Why consumers have impulsive purchase behavior in live streaming: the role of the streamer.

To explore the influencing factors of consumers' impulsive purchase behavior in live streaming, based on the Stimulus-Organism-Response framework, we construct the model of how streamers influence consumers' impulsive purchase behavior by consulting literature. Collected data by means of a questionnaire, and made an empirical study by using the structural equation model to explore the mechanism of streamer affecting consumers' impulsive purchase behavior. The results show that streamer characteristics (personal charisma, professionalism) and streamer performance (interactivity, entertainment) affect consumers' impulsive purchase behavior by affecting consumers' trust and flow experience. The empirical results have important theoretical and practical significance.

Differences in Contents and Formation Methods of Clinical Questions in Chinese and Korean Clinical Practice Guidelines of Acupuncture-Moxibustion: Scoping Review.

OBJECTIVE: To analyze the differences in the needs of users and the value orientation of clinical practice guidelines (CPGs) by comparing the contents and formation methods of clinical questions in Chinese and Korean CPGs of acupuncture-moxibustion (Acup-Mox). METHODS: The full text of CPGs was systematically searched from the official websites of Chinese and Korean traditional medicine societies and Acup-Mox associations, with the topic "Acup-Mox for treating diseases" and the retrieval time up to September 28, 2022. Two researchers screened the CPGs independently, and extracted the guidelines' topics, content, quantity and formation methods of clinical questions. The quantitative data were collected by counting the frequency, and the qualitative data were classified and described by thematic analysis. RESULTS: A total of 29 guidelines were included in this study, including 20 Chinese guidelines (305 questions) and 9 Korean guidelines (223 questions). The differences lie in the aspects of content and diversity, and formation method. As for content and diversity, Chinese guidelines focused mainly on the questions related to treatment such as the operation of specific intervention (86, 28.2%), efficacy of intervention (78, 25.6%), and also involving questions in diagnosis, prevention, and prognosis. While the clinical questions in Korean guidelines were concentrated to efficacy of intervention (218, 97.8%). As for formation method, in Chinese guidelines, questions were usually collected directly from clinicians, and then determined and optimized by experts. In Korean guidelines, frequently used clinical Acup-Mox interventions would be screened first. Then the expert group would set up corresponding intervention control measures so as to form clinical questions related to treatment efficacy. CONCLUSIONS: The differences reflect the different needs of clinical practitioners, and the different aims or concepts in developing Acup-Mox guidelines between China and South Korea. Chinese guidelines emphasized promoting operation protocols and techniques of Acup-Mox for practical use, while Korean guidelines emphasized promoting the frequently used clinical intervention therapies. It is speculated that the guidelines from these two countries would play different roles in guiding clinical operation and supporting medical decision. In terms of formation methods of clinical questions, it is suggested to attach importance to optimizing process in formatting clinical questions to improve the clinical applicability of CPGs of Acup-Mox.

Effect of administration of low-dose irbesartan and hydrochlorothiazide combined with levamlodipine at different times on the circadian rhythm of blood pressure and the levels of MMPs and TIMPs in non-dipper patients with grade 1 and 2 hypertension.

This study aimed to probe the effects of low-dose irbesartan and hydrochlorothiazide in combination with levamlodipine at different times on the circadian rhythm of blood pressure, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) levels in patients with non-dipper hypertension (NDH). In this prospective randomized controlled trial, 124 patients with NDH who visited our hospital between August 2018 and July 2021 were enrolled and divided into morning (62 patients) and night (62 patients) medication groups according to the random number table method. All patients received low-dose irbesartan and hydrochlorothiazide combined with levamlodipine, with the morning medication group taking the medication between 7:00 and 10:00 and the night medication group taking the medication between 19:00 and 22:00 for 24 weeks. The effect of antihypertensive medication in both groups was measured, and changes in ambulatory blood pressure, blood pressure circadian rhythm, left ventricular structure, vascular endothelial function, MMPs, and TIMPs levels were observed before treatment initiation and after 24 weeks of treatment in both groups. The percentage of the dipper type was higher in the night medication group than in the morning medication group, while the percentage of the non-dipper type was lower in the morning medication group (p < .05). Low-dose irbesartan and hydrochlorothiazide combined with levamlodipine at different times can effectively treat NDH, but bedtime dosing is more beneficial in reducing nocturnal blood pressure, reversing NDH, improving the circadian rhythm of blood pressure, left ventricular structure, regulating vascular endothelial function, increasing MMPs levels, and reducing TIMP levels.

