Number of parity and the risk of gallbladder cancer: a systematic review and dose-response meta-analysis of observational studies.

BACKGROUND: Current epidemiological evidence suggests an association between parity and risk of gallbladder cancer (GBC), but studies have yielded inconsistent conclusions. OBJECTIVE: The purpose of this meta-analysis is to systematically analyze the effect of the number of parity on GBC risk. METHODS: We searched Web of Science, EMBASE, PubMed, China Biological Medicine Database from inception to the end of April 2015. Studies investigating parity and risk of GBC were included. A systematic review and a dose-response meta-analysis were performed to investigate the association between parity and GBC risk using odds ratios (OR) and 95 % confidence intervals (CI). RESULTS: Thirteen case-control studies were eligible for inclusion in this meta-analysis, including a total of 2,164 cases and 11,340 controls. A significant association was identified for the ever parity vs. nulliparous at 1.39 (95 % CI 1.15-1.68; Power = 0.73; I (2) =0.0 %; P = 0.90). Similarly, the summary estimate for high vs. low parity number was 1.86 (95 % CI 1.51-2.30; Power = 0.26; I (2) = 66.0 % P < 0.01). For the dose-response relationship, a non-linear association between the parity number and GBC risk was not observed (P non-linearity = 0.578), but a clear linear relationship was detected. The combined odds ratio of GBC for an increase in parity of one live birth was 1.12 (95 % CI 1.09-1.21; Power = 0.99; I (2) = 39.9 %; P = 0.139). Subgroup and sensitivity analyses showed similar associations. No publication bias was found in all results. Significant heterogeneity between subgroups was detected by meta-regression analyses. CONCLUSIONS: In females, higher parity may be associated with an increased risk of gallbladder cancer. In the future, high-quality cohort studies with larger sample sizes and randomized controlled trials are needed to fully scrutinize this association.

Characterization of pKPN945B, a novel transferable IncR plasmid from hypervirulent carbapenem-resistant Klebsiella pneumoniae, harboring blaIMP-4 and qnrS1.

Carbapenem-resistant Klebsiella pneumoniae producing metallo-ß-lactamase poses a major public health threat worldwide. Imipenemase often coexists with other resistance genes leading to the formation of multidrug-resistant bacteria. In this study, we describe the microbiological and genomic characteristics of the hypervirulent carbapenem-resistant K. pneumoniae ST20-K23 strain KPN945 harboring blaIMP-4 and qnrS1. The minimum inhibitory concentration of KPN945 against antimicrobials was determined by the broth microdilution method. The virulence of KPN945 was evaluated through string test, serum killing resistance, and Galleria mellonella larvae infection models. The transferability of pKPN945B was assessed using a conjugation test. The genome sequence characteristics of KPN945 were analyzed through whole genome sequencing, and a phylogenetic tree was constructed to evaluate the prevalence of imipenemase. Our findings showed that KPN945 was non-susceptible to ß-lactam antibiotics, highly resistant to serum killing, and highly lethal to G. mellonella larvae. The fusion plasmid pKPN945B carried by the isolate KPN945 belonged to the IncR incompatibility group and harbored multiple drug resistance genes such as blaIMP-4, blaCTX-M-14, qnrS1, and sul2. The most important point is that the IncR plasmid is a novel plasmid that arose by the accretion of parts from different plasmids, making it transferable and with a fitness cost. Globally, blaIMP-4 is the most prevalent imipenemase subtype, with the highest isolation rates in Asia, particularly China. The spread of blaIMP-4, especially the emergence of transferable plasmids, deserves our vigilance and prevention. Additionally, we should pay attention to the formation of hypervirulent K. pneumoniae mediated by non-virulent plasmids. IMPORTANCE: Up to now, IncR replicons carrying blaIMP-4 have not been reported, and the IncR plasmids described in previous studies have been found to be non-transferrable to other bacteria through conjugation. Moreover, there have been no extensive phylogenetic analyses of strains carrying blaIMP in the published papers. The lack of data in these studies is noteworthy because blaIMP appears in the novel transferable fusion plasmid IncR. Although the IncR plasmid has no tra operon, it can still be transferred to Escherichia coli EC600 or Klebsiella pneumoniae ATCC13883 (RIFR) without high fitness cost, but it only affects the MIC of imipenem. blaIMP integrates with other resistance mechanisms leading to the formation of multidrug-resistant strains. Notably, the high prevalence of blaIMP-4 in Asia and the presence of blaIMP-4 on novel transferable IncR plasmids suggest the urgent need to monitor the emergence of such plasmids and control their spread.

