Mortality Predictors in Acute Respiratory Distress Syndrome Renal Transplant Recipients With ESKAPE/rESKAPE Pneumonia

Risk Factors for E2SKAPE Infections and Mortality Among Liver Transplant Recipients

PURPOSE

Infections caused by Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp (ESKAPE) plus Escherichia coli (E2SKAPE), in particular multidrug-resistant (MDR) E2SKAPE infections, occur frequently and pose a life-threatening to liver transplant (LT) recipients. To prevent E2SKAPE infections and improve the prognosis of LT recipients, the identification of risk factors for E2SKAPE infections and mortality is necessary.

METHODS

E2SKAPE pathogens were isolated and identified from clinical samples following standard microbiological procedures. All episodes of E2SKAPE infections and mortality documented among LT recipients were analyzed.

FINDINGS

A total of 83 episodes of E2SKAPE infections, including 75 (90.4%) episodes of MDR-E2SKAPE infections, occurred in 23.1% (53/229) of LT recipients. E. faecium was the dominant causative bacterium (37/83; 44.6%). The most common site of infections was the urinary tract (14/53; 26.4%). Sixteen (7%) patients died within 2 months after LT, and 7 deaths were E2SKAPE infections-related. Multivariate logistic regression analysis revealed that female sex [odds ratio (OR) = 3.665, 95% confidence interval (CI): 1.614-8.321, P = 0.002], duration of surgery ≥ 400 min [OR = 2.328, 95%CI: 1.151-4.707, P = 0.019], intraoperative red blood cell (RBC) transfusion ≥ 12U [OR = 2.542, 95%CI: 1.218-5.306, P = 0.013] and indwelling urethral catheter use ≥ 3 days [OR = 3.96, 95%CI: 1.309-11.981, P = 0.015] were independent risk factors for E2SKAPE infections after LT, and that only exposure to more than 2 intravenous antibiotics post-LT [OR = 0.318, 95%CI: 0.15-0.674, P = 0.003] was negatively associated with acquisition of E2SKAPE infections. The predictors of crude mortality included female sex [OR = 4.822, 95%CI: 1.299-17.904, P = 0.019], creatinine on day 3 post-LT > 1.5 mg/dL [OR = 11.014, 95%CI: 2.985-40.637, P < 0.001], mechanical ventilation post-LT [OR = 10.724, 95%CI: 2.695-42.676, P = 0.001] and recipients with E2SKAPE infections [OR = 4.112, 95%CI: 1.169-14.47, P = 0.028].

IMPLICATIONS

A high incidence of E2SKAPE infections was noted in the early post-LT period. The most common infection site was the urinary tract, and the dominant pathogenic bacterium was E. faecium. Female sex, prolonged surgery time, massive RBC transfusion, or delayed urethral catheter removal were associated with E2SKAPE infections. Only exposure to more than 2 intravenous antibiotics post-LT was negatively related to the acquisition of E2SKAPE infections. The predictors of mortality included female sex, creatinine on day 3 post-LT>1.5 mg/dL, mechanical ventilation post-LT, and recipients with E2SKAPE infections.

The Association of Organ Preservation Fluid Pathogens with Early Infection-Related Events after Kidney Transplantation

(1) Background: The need to elucidate the microbial patterns in preservation fluid and explore their relationship with early infection-related events post kidney transplant and investigate antimicrobial resistance and the effects of preemptive antibiotic therapy. (2) Methods: This retrospective study analyzed the clinical data of 514 kidney transplant donors and 808 recipients from April 2015 to October 2020. Clinical data of donor and recipient characteristics, preservation fluid microbes, early infections (≤30 days), probable donor-derived infections (P-DDIs), antimicrobial resistance and preemptive antibiotic therapy was collected. (3) Results: The incidence of bloodstream (10.3% versus 5.2%, p = 0.006) and graft-site infections (9.7% versus 4.6%, p = 0.004) was significantly higher in recipients with culture-positive preservation fluid. In addition, recipients with ESKAPE pathogens or Candida species had a notably higher rate of bloodstream infections (14.1% versus 6.9%, p = 0.033) and graft-site infections (16.7% versus 3.5%, p < 0.01) than those with other positive pathogens. Preemptive antibiotic therapy decreased the bloodstream infection rate (11.8% versus 35.7%, p = 0.047) when preservation fluid was positive for ESKAPE pathogens. (4) Conclusions: Culture-positive preservation fluid has potential implications for kidney transplant recipients. ESKAPE pathogens or Candida species in preservation fluid as well as their antimicrobial resistance properties and non-preemptive antibiotic therapy could pose a risk of early infection-related events.