Discussion on Collection of Clinical Questions in International Clinical Practice Guidelines of Acupuncture-Moxibustion.

The clinical questions of acupuncture-moxibustion (Acup-Mox) guidelines are complicated, including not only the curative effect of Acup-Mox intervention measures, but also the operational elements of Acup-Mox. This paper aimed to put forward the idea and process of collecting clinical questions in developing international acupuncture clinical practice guidelines. The experience was collected and the idea of collecting clinical questions of Acup-Mox was formed through expert consultation and discussion in combination with expert opinions. Based on the characteristics of Acup-Mox discipline. This paper put forward the thinking of collecting elements of clinical questions following the intervention-population-outcome-control (I-P-O-C) inquiry process, according to the discipline of Acup-Mox. It was emphasized that in the process of collecting clinical questions, "treatable population" and "alleviable outcome indicators" for a specific Acup-Mox intervention with certain therapeutic effect should be focused on, so as to highlight the pertinence of clinical questions of Acup-Mox guidelines in terms of population and outcome elements.

[Analysis and thought on reaching the consensus during the development of acupuncture and moxibustion clinical practice guidelines in China].

Based on the 28 Chinese clinical practice guidelines of acupuncture and moxibustion, this study summarized and analyzed the contents related to reaching consensus during the development process. The results indicated that all the 28 guidelines reported they have used consensus in the "recommendations" section, and provided details on consensus personnel, consensus methods, consensus process and consensus materials. However, it was found that the reporting of consensus was in need of further improvement. The limitations included unclear definition and responsibilities of "expert group", obscure concept between "consensus meeting" and "expert discussion", non-rigorous process of reaching consensus when generating recommendations and lacking of detailed reporting of the consensus reaching process. As such, we suggested that future researchers should conduct researches to further standardized the consensus process when developing acupuncture and moxibustion clinical practice guidelines, so as to improve the quality and clinical applicability of guidelines．.

[Investigation and analysis on the current situation of clinical practice guidelines for acupuncture and moxibustion at home and abroad].

To provide directional suggestions for the establishment of international clinical practice guidelines for acupuncture and moxibustion by investigating the current situation of clinical practice guidelines for acupuncture and moxibustion at home and abroad. The clinical practice guidelines were obtained by questionnaire survey, database retrieval and experts consulting. The guidelines were read carefully, and the content was analyzed. A total of 27 acupuncture-moxibustion clinical practice guidelines were retrieved, of which most of the guidelines came from China. The definition and scope of "acupuncture and moxibustion "vary according to different guidelines; and the focus of the content and the method of establishing the guidelines are quite different, so it is very necessary to unify the formulation methods of acupuncture-moxibustion clinical practice guidelines. Chinese clinical practice guidelines for acupuncture and moxibustion were characterized by taking the ancient literature as the evidence. Excavating the value of ancient literature and clinical experience of acupuncture-moxibustion experts are the key points and difficulties in the developing of clinical practice guidelines of acupuncture and moxibustion in the future.

[Consideration on existing problems in development of clinical practice guidelines for acupuncture and moxibustion in China].

To sort out the existing problems within the published 35 evidence-based acupuncture-moxibustion clinical practice guidelines (group standards) in Chinese: the development methods and the development process are not clear and strict enough; the evidence evaluation system fails to fully reflect the characteristics of acupuncture and moxibustion. Therefore, Norms for Formulation and Evaluation of the Guidelines on Clinical Practice of Acupuncture-Moxibustion, should require the guideline developers to consider the characteristics of acupuncture discipline, evaluate modern literature evidence comprehensively, and integrate ancient literature and medical experts' experience, to form proper recommendations for clinical practice. Specific requirements should be made simultaneously in the development process to make it clearer and stricter.

Liver paraoxonase 3 expression and the effect of liraglutide treatment in a rat model of diabetes.

