Peritoneal dialysis-related peritonitis caused by Stephanoascus ciferrii: A Case Report.

Stephanoascus ciferrii, a conditional pathogenic fungus prevalent in nature, is more frequently encountered in patients with compromised immunity. However, the literature rarely reports infections caused by Stephanoascus ciferrii in peritoneal dialysis patients. Here, we detail the case of a 66-year-old female suffering from renal failure who experienced catheter-related infection during peritoneal dialysis. Dialysate turbidity prompted the detection of Stephanoascus ciferrii in both peritoneal dialysate and tubes through microbiological cultures. Subsequent treatment involved antifungal drugs and a transition to hemodialysis, resulting in the disappearance of peritonitis symptoms and the patient's discharge. In recent years, fungal infections, particularly dialysis-related infections, are on the rise. This marks the first reported case of catheter-related peritonitis infection caused by Stephanoascus ciferrii. Compared to bacterial infections, fungal infections pose challenges due to limited drug options, significant side effects, and prolonged treatment durations. Hence, prompt pathogen diagnosis and drug sensitivity testing are crucial for effective clinical treatment. In essence, this scientific case report underscores the uncommon occurrence of catheter-related peritonitis attributed to Stephanoascus ciferrii in a peritoneal dialysis patient with renal failure, emphasizing the distinctive management challenges and underscoring the critical significance of prompt diagnosis and suitable intervention in such instances.

Genetic characteristics of chromosomally integrated carbapenemase gene (blaNDM-1) in isolates of Proteus mirabilis.

OBJECTIVE: This study aims to conduct an in-depth genomic analysis of a carbapenem-resistant Proteus mirabilis strain to uncover the distribution and mechanisms of its resistance genes. METHODS: The research primarily utilized whole-genome sequencing to analyze the genome of the Proteus mirabilis strain. Additionally, antibiotic susceptibility tests were conducted to evaluate the strain's sensitivity to various antibiotics, and related case information was collected to analyze the clinical distribution characteristics of the resistant strain. RESULTS: Study on bacterial strain WF3430 from a tetanus and pneumonia patient reveals resistance to multiple antibiotics due to extensive use. Whole-genome sequencing exposes a 4,045,480 bp chromosome carrying 29 antibiotic resistance genes. Two multidrug-resistant (MDR) gene regions, resembling Tn6577 and Tn6589, were identified (MDR Region 1: 64.83 Kb, MDR Region 2: 85.64 Kbp). These regions, consist of integrative and conjugative elements (ICE) structures, highlight the intricate multidrug resistance in clinical settings. CONCLUSION: This study found that a CR-PMI strain exhibits a unique mechanism for acquiring antimicrobial resistance genes, such as blaNDM-1, located on the chromosome instead of plasmids. According to the results, there is increasing complexity in the mechanisms of horizontal transmission of resistance, necessitating a comprehensive understanding and implementation of targeted control measures in both hospital and community settings.

High-throughput fluorescence quantification method based on inner filter effect and fluorescence imaging analysis.

The application of the inner filter effect (IFE) in fluorescent substance determination is gaining popularity. In this paper, a theory of the fluorescence distribution along with the excitation light path is derived from our previous research about the spatial micro-element method. According to the relationship between the summation of fluorescence intensities along the vertical direction at a certain position on the excitation light path and the position, a high-concentration and wide-range fluorescent substance quantification method based on the IFE and fluorescence imaging analysis is proposed. Correspondingly, a high-throughput fluorescent substance quantification detection system is constructed. In order to validate the method, solutions of rhodamine B in different concentrations are used for principle validation, concentration prediction, and experimental investigation on the influence of integration time and lens distortion. The high-throughput system enables the simultaneous measurement of six samples, realizing the high-concentration and wide-range quantification of rhodamine B (100-600 mg/L) with high precision (R2 = 0.9992, MRE = 2.34 %). By setting the filter wheel, the system can measure the concentration of fluorescent substances with different emission wavelengths. The improvement of experimental device is expected to reduce the single sample capacity to tens of microliters and increase the overall sample quantity to tens or even hundreds. The proposed method and system are beneficial to fluorescence measurement in fields such as biomedicine and dye research and to the improvement of high-throughput fluorescence quantitative PCR instruments.

