American Type Culture Collection Strains Research Articles

ISOLATION, CHARACTERIZATION AND ANTIMYCOBACTERIAL POTENCY OF A FURAN DERIVATIVE FROM THE CHLOROFORM CRUDE EXTRACT OF Icacina trichantha oliv TUBER.

Spectroscopic analysis of a pure isolate (OAU 2, a furan derivative) by column chromatography from the chloroform crude extract of Icacina trichantha tuber was done using FT-IR, 1HNMR, 13CNMR, COSY and was established by literature as well as the investigation of antimycobacterial potency. This anitmycobacterial activity revealed that this isolate actually has activity against DR-TB Strain and H37RV Strain which are American type culture collection strain and multi-drug resistant strains of M. tuberculosis being the test organisms. Hence, confirming the folk believe of the use of I. trichantha tuber in the treatment of “serious cough”

Disinfection Ability of Aqueous Ocimum sanctum (Tulsi) Extract against Candida albicans and Staphylococcus aureus Inoculated on Maxillofacial Silicone - An In Vitro Study

Abstract Background: Patients who use maxillofacial prostheses often encounter difficulties cleaning them thoroughly daily. Traditional cleaning methods may not work and could change the prostheses’ physical properties. Therefore, it is essential to look for alternative disinfection methods. Aim: The aim of this study was to evaluate the efficacy of aqueous extract of Ocimum sanctum (tulsi) against Candida albicans and Staphylococcus aureus inoculated on maxillofacial silicone. Materials and Methods: One hundred and twenty silicone discs, 5 mm diameter, 2 mm thick, were made with maxillofacial Factor II A-2000. Samples were divided into four main groups, each with three subgroups of 10 samples. Each subset was inoculated with C. albicans, S. aureus clinical strains, and the American Type Culture Collection (ATCC) strains. The specimens were incubated at 37°C for 72 h and then soaked in three disinfectant solutions: a neutral soap solution for 30 s, 0.2% chlorhexidine for 10 min, and aqueous tulsi for 10 min. The disinfection ability was determined based on the number of surviving cells by methoxy-nitro-sulfophenyl-tetrazolium carboxanilide assay, and the results were analyzed using a one-way analysis of variance and the post hoc Tukey’s test. Results: There were no significant differences in the ability to disinfect between neutral soap, 0.2% chlorhexidine, and tulsi extract when tested against clinical and ATCC C. albicans and clinical S. aureus. The P > 0.05 indicates that the differences between the disinfection abilities were not statistically significant. However, the 0.2% chlorhexidine disinfectant showed better results when used on Staphylococcus ATCC strains, with a P < 0.001. Conclusion: A 10% aqueous extract of tulsi can be used as a disinfectant for clinical and ATCC strains of C. albicans and the clinical strain of S. aureus.

Synthesis and Antibacterial Activity of Mono- and Bi-Cationic Pyridinium 1,2,4-Oxadiazoles and Triazoles.

One of the main causes of mortality in humans continues to be infectious diseases. Scientists are searching for new alternatives due to the fast increase in resistance of some harmful bacteria to the frontline antibiotics. To effectively treat pathogenic infections, it is crucial to design antibiotics that can prevent the development of pathogenic resistance. For this purpose, a set of 39 quaternary pyridinium and bis-pyridinium salts with different lengths of side alkyl or fluorinated chains, heterocyclic spacers, and counter ions were tested on diverse reference bacterial ATCC (American Type Culture Collection) strains, such as S. aureus and E. coli. Subsequently, 6 out of the 39 pyridinium salts showing relevant MIC (Minimum Inhibitory Concentration) values were tested on clinically isolated, resistant strains of S. aureus, S. epidermids, S. haemolyticus, K. pneumoniae, A. baumannii, and P. aeruginosa. Additional tests have been performed to assess if the minimum concentration detected through MIC assay may limit the growth of biofilms.