BACKGROUND: This study investigated liver expression of paraoxonase 3 (PON3), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), and nuclear factor (NF)-κB in a rat model of type-2 diabetes mellitus (T2DM), and assessed the effect of liraglutide treatment. OBJECTIVES: To investigate liver PON3 expression in rats withT2DM assess its role in disease pathogenesis, and determine the effect of liraglutide on its expression. MATERIAL AND METHODS: Type 2 diabetes mellitus was induced in 3 groups of rats: positive control group (PC; no treatment), and low-dose (LL; 100 µg/kg) and high-dose (HL; 200 µg/kg) liraglutide groups. Healthy rats served as a normal control (NC) group. Protein and mRNA expression were measured with western blot and reverse-transcriptase polymerase chain reaction (RT-PCR), respectively. RESULTS: After liraglutide treatment, fasting plasma glucose (FPG), homeostasis model assessment-insulin resistance (HOMA-IR), fasting insulin (FINS), malondialdehyde (MDA), and interleukin 6 (IL-6) levels were lower in HL rats compared with LL ones (p < 0.05). Compared to NC rats, FPG, FINS, HOMA-IR, low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and IL-6 levels were the lowest in HL rats, followed by LL and PC ones (p < 0.05). Body weight (BW) was lower in LL and HL groups than in NC and PC (p < 0.05). The liver expression of PON3, PI3K and Akt were the highest in HL rats, followed by LL and PC (p < 0.05). The NF-κB expression was the lowest in HL rats, followed by LL and PC (p < 0.05). The PON3 expression was decreased in the diabetic rat liver. CONCLUSIONS: Liraglutide can increase PI3K, Akt and PON3 expression, and decrease NF-κB expression. The effect of liraglutide on improving insulin resistance and abnormal glucolipid metabolism in T2DM rats may be associated with increased liver PON3 expression.

Difference in biofilm formation between carbapenem-resistant and carbapenem-sensitive Klebsiella pneumoniae based on analysis of mrkH distribution.

OBJECT: To analyze the difference in biofilm formation between carbapenem-resistant and carbapenem-sensitive Klebsiella pneumoniae based on analysis of mrkH distribution and to further explore the function of mrkH for biofilm formation from the perspective of gene regulation. METHODS: 40 imipenem-resistant strains and 40 imipenem-sensitive strains were selected to conduct experiments. Carbapenem (imipenem) susceptibility test was performed by the agar-dilution method. blaKPC resistance gene, type 3 fimbriae-related coding genes (mrkA and mrkD) and regulation gene (mrkH) were screened by PCR. Biofilm formation assay was performed using crystal violet staining method in MHB. The relative expression of genes that critically involved in biofilm formation (mrkA, luxS, pgaA) and carbapenem resistance (ompk35, ompk36, acrB) were measured by quantitative real-time PCR (qRT-PCR). Furthermore, the mrkH cassette was cloned into pGEM-T Easy plasmid to yield pGEM:pmrkH and expressed in Escherichia coli DH5α and K. pneumoniae FK1911, and the biofilm formation assay after transformation was further tested. RESULTS: The MICs of imipenem were all more than 16 µg/mL in 40 imipenem-resistant strains and ranged from 0.125 µg/mL to 0.5 µg/mL in 40 imipenem-sensitive strains. Moreover, the blaKPC was identified in the 40 imipenem-resistant K. pneumoniae strains. All 80 K. pneumoniae strains were found to carry mrkA and mrkD genes. Interestingly, the mrkH gene was detected in 43 strains, of which 32 were carbapenem-sensitive strains. The biofilm formation capacity of strains carried mrkH cassette was significantly higher than other 37 strains in MHB media. The relative expression of mrkA in K. pneumoniae carrying mrkH gene was significantly up-regulated. Importantly, the biofilm formation ability of FK1911-pGEM:pmrkH strain was more higher than the strain of FK1911 in MHB medium. CONCLUSIONS: Our data demonstrated that MrkH played a crucial role in the regulation of biofilm formation by K. pneumoniae. In contrast to carbapenem-sensitive K. pneumoniae, carbapenem-resistant K. pneumoniae was less likely to have strong biofilm-forming capacity because it does not carry the mrkH gene.

Emergence of a multidrug-resistant ST 27 Escherichia coli co-harboring blaNDM-1, mcr-1, and fosA3 from a patient in China.