Carbapenem-Resistant Enterobacter cloacae Complex in Southwest China: Molecular Characteristics and Risk Factors Caused by NDM Producers.

Purpose: The isolation rate of carbapenem-resistant Enterobacter cloacae complex (CREC) is continuously increasing. The aims of this study were to investigate the molecular characteristics and risk factors associated with CREC infections. Methods: Bacterial species were identified using the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) (Bruker Daltonik GmbH, Bremen, Germany), and the hsp60 gene was utilized for further typing. Antimicrobial susceptibilities were assessed through the MicroScan WalkAway 96 Plus system (Siemens, Germany) and the microbroth dilution method. Antimicrobial resistance genes were screened through polymerase chain reaction (PCR), while the homologous relationship was assessed using multilocus sequence typing (MLST). Conjugation experiments were performed to verify whether the plasmid could be transferred. Additionally, logistic regression model was employed to analyze risk factors for CREC infections. Results: 32 strains of CREC bacteria were isolated during the study, yet only 20 were retained for preservation. While the isolates demonstrated resistance to the majority of antibiotics, they exhibited high sensitivity to polymyxin B and tigecycline. All isolates carried the blaNDM resistance gene, including 13 blaNDM-1 isolates and 7 blaNDM-5 isolates. MLST homology analysis revealed the presence of seven known ST types and one new ST type. Conjugation experiments confirmed that 13 isolates were capable of transferring the blaNDM resistance gene to Escherichia coli strain EC600. Single-factor analysis identified multiple primary risk factors for CREC infection, but multivariate analysis did not reveal independent risk factors. Conclusion: This study investigates the molecular characteristics and risk factors associated with CREC infections. The detection rate of CREC strains in our hospital is continuously rising and homology analysis suggested that strains might spread in our hospital, emphasizing the importance of implementing effective preventive measures to control the horizontal transmission of plasmid-mediated antimicrobial resistance genes.

Identification and characterization of a novel aminoglycoside O-nucleotidyltransferase ANT(6)-If from Paenibacillus thiaminolyticus PATH554.

Background: Paenibacillus thiaminolyticus, a species of genus Paenibacillus of the family Paenibacillaceae, exists widely in environments and habitats in various plants and worms, and occasionally causes human infections. This work aimed to characterize the function of a novel aminoglycoside O-nucleotidyltransferase resistance gene, designated ant(6)-If, from a P. thiaminolyticus strain PATH554. Methods: Molecular cloning, antimicrobial susceptibility testing, enzyme expression and purification, and kinetic analysis were used to validate the function of the novel gene. Whole-genome sequencing and comparative genomic analysis were performed to investigate the phylogenetic relationship of ANT(6)-If and other aminoglycoside O-nucleotidyltransferases, and the synteny of ant(6)-If related sequences. Results: The recombinant with the cloned ant(6)-If gene (pMD19-ant(6)-If/DH5α) demonstrated a 128-fold increase of minimum inhibitory concentration level against streptomycin, compared with the control strains (DH5α and pMD19/DH5α). The kinetic parameter kcat/Km of ANT(6)-If for streptomycin was 9.01 × 103 M-1·s-1. Among the function-characterized resistance genes, ANT(6)-If shared the highest amino acid sequence identity of 75.35% with AadK. The ant(6)-If gene was located within a relatively conserved genomic region in the chromosome. Conclusion: ant(6)-If conferred resistance to streptomycin. The study of a novel resistance gene in an unusual environmental bacterium in this work contributed to elucidating the resistance mechanisms in the microorganisms.