Whole-genome sequencing, multilocus sequence typing, and resistance mechanism of the carbapenem-resistant Pseudomonas aeruginosa in China.

Pseudomonas aeruginosa is a significant pathogen responsible for severe multisite infections with high morbidity and mortality rates. This study analyzed carbapenem-resistant Pseudomonas aeruginosa (CRPA) at a tertiary hospital in Shandong, China, using whole-genome sequencing (WGS). The objective was to explore the mechanisms and molecular characteristics of carbapenem resistance. A retrospective analysis of 91 isolates from January 2022 to March 2023 was performed, which included strain identification and antimicrobial susceptibility testing. WGS was utilized to determine the genome sequences of these CRPA strains, and the species were precisely identified using average nucleotide identification (ANI), with further analysis on multilocus sequence typing and strain relatedness. Some strains were found to carry the ampD and oprD genes, while only a few harbored carbapenemase genes or related genes. Notably, all strains possessed the mexA, mexE, and mexX genes. The major lineage identified was ST244, followed by ST235. The study revealed a diverse array of carbapenem resistance mechanisms among hospital isolates, differing from previous studies in mainland China. It highlighted that carbapenem resistance is not due to a single mechanism but rather a combination of enzyme-mediated resistance, AmpC overexpression, OprD dysfunction, and efflux pump overexpression. This research provides valuable insights into the evolutionary mechanisms and molecular features of CRPA resistance in this region, aiding in the national prevention and control of CRPA, and offering references for targeting and developing new drugs.

Live-attenuated virus vaccine defective in RNAi suppression induces rapid protection in neonatal and adult mice lacking mature B and T cells.

Global control of infectious diseases depends on the continuous development and deployment of diverse vaccination strategies. Currently available live-attenuated and killed virus vaccines typically take a week or longer to activate specific protection by the adaptive immunity. The mosquito-transmitted Nodamura virus (NoV) is attenuated in mice by mutations that prevent expression of the B2 viral suppressor of RNA interference (VSR) and consequently, drastically enhance in vivo production of the virus-targeting small-interfering RNAs. We reported recently that 2 d after immunization with live-attenuated VSR-disabled NoV (NoVΔB2), neonatal mice become fully protected against lethal NoV challenge and develop no detectable infection. Using Rag1-/- mice that produce no mature B and T lymphocytes as a model, here we examined the hypothesis that adaptive immunity is dispensable for the RNAi-based protective immunity activated by NoVΔB2 immunization. We show that immunization of both neonatal and adult Rag1-/- mice with live but not killed NoVΔB2 induces full protection against NoV challenge at 2 or 14 d postimmunization. Moreover, NoVΔB2-induced protective antiviral immunity is virus-specific and remains effective in adult Rag1-/- mice 42 and 90 d after a single-shot immunization. We conclude that immunization with the live-attenuated VSR-disabled RNA virus vaccine activates rapid and long-lasting protective immunity against lethal challenges by a distinct mechanism independent of the adaptive immunity mediated by B and T cells. Future studies are warranted to determine whether additional animal and human viruses attenuated by VSR inactivation induce similar protective immunity in healthy and adaptive immunity-compromised individuals.

Whole-genome sequencing of clinical isolates of Citrobacter Europaeus in China carrying blaOXA-48 and blaNDM-1.