Antibacterial activity of biosynthesized zinc oxide nanoparticles using Kombucha extract

Antibacterial resistance is a growing global vital medical problem when the innovation and development of new antibiotics are dwindling. Different nanomaterials were synthesized and developed as safe and effective alternative antimicrobial agents. The current study highlights the effect of the antibacterial activity of newly biosynthesized zinc oxide nanoparticles (ZnO NPs) obtained from Kombucha extract. Production of ZnO NPs was optimized and the synthesized nanoparticles were characterized using UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential and transmission electron microscope (TEM) analysis. The optimum conditions for ZnO NPs production were at temperature 30 °C, pH 9 and 25 mM of Zn(NO3)2.6H2O. The ZnO NPs biosynthesis was detected in the extract within 24 h. at 35 °C in dark conditions. The XRD pattern displayed 100, 101, 110, and 103 crystal planes. FTIR spectrum showed bands of 1° and 2° amines at 2922.6 cm−1 and a stretching vibration band of vinyl at 1657.5 cm−1. In addition, the results confirmed the positive charge (19 ± 3 mV) and crystalline nature of spherical-shaped ZnO NPs with an average size of 23 ± 1.5 nm. The antibacterial activity of ZnO NPs was tested against different American-type culture collection strains. ZnO NPs exhibited minimum inhibition concentration (MIC) values of 25 µg/ml against Escherichia coli ATCC25922, 30 µg/ml against Staphylococcus aureus ATCC25923 and Pseudomonas aeruginosa ATCC27853, 35 µg/ml against Serratia liquefaciens OQ071699.1 and S. saprophyticus OQ071703.1 and 40 µg/ml against Lysinibacillus fusiformis OQ071701.1 and Klebsiella pneumoniae ATCC33495. Ultrastructure TEM study of the treated bacteria by MIC of ZnO NPs confirmed their highly toxic action on the bacterial cell wall, resulting in bacterial cell membrane rupture. Treated bacteria appeared as extensively damaged cells with the formation of vacuoles and lipids. The provided approach of ZnO NPs in combination with Kombucha SCOBY has a promising future in overcoming bacterial resistance problems in place of using antibiotics.

Sprayable Thermoset Nanocomposite Coatings Based on Silanized‐PEG/ZnO to Prevent Microbial Infections of Titanium Implants

AbstractPost‐surgery microbial infections are still one of the main reasons for implant failure, which results in very high physical and psychological pain for the patient and an increased cost for the healthcare system. A polymer nanocomposite antibacterial coating on titanium implants represents a valuable alternative to the more expensive and energy‐consuming technological solutions nowadays used. In this regard, a sprayable thermoset nanocomposite composed of silanized‐terminals polyethylene glycol (PEG)/ZnO nanoparticle is herein proposed. Initially, PEG's terminals' solvent‐free silanization and curing are studied by Fourier Transform Infrared and µRaman spectroscopies. Scanning Electron Microscope investigations and scratch tests have shown that the spraying procedure optimization and the oxidation treatment of the titanium substrate lead to a homogeneous coverage and improved adhesion of the coatings. The antibacterial activity is tested against not only both S. aureus and P. aeruginosa bacterial American Type Culture Collection strains, but also using very aggressive antibiotic‐resistant clinical strains. Interestingly, antibacterial activity, evaluated by time‐killing tests, is observed for all tested bacterial strains. Live/dead tests further confirm that 5 wt% of ZnO allows obtaining a bacteriostatic activity within 24 h, whereas a complete growth inhibition (bactericidal activity) of both tested strains is observed for coatings with 20 wt% of ZnO nanoparticles.

Action of Ethanolic Extract of Holerrhena pubescens on Bacterial Strains

The need to screen efficient, safe, affordable, and readily available antimicrobial agents from various medicinal plants, for their potential antimicrobial activity has become critical in light of the rapid development of microbial resistance against chemotherapeutic drugs (mainly antibiotics). Despite notable advances in the biological and phytochemical evaluation in recent years, comprehensive reviews of Holarrhena pubescens are limited. The main objective of this study is to evaluate the antimicrobial activities of this plant extract. One significant use of plant extracts can be in treating bacterial infections and develop potential antibacterial agents against multi drug resistant (MDR) and susceptible bacteria. If antimicrobial activities are present, these extracts will provide useful information for discovering new compounds with better activity and more effectiveness against resistant and susceptible bacteria responsible for infections than currently available. The ethanolic extract of leaves of Holarrhena pubescens was prepared and tested against multidrug resistant (MDR) and American type culture collection strains of bacteria. We have obtained two types of results in this experiment. The extract showed antimicrobial properties against Staphylococcus aureus (ATCC 23235), Escherichia coli (MDR) and Acinetobacter (MDR), while, it showed no antimicrobial activities along with some growth promoting role against Escherichia coli (ATCC 25922), and Klebsialla pneumoniae (MDR), which may be due to chemicals other than secondary metabolites.

