scholarly journals Synthesis andIn VitroEvaluation of New Thiosemicarbazone Derivatives as Potential Antimicrobial Agents

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Zafer Asım Kaplancıklı ◽  
Mehlika Dilek Altıntop ◽  
Belgin Sever ◽  
Zerrin Cantürk ◽  
Ahmet Özdemir

In an effort to develop potent antimicrobial agents, new thiosemicarbazone derivatives were synthesizedviathe reaction of 4-[4-(trifluoromethyl)phenyl]thiosemicarbazide with aromatic aldehydes. The compounds were evaluated for their inhibitory effects on pathogenic bacteria and yeasts using the CLSI broth microdilution method. Microplate Alamar Blue Assay was also carried out to determine the antimycobacterial activities of the compounds againstMycobacterium tuberculosisH37Rv. Among these derivatives, compounds5and11were more effective againstEnterococcus faecalis(ATCC 29212) than chloramphenicol, whereas compounds1,2, and12and chloramphenicol showed the same level of antibacterial activity againstE. faecalis. Moreover, compound2and chloramphenicol exhibited the same level of antibacterial activity againstStaphylococcus aureus. On the other hand, the most potent anticandidal derivatives were found as compounds2and5. These derivatives and ketoconazole exhibited the same level of antifungal activity againstCandida glabrata. According to the Microplate Alamar Blue Assay, the tested compounds showed weak to moderate antitubercular activity.

2006 ◽  
Vol 1 (11) ◽  
pp. 1934578X0600101 ◽  
Author(s):  
Jürgen Reichling ◽  
Ulrike Suschke ◽  
Jürgen Schneele ◽  
Heinrich Konrad Geiss

A selection of structurally diverse components of essential oils was subjected to an antibacterial screening against the Gram-positive bacteria Staphylococcus aureus and Streptococcus pneumoniae as well as the Gram-negative bacteria Escherichia coli and Haemophilus influenzae using a broth microdilution method. In addition, the irritation potential of these substances to mucous membranes was evaluated by a modified HET-CAM (Hen's Egg Test-Chorioallantoic Membrane) assay. Minimum inhibitory concentrations (MIC) and irritation threshold concentrations (ITC) were compared in order to identify substances with a low mucous membrane irritation potential at the antibacterially effective concentration. Regarding the antibacterial activity, the most active substances were cinnamaldehyde, phenols, monoterpene alcohols and aldehydes. Oxygenated monoterpenes and phenylpropanoids without either alcohol or aldehyde function (ethers, ketones) showed moderate activity. Mono- and sesquiterpene hydrocarbons, as well as sesquiterpene alcohols, were more or less inactive against most of the bacteria tested, with the exception of Streptococcus pneumoniae whose growth was inhibited by sesquiterpenes at exceptionally low concentrations. In most cases, the irritation potential of the test compounds could also be traced back to their structural features. 2-Phenylethanol, monoterpene alcohols, phenols and aromatic aldehydes had the lowest ITC-values, followed by monoterpene aldehydes, ketones and ethers. In contrast, monoterpene hydrocarbons caused irritation only at higher doses. Of special interest was the fact that all the sesquiterpenes tested were not irritant even when applied undiluted to the chorioallantoic membrane (CAM).


Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1059
Author(s):  
Anna Nowaczek ◽  
Marta Dec ◽  
Dagmara Stępień-Pyśniak ◽  
Renata Urban-Chmiel ◽  
Agnieszka Marek ◽  
...  