OBJECTIVE: To analyze the clinical infection characteristics and genetic environments of resistance genes in carbapenem-resistant Citrobacter europaeus using whole-genome sequencing. METHODS: The susceptibility of two clinical isolates of C. europaeus (WF0003 and WF1643) to 24 antimicrobial agents was assessed using the BD Phoenix™ M50 System and Kirby-Bauer (K-B) disk-diffusion method. Whole-genome sequencing was performed on the Illumina and Nanopore platforms, and ABRicate software was used to predict resistance and virulence genes of carbapenem-resistant C. europaeus. The characteristics of plasmids carrying carbapenem-resistance genes and their genetic environments were analyzed. Single nucleotide polymorphisms were used to construct a phylogenetic tree to analyze the homology of these two C. europaeus strains with ten strains of C. europaeus in the NCBI database. RESULTS: The two strains of carbapenem-resistant C. europaeus are resistant to various antimicrobial agents, particularly carbapenems and ß-lactams. WF0003 carries blaNDM- 1, which is located on an IncX3 plasmid that has high homology to the pNDM-HN380 plasmid. blaNDM- 1 is located on a truncated Tn125. It differs from Tn125 by the insertion of IS5 in the upstream ISAba125 and the deletion of the downstream ISAba125, which is replaced by IS26. WF1643 carries blaOXA- 48 in a Tn1999 transposon on the IncL/M plasmid, carrying only that single drug resistance gene. Homology analysis of these two strains of C. europaeus with ten C. europaeus strains in the NCBI database revealed that the 12 strains can be classified into three clades, with both WF0003 and WF1643 in the B clade. CONCLUSION: To the best of our knowledge, this is the first study to report an IncX3 plasmid carrying blaNDM- 1 in C. europaeus in China. C. europaeus strains harboring carbapenem-resistance genes are concerning in relation to the spread of antimicrobial resistance, and the presence of carbapenem-resistance genes in C. europaeus should be continuously monitored.

18S rRNA sequencing and homology analysis of post-traumatic bloodstream infection with Saprochaete clavata (Magnusiomyces clavatus) and a case report.

We present a case of bloodstream infection with Saprochaete clavata following an abdominal steel impact injury in a 52-year-old man, whose non-healing abdominal wound was also highly suspected of being caused by Saprochaete clavata. Saprochaete clavata is a very uncommon fungal pathogen. Our case is distinctive in that previous reports have typically involved immunocompromised, malignant, or leukemic patients. In contrast, our case involved a middle-aged man in good health who had ileal perforation repair for gastrointestinal perforation. Post-surgery, Saprochaete clavata was isolated from the incision exudate and blood samples. The pathogen was characterized and the drug sensitivity test was performed, and based on their results a clinical treatment plan was devised. The combination antifungal treatment comprising voriconazole and caspofungin significantly controlled the patient's infection and gradually healed the wound. Therefore, early isolation and characterization are essential because invasive fungal diseases have a high death rate.

Infection Defects of RNA and DNA Viruses Induced by Antiviral RNA Interference.

Immune recognition of viral genome-derived double-stranded RNA (dsRNA) molecules and their subsequent processing into small interfering RNAs (siRNAs) in plants, invertebrates, and mammals trigger specific antiviral immunity known as antiviral RNA interference (RNAi). Immune sensing of viral dsRNA is sequence-independent, and most regions of viral RNAs are targeted by virus-derived siRNAs which extensively overlap in sequence. Thus, the high mutation rates of viruses do not drive immune escape from antiviral RNAi, in contrast to other mechanisms involving specific virus recognition by host immune proteins such as antibodies and resistance (R) proteins in mammals and plants, respectively. Instead, viruses actively suppress antiviral RNAi at various key steps with a group of proteins known as viral suppressors of RNAi (VSRs). Some VSRs are so effective in virus counter-defense that potent inhibition of virus infection by antiviral RNAi is undetectable unless the cognate VSR is rendered nonexpressing or nonfunctional. Since viral proteins are often multifunctional, resistance phenotypes of antiviral RNAi are accurately defined by those infection defects of VSR-deletion mutant viruses that are efficiently rescued by host deficiency in antiviral RNAi. Here, we review and discuss in vivo infection defects of VSR-deficient RNA and DNA viruses resulting from the actions of host antiviral RNAi in model systems.

Accurate correction method and algorithm of fluorescence secondary inner filter effect (sIEF) in fluorescence quantitative analysis.

