Synthesis, properties and photodynamic activities of some zinc(II) phthalocyanines against Escherichia coli and Staphylococcus aureus

5th International Conference on Porphyrins and Phthalocyanines -- JUL 06-11, 2008 -- Moscow, RUSSIAWOS: 000261517000008Two new zinc phthalocyanine derivatives bearing four 3,5-di-tert-butyl-4-hydroxy-phenyl (ZnPc1) and 3,5-dimethylphenoxy (ZnPc2) have been synthesized and proved by elemental analyses and UV-vis, H-1 NMR, FTIR and MALDI-TOF mass spectra as spectroscopic determination. Thermal stabilities of these neutral Zn-phthalocyanines were performed by thermal gravimetric analysis and, significantly, were found stable up to 373 degrees C for ZnPc1 and 550 degrees C for ZnPc2. In addition, the photostability of the sensitizers was quite successful within 240 min. Furthermore, photodynamic therapy has been investigated using these neutral phthalocyanines. Singlet oxygen generation capacities of ZnPc1 and ZnPc2 were studied using 1,3-diphenyl-iso-benzofuran (50.0 mu M) as a selective singlet oxygen trap in DMSO and both of them demonstrated very high singlet oxygen generation capacity. Photodynamic therapy is of considerable interest for its potential its an antimicrobial therapy on the grounds that the photodynamic activity of these compounds was tested against a Gram-negative bacteria, Escherichia coli and a Gram-positive bacteria, Staphylococcus aureus. Suspensions of the microorganisms were irradiated for 240 min in the presence of ZnPc1 (with hydrophilic group) and ZnPc2 phthalocyanines. In order to simulate solar radiation, we used a 750 W xenon lamp. Minimum photosensitizer concentration was used as 0.1 mg.10 mL(-1) in 1% dimethylsulfoxide/phosphate buffer saline solution (DMSO/PBS). Moreover, the photostability of these compounds has been investigated and the effect of the amount of DMSO tested against selected bacteria. In the dark, with and without Pes, bacterial inactivation did not occur. Bacterial inactivation by light with ZnPc1 was observed in response to Gram-negative bacteria E. coli and Gram-positive bacteria S. aureus, whereas the photoinactivation studies with ZnPc2 have revealed that the lack of its activity is due to its poor affinity for either of the organisms. These results suggest that a neutral amphiphilic photosensitizer may be easily used in an application concerning photoinactivation of bacterial cells as well as ionic photosensitizers. Copyright (c) 2008 Society of Porphyrins & Phthalocyanines

Investigation of the presence of carbapenemases in carbapenem-resistant Klebsiella pneumoniae strains by MALDI-TOF MS (matrix-assisted laser desorption ionization-time of flight mass spectrometry) and comparison with real-time PCR method

Purpose: We aimed to develop a new procedure for rapid detection of the carbapenemase activity using MALDI-TOF MS, and to determine the sensitivity and specificity of the method. Also, we aimed to determine the distribution of carbapenemase genes among the K.pneumoniae strains isolated in our hospital using real-time PCR. Method: Between January 2017-February 2019; K. pneumoniae strains(n = 74) isolated from blood culture samples were included. Klebsiella pneumoniae NCTC 13438 was used as a positive control and Escherichia coli ATCC 25922 as a negative control. First, Imipenem, meropenem, and ertapenem MIC values of strains were determined. Then blaKPC, blaOXA- 48, and/or blaNDM genes were investigated with PCR. Carbapenemase activity was investigated in strains with the newly developed method using MALDI-TOF MS. The performance of the new method was evaluated for both the second and fourth hours of the incubation period. Results: While 65 strains were found resistant to tested carbapenems, nine of them were susceptible. Of the 65 resistant strains, 57 had blaOXA-48, 15 had blaNDM, and four had blaKPC genes. BlaOXA- 48 and blaNDM genes were detected together in 11 strains. BlaOXA-48, blaNDM, and blaKPC genes were not detected in any of the susceptible strains. The sensitivity and specificity of MALDI-TOF MS at the second hour were 83.1% and 100%, respectively. At the fourth hour, the sensitivity and specificity of MALDI-TOF MS were 100%. No false-positive results were observed. Conclusion: The sensitivity of the method at the fourth hour was better than the second hour. The false-negative results observed in the second hour disappeared when the incubation period was extended to 4 h. MALDI-TOF MS which is still under development is a fast, cost-effective, promising method for the detection of carbapenemase activity.This research was supported by Ege University Scientific Research Projects (EGE BAP, Ege University, Turkey). Project number: 16-TIP-073.Ege University Scientific Research Projects (EGE BAP, Ege University, Turkey) [16-TIP-073

