[Effects of rapid drug sensitivity testing for multidrug-resistant bacteria on the prognosis of patients with severe intra-abdominal infection]

Objective: To examine the clinical value of rapid detection of drug-resistant bacteria by immunochromatography and the effects of rapid detection on the prognosis of patients with severe intra-abdominal infection complicated by carbapenem-resistant Enterobacteriaceae (CRE) bloodstream infection. Methods: This was a retrospective cohort study. We analyzed clinical data of 73 patients with severe abdominal infections with sepsis or septic shock complicated by CRE bloodstream infection admitted to the general surgery department of Jinling Hospital between February 2022 and February 2023. Patients were divided into a colloidal gold immunochromatographic assay (GICA) group (17 patients) and conventional testing group (56 patients) based on whether a GICA for CRE had been performed on the patients' first blood culture sample during the diagnosis and treatment process. There were no statistically significant differences between the GICA and conventional testing groups in age ([55.9±17.3] vs. [47.6±16.4] years), sex ([16 men vs. one woman ] vs. [41 men vs. 15 women]), median Charlson comorbidity index (3.0[2.0,4.0] vs. 3.0[2.0, 4.8]), septic shock (10 vs. 39), or acute kidney injury (8 vs. 40) (all P>0.05). Both groups routinely underwent traditional bacterial identification and drug susceptibility testing. Additionally, patients in the GICA group were tested directly for positive blood cultures using a GICA carbapenemase test kit. The main outcomes were mortality rates on Days 28 and 90 after the first identification of CRE bloodstream infection in both groups. We also compared the microbial clearance rate, duration of hospitalization and intensive care unit stay, and time from onset of CRE bloodstream infection to initiation of targeted and appropriate antibiotics between the two groups. Results: The rate of microbial clearance of bloodstream infection was significantly greater in the GICA group than in the conventional testing group (15/17 vs. 34/56 [60.7%], χ2=4.476, P=0.034), whereas the 28-day mortality tended to be lower in the GICA than conventional testing group [5/17 vs. 44.6% [25/56], χ2=1.250, P=0.264). The 90-day mortality (8/17 vs. 53.6% [30/56], χ2=0.222, P=0.638), median duration of hospitalization (37.0 [18.0, 46.5] days vs. 45.5 [32.2, 64.8] days, Z=-1.867, P=0.062), and median duration of intensive care unit stay (18.0 [6.5, 35.0] days vs. 32.0 [5.0, 51.8] days, Z=-1.251, P=0.209). The median time between the onset of bloodstream infection and administration of antibiotics was 49.0 (38.0, 69.0) hours in the GICA group, which is significantly shorter than the 163.0 (111.8, 190.0) hours in the conventional testing group (Z=-5.731, P<0.001). The median time between the onset of bloodstream infection and administration of appropriate antibiotics was 40.0 (34.0, 80.0) hours in the GICA group, which is shorter than in the conventional testing group (68.0 [38.2, 118.8]) hours; however, this difference is not statistically significant (Z=-1.686, P=0.093). Conclusions: GICA can provide information on carbapenemase- producing pathogens faster than traditional drug sensitivity testing, enabling early administration of the optimal antibiotics. The strategy of 'carbapenemase detection first' for managing bacterial infection has the potential to improve prognosis of patients and reduce mortality rate.

[Treatment of open abdomen combined with entero-atmospheric fistula: A retrospective study]

