Agar Disk Diffusion Test Research Articles

Antibacterial activity and shear bond strength of fiber-reinforced composites and bonding agents containing 0.5%, 1%, 2.5%, and 5% silver nanoparticles.

Bonded composites may increase bacterial accumulation and caries formation risk. Therefore, assessment of methods to decrease bacterial activity around them would be valuable. The literature on the efficacy of adding silver nanoparticles to fiber-reinforced composite (FRC) or adding them to bonding agents in terms of their antibacterial activity and/or shear bond strength (SBS) is scarce. Thus, we aimed to assess the antibacterial activity of flowable composites and bonding agents containing various percentages of experimental silver nanoparticles (nanosilver) against S. mutans and to evaluate the SBS of FRC and bonding agents containing different amounts of nanosilver to enamel. In this preliminary study, 0% (control), 0.5%, 1%, 2.5%, and 5% nanosilver were added to flowable composite and bonding agent. Syntheses of nanosilver and nanosilver-incorporated composite specimens were approved using X-ray diffraction spectroscopy and scanning electron microscopy. Antibacterial effects of the produced materials on S. mutans were evaluated by colony count with serial dilution method (n = 7 groups × 10 [n = 70] specimens) and agar disc diffusion test (n = 6 groups × 5 [n = 30] composite specimens + n = 6 groups × 5 [n = 30] light-cured bonding + n = 6 groups × 5 [n = 30] uncured bonding) against negative control and cefotaxime antibiotic. Moreover, SBS values of various FRC blocks bonded to enamel using various bonding agents were measured (n = 9 groups × 6 [n = 54] human premolars). Data were analyzed using Kruskal-Wallis, Dunn, two-way analysis of variance, and Tukey's tests (α = 0.05). Composite discs containing all concentrations of nanosilver reduced S. mutans colony counts (P < 0.05); bacterial growth was ceased at samples containing 2.5% and 5% of nanosilver. The reduction in the SBS of FRCs was significant only for 5% nanosilver (P < 0.05). Adding 0.5%, 1%, and 2.5% nanosilver to composite and 0.5% or 1% nanosilver to bonding agent led to a significant antibacterial behavior against S. mutans while not significantly affecting the SBS of FRC.

Antibacterial Activity of Crude Extract and Purified Acetogenins from Annona muricata Seeds

Currently, several biological activities are attributed to the acetogenins (ACGs) of Annonaceae (including Annona muricata); among these is antimicrobial activity. The main focus of this experiment was to evaluate the antimicrobial effect of the crude extract (CE) and purified acetogenins (P-ACGs) from the endosperm of A. muricata seeds using agar disk diffusion, lethality, sub-lethal, and potential damage membrane tests against Gram-positive and Gram-negative microorganisms. According to the results, P-ACGs present the highest antibacterial effect (12.5–4000 µg/mL) against Enterococcus faecalis (11–15.67 mm), Listeria monocytogenes (12–18 mm), Aeromonas hydrophila (10.33–11.67 mm), Bulkholderia cenocepacia (11–12 mm), and Salmonella paratiphy (11–15.67 mm), and a minimum inhibitory concentration ranging from 0.009 to 12.50 µg/mL. Measurement of the membrane potential shows that, in the presence of P-ACGs, the number of viable cells is reduced, with a significant logarithmic reduction observed (0.38, 1.27, and 1.81 CFU/mL) and a significant sub-lethal lesion (57.78, 96.14, and 98.42%) in Escherichia coli, E. faecalis, and L. monocytogenes, respectively. According to this study, the results demonstrate that P-ACGs from A. muricata seeds are potent and effective antibacterial compounds with potential pharmaceutical applications.