Fluorescence spectroscopy is a reliable and widely used analytical method. The fluorescence inner filter effect (IFE) is one of the main obstacles in the application of fluorescence spectroscopy and an error source in fluorescence analysis, resulting in the fluorescence spectrum distortion, the spectral shape distortion, and the nonlinearity between fluorescence intensity and fluorophore concentration. An optimized parameter reflecting the self-absorption effect - the fluorescence attenuation absorption index of secondary inner filter effect (sIFE) nopt - is proposed in this paper. Considering the received fluorescence in a direction perpendicular to the incident light, it is related to the solute-solvent system of the fluorescent substance, neither the geometric parameters of the cuvette and the light beam nor the concentration of the fluorescent substance. nopt can accurately reflect the degree to which the fluorescence is affected by the sIFE and correct for any non-ideality of the shapes of excitation/emission beams. The principle and determination method of nopt are explained in detail. Accordingly, an algorithm for the fluorescence spectroscopic correction by nopt is designed. To verify the method, the fluorescence spectra and absorbance spectra of the solutions of fluorescein sodium, rhodamine B, rhodamine 6G, and chlorophyll-a with a series of concentration gradients were measured, respectively. The influence of solvent effect on sIFE correction was also studied. The experiments show that different solute-solvent systems of the fluorescent substances have their own nopt. The novel algorithm can determine the nopt, correct the intensity attenuation and the peak red-shift of the fluorescence spectrum caused by the sIFE, expand the linear range of the concentration predicted by the fluorescence intensity, reduce the error of the prediction model, and improve the measurement accuracy.

CFSA-AGD: An accurate crosstalk fluorescence spectroscopic decomposition method for identifying and quantifying FDOMs in aquatic environments.

Fluorescent substances exist in various aquatic environments and other environmental media. It is a critical task to identify the components accurately and quantify their contents precisely. Based on the Crosstalk Fluorescence Spectroscopy Analysis (CFSA) model, a fluorescence spectroscopic decomposition using the Alternating Gradient Descent (AGD) algorithm is developed. By reducing the residual error of the model through alternating iterations, the CFSA-AGD method achieves unsupervised model training and automatic spectroscopic decomposition without extra experimental operations such as dilution or absorbance measurement, exempting from tedious modeling process. The objectives of this work are to validate that the CFSA-AGD method can comprehensively address the decomposition of fluorescence spectral crosstalk. Furthermore, the novel method is applied to the spectroscopic decomposition of natural FDOMs in aquatic environments as a standard tool. The spectral data analyzing the performance of this method is verified and compared with the conventional methods through the experiment on standard samples. The results indicate that CFSA-AGD has higher spectroscopic decomposition accuracy and gives more abundant information on the characteristic spectra with less residual error than parallel factor analysis. This means that the fluorescence spectra of natural FDOMs can be decomposed into the characteristic fluorescence emission spectra of single components with higher accuracy and the characteristic fluorescence absorption spectra that cannot be obtained by the conventional methods. Meanwhile, it improves the analytical precision of the contents (from R2 ≥ 0.9778 to R2 ≥ 0.9920) and reduces the ultimate residual error by two orders of magnitude (from 1.42 × 10-1 to 4.68 × 10-3) when the method is used to estimate the measured fluorescence spectra.

Improving the accuracy of high-repetition-rate LIBS based on laser ablation and scanning parameters optimization.

Laser-induced breakdown spectroscopy system based on high-repetition-rate microchip laser (HR-LIBS) has been widely used in elemental analysis due to its high energy stability, good portability and fast spectral acquisition speed. However, repeated ablation on powder pellets like soil and coal using HR-LIBS system encounters the problem of serious decline in measurement accuracy. In this work, the relationship between laser ablation and scanning parameters, their correlation with spectral intensity, as well as the optimization approach were fundamentally studied. The correlations among the crater overlapping rate, crater depth and spectral intensity were obtained. An HR-LIBS system with microchip laser (4 kHz repetition rate, 100 µJ laser pulse energy) to perform repeated scanning ablation was established. A theoretical model of the ablation crater morphology for repeated scanning ablation was developed. By taking soil pellets as the experimental samples, the linear fitting curves of crater depth and the spectral intensity ratio were established with the R2 of 0.90∼0.99. The experimental results showed that as the crater depth developed during repeated ablation, the Si-normalized spectral intensity decreased, and thus the spectral repeatability decreased. It was found that by optimizing the overlapping rate to form a flat crater bottom, the confinement effect of the crater on the plasma could be avoided. As a result, the spectral repeatability was significantly improved. The relative standard deviation (RSD) of Si-normalized spectral intensity was improved from 5% to 0.6%. Finally, repeated ablation was performed with the optimized overlapping rate on soil pellets. The R2 of calibration curves of Fe, Mg, Ca, and Al were all above 0.993, and the average RSDs were between 0.5% and 1%. This study provides a fast, accurate, and stable method for the analysis of the samples consisting of various materials with high heterogeneity.

