Standard Agar Research Articles

The impact of agar depth on antimicrobial susceptibility testing by disc diffusion.

Introduction. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) specifies the agar depth (4±0.5 mm) when performing antimicrobial susceptibility testing (AST). Since the infrastructure to produce standardized agar may be lacking in settings with limited resources, we wanted to examine to what extent variation in agar depth affects the inhibition zone diameters of quality control (QC) strains and AST of clinical isolates.Methods. The inhibition zone diameters on Mueller-Hinton II agar with different depths (2-6 mm) were tested for various QC strain-antimicrobial agent combinations using Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213. The relationship between zone diameters at different agar depths and MICs was investigated for 35 clinical isolates (E. coli, Klebsiella pneumoniae, S. aureus and P. aeruginosa) from Sierra Leone using MICs as the reference.Results. The inhibition zone diameters were within the acceptance ranges as defined by the EUCAST for the majority of QC strains and antimicrobials, independent of the agar depth. At extreme agar depths, inhibition zones were more frequently out of range. The accuracy of AST varied for clinical isolates at different agar depths for categorical agreement (85.8-94.6%), major error rate (0.4-2.1%) and very major error rate (VME: 3.3-12.5%).Conclusions. Even if the QC strains were in the acceptance range at different agar depths, this does not rule out unacceptably high VME rates (>3%) in clinical isolates.

Fused Thiazolo[2,3‐b]Quinazolinone–Chromone Hybrids: Synthesis, Characterization, In Vitro Antibacterial Activity and In Silico Screening

ABSTRACTAntimicrobial resistance is one of the biggest threats to public health across the globe. Bacteria, fungi, viruses, and protozoans have been exhibiting resistance against antimicrobial drugs making them ineffective. Hence, the development of new antibiotics with a different mode of action is highly desirable. In this study, 10 new chromone‐incorporated fused thiazolo[2,3‐b]quinazolinone derivatives, 8a‐j, have been prepared via Biginelli reaction involving aromatic aldehydes, 1‐tetralone, and thiourea followed by a reaction with 2‐chloro‐N‐phenylacetamide, and Knoevenagel condensation with 3‐formylchromone. All the structures of the compounds were characterized by NMR, FTIR, and mass spectrometry. The in vitro antibacterial activities of all the synthesized compounds against the four different microbial strains were evaluated. Among them, few compounds demonstrated prominent activity against Staphylococcus aureus, Streptococcus pyogenes, and Pseudomonas aeruginosa. No appreciable activity of any compound against Klebsiella pneumoniae was observed. Molecular docking studies were employed to reveal the interactions responsible for the potent compounds' activities against S. aureus, S. pyogenes, and P. aeruginosa. Both in vitro and in silico studies have been carried out by using standard agar well diffusion protocol and Auto Dock Vina in PyRx. The results indicated that compound 8c was the potential compound as it showed good affinity toward the receptors of all three organisms. Molecular dynamics simulation of the 8c‐1JIJ complex for 100 ns further confirmed the potentiality of 8c. The pharmacokinetic properties of the compounds indicate that the studied molecules have exhibited a favorable profile.

Surveillance of In Vitro Activity of Cefiderocol Against Carbapenem-Resistant Gram-Negative Clinical Isolates in a Tertiary Care Hospital.