Molecular Mechanism of the ß-Lactamase Mediated ß-Lactam Antibiotic Resistance of Pseudomonas aeruginosa Isolated From a Chinese Teaching Hospital.

Pseudomonas aeruginosa can cause infections in the blood, lungs (pneumonia), or other parts of the body after surgery. To investigate the molecular characteristics of ß-lactam antibiotic resistance of P. aeruginosa isolated from a hospital population between 2015 and 2017, in this study, the antimicrobial susceptibility and the resistance gene profile of the bacteria were determined. The Pulsed-field gel electrophoresis (PFGE) was used to characterize the clonal relatedness and sequencing and comparative genomic analysis were performed to analyze the structure of the resistance gene-related sequences. As a result, of the 260 P. aeruginosa strains analyzed, the resistance rates for 6 ß-lactam antibiotics ranged from 4.6 to 9.6%. A total of 7 genotypes of 44 ß-lactamase genes were identified in 23 isolates (8.9%, 23/260). Four transconjugants from different donors carrying bla CARB-3 exhibited a phenotype of reduced susceptibility to piperacillin-tazobactam, ceftazidime, and cefepime, and 2 transconjugants harboring bla IMP-45 exhibited a phenotype of reduced susceptibility to carbapenems. bla CARB positive isolates (n = 12) presented six PFGE patterns, designated groups A to F. Two bla genes (bla IMP-45 and bla OXA-1) in PA1609 related to a class 1 integron (intI1-bla IMP-45- bla OXA-1-aac(6')-Ib7-catB3-qacE∆1-sul1) were encoded on a plasmid (pPA1609-475), while the bla CARB-3 gene of PA1616 also related to a class 1 integron was located on the chromosome. The results suggest that ß-lactam antibiotic resistance and clonal dissemination exist in this hospital population. It indicates the necessity for molecular surveillance in tracking ß-lactamase-producing strains and emphasizes the need for epidemiological monitoring.

Colistin Resistance and Molecular Characterization of the Genomes of mcr-1-Positive Escherichia coli Clinical Isolates.

Research on resistance against polymyxins induced by the mcr-1 gene is gaining interest. In this study, using agar dilution method, polymerase chain reaction, and comparative genomic analysis, we investigated the colistin resistance mechanism of clinical E. coli isolates. The minimum inhibitory concentration (MIC) analysis results revealed that of the 515 isolates tested, bacteria with significantly increased MIC levels against colistin were isolated in 2019. Approximately one-fifth (17.14% to 19.65%) of the isolates showed MIC values ≥1 mg/L against colistin in 2015, 2016, and 2017. However, in 2019, up to three-quarters (74.11%, 146/197) of the isolates showed MIC values ≥1 mg/L against colistin indicating an increase in colistin resistance. Six isolates (EC7518, EC4968, EC3769, EC16, EC117, EC195, 1.13%, 6/515) were found to carry the mcr-1 gene and a novel mcr-1 variant with Met2Ile mutation was identified in EC3769. All six strains showed higher MIC levels (MIC=4 mg/L) than any mcr-1-negative strains (MIC ≤ 2 mg/L). Whole-genome sequencing of the six mcr-1-positive isolates revealed that EC195 carried the highest number of resistance genes (n = 28), nearly a half more than those of the following EC117 (n = 19). Thus, EC195 showed a wider resistance spectrum and higher MIC levels against the antimicrobials tested than the other five isolates. Multi-locus sequence typing demonstrated that these mcr-1-positive strains belonged to six different sequence types. The six mcr-1 genes were located in three different incompatibility group plasmids (IncI2, IncHI2 and IncX4). The genetic context of mcr-1 was related to a sequence derived from Tn6330 (ISApl1-mcr-1-pap2-ISApl1). Investigations into the colistin resistance mechanism and characterization of the molecular background of the mcr genes may help trace the development and spread of colistin resistance in clinical settings.

