Synthesis, characterization, antimicrobial activity and molecular docking studies of combined pyrazol-barbituric acid pharmacophores

Purpose: To synthesize, and determine the antibacterial activity and binding mode of new pyrazolbarbituric acid derivatives in a search for new antimicrobial agents.Methods: One-pot multi-component reaction of aldehyde derivatives, barbituric acid and 3-methyl-1- phenyl-1H-pyrazol-5(4H)-one in the presence of NHEt2 to afford Michael adduct was carried out. The reaction was carried out in water and afforded new heterocycles in a one-step fashion, with expedient work-up and high yield without extraction and purification steps. The synthesized compounds were evaluated for antimicrobial activity using agar disc diffusion. Molecular docking approach via MOE-Dock program was applied to predict the binding interactions of some of the new pyrazol-barbituric acid derivatives against six different target proteins downloaded from Protein Data Bank.Results: A series of pyrazole-barbituric acid derivatives were successfully synthesized and characterized. The synthesized compounds showed moderate to very good antibacterial activity against S. aureus ATCC 29213 and E. faecalis ATCC29212, as well as also antifungal activity against Candida albicans ATCC 10400Conclusion: A series of pyrazole-barbituric acid derivatives has been synthesized and some of them display antimicrobial activities.Keywords: Pyrazole, Barbituric acid, Pyrazole-barbituric acid derivatives, Antimicrobial activity, Molecular dockin

Cooccurrence of NDM-1, ESBL, RmtC, AAC(6′)-Ib, and QnrB in Clonally Related Klebsiella pneumoniae Isolates Together with Coexistence of CMY-4 and AAC(6′)-Ib in Enterobacter cloacae Isolates from Saudi Arabia

The aim of this study was to investigate the mechanisms responsible for resistance to antimicrobials in a collection of enterobacterial isolates recovered from two hospitals in Saudi Arabia. A total of six strains isolated from different patients showing high resistance to carbapenems was recovered in 2015 from two different hospitals, with four being Klebsiella pneumoniae and two Enterobacter cloacae. All isolates except one K. pneumoniae were resistant to tigecycline, but only one K. pneumoniae was resistant to colistin. All produced a carbapenemase according to the Carba NP test, and all were positive for the EDTA-disk synergy test for detection of MBL. Using PCR followed by sequencing, the four K. pneumoniae isolates produced the carbapenemase NDM-1, while the two E. cloacae isolates produced the carbapenemase VIM-1. Genotyping analysis by Multilocus Sequence Typing (MLST) showed that three out of the four K. pneumoniae isolates were clonally related. They had been recovered from the same hospital and belonged to Sequence Type (ST) ST152. In contrast, the fourth K. pneumoniae isolate belonged to ST572. Noticeably, the NDM-1-producing K. pneumoniae additionally produced an extended-spectrum ß- lactamase (ESBL) of the CTX-M type, together with OXA-1 and TEM-1. Surprisingly, the three clonally related isolates produced different CTX-M variants, namely, CTX-M- 3, CTX-M-57, and CTX-M-82, and coproduced QnrB, which confers quinolone resistance, and the 16S rRNA methylase RmtC, which confers high resistance to all aminoglycosides. The AAC(6′)-Ib acetyltransferase was detected in both K. pneumoniae and E. cloacae. Mating-out assays using Escherichia coli as recipient were successful for all isolates. The Bla NDM-1 gene was always identified on a 70- kb plasmid, whereas the Bla VIM-1 gene was located on either a 60-kb or a 150-kb plasmid the two E. cloacae isolates, respectively. To the best of our knowledge, this is the first report of the coexistence of an MBL (NDM-1), an ESBL (CTX-M), a 16S rRNA methylase (RmtC), an acetyltransferase (AAC[6′]-Ib), and a quinolone resistance enzyme (QnrB) in K. pneumoniae isolates recovered from different patients during an outbreak in a Saudi Arabian hospital

Characterization of CTX-M ESBLs in Enterobacter cloacae, Escherichia coli and Klebsiella pneumoniae clinical isolates from Cairo, Egypt

