1.Effects of MTHFR and GGH gene polymorphisms on plasma concentrations and toxicity following high-dose methotrexate therapy in children with acute lymphoblastic leukemia.
Lin-Xiao TENG ; Qi AN ; Lei WANG ; Nan WANG ; Qing-Ling KONG ; Rui HAN ; Yuan WANG ; Lu LIU ; Yan WANG ; Shu-Mei XU ; Kun-Peng SHI ; Fang-Shan QIU ; Xi-Xi DU ; Jin-Rui SHI
Chinese Journal of Contemporary Pediatrics 2025;27(7):802-807
OBJECTIVES:
To investigate the effects of methylenetetrahydrofolate reductase (MTHFR) rs1801133 and γ-glutamyl hydrolase (GGH) rs11545078 gene polymorphisms on plasma concentrations and toxicity following high-dose methotrexate (MTX) therapy in children with acute lymphoblastic leukemia (ALL).
METHODS:
Children with ALL treated at the Xuzhou Children's Hospital of Xuzhou Medical University from January 2021 to April 2024 were selected for this study. Genotypes of MTHFR rs1801133 and GGH rs11545078 were determined using multiplex polymerase chain reaction. MTX plasma concentrations were measured by enzyme-multiplied immunoassay technique, and toxicity was graded according to the Common Terminology Criteria for Adverse Events version 5.0. The relationships between MTHFR rs1801133 and GGH rs11545078 genotypes and both MTX plasma concentrations and associated toxicities were analyzed.
RESULTS:
In the low-risk ALL group, the MTHFR rs1801133 genotype was associated with increased MTX plasma concentrations at 72 hours (P<0.05). In the intermediate- to high-risk group, the MTHFR rs1801133 genotype was associated with increased MTX plasma concentrations at 48 hours (P<0.05), and the GGH rs11545078 genotype was associated with increased MTX plasma concentrations at 48 hours (P<0.05). In the intermediate- to high-risk group, the MTHFR rs1801133 genotype was associated with the occurrence of reduced hemoglobin (P<0.05), and the GGH rs11545078 genotype was associated with the occurrence of thrombocytopenia (P<0.05).
CONCLUSIONS
Detection of MTHFR rs1801133 and GGH rs11545078 genotypes can be used to predict increased MTX plasma concentrations and the occurrence of toxic reactions in high-dose MTX treatment of ALL, enabling timely interventions to enhance safety.
Humans
;
Methotrexate/toxicity*
;
Methylenetetrahydrofolate Reductase (NADPH2)/genetics*
;
Precursor Cell Lymphoblastic Leukemia-Lymphoma/blood*
;
Male
;
Female
;
Child
;
Child, Preschool
;
gamma-Glutamyl Hydrolase/genetics*
;
Antimetabolites, Antineoplastic/adverse effects*
;
Infant
;
Polymorphism, Genetic
;
Adolescent
;
Genotype
;
Polymorphism, Single Nucleotide
2.Expert consensus on apical microsurgery.
Hanguo WANG ; Xin XU ; Zhuan BIAN ; Jingping LIANG ; Zhi CHEN ; Benxiang HOU ; Lihong QIU ; Wenxia CHEN ; Xi WEI ; Kaijin HU ; Qintao WANG ; Zuhua WANG ; Jiyao LI ; Dingming HUANG ; Xiaoyan WANG ; Zhengwei HUANG ; Liuyan MENG ; Chen ZHANG ; Fangfang XIE ; Di YANG ; Jinhua YU ; Jin ZHAO ; Yihuai PAN ; Shuang PAN ; Deqin YANG ; Weidong NIU ; Qi ZHANG ; Shuli DENG ; Jingzhi MA ; Xiuping MENG ; Jian YANG ; Jiayuan WU ; Yi DU ; Junqi LING ; Lin YUE ; Xuedong ZHOU ; Qing YU
International Journal of Oral Science 2025;17(1):2-2
Apical microsurgery is accurate and minimally invasive, produces few complications, and has a success rate of more than 90%. However, due to the lack of awareness and understanding of apical microsurgery by dental general practitioners and even endodontists, many clinical problems remain to be overcome. The consensus has gathered well-known domestic experts to hold a series of special discussions and reached the consensus. This document specifies the indications, contraindications, preoperative preparations, operational procedures, complication prevention measures, and efficacy evaluation of apical microsurgery and is applicable to dentists who perform apical microsurgery after systematic training.
