Dosimetric Analysis of CBCT-Based Weekly Online Adaptive Radiotherapy for Locally Advanced Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Anatomic and geometric changes are common during a radiotherapy course amongst patients receiving conventional fractionated radiotherapy for locally advanced non-small cell lung cancer (LA-NSCLC). These changes may cause significant deviation from initial reference plan resulting in over-treatment of normal tissue or under-coverage of the target. Cone-beam computed tomography (CBCT)-based online adaptive radiotherapy (ART) platforms allow for response to these changes and is being increasingly used in the clinic though less so for intrathoracic disease. We hypothesized weekly CBCT-ART would improve target coverage and decrease dose to organs at risk (OAR) in patients with LA-NSCLC.

MATERIALS/METHODS

Data was collected from a prospective registry of 23 LA-NSCLC patients treated to 60 Gy in 30 fractions with CBCT-ART between June 2021 and December 2022. For weekly ART (Wk-ART), online plan adaptation started on week two. The adapted plan was then used to treat patients with image guidance until the next ART. For comparison, doses were recalculated with the initial reference plan on the SCT with updated contours to derive non-adapted (non-ART) dosimetry for each week. The final dosimetric parameters were obtained by averaging weekly coverage (ITV, PTV) and critical OAR (Lung, esophagus, heart, spinal cord) doses for non-ART and weekly ART treatments respectively for each patient. Paired student t-test was performed to compare the dosimetric parameters between non-ART and Wk-ART.

RESULTS

We observed an average 29% ± 19% (median: 26%) reduction in ITV volume through the radiotherapy course, with 48% (11/23) of patients showing >30% reduction. Most significant volume reductions (16%) were observed between the third and fourth adaptation. Weekly ART showed significant (p<1×10-3) improvements in ITV and PTV coverage, and showed improved clinically relevant lung, esophageal, cardiac, and lung dosimetry (Table 1), especially in the later stages of treatment when the tumor showed significant shrinkage. The average time from contour review to quality assurance completed is 8.5±1.2 min.

CONCLUSION

CBCT-ART provides robust ART plan quality and efficient workflow. There are significant improvements in target coverage and OAR sparing in LA-NSCLC treated with weekly CBCT-ART and these are driven by the significant volume reduction of the ITV throughout treatment course.

The Role of CT-Based Radiomics Nomogram in Differential Diagnosis of Immune Checkpoint Inhibitor-Related Pneumonitis from Radiation Pneumonitis for Patients with ESCC

PURPOSE/OBJECTIVE(S)

The combination of immunotherapy and chemoradiotherapy has widely used for patients with esophageal squamous cell carcinoma (ESCC) and induced treatment-related adverse effects, particularly immune checkpoint inhibitor-related pneumonitis (CIP) and radiation pneumonitis (RP). The aim of this study is to differentiate between CIP and RP by the CT radiomics and clinical or radiological parameters.

MATERIALS/METHODS

A total of 76 ESCC patients with pneumonitis were enrolled in this retrospective study and divided into training dataset (n = 53) and validation dataset (n = 23). A total of 837 radiomics features were extracted from regions of interest (ROIs) based on the lung parenchyma window of CT images. A radiomics signature was constructed on the basis of the predictive features by the least absolute shrinkage and selection operator (LASSO). A logistic regression was applied to develop radiomics nomogram. Receiver operating characteristics (ROC) curve and area under the curve (AUC) were applied to evaluate the performance of pneumonitis etiology identification.

RESULTS

No significant difference was detected between training dataset and validation dataset. The radiomics signature which was made up of four radiomics features shown a favorable performance on differentiating between CIP and RP with the α-binormal-based and empirical AUC = 0.831 and 0.843. Patients with RP had a close relationship with location (p = 0.003) and shape of lesions (p = 0.002). The nomogram that combined with radiomics signature and clinical factors improved the classifying performance on discrimination in the training dataset (AUCαbin = 0.963 and AUCemp = 0.964). The results were verified in the validation dataset with AUC = 0.967 and 0.964.

CONCLUSION

CT-based radiomics features have potential values for differentiating between patients with CIP and RP. Addition of bilateral changes and sharp border produced superior model performance on classifying, which could be a useful method to improve related clinical decision-making.

Influence of Eyes Movement on Lens Dose during MR-Guided Radiotherapy for Brain Tumor

PURPOSE/OBJECTIVE(S)

Modern radiotherapy techniques achieve highly conformal target doses while avoiding organs at risk such as lens. The magnitude of eyes movement and its influence on lens dose is unclear. The lens dose is relevant for cataract formation. This study aims to evaluate the movement-range of lens and its influence on dose distribution during MR-guided radiotherapy for brain cancer patients.

MATERIALS/METHODS

Fifty patients with brain cancer who were treated with MR-guided radiotherapy on 1.5 T MR-Linac were included in this study. All patients underwent a pre-treatment MRI and post-treatment MRI for each fraction. The eyes and lens were delineated on each MR image by a radiation oncologist. The reference treatment plans based original CT were recalculated on each MRI by "adapt to position" workflow. Then, we created planning risk volume (PRV) for lens by adding population margin and reoptimized the reference plans to evaluate the dose changes for lens. Inter-fraction and intrafraction variability for eyes and lens were evaluated with the Dice similarity coefficient (DSC), the Hausdorff distance (HD) and mean distance to agreement (MDA). Differences in daily dose (Dmax and Dmean) for eyes and lens were assessed.

RESULTS

A total of 300 MR images were analyzed in this study. The eyes motion was observed (minimum DSC: 0.57; maximum HD: 10.53; maximum MDA: 3.13). And the obvious lens motion also was found (minimum DSC: 0.01; maximum HD: 10.78; maximum MDA: 5.68). The maximum dose changes for eyes were up to 34.1% and the mean dose changes were up to 18.1%. The maximum dose changes for lens were up to 97.9% and the mean dose changes for eyes were up to 89%. When the reoptimized plans were generated by PRV lens, the dose changes were decreased nearly to 0.

CONCLUSION

Eyes movements in all radiotherapy fractions result in higher lens doses and potentially increase cataract formation rate. Adding margin expansions in treatment planning, to account for eyes motion, is the feasible approach to limit lens dose.

