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Xiaohong Xu,1,* Rongping Zhu,1,* Siyan Lian,1 Hui Zhang,2 Xin Chen,2 Lingfang Fan,1 Peisong Chen,2 Yingping Cao1 1Department of Clinical Laboratory, Fujian Medical University Union Hospital, Fuzhou, Fujian, People’s Republic of China; 2Medical Technology and Engineering, Fujian Medical University, Fuzhou, Fujian, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yingping Cao, Department of Clinical Laboratory, Fujian Medical University Union Hospital, Fuzhou, Fujian, People’s Republic of China, Tel +86-133-6591-0806, Email caoyingping@aliyun.comBackground: The emergence of polymyxin B resistance among carbapenem-resistant Klebsiella pneumoniae (CRKP) causes clinical treatment to be more difficult. We aimed to investigate the risk factors and resistance mechanisms in the polymyxin resistant CRKP (PR-CRKP) strains.Methods: From January 2021 to January 2022, 239 CRKP strains were selected, all of which were analyzed using antimicrobial susceptibility testing and clinical data. Polymerase chain reaction (PCR) was performed for the detection of resistance genes. RT-qPCR was used to quantify transcriptional levels of polymyxin resistance genes. Risk factors for polymyxin B resistant isolates were identified by logistic regression analysis.Results: The resistance rate of polymyxin B was 5.02%. In all CRKP strains, 41.84% came from the ICU. The percentage of carbapenemase producing strains was 93.72%. The main carbapenem resistance gene was blaKPC (90.79%). In the 12 strains of PR-CRKP screened, pmrB and pmrK were overexpressed in all samples which were linked with polymyxin B resistance. Multivariate analysis showed that coronary heart disease may be an independent risk factor predisposing patients to polymyxin B resistance.Conclusion: We determine the multifaceted mechanism and risk factors of polymyxin B resistance in CRKP. Polymyxin resistance is a complex and changing problem, and more research is required.Keywords: polymyxin B resistance, carbapenem-resistantKlebsiella pneumoniae, risk factors, mechanism

Bin Zhu,1 Junrong Zhang,2 Qingzhu Zheng,1 Binhua Dong,3 Meihua Wang,1 Jin Liu,1 Yingping Cao1 1Department of Clinical Laboratory, Fujian Medical University Union Hospital, Fuzhou, 350001, People’s Republic of China; 2Department of Emergency Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, People’s Republic of China; 3Laboratory of Gynecologic Oncology, Fujian Provincial Maternity and Children’s Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, People’s Republic of ChinaCorrespondence: Yingping CaoDepartment of Clinical Laboratory, Fujian Medical University Union Hospital, No. 29, Xinquan Road, Fuzhou City, Fujian Province, People’s Republic of ChinaEmail caoyingping918@sina.comPurpose: The aim of our study was to identify the diagnostic ability of free fatty acids (FFAs) in younger colorectal cancer (CRC) patients by comparing carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9).Methods: Patients screened for CRC at Fujian Medical University Union Hospital from January 2011 to December 2014 were recruited. Patients pathologically diagnosed with CRC or colorectal adenoma (CA) and healthy control participants were included. The enzyme endpoint method was applied to measure FFA levels. Receiver operating characteristic (ROC) curve analysis was performed to further evaluate the diagnostic ability of FFAs.Results: FFA levels in late-stage patients (tumour-node-metastasis (TNM) stages III–IV) were higher than those in early-stage patients (TNM stages I–II) (P=0.02). The FFA levels in CRC patients were higher than those in controls of all ages, those younger than 50 years, males and females (P< 0.001), and this difference was larger for patients younger than 50 years and females than for the all ages group. There was no significant difference in the FFA level between CA patients and healthy participants (P=0.53). The area under the curve (AUC) values of FFA, CEA, CA19-9, FFA+CEA, FFA+CA19-9 and FFA+CEA+CA19-9 distinguished CRC patients from controls at all ages, with values of 0.604, 0.731, 0.640, 0.754, 0.678 and 0.758, respectively; however, in the younger CRC patients (age≤ 50), the AUC values were 0.701, 0.735, 0.669, 0.798, 0.749, and 0.801. The AUC in female patients younger than 50 years was larger than that in males (0.769 vs 0.660), and this value was greater than the value for CEA in males (0.739) and females (0.729).Conclusion: The FFA level not only can complement the predictive ability of the CEA and CA19-9 levels but also has a superior predictive ability in female and younger patients with CRC. FFA levels may have a potential role in triage screening of early CRC.Keywords: free fatty acid, colorectal cancer, colorectal adenoma, sex, younger patients