Antibiotic resistance among Gram-negative bacterial isolates is increasingly observed. With the emergence of carbapenem-resistant and pan-resistant pathogens, treating these resistant infections is becoming more challenging due to the limited number of effective drugs. There is a desperate need for the discovery of new antibiotics with novel mechanisms of action. Cefiderocol is one such novel antibiotic with a unique siderophore-based mechanism of action, which has been recently approved for clinical use against drug-resistant pathogens. The present study aims to identify the in vitro activity of cefiderocol against major carbapenem-resistant clinical isolates, including those resistant to colistin. One hundred and one carbapenem-resistant clinical isolates were included in the study. Identification and antibiotic susceptibility testing were performed using the automated VITEK® 2 Compact (bioMérieux SA, Marcy-l'Étoile, France) identification and susceptibility testing system, except for colistin and cefiderocol. Colistin resistance in Enterobacterales and Pseudomonas aeruginosa was assessed using the agar dilution minimum inhibitory concentration method, while for Acinetobacter baumannii, broth microdilution method was employed. Cefiderocol susceptibility testing was conducted using the Kirby-Bauer disc diffusion method with 30 µg discs on standard Mueller-Hinton agar plates. For selected isolates, cefiderocol minimum inhibitory concentration detection was performed using broth microdilution with iron-depleted cation-adjusted Mueller-Hinton broth. Of the total 101 isolates, the majority (75, 74.25%) were Enterobacterales which includedKlebsiella pneumonia (42, 41.58%) and Escherichia coli (33, 32.67%), followed by Pseudomonas aeruginosa (13, 12.87%) and Acinetobacter baumannii (10, 9.9%). Only three (2.97%)of the isolates were Stenotrophomonas maltophilia. Most of the isolates were susceptible to cefiderocol, with only four (3.96%) isolates showing resistance. Colistin resistance was observed in six (6.12%) of the isolates. There was a good correlation between disc diffusion testing and broth microdilution testing for the detection of cefiderocol-resistant isolates. No cross-resistance with colistin was observed, as all colistin-resistant isolates were uniformly susceptible to cefiderocol Conclusion: Cefiderocol is highly effective with good in vitro activity against the majority of carbapenem-resistant pathogens. While some isolates do show resistance, it is relatively uncommon. Given its safety profile compared to colistin, cefiderocol can serve as an alternative to colistin to treat carbapenem-resistant infections and it may be considered even for the management of colistin-resistant cases. Disc diffusion testing is a reliable method for identifying cefiderocol-resistant isolates in routine clinical and diagnostic laboratories, especially in resource-limited settings.

A single-layer spot assay for easy, fast, and high-throughput quantitation of phages against multidrug-resistant Gram-negative pathogens.

Double-layer agar (DLA) overlay plaque assay is the gold standard for phage enumeration. However, it is cumbersome and time-consuming. Given the great interest in phage therapy, we explored alternative assays for phage quantitation. A total of 16 different phages belonging to Myoviridae, Siphoviridae, and Podoviridae families were quantitated with five K. pneumoniae, eight P. aeruginosa, and three A. baumannii host isolates. Phages were quantitated with the standard DLA assay (10 mL of LB soft agar 0.7% on LB hard agar 1.5%) and the new single-layer agar (SLA) assay (10 mL of LB soft agar 0.7%) with phages spread (spread) into or spotted (spot) onto soft agar. Phage concentrations with each assay were correlated with the standard assay, and the relative and absolute differences between each assay and the standard double-layer agar spread were calculated. Phage concentrations 1 × 104-8.3 x1012 PFU/mL with the standard DLA assay were quantitated with SLA-spread, SLA-spot, and DLA-spot assays, and the median (range) relative and absolute differences were <10% and <0.98 log10PFU/mL, respectively, for all phage/bacterial species (ANOVA P = 0.1-0.43), and they were highly correlated (r > 0.77, P < 0.01). Moreover, plaques could be quantified at 37°C after 4-h incubation for K. pneumoniae phages and 6-h incubation for P. aeruginosa and A. baumannii phages, and estimated concentrations remained the same over 24 hours. Compared to DLA assay, the SLA-spot assay required less media, it was 10 times faster, and generated same-day results. The SLA-spot assay was cheaper, faster, easier to perform, and generated similar phage concentrations as the standard DLA-spread assay.