Molecular characterization of florfenicol and oxazolidinone resistance in Enterococcus isolates from animals in China.

Florfenicol is widely used for the treatment of bacterial infections in domestic animals. The aim of this study was to analyze the molecular mechanisms of florfenicol and oxazolidinone resistance in Enterococcus isolates from anal feces of domestic animals. The minimum inhibitory concentration (MIC) levels were determined by the agar dilution method. Polymerase chain reaction (PCR) was performed to analyze the distribution of the resistance genes. Whole-genome sequencing and comparative plasmid analysis was conducted to analyze the resistance gene environment. A total of 351 non-duplicated enteric strains were obtained. Among these isolates, 22 Enterococcus isolates, including 19 Enterococcus. faecium and 3 Enterococcus. faecalis, were further studied. 31 florfenicol resistance genes (13 fexA, 3 fexB, 12 optrA, and 3 poxtA genes) were identified in 15 of the 19 E. faecium isolates, and no florfenicol or oxazolidinone resistance genes were identified in 3 E. faecalis isolates. Whole-genome sequencing of E. faecium P47, which had all four florfenicol and oxazolidinone resistance genes and high MIC levels for both florfenicol (256 mg/L) and linezolid (8 mg/L), revealed that it contained a chromosome and 3 plasmids (pP47-27, pP47-61, and pP47-180). The four florfenicol and oxazolidinone resistance genes were all related to the insertion sequences IS1216 and located on two smaller plasmids. The genes fexB and poxtA encoded in pP47-27, while fexA and optrA encoded in the conjugative plasmid pP47-61. Comparative analysis of homologous plasmids revealed that the sequences with high identities were plasmid sequences from various Enterococcus species except for the Tn6349 sequence from a Staphylococcus aureus chromosome (MH746818.1). The current study revealed that florfenicol and oxazolidinone resistance genes (fexA, fexB, poxtA, and optrA) were widely distributed in Enterococcus isolates from animal in China. The mobile genetic elements, including the insertion sequences and conjugative plasmid, played an important role in the horizontal transfer of florfenicol and oxazolidinone resistance.

Functional characterization of a novel aminoglycoside phosphotransferase, APH(9)-Ic, and its variant from Stenotrophomonas maltophilia.

Background: The intrinsic resistance mechanism plays an essential role in the bacterial resistance to a variety of the antimicrobials. The aim of this study is to find the chromosome-encoded novel antimicrobial resistance gene in the clinical isolate. Methods: The function of the predicted resistance gene was verified by gene cloning and antibiotic susceptibility test. Recombinant protein expression and enzyme kinetic studies were performed to explore the in vivo activity of the enzyme. Expression of the resistance gene exposed to antimicrobial was determined by RT-qPCR. Whole genome sequencing and bioinformatic analysis were applied to analyze the genetic context of the resistance gene. Results: The novel aminoglycoside (AG) resistance genes designated aph(9)-Ic and aph(9)-Ic1 confer resistance to spectinomycin, and a recombinant strain harboring aph(9)-Ic (pMD19-T-aph(9)-Ic/DH5α) showed a significantly increased minimum inhibitory concentration (MIC) level against spectinomycin compared with the control strains (DH5α and pMD19-T/DH5α). The result of the kinetic analysis of APH(9)-Ic was consistent with the MIC result for the recombinant pMD19-T-aph(9)-Ic/DH5α, showing the efficient catalytic activity for spectinomycin [kcat/Km ratio = (5.58 ± 0.31) × 104 M-1·s-1]. Whole-genome sequencing demonstrated that the aph(9)-Ic gene was located on the chromosome with a relatively conserved genetic environment, and no mobile genetic element was found in its surrounding region. Among all the function-characterized resistance genes, APH(9)-Ic shares the highest amino acid sequence identity of 33.75% with APH(9)-Ia. Conclusion: We characterized a novel AG resistance gene aph(9)-Ic and its variant aph(9)-Ic1 that mediated spectinomycin resistance from S. maltophilia. The identification of the novel AG resistance genes will assist us in elucidating the complexity of resistance mechanisms in microbial populations.