Microsurgery/standards*
;
Humans
;
Apicoectomy
;
Contraindications, Procedure
;
Tooth Apex/diagnostic imaging*
;
Postoperative Complications/prevention & control*
;
Consensus
;
Treatment Outcome
3.Expert consensus on pulpotomy in the management of mature permanent teeth with pulpitis.
Lu ZHANG ; Chen LIN ; Zhuo CHEN ; Lin YUE ; Qing YU ; Benxiang HOU ; Junqi LING ; Jingping LIANG ; Xi WEI ; Wenxia CHEN ; Lihong QIU ; Jiyao LI ; Yumei NIU ; Zhengmei LIN ; Lei CHENG ; Wenxi HE ; Xiaoyan WANG ; Dingming HUANG ; Zhengwei HUANG ; Weidong NIU ; Qi ZHANG ; Chen ZHANG ; Deqin YANG ; Jinhua YU ; Jin ZHAO ; Yihuai PAN ; Jingzhi MA ; Shuli DENG ; Xiaoli XIE ; Xiuping MENG ; Jian YANG ; Xuedong ZHOU ; Zhi CHEN
International Journal of Oral Science 2025;17(1):4-4
Pulpotomy, which belongs to vital pulp therapy, has become a strategy for managing pulpitis in recent decades. This minimally invasive treatment reflects the recognition of preserving healthy dental pulp and optimizing long-term patient-centered outcomes. Pulpotomy is categorized into partial pulpotomy (PP), the removal of a partial segment of the coronal pulp tissue, and full pulpotomy (FP), the removal of whole coronal pulp, which is followed by applying the biomaterials onto the remaining pulp tissue and ultimately restoring the tooth. Procedural decisions for the amount of pulp tissue removal or retention depend on the diagnostic of pulp vitality, the overall treatment plan, the patient's general health status, and pulp inflammation reassessment during operation. This statement represents the consensus of an expert committee convened by the Society of Cariology and Endodontics, Chinese Stomatological Association. It addresses the current evidence to support the application of pulpotomy as a potential alternative to root canal treatment (RCT) on mature permanent teeth with pulpitis from a biological basis, the development of capping biomaterial, and the diagnostic considerations to evidence-based medicine. This expert statement intends to provide a clinical protocol of pulpotomy, which facilitates practitioners in choosing the optimal procedure and increasing their confidence in this rapidly evolving field.
Humans
;
Calcium Compounds/therapeutic use*
;
Consensus
;
Dental Pulp
;
Dentition, Permanent
;
Oxides/therapeutic use*
;
Pulpitis/therapy*
;
Pulpotomy/standards*
4.Expert consensus on intentional tooth replantation.