The therapeutic effects of Juglans regia Linn (Walnut) extracts on oral Candida infection

The difficulties associated with oral Candida infection management necessitate the development of novel antifungal medicines in order to widen the spectrum of activity against Candida albicans. The aim of this work is to study the oral anticandidal activity of Juglans regia L. cultivated in Algeria. This plant was chosen due to its traditional use for the treatment of oral infections. Methanolic, ethanolic, butanolic, ethylic acetate and acetonic extracts of the bark of J. regia L. were extracted in a Soxhlet device and screened for in vitro activity against C. albicans. Plant preparations were screened for antifungal activity using a standard agar well diffusion assay. Following a study of the antimicrobial activity of plant extracts, their minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values were determined using a broth microdilution assay. Among J. regia L. extracts, ethylic acetate extract had potent antifungal activity against Candida strain with diameters of inhibition ranging from 15.16±0.76 to 20.83±0.76 mm, followed by acetonic extract with diameters of inhibition ranging from 14.83±0.76 to 19.33±0.28 mm. The J. regia L. demonstrated MIC values ranging from 0.46875 to 3.75 mg mL-1 and the lowest MIC was recorded for ethylic acetate, acetonic extracts and AMB at 0.46875 mg mL-1. The ethylic acetate extract showed the lowest MFC value (0.9375 mg mL-1), followed by butanolic extract (3.125 mg mL-1). These results indicate that J. regia L. bark extracts can contain compounds with therapeutic potential against oral C. albicans and, hence, their possible use as therapeutic agents for oral candidiasis.

Inopinatus corneliae sp. nov. gen. nov. isolated from human skin: A newly discovered keratinophilic hyphomycete, order Onygenales.

Fungi clinically relevant to human skin comprise prevalent commensals and well-known pathogens. Only rarely human skin harbours fungi that evade identification. To characterise an enigmatic specimen isolated from a skin lesion. A comprehensive clinical and mycological workup including conventional methods for phenotypic characterisation and sequencing based on internal transcribed spacer (ITS) and large subunit (LSU) regions to infer a phylogenetic tree. Cultures on common solid media were macroscopically inconspicuous initially until mycelial tufts developed on the surface, notably on potato dextrose agar. Polymorphous chlamydospores were detected but no aleurospores and ascomata. At 26°C, the isolate grew on standard agars, plant materials and garden soil and utilised peptone, keratins, lipids, inulin, erythrocytes and cellulose. It also grew at 5°C and at 37°C. Nucleotide sequences of its ITS region showed 93% similarity to sequences of different Malbranchea species. The closest matches among LSU rRNA sequences were obtained with the genera Amauroascus, Arthroderma, Auxarthronopsis and Malbranchea (93%-95%). A combined phylogenetic analysis placed the fungus in a sister clade to Neogymnomycetaceae, classified as incertae sedis in Onygenales, on a large distance to either Diploospora rosea or 'Amauroascus' aureus. The genus Inopinatus gen. nov. (MB854685) with the species Inopinatus corneliae sp. nov. (MB854687) is introduced to accommodate our isolate (holotype: DSM 116806; isotypes: CBS 151104, IHEM 29063). Probably Inopinatus corneliae is a geophilic species that, although potentially harmful, was no relevant pathogen in our case. Its ecology, epidemiology and pathogenicity need to be further clarified.

Antisera against flagellin A or B inhibits Pseudomonas aeruginosa motility as measured by novel video microscopy assay

Flagellum-mediated motility is essential to Pseudomonas aeruginosa (P. aeruginosa) virulence. Antibody against flagellin reduces motility and inhibits the spread of the bacteria from the infection site. The standard soft-agar assay to demonstrate anti-flagella motility inhibition requires long incubation times, is difficult to interpret, and requires large amounts of antibody. We have developed a time-lapse video microscopy method to analyze anti-flagellin P. aeruginosa motility inhibition that has several advantages over the soft agar assay. Antisera from mice immunized with flagellin type A or B were incubated with Green Fluorescent Protein (GFP)-expressing P. aeruginosa strain PAO1 (FlaB+) and GFP-expressing P. aeruginosa strain PAK (FlaA+). We analyzed the motion of the bacteria in video taken in ten second time intervals. An easily measurable decrease in bacterial locomotion was observed microscopically within minutes after the addition of small volumes of flagellin antiserum. From data analysis, we were able to quantify the efficacy of anti-flagellin antibodies in the test serum that decreased P. aeruginosa motility. This new video microscopy method to assess functional activity of anti-flagellin antibodies required less serum, less time, and had more robust and reproducible endpoints than the standard soft agar motility inhibition assay.