Quercetin inhibits swarming motility and activates biofilm production of Proteus mirabilis possibly by interacting with central regulators, metabolic status or active pump proteins

WOS: 000465081700008PubMed ID: 30668324Background: Via its virulence factors such as swarm differentiation, biofilm and hemolysin production, urease enzyme, Proteus mirabilis causes urinary tract infections (UTIs), especially in complicated cases. Anti-pathogenic compounds attenuate the virulence of bacteria without showing 'cidal' activity and carry the potential to be used in the prevention and treatment of infectious diseases. Purpose: Search for anti-pathogenic effects of quercetin, which is a widely known and biologically active phytochemical, on Proteus mirabilis was the purpose of this study. In this context, the potential inhibitory activity of quercetin on swarming motility and biofilm production of a wild-type strain, P. mirabilis HI4320, was investigated in both phenotypically and genotypically. Methods: Quercetin's effect on swarming motility was examined on LB agar plates, containing quercetin at various concentrations, by measuring the swarming diameter. The effect on biofilm formation, on the other hand, was analyzed by staining the formed biofilm of the bacterium, exposed to quercetin at various concentrations, with crystal violet and reading spectrophotometrically. Differences in expression levels of selected genes involved in swarming regulation were determined by real-time reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) to evaluate the mechanism of inhibitory action on swarming. Further investigations were carried out repeating swarming assays with the clones that derived from the wild-type strain by a TA system kit for direct one-step cloning and overexpressing the relevant genes. Results: Our study revealed that quercetin inhibited swarming motility while activating biofilm production of P. mirabilis in direct proportion to the dose. Although all selected genes are inhibited in the same manner in liquid medium, and no significant differences could be detected in solid medium as demonstrated by RT-qPCR, experiments repeated with the clones overexpressing flhC (a component of flagellar transcriptional activator), speB (an agmatinase enzyme) and ompF (an outer membrane porin) genes showed that the respective clones could restore swarming, compensating for the inhibitory effect of quercetin. Conclusion: Quercetin's inhibitory effect on P. mirabilis swarming was possibly due to interactions with components of swarming regulators, the genes expressing polyamine coding enzymes that trigger swarm differentiation, or active pump proteins.TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [216S357]This work was supported by TUBITAK (The Scientific and Technological Research Council of Turkey) (Grant number: 216S357). Authors thank Mobley Research Laboratory (Ann Arbor, USA) for supplying the wild-type strain used in the study

IN VITRO ACTIVITY OF LINEZOLID/ERTAPENEM COMBINATION IN RESISTANT GRAM-POSITIVE BACTERIA

WOS: 000263117000006PubMed ID: 19334379The increasing prevalence of vancomycin-resistant enterococcus and methicillin-resistant staphylococcus infections has become a major therapeutic challenge and alternative therapy options are under consideration. In the present study, we aimed to evaluate the in vitro antibacterial activity of linezolid combined with ertapenem against two vancomycin-resistant Enterococcus faecium (VREF), two methicillin-resistant Staphylococcus aureus (MRSA) and two methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from clinical specimens. In vitro activity of linezolid/ertapenem combination at 112 x MIC (minimal Inhibitory Concentration), 1 x MIC and 4 x MIC concentrations for each of the isolates was determined by time-kill curve method. At 1 x MIC and 4 x MIC concentrations, additive effect was detected for MRSA (at 6 and 24 h) and VREF (at 6 h) strains. Synergism was observed between two antibiotics at 4 x MIC concentration against one of the MRSE strains at 6(th) hour. Additive effect was determined at 6(th) and 24(th) hours in this strain at 1 x MIC concentration. No synergism was present in the other MRSE strain but additive interaction was detected at 6 h (1/2 x MIC) and 24 h (1 x MIC). Although these results support the use of linezolid/ertapenem combination in infections caused by resistant gram-positive strains, further in vitro and in vivo studies are necessary