Antifungal Properties of Ethanolic Extract of Holarrhena Pubescens against Candida Species

Antimicrobial resistance is a global problem that jeopardizes the efficient use of modern medicine and the state of the world's health. The effectiveness of traditional antifungals used to treat fungal infections has declined, increasing mortality. Following exposure to antifungal medications, acquired mechanisms can lead to the development of resistance to currently available antifungal medicines. Invasive fungal infections have few treatment choices, and patients who are most at risk frequently have other co-morbid conditions, such as immunosuppression. This problem is made worse by the paucity of novel antifungals now under research. One potential research avenue for tackling the problem of MDR fungal pathogens is plants that are used in traditional medicine. When used to treat infectious diseases, antimicrobials derived from plants have a great deal of therapeutic promise and have less adverse effects than their synthetic counterparts. In this study, the possible antifungal action of ethanolic extract of Holarrhena pubescens was tested against American Type Culture Collection (ATCC) and Multidrug resistant (MDR) strains of pathogenic fungi, Candida species. Antifungal activities of ethanolic extract of Holarrhena pubescens were studied by determining the minimum inhibitory concentration (MIC) value which was done by serial dilution in Mueller Hinton broth.The ethanolic extract of Holarrhena pubescensshowedantifungal activities exhibiting MIC values varying between 1.5625-3.125 mg/mL in both ATCC and MDR fungal pathogenic strains of Candida. Ethanolic extract of Holarrhena pubescenswas found to have effective antifungal activity against Candida species andcould be the cure to invasive candidiasis which is a global health threat.

Structural displacement model of chitooligosaccharide transport through chitoporin

VhChiP is a chitooligosaccharide-specific porin identified in the outer membrane of Vibrio campbellii type strain American Type Culture Collection BAA 1116. VhChiP contains three identical subunits, and in each subunit, the 19-amino acid N-terminal segment serves as a molecular plug (the "N-plug") that controls the closed/open dynamics of the neighboring pores. In this study, the crystal structures of VhChiP lacking the N-plug were determined in the absence and presence of chitohexaose. Binding studies of sugar-ligand interactions by single-channel recordings and isothermal microcalorimetry experiments suggested that the deletion of the N-plug peptide significantly weakened the sugar-binding affinity due to the loss of hydrogen bonds around the central affinity sites. Steered molecular dynamic simulations revealed that the movement of the sugar chain along the sugar passage triggered the ejection of the N-plug, while the H-bonds transiently formed between the reducing end GlcNAc units of the sugar chain with the N-plug peptide may help to facilitate sugar translocation. The findings enable us to propose the structural displacement model, which enables us to understand the molecular basis of chitooligosaccharide uptake by marine Vibrio bacteria.

Antibacterial activity and phytochemical components of leaf extract of Calpurnia aurea

Local Ethiopians use Calpurnia aurea to treat skin infections. However, there is no adequate scientific confirmation. The aim of this study was to evaluate the antibacterial activities of the crude and the fractionated extracts of C. aurea leaves against different bacterial strains. The crude extract was made by maceration. The Soxhlet extraction method was used to obtain fractional extracts. The antibacterial activity against gram positive and gram negative American Type Culture Collection (ATCC) strains was performed using the agar diffusion technique. The minimum inhibitory concentration was determined through the microtiter broth dilution method. Preliminary phytochemical screening was done using standard techniques. The largest yield was obtained from ethanol fractional extract. Except for chloroform, which provided a relatively low yield when compared to petroleum ether, increasing the polarity of the extracting solvent improved the yield. The crude extract, solvent fractions, and the positive control showed inhibitory zone diameter, while the negative control did not. When used at a concentration of 75 mg/ml, the crude extract had similar antibacterial effects as gentamicin (0.1 mg/ml) and the ethanol fraction. The 2.5 mg/ml crude ethanol extract of C. aurea suppressed the growth of Pseudomonas aeruginosa, Streptococcus pneumoniae, and Staphylococcus aureus, according to the MIC values. The extract of C. aurea was more effective in inhibiting P. aeruginosa than the other gram-negative bacteria. Fractionation enhanced the antibacterial effect of the extract. All fractionated extracts showed the highest inhibition zone diameter against S. aureus. Petroleum ether extract had the greatest inhibition zone diameter against all bacterial strains. The non-polar components were more active compared to the more polar fractions. The phytochemical components discovered in the leaves of C. aurea included alkaloids, flavonoids, saponins, and tannins. Among these, the tannin content was remarkably high. The current results could provide a rational support for the traditional use of C. aurea to treat skin infections.