Objective: The purpose of this study was to analyze the course and outcome of patients with combined entero-atmospheric fistulas in open abdomen treatment. Methods: In this retrospective observational study, we collected data on 214 patients with open abdomen complicated by entero-atmospheric fistulas admitted to Research Institute of General Surgery, Jinling Hospital, Affiliated Hospital of Medical School from January 2012 to January 2021. We collected their basic characteristics, aetiology, treatment plan, and prognosis, including the durations of hospitalization and open treatment, time to resumption of enteral nutrition, duration and prognosis of definitive surgery, and overall prognosis. Results: Of the 214 patients with open abdomen complicated with entero-enteral fistulas, 23 (10.7%) died (11 of multiple organ failure caused by abdominal infection, five of abdominal cavity bleeding, four of pulmonary infection, one of airway bleeding, one of necrotizing fasciitis, and one of traumatic brain injury). The remaining 191 underwent definitive surgery at our hospital. The patients who underwent definitive surgery were predominantly male (156 patients, 81.7%); their age was (46.5±2.5) years. Trauma and gastrointestinal tumors (120 cases, 62.8%) predominated among the primary causes. The reasons for abdominal opening were, in order, severe abdominal infection (137 cases, 71.7%, damage control surgery (29 cases, 15.2%), and abdominal hypertension (25 cases, 13.1%). Temporary abdominal closure measures were used to classify the participants into a skin-only suture group (104 cases) and a skin-implant group (87 cases). Compared with the skin-implant group, in the skin-suture-only group the proportion of male patients was lower (74.7% [65/87] vs. 87.5% [91/104], χ2=5.176, P=0.023), the mean age was older ([48.3±2.0] years vs. [45.0±1.9] years, t=-11.671, P<0.001), there were fewer patients with trauma (32.2% [28 /87] vs. 58.7% [61/104), χ2=13.337, P<0.001), intensive care stays were shorter ([8.9±1.0] days vs. [12.7±1.6] days, t=19.281, P<0.001), total length of stay was shorter ([29.3±2.0] days vs. [31.9±2.0] days, t=9.021,P<0.001), there was a higher percentage of colonic fistulas (18.4% [16/87] vs. 8.7% [9/104], χ2=3.948, P=0.047), but fewer multiple fistulas (11.5% [10/87] vs. 34.6% [36/104], χ2=14.440, P<0.001). As to fistula management, a higher percentage of fistula sealing methods using 3D-printed intestinal stents were implemented in the skin-only suture group (60.9% [53/87] versus 43.3% [45/104], χ2=5.907, P=0.015). Compared with the implant group, the skin-only suture group had a shorter mean time to performing provisional closure ( [9.5±0.8] days vs. [16.0±0.6] days, t=66.023, P<0.001), shorter intervals to definitive surgery ( [165.0±10.7] days vs. [198.9±8.3] days, t=26.644, P<0.001), and less use of biopatches (56.3% [49/87) vs. 71.2% [74/104], χ2=4.545, P=0.033). Conclusions: Open abdomen complicated with entero-enteral fistulas is more common in male, and is often caused by trauma and gastrointestinal tumor. Severe intra-abdominal infection is the major cause of open abdomen, and most fistulae involves the small intestine. Collection and retraction of intestinal fluid and 3D-printed entero-enteral fistula stent sealing followed by implantation and skin-only suturing is an effective means of managing entero-enteral fistulas complicating open abdominal cavity. Earlier closure of the abdominal cavity with skin-only sutures can shorten the time to definitive surgery and reduce the rate of utilization of biopatches.

Temperature-Dependent Tunneling in Furan Oligomer Single-Molecule Junctions

Two commonly observed charge transport mechanisms in single-molecule junctions are coherent tunneling and incoherent hopping. It has been generally believed that tunneling processes yield temperature-independent conductance behavior and hopping processes exhibit increasing conductance with increasing temperature. However, it has recently been proposed that tunneling can also yield temperature-dependent transport due to the thermal broadening of the Fermi energy of the contacts. In this work, we examine a series of rigid, planar furan oligomers that are free from a rotational internal degree of freedom to examine the temperature dependence of tunneling transport directly over a wide temperature range (78-300 K). Our results demonstrate conductance transition from a temperature-independent regime to a temperature-dependent regime. By examining various hopping and tunneling models and the correlation between the temperature dependence of conductance and molecular orbital energy offset from the Fermi level, we conclude thermally assisted tunneling is the dominant cause for the onset of temperature-dependent conductance in these systems.

[Analysis of the effect of transgluteal percutaneous drainage in the treatment of deep pelvic abscess]

Objective: To investigate the safety and feasibility of transgluteal percutaneous drainage using double catheterization cannula in the treatment of deep pelvic abscess. Methods: A retrospective analysis of the clinical data of patients who underwent transgluteal percutaneous drainage using double catheterization cannula with deep pelvic abscesses admitted to the Jinling Hospital from May 2017 to September 2020 was conducted. Seven patients were enrolled, including 5 males and 2 females, who aged 26-74 (median 53.0) years old, and all of them had digestive fistula. One male patient was punctured again due to the tube falling off, and a total of 7 patients underwent 8 times of transgluteal percutaneous drainage, all under the guidance of CT. The puncture and drainage steps of the double catheterization cannula group are as follows: (1) Locate the puncture point under CT in the lateral position; (2) Place the trocar into the abscess cavity; (3) Confirm that the trocar is located in the abscess cavity under CT; (4) Pull out the inner core and insert into the double catheterization cannula through the operating hole; (5) Confirmthat the double catheterization cannula is located in the abscess cavity under CT; (6) The double catheterization cannula is properly fixed to prevent it from falling off. The white blood cells, C-reactive protein (CRP), procalcitonin, and interleukin-6 (IL-6) of all patients before the drainage and 1 days, 3 days, and 5 days after the drainage were collected, as well as the bacterial culture results of the drainage fluid. The changes of various infection biomarkers before and after the drainage were compared. Results: All 7 patients were cured. No complications such as hemorrhage and severe pain were observed. The average time with drainage tube was 60.8 (18-126) days. Five patients finally underwent gastrointestinal reconstruction surgery due to gastrointestinal fistula. The median serum interleukin-6 of patients before drainage, 1 day, 3 days and 5 days after drainage were 181.6 (113.0, 405.4) μg/L, 122.2 (55.8, 226.0) μg/L, 59.2 (29.0,203.5) μg/L and 64.1 (30.0,88.4) μg/L, respectively.The level of serum interleukin-6 at 3 days and 5 days after drainage was significantly lower than before drainage (F=3.586, P=0.026). Although the white blood cell count, C-reactive protein, and procalcitonin decreased gradually after drainage compared with before drainage, the difference was not statistically significant (all P>0.05). Conclusion: Transgluteal percutaneous drainage with double catheterization cannula is simple and effective, and can be used for the treatment of deep pelvic abscess.