Carbapenemase investigation with rapid phenotypic test (RESIST-4 O.K.N.V) and comparison with PCR in carbapenem-resistant Enterobacterales strains

Background and Objectives: RESIST-4 O.K.N.V. assay is a lateral immunochromatocraphic test for the identification of oxacillinase (OXA)-48-like, Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-beta-lactamase (NDM), and Verona integron-encoded metallo-beta-lactamase (VIM) producing strains. It was aimed to evaluate the performance of the RESIST-4 O.K.N.V. test and to compare it with the reference method polymerase chain reaction (PCR). Also, the objective was to determine the distribution of carbapenemase types of CRE strains isolated in our hospital. Materials and Methods: Between January 2016-October 2019, 187 strains isolated from clinical samples were included in this study. Bacterial identification was done using MALDI-TOF MS. Antibiotic susceptibility tests were studied with the VITEK-2 automated system. Meropenem minimum inhibitory concentrations (MICs) were determined by the gradient test. All strains were studied with the RESIST-4 O.K.N.V. test and then the strains were selected for the PCR test. bla(OXA-48), bla(NDM), bla(KPC), and bla(VIM) were investigated with PCR. K. pneumoniae NCTC (R) 13438 (KWIKSTIKTM, Microbiologics (R),USA) was used as the positive control, E. coli ATTC (R) 25922 TM (Microbiologics (R),USA) and three carbapenem-sensitive clinical isolates were also used as the negative control. Results: Meropenem MIC50 and MIC90 values were determined to be >32 mg/ L. With PCR bla(OXA-48), bla(NDM), bla(KPC) and bla(VIM) were detected in 79, 63, 20, and 4 strains, respectively. bla(OXA-48) and bla(NDM) were found together in 51 of the isolates. bla(OXA-48), bla(NDM), bla(KPC), and bla(VIM) were not detected in two strains with carbapenem resistance in susceptibility tests. The sensitivity of the immunochromatographic test was 100% for OXA-48, KPC, and VIM but 84.1% for NDM. Specificity was determined as 100% for OXA-48, NDM, KPC, and VIM. Conclusion: RESIST-4 O.K.N.V. test showed high sensitivity and specificity in detecting OXA-48, KPC, NDM, and VIM type carbapenemases. However, it should be kept in mind that there may be false-negative results related to NDM

Secondary bacterial infections and antimicrobial resistance in COVID-19: comparative evaluation of pre-pandemic and pandemic-era, a retrospective single center study

Purpose In this study, we aimed to evaluate the epidemiology and antimicrobial resistance (AMR) patterns of bacterial pathogens in COVID-19 patients and to compare the results with control groups from the pre-pandemic and pandemic era. Methods Microbiological database records of all the COVID-19 diagnosed patients in the Ege University Hospital between March 15, 2020, and June 15, 2020, evaluated retrospectively. Patients who acquired secondary bacterial infections (SBIs) and bacterial co-infections were analyzed. Etiology and AMR data of the bacterial infections were collected. Results were also compared to control groups from pre-pandemic and pandemic era data. Results In total, 4859 positive culture results from 3532 patients were analyzed. Fifty-two (3.59%) patients had 78 SBIs and 38 (2.62%) patients had 45 bacterial co-infections among 1447 COVID-19 patients. 22/85 (25.88%) patients died who had bacterial infections. The respiratory culture-positive sample rate was 39.02% among all culture-positive samples in the COVID-19 group. There was a significant decrease in extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales (8.94%) compared to samples from the pre-pandemic (20.76%) and pandemic era (20.74%) (p = 0.001 for both comparisons). Interestingly, Acinetobacter baumannii was the main pathogen in the respiratory infections of COVID-19 patients (9.76%) and the rate was significantly higher than pre-pandemic (3.49%, p < 0.002) and pandemic era control groups (3.11%, p < 0.001). Conclusion Due to the low frequency of SBIs reported during the ongoing pandemic, a more careful and targeted antimicrobial prescription should be taken. While patients with COVID-19 had lower levels of ESBL-producing Enterobacterales, the frequency of multidrug-resistant (MDR) A. baumannii is higher.Karolinska InstituteOpen access funding provided by Karolinska Institute. The author(s) received no specific funding for this work