Evaluation of the In Vitro Antifungal Activity of Novel Arylsulfonamides against Candida spp.

The antifungal activity of molecules belonging to the arylsulfonamide chemotype has previously been demonstrated. Here, we screened arylsulfonamide-type compounds against a range of Candida spp. and further established the structure-activity relationship based on a "hit compound". A series of four sulfonamide-based compounds, N-(4-sulfamoylbenzyl) biphenyl-4-carboxamide (3), 2,2-diphenyl-N-(4-sulfamoylbenzyl) acetamide (4), N-(4-sulfamoylphenethyl) biphenyl-4-carboxamide (5) and 2,2-diphenyl-N-(4-sulfamoylphenethyl) acetamide (6), were tested against the American Type Culture Collection (ATCC) and clinical strains of C. albicans, C. parapsilosis and C. glabrata. Based on the fungistatic potential of prototype 3, a further subset of compounds, structurally related to hit compound 3, was synthesized and tested: two benzamides (10-11), the related amine 4-[[(4-4-((biphenyl-4-ylmethylamino)methyl) benzenesulfonamide (13) and the corresponding hydrochloride, 13.HCl. Both amine 13 and its hydrochloride salt had fungicidal effects against Candida glabrata strain 33 (MFC of 1.000 mg/mL). An indifferent effect was detected in the association of the compounds with amphotericin B and fluconazole. The cytotoxicity of the active compounds was also evaluated. This data could be useful to develop novel therapeutics for topical use against fungal infections.

Detection of bacteria in dental samples using the Periodic acid-Schiff (PAS) histological stain

The bacterial cell wall mainly consists of glycoproteins and polysaccharides, which could be detected in dental tissue with specific stain protocols. The present study aimed to investigate bacteria stainability in dental histological samples of human teeth by a histochemical method. Eight extracted teeth, because severely decayed, were decalcified, dehydrated, paraffin-embedded, and serially sectioned at 4 µm thickness each. The serial sections were then stained with Periodic acid-Schiff (PAS). Furthermore, SEM analysis was performed on the same slide of one previously histologically investigated tooth to acquire more details on the structures stained by the PAS method obtained from the histological procedures. Afterward, some American Type Culture Collection (ATCC) strains, smeared on glass slides, were stained following the staining method used in histological samples. Stained rod and cocci forms by PAS stain, observed under light microscopy, were predominantly detected inside dentinal tubules and root canal space of histologically examined specimens, suggesting their bacterial origin. Additional SEM analysis on the identical histological stained slide showed the precise nature of these forms (bacteria) and supplemental information regarding their vitality status. In addition, ATCC smeared strain samples showed variable PAS stainability of microorganisms investigated. Due to its properties, the PAS histochemical stain could be a valid and helpful aid for non- or weakly stainable microorganisms in infected tissues to be associated with other methods of investigation.

Whole-genome sequencing of Histophilus somni strains isolated in Russia.

Histophilus somni is a Gram-negative bacterium belonging to the Pasteurellaceae family that can cause bovine histophilosis. Histophilus may act as a commensal or opportunistic bacterial cattle pathogen. Comparing genomes of the pathogenic strain 2336 with the non-pathogenic preputial 129Pt isolate revealed some putative virulence factors. The study of the complete genomes of H. somni strains circulating in Russia has never been conducted before. This study aimed to identify genetic features of the H. somni strains isolated in Russia and evaluate the possibility of using strains for vaccine development. Three strains of H. somni were isolated from different sources. Strain 188-VIEV was isolated from a vaginal swab sample of cattle with endometritis. 532-VIEV and 551-VIEV were cultured from the cryopreserved bull semen samples imported from Canada. Histophilus somni strain ATCC 700025 provided by ATCC (American Type Culture Collection) was also used in the study. DNA extraction was performed using QIAamp DNA Mini Kit (QIAGEN, USA). The whole-genome sequencing of the four strains was performed using Illumina Miseq. The comparison of the resulting sequences with the complete genomes of H. somni 2336 and 129Pt, and detection of the resistance genes and virulence factors, was performed using the ResFinder and Virulence Factor Database web services. The genome size of the samples varied from 1.9 to 2.3 Mb. The number of coding sequences varied from 1795 to 2256. The average sequence density was 90%. The total guanine-cytosine (GC) content was 36.8%-37.2%, which coincided with data previously obtained for H. somni. Three out of four studied strains encoded putative virulence factors such as filamentous hemagglutinin homologs, lipooligosaccharide biosynthesis proteins, and proteins involved in iron transport and utilization. The Ser83Ile substitution was identified in the DNA topoisomerase II (gyrA) in H. somni strains 532-VIEV and 551-VIEV cultured from bull semen which led to resistance to fluoroquinolones. The gene (AAC-6-Ia + APH-2'') encoding a bifunctional aminoglycoside modification enzyme was detected in strain 551-VIEV. Strains with virulence genes identified could be candidates for designing vaccines and potentially represent antigen sources. The results show that antibiotic-resistant H. somni can be spread with semen used for artificial insemination.