Wild animals are increasingly reported as carriers of antibiotic-resistant and pathogenic bacteria including Enterobacteriaceae. However, the role of free-living birds as reservoirs for potentially dangerous microbes is not yet thoroughly understood. In our work, we examined Escherichia coli strains from wild birds in Poland in relation to their antimicrobial agents susceptibility, virulence and phylogenetic affiliation. Identification of E. coli was performed using MALDI-TOF mass spectrometry. The antibiotic susceptibility of the isolates was determined by the broth microdilution method, and resistance and virulence genes were detected by PCR. E. coli bacteria were isolated from 32 of 34 samples. The strains were most often classified into phylogenetic groups B1 (50%) and A (25%). Resistance to tetracycline (50%), ciprofloxacin (46.8%), gentamicin (34.3%) and ampicillin (28.1%) was most frequently reported, and as many as 31.2% of E. coli isolates exhibited a multidrug resistance phenotype. Among resistance genes, sul2 (31.2% of isolates) and blaTEM (28.1%) were identified most frequently, while irp-2 (31.2%) and ompT (28.1%) were the most common virulence-associated genes. Five strains were included in the APEC group. The study indicates that wild birds can be carriers of potentially dangerous E. coli strains and vectors for the spread of resistant bacteria and resistance determinants in the environment.


2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Yasser Shahbazi

The aim of the present study was to investigate chemical composition and antibacterial activity of essential oil from the leaf ofMentha spicataplant against common food-borne pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Listeria monocytogenes, Salmonella typhimurium, andEscherichia coliO157:H7). Chemical composition of the essential oil was identified by gas chromatography coupled with mass spectrometer detector (GC-MS). The antibacterial activity of the essential oil was evaluated by broth microdilution method and agar disk diffusion assay. According to the result of GC-MS analysis, 18 components were identified, accounting for 99.89% of the whole essential oil. The main components were carvone (78.76%), limonene (11.50%),β-bourbonene (11.23%),cis-dihydrocarveol (1.43%),trans-caryophyllene (1.04%), menthone (1.01%), menthol (1%), and terpinen-4-ol (0.99). The essential oil exhibited moderate level of antibacterial activity against all test microorganisms. In general, Gram-positive bacteria were more susceptible toM. spicataessential oil than Gram-negative bacteria.L. monocytogeneswas the most sensitive of the microorganisms to the antibacterial activity ofM. spicataessential oil (inhibition zone = 22 mm and MIC and MBC = 2.5 µL/mL). Based on our results, the essential oil ofM. spicataplant collected from Kermanshah province, west of Iran, has a potential to be applied as antibacterial agent.


2011 ◽  
Vol 56 (3) ◽  
pp. 1247-1252 ◽  
Author(s):  
James A. Karlowsky ◽  
Andrew J. Walkty ◽  
Heather J. Adam ◽  
Melanie R. Baxter ◽  
Daryl J. Hoban ◽  
...  

ABSTRACTClinical isolates of theBacteroides fragilisgroup (n= 387) were collected from patients attending nine Canadian hospitals in 2010-2011 and tested for susceptibility to 10 antimicrobial agents using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method.B. fragilis(59.9%),Bacteroides ovatus(16.3%), andBacteroides thetaiotaomicron(12.7%) accounted for ∼90% of isolates collected. Overall rates of percent susceptibility were as follows: 99.7%, metronidazole; 99.5%, piperacillin-tazobactam; 99.2%, imipenem; 97.7%, ertapenem; 92.0%, doripenem; 87.3%, amoxicillin-clavulanate; 80.9%, tigecycline; 65.9%, cefoxitin; 55.6%, moxifloxacin; and 52.2%, clindamycin. Percent susceptibility to cefoxitin, clindamycin, and moxifloxacin was lowest forB. thetaiotaomicron(n= 49, 24.5%),Parabacteroides distasonis/P. merdae(n= 11, 9.1%), andB. ovatus(n= 63, 31.8%), respectively. One isolate (B. thetaiotaomicron) was resistant to metronidazole, and two isolates (bothB. fragilis) were resistant to both piperacillin-tazobactam and imipenem. Since the last published surveillance study describing Canadian isolates ofB. fragilisgroup almost 20 years ago (A.-M. Bourgault et al., Antimicrob. Agents Chemother. 36:343–347, 1992), rates of resistance have increased for amoxicillin-clavulanate, from 0.8% (1992) to 6.2% (2010-2011), and for clindamycin, from 9% (1992) to 34.1% (2010-2011).


Antibiotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 98 ◽  
Author(s):  
Eunice Mgbeahuruike ◽  
Pia Fyhrquist ◽  
Heikki Vuorela ◽  
Riitta Julkunen-Tiitto ◽  
Yvonne Holm

Piper guineense is a food and medicinal plant commonly used to treat infectious diseases in West-African traditional medicine. In a bid to identify new antibacterial compounds due to bacterial resistance to antibiotics, twelve extracts of P. guineense fruits and leaves, obtained by sequential extraction, as well as the piperine and piperlongumine commercial compounds were evaluated for antibacterial activity against human pathogenic bacteria. HPLC-DAD and UHPLC/Q-TOF MS analysis were conducted to characterize and identify the compounds present in the extracts with promising antibacterial activity. The extracts, with the exception of the hot water decoctions and macerations, contained piperamide alkaloids as their main constituents. Piperine, dihydropiperine, piperylin, dihydropiperylin or piperlonguminine, dihydropiperlonguminine, wisanine, dihydrowisanine and derivatives of piperine and piperidine were identified in a hexane extract of the leaf. In addition, some new piperamide alkaloids were identified, such as a piperine and a piperidine alkaloid derivative and two unknown piperamide alkaloids. To the best of our knowledge, there are no piperamides reported in the literature with similar UVλ absorption maxima and masses. A piperamide alkaloid-rich hexane leaf extract recorded the lowest MIC of 19 µg/mL against Sarcina sp. and gave promising growth inhibitory effects against S. aureus and E. aerogenes as well, inhibiting the growth of both bacteria with a MIC of 78 µg/mL. Moreover, this is the first report of the antibacterial activity of P. guineense extracts against Sarcina sp. and E. aerogenes. Marked growth inhibition was also obtained for chloroform extracts of the leaves and fruits against P. aeruginosa with a MIC value of 78 µg/mL. Piperine and piperlongumine were active against E. aerogenes, S. aureus, E. coli, S. enterica, P. mirabilis and B. cereus with MIC values ranging from 39–1250 µg/mL. Notably, the water extracts, which were almost devoid of piperamide alkaloids, were not active against the bacterial strains. Our results demonstrate that P. guineense contains antibacterial alkaloids that could be relevant for the discovery of new natural antibiotics.


2021 ◽  
Vol 17 ◽  
Author(s):  
Lijuan Zhai ◽  
Lili He ◽  
Yuanbai Liu ◽  
Ko Ko Myo ◽  
Zafar Iqbal ◽  
...  

Background: Mononcyclic β-lactams are regarded as the most resistant class of β-lactams against a series of β-lactamases though possess limited antibacterial activity. Aztreonam being the first clinically approved monobactam needs broad-spectrum efficacy through structural modification. Objective: We strive to synthesize a number of monocyclic β-lactams by varying the substituents at N1, C3 and C4 positions of azetidinone ring and study the antimicrobial effect on variable bacterial strains. Methods: Seven new monobactam derivatives 23a-g, containing substituted-amidine moieties linked to the azetidinone ring via thiazole linker, were synthesized through multistep synthesis. The final compounds were investigated for their in vitro antibacterial activities using broth microdilution method, against ten bacterial strains of clinical interest. The minimum inhibitory concentrations (MICs) of newly synthesized derivatives were compared with aztreonam, ceftazidime and meropenem, existing clinical antibiotics. Results: All compounds 23a-g showed higher antibacterial activities (MIC 0.25 µg/mL to 64 µg/mL) against tested strains as compared to aztreonam (MIC 16 µg/mL to >64 µg/mL) and ceftazidime (MIC >64 µg/mL). However all compounds, except 23d, exhibited lower antibacterial activity against all tested bacterial strains as compared to meropenem. Conclusion: Compound 23d showed comparable or improved antibacterial activity (MIC 0.25 µg/mL to 2 µg/mL) to meropenem (MIC 1 µg/mL to 2 µg/mL) in case of seven bacterial species. Therefore, compound 23d may be valuable lead target for further investigations against multi-drug resistant Gram-negative bacteria.


2020 ◽  
Author(s):  
Baoguang Liu ◽  
Xiaoling Yuan ◽  
Yiheng Chen ◽  
Xiaoshen Li ◽  
Ming Bai ◽  
...  