Incidence of Major Depression, Suicidal Ideation, and Mental Health Treatment Amongst Cancer Survivors

PURPOSE/OBJECTIVE(S)

Receiving a cancer diagnosis and undergoing subsequent treatments can result in a significant psychological burden for cancer patients. However, there is conflicting literature on the incidence of major depression in cancer patients compared to patients without cancer. The purpose of this study was to investigate and further clarify the incidence of major depression, associated treatments, and suicidal ideation in cancer survivors compared to a non-cancer cohort.

MATERIALS/METHODS

This is a retrospective, population-based study using survey responses from the National Survey on Drug Use and Health collected from January 2015 to December 2019. Survey data sets were queried for all respondents aged 18 years or older who provided a cancer history. Patients with a reported history of cancer ("cancer survivors") were further stratified by whether they reported a "recent" cancer diagnosis within the past 12 months. Survey responses were then evaluated for recent diagnoses of and treatments for major depressive disorder and suicidal ideation. Rates were compared between cancer survivors and participants without cancer using the Pearson χ2 test and multivariable logistic regression models, respectively.

RESULTS

Among the 212,411 survey respondents identified, 7,635 (3.6%) reported a cancer history, with 1,486 (0.7%) reporting a recent cancer history. The incidence of major depression was not different between cancer survivors and participants without cancer (9.3% vs. 9.2%; p = 0.762), though the incidence was slightly higher amongst recent cancer survivors (10.0% vs. 9.2%; p = 0.259). Among patients diagnosed with major depression, cancer survivors were significantly more likely to receive treatment for depression (78.6% vs. 60.3%, p<0.001), with 72.6% discussing depressive symptoms with a medical professional and 64.3% receiving prescription medication. Suicidal ideation was significantly lower among cancer survivors (5.1% vs. 6.2%, p<0.001) including recent survivors (5.0% vs. 6.2%, p<0.001). Suicidal ideation was higher in patients with underlying major depression in both cancer survivors and participants without cancer (30.6% vs. 35.6%, p = 0.015). On logistic regression, respondents with underlying depression receiving treatment were more likely to have suicidal ideation (OR: 1.49; p<0.001) while having a cancer diagnosis did not correlate with suicidal ideation (OR: 0.87; p = 0.869).

CONCLUSION

There was no significant overall difference in the incidences of major depression between cancer survivors and patients without cancer. However, one consideration is the under-diagnosis depression among cancer survivors. Symptoms of depression may be overlooked and mistakenly attributed to appropriate grief from a cancer diagnosis. Among patients diagnosed with major depression, cancer survivors were more likely to receive treatment for depression. These results highlight the importance of early depression assessment and treatment for cancer survivors.

An Analysis of Patients Treated with Stereotactic Body Radiotherapy for Metastatic Urinary Tract Tumors to Identify Predictors of Response

PURPOSE/OBJECTIVE(S)

To identify selection criteria linked to outcomes in patients treated with stereotactic body radiotherapy (SBRT) for metastatic tumors of the urinary tract (UT).

MATERIALS/METHODS

Single institution retrospective analysis of SBRT treated patients for oligometastatic/progressive UT tumors from 2006-2022. Charts were queried for M1 status at diagnosis or during disease course, treatment details (surgery, SBRT, systemic therapy), metabolic status (diabetes [DM], BMI) and outcomes. A linear quadratic formula was used to calculate the biologically effective dose (BED) using an α/β of 10 for tumor. Descriptive statistics portrayed the cohort, and analyses were done at patient and site level. Time-to-event analyses, including overall survival (OS) and progression-free survival (PFS) from SBRT, were assessed by the Kaplan-Meier method. Cox regression was used for univariable (UVA) and multivariable analyses (MVA) to identify predictors of outcomes.

RESULTS

A total of 35 patients were treated at 44 metastatic sites, including: bone (25%), node (36.4%), lung (20.5%), soft tissue (13.6%) and liver (4.5%). Most were male (74.3%) with a median age of 70 (range: 51-89), without DM (60%) having a median BMI of 29.8, and ECOG <2 (97.1%) at time of SBRT. Six (17.1%) patients were M1 at diagnosis. Of the 29 non-M1 patients, 86.2% received definitive local therapy (LT), 58.6% had at least T3/N+ disease, 75.8% received systemic therapy with a median of 2 agents (range: 1-6) prior to SBRT. Sixteen (45.7%) received immunotherapy (IO) with most receiving this before (75%) and after (56.2%) SBRT. Six patients had positive PD-L1 status (n = 10). The median RT dose, fractionation and BED was 40 Gy (range: 14-46), 5 fractions, and 72 (range: 28-132), respectively. At a median follow-up of 34.8, the median OS was 18.4 m (range: 9.3-27.4) with a 2-year OS of 35.9%. At patient level, 62.8% recurred after SBRT. The median PFS after SBRT was 5.3 m (range: 1.8-8.7) with a 2-yr PFS of 29.3%. Patient-level PFS was improved with LT (6.7 vs 1.4 m; p = 0.001) and DM (NR vs 2.9 m; p = 0.015), whereas improved OS was related with LT (18.9 vs 6.6 m; p = 0.03), DM (p = 0.04), ECOG (p = 0.004), and no relapse after SBRT (NR vs 9.8 m; p <0.001). Exposure to < 3 systemic agents prior to SBRT portended better PFS (6.7 vs 2.6 m; p = 0.04) without any impact by IO. At site level, 20.4% of sites had local relapse with 4 being the first event. Site was related with PFS (p = 0.009) with order of increased relapse risk being liver > bone > soft tissue > node > lung. No dosimetric feature was related with recurrence risk. On MVA, both DM (p = 0.02) and LT (p = 0.002) were predictive for PFS. Only recurrence after SBRT predicted for OS on MVA (HR: 6.7, 95% CI: 1.4-31; p = 0.014). In the IO subset, median PFS was 5.3 m and OS was 9.4 m, with no difference seen with IO-SBRT sequence or PDL1 status.

CONCLUSION

Optimized selection criteria for metastasis-directed therapy in patients with UT tumors is unclear, notably with IO. Future studies may benefit by assessing circulating tumor markers prior to SBRT.