Use of Viscous medium to study anthelmintic drug action in Caenorhabditis elegans

Caenorhabditis elegans is an appealing tool for experimental evolution and for working with antiparasitic drugs, from understanding the molecular mechanisms of drug action and resistance to uncover new drug targets. We present a new methodology for studying the impact of antiparasitic drugs in C. elegans. Viscous medium was initially designed for C. elegans maintenance during long-term evolution experiments. Viscous medium provides a less structured environment than the standard nematode growth media agar, yet the bacteria food source remains suspended. Further, the Viscous medium offers the worm population enough support to move freely, mate, and reproduce at a rate comparable to standard agar cultures. Here, the Viscous medium was adapted for use in antiparasitic research. We observed a similar sensitivity of C. elegans to anthelmintic drugs as in standard liquid media and statistical difference to the standard agar media through a larval development assay. Using Viscous medium in C. elegans studies will considerably improve antiparasitic resistance research, and this medium could be used in studies aimed at understanding long-term multigenerational drug activity.

Inhibition of Ralstonia solanacearum by Warburgia ugandensis stem bark and leaf crude extracts obtained using organic solvents

Ralstonia solanacearum is a soil-borne bacterial pathogen that poses significant threat to the Solanaceae family and other crops. It causes widespread bacterial wilt, a devastating disease that affects the plant's water transport system, leading to wilting and death. Numerous chemical agents and treatment methods have been employed in attempts to control R. solanacearum, but are ineffective. The study aimed to determine the in vitro efficacy of W. ugandensis stem bark and leaf crude extracts against R. solanacearum. W. ugandensis stem bark and leaf crude extracts were obtained using organic solvents viz. methanol, ethanol, dichloromethane and hexane. In vitro, antagonistic activities against R. solanacearum of all organic crude extracts of W. ugandensis were determined by standard agar well diffusion assay on Kelman’s 2, 3, 5- triphenyl tetrazolium chloride medium in triplicates. Two-way analysis of variance (ANOVA) was used in the statistical analysis of the mean diameter inhibition zones. All the organic solvents crude extracts of W. ugandensis were inhibitive against R. solanacearum. However, the stem bark crude extracts exhibited significantly higher efficacy against R. solanacearum compared to the leaf crude extracts. The crude extracts were subjected to a serial dilution to determine the minimum inhibitory concentration (MIC). W. ugandensis stem bark dichloromethane crude extracts had the lowest MIC of 1 mg/ml. W. ugandensis stem bark dichloromethane crude extracts were most effective against R. solanacearum. Further research is important to determine the bioactive compounds against R. solanacearum in W. ugandensis stem bark dichloromethane crude extracts.

Antimicrobial Susceptibility Pattern of Bacterial Pathogens in Our Setup: Ear, Nose and Throat Perspective