Controlling Contact Configuration of Carboxylic Acid-Based Molecular Junctions Through Side Group

In this paper, the contact configuration of single molecular junction is controlled through side group, which is explored by electrochemical jump-to-contact STM break junction. The conductance values of 2-methoxy-1,3-benzenedicarboxylic acid (2-M-1,3-BDC) is around 10-3.65 G0, which is different from that of 5-methoxy-1,3-benzenedicarboxylic acid (5-M-1,3-BDC) with 10-3.20 G0. Interestingly, the conductance value of 2-M-1,3-BDC is the same as that of 1,3-benzenedicarboxaldehyde (1,3-BDCA), while single molecular junctions of 5-M-1,3-BDC and 1,3-benzenedicarboxylic acid (1,3-BDC) give out similar conductance value. Since 1,3-BDCA binds to the Cu electrode through one oxygen atom, the dominated contact configuration for 1,3-BDC is through two oxygen atoms. The different conductance values between 2-M-1,3-BDC and 5-M-1,3-BDC can be attributed to the different contact configurations caused by the position of the side group. The current work provides a feasible way to control the contact configuration between the anchoring group and the electrode, which may be useful in designing future molecular electronics.

Low Tunneling Decay of Iodine-Terminated Alkane Single-Molecule Junctions

One key issue for the development of molecular electronic devices is to understand the electron transport of single-molecule junctions. In this work, we explore the electron transport of iodine-terminated alkane single molecular junctions using the scanning tunneling microscope-based break junction approach. The result shows that the conductance decreases exponentially with the increase of molecular length with a decay constant β_N = 0.5 per -CH₂ (or 4 nm^-1). Importantly, the tunneling decay of those molecular junctions is much lower than that of alkane molecules with thiol, amine, and carboxylic acid as the anchoring groups and even comparable to that of the conjugated oligophenyl molecules. The low tunneling decay is attributed to the small barrier height between iodine-terminated alkane molecule and Au, which is well supported by DFT calculations. The work suggests that the tunneling decay can be effectively tuned by the anchoring group, which may guide the manufacturing of molecular wires.

Detecting Electron Transport of Amino Acids by Using Conductance Measurement

The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM) break junction. Conductance measurement of alanine gives out two conductance values at 10^−1.85 G₀ (1095 nS) and 10^−3.7 G₀ (15.5 nS), while similar conductance values are also observed for aspartic acid and glutamic acid, which have one more carboxylic acid group compared with alanine. This may show that the backbone of NH₂–C–COOH is the primary means of electron transport in the molecular junction of aspartic acid and glutamic acid. However, NH₂–C–COOH is not the primary means of electron transport in the methionine junction, which may be caused by the strong interaction of the Au–SMe (methyl sulfide) bond for the methionine junction. The current work reveals the important role of the anchoring group in the electron transport in different amino acids junctions.

Comparative Study on Single-Molecule Junctions of Alkane- and Benzene-Based Molecules with Carboxylic Acid/Aldehyde as the Anchoring Groups

We have measured the alkane and benzene-based molecules with aldehyde and carboxylic acid as anchoring groups by using the electrochemical jump-to-contact scanning tunneling microscopy break junction (ECSTM-BJ) approach. The results show that molecule with benzene backbone has better peak shape and intensity than those with alkane backbone. Typically, high junction formation probability for same anchoring group (aldehyde and carboxylic acid) with benzene backbone is found, which contributes to the stronger attractive interaction between Cu and molecules with benzene backbone. The present work shows the import role of backbone in junction, which can guide the design molecule to form effective junction for studying molecular electronics.