Machine Learning and Explainable Artificial Intelligence to Predict Occult Pelvic Nodal Metastases in Prostate Cancer

PURPOSE/OBJECTIVE(S)

Determination of risk of occult pelvic lymph node involvement (LNI) in patients with cN0 prostate cancer is critical for determination of optimal treatment options. Though several nomograms exist, machine learning (ML) approaches might enable physicians to better assess individual risk by incorporating multiple clinical risk factors. Herein, we developed a ML model to predict occult LNI, and explained its composition using an explainable artificial intelligence (XAI) framework.

MATERIALS/METHODS

Patients with cN0 prostate adenocarcinoma diagnosed from 2018-2020 were identified in the National Cancer Database. The query was limited to patients with known clinical staging and biopsy results who did not receive neoadjuvant therapy prior to pelvic nodal examination. Occult LNI was defined as pN1 disease based on surgical evaluation, with a minimum of 10 nodes examined. Five ML models were trained to predict LNI. Variables incorporated into the model were age, core biopsy results, Gleason scores, preoperative prostate specific antigen (PSA), and clinical T-stage. Model performance, measured using area under the receiver operator characteristic curve (AUC) on a holdout testing dataset, was compared to multivariable logistic regression. The best-performing model was explained using SHapley Additive exPlanation (SHAP) values. To permit more clinically-meaningful statistical interpretation, using a novel approach SHAP values were converted into odds ratios (OR), confidence intervals (CI), and p-values.

RESULTS

A total of 23,131 patients met inclusion criteria; 2,676 (11.6%) had occult LNI. The Extreme Gradient Boosting model outperformed all other models with an AUC of 0.82 (95% CI: 0.78-0.86) compared to 0.80 (95% CI: 0.76-0.84) for logistic regression. Increasing PSA (OR: 1.031; p<0.001), number of positive biopsy cores (OR: 1.055; p<0.001), and percent positive biopsy cores (OR: 1.01; p<0.001) were all associated with increased risk of LNI. Based on observation of SHAP dependence plots, risk of LNI plateaued at PSA>20 ng/dL and >11 positive cores, while no plateau was observed for percent positive biopsy cores. Relative to T1c disease, patients with T3b were at highest risk of LNI (OR: 1.461; p = 0.003). Gleason score of 9 was associated with significant risk of LNI (Ref: Gleason 6; OR: 1.891; p<0.001). This was primarily driven by the primary Gleason score; primary Gleason 5 disease was associated with significant risk of LNI (Ref: Gleason 3; OR: 1.915; p<0.001) while a secondary Gleason score of 5 was the only grade with significant increased risk of LNI (Ref: Gleason 3; OR: 1.185; p = 0.004). Age and number of cores examined were not significant predictors of LNI.

CONCLUSION

Our ML achieved improved performance relative to logistic regression at predicting occult LNI. XAI provided insight into the inner-working of the ML model. ML can be used to identify patients at risk for occult LNI and therefore inform clinical decision-making.

Multidisciplinary Management of Primary Urethral Cancer with Radiotherapy

PURPOSE/OBJECTIVE(S)

Primary urethral cancer (PUC) is a rare form of genitourinary malignancy with a paucity of data to guide management. We analyzed PUC patients for clinicopathologic characteristics and treatment approach (radiotherapy [RT] with/without consolidative surgery) to identify predictors of outcome and RT response.

MATERIALS/METHODS

We conducted a single-institution retrospective review of patients treated with RT for PUC between 2002 to 2020. Each patient underwent multidisciplinary evaluation (including cystoscopy) as well as imaging to confirm tumor origin in the urethra. The linear quadratic formula was used to calculate the biologically effective dose (BED) using an α/β of 10 for tumor. Descriptive statistics were used to characterize the cohort. Fisher's Exact test was used to compare groups. Time-to-event analyses was conducted with the Kaplan-Meier method; outcomes included overall survival (OS) and time to recurrence (TTR) from diagnosis. Cox regression analysis assessed predictors of outcomes.

RESULTS

A total of 17 patients were identified for analysis. Median age was 63 years (range: 34-86); the majority were female (76.5%) and white (82.4%). Tumors were localized in the proximal (n = 6) or distal (n = 11) urethra. Histology included urothelial (11.8%), squamous (35.3%), adenocarcinoma (29.4%) and mixed (23.5%). Ten patients (58.8%) had cT3 or higher disease with 10 being cN0 (58.8%), 1 cN1 (5.9%), 5 cN2 (29.4%) and 1 cNx (5.9%). Median tumor size was 4.8 cm (range: 0.5-12 cm). The majority (88.2%) were treated with definitive chemoRT with 70.5% receiving platinum therapy. Median RT dose was 59.4 Gy (range: 39.6-70.2) with a median of 30 fractions. One patient underwent upfront cystourethrectomy and 6 (35.3%) underwent consolidative surgery at a median of 2.3 months after RT. Five patients (29.4%) had a complete response (CR) and 70.6% had a partial response (PR) to RT. Of the 7 patients who underwent surgical resection the final pathology was ypTis (28.5%), ypT1 (14.2%), ypT2 (14.2%), ypT4 (28.5%) and pT2 (14.2%). A median of 16 lymph nodes were removed with 1 patient having pN2 and all others pN0. Four patients (66.6%) were downstaged by chemoRT prior to surgery. At a median follow-up time of 8.4 years, the median OS was 37.9 months (range: 23.2-52.7), which was associated with a 5-year OS of 37.2%. Twelve (70.5%) patients recurred with a median TTR of 6.3 months (range 4.8-7.7). No demographics, staging methods, or tumor characteristics were associated with OS or TTR. Urothelial histology was associated with CR following chemoRT (p = 0.02). RT dose (continuous) was associated with OS (p = 0.018) as well as a BED (HR: 0.90, 95% CI: 0.84-0.97; p = 0.01). A BED > 55 Gy was associated with improved median OS (56.4 vs 9.13 months, p = 0.006).

CONCLUSION

Analysis of PUC patients treated with multimodal therapy found higher rates of CR in patients with urothelial histology and increased OS in patients treated with a BED > 55 Gy. Neoadjuvant chemoRT may downstage disease prior to surgical extirpation.

The Feasibility of Level Ib Sparing Intensity Modulated Radiation Therapy in Nasopharyngeal Carcinoma Patients with High-Risk Factors: Based on International Guideline

PURPOSE/OBJECTIVE(S)

In spite of the rarity of level Ib recurrence after intensity-modulated radiation therapy, the International Guideline (IG) provides the risk factors for prophylactic coverage. In practice, however, there are significant differences between institutions. The purpose of this study is to examine the feasibility of sparing level Ib IMRT in NPC patients with high-risk factors based on IG.