Zhengmei LIN ; Dingming HUANG ; Shuheng HUANG ; Zhi CHEN ; Qing YU ; Benxiang HOU ; Lihong QIU ; Wenxia CHEN ; Jiyao LI ; Xiaoyan WANG ; Zhengwei HUANG ; Jinhua YU ; Jin ZHAO ; Yihuai PAN ; Shuang PAN ; Deqin YANG ; Weidong NIU ; Qi ZHANG ; Shuli DENG ; Jingzhi MA ; Xiuping MENG ; Jian YANG ; Jiayuan WU ; Lan ZHANG ; Jin ZHANG ; Xiaoli XIE ; Jinpu CHU ; Kehua QUE ; Xuejun GE ; Xiaojing HUANG ; Zhe MA ; Lin YUE ; Xuedong ZHOU ; Junqi LING
International Journal of Oral Science 2025;17(1):16-16
Intentional tooth replantation (ITR) is an advanced treatment modality and the procedure of last resort for preserving teeth with inaccessible endodontic or resorptive lesions. ITR is defined as the deliberate extraction of a tooth; evaluation of the root surface, endodontic manipulation, and repair; and placement of the tooth back into its original socket. Case reports, case series, cohort studies, and randomized controlled trials have demonstrated the efficacy of ITR in the retention of natural teeth that are untreatable or difficult to manage with root canal treatment or endodontic microsurgery. However, variations in clinical protocols for ITR exist due to the empirical nature of the original protocols and rapid advancements in the field of oral biology and dental materials. This heterogeneity in protocols may cause confusion among dental practitioners; therefore, guidelines and considerations for ITR should be explicated. This expert consensus discusses the biological foundation of ITR, the available clinical protocols and current status of ITR in treating teeth with refractory apical periodontitis or anatomical aberration, and the main complications of this treatment, aiming to refine the clinical management of ITR in accordance with the progress of basic research and clinical studies; the findings suggest that ITR may become a more consistent evidence-based option in dental treatment.
Humans
;
Tooth Replantation/methods*
;
Consensus
;
Periapical Periodontitis/surgery*
5.Expert consensus on the diagnosis and treatment of cemental tear.
Ye LIANG ; Hongrui LIU ; Chengjia XIE ; Yang YU ; Jinlong SHAO ; Chunxu LV ; Wenyan KANG ; Fuhua YAN ; Yaping PAN ; Faming CHEN ; Yan XU ; Zuomin WANG ; Yao SUN ; Ang LI ; Lili CHEN ; Qingxian LUAN ; Chuanjiang ZHAO ; Zhengguo CAO ; Yi LIU ; Jiang SUN ; Zhongchen SONG ; Lei ZHAO ; Li LIN ; Peihui DING ; Weilian SUN ; Jun WANG ; Jiang LIN ; Guangxun ZHU ; Qi ZHANG ; Lijun LUO ; Jiayin DENG ; Yihuai PAN ; Jin ZHAO ; Aimei SONG ; Hongmei GUO ; Jin ZHANG ; Pingping CUI ; Song GE ; Rui ZHANG ; Xiuyun REN ; Shengbin HUANG ; Xi WEI ; Lihong QIU ; Jing DENG ; Keqing PAN ; Dandan MA ; Hongyu ZHAO ; Dong CHEN ; Liangjun ZHONG ; Gang DING ; Wu CHEN ; Quanchen XU ; Xiaoyu SUN ; Lingqian DU ; Ling LI ; Yijia WANG ; Xiaoyuan LI ; Qiang CHEN ; Hui WANG ; Zheng ZHANG ; Mengmeng LIU ; Chengfei ZHANG ; Xuedong ZHOU ; Shaohua GE
International Journal of Oral Science 2025;17(1):61-61
Cemental tear is a rare and indetectable condition unless obvious clinical signs present with the involvement of surrounding periodontal and periapical tissues. Due to its clinical manifestations similar to common dental issues, such as vertical root fracture, primary endodontic diseases, and periodontal diseases, as well as the low awareness of cemental tear for clinicians, misdiagnosis often occurs. The critical principle for cemental tear treatment is to remove torn fragments, and overlooking fragments leads to futile therapy, which could deteriorate the conditions of the affected teeth. Therefore, accurate diagnosis and subsequent appropriate interventions are vital for managing cemental tear. Novel diagnostic tools, including cone-beam computed tomography (CBCT), microscopes, and enamel matrix derivatives, have improved early detection and management, enhancing tooth retention. The implementation of standardized diagnostic criteria and treatment protocols, combined with improved clinical awareness among dental professionals, serves to mitigate risks of diagnostic errors and suboptimal therapeutic interventions. This expert consensus reviewed the epidemiology, pathogenesis, potential predisposing factors, clinical manifestations, diagnosis, differential diagnosis, treatment, and prognosis of cemental tear, aiming to provide a clinical guideline and facilitate clinicians to have a better understanding of cemental tear.