Abstract Background The spread of ESBLs-producing bacteria has been strikingly rapid in many regions of the world and it causes therapeutic difficulties in everyday practice. The aims of this study were to investigate the prevalence and susceptibilities of ESBLs-producing Escherichia coli isolates from healthy Tibetan yaks in China, to evaluate the activity of drug combinations on ESBLs-producing E. coli isolates. Methods From July 2018 to August 2019, a total of 750 nasal swab samples were tested for the presence of E. coli and ESBLs-producing strains. The MICs of 11 antimicrobial agents alone and combinations with sulbactam, EDTA or sulbactam-EDTA against 240 ESBLs-producing E.coli strains were determined by the broth microdilution method. Results Overall, 59.87% (n = 449) of the samples were positive for E. coli, 240 (53.45%) of 449 E. coli isolates were confirmed to be ESBLs-producing. The addition of sulbactam to the third generation cephalosporins, amikacin and fosfomycin for all isolates resulted in low MICs, increasing the level of susceptibility from 0, 0 and 0% to 50 ~ 87.5, 4.2 and 100% respectively. The addition of EDTA to fluoroquinolones, doxycycline, florfenicol, amikacin and fosfomycin, showed improved activities and resulted in low MICs, increasing the level of susceptibility from 0, 0, 8.3, 0 and 0% to 4.2 ~ 29.2, 33.3, 33.3, 66.7 and 45.8%, respectively. All other antibacterials (except fluoroquinolones, doxycycline and florfenicol), when combined with sulbactam-EDTA, were found to be more active than combinations only with sulbactam or with EDTA against most of isolates, with lower MIC50s and MIC90s. Conclusion In conclusion, ESBLs-producing E. coli isolates were widespread in healthy Tibetan yaks in China. ESBLs-producing E. coli isolates exhibited varying degrees of multidrug resistance. This study these findings suggested that sulbactam can enhance activity of β-lactams and some non-β-lactams of antimicrobial agents and had a synergistic effects with EDTA in improving activities of some families of antimicrobials.


2007 ◽  
Vol 70 (3) ◽  
pp. 736-738 ◽  
Author(s):  
M. NORSTRÖM ◽  
G. JOHNSEN ◽  
M. HOFSHAGEN ◽  
H. THARALDSEN ◽  
H. KRUSE

Antimicrobial susceptibility in Campylobacter jejuni collected from the environment outside four broiler houses (n = 63) and from the environment inside these broiler houses (including broiler droppings) (n = 36) from May to September 2004 was studied and compared with isolates from Norwegian broilers analyzed within the frame of the Norwegian monitoring program of antimicrobial resistance in feed, food, and animals (NORM-VET) in 2004 (n = 75). The MICs of oxytetracycline, ampicillin, erythromycin, gentamicin, enrofloxacin, and nalidixic acid were obtained by the broth microdilution method VetMIC. The present study, which to our knowledge is the first Norwegian study on the occurrence of antimicrobial resistance in Campylobacter spp. from the environment of broiler houses, revealed a very low occurrence of antimicrobial resistance in C. jejuni from the broilers and broiler house environments studied. All isolates originating from the four broiler houses studied were susceptible to all the antimicrobial agents tested, except for one isolate from the outdoor environment (courtyard soil), which was resistant to oxytetracycline (MIC, 8 mg/liter). For the isolates from broilers (NORM-VET), low prevalences of resistance to oxytetracycline (1.3%) and ampicillin (4%) were observed. No quinolone resistance was observed. The results for the broiler isolates are in agreement with the earlier findings of a very low prevalence of resistance in Campylobacter from broilers in Norway, which reflects the low usage of antimicrobials in Norwegian broiler production. Furthermore, the present data are in accordance with antimicrobial susceptibility data for C. jejuni from domestically acquired human cases.