MATERIALS/METHODS

From January 2014 to October 2017, newly-diagnostic, non-metastatic NPC patients in our center were retrospectively reviewed. According to the risk factors of prophylactic level Ib coverage in patients with negative level Ib recommended by IG, the characteristics of pre-treatment MRI were analyzed. Four high-risk factors were identified: a. involvement of the structures that drain to level Ib as first echelon (FES), including anterior half of nasal cavity, oral cavity, b. involvement of submandibular gland (SMG), c. with radiologic extranodal extension (rENE) in level II LNs, or d. maximal axial diameter (MAD)≧2 cm in level II LNs. Patients with risk factors were divided into Cohort A (with risk factors a), Cohort B (with risk factor b, but without a), and Cohort C (only with risk factors c and/or d). Recurrence rates of level Ib and regional relapse-free survival (RRFS) rates were evaluated in different cohorts.

RESULTS

A total of 961 patients were finally included. Thirty-six cases (3.7%) presented with radiologically positive level Ib metastasis. For the other patients with negative Ib LNs, there were 18, 65, 421, and 444 cases classified as FES involvement, SMG involvement, level II LNs with rENE, and level II nodal with MAD ≧2 cm. Excluding overlap, a total of 571 patients with risk factors were divided into three groups: Cohort A (n = 18), Cohort B (n = 49) and Cohort C (n = 504). Nine patients (9/961, 0.94%) developed level Ib recurrence. Except for 1 patient with positive Ib LNs at diagnosis, 2 did not meet any of the risk factors, while the other six (6/9, 66.7%) met at least one risk factor. The rate of recurrence at neck level Ib was highest in Cohort A (11.1%, 2/18; Ib-sparing group: 0/10, 0.0% vs Ib-covering group: 2/8, 25.0%; P = 0.183). In Cohort B, no cases were found with level Ib recurrence (0.0%, 0/49). In Cohort C, the rates were rare (0.8%, 4/504) in both groups (0.7%, 2/276 vs 0.9%, 2/228; P > 0.999). Among the three Cohorts, there were no significant differences in 5-year RRFS between two groups, which were 90.0% vs 62.5% (p = 0.248), 90.9% vs 92.0% (p = 0.905), and 92.6% vs 90.1% (p = 0.445), respectively. Among patients with high-risk factors, the incidence of grade 3-4 late dry mouth symptom was higher in the level Ib-covering group (3.1% vs 7.5%, P = 0.033).

CONCLUSION

Level Ib sparing appears safe and feasible for NPC patients with negative level Ib LNs, even if combined with risk factors: SMG involvement, and/or level II with rENE, and/or level II MAD ≧2 cm. Level Ib-sparing irradiation reduces dry mouth symptoms compared with level Ib-irradiation.

Isolation and Characterization of a Novel Recombinant Classical Pseudorabies Virus in the Context of the Variant Strains Pandemic in China

Pseudorabies virus (PRV) variants were discovered in immunized pigs in Northern China and have become the dominant strains since 2011, which caused huge economic losses. In this study, a classical PRV strain was successfully isolated in a PRV gE positive swine farm. The complete genome sequence was obtained using a high-throughput sequencing method and the virus was named JS-2020. The nucleotide homology analysis and phylogenetic tree based on complete genome sequences or gC gene showed that the JS-2020 strain was relatively close to the classical Ea strain in genotype II clade. However, a large number of amino acid variations occurred in the JS-2020 strain compared with the Ea strain, including multiple immunogenic and virulence-related genes. In particular, the gE protein of JS-2020 was similar to earlier Chinese PRV strains without Aspartate insertion. However, the amino acid variations analysis based on major immunogenic and virulence-related genes showed that the JS-2020 strain was not only homologous with earlier PRV strains, but also with strains isolated in recent years. Moreover, the JS-2020 strain was identified as a recombinant between the GXGG-2016 and HLJ-2013 strains. The pathogenicity analysis proved that the PRV JS-2020 strain has typical neurogenic infections and a strong pathogenicity in mice. Together, a novel recombinant classical strain was isolated and characterized in the context of the PRV variant pandemic in China. This study provided some valuable information for the study of the evolution of PRV in China.

Emergence of the fourth mobile sulfonamide resistance gene sul4 in clinical Salmonella enterica

The fourth mobile sulfonamide resistance gene sul4 has been discovered in many metagenomic datasets. However, there is no reports of it in cultured bacteria. In this study, a sul4 positive clinical Salmonella enterica SC2020597 was obtained by conventional Salmonella isolation methods and characterized by species identification and antimicrobial susceptibility testing. Meanwhile, the genomic DNA was sequenced using both long-read and short-read methods. Following that, the complete genome was analyzed by bioinformatic methods. The sul4 gene in S. enterica SC2020597 differed from the sul4 identified in metagenomic data by one amino acid and could confer full resistance to sulfamethoxazole. Genetic location analysis showed that the sul4 in SC2020597 was carried by a complex chromosomally integrated hybrid plasmid. ISCR20-like was strongly associated with the mobilization of sul4 by core genetic context analysis. To the best of our knowledge, this is the first report of the emergence of sul4 in clinically cultured S. enterica. More important, the sul4 has the potential to spread to other bacteria with the help of mobile elements.

Identification of tmexC3-tmexD3-toprJ1b in an XDR Providencia rettgeri clinical isolate co-producing NDM-1 and OXA-10 carbapenemases

OBJECTIVES

Emergence of carbapenemase and tigecycline resistance genes in pathogens threatens the efficacy of last-resort antibiotics. High attention should be paid to the spread and convergence of such resistance genes. This study reports an extensively drug-resistant (XDR) Providencia rettgeri clinical strain co-harbouring carbapenemase genes blaNDM-1, blaOXA-10 and the tmexCD3-toprJ1b gene cluster.

METHODS

The phenotype and genotype of P. rettgeri Pre20-95 were investigated by antimicrobial susceptibility testing, conjugation assay, stability testing and whole genome sequencing. Bioinformatics tools were used to uncover the genetic structures of its multidrug-resistant (MDR) plasmid pPre20-95-1 and SXT/R391 integrative and conjugative element ICEPreChn20-95.