Antimicrobial resistance and molecular characterization of gene cassettes from class 1 integrons in Salmonella strains.

Introduction. The emergence of antibiotic-resistant Salmonella isolates is a global concern and has been attributed to the indiscriminate use of antibiotics in humans and animals. Integrons are mobile gene elements closely related to bacterial drug resistance. Among them, class 1 integrons containing various resistance gene cassettes could play an important role in disseminating and maintaining antibiotic resistance in Salmonella isolates.Hypothesis. Salmonella class 1 integrons have a relationship with Salmonella drug resistance.Aim. This study aims to investigate the distribution of class 1 integrons and their variable regional molecular characteristics, as well as the diversity of the promoters and drug sensitivity among Salmonella strains.Methodology. A total of 111 Salmonella strains, collected between 2018 and 2020, underwent fully automated bacterial identification using the VITEK 2 Compact system and an antibiotic sensitivity test. PCR was employed to screen class 1 integrase genes (IntI1) and integron variable regions, while promoter type and variable region gene cassette characteristics were determined using sequencing analysis.Results. A total of 24 IntI1-positive strains were detected in 111 Salmonella strains. Moreover, IntI1-positive strains exhibited statistically significant resistance to ceftazidime, ciprofloxacin, levofloxacin, ceftriaxone, trimethoprim/sulfamethoxazole and azithromycin compared to integron-negative strains (P<0.05). The multidrug resistance rate of IntI1-positive strains was significantly higher than that of negative strains. Variable regions were observed in 6 of the 24 IntI1-positive strains. Four gene cassettes were detected, namely dfrA17-aadA5, dfrA12-aadA2, aadA22 and aar-3-dfrA27. Finally, 3 types of class 1 integron variable region promoters were identified in 24 strains, including PcW, PcH1 and PcWTGN-10; they are all relatively weak promoters.Conclusion. The integron and the drug resistance genes carried by integron have a certain relationship with drug resistance.

Femoral prosthesis fracture after hip arthroplasty revision: A Case Report and Review of Literature.

RATIONALE: A solution revision prosthesis has a multilayer microporous Porocoat coating, and the availability of multiple stem body sizes ensures that the prosthesis is adapted to each patient's anatomical structure so that there a firm attachment with the bone cortex in the middle of the femur. Therefore, the Solution prosthesis is one of the most commonly used and most effective prostheses in total hip arthroplasty worldwide. PATIENT CONCERNS: We reported a case of a 54-year-old female patient with periprosthetic femoral fractures after hip arthroplasty. DIAGNOSIS: The case was identified as type B2 prosthesis loosening according to the Vancouver classification. INTERVENTIONS: We performed revision surgery on her using the Solution prosthesis. Seven months after the surgery, the patient developed a mid-femoral prosthesis fracture for no apparent reason. We performed a second revision surgery of the hip joint and allogeneic bone plate fixation. OUTCOMES: The patient was satisfied with the treatment. LESSONS: For patients with type B2 prosthesis loosening and prosthesis fracture, hip arthroplasty revision and an allogeneic bone plate could be used to ensure more stable support.

Antimicrobial Resistance and Molecular Characterization of Gene Cassettes from class 1 Integrons in Carbapenem-resistant Escherichia coli strains.