Humans
;
Dental Cementum/injuries*
;
Consensus
;
Diagnosis, Differential
;
Cone-Beam Computed Tomography
;
Tooth Fractures/therapy*
6.Biomechanical study and clinical application of two osteotomy guide methods in media open wedge high tibial osteotomy operation.
Chao QI ; Xiao-Ming LI ; Dong-Hui GUO ; Qiu-Ling SHI ; Yun-Chao ZHAO ; Jun DONG ; Zheng-Xin MENG ; Xing-Yue WANG
China Journal of Orthopaedics and Traumatology 2025;38(7):698-704
OBJECTIVE:
To explore the effectiveness and feasibility of two osteotomy guides in medial open wedge high tibial osteotomy (MOWHTO).
METHODS:
Clinical data of 103 patients who underwent routine MOWHTO surgery between January 2020 and December 2022 were collected for retrospective analysis. The patients were divided into two groups based on the method of osteotomy guide plate. The control group of 51 patients received traditional osteotomy guide plate technique, including 17 males and 34 females, aged from 48 to 68 years old with an average of(57.93±4.82) years old, with a disease duration ranged from 1 to 8 years with an average of (4.89±1.49) years. The observation group of 52 patients received personalized osteotomy guide plate technique, including 23 males and 29 females, aged from 48 to 69 with an average of (58.22±5.10) years, with a disease duration ranged from 1 to 9 years with an average of(5.10±1.55) years. The perioperative indicators, complications, and knee joint recovery rate were statistically analyzed for both groups, as well as the preoperative and postoperative coagulation function, fibrinogen (FIB), D-dimer (D-D), gait parameters (step frequency, step length, step speed), biomechanical indicators, weight bearing line (WBL), medial proximal tibial angle (MPTA), joint line conergence angle (JLCA), and anterior cruciate ligament (ACL) function (body width, tibial anterior displacement).
RESULTS:
All patients were followed up for 6 months. The intraoperative blood loss, operation time, and number of fluoroscopic views in the observation group were (358.58±93.76) ml, (84.42±8.17) min, and (2.00±0.44) times, respectively, which were all less than those in the control group (465.55±105.38) ml, (96.53±10.51) min, and (6.31±0.58) times (P<0.05). Three days after surgery, the FIB and D-D levels in the observation group were (4.21±0.48) g·L-1 and (204.47±35.59) μg·L-1, respectively, which were both lower than those in the control group (5.56±0.57) g·L-1 and (311.12±42.23) μg·L-1 (P<0.05). Three months after surgery, the step frequency, step length, and step speed in the observation group were (1.89±0.23) steps·s-1, (0.57±0.15) m, and (0.99±0.11) m·s-1, respectively, which were all higher than those in the control group (1.80±0.18) steps·s-1, (0.50±0.14) m, and (0.95±0.09) m·s-1 (P<0.05). Three months after surgery, the WBL and MPTA in the observation group were (45.53±4.41)% and (87.03±8.15)°, respectively, which were both higher than those in the control group (38.38±4.36)% and (83.68±8.50)°, and the JLCA was (2.36±0.24)°, which was lower than that in the control group (2.61±0.33)° (P<0.05). The ACL body width during internal fixation removal was (5.60±0.51) mm, which was greater than that in the control group (5.08±0.56) mm, and the tibial migration was (5.70±0.42) mm, which was less than that in the control group (6.33±0.48) mm (P<0.05). There was no significant difference in the incidence of complications between the two groups (P>0.05). Six months after surgery, there was no significant difference in the recovery rate of knee joint between the two groups (P>0.05).