RESULTS

P. rettgeri strain Pre20-95 was isolated from a human clinical infection and displayed an extensively drug-resistant (XDR) phenotype. Whole genome sequencing (WGS) analysis identified a pPrY2001-like MDR plasmid, namely pPre20-95-1, co-harbouring blaNDM-1 and blaOXA-10 genes in Pre20-95. The multidrug resistance region of pPre20-95-1 was composed of a Tn6625-derived module and a ∆Tn1696 structure, and blaNDM-1 and blaOXA-10 were located in a composite Tn structure consisting of insertion sequences ISCR1 and ISAba125 and an In125-like class 1 integron, respectively. Furthermore, the novel RND efflux pump gene cluster tmexCD3-toprJ1b was identified on the SXT/R391 ICE ICEPreChn20-95 of its chromosome, and reverse PCR showed that it could form a circular intermediate for transmission.

CONCLUSION

Our findings highlight further dissemination of the tmexCD3-toprJ1b gene cluster into a clinical isolate of P. rettgeri and convergence with multiple carbapenemase genes, which increases the risk of the emergence of XDR strains and threatens the treatment of Enterobacterales bacterial infections.

Genome characteristics of the optrA-positive Clostridium perfringens strain QHY-2 carrying a novel plasmid type

Clostridium perfringens is a bacterial species of importance to both public and animal health. The gene optrA is the first gene that confers resistance to the tedizolid, a last-resort antimicrobial agent in human medicine. Herein, we whole-genome sequenced and analyzed one optrA-positive C. perfringens strain QHY-2 from Tibetan sheep in Qinghai province and identified one optrA plasmid pQHY-2. The plasmid shared similar structure with the optrA-positive plasmids p2C45 and p21-D-5b previously identified in C. perfringens, demonstrating the potential horizontal transmission of the optrA plasmids among C. perfringens strains. Annotation of the optrA-positive plasmids showed optrA and erm(A) located on a segment flanked by IS element IS1216E, and fexA, optrA, and erm(A) located on a segment flanked by IS element ISVlu1, which revealed the possible dissemination mechanism. Additionally, a Tn6218-like transposon carrying aac(6')-aph(2″) and erm(B) was also detected on pQHY-2, demonstrating the transposition of Tn6218 and spread of antibiotic resistance among Clostridium bacteria. Molecular analysis indicated the optrA-positive plasmids belonged to a plasmid type distinct from the pCW3-like plasmids, pCP13-like plasmids, or pIP404-like plasmids. Further structure analysis showed they might be formed by inserting segments into plasmid pCPCPI53k-r1_1, which coexist with two pCW3-like plasmids and one pCP13-like plasmid in C. perfringens strain CPI 53k-r1 isolated from a healthy human in Finland. IMPORTANCE Antimicrobial resistance is now a global concern posing threats to food safety and public health. The pCW3-like plasmids can encode several main toxin genes and three antibiotic resistance genes (ARGs), including tetA(P), tetB(P), and erm(B), which used to be considered as the main carrier of ARGs in Clostridium perfringens. In this study, we found the optrA plasmids, which belonged to a novel plasmid type, could also harbor many other ARGs, indicating this type of plasmid might be the potential repository of ARGs in C. perfringens. Additionally, this type of plasmid could coexist with the pCW3-like plasmids and pCP13-like plasmids that encoded toxin genes associated with gastrointestinal diseases, which showed the potential threat to public health.

The characteristics of mcr-bearing plasmids in clinical Salmonella enterica in Sichuan, China, 2014 to 2017

Salmonella is one of the most important zoonotic pathogens and a major cause of foodborne illnesses, posing a serious global public health hazard. The emergence of plasmid-mediated mcr genes in Salmonella has greatly reduced the clinical choice of salmonellosis treatment. The aim of this study was to investigate the plasmid characteristics of mcr-positive Salmonella identified from patients in Sichuan, China during 2014 to 2017 by whole genomes sequencing. In this study, a total of 12 mcr-positive isolates (1.15%, ; mcr-1, n=10; mcr-3, n=2) were identified from 1046 Salmonella isolates using PCR. Further characterization of these isolates was performed through antimicrobial susceptibility testing, conjugation assays, whole genome sequencing, and bioinformatics analysis. The mcr-1 gene in these isolates were carried by three types of typical mcr-1-bearing plasmids widely distributed in Enterobacteriaceae (IncX4, IncI2 and IncHI2). Of note, two mcr-1-harboring IncHI2 plasmids were integrated into chromosomes by insertion sequences. Two mcr-3-bearing plasmids were IncC and IncFIB broad-host-range plasmids respectively. Genetic context analysis found that mcr-1 was mainly located in Tn6330 or truncated Tn6300, and mcr-3 shared a common genetic structure tnpA-mcr-3-dgkA-ISKpn40. Overall, we found that mcr gene in clinical Salmonella were commonly carried by broad-host plasmids and have potential to transfer into other bacteria by these plasmids. Continuous surveillance of MDR Salmonella in humans and investigation the underlying transmission mechanisms of ARGs are vital to curb the current severe AMR concern.

Exploring the Traditional Chinese Medicine (TCM) database chemical space to target I7L protease from monkeypox virus using molecular screening and simulation approaches

In the current study, we used molecular screening and simulation approaches to target I7L protease from monkeypox virus (mpox) from the Traditional Chinese Medicines (TCM) database. Using molecular screening, only four hits TCM27763, TCM33057, TCM34450 and TCM31564 demonstrated better pharmacological potential than TTP6171 (control). Binding of these molecules targeted Trp168, Asn171, Arg196, Cys237, Ser240, Trp242, Glu325, Ser326, and Cys328 residues and may affect the function of I7L protease in in vitro assay. Moreover, molecular simulation revealed stable dynamics, tighter structural packing and less flexible behaviour for all the complexes. We further reported that the average hydrogen bonds in TCM27763, TCM33057, TCM34450 and TCM31564I7L complexes remained higher than the control drug. Finally, the BF energy results revealed -62.60 ± 0.65 for the controlI7L complex, for the TCM27763I7L complex -71.92 ± 0.70 kcal/mol, for the TCM33057I7L complex the BF energy was -70.94 ± 0.70 kcal/mol, for the TCM34450I7L the BF energy was -69.94 ± 0.85 kcal/mol while for the TCM31564I7L complex the BF energy was calculated to be -69.16 ± 0.80 kcal/mol. Although, we used stateoftheart computational methods, these are theoretical insights that need further experimental validation.