Characterization and identification of a novel chromosomal class C ß-lactamase, LAQ-1, and comparative genomic analysis of a multidrug resistance plasmid in Lelliottia amnigena P13.

Introduction: Lelliottia amnigena, a bacterium usually isolated from natural environments, may cause human infections and has been suggested to be naturally resistant to second- and third-generation cephalosporins. Methods: In this study, we determined the whole-genome sequence of an isolate, L. Amnigena P13, isolated from animal farm sewage. On the basis of genome sequence analysis, susceptibility testing, molecular cloning, and enzyme kinetic parameter analysis, we identified a novel chromosome-encoded AmpC ß-lactamase, LAQ-1. Results and Discussion: bla LAQ-1 is resistant to penicillin G, ampicillin, and several first- to fourth-generation cephalosporins, such as cefazolin, cefoxitin and cefepime. The MIC levels of some ß-lactams, such as cefoxitin, cefepime, aztreonam and cefazolin, for the recombinant clone (pUCP24-bla LAQ-1/DH5α) increased by approximately 4- to 64-fold compared with those of the control strain (pUCP24/DH5α). The kinetic properties of LAQ-1, with the highest catalytic activity observed toward piperacillin, were basically the same as those of typical class C ß-lactamases, and avibactam had a strong inhibitory effect on its hydrolytic activity. The genetic background of bla LAQ-1 was relatively conserved, and no mobile genetic element (MGE) was found around it. The plasmid pP13-67 of L. amnigena P13 harbored 12 resistance genes [qnrS1, aph(6)-Id, aadA2, sul1, sul2, bla TEM-1, qacEΔ1, dfrA12, tetA and floR] related to different mobile genetic elements within an ~22 kb multidrug resistance region. The multidrug resistance region shared the highest nucleotide sequence similarities with those of the chromosomes or plasmids of different bacterial species, indicating the possibility of horizontal transfer of these resistance genes among different bacterial species.

Characterization and Identification of a novel chromosome-encoded metallo-ß-lactamase WUS-1 in Myroides albus P34.

In this study, we identified and characterized a novel chromosomally-encoded class B metallo-ß-lactamase (MBL) gene designated bla WUS-1 in a carbapenem-resistant isolate Myroides albus P34 isolated from sewage discharged from an animal farm. Comparative analysis of the deduced amino acid sequence revealed that WUS-1 shares the highest amino acid similarities with the function-characterized MBLs MUS-1 (AAN63647.1; 70.73%) and TUS-1 (AAN63648.1; 70.32%). The recombinant carrying bla WUS-1 exhibited increased MICs levels against a number of ß-lactam antimicrobials such as carbenicillin, ampicillin and imipenem, and ß-lactamase inhibitors (clavulanic acid and tazobactam). The metallo-ß-lactamase WUS-1 could also hydrolyze these antimicrobials and the hydrolytic activities could be inhibited by EDTA. Genetic context analysis of bla WUS-1 revealed that no mobile genetic element was found in its surrounding region. The plasmid pMA84474 of Myroides albus P34 harbored 6 resistance genes (bla OXA-347, aadS, bla MYO-1, ereD, sul2 and ermF) within an approximately 17 kb multidrug resistance (MDR) region. These genes, however, were all related to mobile genetic elements.

AadA36, a novel chromosomal aminoglycoside nucleotidyltransferase from a clinical isolate of Providencia stuartii.

