Identification, Characterization, and Formulation of a Novel Carbapenemase Intended to Prevent Antibiotic-Mediated Gut Dysbiosis

Analysis and Validation of a Diagnostic Nomogram for Predicting the Risk of Acute Respiratory Failure for Non-HIV Related Pneumocystis Jirovecii Pneumonia Patients

Objective

Pneumocystis Pneumonia (PCP), primarily affecting individuals with weakened immune systems, is a severe respiratory infection caused by pneumocystis jirovecii and can lead to acute respiratory failure (ARF). In this article, we explore the risk factors of ARF and propose a prognostic model of ARF for PCP patients.

Methods

In this multi-center, retrospective study in 6 secondary or tertiary academic hospitals in China, 120 PCP patients were screened from the Dryad database for the development of a predictive model. A total of 49 patients from Peking University People's Hospital were collected for external validation. Crucial clinical features of these patients are selected applying univariate and multivariate logistic regression analysis. We established an intuitive nomogram. Receiver operating characteristic (ROC) curve, calibration curve, decision curve analysis (DCA) and clinical impact curve (CIC) were plotted to evaluate the model's performance.

Results

A cohort of 120 patients formed the training cohort for the development of the model, with 49 patients constituting the test cohort. Univariate and multivariate logistic regression analysis identified five risk factors associated with ARF, which are age, fever, dyspnea, high neutrophil count and use of antibiotics. A nomogram was then proposed based on these factors. The area under the ROC curve (AUROC) in the development group has reached 0.8576, while the validation group has an AUROC of 0.7372, indicating commendable ability for predicting ARF. In addition, results for Hosmer-Lemeshow test indicate the effectiveness of our model. Furthermore, DCA and CIC curves demonstrate excellent clinical benefit.

Conclusion

We present a nomogram for predicting ARF in non-HIV related PCP patients. The prognostic model may provide references in clinical medicine, promote timely treatment and improve therapeutic outcomes of PCP patients.

Gut Microbiota Modulation and Prevention of Dysbiosis as an Alternative Approach to Antimicrobial Resistance: A Narrative Review

Background: The importance of gut microbiota in human health is being increasingly studied. Imbalances in gut microbiota have been associated with infection, inflammation, and obesity. Antibiotic use is the most common and significant cause of major alterations in the composition and function of the gut microbiota and can result in colonization with multidrug-resistant bacteria. Methods: The purpose of this review is to present existing evidence on how microbiota modulation and prevention of gut dysbiosis can serve as tools to combat antimicrobial resistance. Results: While the spread of antibiotic-resistant pathogens requires antibiotics with novel mechanisms of action, the number of newly discovered antimicrobial classes remains very low. For this reason, the application of alternative modalities to combat antimicrobial resistance is necessary. Diet, probiotics/prebiotics, selective oropharyngeal or digestive decontamination, and especially fecal microbiota transplantation (FMT) are under investigation with FMT being the most studied. But, as prevention is better than cure, the implementation of antimicrobial stewardship programs and strict infection control measures along with newly developed chelating agents could also play a crucial role in decreasing colonization with multidrug resistant organisms. Conclusion: New alternative tools to fight antimicrobial resistance via gut microbiota modulation, seem to be effective and should remain the focus of further research and development.

How to: prophylactic interventions for prevention of Clostridioides difficile infection

BACKGROUND

Clostridioides difficile infection (CDI) remains the leading cause of healthcare-associated diarrhoea, despite existing guidelines for infection control measures and antimicrobial stewardship. The high associated health and economic burden of CDI calls for novel strategies to prevent the development and spread of CDI in susceptible patients.

OBJECTIVES

We aim to review CDI prophylactic treatment strategies and their implementation in clinical practice.

SOURCES

We searched PubMed, Embase, Emcare, Web of Science, and the COCHRANE Library databases to identify prophylactic interventions aimed at prevention of CDI. The search was restricted to articles published in English since 2012.

CONTENT

A toxin-based vaccine candidate is currently being investigated in a phase III clinical trial. However, a recent attempt to develop a toxin-based vaccine has failed. Conventional probiotics have not yet proved to be an effective strategy for prevention of CDI. New promising microbiota-based interventions that bind and inactivate concomitantly administered antibiotics, such as ribaxamase and DAV-132, have been developed. Prophylaxis of CDI with C. difficile antibiotics should not be performed routinely and should be considered only for secondary prophylaxis in very selected patients who are at the highest imminent risk for recurrent CDI (R-CDI) after a thorough evaluation. Faecal microbiota transplantation (FMT) has proved to be a very effective treatment for patients with multiple recurrences. Bezlotoxumab provides protection against R-CDI, mainly in patients with primary episodes and a high risk of relapse.

IMPLICATIONS

There are no proven effective, evidenced-based prophylaxis options for primary CDI. As for secondary prevention, FMT is considered the option of choice in patients with multiple recurrences. Bezlotoxumab can be added to standard treatment for patients at high risk for R-CDI. The most promising strategies are those aimed at reducing changes in intestinal microbiota and development of a new effective non-toxin-based vaccine.

Protecting the Microbiota

We examine 3 different approaches to protecting the gut microbiome: highly targeted antibiotics, antibiotic destruction, and antibiotic binding. Each approach shows promise to prevent the off-target effects of antibiotics on the gut microbiome.

Oral Metallo-Beta-Lactamase Protects the Gut Microbiome From Carbapenem-Mediated Damage and Reduces Propagation of Antibiotic Resistance in Pigs

Antibiotics can damage the gut microbiome, leading to serious adventitious infections and emergence of antibiotic resistant pathogens. Antibiotic inactivation in the GI tract represents a strategy to protect colonic microbiota integrity and reduce antibiotic resistance. Clinical utility of this approach was established when SYN-004 (ribaxamase), an orally-administered beta-lactamase, was demonstrated to degrade ceftriaxone in the GI tract and preserve the gut microbiome. Ribaxamase degrades penicillins and cephalosporin beta-lactams, but not carbapenems. To expand this prophylactic approach to include all classes of beta-lactam antibiotics, a novel carbapenemase, formulated for oral administration, SYN-006, was evaluated in a porcine model of antibiotic-mediated gut dysbiosis. Pigs (20 kg, n = 16) were treated with the carbapenem, ertapenem (ERT), (IV, 30 mg/kg, SID) for 4 days and a cohort (n = 8) also received SYN-006 (PO, 50 mg, QID), beginning the day before antibiotic administration. ERT serum levels were not statistically different in ERT and ERT + SYN-006 groups, indicating that SYN-006 did not alter systemic antibiotic levels. Microbiomes were evaluated using whole genome shotgun metagenomics analyses of fecal DNA collected prior to and after antibiotic treatment. ERT caused significant changes to the gut microbiome that were mitigated in the presence of SYN-006. In addition, SYN-006 attenuated emergence of antibiotic resistance, including encoded beta-lactamases and genes conferring resistance to a broad range of antibiotics such as aminoglycosides and macrolides. SYN-006 has the potential to become the first therapy designed to protect the gut microbiome from all classes of beta-lactam antibiotics and reduce emergence of carbapenem-resistant pathogens.