[Notch signaling pathway inhibitor DAPT improves alcohol-induced neuronal differentiation impairment in zebrafish]

OBJECTIVE

To explore the role of the Notch signaling pathway in regulating neuronal differentiation and sensorimotor ability in a zebrafish model of fetal alcohol spectrum disorder.

METHODS

Zebrafish embryos treated with DMSO or 50 μmol/L DAPT (a Notch signaling pathway inhibitor) were examined for mortality rate, hatching rate, malformation rate, and body length at 15 days post fertilization (dpf). The mRNA expression levels of sox2, neurogenin1 and huc in the treated zebrafish embryos were detected using in situ hybridization and qRT-PCR, and their behavioral responses to strong light and vibration stimulation were observed. The zebrafish embryos were then exposed to DMSO, 1.5% ethanol, DAPT, or both ethanol and DAPT, and the changes in mRNA expression levels of sox2, neurogenin1, huc, and the Notch signaling pathway genes as well as behavioral responses were evaluated.

RESULTS

Exposure to 50 μmol/L DAPT significantly increased the mortality rate of 1 dpf zebrafish embryos (P < 0.01), decreased the hatching rate of 2 dpf embryos (P < 0.01), increased the malformation rate of 3 dpf embryos (P < 0.001), and reduced the body length of 15 dpf embryos (P < 0.05). DAPT treatment significantly downregulated sox2 mRNA expression (P < 0.01) and increased neurogenin1 (P < 0.05) and huc (P < 0.01) mRNA expressions in zebrafish embryos. The zebrafish with DAPT treatment exhibited significantly shortened movement distance (P < 0.001) and lowered movement speed (P < 0.05) in response to all the stimulation conditions. Compared with treatment with 1.5% ethanol alone, which obviously upregulated notch1a, her8a and NICD mRNA expressions in zebrafish embryos (P < 0.05), the combined treatment with ethanol and DAPT significantly increased neurogenin1 and huc mRNA expression, decreased sox2 mRNA expression (P < 0.01), and increased the moving distance and moving speed of zebrafish embryos in response to strong light stimulation (P < 0.05).

CONCLUSION

Ethanol exposure causes upregulation of the Notch signaling pathway and impairs neuronal differentiation and sensorimotor ability of zebrafish embryos, and these detrimental effects can be lessened by inhibiting the Notch signaling pathway.

Prevalence and Genomic Characteristics of mcr-Positive Escherichia coli Strains Isolated from Humans, Pigs, and Foods in China

Colistin is one of the last-resort antibiotics for treating infections caused by multidrug-resistant (MDR) Gram-negative bacteria. However, mcr genes conferring resistance to colistin have been widely identified, which is considered a global threat to public health. Here, we investigated the prevalence and characteristics of mcr-harboring Escherichia coli strains isolated from humans, animals, and foods in China by PCR, antimicrobial susceptibility testing, conjugation experiments, molecular typing, genome sequencing, and bioinformatics analysis. In total, 135 mcr-1-harboring E. coli isolates were acquired from 847 samples, and 6 isolates carried mcr-3. Among them, 131 isolates were MDR bacteria. Sixty-five resistance genes conferring resistance to multiple antimicrobials were identified in 135 isolates. The diverse pulsed-field gel electrophoresis (PFGE) patterns and sequence types (STs) of mcr-1-carrying isolates demonstrated that clonal dissemination was not the dominant mode of mcr-1 transmission. Seven types of plasmids were able to carry mcr-1 in this study, including IncI2, IncX4, IncHI2, p0111, IncY, and two hybrid plasmids. The genetic structures carrying mcr-1 of 60 isolates were successfully transferred into the recipient, including 25 IncI2 plasmids, 23 IncX4 plasmids, and an IncHI2 plasmid. mcr-1-pap2 was the dominant mcr-1-bearing structure, followed by ISApl1-mcr-1-pap2-ISApl1 (Tn6330) and ISApl1-mcr-1-pap2, among 7 mcr-1-bearing structures of 135 isolates. In conclusion, IncI2, IncX4, and IncHI2 plasmids were the major vectors spreading mcr-1 from different geographical locations and sources. The prevalence of Tn6330 may accelerate the transmission of mcr-1. Continuous surveillance of mcr-1 and variants in bacteria is vital for evaluating the public health risk posed by mcr genes. IMPORTANCE The spread of polymyxin-resistant Enterobacteriaceae poses a significant threat to public health and challenges the therapeutic options for treating infections on a global level. In this study, mcr-1-bearing ST10 E. coli was isolated from pigs, pork, and humans simultaneously, which demonstrated that ST10 E. coli was an important vehicle for the spread of mcr-1 among animals, foods, and humans. The high prevalence of mcr-1-positive E. coli strains in pigs and pork and the horizontal transmission of mcr-1-bearing plasmids in diverse E. coli strains suggest that pigs and pork are important sources of mcr-1-positive strains in humans and pose a potential threat to public health. Additional research on the prevalence and characteristics of mcr-1-positive E. coli is still required to facilitate early warning to improve polymyxin management in hospitals.

Genome-wide scans for selection signatures in indigenous pigs revealed candidate genes relating to heat tolerance

Heat stress is a major problem that constrains pig productivity. Understanding and identifying adaptation to heat stress has been the focus of recent studies, and the identification of genome-wide selection signatures can provide insights into the mechanisms of environmental adaptation. Here, we generated whole-genome re-sequencing data from six Chinese indigenous pig populations to identify genomic regions with selection signatures related to heat tolerance using multiple methods: three methods for intra-population analyses (Integrated Haplotype Score, Runs of Homozygosity and Nucleotide diversity Analysis) and three methods for inter-population analyses (Fixation index (F_ST), Cross-population Composite Likelihood Ratio and Cross-population Extended Haplotype Homozygosity). In total, 1 966 796 single nucleotide polymorphisms were identified in this study. Genetic structure analyses and F_ST indicated differentiation among these breeds. Based on information on the location environment, the six breeds were divided into heat and cold groups. By combining two or more approaches for selection signatures, outlier signals in overlapping regions were identified as candidate selection regions. A total of 163 candidate genes were identified, of which, 29 were associated with heat stress injury and anti-inflammatory effects. These candidate genes were further associated with 78 Gene Ontology functional terms and 30 Kyoto Encyclopedia of Genes and Genomes pathways in enrichment analysis (P < 0.05). Some of these have clear relevance to heat resistance, such as the AMPK signalling pathway and the mTOR signalling pathway. The results improve our understanding of the selection mechanisms responsible for heat resistance in pigs and provide new insights of introgression in heat adaptation.