CONCLUSION
The application of personalized osteotomy guide technique in MOWHTO can help improve knee biomechanics and ACL function, and has less effect on coagulation function and no increase in complications.
Humans
;
Male
;
Female
;
Osteotomy/methods*
;
Middle Aged
;
Tibia/physiopathology*
;
Aged
;
Biomechanical Phenomena
;
Retrospective Studies
;
Osteoarthritis, Knee/physiopathology*
7.Structural equation analysis of the incidence of shoulder WMSDs and individual and work-related factors
Shuang ZHOU ; Zhongxu WANG ; Ruijie LING ; Qing XU ; Huadong ZHANG ; Yimin LIU ; Gang LI ; Yan YIN ; Hua SHAO ; Jue LI ; Hengdong ZHANG ; Bing QIU ; Dayu WANG ; Qiang ZENG ; Yan YE ; Bin XIAO ; Hua ZOU ; Jianchao CHEN ; Dongxia LI ; Yongquan LIU ; Jixiang LIU ; Enfei JIANG ; Jun QI ; Liangying MEI ; Xianfeng ZHAO ; Mimi YANG ; Ning JIA
Chinese Journal of Industrial Hygiene and Occupational Diseases 2025;43(2):91-100
Objective:To investigate the incidence of shoulder work-related musculoskeletal disorders (WMSDs) among occupational population in China, and to explore their intrinsic association with personal and work-related factors.Methods:In April 2024, 73497 valid questionnaires of the Chinese version of the Musculoskeletal Disorders Electronic Questionnaire were retrospectively analyzed from June 2018 to December 2023 in 22 provinces and 29 key industries in China, and the general information, occurrence of WMSDs and related risk factors of key occupational populations in different regions in China were collected. By using Chi-square test and confirmatory factor analysis, the relationship between shoulder fatigue and pain in key occupational groups and individual factors, work type, work posture and work organization was discussed, and the internal relationship was analyzed based on structural equation model.Results:Higher incidence of shoulder fatigue and pain were associated with female, lack of physical exercise, uncomfortable working posture and neck leaning forward ( P<0.05). Structural equation model analysis showed that work type, work posture and work organization were strongly correlated ( r=0.58, 0.55). Work organization and work type were strongly correlated with shoulder fatigue ( r=0.65) and moderately correlated with shoulder fatigue ( r=0.21). Shoulder fatigue was moderately associated with shoulder pain ( r=0.40). Individual factors, work type, work posture and shoulder fatigue could directly affect shoulder pain ( OR=0.07, -0.09, 0.17 and 0.40), and work type and work posture could also indirectly affect shoulder pain through shoulder fatigue ( OR=0.08, 0.03). Work organization only indirectly affected shoulder pain through shoulder fatigue ( OR=0.26) . Conclusion:The main influencing factor of shoulder pain is shoulder fatigue, followed by work posture and individual factors. Structural equation model can better reflect the complex relationship between work type, work posture and work organization and shoulder WMSDs. Improving work posture and work organization may be an effective way to control the influence of shoulder fatigue on shoulder pain.