Antibiogram of Salmonella isolates from animal and human sources in Southern Taraba, North-East, Nigeria

Salmonella species are responsible for typhoid and paratyphoid fever in humans, as well as gastroenteritis in humans and other animals. Although infections caused by Salmonella are treatable using chemotherapy. Sadly, several antibiotics are now resisted by Salmonella. Hence, this research accessed the antibiogram of a total of 120 Salmonella isolates from food vendors (18.30%) and animal sources (81.7%) in Donga, Ibi, Takum, and Wukari. Isolates were subjected to an Agar disc diffusion test and the following results were produced. On the one hand, 83(84.6%), 73 (74.4%), 79 (80.6%), and 76 (77.6%) of the total 98 Salmonella isolates from animal sources were resistant to Ciprofloxacin, Gentamycin, Tetracycline, and Streptomycin, respectively. Also, all 98 (100%) isolates from this category were resistant to Ampicillin. On the other hand, Chloramphenicol, Gentamycin, Tetracycline, Ampicillin, Ciprofloxacin, and Streptomycin were resisted by 9 (56.3%), 4(25%), 7 (43.8%), 12 (75%) and 5 (31.3%) of the total 16 Non-Typhoidal Salmonella isolates from human sources respectively. 16.7% (1) of the 6 Typhoidal Salmonella isolates from this study were resisted by Augmentin and Streptomycin. Similarly, Chloramphenicol Tetracycline and Ampicillin were all opposed by 66.7% (4) of TS isolates. All isolates showed considerable susceptibility to, Cefotaxime, and Neomycin. Susceptibility and resistant attributes of antimicrobials are consequences to their limited and long-term usage respectively in chemotherapy and food production. Hence regulations should be intensified for antibiotics usage in both animal production and infection management. Also, opportunities for using plant extracts as alternatives to disease management and animal production should be maximized.

Effects of Adding Cinnamon, ZnO, and CuO Nanoparticles on the Antibacterial Properties of a Glass Ionomer Cement as the Luting Agent for Orthodontic Bands and Their Cytotoxicity

This study was conducted to evaluate the effects of adding cinnamon nanoparticles (NPs), Zinc oxide (ZnO) nanoparticles (NPs), and Copper oxide (CuO) NPs on the antibacterial property of a luting and lining glass ionomer cement (GIC) that was used for the cementation of orthodontic bands to the tooth. Cinnamon NPs, ZnO NPs, and CuO NPs were added into a luting and lining GIC in weight percentages of 1%, 2%, and 4%, respectively while a non-modified GIC was considered as the control group. Agar disc diffusion test was applied to assess the antimicrobial property of samples against Streptococcus mutans (S. mutans). The cytotoxicity of the nanoparticles was examined through the MTT assay for gingival fibroblasts. Data showed that GIC containing cinnamon and ZnO NPs displayed a larger inhibition zone diameter and greater antibacterial activity against S. mutans than CuO NPs. Meanwhile, there were no significant differences in the inhibition zone diameter of cinnamon NPs and ZnO NPs. The cytotoxicity assessment revealed the lower cytotoxicity of cinnamon NPs and the higher cytotoxicity of CuO NPs while the cytotoxicity of ZnO NPs was observed to be higher than cinnamon NPs and lower than CuO NPs. GIC containing cinnamon NPs exhibited noticeable antibacterial activity against S. mutans and cinnamon NPs revealed less cytotoxicity and it is can be labeled as a favorable option for further assessment to be applied in fixed orthodontic treatments for the cementation of bands to teeth.

In Vitro Antibacterial Activity of Different Bioceramic Root Canal Sealers

Bioceramic root canal sealers have been introduced in clinical dental use, but less is known about the antibacterial activity against Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguis. The purpose of the study is to compare new bioceramic sealers with a traditional zinc-oxide eugenol material considered as a control. The different bioceramic root canal sealants tested were FillRoot ST, BioRoot™RCS, Well-Root™ PT, and CeraSeal. In vitro antibacterial activity against Streptococci was assessed using the agar disc diffusion test at two different intervals, 24 h and 48 h. A non-parametric statistical analysis was performed to compare the inhibition zones for each of the different materials. Bioceramic root canal sealers showed mild antibacterial activity, while zinc-oxide eugenol-based material showed a stronger inhibition of Streptococci diffusion. No differences were detected for the measurements of inhibition zones between 24 h and 48 h except for FillRoot ST and BioRoot™RCS.