Long-read metagenomic sequencing reveals that high-copy small plasmids shape the highly prevalent antibiotic resistance genes in animal fecal microbiome

The emergence and prevalence of animal-derived antibiotic resistance genes (ARGs) pose a great threat to public health globally. Long-read metagenomic sequencing is increasingly being used to decipher the fate of environmental ARGs. However, the investigations of the distribution, co-occurrence patterns, and host information of animal-derived environmental ARGs with long-read metagenomic sequencing have received little attention. To cover the gap, we employed a novel QitanTech nanopore long-read metagenomic sequencing method to perform a comprehensive and systematic investigation of the microbial communities and antibiotic resistance profiles, as well as to analyze the host information and genetic structures of ARGs in the feces of laying hens. Our results showed that highly abundant and diverse ARGs were detected in the feces of different ages of laying hens, indicating that feeding animal feces was an important reservoir for the enrichment and maintenance of ARGs. The distribution pattern of chromosomal ARGs was more strongly associated with fecal microbial communities than plasmid-mediated ARGs. Further long-read host tracking analysis revealed that ARGs from Proteobacteria are commonly located on plasmids, whereas in Firmicutes, they are usually carried by chromosomes. Co-occurrence analysis displayed that co-selection phenomena of different ARGs were common occurrences and highly active insertion sequences (ISs) could result in the serious prevalence of many ARGs. Notably, small high-copy plasmids played a significant role in the dissemination of several ARGs, such as floR and tet(L), which could disturb the compositions of fecal ARGs. Overall, our findings significantly expand our knowledge of the comprehensive landscape of feeding animal feces resistome, which is important for the prevention and management of multi-drug resistant bacteria in laying hens.

Gigantol restores the sensitivity of mcr carrying multidrug-resistant bacteria to colistin

BACKGROUND

The emergence and wide spread of plasmid-mediated colistin resistance gene (mcr-1) and its mutants have immensely limited the efficacy of colistin in treating multidrug-resistant (MDR) Gram-negative bacterial infections. The development of synergistic combinations of antibiotics with a natural product that coped with the resistance of MDR bacteria was an economic strategy to restore antibiotics activity. Herein, we investigated gigantol, a bibenzyl phytocompound, for restoring in vitro and in vivo, the sensitivity of mcr-positive bacteria to colistin.

METHODS

The synergistic activity of gigantol and colistin against multidrug-resistant Enterobacterales was studied via checkerboard assay and time-killing curve. Subsequently, the transcription and protein expression levels of mcr-1 gene were determined by RT-PCR and Western blots. The interaction of gigantol and MCR-1 was simulated via molecular docking and verified via site-directed mutagenesis of MCR-1. Hemolytic activity and cytotoxicity assay were used to evaluate the safety of gigantol. Finally, the in vivo synergistic effect was evaluated via two animal infection models.

RESULTS

Gigantol restored the activity of colistin against mcr-positive bacteria E.coli B2 (MIC from 4 μg/ml to 0.25 μg/ml), Salmonella 15E343 (MIC from 8 μg/ml to 1 μg/ml), K. pneumoniae 19-2-1 (MIC from 32 μg/ml to 2 μg/ml) carrying mcr-1, mcr-3, mcr-8, respectively. Mechanistic studies revealed that gigantol down-regulated the expression of genes involved in LPS-modification, reduced the MCR-1 products and inhibited the activity of MCR-1 by binding to amino acid residues Tyr287 and Pro481 in its D-glucose-binding pocket. Safety evaluation showed that the addition of gigantol relieves the hemolysis caused by colistin. Compared with monotherapy, the combination of gigantol and colistin significantly improved the survival rate of Gallgallella mellonella larvae and mice infected by E.coli B2. Moreover, there was a considerable decrease in the bacterial load present in the viscera of mice.

CONCLUSION

Our results confirmed that gigantol was a potential colistin adjuvant, and could be used to tackle multi-drug resistant Gram-negative pathogen infections combined with colistin.

Predictive value of DEEPVESSEL-fractional flow reserve and quantitative plaque analysis based on coronary CT angiography for major adverse cardiac events

AIM

To investigate the predictive value of the combination of DEEPVESSEL-fractional flow reserve (DVFFR) and quantitative plaque analysis using coronary computed tomographic angiography (CCTA) for major adverse cardiac events (MACE).

METHOD

In this retrospective study, data from 69 vessels from 58 consecutive patients were collected. These patients who underwent coronary angiography (CAG) with DVFFR were divided into MACE-positive and MACE-negative groups. DVFFR measurements were obtained from CCTA images acquired before CAG, and an FFR or DVFFR value ≤ 0.80 was considered haemodynamically significant. CCTA images were analysed quantitatively using automated software to obtain the following indices: total plaque volume (TPV) and burden (TPB), calcified plaque volume (CPV) and burden (CPB), non-calcified plaque volume (NCPV) and burden (NCPB), low-attenuation plaque (LAP), minimum lumen area (MLA), stenosis grade (SG) and lesion length (LL). Univariate and multivariate logistic regression, correlation, and receiver operating characteristic (ROC) analyses were used for statistical analysis.

RESULTS

DVFFR was highly correlated with invasive FFR (R=0.728), and the Bland-Altman plot showed good agreement between DVFFR and FFR (95% CI: -0.109-0.087) on a per-vessel level. DVFFR showed a high diagnostic performance in identifying abnormal haemodynamic vessels, with an area under the ROC curve (AUC) of 0.984. In multivariate analysis, the following biomarkers were predictors of MACE: DVFFR ≤ 0.8, SG, TPB, NCPB, and LL values. The combination of the above independent risk factors yielded the most valuable prediction for MACE (AUC:0.888).

CONCLUSIONS

DVFFR was highly correlated with FFR with satisfactory diagnostic accuracy. DVFFR, together with plaque analysis indices, yielded valuable predictions for MACE.