In this study, we report a clinical isolate of a carbapenem-, colistin-, and fosfomycin-resistant Escherichia coli isolate DC-3737 co-harboring blaNDM-1, mcr-1, and fosA3 from an inpatient in China. Antimicrobial susceptibility testing, polymerase chain reaction, multi-locus sequence typing, conjugation experiment, and Southern blot hybridization were performed on E. coli DC-3737 isolated from the wound. Plasmid analysis is presented and the locations of blaNDM-1, mcr-1, fosA3, and other resistance genes were identified as well. E. coli DC-3737 was resistant to ampicillin, ceftriaxone, ceftazidime, ciprofloxacin, levofloxacin, gentamicin, tobramycin, trimethoprim-sulfamethoxazole, imipenem, meropenem, ertapenem, fosfomycin and colistin, and with intermediate susceptibility to amikacin. It was typed as sequence type 27. The isolate possessed blaNDM-1, mcr-1, fosA3, blaCTX-M-9, blaTEM-1, aac (6')-Ib-cr and sul1 simultaneously. In addition, the mutations in quinolone resistance-determinant regions (QRDRs) such as Ser83Leu and Asp87Asn in gyrA, and Ser80Ile in parC were detected. Conjugation assays revealed that blaNDM-1, fosA3, sul1, mcr-1, and blaCTX-M-9 genes could successfully transfer their resistance phenotype to E. coli strain J53. Plasmid analysis and Southern hybridization showed that DC-3737 possessed Z-type self-transmissible plasmid bearing blaNDM-1, fosA3, and sul1. Moreover, mcr-1, blaCTX-M-9, and blaTEM-1 were located on a ~60-kb IncFIB type self-transmissible plasmid. This is the first report of blaNDM-1, mcr-1 and fosA3 co-harboring in E. coli in China. Moreover, it is also the first description of the co-harboring of blaNDM and fosA3 in a single Z plasmid in Enterobacteriaceae species. The identification of E. coli DC-3737 co-harboring blaNDM-1, mcr-1, and fosA3 in this study highlights the need to increase epidemiologic surveillance and the need for new classes of antibiotics to address multidrug-resistant bacteria.

Effects of iron on the growth, biofilm formation and virulence of Klebsiella pneumoniae causing liver abscess.

BACKGROUND: Klebsiella pneumoniae is considered the most clinically relevant species of Enterobacteriaceae, known to cause severe infections including liver abscesses. To the best of our knowledge, a large proportion of iron in the human body is accumulated and stored in the liver. We hypothesize that increased iron availability is an important factor driving liver abscess formation and we therefore aim to understand the effects of iron on K. pneumoniae causing liver abscesses. RESULTS: All tested K. pneumoniae clinical isolates, including those isolated from liver abscesses and other abdominal invasive infection sites, grew optimally when cultured in LB broth supplemented with 50 µM iron and exhibited the strongest biofilm formation ability under those conditions. Decreased growth and biofilm formation ability were observed in all tested strains when cultured with an iron chelator (P < 0.05). The infection model of G. mellonella larvae indicated the virulence of liver abscess-causing K. pneumoniae (2/3) cultured in LB broth with additional iron was significantly higher than those under iron-restricted conditions (P < 0.05). The relative expression levels of the four siderophore genes (iucB, iroB, irp1, entB) in K. pneumoniae strains isolated from liver abscesses cultured with additional iron were lower than those under iron-restricted conditions (P < 0.05). CONCLUSIONS: It is suggested by our research that iron in the environment can promote growth, biofilm formation and enhance virulence of K. pneumoniae causing liver abscesses. A lower expression of siderophore genes correlates with increased virulence of liver abscess-causing K. pneumoniae. Further deeper evaluation of these phenomena is warranted.

The new perspective of old antibiotic: In vitro antibacterial activity of TMP-SMZ against Klebsiella pneumoniae.