With a high prevalence of infections involving the ear, nose, and throat, and the occurrence of drug resistance the antimicrobial susceptibility pattern of bacterial pathogens is of immense importance. Objective: To determine the antimicrobial sensitivity profile of pathogenic bacteria isolated from representative infected areas of patients with ear, nose, and throat infections. Methods: This cross-sectional observational study was conducted at Ear, Nose and Throat (ENT) Outpatient Department (OPD), Capital Hospital Islamabad, over two years. The sample included 639 pathogenic bacterial culture specimens, grown from the representative infected ear, nose, or throat of patients who attended ENT outpatients of the hospital. The bacterial cultures were subjected to the standard disc agar diffusion method to know the antimicrobial susceptibility profile. Data collected included the patient’s age, gender, area/ site of infection, bacterial pathogen isolated, and sensitivity to antibiotics. Results: The sample included 49.30% males and 50.70% females and mean age of 30.13±19.24 years. Gram-positive organisms were predominant [n=441, (69.01%)] with Staphylococcus aureus being the commonest isolate (67.92%) followed by Pseudomonas spp. (26.13%). Gram-positive isolates were sensitive to Cefoperazone+Sulbactam, Ceftazidime, Cefoperazone, Amikacin, Pipercillin+Tazobactam, Vancomycin, Gentamycin, Linezolid, Amoxicillin + Clavulanate, and Ceftriaxone with resistance to Cefixime, while the Gram-negative isolates were sensitive to Vancomycin and Meropenum, Ciprofloxacin, Levofloxacin, Ceftriaxone and Ceftazidime and highly resistant to Cefixime, Cefuroxime, Amoxicillin+Clavulanate and Co-trimoxazole. Conclusions: Since ENT infections are predominated by Staphylococcus aureus and Pseudomonas spp. When unavoidable the empirical therapy should cover these pathogens, however culture and sensitivity studies are justified keeping in view the growing resistance to antimicrobials.

Unveiling colistin resistance in extensively drug-resistant microorganisms among ICU patients of tertiary care hospital Karachi, Pakistan

Objective: To determine the prevalence of extensively drug-resistant (XDR) microorganisms in the intensive care unit (ICU) of a tertiary care hospital in Karachi and to identify the presence of colistin resistance (CLR) among these XDR isolates. Material and Methods: A cross sectional study was carried out in the ICU of a tertiary care hospital from August 2022 to February 2023 and various clinical samples of XDR Gram negative bacilli (GNB) were collected from ICU. These specimens were processed by following the guidelines established by the Clinical and Laboratory Standards Institute (CLSI), Agar and broth microdilution methods were used to assess the colistin susceptibility of XDR isolates. Results: The study focused on 100 extensively drug-resistant (XDR) specimens. K. Pneumoniae dominated (32%), followed by E. coli (23). Among the 100 XDR, 89% were colistin susceptible, and 11% were resistant, tested by agar and broth microdilution. Of the 11% CLR, P. aeruginosa was most common, with the highest resistance in urine specimens. Colistin resistance was highest for P. aeruginosa (45%), followed by A. baumannii (18%), E. coli (18%), K. Pneumoniae (9%), and K. oxytoca (9%). CLR isolates were mainly (27%) from urine. Conclusion: Prolonged hospital stays and antibiotic pressure can lead to CLR development. Labs should monitor XDR closely, implementing measures to minimize antibiotic resistance. Controlling colistin resistance through stewardship is crucial. Keywords: Extensively drug resistant, Colistin resistant, Minimum inhibitory concentration, Nasobronchial lavage

Phytochemical Properties and In vitro Antimicrobial Activity of Methanolic Leaf Extract of Durio zibethinus Murr. on Selected Clinical Isolates

Bacterial and viral infections represent the most challenging diseases to treat in humans due to resistance to most of the therapeutic agents. The advent of drug resistance factors that have challenged the effectiveness of all antimicrobial agents prompted the investigation of antimicrobial activity studies of the methanolic leaf extract of Durio zibethinus Murr. This study is focused on evaluating the phytochemical and antimicrobial activity of the leaf extract of D. zibethinus Murr. on selected clinical isolates: Staphylococcus aureus and Staphylococcus epidermidis (gram-positive bacterial strains), Klebsiella pneumonia, Escherichia coli, Salmonella typhi (gram-negative bacterial strains) while Candida albicans and Microsporum audouinii (fungi strains) using the standard agar disc diffusion technique. Alkaloids, saponins, flavonoids, terpenoids, steroids, glycosides, and phenolic chemicals have all been identified via phytochemical investigation. The result indicated that the leaf extract exhibited antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Candida albicans and Microsporum audouinii at a range of 10.34–16.02 mm at a concentration of 150 mg/mL relative to standard gentamicin and fluconazole antibiotics. The minimum inhibitory concentration (MIC) for S. aureus was 0.250 mg/mL; for E. coli, it was 0.125 mg/mL; whereas it was 0.250 mg/mL for the two fungal strains, C. albicans and M. audouinii. Our investigation revealed that the D. zibethinus Murr. leaf extract exhibited the highest antibacterial activity against S. aureus and E. coli whereas the extract exhibited the highest antifungal activity against M. audouinii. Our research concluded that the Durio zibethinus Murr. leaf extract had potent antibacterial and antifungal properties, suggesting that it could be utilized to treat various pathogenic diseases.