OBJECTIVE: To investigate the distribution of class 1 integrons and their variable regional molecular characteristics, as well as the diversity of promoter and drug sensitivity of CR-Eco (carbapenem-resistant E. coli) strains. METHOD: A total of 117 CR-Eco strains, collected between 2012.01 and 2019.12, underwent fully automated bacterial identification and sensitization using VITEK-2 Compact and supplemented by K-B assay. PCR was employed to screen for class 1 integrase genes and integron variable regions, while the promoter type and variable region gene cassette characteristics were determined by sequencing analysis. RESULTS: The positive rate of the class 1 integron of the CR-Eco strains was 83.70% (92/117) herein. Moreover, class 1 integrase-positive strains exhibited statistically significant resistance to aztreonam, ceftazidime, ciprofloxacin, ceftriaxone, gentamicin, meropenem, and trimethoprim-sulfamethoxazole compared to integron-negative strains (P < 0.05). Variable regions were observed in 77 of the 92 class 1 integrase-positive strains. In addition, seven gene cassettes were detected, namely dfrA17-aadA5, aadA22, dfrA12-aadA2, dfrA12, dfrA17, dfrA27 and aadA. Finally, five types of class 1 integron variable region promoters were identified in those 77 strains, including PcW, PcH1, PcWTGN-10, PcH1TGN-10, and P2, which were detected in 48, 18, 8, 2, and 1 strains, respectively. CONCLUSION: The primary integrator variable region gene cassettes of this class were dfrA and aadA. The integron-positive strains displayed simultaneous high resistance to multiple antimicrobial drugs. The integrator variable region promoters of the CR-Eco strains are primarily weak and can potentially form and spread drug resistance.

The crosstalk fluorescence spectroscopy analysis principle and an accurate fluorescence quantitative method for multi-composition fluorescence substances.

Fluorescence quantitative analysis methods are extensively used in biomedicine inspection, petrochemical industry, environmental monitoring, and many other fields in the past decades. When the analyte is composed of multiple compositions, the accuracy of the conventional method declines significantly due to the fluorescence spectral crosstalk. In this research, the interactions between the light and the multiple compositions are comprehensively analyzed. The concepts of the quenching due to mutual absorption and the fluorescence overlapping are considered, and the mechanism of multi-composition fluorescence emission under single-wavelength excitation light is analyzed theoretically. The mixture experiment and the dilution experiment are designed to illustrate that the quenching due to mutual absorption has a significant nonlinear impact on fluorescence quantitative analysis and the mechanism of fluorescence spectral crosstalk gives a good explanation for these experiments. Through the in-depth theoretical analysis, the computer simulation, and the experiments, a novel principle named the Crosstalk Fluorescence Spectroscopy Analysis (CFSA) is proposed and verified, which has much higher quantitative analysis accuracy (R2>0.99 and RMSE≤0.2) than the conventional methods when analyzing the multi-composition samples. Unlike many correction approaches to fluorescence spectroscopy, the novel CFSA can serve as a complete analysis method rather than a correction method. These concepts and the principle are expected to be applied in many practical analysis fields.

Mammalian viral suppressors of RNA interference.

The antiviral defense directed by the RNAi pathway employs distinct specificity and effector mechanisms compared with other immune responses. The specificity of antiviral RNAi is programmed by siRNAs processed from virus-derived double-stranded RNA by Dicer endonuclease. Argonaute-containing RNA-induced silencing complex loaded with the viral siRNAs acts as the effector to mediate specific virus clearance by RNAi. Recent studies have provided evidence for the production and antiviral function of virus-derived siRNAs in both undifferentiated and differentiated mammalian cells infected with a range of RNA viruses when the cognate virus-encoded suppressor of RNAi (VSR) is rendered nonfunctional. In this review, we discuss the function, mechanism, and evolutionary origin of the validated mammalian VSRs and cell culture assays for their identification.

Identification of positive and negative regulators of antiviral RNA interference in Arabidopsis thaliana.

Virus-host coevolution often drives virus immune escape. However, it remains unknown whether natural variations of plant virus resistance are enriched in genes of RNA interference (RNAi) pathway known to confer essential antiviral defense in plants. Here, we report two genome-wide association study screens to interrogate natural variation among wild-collected Arabidopsis thaliana accessions in quantitative resistance to the endemic cucumber mosaic virus (CMV). We demonstrate that the highest-ranked gene significantly associated with resistance from both screens acts to regulate antiviral RNAi in ecotype Columbia-0. One gene, corresponding to Reduced Dormancy 5 (RDO5), enhances resistance by promoting amplification of the virus-derived small interfering RNAs (vsiRNAs). Interestingly, the second gene, designated Antiviral RNAi Regulator 1 (VIR1), dampens antiviral RNAi so its genetic inactivation by CRISPR/Cas9 editing enhances both vsiRNA production and CMV resistance. Our findings identify positive and negative regulators of the antiviral RNAi defense that may play important roles in virus-host coevolution.

