Novel 1,3,5-Triazinyl Aminobenzenesulfonamides Incorporating Aminoalcohol, Aminochalcone and Aminostilbene Structural Motifs as Potent Anti-VRE Agents, and Carbonic Anhydrases I, II, VII, IX, and XII Inhibitors

A series of 1,3,5-triazinyl aminobenzenesulfonamides substituted by aminoalcohol, aminostilbene, and aminochalcone structural motifs was synthesized as potential human carbonic anhydrase (hCA) inhibitors. The compounds were evaluated on their inhibition of tumor-associated hCA IX and hCA XII, hCA VII isoenzyme present in the brain, and physiologically important hCA I and hCA II. While the test compounds had only a negligible effect on physiologically important isoenzymes, many of the studied compounds significantly affected the hCA IX isoenzyme. Several compounds showed activity against hCA XII; (E)-4-{2-[(4-[(2,3-dihydroxypropyl)amino]-6-[(4-styrylphenyl)amino]-1,3,5-triazin-2-yl)amino]ethyl}benzenesulfonamide (31) and (E)-4-{2-[(4-[(4-hydroxyphenyl)amino]-6-[(4-styrylphenyl)amino]-1,3,5-triazin-2-yl)amino]ethyl}benzenesulfonamide (32) were the most effective inhibitors with KIs = 4.4 and 5.9 nM, respectively. In addition, the compounds were tested against vancomycin-resistant Enterococcus faecalis (VRE) isolates. (E)-4-[2-({4-[(4-cinnamoylphenyl)amino]-6-[(4-hydroxyphenyl)amino]-1,3,5-triazin-2-yl}amino)ethyl]benzenesulfonamide (21) (MIC = 26.33 µM) and derivative 32 (MIC range 13.80–55.20 µM) demonstrated the highest activity against all tested strains. The most active compounds were evaluated for their cytotoxicity against the Human Colorectal Tumor Cell Line (HCT116 p53 +/+). Only 4,4’-[(6-chloro-1,3,5-triazin-2,4-diyl)bis(iminomethylene)]dibenzenesulfonamide (7) and compound 32 demonstrated an IC50 of ca. 6.5 μM; otherwise, the other selected derivatives did not show toxicity at concentrations up to 50 µM. The molecular modeling and docking of active compounds into various hCA isoenzymes, including bacterial carbonic anhydrase, specifically α-CA present in VRE, was performed to try to outline a possible mechanism of selective anti-VRE activity.

The evaluation of vancomycin-resistant enterococci and carbapenamase producing Klebsiella colonization among ICU-Hospitalized Patients

Background: Multi-drug resistant organisms, especially Vancomycin-Resistant Enterococcus (VRE) and Carbapenam Resistant Klebsiella pneumoniae (KPC), are serious health threat. Early detection of resistant bacteria colonization amongpatients in intensive care units (ICUs) not only enables effective treatment but more importantly prevents disease and limits transmission. Therefore, we aimed to to assess the frequency of VRE and KPC colonization via rectal swab sampling. Methods: The study was carried out in ICUs of a tertiary hospital. Two rectal swab samples were collected within the first 24 hours of admission and another one was taken every subsequent 15 days to test for for VRE and KPC carriage. Results: A total 316 rectal swab samples taken from 230 patients. Forty-seven patients were screened at least 2 times. 183 patients were not further screened due to discharge, exitus or transfer to other wards. Thirty-six patients (16%) were determinedto be VRE (+). The most frequently isolated strain was E. faecium (80.5%) and its most common genotype was VanA (87.5%). Seven patients (3%) were identified as KPC (+). OXA-48 type crbapenamase was confirmed in all KPC isolates. Conclusion: This study shows that VRE and KPC colonization continues to be a serious threat in ICUs. Keywords: Carbapenam resistant klebsiella pneumoniae; vancomycin-resistant enterococci; intensive care units.