WITHDRAWN: Combination of isothiocyanates and antibiotics increases susceptibility against Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Serratia marcescens

The development and spread of multidrug-resistant organisms (MDRO) is evolving rapidly worldwide. Although effective antibiotics are still available, some infections are difficult to treat. Among MDROs, S. marcescens and A. baumannii are among the difficult-to-treat pathogens causing for instance sepsis and urinary tract infections (UTI). Isothiocyanates (ITC) are natural plant products. The antimicrobial properties of ITC appear to be more effective in combination with some antibiotics. We investigated a mixture of ITC from nature-identical plant extracts of nasturtium and horseradish in different combined concentrations with broad-spectrum antibiotics against S. marcescens, A. baumannii, E. coli, K. pneumoniae and P. mirabilis. First, we investigated the antibacterial activity of the compounds by standard agar disc diffusion test. Next, we evaluated the minimum inhibitory concentrations (MIC) via broth dilution tests. Checkerboard technique was used to assess antimicrobial effects against sulfamethoxazole-trimethoprim, ampicillin-sulbactam, nitrofurantoin, Fosfomycin, ciprofloxacin and imipenem combined with various concentrations of ITC. S. marcescens strains 1-3 showed reversal of resistance at >0.075 μg/mL ITC in combination with nitrofurantoin, whereas 0.05 μg/mL ITC increased antimicrobial susceptibility. Combination of fosfomycin with 0.003 μg/mL ITC resulted in increased efficacy against resistant S. marcescens strains, E. coli, K. pneumoniae and P. mirabilis. Remarkable additive antimicrobial activity was observed at 0.03 μg/mL and 0.06 μg/mL ITC in combination with 0.125 μg/mL imipenem (FIC > 0.5). The combination of ITC and antibiotics is a promising approach for the treatment of UTI caused by MDRO. The ITC combination with selected antibiotics had synergistic and additive effects.

In vitro antibacterial effect of Pimpinella anisum essential oil on Enterococcus faecalis, Lactobacillus casei, Actinomyces naeslundii, and Aggregatibacter actinomycetemcomitans.

Pimpinellaanisum is a medicinal plant with antimicrobial, antifungal, and anti-oxidative properties. Limited studies have assessed the antibacterial properties of Pimpinellaanisum on oral and dental pathogens.

Comparative antimicrobial activity of human and monkey origin lactic acid bacteria on simian enteric bacteria

Lactic acid bacteria as probiotics are intensively used in human and animal species. These probiotic properties of LABs were variable according to bacterial strain and species. However, there was limited information on probiotic properties of monkey origin LABs. In this study, we investigated the antibacterial activity of monkey and human origin LABs against monkey origin enteric bacteria by the agar disc diffusion test and broth culture inhibition assay. All LABs represented enough tolerance to pepsin (0.3%) and bile acid (pH = 2). To 50% of Clostridium perfringens and 20% of Escherichia coli, monkey origin LABs showed statistically higher antibacterial activity compared to human origin LABs (p &lt; 0.05). Also, distinct antibacterial activity was verified among some bacteria species and strains. Higher antibacterial activity against enteric bacteria except for C. perfringens was verified in Lactobacillus johnsonii strains compared to Lactobacillus reuteri and Lactobacillus salivarius. Statistically different antibacterial activity against C. perfringens was verified among strains within L. reuteri and L. johnsonii. In conclusion, we prove the higher probiotic properties of monkey origin LABs against homogenous enteric bacteria although humans and monkeys were phylogenetically similar species. For non-human primates, homogenous LABs should be used as probiotics, not human origin LABs. Furthermore, it was confirmed among monkey origin LABs, L. johnsonii showed a high antibacterial activity on various enteric pathogenic bacteria and was an appropriate lactic acid strain for inhibiting C. perfringens.

