Genomic characteristics of cfr and fexA carrying Staphylococcus aureus isolated from pig carcasses in Korea.

The emergence of transferable linezolid resistance genes poses significant challenges to public health, as it does not only confer linezolid resistance but also reduces susceptibility to florfenicol, which is widely used in the veterinary field. This study evaluated the genetic characteristics of linezolid-resistant Staphylococcus aureus strains isolated from pig carcasses and further clarified potential resistance and virulence mechanisms in a newly identified sequence type. Of more than 2500 strains isolated in a prior study, 15 isolated from pig carcasses exhibited linezolid resistance (minimum inhibitory concentration ≥ 8 mg/L). The strains were characterized in detail by genomic analysis. Linezolid-resistant S. aureus strains exhibited a high degree of genetic lineage diversity, with one strain (LNZ_R_SAU_64) belonging to ST8004, which has not been reported previously. The 15 strains carried a total of 21 antibiotic resistance genes, and five carried mecA associated with methicillin resistance. All strains harbored cfr and fexA, which mediate resistance to linezolid, phenicol, and other antibiotics. Moreover, the strains carried enterotoxin gene clusters, including the hemolysin, leukotoxin, and protease genes, which are associated with humans or livestock. Some genes were predicted to be carried in plasmids or flanked by ISSau9 and the transposon Tn554, thus being transmittable between staphylococci. Strains carrying the plasmid replicon repUS5 displayed high sequence similarity (99%) to the previously reported strain pSA737 in human clinical samples in the United States. The results illustrate the need for continuous monitoring of the prevalence and transmission of linezolid-resistant S. aureus isolated from animals and their products.

Outcomes of open repair for descending thoracic and thoracoabdominal aortic aneurysm in recent 10 years: experience of a high-volume centre in Korea.

OBJECTIVES: Although recent studies and guidelines suggest the preferred outcomes after surgical repair of thoracic aortic aneurysm (TAA) and thoracoabdominal aortic aneurysm (TAAA), published results are limited to those from high-volume hospitals and based on old data gathered before optimal management was established. Here, we analysed our outcomes over the previous 10 years from cases of open TAA and TAAA repair to offer updated and real-world results of those complex procedures performed in a high-volume centre. METHODS: From November 2013 to April 2022, 212 consecutive adult patients who underwent open TAA and TAAA repair were enrolled. We analysed early and late outcomes after surgery, including postoperative complications and mortality. RESULTS: There were 154 (73%) men, and the median age at surgery was 61 years. Intraoperative death occurred in 1 patient due to uncontrolled bleeding. Nine patients (4%) died during follow-up, and the survival estimates at 5 years were 94 ± 3% and 95 ± 3% after descending TAA and TAAA repair, respectively. Ten patients (4%) suffered from spinal cord ischaemic injury (9 with paraplegia and 1 with paresthesia), but permanent paraplegia persisted in only 1 case. CONCLUSIONS: We report very low postoperative complication rates and excellent early and late survival rates after open TAA and TAAA repair from our recent 10-year data analysis. These findings may assist when choosing treatment options for these complicated diseases.

Totally Thoracoscopic Ablation in Patients With Recurrent Atrial Fibrillation After Catheter Ablation.

BACKGROUND: The objective of this study was to evaluate the efficacy and safety of totally thoracoscopic ablation (TTA) in patients with recurrent atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA). METHODS: From February 2012 to May 2020, 460 patients who underwent TTA were classified into two groups: CA (presence of RFCA history, n = 74) and nCA groups (absence of RFCA history, n = 386). Inverse probability of treatment weighting (IPTW) analyses were used to adjust for confounders. The primary endpoint was freedom from the composite of AF, typical atrial flutter, atypical atrial flutter and any atrial tachyarrhythmia, lasting more than 30 seconds during the follow-up. All patients were followed up at 3, 6, and 12 months via electrocardiogram and 24-hour Holter monitoring. RESULTS: Bilateral pulmonary vein isolation (PVI) was conducted in all patients and the conduction block tests were confirmed. In the CA group, difficult PVI occasionally occurred due to structural changes, such as pericardial adhesion and fibrosis of the pulmonary venous structure, caused by a previous catheter ablation. Early complications such as stroke and pacemaker insertion were not different between the two groups. The normal sinus rhythm was maintained in 70.1% (317/460) patients after a median follow-up period of 38.1 months. The IPTW-weighted Kaplan-Meier curves revealed that freedom from AF events at 5 years was 68.4% (95% confidence interval, 62.8-74.5) in the nCA group and 31.2% (95% confidence interval, 16.9-57.5) in the CA group (P < 0.001). In IPTW-weighted Cox regression, preoperative left atrial diameter, persistent or long-standing AF, the presence of congestive heart failure and catheter ablation history were associated with AF events. CONCLUSION: Patients in the CA group showed a higher recurrence rate of AF than those in the nCA group, while TTA was safely performed in both the groups.