794. The Role of the Environment in Healthcare-associated Transmission of Vancomycin Resistant Enterococcus: A Proof of Concept Study

Background Transmission of Vancomycin Resistant Enterococcus (VRE) from environment to patient and patient to patient can both occur in healthcare settings. Due to the COVID-19 pandemic, a cohort of exposed patients on an inpatient unit with an extensive VRE outbreak needed to switch physical locations with a non-exposed patient population. By comparing outcomes of both cohorts, we aimed to determine the role of the physical environment (both direct and indirect contact) as compared to the patient population, in ongoing VRE transmission. Methods From 10 March to 21 April 2021, 41 new nosocomial acquisitions of VRE were detected as part of a VRE outbreak on a 34-bed acute care unit. Prior to the switch of units, extensive cleaning of the unit was conducted including electrostatic adjuncts to standard cleaning and environmental swabbing for VRE yielded no positive surfaces. The exposed cohort included 3 of 30 patients with VRE while the non-exposed cohort had 0 of 28 VRE positive patients based on prevalence testing on 21 April 2021. Following the physical relocation of both cohorts on 22 April, 2021, prospective VRE screening was performed on both units for one month including on admission, discharge and weekly prevalence screening. Hand hygiene compliance rates on both units was measured using group electronic monitoring. Results Figure 1 depicts the timeline and number of VRE cases before and after the unit switch. Following relocation of the VRE exposed cohort to the new unit, no further VRE transmission was detected (0/235 VRE screens; 0 VRE cases per 1000 patient days). Conversely, there were new VRE transmissions (3/99 VRE screens, 5 VRE cases per 1000 patient days) in the non-exposed cohort. When the units resumed their original location, one additional case of VRE was identified in the exposed cohort upon return to their original location. These transmissions occurred despite HH compliance of 94% (141,610/150,706) during the entire study period on the outbreak unit, which was consistently higher than on the non-outbreak unit (141,589/227,136, 62%).Figure 1. Conclusion The environmental reservoir for VRE may be more important in transmission than the patient reservoir. These findings underscore the importance of environmental cleaning to contain VRE outbreaks. Disclosures All Authors: No reported disclosures

1221. Genomic Factors Affecting the Efficacy of Antimicrobial Therapy in Daptomycin-, Linezolid-, Vancomycin-Resistant Enterococcus faecium (DLVRE)

Background Nosocomial acquisition of vancomycin-resistant Enterococcus (VRE) is one of the most challenging problems in healthcare. As Enterococcus isolates are increasingly resistant to vancomycin, clinicians now rely on alternative antimicrobial therapies including linezolid and daptomycin (DAP) to treat infections. For multidrug-resistant (MDR) VRE, combination therapy with beta-lactams and daptomycin has been shown to be effective. Methods Following initiation of empiric DAP and ceftaroline (CPT) for an MDR E. faecium bloodstream infection (VRE_001), we aimed to determine if there existed in vitro synergy between both agents that supported their clinical use. Combination synergy testing was performed using E-test strips and minimal inhibitory concentrations (MICs) were read at 24 hours. For whole genome sequence-based analysis (WGS), genomic DNA from VRE_001 was used for both short read (Illumina MiSeq) and long-read sequencing (MinION, Nanopore). The complete genome was assembled and the NCBI AMRFinderPlus program used to identify known resistance mechanisms. Results Original MICs of VRE_001 from the clinical microbiology laboratory at Northwestern Memorial revealed an MDR E. faecium (Table 1). Combination synergy testing in the experimental laboratory revealed only modest amounts of synergy between CPT and DAP (Table 2). Following WGS, VRE_001 was identified as an ST-584 E. faecium with a 3.2 Mbp genome, including a single chromosome and five plasmids. WGS analysis revealed several mechanisms of antimicrobial resistance (Table 3) genetically supporting the observed MDR-DLVRE phenotype. Conclusion Our investigational antimicrobial testing allowed for real-time in vitro analysis of synergistic MICs in a case of DLVRE bacteremia. Despite the fact that in vitro testing of CPT and DAP did not support the clinical usage of combination antimicrobial therapy, the patient cleared their blood cultures. WGS of VRE_001 revealed a plethora of antimicrobial resistance mechanisms including three mutations that explain high levels of DAP resistance. Synergy testing is not routinely available in most clinical laboratories, but rapid implementation of investigational MIC testing paired with genomic analysis may one day successfully support real-time clinical decision making. Disclosures All Authors: No reported disclosures