<p>Abstract</p> <p>Background</p> <p>A high rate of resistance to 3^rdgeneration cephalosporins among Enterobacteriaceae isolates from Egypt has been previously reported. This study aims to characterize the resistance mechanism (s) to extended spectrum cephalosporins among resistant clinical isolates at a medical institute in Cairo, Egypt.</p> <p>Methods</p> <p>Nonconsecutive <it>Klebsiella pneumoniae </it>(Kp), <it>Enterobacter cloacae </it>(ENT) and <it>Escherichia coli </it>(EC) isolates were obtained from the clinical laboratory at the medical institute. Antibiotic susceptibility was tested by CLSI disk diffusion and ESBL confirmatory tests. MICs were determined using broth microdilution. Isoelectric focusing (IEF) was used to determine the pI values, inhibitor profiles, and cefotaxime (CTX) hydrolysis by the β-lactamases. PCR and sequencing were performed using <it>bla</it>_CTX-Mand IS<it>Ecp1</it>-specific primers, with DNA obtained from the clinical isolates. Conjugation experiments were done to determine the mobility of <it>bla</it>_CTX-M.</p> <p>Results</p> <p>All five clinical isolates were resistant to CTX, and were positive for ESBL screening. IEF revealed multiple β-lactamases produced by each isolate, including a β-lactamase with a pI of 8.0 in Kp and ENT and a β-lactamase with a pI of 9.0 in EC. Both β-lactamases were inhibited by clavulanic acid and hydrolyzed CTX. PCR and sequence analysis identified <it>bla</it>_CTX-M-14in Kp and ENT and a <it>bla</it>_CTX-M-15in EC. Both <it>bla</it>_CTX-M-14and <it>bla</it>_CTX-M-15were preceded by IS<it>Ecp1 </it>elements as revealed by partial sequence analysis of the upstream region of the <it>bla</it>_CTX-Mgenes. <it>bla</it>_CTX-M-15 was transferable but not <it>bla</it>_CTX-M-14.</p> <p>Conclusion</p> <p>This is the first report of CTX-M-14 in Kp and ENT isolates from Egypt, the Middle East and North Africa.</p

Synthesis, Single Crystal X-ray Analysis, and Antifungal Profiling of Certain New Oximino Ethers Bearing Imidazole Nuclei

Fungal infections threaten human health, particularly in immune-compromised patients worldwide. Although there are a large number of antifungal agents available, the desired clinical attributes for the treatment of fungal infections have not yet been achieved. Azoles are the mainstay class of the clinically used antifungal agents. In the current study, the synthesis, spectroscopic characterization, and antifungal activity of certain new oximino ethers Va–n bearing imidazole nuclei are reported. The (E)-configuration of the imine double bond of the synthesized compounds Va–n has been confirmed via single crystal X-ray analysis of compound Vi as a representative example of this class of compounds. The molecular structure of compound Vi was crystallized in the monoclinic, P21/c, a = 18.7879(14) Å, b = 5.8944(4) Å, c = 16.7621(12) Å, β = 93.063(3)°, V = 1855.5(2) Å3, Z = 4. The in vitro antifungal activity of the synthesized compounds Va–n were evaluated using diameter of the inhibition zone (DIZ) and minimum inhibitory concentration (MIC) assays against different fungal strains. Compound Ve manifested anti-Candida albicans activity with an MIC value of 0.050 µmol/mL, being almost equipotent with the reference antifungal drug fluconazole (FLC),while compounds Vi and Vn are the most active congeners against Candida parapsilosis, being equipotent and about twenty-three times more potent than FLC with an MIC value of 0.002 µmol/mL. The results of the current report might support the development of new potent and safer antifungal azoles

Synthesis and Spectroscopic Identification of Certain Imidazole-Semicarbazone Conjugates Bearing Benzodioxole Moieties: New Antifungal Agents

During the last three decades the extent of life-threatening fungal infections has increased remarkably worldwide. Synthesis and structure elucidation of certain imidazole-semicarbazone conjugates 5a&ndash;o are reported. Single crystal X-ray analysis of compound 5e unequivocally confirmed its assigned chemical structure and the (E)-configuration of its imine double bond. Compound 5e crystallized in the triclinic system, P-1, a = 6.3561 (3) &Aring;, b = 12.5095 (8) &Aring;, c = 14.5411 (9) &Aring;, &alpha; = 67.073 (4)&deg;, &beta; = 79.989 (4)&deg;, &gamma; =84.370 (4)&deg;, V = 1048.05 (11) &Aring;3, Z = 2. In addition, DIZ and MIC assays were used to examine the in vitro antifungal activity of the title conjugates 5a&ndash;o against four fungal strains. Compound 5e, bearing a 4-ethoxyphenyl fragment, showed the best MIC value (0.304 &micro;mol/mL) against both C. tropicalis and C. parapsilosis species, while compounds 5c (MIC = 0.311 &micro;mol/mL), 5k, and 5l (MIC = 0.287 &micro;mol/mL) exhibited the best anti-C. albicans activity