In this study, we characterized a novel chromosome-encoded aminoglycoside nucleotidyltransferase (ANT), AadA36, from the Providencia stuartii strain P14 isolated from the sputum specimen of a burn patient at a hospital in Wenzhou, China. Among the functionally characterized ANTs, AadA36 shared the highest amino acid sequence identity of 51.91% with AadA14. The whole genome of P. stuartii P14 consisted of one chromosome and two plasmids (designated pP14-166 and pP14-114). A total of 19 genes with ≥80% similarity with functionally characterized antimicrobial resistance genes (ARGs) were identified in the whole genome, including aminoglycosides [aac(2')-Ia, aph(6)-Id, aph(3″)-Ib, aac(6')-Ib, ant(3″)-IIa, aph(3')-Ia], ß-lactams (bla CMY-2 and bla OXA-10) and so on. Antimicrobial susceptibility testing showed that the aadA36 gene conferred specific resistance to spectinomycin and streptomycin, and the minimum inhibitory concentration (MIC) of these antimicrobials increased 128- and 64-fold compared with the control strain. The kinetic parameters of AadA36 were consistent with the MIC data of spectinomycin and streptomycin, with kcat /Km ratios of (1.07 ± 2.23) × 104 M-1 s-1 and (8.96 ± 1.01) × 103 M-1 s-1, respectively. The identification of a novel aminoglycoside resistance gene will help us further understand the complexity of the resistance mechanisms and provide deep insights into the dissemination of resistance genes in the microbial population.

Identification of a novel aminoglycoside O-nucleotidyltransferase AadA33 in Providencia vermicola.

A novel chromosome-encoded aminoglycoside O-nucleotidyltransferase AadA33 was identified in Providencia vermicola strain P13. The AadA33 shares the highest amino acid identity of 51.28% with the function characterized AadA31. Antibiotic susceptibility testing and enzyme kinetics analysis revealed that the function of AadA33 is to mediate spectinomycin and streptomycin resistance. The recombinant strain harboring aadA33 (pUCP20-aadA33/Escherichia coli DH5α) displayed >256- and 128-fold increases in the minimum inhibitory concentration levels to spectinomycin and streptomycin, respectively, compared with the control strains pUCP20/DH5α. Enzyme kinetic parameters manifested the substrate of AadA33 including spectinomycin and streptomycin, with k cat/K m of 3.28 × 104 (M-1 s-1) and 3.37 × 104 (M-1 s-1), respectively. Bioinformatics analysis revealed its structural mechanism of antimicrobial resistance, genetic context, and phylogenetic relationship with other aminoglycoside O-nucleotidyltransferases. This study of AadA33 contributed to understanding the function and resistance mechanism of aminoglycoside O-nucleotidyltransferase.

Identification and Characterization of a Novel Chromosomal Aminoglycoside 2'-N-Acetyltransferase, AAC(2')-If, From an Isolate of a Novel Providencia Species, Providencia wenzhouensis R33.

Multidrug-resistant bacteria from different sources have been steadily emerging, and an increasing number of resistance mechanisms are being uncovered. In this work, we characterized a novel resistance gene named aac(2')-If from an isolate of a novel Providencia species, Providencia wenzhouensis R33 (CCTCC AB 2021339). Susceptibility testing and enzyme kinetic parameter analysis were conducted to determine the function of the aminoglycoside 2'-N-acetyltransferase. Whole-genome sequencing and comparative genomic analysis were performed to elucidate the molecular characteristics of the genome and the genetic context of the resistance gene-related sequences. Among the functionally characterized resistance genes, AAC(2')-If shares the highest amino acid sequence identity of 70.79% with AAC(2')-Ia. AAC(2')-If confers resistance to several aminoglycoside antibiotics, showing the highest resistance activity against ribostamycin and neomycin. The recombinant strain harboring aac(2')-If (pUCP20-aac(2')-If/DH5α) showed 256- and 128-fold increases in the minimum inhibitory concentration (MIC) levels to ribostamycin and neomycin, respectively, compared with those of the control strains (DH5α and pUCP20/DH5α). The results of the kinetic analysis of AAC(2')-If were consistent with the MIC results of the cloned aac(2')-If with the highest catalytic efficiency for ribostamycin (k cat /K m ratio = [3.72 ± 0.52] × 104 M-1 ⋅s-1). Whole-genome sequencing demonstrated that the aac(2')-If gene was located on the chromosome with a relatively unique genetic environment. Identification of a novel aminoglycoside resistance gene in a strain of a novel Providencia species will help us find ways to elucidate the complexity of resistance mechanisms in the microbial population.