Bioreduction and Stabilization of Nanosilver using Chrysanthemum Phytochemicals for Antibacterial and Wastewater Treatment

AbstractAn easy, sustainable, and one‐step method has been explored to synthesize colloidal silver nanoparticles (AgNPs) using Chrysanthemum (CT) flower extract and applied for antibacterial treatment and azo dye catalysis. The synthesis parameters (effect of CT extract concentration, reaction temperature, time, and pH) were thoroughly examined via a one‐variable‐at‐a‐time (OVAT) method to identify an optimization condition. The characterization of AgNPs produced at as‐obtained optimum condition found that the nanoparticles are primarily spherical/oval shape, nanometer size (1.98±0.57 nm), very crystalline (d‐spacing=0.236 nm), significantly stabilized (zeta potential=−22.1 mV). The characterizations also indicated that the AgNPs were produced by the redox reaction between plant phytochemicals and metal cations and stabilized via encapsulation of plant phytochemicals. The bacterial resistivity AgNPs was monitored by the agar disk diffusion test and found to be highly effective towards both Staphylococcus aureus (+ev) and Escherichia coli (−ev) bacteria. Moreover, the synthesized AgNPs displayed an innate catalytic reduction of azo dyes such as acid red 1 (AR1) and acid blue 29 (AB29). The degradation reactions were followed pseudo‐first‐order kinetics model and the rate constants k were calculated to be 0.45528 min−1 (r2=0.94465) for AR1 and 0.28214 min−1 (r2=0.88764) for AB29, respectively. This study reveals the prospect of CT flower extract as a botanical source for the biosynthesis of AgNPs and its potential application in bacterial reduction and azo‐contaminated wastewater treatment.

Broad lytic spectrum of novel Salmonella phages on ciprofloxacin-resistant Salmonella contaminated in the broiler production chain.

Background and Aim:Ciprofloxacin (CIP) is recommended for salmonellosis treatment as the drug of choice; however, overuse of this drug can cause drug resistance issues and failure to treat diseases. Phage therapy is an alternative approach for combatting CIP-resistant infection. This study aimed to estimate the prevalence of CIP-resistant Salmonella isolated from the broiler production chain and evaluated the lytic ability of novel Salmonella phages isolated from water samples.Materials and Methods:Samples were obtained from the broiler production chain and used for Salmonella isolation. serovar and CIP resistance of each isolate were characterized through latex agglutination and agar disk diffusion test, respectively. Water samples from different sources were acquired for phage isolation. The lytic activity of novel-isolated phages was also examined.Results:In this study, 51 Salmonella isolates were recovered from the broiler production chain (two commercial farms, one free-range farm, two slaughterhouses, and three stalls from the wet market). Kentucky was the major serovar characterized (16), followed by Typhimurium (9), Agona (5), Corvalis (5), Schwarzengrund (5), Singapore (3), Weltevreden (3), Mbandaka (2), Give (2), and Albany (1). The serovars that exhibited CIP resistance were 14/16 isolates of serovar Kentucky (87.5%) and one isolate of serovar Give (50%), whereas eight other serovars were susceptible to this drug. Overall, the prevalence of CIP-resistant Salmonella recovered from the sources included in this study was 29.4%. This study identified 11 Salmonella phages isolated from wastewater samples derived from broiler farms, wastewater treatment stations, and natural reservoirs. Our phages showed the total percentage of lysis ability ranging from 33.3% to 93.3% against CIP-resistant isolates. However, only one bacterial isolate, namely 210SL, recovered from the food contact surface of a wet market stall and was resistant to all phages.Conclusion:Diverse serovars of Salmonella were recovered in the broiler production chain in this study, while the isolates presenting CIP-resistant Salmonella were as high as 29.4%. Overall, Salmonella phages showed high lysis ability against these CIP-resistant Salmonella isolates, suggesting the potential application of phage-based treatments or biocontrol in the broiler production chain.