8.Structural equation analysis and modeling of fect and ankles WMSDs and its adverse ergonomic factors
Xi ZHANG ; Ning JIA ; Xin SUN ; Meibian ZHANG ; Qing XU ; Huadong ZHANG ; Ruijie LING ; Yimin LIU ; Gang LI ; Yan YIN ; Hua SHAO ; Hengdong ZHANG ; Yanmin QI ; Bing QIU ; Tiebing LIU ; Dayu WANG ; Qiang ZENG ; Yan YE ; Bin XIAO ; Hua ZOU ; Jianchao CHEN ; Dongxia LI ; Yongquan LIU ; Jixiang LIU ; Enfei JIANG ; Jun QI ; Liangying MEI ; Tianlai LI ; Mimi YANG ; Xinwei GUO ; Zhongxu WANG
Chinese Journal of Industrial Hygiene and Occupational Diseases 2025;43(2):101-109
Objective:To explore the structural equation model to explore the levels of work-related musculoskeletal disorders (WMSDs) and various risk factors in the feet and ankle of China's occupational population, providing scientific basis for for preventing WMSDs in feet and ankles.Methods:Data of 73497 national occupational epidemiological cases were selected from June 2018 to December 2023 used the Chinese version of the Electronic Questionnaire on Musculoskeletal Disorders. The adverse ergonomic factors and their source classification standard and confirmatory factor analysis were used to investigate foot and ankle WMSDs and their related risk factors (including individual factors, work organization, work posture, work type, fatigue, etc.) in key occupational groups in China, and structural equation model hypothesis, fitting, verification, and path and intermediary effect analysis were carried out. The model fit evaluation indexes included Chi-square specific degrees of freedom ( χ2/ df), gauge fit index (NFI), Tucker Lewis index (TLI), goodness of Fit index (GFI), adjusted Goodness of Fit index (AGFI) and approximate root mean square error (RMSEA) . Results:A total of 73497 occupational workers were surveyed, with local muscle fatigue and WMSDs incidence rates in the feet and ankles being 17.17% and 12.06%, respectively. The fitting index of the adjusted structural equation model basically meets the standard (GFI=1, AGFI=1, RMESA=0.042, NFI=0.716, TLI=0.663). The top three factors affecting feet and ankle WMSDs are feet and ankle muscle fatigue, work type, and work organization, with standardized path coefficients of 0.221, 0.105, and 0.095, respectively. The top two factors affecting feet and ankle muscle fatigue are work organization and work type, with standardized path coefficients of 0.548 and 0.383, respectively. Feet and ankle muscle fatigue, work type, work organization, and work posture have a direct effect on feet and ankle WMSDs, with effect values of 0.221, 0.105, 0.095, and 0.077, respectively. The organization and type of work can also have indirect effects through feet and ankle muscle fatigue, with effect values of 0.121 and 0.084, respectively.Conclusion:Feet and ankle muscle fatigue has a direct impact on WMSDs, and plays a mediating role between ankle and ankle WMSDs caused by work organization and work type. Feet and ankle muscle fatigue is an important pathway leading to feet and ankle WMSDs. It is recommended that employers and managers detect job fatigue early and take corresponding prevention and intervention measures, which can play a key role in preventing feet and ankle WMSDs.
9.Structural equation analysis and modeling of upper limb WMSDs and their adverse ergonomic factors
Siwu ZHONG ; Ning JIA ; Xin SUN ; Meibian ZHANG ; Qing XU ; Huadong ZHANG ; Ruijie LING ; Yimin LIU ; Gang LI ; Yan YIN ; Hua SHAO ; Jue LI ; Hengdong ZHANG ; Bing QIU ; Dayu WANG ; Qiang ZENG ; Rugang WANG ; Yan YE ; Bin XIAO ; Hua ZOU ; Jianchao CHEN ; Dongxia LI ; Yongquan LIU ; Qinghua SHI ; Jixiang LIU ; Enfei JIANG ; Jun QI ; Liangying MEI ; Xianfeng ZHAO ; Mimi YANG ; Xinwei GUO ; Zhi WANG ; Zhongxu WANG
Chinese Journal of Industrial Hygiene and Occupational Diseases 2025;43(4):254-263