Characterization of a Novel Chromosome-Encoded AmpC ß-Lactamase Gene, bla PRC-1, in an Isolate of a Newly Classified Pseudomonas Species, Pseudomonas wenzhouensis A20, From Animal Farm Sewage.

In this work, we characterized a novel chromosome-encoded AmpC ß-lactamase gene, bla PRC-1, in an isolate of a newly classified Pseudomonas species designated Pseudomonas wenzhouensis A20, which was isolated from sewage discharged from an animal farm in Wenzhou, China. Susceptibility testing, molecular cloning, and enzyme kinetic parameter analysis were performed to determine the function and enzymatic properties of the ß-lactamase. Sequencing and comparative genomic analysis were conducted to clarify the phylogenetic relationship and genetic context of the bla PRC-1 gene. PRC-1 is a 379-amino acid AmpC ß-lactamase with a molecular weight of 41.48 kDa and a predicted pI of 6.44, sharing the highest amino acid identity (57.7%) with the functionally characterized AmpC ß-lactamase PDC-211 (ARX71249). bla PRC-1 confers resistance to many ß-lactam antibiotics, including penicillins (penicillin G, amoxicillin, and amoxicillin-clavulanic acid) and cephalosporins (cefazolin, ceftriaxone, and cefotaxime). The kinetic properties of PRC-1 were compatible with those of a typical class C ß-lactamase showing hydrolytic activities against ß-lactam antibiotics, and the hydrolytic activity was strongly inhibited by avibactam. The genetic context of bla PRC-1 was relatively conserved, and no mobile genetic element was predicted in its surrounding region. Identification of a novel ß-lactamase gene in an unusual environmental bacterium reveals that there might be numerous unknown resistance mechanisms in bacterial populations, which may pose potential risks to human health due to universal horizontal gene transfer between microorganisms. It is therefore of great value to carry out extensive research on the mechanism of antibiotic resistance.

Combination of serum gamma-glutamyltransferase and alkaline phosphatase in predicting the diagnosis of asymptomatic choledocholithiasis secondary to cholecystolithiasis.

BACKGROUND: Gamma-glutamyltransferase (GGT) is one of the most important laboratory tests for the evaluation of liver damage. Through a long-term clinical observation of patients with secondary asymptomatic choledocholithiasis, we found that most patients had abnormal GGT serum levels. AIM: To investigate the combination of serum GGT and alkaline phosphatase (ALP) in predicting the diagnosis of asymptomatic choledocholithiasis secondary to cholecystolithiasis. METHODS: In this retrospective cohort study, the clinical data of 829 patients with cholecystolithiasis admitted to the Third Affiliated Hospital of Zunyi Medical College from August 2014 to August 2017 were collected. Among these patients, 151 patients had secondary asymptomatic choledocholithiasis and served as the observation group, and the remaining 678 cholecystolithiasis patients served as the control group. Serum liver function indexes were detected in both groups, and the receiver operating characteristic (commonly known as ROC) curves were constructed for markers showing statistical significances. The cutoff value, sensitivity, and specificity of each marker were calculated according to the ROC curves. RESULTS: The overall incidence of asymptomatic choledocholithiasis secondary to cholecystolithiasis was 18.2%. The results of liver function indexes including serum aspartate aminotransferase, alanine aminotransferase, direct bilirubin and total bilirubin levels showed no significant differences between the two groups (P > 0.05). However, the serum GGT and ALP levels were significantly higher in the observation group than in the control group (P < 0.05). The ROC curve analysis showed that the area under the curve was 0.881 (95%CI: 0.830-0.932), 0.647 (95%CI: 0.583-0.711) and 0.923 (95%CI: 0.892-0.953) for GGT, ALP, and GGT + ALP, respectively. The corresponding cut-off values of GGT and ALP were 95.5 U/L and 151.5 U/L, sensitivity were 90.8% and 65.1%, and specificity were 83.6% and 59.8%, respectively. The sensitivity and specificity of GGT + ALP were 93.5% and 85.1%, respectively. CONCLUSION: An abnormally elevated serum GGT level has an important value in the diagnosis of asymptomatic choledocholithiasis secondary to cholecystolithiasis. The combination of serum GGT and ALP has better diagnostic performance. As a convenient, rapid and inexpensive test, it should be applied in secondary asymptomatic choledocholithiasis routine screening.