Evaluation of the synergistic effect of cinnamon and probiotic filtrate against UTI

This study was designed to evaluate the effects of cinnamon and probiotics both alone and in combination against pathogenic bacteria isolated from UTI patients. One hundred and ten male and female patients with a urinary tract infection (UTI) who visited private health care facilities were asked to provide urine samples. The urine samples were inoculated on Blood and MacConkey agars and incubated for 24 hrs. at 37 degrees Celsius. After 24 hours of incubation, no development was seen in the cultures, thus they were kept in the incubator for a further 48 hours. Gram staining was used to classify bacteria, and then conventional microbiological culture and biochemical properties were used to identify the isolates. Cinnamomum bark oil was extracted manually. Mueller Hinton (MH) agar plates were infected with 108 CFU/ml suspensions of microorganisms; this method was used to determine the agar disc diffusion test. Discs of sterile Whatman paper No. 3 impregnated with 10 g of the compounds were placed on top of MH agar that had been infected with bacteria. For 18 hours, the plates were kept at 37°C. Inhibition zones against the various bacterial strains were used to evaluate the antibacterial impact.

Antimicrobial Activity of Silver Nanoparticles: An In-Vitro Study

To evaluate the antimicrobial activity of the silver nanoparticles suspended in Chitosan against Streptococcus mutans, the important causative pathogen for dental caries. Methodology: Antimicrobial activity was tested by performing the Agar Disc Diffusion test and the diameter of zone of inhibition (ZOI) was taken as the measure of antibacterial activity for the test sample (sample T), positive control, and negative control. The lack of formation of zone inhibition was construed as the absence of antibacterial activity. The antibacterial activity is articulated to be resistant, when a zone of inhibition of less than 7mm was observed, 8-10mm was construed as intermediate (8-10 mm), and ZOI more than 11 mm is construed as sensitive. The positive control Streptomycin was used as the standard. Results: The results showed potential antibacterial potency of silver nanoparticle against bacterial strains tested, Streptococcus mutans, compared to standard control used for the study.

An imperical analysis of various extracts of Bacopa Monnieri towards antibacterial and antifungal activities

Bacopa monnieri was also known as “Brahmi.” Theses plant has been considered as medicinal plants in Ayurvedic systems for centuries. This present study was carried out to evaluate the antibacterial and antifungal properties of ethanolic, diethyl ether, ethyl acetate, and aqueous extracts of B. monnieri. Agar disc diffusion tests were carried out to determine the antimicrobial effects of ethanolic, diethyl ether, ethyl acetate and aqueous extracts of B. monnieri against Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli) bacterial strains and antifungal strains (Aspergillus flavus, and Candida albicans). Among the various extracts, diethyl ether extracts of B. monnieri has an antibacterial potency against Staphylococcus aureus (gram positive), and ethyl acetate extract showed effects on E. coli (gram negative) at higher concentrations of 300 μg mL-1. The ethanolic extract has potent antifungal activity against the fungus (Aspergillus flavus, and Candida albicans) compared to diethyl ether and ethyl acetate-ether. Both extracts (diethyl ether and ethyl acetate) has a minimum antifungal effect while these extracts showed more inhibitory effects on tested bacteria.

Clavulanic Acid - Susceptible Peptide Spectra Tested with Agar Disk Diffusion and Epsilometer test of Urinary Tract Infected Escherichia coli Isolated from the Community-Acquired Infection