Broad-spectrum antifungal activity of Phyllanthus niruri leaves tested against Candida species

Introduction: The emergence of resistant pathogenic microorganisms against conventional antimicrobials has become a global concern. To combat new and re-emerging infectious illnesses, new antimicrobial agents with different chemical structures and novel modes of action are required. Therefore, this study evaluated ethanolic extracts of Phyllanthus niruri for their antimicrobial activities against Candida species isolated from different clinical samples. Materials and Methods: This involved the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for the identification of Candida species. The ethanolic extraction of P. niruri leaves was examined. The agar well diffusion method was used to determine the antifungal activity of the leaf extracts against standard American Type Culture Collection strains as well as clinical isolates of Candida species. Results: Using PCR-RFLP, Candida tropicalis was found to be the most prevalent species of Candida, followed by Candida albicans, Candida glabrata, Candida krusei and Candida parapsilosis. The ethanol extract of P. nirui leaves showed good activity against all the clinical and standard strains of Candida which were comparable to the standard drug fluconazole. The activity of P. niruri against C. albicans was highest followed by C. parapsilosis, C. tropicalis, C. glabrata and C. krusei at a concentration of 100 mg/ml. Conclusion: The findings of this study support the use of P. niruri plant to treat Candida infections, particularly fluconazole-resistant Candida species.

Green synthesized silver nanoparticles using carrot extract exhibited strong antibacterial activity against multidrug resistant bacteria

Antimicrobial resistance is a worldwide problem. Pathogenic microorganisms develop antibiotic resistance as a result of exposure to inappropriate quantity of antibiotics and accumulation of mutations. Bio-friendly nanomaterial scan be developed as antimicrobial agents. Present study aimed to investigate the activity of biosynthesized silver nanoparticles (AgNPs) obtained from carrot extract of three different regions namely Gilgit, Haripur and Sheikhupura from Pakistan, having significant difference in climate and altitude. UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis were carried out for the morphological characterization of synthesized nanoparticles. Analysis of XRD revealed crystalline nature of AgNPs and average size calculated was about 22, 17 and 10 nm from Gilgit, Haripur and Sheikhupura samples respectively. The antibacterial efficacy of AgNPs was carried out against 7 American type culture collection strains of pathogenic bacteria and three macrolide resistant clinical isolates with promising results. Moreover, antioxidant activity indicated maximum DPPH radical scavenging effects as 47 % using a concentration of 250 μg/mL. Hemolysis assays indicated biocompatibility of AgNPs at lower concentration like 7 μg/mL and 15 μg/mL. Comparative analysis of bioactivity from different sites of sampling had indicated minute differences which may be due to the change in altitude, soil texture and other local environmental changes.

Étude in vitro de la cinétique d’élution et de l’activité biologique de la pipéracilline/tazobactam et de la gentamicine dans du ciment osseux acrylique