A Comparative Study of Thoracoscopic Left Atrial Appendage Clipping vs Stapled Resection.

BACKGROUND: The left atrial appendage (LAA) is the predominant site of thrombus formation in atrial fibrillation (AF), which is associated with ischemic stroke. This study comparatively evaluated the complete LAA closure rates between LAA clipping and stapled resections. METHODS: The study included 333 patients who underwent thoracoscopic operation with both preoperative and postoperative computed tomographic scans. Propensity score matching (4:1 ratio) was applied, matching 90 LAA clipping patients with 206 stapled resection patients. The primary end point was complete LAA closure, defined as a residual LAA depth of <1 cm on computed tomographic images obtained 1 year postoperatively. RESULTS: No 30-day death was observed. Complete LAA closure was achieved in 85.9% (286 of 333) of patients. After propensity score matching, the clipping group demonstrated a significantly higher complete LAA closure rate than the stapled resection group (95.6% vs 83.0%, P = .003). The residual LAA stump depth was also shorter in the clipping group compared with the stapled resection group (2.9 vs 5.3 mm, P = .001). Two patients with a residual LAA stump exhibited an association with ischemic stroke during follow-up. CONCLUSIONS: The clipping group demonstrated a higher rate of complete LAA closure compared with the stapled resection group. Close monitoring of patients with residual LAA stumps is essential. Further research with larger cohorts is needed to elucidate impact of the residual LAA stump on thromboembolic events.

Surgery for Diaphragmatic Hernia Repair: A Longitudinal Single-Institutional Experience.

Background: This study analyzed and described the clinical characteristics and surgical outcomes of diaphragmatic hernia (DH) repair according to the operative approach. Methods: After excluding cases with a combined approach and hiatal hernias, we analyzed 26 patients who underwent DH repair between 1994 and 2018. The baseline and perioperative characteristics of the thoracic approach group and the abdominal approach group were described and analyzed. Results: Fifteen of the 26 patients were treated through the thoracic approach, including 5 patients who underwent video-assisted thoracic surgery (VATS). Eleven patients underwent the abdominal approach. The thoracic approach was associated with a longer duration of DH than the abdominal approach (2 vs. 0.1 months), herniation of the right-sided abdominal organs, and herniation of the retroperitoneal organs. During the median follow-up of 23 months, there was no recurrence of DH. Conclusion: The surgical approach should be chosen considering the duration of DH and the location of herniated organs. VATS might be a safe and feasible option for repairing DH.

Impact of Interatrial Septal Reconstruction on Atrial Tachyarrhythmia after Surgical Resection of Myxoma.

Background: Complete surgical excision is the only curative treatment for primary cardiac tumors. For wide excision, interatrial septal reconstruction (ISR) is commonly performed. We hypothesized that ISR may increase the risk of postoperative atrial tachyarrhythmia (AT) after surgical resection of cardiac myxoma. Methods: After excluding patients with a history of cardiac surgery and concomitant procedures unrelated to tumor resection and those with AT or permanent pacemakers, we finally enrolled 272 adult patients who underwent benign cardiac tumor surgery from 1995 to 2021 at our institution. They were divided into the ISR (n=184) and non-ISR (n=88) groups. The primary outcome was postoperative new-onset AT. Results: The study cohort predominantly consisted of women (66.2%), with a mean age of 57.2±13.6 years. The incidence of postoperative new-onset AT was 15.4%. No 30-day mortality or recurrence was observed. The cardiopulmonary bypass time and aortic cross-clamping time were significantly longer in the ISR group than in the non-ISR group (p<0.001). The median duration of hospital stay of all patients was 6.0 days (interquartile range, 5.0-7.0 days), and no significant difference was observed between the 2 groups (p=0.329). ISR was not an independent predictor of new-onset AT (p=0.248). Male sex and hypertension were found to be independent predictors of new-onset AT. Conclusion: ISR was not a significant predictor of postoperative new-onset AT. ISR might be a feasible and safe procedure for surgical resection of cardiac myxoma and should be considered if needed.

Heat-killed Limosilactobacillus reuteri PSC102 Ameliorates Impaired Immunity in Cyclophosphamide-induced Immunosuppressed Mice.

The immune functions of heat-killed Limosilactobacillus reuteri PSC102 (hLR) were investigated in cyclophosphamide (CP)-treated immunosuppressed mice. BALB/c mice were randomly divided into five groups: normal control group, CP group, CP treated with levamisole (positive control group), and CP treated with low- and high-dose hLR. After receiving the samples for 21 days, mice were sacrificed, and different parameters, such as immune organ index, immune blood cells, splenocyte proliferation, lymphocyte subpopulations, cytokines, and immunoglobulins, were analyzed. Results showed that the immune organ (thymus and spleen) indices of hLR treatment groups were significantly increased compared to the CP group (p < 0.05). hLR administration prevented CP-induced reduction in the numbers of white blood cells, lymphocytes, midrange absolute, and granulocytes, providing supporting evidence for hematopoietic activities. Splenocyte proliferation and T-lymphocyte (CD4+ and CD8+) subpopulations were also significantly augmented in mice treated with hLR compared to the CP group (p < 0.05). Moreover, Th1-type [interferon-γ, interleukin (IL)-2, and tumor necrosis factor-α] and Th2-type (IL-4 and IL-10) immune factors and immunoglobulin (IgG) showed significant increasing trends (p < 0.05). Additionally, the other proinflammatory cytokines (IL-1ß and IL-6) were also significantly elevated (p < 0.05). Taken together, this investigation suggested that orally administered hLR could recover immunosuppression caused by CP and be considered a potential immunostimulatory agent for the treatment of immunosuppressive disorders.