BACKGROUND/PURPOSE: Trimethoprim-sulfamethoxazole (TMP-SMZ) is broadly administered to treat multiple infections, and the paucity of effective treatment alternatives for infections caused by Klebsiella pneumoniae has led to a renewed interest in TMP-SMZ. The aim of this study is to evaluate the antibacterial efficacy of TMP-SMZ against K. pneumoniae. METHODS: The resistance genes of K. pneumoniae clinical isolates were investigated by PCR, followed by conjugation experiments and multilocus sequence typing. RESULTS: The resistance rate of K. pneumoniae to TMP-SMZ decreased over the collection period from 26.7% (88/330) to 16.9% (56/332). The high carrying rates (173/175, 98.9%) of resistance determinants (sul genes or dfr genes) were the main mechanisms of TMP-SMZ resistance isolates, with sul1 (142/175, 81.1%) and dfrA1 (119/175, 68.0%). Only class 1 integron was detected, the prevalence of which in TMP-SMZ resistant K. pneumoniae was 63.4% (111/175). CONCLUSION: These results provided insights into the antimicrobial efficacy of TMP-SMZ against K. pneumoniae, also illustrating the wide distribution of SMZ and TMP resistance genes among resistant K. pneumoniae. Simultaneously, the present study highlights the significance of reasonable administration and effective continued monitoring.

Zebrafish and Galleria mellonella: Models to Identify the Subsequent Infection and Evaluate the Immunological Differences in Different Klebsiella pneumoniae Intestinal Colonization Strains.

The intestine is the main reservoir of bacterial pathogens in most organisms. Klebsiella pneumoniae is an important opportunistic pathogen associated with nosocomial bacterial infections. Intestinal colonization with K. pneumoniae has been shown to be associated with an increased risk of subsequent infections. However, not all K. pneumoniae strains in the intestine cause further infection, and the distinction of the difference among strains that cause infection after colonization and the ones causing only asymptomatic colonization is unclear. In this study, we report a case of a hospitalized patient from the ICU. We screened out two intestine colonization strains (FK4111, FK4758) to analyze the subsequent infection conditions. We set up infection models of zebrafish and Galleria mellonella to establish the differences in the potential for causing subsequent infection and the immunological specificities after K. pneumoniae intestine colonization. Sudan Black B and neutral red staining results indicated that FK4758 was more responsive to neutrophil recruitment and phagocytosis of macrophages than FK4111. The results of the assessment of the organ bacterial load revealed that FK4111 and FK4758 both had the highest bacterial loads in the zebrafish intestine compared to those in other organs. However, in the zebrafish spleen, liver, and heart, the FK4758 load was significantly higher than that of FK4111. The ST37 strain FK4111, which does not produce carbapenemase, did not cause infection after colonization, whereas the ST11 strain FK4758, which produces carbapenemase, caused infection after intestinal colonization. Our finding demonstrated that not all intestinal colonization of K. pneumoniae subsequently caused infections, and the infections of K. pneumoniae after colonization are different. Therefore, the infection models we established provided possibility for the estimation of host-microbial interactions.

Clinical, microbiological, and molecular epidemiological characteristics of Klebsiella pneumoniae-induced pyogenic liver abscess in southeastern China.

Background: Klebsiella pneumoniae-induced pyogenic liver abscess (KP-PLA) has emerged as a life-threatening disease worldwide. However, to date, a limited number of scholars have attempted to systematically elucidate the characteristics of KP-PLA. The aim of the present study was to analyze clinical, microbiological, and molecular epidemiological characteristics of KP-PLA patients in Southeastern China. Methods: The KP-PLA cases from a tertiary teaching hospital in China from January 2016 to December 2017 were systemically studied and elucidated comprehensively. The virulence factors, resistant spectrum, and clones of K. pneumoniae isolates were identified with string test, polymerase chain reaction (PCR), antimicrobial susceptibility test, and multilocus sequence typing. Moreover, the characteristics in KP-PLA patients with and without other hepatobiliary diseases (OHD) were also been compared. Results: A total of 163 KP-PLA cases were enrolled, in which the majority of those cases were senior males, and often associated with multiple underlying diseases, including diabetes (49.7%). The remaining cases belonged to healthy individuals (50.3%). The clinical symptoms were common but nonspecific, characterized by increased inflammatory parameters and abnormal liver function parameters. The abscess was often right-sided solitary presentation (58.3%). Cephalosporin or carbapenem plus metronidazole combined with percutaneous puncture or catheter drainage were favorable therapeutics. Although low resistance rates of commonly used antimicrobial drugs (< 10%) were observed, twelve strains were identified as multidrug resistant (MDR) strains, and were mainly isolated from the OHD patients. The hypermucoviscosity, as well as K1 and K2 serotypes accounted for 30.7, 40.5, and 19.0%, respectively. Except for iroN (24.5%) and magA (45.4%), the high prevalence of virulence genes (e.g. aerobactin, rmpA, mrkD, fimH, uge, ureA, entB, ybtA, kfuBC, and wcaG) was identified (68.7-100.0%). Additionally, ST23 was found as a predominant sequence type (ST; 38.7%), and three novel STs (ST3507, ST3508 and ST3509) were noted as well. Conclusions: The present study reported the abundant hvKp strains in KP-PLA, as well as convergence of hypervirulent and MDR K. pneumoniae isolates from the KP-PLA patients, particularly those cases with OHD. Given the various clinical manifestations and destructive pathogenicity, determination of the comprehensive characteristics of such isolates is highly essential to effectively carry out for optimal management and treatment of KP-PLA.