High sensitivity and wide range chlorophyll-a determination by simultaneous measurement of absorbance and fluorescence using a linear CCD.

In the determination of chlorophyll with the fluorescence method in the natural water, the suspended particles and colloids will seriously interfere with the incident light and the fluorescence. Based on the analysis of the interaction between light and the measured substances, a high sensitivity, wide range of chlorophyll-a concentration measurement strategy, which combines optical information of fluorescence and absorbance with the CCD integration time transformation method, is proposed. Correspondingly, a novel algorithm, which can significantly correct the attenuation of incident light due to the absorption of suspended particles and the deviation of detected fluorescence caused by the scattered light and reflected light, is proposed to realize turbidity compensation. For verification, a self-designed compact optical experimental device consisting of a single LED and a linear CCD was set up to obtain the fluorescence spectrum and absorbance spectrum simultaneously. The experimental results demonstrate that the compensation strategy can commendably compensate for the impact of the suspended particles. The relative error of chlorophyll-a measurement is less than 5%, even in a high turbidity environment. Furthermore, the minimum detection limit is significantly reduced from conventional 0.01 µg/L to 0.0025 µg/L in the range of 0.0025-130 µg/L with the CCD integration time transformation method, which improves the measurement sensitivity. This device and method have the potential to be applied to the in situ online measurement of chlorophyll-a concentration in natural water.

Antimicrobial Resistance and Molecular Characterization of Gene Cassettes from Class 1 Integrons in Escherichia coli Strains.

To investigate the antimicrobial resistance and molecular characterization of gene cassettes from class 1 integrons in Escherichia coli strains isolated from hospitalized patients. Bacterial identification was conducted using the Vitek-2 Compact system, and antimicrobial susceptibility analysis was performed using the Kirby-Bauer method. Class 1 integrons, integrase genes, the variable regions of integrons and promoters from the isolated E. coli were screened by polymerase chain reaction, and subjected to DNA sequencing. In total, 138 E. coli strains were collected from the hospitalized patients, most from urine specimens (41.30%, 57/138). Antimicrobial resistance to ampicillin (89.86%) was most prevalent, with 79.99% of strains being multidrug-resistant (MDR). The class 1 integron integrase intI1 gene was detected in 67.39% of the isolates (93/138). Three gene cassette arrays and 5 antimicrobial resistance gene cassettes were detected in 69 of the class 1 integron-positive strains. The most common gene cassette array was dfrA17-aadA5. Of the 93 intI1-positive strains, 5 different common promoters were detected. The most prevalent common promoter was PcH1, and most isolates contained the dfrA17-aadA5 gene cassette array. In summary, antimicrobial resistance and MDR were prevalent among E. coli isolates in our city Weifang in Shandong Provence China. Gene cassettes of the class 1 integron variable region mostly conferred resistance to traditional antimicrobials. Weak promoters in the variable regions were predominant in this study. Integrons pose a great threat to the treatment of MDR bacterial infections and further investigations are needed.

Mycobacterium mucogenicum Infection in a Patient with an Open Fracture: A Case Report.

Mycobacterium mucogenicum is a nontuberculous mycobacterium that is ubiquitous in nature. However, M. mucogenicum infection in patients with orthopedic trauma is rarely reported in the literature. Herein, we describe a 48 year old male Han Chinese patient whose right leg was squeezed by agricultural machinery, resulting in open tibial fractures. Postoperative antimicrobial treatment was administered because the wound had been contaminated by soil. However, no long-term wound closure occurred, and a culture of the wound exudation tested positive for M. mucogenicum. We established the clinical treatment plan according to the characteristics and drug sensitivity test results of M. mucogenicum, and the patient was discharged uneventfully. Increasingly, more reports of infection caused by nontuberculous mycobacteria are being published; however, to our knowledge, this is the first report of an orthopedic infection caused by M. mucogenicum. Because the treatment process of M. mucogenicum infection is long and complex, isolation and identification of M. mucogenicum are of great significance to effective clinical treatment.