Reduced porin expression with EnvZ-OmpR, PhoPQ, BaeSR two-component system down-regulation in carbapenem resistance of Klebsiella Pneumoniae based on proteomic analysis

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has proven to be an urgent threat to human health. Proteomics (TMT/LC-MS/MS) and bioinformatics approaches were employed to explore the potential mechanisms underlying carbapenem resistance. Proteomic profiling of CRKP and susceptible KP (sKP) isolates revealed the involvement of outer membrane, beta-lactam resistance pathway, and two-component systems (TCSs) in carbapenem resistance. 27 CRKP strains and 27 susceptible Klebsiella pneumoniae strains were isolated from inpatients at the Second Xiangya Hospital, China to verify the mechanisms. Modified carbapenem inactivation method (mCIM) and PCR of common carbapenem resistance genes confirmed that 77.8% (21/27) of CRKP isolates were carbapenemase-producing. Porin decrease in CRKP isolates was found by SDS-PAGE and mRNA levels of major porins (OmpK35 and OmpK36). RT-qPCR detection of two-component systems (envZ, ompR, phoP, phoQ, baeS and baeR) revealed down-regulation of EnvZ-OmpR, PhoPQ, BaeSR TCSs. Expression of the TCSs, except ompR, were closely correlated with OMPs with the R-value >0.7. Together, this study reaffirmed the significance of the β-lactam resistance pathway in CRKP based on proteomic analysis. OmpK35/36 porin reduction and the controversial downregulation of EnvZ-OmpR, PhoPQ, and BaeSR TCSs were confirmed in carbapenem resistance of Klebsiella pneumoniae.

Plasma Insulin-like Growth Factor Binding Protein 7 Contributes Causally to ARDS 28-Day Mortality: Evidence From Multistage Mendelian Randomization

BACKGROUND

ARDS is a devastating syndrome with heterogeneous subtypes, but few causal biomarkers have been identified.

RESEARCH QUESTION

Would multistage Mendelian randomization identify new causal protein biomarkers for ARDS 28-day mortality?

STUDY DESIGN AND METHODS

Three hundred moderate to severe ARDS patients were selected randomly from the Molecular Epidemiology of ARDS cohort for proteomics analysis. Orthogonal projections to latent structures discriminant analysis was applied to detect the association between proteins and ARDS 28-day mortality. Candidate proteins were analyzed using generalized summary data-based Mendelian randomization (GSMR). Protein quantitative trait summary statistics were retrieved from the Efficiency and safety of varying the frequency of whole blood donation (INTERVAL) study (n = 2,504), and a genome-wide association study for ARDS was conducted from the Identification of SNPs Predisposing to Altered Acute Lung Injury Risk (iSPAAR) consortium study (n = 534). Causal mediation analysis detected the role of platelet count in mediating the effect of protein on ARDS prognosis.

RESULTS

Plasma insulin-like growth factor binding protein 7 (IGFBP7) moderately increased ARDS 28-day mortality (OR, 1.11; 95% CI, 1.04-1.19; P = .002) per log2 increase. GSMR analysis coupled with four other Mendelian randomization methods revealed IGFBP7 as a causal biomarker for ARDS 28-day mortality (OR, 2.61; 95% CI, 1.33-5.13; P = .005). Causal mediation analysis indicated that the association between IGFBP7 and ARDS 28-day mortality is mediated by platelet count (OR, 1.03; 95% CI, 1.02-1.04; P = .01).

INTERPRETATION

We identified plasma IGFBP7 as a novel causal protein involved in the pathogenesis of ARDS 28-day mortality and platelet function in ARDS, a topic for further experimental and clinical investigation.

Antibacterial Properties and Efficacy of a Novel SPLUNC1-Derived Antimicrobial Peptide, α4-Short, in a Murine Model of Respiratory Infection

The rise of superbugs underscores the urgent need for novel antimicrobial agents. Antimicrobial peptides (AMPs) have the ability to kill superbugs regardless of resistance to traditional antibiotics. However, AMPs often display a lack of efficacy in vivo. Sequence optimization and engineering are promising but may result in increased host toxicity. We report here the optimization of a novel AMP (α4-short) derived from the multifunctional respiratory protein SPLUNC1. The AMP α4-short demonstrated broad-spectrum activity against superbugs as well as in vivo efficacy in the P. aeruginosa pneumonia model. Further exploration for clinical development is warranted.

Multidrug resistance (MDR) by bacterial pathogens constitutes a global health crisis, and resistance to treatment displayed by biofilm-associated infections (e.g., cystic fibrosis, surgical sites, and medical implants) only exacerbates a problem that is already difficult to overcome. Antimicrobial peptides (AMPs) are a promising class of therapeutics that may be useful in the battle against antibiotic resistance, although certain limitations have hindered their clinical development. The goal of this study was to examine the therapeutic potential of novel AMPs derived from the multifunctional respiratory host defense protein SPLUNC1. Using standard growth inhibition and antibiofilm assays, we demonstrated that a novel structurally optimized AMP, α4-short, was highly effective against the most common group of MDR bacteria while showing broad-spectrum bactericidal and antibiofilm activities. With negligible hemolysis and toxicity to white blood cells, the new peptide also demonstrated in vivo efficacy when delivered directly into the airway in a murine model of Pseudomonas aeruginosa-induced respiratory infection. The data warrant further exploration of SPLUNC1-derived AMPs with optimized structures to assess the potential application to difficult-to-cure biofilm-associated infections.