Abstract The present study aimed to investigate clavulanic acid susceptible peptide spectra in 174 community-acquired urinary tract infected Escherichia coli isolates using VITEK® MS. They were collected from bacteriuria samples at Diagnostic Laboratory Unit between January and May 2016. One hundred and fourteen multidrug resistant isolates were detected. Among these isolates, 13, 53, and 48 isolates were classified as the non, high, and low ESBL-producers, respectively by using Epsilometer strip test. Spectrum analysis was calculated for investigating the enzyme spectrum. The mass analysis and spectrum identification of ESBL-producing isolates were elucidated using the VITEK® MS apparatus. Among 58 peptide spectra, seven E. coli-specific spectra located at 3126, 3433, 6317, 6411, 7159, 9537, and 10301 Dalton (Da) were commonly detected in ≥ 85% of the total samples. Among the high ESBL-producing isolates, the spectrum intensity of four ceftazidime-resistant spectra which were located at 4613, 5613, 6508, 9713 Da was significantly increased after being exposed to ceftazidime as the ceftazidime-resistant spectra. Using agar disk diffusion, four clavulanic acid-susceptible spectra, 3433, 4613, 4768, and 9713 Da, were significantly detected after being co-exposed to ceftazidime and amoxicillin/clavulanic acid. Interestingly, the spectrum intensity of the significant spectrum, 9713 Da, was decreased after being co-exposed to ceftazidime plus clavulanic acid using an Epsilometer strip test. The interesting peptide spectra at 9713 Da significantly exhibited the clavulanic acid-susceptibility after being co-exposed to ceftazidime and clavulanic acid in both assays and could be suspected to be the ESBL indicative peptide spectra in the high ESBL-producing isolates. Keywords: VITEK® MS, Escherichia coli, ESBL, Clavulanic acid-susceptible peptide spectra, Community-acquired urinary tract infection

English

Asplenium serratum L. (Aspleniaceae) is a terrestrial, epiphytic or humicole fern used as traditional medicine in different countries to treat infection. As such, this study aimed to assess the antibacterial potential of a crude ethanol extract from A. serratum leaves against multidrug-resistant bacteria from a hospital setting. Fern leaves were dried and ground using 96&deg; Gay Lussac ethanol, with the extract concentrated in a rotary evaporator. Eleven bacterial strains were tested, including gram-positive (Enterococcus faecalis 1, Staphylococcus aureus, methicillin-sensitive S. aureus, S. aureus 8380, S. aureus ATCC 25923, Staphylococcus epidermidis) and gram-negative bacteria (Proteus mirabilis 464, Pseudomonas aeruginosa 36408, Enterobacter cloaceae 406, Klebsiella pneumoniae 6891, Escherichia coli 635). The disk agar diffusion test was used to assess the antimicrobial activity of the extracts. Disks of filter paper (5 mm wide) were prepared, each containing 5 &micro;l of different plant extract concentrations (5, 10, 15, 20, 30, 40 and 50 mg.ml-1, using dimethyl sulfoxide - DMSO -&nbsp; as solvent). The antibiotic oxacillin (1 mg) was used as a positive control and disks containing DMSO only as negative control. The Petri dishes and disks were incubated for 24 h (36.5-37&deg;C), after which the formation of zones of inhibition was measured. The tests were performed in duplicates. After incubation, all the positive control (oxacillin) disks contained zones of inhibition of bacterial growth, while none were observed for negative controls or the disks containing different concentrations of A. serratum extract. Ethanol extracts of A. serratum leaves showed no antibiotic activity against the microorganisms tested, precluding confirming the popular belief of anti-infective properties for this fern species for multidrug-resistant bacteria. Key words: Aspleniaceae, multidrug-resistant bacteria, ethnobotany, medicinal plants, ferns.

High faecal carriage of extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) among hospitalized patients at Sylvanus Olympio Teaching Hospital, Lomé, Togo in 2019