Evolution of resistance mechanisms and biological characteristics of rifampicin-resistant Staphylococcus aureus strains selected in vitro.

BACKGROUND: We aimed to determine the evolutionary pathways of rifampicin resistance in Staphylococcus aureus, and the impact of resistance mutations in the rpoB gene on fitness. METHODS: Three clinical strains and one reference strain were used to select for rifampicin-resistant S. aureus variants. The mutations responsible for rifampicin resistance in all of the selected isolates in vitro were investigated by polymerase chain reaction (PCR) and DNA sequencing. To compare the fitness cost of rpoB mutations against their corresponding original isolates, we performed bacterial growth curve assays, static biofilm assays, in vitro competition experiments and an infection model of Galleria mellonella larvae. RESULTS: We obtained four rifampicin-resistant S. aureus isolates that showed high levels of resistance to rifampicin with a minimal inhibitory concentration (MIC) of 128 mg/L, and all isolates had a mutation at position 481 (H481F/Y) in RpoB. A broth microdilution assay indicated that mutation of H481F/Y did not affect susceptibility to common antibacterial drugs but slightly increased the vancomycin MIC. To identify the pathways involved in the development of rifampicin resistance, 32 variants (eight mutants for each strain) and four original isolates were selected for gene sequencing. Different generations of isolates were found to harbor various mutations sites. Compared with the corresponding original isolates, an in vitro fitness assay of the variant isolates showed that growth and virulence were reduced, with a statistically significantly decreased fitness, whereas the capacity for biofilm formation was elevated. CONCLUSIONS: Our findings suggested that the acquisition of rifampicin resistance in S. aureus was dynamic and was associated with a significant fitness cost.

Resistance and Heteroresistance to Colistin in Pseudomonas aeruginosa Isolates from Wenzhou, China.

The goal was to investigate the mechanisms of colistin resistance and heteroresistance in Pseudomonas aeruginosa clinical isolates. Colistin resistance was determined by the broth microdilution method. Colistin heteroresistance was evaluated by population analysis profiling. Time-kill assays were also conducted. PCR sequencing was performed to detect the resistance genes among (hetero)resistant isolates, and quantitative real-time PCR assays were performed to determine their expression levels. Pulsed-field gel electrophoresis and multilocus sequence typing were performed. Lipid A characteristics were determined via matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS). Two resistant isolates and 9 heteroresistant isolates were selected in this study. Substitutions in PmrB were detected in 2 resistant isolates. Among heteroresistant isolates, 8 of 9 heteroresistant isolates had nonsynonymous PmrB substitutions, and 2 isolates, including 1 with a PmrB substitution, had PhoQ alterations. Correspondingly, the expression levels of pmrA or phoP were upregulated in PmrB- or PhoQ-substituted isolates. One isolate also found alterations in ParRS and CprRS. The transcript levels of the pmrH gene were observed to increase across all investigated isolates. MALDI-TOF MS showed additional 4-amino-4-deoxy-l-arabinose (l-Ara4N) moieties in lipid A profiles in (hetero)resistant isolates. In conclusion, both colistin resistance and heteroresistance in P. aeruginosa in this study mainly involved alterations of the PmrAB regulatory system. There were strong associations between mutations in specific genetic loci for lipid A synthesis and regulation of modifications to lipid A. The transition of colistin heteroresistance to resistance should be addressed in future clinical surveillance.

