Impact of the coronavirus disease 2019 pandemic on the incidence of other infectious diseases in the hematology hospital in Korea.

BACKGROUND/AIMS: Since the coronavirus disease 2019 (COVID-19) outbreak, hospitals have implemented infection control measures to minimize the spread of the virus within facilities. This study aimed to investigate the impact of COVID-19 on the incidence of healthcare-associated infections (HCAIs) and common respiratory virus (cRV) infections in hematology units. METHODS: This retrospective study included all patients hospitalized in Catholic Hematology Hospital between 2019 and 2020. Patients infected with vancomycin-resistant Enterococci (VRE), carbapenemase-producing Enterobacterales (CPE), Clostridium difficile infection (CDI), and cRV were analyzed. The incidence rate ratio (IRR) methods and interrupted time series analyses were performed to compare the incidence rates before and after the pandemic. RESULTS: The incidence rates of CPE and VRE did not differ between the two periods. However, the incidence of CDI increased significantly (IRR: 1.41 [p = 0.002]) after the COVID-19 pandemic. The incidence of cRV infection decreased by 76% after the COVID-19 outbreak (IRR: 0.240 [p < 0.001]). The incidence of adenovirus, parainfluenza virus, and rhinovirus infection significantly decreased in the COVID-19 period (IRRs: 0.087 [p = 0.003], 0.031 [p < 0.001], and 0.149 [p < 0.001], respectively). CONCLUSION: The implementation of COVID-19 infection control measures reduced the incidence of cRV infection. However, CDI increased significantly and incidence rates of CPE and VRE remained unchanged in hematological patients after the pandemic. Infection control measures suitable for each type of HCAI, such as stringent hand washing for CDI and enough isolation capacities, should be implemented and maintained in future pandemics, especially in immunocompromised patients.

Synthesis of α-(4-Oxazolyl)amino Esters via Brønsted Acid Catalyzed Tandem Reaction.

A one-step, Brønsted acid catalyzed tandem reaction for the synthesis of α-(4-oxazolyl)amino esters was developed. 4-Nitrobenzenesulfonic acid was found to be an efficient catalyst for the coupling of ethyl 2-oxobut-3-ynoates with amides to provide various α-(4-oxazolyl)amino esters. The experimental and X-ray crystallographic data suggest that a series of bond-forming reactions including imine formation, intermolecular Michael addition, and intramolecular Michael addition are involved to generate both the oxazole and amino acid functionalities.

Alkoxide Migration at a Nickel(II) Center Induced by a π-Acidic Ligand: Migratory Insertion versus Metal-Ligand Cooperation.

Two pathways of alkoxide migration occurring at a nickel(II) center supported by a PPP ligand (PPP- = P[2-PiPr2-C6H4]2-) are presented in this Article. In the first route, the addition of a π-acidic ligand to a (PPP)Ni alkoxide species reveals the formation of a P-O bond. This reaction occurs via metal-ligand cooperation (MLC) involving a 2-electron reduction at nickel. To demonstrate a P-O bond formation, a nickel(II) isopropoxide species (PPP)Ni(OiPr) (4) was prepared. Upon addition of a π-acidic isocyanide ligand CNtBu, a nickel(0) isocyanide species (PPOiPrP)Ni(CNtBu) (6b) was generated; P-O bond formation occurred via reductive elimination (RE). When CO is present, migratory insertion (MI) occurs instead. The reaction of 4 with CO(g) results in the formation of (PPP)Ni(COOiPr) (5), representing an alternative pathway. The corresponding RE product (PPOiPrP)Ni(CO) (6a) can be independently produced from the substitution reaction of {(PPOiPrP)Ni}2(µ-N2) (3) with CO(g). While two different carbonylation pathways in 4 seem feasible, C-O bond forming migratory insertion singly occurs. Regeneration of a (PPP)Ni moiety via a P-O bond cleavage was demonstrated by treating 3 with CO2(g). The formation of (PPP)Ni(OCOOiPr) (7) clearly shows that an isopropoxide group migrates onto the bound CO2 ligand, and a P-Ni moiety is regenerated.

Phosphinite-Ni(0) mediated formation of a phosphide-Ni(II)-OCOOMe species via uncommon metal-ligand cooperation.

Reversible transformations are observed between a phosphide-nickel(II) alkoxide and a phosphinite-nickel(0) species via a P-O bond formation coupled with a 2-e(-) redox change at the nickel center. In the forward reaction, the nickel(0) dinitrogen species (PP(OMe)P)Ni(N2) (2) and {(PP(OMe)P)Ni}2(µ-N2) (3) were formed from the reaction of (PPP)NiCl (1) with a methoxy anion. In the backward reaction, a (PPP)Ni(II) moiety was regenerated from the CO2 reaction of 3 with the concomitant formation of a methyl carbonate ligand in (PPP)Ni(OCOOMe) (7). Thus, unanticipated metal-ligand cooperation involving a phosphide based ligand is reported.