Background: Extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) are a global health concern, associated with increased morbidity and mortality. Even in the absence of infections, colonization by these pathogens is still a great threat because of the risk of cross transfer among hospitalized patients. Faecal carriage of ESBL-PE remained poorly documented in Africa. This study aimed to determine faecal carriage rate of ESBL-PE, factors associated with carriage, and antimicrobial susceptibility of the strains among hospitalized patients at Sylvanus Olympio Teaching Hospitals (CHU SO) in Lomé, Togo.&#x0D; Methodology: This was a cross-sectional study of 105 randomly selected hospitalized patients between September and November 2019. Socio-demographic and clinical data as well as rectal swabs were collected after obtaining the consent of the selected participants. Rectal swabs were cultured on selective bromocresol purple (BCP) lactose agar containing 6µg/l ceftazidime, for isolation of Enterobacteriaceae. Identification of each isolate was performed using Uriselect 4 medium and API 20E. Antibiotic susceptibility of the bacterial isolates was performed by the Bauer-Kirby agar disc diffusion test and interpreted according to CASFM-EUCAST recommendations.&#x0D; Results: The faecal carriage rate of ESBL-PE among selected hospitalized patients was 80.9% (85/105). Escherichia coli was the most frequent bacteria 69.5% (73/105), followed by Klebsiella pneumoniae 22.8% (24/105). The antibiotic profile of ESBL producing Escherichia coli showed resistance to amoxycillin+clavulanic acid (72.6%), ticarcillin+clavulanic acid (82.2%), piperacillin+tazobactam (30.1%), cefoxitin (30.1%) ciprofloxacin (84.9%), levofloxacin (76.7%), nalidixic acid (83.6%), chloramphenicol (26.0%), gentamicin (49.3%), sulfamethoxazole-trimethoprim (86.3%), imipenem (5.5%), and ertapenem (21.9%). All (100%) isolates were sensitive to amikacin and fosfomycin. None of the characteristics or risk factors assessed was significantly associated with faecal carriage of ESBL-PE.&#x0D; Conclusion: Faecal carriage rate of ESBL-PE in these hospitalized patients was very high, but no factor was associated with carriage of ESBL-PE among the study population. Implementation of infection control measures, and surveillance are needed to limit the spread of these resistant pathogens within CHU SO healthcare facilities.

Evaluation of antibacterial properties and shear bond strength of orthodontic composites containing silver nanoparticles, titanium dioxide nanoparticles and fluoride: An in vitro study.

The study aimed at determining the antibacterial properties of composites containing silver nanoparticles (Ag NPs) or titanium dioxide nanoparticles (TiO2 NPs), and a fluoride-releasing composite against Streptococcus mutans and Lactobacillus acidophilus, and to evaluate the effect on shear bond strength (SBS) of nanoparticles-modified composites. An orthodontic composite was modified by adding 1% w/w Ag NPs or 1% w/w TiO2 NPs. Composite discs were prepared to evaluate the antibacterial properties of these modified composites against Streptococcus mutans and Lactobacillus acidophilus, using three different antibacterial tests, namely: Disk agar diffusion test, Biofilm inhibition test and eluted component test. For evaluating the shear bond strength, 80 extracted premolars were collected and divided into four groups (n=20 each), which were bonded with stainless steel preadjusted Edgewise brackets, by using these modified composites. Their SBS was then compared with that of the control group, using a universal testing machine. Composite discs containing nanoparticles and fluoride were capable of producing growth inhibition zones for all bacterial types. Results of the biofilm inhibition test showed that all the study groups inhibited the bacterial count, in comparison to the control group. A significant difference of SBS was observed between all groups. The antibacterial activity of orthodontic composites modified with Ag and TiO2 nanoparticles was significant, compared with conventional and fluoride-containing composites. The control group showed the highest SBS, followed by fluoride, titanium, and silver groups, with statistically significant difference in mean SBS values among all groups.

High prevalence of blaVEB , blaGES and blaPER genes in beta-lactam resistant clinical isolates of Pseudomonas aeruginosa.