Diagnostic value of elevated serum carbohydrate antigen 199 level in acute cholangitis secondary to choledocholithiasis.

AIM: To investigate the diagnostic value of abnormal serum carbohydrate antigen 199 (CA199) level in acute cholangitis secondary to choledocholithiasis. METHODS: In this retrospective cohort study, the clinical data of 727 patients with choledocholithiasis admitted to the Third Affiliated Hospital of Zunyi Medical College from June 2011 to June 2017 were collected. Among these patients, 258 patients had secondary acute cholangitis and served as observation group, and the remaining 569 choledocholithiasis patients served as the control group. Serum liver function indexes and tumor markers were detected in both groups, and the receiver operating characteristic (ROC) curves were constructed for markers showing statistical significances. The cutoff value, sensitivity, and specificity of each marker were calculated according to the ROC curves. RESULTS: The results of liver function tests showed no significant differences between the two groups (P > 0.05). Tumor markers including serum CA125, CA153, carcinoembryonic antigen, and alpha fetoprotein levels were also not significantly different (P > 0.05); however, the serum CA199 level was significantly higher in the observation group than in the control group (P < 0.05). The ROC curve analysis showed that the area under the curve was 0.885 (95%CI: 0.841-0.929) for CA199, and the cutoff value of 52.5 kU/L had the highest diagnostic accuracy, with a sensitivity of 86.8% and a specificity of 81.6%. CONCLUSION: Abnormally elevated serum CA199 level has an important value in the diagnosis of acute cholangitis secondary to choledocholithiasis. It may be a specific inflammatory marker for acute cholangitis.

Mitochondrial DNA damage and its effect on mitochondrial function in rats with obstructive jaundice.

This study investigated mitochondrial DNA (mtDNA) damage in rats with obstructive jaundice (OJ) and to explore its effect on mitochondrial and hepatic function. Forty-eight male Wistar rats were randomly divided into two groups: sham-operated (Sham) and bile duct ligation (BDL). Blood and tissue samples were collected from the two groups on days 1, 4, 7 and 14 following surgery. Hepatic and mitochondrial function were measured. Long and accurate PCR, restriction enzyme digestion and gene sequencing were used to analyze the locations of mtDNA deletions. In addition, quantitative fluorescent PCR was used to measure the relative amounts of total DNA in hepatocytes and mtDNA deletions. Results showed that the hepatic and mitochondrial function was compromised in the BDL group compared to the Sham group. Notably, a novel 11,194-bp mtDNA deletion (nucleotide positions 4101-15294) and fewer mtDNA copies were found compared to the Sham group. With prolonged ligation time, there was a decrease in the copy number, while the ratio of mtDNA deletions to total mtDNA levels increased in the BDL group. These changes were consistent with damage to hepatic and mitochondrial function. A novel 11,194-bp mtDNA deletion and fewer mtDNA copies were detected in hepatocytes of rats with OJ. The mtDNA deletions may therefore be an important factor leading to mitochondrial and hepatic dysfunction.