Chlorhexidine exposure of clinical Klebsiella pneumoniae strains leads to acquired resistance to this disinfectant and to colistin.

Chlorhexidine is widely used as a disinfectant in hospitals, which may impose a selective pressure on bacteria. This study aimed to determine whether continuous exposure to chlorhexidine could lead to adaptive resistance and cross-resistance as well as investigating potential resistance mechanisms. Three clinical Klebsiella pneumoniae strains susceptible to conventional antimicrobials were selected and were continuously cultured in broth with gradually increasing concentrations of chlorhexidine. Antimicrobial susceptibility was determined. Mechanisms of acquired resistance to chlorhexidine and colistin were analysed by PCR and reverse transcription quantitative PCR (RT-qPCR). Furthermore, fitness was assessed through growth curve assays. Increased resistance to chlorhexidine and colistin was observed in all strains. Expression of the cepA gene was upregulated in the adapted strains, suggesting that hyperexpression of CepA was probably the main mechanism of adaptive resistance to chlorhexidine. The amino acid substitutions Leu82Arg and Arg256Gly in PmrB were detected in all of the adapted strains, whilst Leu344Pro was only identified in one adapted strain, indicating that the PmrB substitution was responsible for the cross-resistant phenotype. Moreover, chlorhexidine adaptation might have an effect on bacterial growth.

Effects of sub-minimum inhibitory concentrations of ciprofloxacin on biofilm formation and virulence factors of Escherichia coli.

OBJECTIVE: To evaluate the influence of sub-minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) on biofilm formation and virulence factors of Escherichia coli clinical isolates. METHODS: Sub-MICs of CIP were determined using growth curve experiments. The biofilm-forming capacity of E. coli clinical isolates and E. coli ATCC 25922 treated or untreated with sub-MICs of CIP was assessed using a crystal violet staining assay. The biofilm structure of E. coli isolate was assessed with scanning electron microscopy (SEM). The expression levels of the virulence genes fim, usp, and iron and the biofilm formation genes of the pgaABCD locus were measured using quantification RT-PCR (qRT-PCR) in E. coli isolates and E. coli ATCC 25922. RESULTS: Based on our results, the sub-MICs of CIP were 1/4 MICs. Sub-MICs of CIP significantly inhibited biofilm formation of E. coli clinical isolates and E. coli ATCC 25922 (p<0.01). SEM analyses indicated that the biofilm structure of the E. coli changed significantly after treatment with sub-MICs of CIP. Expression levels of the virulence genes fim, usp, and iron and the biofilm formation genes of the pgaABCD locus were also suppressed. CONCLUSIONS: The results revealed that treatment with sub-MICs of CIP for 24h inhibited biofilm formation and reduced the expression of virulence genes and biofilm formation genes in E. coli.

Effects of sub-minimum inhibitory concentrations of ciprofloxacin on biofilm formation and virulence factors of Escherichia coli

ABSTRACT Objective: To evaluate the influence of sub-minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) on biofilm formation and virulence factors of Escherichia coli clinical isolates. Methods: Sub-MICs of CIP were determined using growth curve experiments. The biofilm-forming capacity of E. coli clinical isolates and E. coli ATCC 25922 treated or untreated with sub-MICs of CIP was assessed using a crystal violet staining assay. The biofilm structure of E. coli isolate was assessed with scanning electron microscopy (SEM). The expression levels of the virulence genes fim, usp, and iron and the biofilm formation genes of the pgaABCD locus were measured using quantification RT-PCR (qRT-PCR) in E. coli isolates and E. coli ATCC 25922. Results: Based on our results, the sub-MICs of CIP were 1/4 MICs. Sub-MICs of CIP significantly inhibited biofilm formation of E. coli clinical isolates and E. coli ATCC 25922 (p < 0.01). SEM analyses indicated that the biofilm structure of the E. coli changed significantly after treatment with sub-MICs of CIP. Expression levels of the virulence genes fim, usp, and iron and the biofilm formation genes of the pgaABCD locus were also suppressed. Conclusions: The results revealed that treatment with sub-MICs of CIP for 24 h inhibited biofilm formation and reduced the expression of virulence genes and biofilm formation genes in E. coli.