Global distribution and genomic characteristics of tet(X)-positive Escherichia coli among humans, animals, and the environment

In recent years, the plasmid-mediated transmission of the tigecycline resistance gene tet(X) in Escherichia coli has received considerable attention. However, studies on the global distribution of tet(X)-positive E. coli remain scarce. Herein, we performed a systematic genomic analysis of 864 tet(X)-positive E. coli isolates from humans, animals and the environment around the world. These isolates were reported in 25 countries and isolated from 13 different hosts. China reported the most tet(X)-positive isolates (71.76 %), followed by Thailand (8.45 %) and Pakistan (5.9 %). Pigs (53.93 %), humans (17.41 %), and chickens (17.41 %) were determined to be important reservoirs of these isolates. The sequence types (STs) of E. coli were highly diverse, with the ST10 clone complex (Cplx) being the most prevalent clone. Correlation analysis revealed a positive association between the antibiotic resistance genes (ARGs) in ST10 E. coli and the presence of insertion sequences and plasmid replicons; however, we found no significant correlation between ARGs and virulence genes. Furthermore, the ST10 tet(X)-positive isolates from multiple sources displayed a high degree of genetic similarity (<200 single-nucleotide polymorphisms [SNPs]) to the mcr-1-positive but tet(X)-negative human-derived isolates, suggesting clonal transmission. The most prevalent tet(X) variant in the E. coli isolates was tet(X4), followed by tet(X6)-v. Genome-wide association study (GWAS) indicated that compared to tet(X4), tet(X6)-v harbored more significantly different resistance genes. Notably, certain tet(X)-positive E. coli isolates from different geographical locations or hosts shared a few SNPs (<200 SNPs), indicating cross-contamination. Therefore, continuous global surveillance of tet(X)-positive E. coli is imperative in the future.

[Molecular epidemiology and clinical characteristics of six cases of CA-MRSA pneumonia after influenza]

Objective: To summarize and analyze the strains' molecular epidemiology and clinical characteristics of 6 strains of post-influenza community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) pneumonia. Methods: Six cases of CA-MRSA pneumonia after influenza from 2014 to 2022 were retrospectively collected and CA-MRSA strains from each patient were cultured. Then, SCCmec typing, MLST typing, and spa typing were performed on the samples, which also included the procedures for the detection of virulence factors. Antibiotic susceptibility test was then performed on all 6 strains. Results: ST59-t437-Ⅳ was the predominant type in all the strains of CA-MRSA(2/6). Leukocidin (PVL) was detected in 5 cases, and hemolysin α (HLAα) and phenol soluble regulatory protein α (PSMα) were detected in 6 cases. Five of the cases included in this study were diagnosed with severe pneumonia. In terms of treatment, 4 cases received antiviral therapy, and 5 patients with severe pneumonia received anti-infection treatment with vancomycin as the first choice and were discharged after improvement of their condition. Conclusions: The molecular types and virulence factors of CA-MRSA after influenza infection could vary considerably. Our experiments also showed that secondary CA-MRSA infection after influenza was more common in young people with no underlying diseases and could cause severe pneumonia. Vancomycin and linezolid were the first-line drugs for treating CA-MRSA infection and were highly effective in improving the condition of diagnosed patients. We highlighted the importance of referring patients with severe pneumonia after influenza for etiological tests to determine whether they had CA-MRSA infection, so that they could be properly treated with anti-influenza agents and receive appropriate anti-CA-MRSA infection treatment.

Development and validation of a prediction model for unsuccessful treatment outcomes in patients with multi-drug resistance tuberculosis

BACKGROUND

The World Health Organization has reported that the treatment success rate of multi-drug resistance tuberculosis is approximately 57% globally. Although new drugs such as bedaquiline and linezolid is likely improve the treatment outcome, there are other factors associated with unsuccessful treatment outcome. The factors associated with unsuccessful treatment outcomes have been widely examined, but only a few studies have developed prediction models. We aimed to develop and validate a simple clinical prediction model for unsuccessful treatment outcomes in patients with multi-drug resistance pulmonary tuberculosis (MDR-PTB).

METHODS

This retrospective cohort study was performed between January 2017 and December 2019 at a special hospital in Xi'an, China. A total of 446 patients with MDR-PTB were included. Least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression were used to select prognostic factors for unsuccessful treatment outcomes. A nomogram was built based on four prognostic factors. Internal validation and leave-one-out cross-validation was used to assess the model.

RESULTS

Of the 446 patients with MDR-PTB, 32.9% (147/446) cases had unsuccessful treatment outcomes, and 67.1% had successful outcomes. After LASSO regression and multivariate logistic analyses, no health education, advanced age, being male, and larger extent lung involvement were identified as prognostic factors. These four prognostic factors were used to build the prediction nomograms. The area under the curve of the model was 0.757 (95%CI 0.711 to 0.804), and the concordance index (C-index) was 0.75. For the bootstrap sampling validation, the corrected C-index was 0.747. In the leave-one-out cross-validation, the C-index was 0.765. The slope of the calibration curve was 0.968, which was approximately 1.0. This indicated that the model was accurate in predicting unsuccessful treatment outcomes.

CONCLUSIONS

We built a predictive model and established a nomogram for unsuccessful treatment outcomes of multi-drug resistance pulmonary tuberculosis based on baseline characteristics. This predictive model showed good performance and could be used as a tool by clinicians to predict who among their patients will have an unsuccessful treatment outcome.

Branching of High-Current Relativistic Electron Beam in Porous Materials

Propagation of high-current relativistic electron beam (REB) in plasma is relevant to many high-energy astrophysical phenomena as well as applications based on high-intensity lasers and charged-particle beams. Here, we report a new regime of beam-plasma interaction arising from REB propagation in medium with fine structures. In this regime, the REB cascades into thin branches with local density a hundred times the initial value and deposits its energy 2 orders of magnitude more efficiently than that in homogeneous plasma, where REB branching does not occur, of similar average density. Such beam branching can be attributed to successive weak scatterings of the beam electrons by the unevenly distributed magnetic fields induced by the local return currents in the skeletons of the porous medium. Results from a model for the excitation conditions and location of the first branching point with respect to the medium and beam parameters agree well with that from pore-resolved particle-in-cell simulations.