BackgroundAntibiotics differ in their elution characteristics from bone cement. But no such data is available on piperacillin and tazobactam. Therefore, we performed an in vitro observational study to examine: (1) in-vitro elution characteristics of piperacillin and tazobactam from bone cement, (2) their biological activity using minimum inhibitory concentration and (3) elution characteristics and biological activity when combined with gentamicin in bone cement. HypothesisThe null hypothesis was that piperacillin and tazobactam after elution from bone cement can achieve concentrations higher than minimum inhibitory concentration. Material and methodsForty milligrams bone cement was mixed with the following combination of antibiotics: without any antibiotic (Sample A, Control), 4g/0.50g piperacillin/tazobactam (Sample B), 6g/0.75g piperacillin/tazobactam (Sample C), 8g/1.0g piperacillin/tazobactam (Sample D) and 4g/0.50g piperacillin/tazobactam and 400mg gentamicin (Sample E). Samples were analysed on reverse-phase ultra-high-performance liquid chromatography. Antibacterial activity in the elute were tested against standard ATCC (American Type Culture Collection) strains. ResultsDetectable drug elution for piperacillin and tazobactam was seen till 21 days. Peak drug levels for all formulations were seen at 48hours (140.8 and 297.5μg/ml for Samples B of piperacillin and tazobactam respectively). About 0.83–1.24% of piperacillin and 23.17-29.17% of tazobactam were released from the samples. Gentamicin improved elution of piperacillin and tazobactam: 140.8 vs 919.9μg/ml (p = 0.000) for Samples B and E of piperacillin respectively and 297.5 and 1138.4μg/ml (p = 0.001) for Samples B and E of tazobactam respectively at 2 days. Sample E showed complete inhibition of tested microorganisms, while B sample was microbiologically less active compared to E on day 5. ConclusionsPiperacillin and tazobactam eluted successfully from bone cement and also retained antimicrobial activity after elution. Maximum elution was seen up to day 2 after which it reduced drastically. Antimicrobial action was seen up to 7 days. Level of evidenceIII; comparative study.

Antimicrobial activities of Nardostachys jatamansi extract against multidrug resistant bacterial species

At present, multidrug resistant (MDR) bacteria have become widespread worldwide, leading to high morbidity and mortality rates in bacterial infections. Again, as there is practically no new antimicrobial agent in the pipeline, this will create a threat to humanity for their survival. In this study, we explored the possible antimicrobial action of ethanolic extract of a typical plant of West Bengal, Nardostachys jatamansi, against MDR and American Type Culture Collection (ATCC) strain bacteria. Antimicrobial activities of Nardostachys jatamansi ethanol extract were studied by disc diffusion technique, and then minimum inhibitory concentration (MIC) determination was done by serial dilution in Mueller Hinton broth. Ethanolic extract of Nardostachys jatamansi showed antimicrobial activities with MIC varied between 2.77- 5.82 mg/mL in both MDR and ATCC bacteria. Ethanolic extract of Nardostachys jatamansi is an effective antimicrobial agent on MDR bacteria and may help save the lives of many critically ill patients.

Colistimethate sodium-chitosan hydrogel for treating Gram-negative bacterial wound infections

The drug resistance is higher among Gram-negative bacteria and demands the usage of strong antibiotics which can in turn result in systemic toxicity. In the treatment of the chronic wounds harboring pathogenic Gram-negative bacteria, the demand for an antimicrobial product that can be topically administered has been on the rise. In an effort to address the above issue, we have developed Colistimethate sodium (a high-end antibiotic) loaded chitosan hydrogel and characterized. The prepared hydrogel is very stable and observed to be bio- and hemo-compatible in nature. The antibacterial activity of the prepared hydrogel was studied against both ATCC (American Type Culture Collection) strains and clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. The CMS incorporated hydrogel is also capable of inhibiting the biofilm formation. The developed hydrogel can be potentially being used for the treatment of Gram-negative bacterial infected wounds.

In Vitro Antibacterial Activity of Ethanolic Extract of Neem Leave (Azadirachtaindica Linn) Against Clinical Isolates

Background: Emerging multidrug resistance amongst pathogens is making the choice of antibiotics for the management of infections extremely difficult and threatens the return of the pre-antibiotic era in healthcare settings. To tackle this menace, there is a growing need for exploring bioactive compounds derived from herbal extracts, which could be incorporated as alternative therapeutic agents in the antimicrobial therapy of such infections. Objectives: We evaluated the antibacterial activity of ethanolic extracts of Neem leaves against standard ATCC strains and the pathogens isolated from clinical specimens. Methods: This cross-sectional study was undertaken to assess in vitro antibacterial activity of different concentrations of ethanolic Neem extract against three ATCC (American-type culture collection) strains and 63 clinical isolates using the disk diffusion method. The minimum inhibitory concentration (MIC) of the extract against test isolates was determined by the Broth dilution method. Results: Neem extract exhibited the highest antimicrobial activity toward Escherichia coli ATCC-25922 followed by Staphylococcus aureus ATCC-25923 and Pseudomonas aeruginosa ATCC-27853 strains. Amongst the Gram-positive isolates, the extract exhibited significantly high antibacterial activity against S. aureus and Enterococcus spp. Amongst the Gram-negative isolates, high antibacterial activity was seen against E. coli followed by Klebsiella pneumoniae and Proteus mirabilis. In this study, the lowest MIC values were observed against E. coli followed by S.aureus, P. mirabilis, and K. pneumoniae. The highest MIC values of the extract were observed against non-fermenters, like P. aeruginosa and Acinetobacter spp. isolates. Conclusion: This study strongly depicts that the ethanolic extract of Neem leaves exhibits significant antibacterial activity not only against the standard ATCC strains but also against various clinical isolates