Objective:To explore the structural relationship between WMSDs in the upper limbs and various risk factors in the occupational population in China, based on a large sample epidemiological survey and structural equation analysis, and to establish a structural equation model, so as to lay a foundation for the prevention and control of such diseases.Methods:The Chinese version of the Musculoskeletal Disorders Electronic Questionnaire was used to conduct a nationwide survey on the prevalence of WMSDs in the upper extremity. Six factors related to WMSDs in the upper extremity were extracted by the classification standard of adverse ergonomic factors and their source and confirmatory factor analysis, including work organization, work type, upper extremity work posture, individual factors, upper extremity fatigue and upper extremity WMSDs. The structural equation analysis was carried out and the structural equation model was established.Results:The incidence of WMSDs and fatigue in the upper limbs was 24.44% and 43.76%, respectively. The adjusted structural equation model fitting indicators were generally up to the standard (GFI=1.000, AGFI=1.000, RMSEA=0.043, NFI=0.808, TLI=0.784) . The four exogenous latent variables of work organization, work type, upper limb work posture and individual factors were correlated. There was a strong positive correlation between job type and upper limb work posture ( r=0.865) , a moderate positive correlation between work organization and job type and upper limb work posture ( r=0.570, 0.490) , and a weak negative correlation between individual factors and the other three exogenous latent variables. Upper limb work posture and individual factors had direct effects on upper limb WMSDs, and the effect coefficients were 0.10 and 0.06, respectively. Upper limb fatigue played a mediating role between work organization, work type, upper limb work posture and upper limb WMSDs. The effect coefficient was 0.46, and the composition ratios of indirect effects were 100.0%, 100.0%, and 38.3%, respectively. The direct path effect of upper limb work posture, individual factors and upper limb WMSDs was weaker than the mediating path through upper limb fatigue. Conclusion:When carrying out the prevention and control of upper limbWMSDs, it is necessary to comprehensively consider the pathogenesis path of upper limb muscle fatigue and upper limb WMSDs caused by work organization, work type, and upper limb work posture, so as to provide theoretical reference for improving the prevention and control level of such diseases.
10.Isolation,identification,and biological characterization of enterotoxigenic Escherichia coli from a South China tiger
Jing-ru XU ; Zhi-hao ZHU ; Yu-qi LI ; Si-si FAN ; Ya-li KANG ; Yu-bin ZHUO ; Ling-shan HUANG ; Shu-qi QIU ; XUE-YUXI ; Xiao-ping WU ; Yu-ting LIAO ; Wei-ye LIN ; Xiao-ziyi XIAO ; Xue-jin LI ; Teng-teng CHEN ; Xi-pan LIN ; Kai-xiong LIN ; Ke-wei FAN
Chinese Journal of Zoonoses 2025;41(6):567-573
This study was aimed at identifying the pathogenic bacteria responsible for the death of a young tiger at the Fujian Meihua Mountain South China Tiger Breeding Research Institute.Tissue samples from the lungs,liver,and intestines of the deceased tiger were collected,and the bacteria were cultured inasterile environment.The bacterial strains were characterized according to their morphological and molecular biological properties,including assessment of virulence genes and antibiotic resistance genes,mouse lethality tests,and antibiotic susceptibility evaluations.A predominant bacterial strain isolated from the liver of the deceased tiger was identified as enterotoxigenic Escherichia coli(ETEC)strain Tiger22513F.Phylogenetic analysis of the 16S rRNA gene revealed that the Tiger22513F strain exhibited close genetic similarity to the reference strain ETEC(MF919609.1),with 99.9%nucleotide similarity,and resided on the same evolutionary branch.The Tiger22513F strain contained 11 antibiotic resistance genes(tetA,sul1,sul3,cmlA,floR,blaTEM,blaSHV,blaCMY-2,qnrA,qnrS,and qnrD)along with five virulence genes(VT1,fyuA,tsh,iucD,and ST).Mouse lethality tests indicated significant pathogenicity toward mice,affecting primarily the lungs,liver,and intestines.Antibiotic susceptibility testing demonstrated that this strain exhibited resistance to various classes of beta-lactam antibiotics,as well as quinolones and aminoglycosides.This investigation successfully isolated a multi-drug resistant enterotoxigenic Escherichia coli strain with pronounced pathogenicity from the liver of a deceased tiger;thus providing valuable scientific insights for clinical diagnosis,as well as prevention and control measures,against ETEC infections in South China tigers.

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