The increased prevalence of β-lactamase is one of the main factors in resistance to β-lactams in Pseudomonas aeruginosa. This study aimed to investigate the prevalence of blaVEB, blaPER, and blaGES genes in β-lactam-resistant P. aeruginosa. We collected 100 non-duplicated clinical isolates of P. aeruginosa and identified them by standard tests. Using disk agar diffusion test, we detected the β-lactam-resistant isolates and extracted the DNAs of the isolates by alkaline lysis method. Then, the prevalence of blaVEB, blaPER and blaGES genes were detected by PCR method. The results were assessed by SPSS 21 software and Chi-square test. Out of 100 isolates, 43% were detected as resistant against at least one of the beta-lactams tested. Piperacillin-tazobactam was the most effective antibiotic, while 39% and 37% of the isolates were resistant to aztreonam and meropenem, respectively. A significant relationship was observed between the resistance to tested antibiotics and the presence of blaVEB, blaGES, and blaPER genes. Among 43 isolates that were resistant to at least one of the tested β-lactams, 93.02%, 83.72%, and 81.39% of them carried blaVEB, blaGES, and blaPER genes, respectively. According to this study and due to high prevalence of β-lactam resistance genes, it is better to check the level of antibiotic resistance and resistance genes for better management of patients with infection caused by this bacterium. Also, high prevalence of class A β-lactamases indicates the significant role of these enzymes in emerging resistance to beta-lactams.

Characterisation of AmpC / ESBL genes in some pathogen gram-negatives isolated from clinical cases of livestock and companion animals

Abstract This study was aimed to search and characterize the AmpC and/or ESBL genes of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa isolated from clinical cases of local livestock and companion animals between 2017 and 2019. A total of eight ceftiofur-resistant E. coli (n= 7) and ceftiofur-resistant K. pneumoniae (n= 1) and seven P. aeruginosa were isolated from different cases in local animals. By combination disc method, six E. coli isolates and one K. pneumoniae isolate were found to be ESBL producers. By combination of the disc method and double disc synergy test, no P. aeruginosa isolates were found as ESBL producers. In the agar disc diffusion test (ADDT) performed with cefoxitin and cefoxitin-boronic, only one E. coli was determined as AmpC producer. In ESBL-producing isolates, only the CTX-M class gene was detected by polymerase chain reaction (PCR) and subsequent sequence analysis revealed CTX-M-3 and CTX-M-15 variants. An AmpC positive E. coli isolate was found to carry plasmidic ampC gene in cmy-2 variant from CIT family. It was observed that P. aeruginosa isolates did not carry the plasmidic ampC gene. After the chromosomal ampC gene of one P. aeruginosa was amplified by PCR and sequenced, R79Q and T105A mutations in the chromosomal ampC gene was revealed. This showed that overproduction of the ampC enzyme is involved in the resistance to β-lactams in P. aeruginosa isolates in the study.

Prevalence of ESBL and AmpC genes in E. coli isolates from urinary tract infections in the north of Iran

Beta-lactam resistance in Gram-negative bacteria, especially Escherichia coli, is a main clinical problem. It is often caused by the production of β-lactamases, particularly extended-spectrum β-lactamases (ESBLs) or AmpC enzymes. This study was undertaken to characterize ESBL and AmpC producers among Escherichia coli isolates from urine samples. During six months, 263 E. coli isolates were detected by standard biochemical tests. The isolates were screened for ESBL production by the double-disk synergy test using Ceftazidime (30 μg) and Cefotaxime (30 μg) disks and confirmed by combined disk diffusion test using Clavulanic acid. AmpC production was confirmed by an AmpC disk test based on filter paper disks impregnated with EDTA. The presence of genes encoding TEM, SHV, CTX-M, CIT, FOX, MOX, ACC, and EBC were detected by PCR. 263 E. coli isolates were selected for the combined disk (Ceftazidime, Cefotaxime, and Clavulanic acid) assay in the disk agar diffusion test. In the combined disk assay, among 263 isolates, 121 (46%) isolates were detected as ESBLs, and none of the isolates were AmpC producers. PCR performed on all ESBL producers and blaSHV, blaTEM, and blaCTX-M were detected in 42 (34.7%), 44 (36.4%), and 47 (38.8%) cases, respectively. Also, from 48 Isolates with zone diameters of less than or equal to 18 mm to Cefoxitin, 7 (14.6%), 4 (8.3%), and 9 (18.8%) cases contained MOX, EBC, and CIT genes, respectively. DHA, FOX, and ACC genes were not detected in any sample. Since pathogens evolve in the hospital setting, updating local data, such as this research, offers scientific evidence to improve the outcome of nosocomial infections.