Abstract: nutrients Article Oxygen Sparing Effect of Bacteriotherapy in COVID-19 Giancarlo Ceccarelli 1 , Massimiliano Marazzato 1, *, Luigi Celani 1 , Francesca Lombardi 2 , Alessandra Piccirilli 3 , Massimo Mancone 4 , Vito Trinchieri 1 , Francesco Pugliese 5 , Claudio M. Mastroianni 1 and Gabriella d’Ettorre 1 1 2 3 4 5 *



 Citation: Ceccarelli, G.; Marazzato, M.; Celani, L.; Lombardi, F.; Piccirilli, A.; Mancone, M.; Trinchieri, V.; Pugliese, F.; Mastroianni, C.M.; d’Ettorre, G. Oxygen Sparing Effect of Bacteriotherapy in COVID-19. Nutrients 2021, 13, 2898. https:// doi.org/10.3390/nu13082898 Academic Editor: Leyuan Li Department of Public Health and Infectious Diseases Sapienza, University of Rome, 00185 Rome, Italy; giancarlo.ceccarelli@uniroma1.it (G.C.); luigi.celani@uniroma1.it (L.C.); vito.trinchieri@uniroma1.it (V.T.); claudiomaria.mastroianni@uniroma1.it (C.M.M.); gabriella.dettorre@uniroma1.it (G.d.) Department of Life, Health & Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy; francesca.lombardi@univaq.it Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; alessandra.piccirilli@univaq.it Department of Clinical Internal Anesthesiologic and Cardiovascular Sciences Sapienza, University of Rome, 00185 Rome, Italy; massimo.mancone@uniroma1.it Department of Anesthesia and Intensive Care Medicine, Sapienza University of Rome, 00185 Rome, Italy; francesco.pugliese@uniroma1.it Correspondence: massimiliano.marazzato@uniroma1.it Abstract: Background: We previously reported that severe COVID-19 patients had higher chances of survival and a reduced risk of developing respiratory failure when administered with the probiotic formulation SLAB51. This study aimed to investigate further bacteriotherapy mechanisms and how early they are activated. Methods: We performed an analysis on the blood oxygenation parameters collected in sixty-nine severe COVID-19 patients requiring non-invasive oxygen therapy and presenting a CT lung involvement ≥50%. Twenty-nine patients received low-molecular-weight heparin, azithromycin and Remdesivir. In addition, forty subjects received SLAB51. Blood gas analyses were performed before the beginning of treatments and at 24 h. Results: The patients receiving only standard therapy needed significantly increased oxygen amounts during the 24 h observation period. Furthermore, they presented lower blood levels of pO2 , O2 Hb and SaO2 than the group also supplemented with oral bacteriotherapy. In vitro data suggest that SLAB51 can reduce nitric oxide synthesis in intestinal cells. Conclusions: SARS-CoV-2 infected patients may present lesions in the lungs compromising their gas exchange capability. The functionality of the organs essential for these patients’ survival depends mainly on the levels of pO2 , O2 Hb and SaO2 . SLAB51 contains enzymes that could reduce oxygen consumption in the intestine, making it available for the other organs. Received: 11 July 2021 Accepted: 21 August 2021 Keywords: COVID-19; SLAB51; probiotics; nitric oxide; hypoxia Published: 23 August 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license..