Repositioning of Disulfiram in Association with Vancomycin Against Enterococcus spp. MDR and XDR.

The identification of molecules that exhibit potent antibacterial activity and are capable of circumventing resistance mechanisms is an unmet need. The repositioning of approved drugs is considered an advantageous alternative in this case, and has gained prominence. In addition, drug synergism can reduce morbidity and mortality in the treatment of nosocomial infections caused by multi-drug resistant microorganisms (MDR). Whole cell growth inhibition assays were used to define the in vitro antibacterial activity of disulfiram against two standard American Type Culture Collection (ATCC) strains and 35 clinical isolates of vancomycin-resistant enterococci (VRE). The ability of disulfiram to synergize with vancomycin was determined by fractional inhibitory concentration index, preceded by the checkerboard test. The cytotoxicity of drugs alone and in combination was tested against Raw 264.7 cells. Disulfiram exhibited potent antibacterial activity against VRE (MIC 16-64µgmL-1). Results: Associated with vancomycin, disulfiram it had a reduction in MIC of up to 64 times, with values of 0.5-4µgmL-1. Vancomycin had a MIC of 128-1024µgmL-1; combined, reduced this value by up to 124 times (8µgmL-1), with synergy occurring against all strains. Disulfiram and vancomycin alone and in combination did not show cytotoxicity against the eukaryotic cell line. Based on these results, we suggest that the redirection of disulfiram may be promising in the treatment of infections caused by VRE, since it was able to potentiate the activity of vancomycin against the strains, being able to act as an adjuvant in cases of serious infections caused by Enterococcus.

In vitro study of elution kinetics and biological activity of piperacillin/tazobactam and gentamicin in acrylic bone cement

BackgroundAntibiotics differ in their elution characteristics from bone cement. But no such data is available on piperacillin and tazobactam. Therefore, we performed an in vitro observational study to examine (1) in vitro elution characteristics of piperacillin and tazobactam from bone cement, (2) their biological activity using minimum inhibitory concentration and (3) elution characteristics and biological activity when combined with gentamicin in bone cement. HypothesisThe null hypothesis was that piperacillin and tazobactam after elution from bone cement can achieve concentrations higher than minimum inhibitory concentration. Material and methodsForty milligrams bone cement was mixed with the following combination of antibiotics: without any antibiotic (sample A, control), 4g/0.50g piperacillin/tazobactam (sample B), 6g/0.75g piperacillin/tazobactam (sample C), 8g/1.0g piperacillin/tazobactam (sample D) and 4g/0.50g piperacillin/tazobactam and 400mg gentamicin (sample E). Samples were analysed on reverse-phase ultra-high-performance liquid chromatography. Antibacterial activity in the elute were tested against standard American Type Culture Collection (ATCC) strains. ResultsDetectable drug elution for piperacillin and tazobactam was seen till 21days. Peak drug levels for all formulations were seen at 48hours (140.8 & 297.5μg/mL for samples B of piperacillin and tazobactam respectively). About 0.83–1.24% of piperacillin and 23.17–29.17% of tazobactam were released from the samples. Gentamicin improved elution of piperacillin and tazobactam: 140.8 vs. 919.9μg/mL (p=0.000) for samples B & E of piperacillin respectively and 297.5 & 1138.4μg/mL (p=0.001) for samples B & E of tazobactam respectively at 2days. Sample E showed complete inhibition of tested microorganisms, while B sample was microbiologically less active compared to E on day 5. ConclusionsPiperacillin and tazobactam eluted successfully from bone cement and also retained antimicrobial activity after elution. Maximum elution was seen up to day 2 after which it reduced drastically. Antimicrobial action was seen up to 7days. Level of evidenceIII; comparative study.