2020 ◽  
Vol 75 (10) ◽  
pp. 2907-2913 ◽  
Author(s):  
Helio S Sader ◽  
Cecilia G Carvalhaes ◽  
Leonard R Duncan ◽  
Robert K Flamm ◽  
Dee Shortridge

Abstract Background The Program to Assess Ceftolozane/Tazobactam Susceptibility (PACTS) monitors the in vitro activity of ceftolozane/tazobactam and numerous antimicrobial agents against Gram-negative bacteria worldwide. Objectives To evaluate the activity of ceftolozane/tazobactam and resistance trends among Pseudomonas aeruginosa and Enterobacterales isolates in Europe between 2012 and 2018. Methods P. aeruginosa (7503) and Enterobacterales (30 582) isolates were collected from 53 medical centres in 26 countries in Europe and the Mediterranean region and tested for susceptibility by reference broth microdilution method in a central laboratory. MIC results were interpreted using EUCAST criteria. Results Ceftolozane/tazobactam was the most active compound tested against P. aeruginosa isolates after colistin, with overall susceptibility rates of 94.1% in Western Europe and 80.9% in Eastern Europe. Moreover, ceftolozane/tazobactam retained activity against 75.2% and 59.2% of meropenem-non-susceptible P. aeruginosa isolates in Western and Eastern Europe, respectively. Tobramycin was the third most active compound tested against P. aeruginosa, with susceptibility rates of 88.6% and 70.9% in Western and Eastern Europe, respectively. Ceftolozane/tazobactam was active against 94.5% of all Enterobacterales and 96.1% of meropenem-susceptible isolates from Western Europe. In Eastern Europe, ceftolozane/tazobactam was active against 79.4% of Enterobacterales overall and 86.2% of meropenem-susceptible isolates. Discussion Antimicrobial susceptibility rates for agents commonly used to treat serious systemic infections varied widely among nations and geographic regions and were generally lower in Eastern Europe compared with Western Europe. Ceftolozane/tazobactam demonstrated potent activity against P. aeruginosa, including MDR strains, and retained activity against most meropenem-susceptible Enterobacterales causing infection in European medical centres.


2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Ian Morrissey ◽  
Stephen Hawser ◽  
Sibylle H. Lob ◽  
James A. Karlowsky ◽  
Matteo Bassetti ◽  
...  

ABSTRACT Eravacycline is a novel, fully synthetic fluorocycline antibiotic being developed for the treatment of serious infections, including those caused by resistant Gram-positive pathogens. Here, we evaluated the in vitro activities of eravacycline and comparator antimicrobial agents against a recent global collection of frequently encountered clinical isolates of Gram-positive bacteria. The CLSI broth microdilution method was used to determine in vitro MIC data for isolates of Enterococcus spp. (n = 2,807), Staphylococcus spp. (n = 4,331), and Streptococcus spp. (n = 3,373) isolated primarily from respiratory, intra-abdominal, urinary, and skin specimens by clinical laboratories in 37 countries on three continents from 2013 to 2017. Susceptibilities were interpreted using both CLSI and EUCAST breakpoints. There were no substantive differences (a >1-doubling-dilution increase or decrease) in eravacycline MIC90 values for different species/organism groups over time or by region. Eravacycline showed MIC50 and MIC90 results of 0.06 and 0.12 μg/ml, respectively, when tested against Staphylococcus aureus, regardless of methicillin susceptibility. The MIC90 values of eravacycline for Staphylococcus epidermidis and Staphylococcus haemolyticus were equal (0.5 μg/ml). The eravacycline MIC90s for Enterococcus faecalis and Enterococcus faecium were 0.06 μg/ml and were within 1 doubling dilution regardless of the vancomycin susceptibility profile. Eravacycline exhibited MIC90 results of ≤0.06 μg/ml when tested against Streptococcus pneumoniae and beta-hemolytic and viridans group streptococcal isolates. In this surveillance study, eravacycline demonstrated potent in vitro activity against frequently isolated clinical isolates of Gram-positive bacteria (Enterococcus, Staphylococcus, and Streptococcus spp.), including isolates collected over a 5-year period (2013 to 2017), underscoring its potential benefit in the treatment of infections caused by common Gram-positive pathogens.


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