.6%, 10.1% to 28.9%, 10.8% to 46.5%, respectively). Amikacin presents the lowest NSR among 3 aminoglycosides (3.8– 22.8%). The multi-drug NSRs among KP isolates to second-choice antimicrobials (88.6– 100%) were higher than to all drugs (68.0%). The NSRs varied significantly among departments and sample sources. Higher ETP/IPM/AK NSRs (39.8/39.7/30.6%) were observed in Intensive Care Unit, and ETP/IPM non-susceptible isolates tended to distribute in cerebrospinal fluid. From 2015 to 2017, the NSRs of ETP, IPM, and AK showed an opposite trend of seasonal fluctuations to SXT.Conclusion: Higher multi-drug resistance (MDR) rates were observed in KP isolates to second-choice antimicrobials than to others, among which MDR rates to carbapenems or AK are the highest. A unique pattern of MIC and time distributions of MDR were observed. Clinical factors including gender were correlated with MDR rates of KP. Isolates in ICU and CSF showed higher NSRs in carbapenems which should be paid more attention to, and temporal distribution of NSRs was observed.Keywords: Klebsiella pneumoniae, drug resistance, NSR, phenotypic epidemiology

Qiuyang Deng,1,* Jinyong Zhang,2,* Min Zhang,1 Zhou Liu,3 Yuxin Zhong,1 Shiyi Liu,1 Ruiqin Cui,1 Yun Shi,2 Hao Zeng,2 Xiyao Yang,3 Chuchu Lin,4 Yutian Luo,5 Huaisheng Chen,5 Weiyuan Wu,6 Jinsong Wu,6 Tianle Zhang,7 Yuemei Lu,6 Xueyan Liu,5 Quanming Zou,2 Wei Huang1 1Bacteriology & Antibacterial Resistance Surveillance Laboratory, Shenzhen Institute of Respiratory Diseases, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518020, People’s Republic of China; 2National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Army Medical University, Chongqing, People’s Republic of China; 3Second Affiliated Hospital of Anhui Medical University, Hefei, People’s Republic of China; 4Department of Nosocomial Infection Control, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518020, People’s Republic of China; 5Intensive Care Unit, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518020, People’s Republic of China; 6Department of Clinical Microbiology, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518020, People’s Republic of China; 7Guangdong Medical University, Dongguan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Wei HuangBacteriology & Antibacterial Resistance Surveillance Laboratory, Shenzhen Institute of Respiratory Diseases, Shenzhen People’s Hospital, The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518020, People’s Republic of ChinaTel +86 7522942513Fax +86 7522942514Email whuang_sz@163.comQuanming Zou National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical PharmacyCollege of Pharmacy, Army Medical University, Chongqing 400038, People’s Republic of ChinaTel/Fax +86 2368752316Email qmzou2007@163.comObjective: We aimed to establish a tool for rapid identification of KL49 Acinetobacter baumannii.Methods: Based on the capsular polysaccharide (CPS) synthesis genes database, we investigated the distribution of K locus type 49 (KL49) genes in other KL types and established a rapid identification method for KL49. We collected 61 clinical carbapenem-resistant A. baumannii (CRAB) strains, identified KL49 by gtr100 detection, and used whole genome sequencing (WGS) for verification. A mouse pneumonia model was used to confirm the hypervirulence phenotype. We tested the presence of gtr100 gene in 165 CRAB strains from three provinces in China and evaluated the correlation of gtr100 carrying CRAB infection with mortality.Results: The gtr100 gene is the CPS synthesis gene found only in KL49. We screened out nine WGS-validated KL49 strains from 61 CRAB clinical strains using polymerase chain reaction (PCR) to detect the gtr100 gene. The survival rates of KL49 strains were significantly lower than nonKL49 strains in a mouse pneumonia model. The survival rates of LAC-4 gtr100 knockout strain decreased significantly. Analysis of phylogenetics showed the worldwide spread of KL49 A. baumannii. Infection of gtr100 carrying CRAB is an independent risk for mortality (OR, 10.76; 95%CI: 3.08– 37.55; p< 0.001).Conclusion: The hypervirulence phenotype of KL49 CRAB and the association with mortality highlight the urgent need for implementing control measures. The rapid identification assay has the potential to facilitate early medical intervention and worldwide surveillance.Keywords: Acinetobacter baumannii, hypervirulent, K locus, Kaptive, mortality