Mid-Term Results of Totally Thoracoscopic Ablation in Patients with Recurrent Atrial Fibrillation after Catheter Ablation.

BACKGROUND: We investigated the impact of previous catheter ablation (CA) on the midterm outcomes of totally thoracoscopic ablation in patients with lone atrial fibrillation (AF). METHODS: Between February 2012 and July 2018, 332 patients underwent totally thoracoscopic ablation for the treatment of AF (persistent AF; n=264, 80%). The patients were stratified into CA (n=47, 14%) and non-CA (nCA; n=285, 86%) groups according to their CA history. RESULTS: All the baseline clinical characteristics and risk factors were similar between the groups except for age, percentage of male patients, prevalence of paroxysmal AF, prior percutaneous coronary intervention, and left atrial volume index (LAVI). No significant intergroup differences were observed in the incidence of early and late complications. At late follow-up, normal sinus rhythm was observed in 92% (43 of 47) of the patients in the CA group and 85% (242 of 285) of the patients in the nCA group (p=0.268). The rate of freedom from AF recurrence at 5 years was 55.3%±11.0% in the CA group, which was similar to that in the nCA group (55.7%±5.1%, p=0.690). In Cox regression analysis, preoperative brain natriuretic peptide levels and LAVI were associated with AF recurrence, but CA history was not significant. CONCLUSION: Totally thoracoscopic ablation was safe and effective in treating AF irrespective of CA history. A history of CA did not appear to affect the procedural complexity.

Intact pap2 downstream of mcr-1 appears to be required for colistin resistance.

In this study, we investigated the effect of pap2 on colistin susceptibility using intact pap2 and truncated pap2 (pap2∆351) genes, which were found along with mcr-1 in plasmid. Our experiments based on conjugation, antibiotic susceptibility testing, and time-killing assay showed that an intact pap2 gene is necessary along with mcr-1 for reduced colistin susceptibility.

A Large Epiphrenic Esophageal Diverticulum Communicating with the Left Lower Lobe.

Epiphrenic diverticula are known to cause a series of complications. We report the case of a 54-year-old woman who was diagnosed with an epiphrenic diverticulum at a regular checkup in November 2006. Ten years later, she presented with massive hematemesis. Imaging studies revealed an epiphrenic diverticulum measuring 7.8 cm in diameter and a large amount of bleeding inside the diverticulum. Computed tomography showed fistula formation between the diverticulum and the left lower lobe of the lung, leading to the development of a pulmonary abscess. Diverticulectomy and 180° posterior partial fundoplication were performed transabdominally. The pulmonary abscess was treated with antibiotics alone. She was discharged 16 days after the operation without any complications over 7 months of follow-up.

Whole Sequences and Characteristics of mcr-1-Harboring Plasmids of Escherichia coli Strains Isolated from Livestock in South Korea.

Of 11 mcr-1-harboring plasmids previously identified from livestock in Korea, we performed whole plasmid sequencing on 3 plasmids and determined the genetic structure surrounding mcr-1 for all 11 plasmids. Transconjugation frequencies were measured for all mcr-1-harboring plasmids and competitive growth experiments were performed to investigate the fitness cost of each plasmid. Although they belong to different clones, the mcr-1-harboring plasmids, pEC006 and pEC019, were highly similar to the first identified mcr-1-carrying Incl2-type plasmid, pHNSHP45. Another IncX4-type plasmid, pEC111, had completely different structure from these plasmids, but was similar to pMCR1-IncX4. A nearly identical 11.3 kb mcr-1 region (nikB-ISApl1-mcr-1-pap2-topB) was shared by all mcr-1-harboring plasmids except pEC111. The transfer rate of mcr-1-harboring plasmids was highly variable (10-11 to 10-3) and was not related to plasmid structure. Competitive growth experiments revealed that the fitness of all three transconjugants with mcr-1-harboring plasmids increased compared with that of the recipient strain, Escherichia coli J53. The mcr-1-harboring plasmids may have been repeatedly introduced into bacterial isolates since the initial introduction of the mcr-1-positive strain from other countries into South Korea. Transferability and reduced burden to the host of mcr-1-harboring plasmid may lead to the proliferation of colistin-resistant isolates in the future. Therefore, continuous monitoring is necessary.