Synthesis, and characterization of a new series of sulfite and sulfate derivatives of d-Mannitol

In this work, synthesis and characterization of a series of d-Mannitol derivatives with sulfite 2a–d and sulfate 3a–d moieties have been investigated. The method entails a two-step synthesis. The first step involves the Sharpless-type reaction of DIOL 1a–d with SOCl2 in CH2Cl2 in the presence of Et3N to afford the intermediate sulfite derivatives 2a–d in good yield. The second step includes the oxidation reaction of the resulting intermediate in the presence of NaIO4 in a mixture of CCl4/CH3CN/H2O (3/3/2 ratio) in the presence of catalytic amount of RuCl3·H2O to afford the desired sulfate moiety 3a–d in a moderate to high yield (66–96%). The structures of all newly synthesized compounds have been elucidated by 1H, 13C NMR, GCMS, and IR spectrometry

Fecal Colonization with Extended-Spectrum Beta-Lactamase and AmpC-Producing Escherichia coli

Background. Extended-spectrum β-lactamases (ESβLs) and AmpC β-lactamases cause β-lactam resistance in Escherichia coli. Fecal colonization by ESβL- and/or AmpC-positive E. coli is a source of nosocomial infections. Methods. In order to investigate inpatient fecal colonization by ESβLs and AmpC, antibiotic sensitivity tests were conducted and minimum inhibitory concentrations (MICs) were determined using the disk diffusion method and E-test, respectively. Characterization of ESβL and AmpC was performed using E-test strips, and a set of PCRs and DNA sequence analyses were used to characterize the ESβL and AmpC genes. Results. The whole collection of E. coli isolates (n=50) was sensitive to imipenem, tigecycline, colistin, and fosfomycin, while 26% of the isolates showed reduced susceptibility to ceftazidime (MIC ≥ 4 μg/mL). ESβL was phenotypically identified in 26% (13/50) of cases, while AmpC activity was detected in two ESβL-producing E. coli isolates. All ESβL-producing E. coli were positive for the CTX-M gene, eleven isolates carried blaCTX-M-15, and two isolates carried blaCTX-M-14 gene. Two CTX-M-positive E. coli isolates carried blaCMY-2. Conclusions. The alimentary tract is a significant reservoir for ESβL- and/or AmpC-producing E. coli, which may lead to nosocomial infection

Fecal Colonization with Extended-Spectrum Beta-Lactamase and AmpC-Producing Escherichia coli

Background. Extended-spectrum -lactamases (ES Ls) and AmpC -lactamases cause -lactam resistance in Escherichia coli. Fecal colonization by ES L-and/or AmpC-positive E. coli is a source of nosocomial infections. Methods. In order to investigate inpatient fecal colonization by ES Ls and AmpC, antibiotic sensitivity tests were conducted and minimum inhibitory concentrations (MICs) were determined using the disk diffusion method and E-test, respectively. Characterization of ES L and AmpC was performed using E-test strips, and a set of PCRs and DNA sequence analyses were used to characterize the ES L and AmpC genes. Results. The whole collection of E. coli isolates ( = 50) was sensitive to imipenem, tigecycline, colistin, and fosfomycin, while 26% of the isolates showed reduced susceptibility to ceftazidime (MIC ≥ 4 g/mL). ES L was phenotypically identified in 26% (13/50) of cases, while AmpC activity was detected in two ES L-producing E. coli isolates. All ES L-producing E. coli were positive for the CTX-M gene, eleven isolates carried , and two isolates carried CTX-M-14 gene. Two CTX-M-positive E. coli isolates carried CMY-2 . Conclusions. The alimentary tract is a significant reservoir for ES L-and/or AmpC-producing E. coli, which may lead to nosocomial infection