Antimicrobial resistance patterns, virulence genes, and biofilm formation in enterococci strains collected from different sources

BackgroundCurrently, antibiotic-resistant strains of Enterococcus are considered to be one of the critical health challenges globally. This study aimed to investigate the antibiotic susceptibility pattern, biofilm formation capacity, and virulence genes of enterococci isolated from different sources.MethodsIn this cross-sectional study, environmental and fecal samples were collected from the hospital environment, volunteers, and hospital staff from October 2018 to August 2019. The isolates were identified by morphological and biochemical tests (gram staining, catalase, bile resistance, esculin hydrolysis, carbohydrate fermentation, growth in 6.5% NaCl, Pyrrolidonyl arylamidase, arginine dehydrolase), and PCR for ddl gene. An antimicrobial susceptibility test was performed by the standard disk agar diffusion method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Quantitative microplate assays were used to assess biofilm production. The bacterial DNAs were extracted by alkaline lysis method and polymerase chain reaction technique was used detect the esp, ace, and efaA virulence genes.ResultsOut of 145 isolates, 84 (57.9%) were identified as E. faecalis and 61 (42.1%) as E. faecium. Resistance to kanamycin and quinupristin-dalfopristin was 82.1% (69/84) and 85.7% (72/84), respectively, in E. faecalis isolates. Out of 61 E. faecalis isolates, 38 (62.4%) were resistant to kanamycin. Among the E. faecalis isolates, esp was the most dominant virulence gene (73.80%), followed by efaA, and ace, which were detected in 60.71%, and 30.95% isolates, respectively. In total, 68.27% of the strains were biofilm producers. Further, esp and efaA genes were more frequently found among E. faecalis strains with moderate and strong biofilm biomass.ConclusionsAccording to the findings of our study, enterococci strains isolated from different samples possess distinctive patterns of virulence genes. The esp, ace, and efaA genes were more prevalent among E. faecalis than E. faecium. Besides, the high level antibiotic resistance of normal flora and environmental enterococci strains is alarming the researchers.

Performance evaluation of a Test&Treat rapid detection kit for the diagnosis of septic effusions in dogs and cats.

To evaluate the sensitivity and specificity of a veterinary point-of-care (POC) luminometer-based kit for the diagnosis of septic peritoneal or pleural effusion in dogs and cats. Prospective study performed between January 2020 and July 2021. University teaching hospital. Forty-eight animals with naturally occurring peritoneal or pleural effusion collected by aseptic abdominocentesis or thoracocentesis. Effusion samples were split into filtered (using a 10-micron filter) and unfiltered aliquots and analyzed by the POC instrument according to the manufacturer's instructions and following variable incubation periods. Samples were also plated aerobically on standard and blood agar plates. Proprietary reagents were added to samples, causing bacterial ATP to generate bioluminescence that is detected by the luminometer. Bioluminescence values (relative light units [RLUs]) were recorded and compared with the presence of bacterial growth on the culture plates. Nucleated cell counts in native and filtered effusion samples were recorded. Twenty-one samples were septic based on positive culture. RLUs were higher in septic effusions for filtered and native effusions compared with sterile effusions. The use of a filter reduced cell counts. In filtered samples incubated for 30minutes before testing, the sensitivity and specificity of the luminometer for diagnosis of infection in cavitary effusions were 81% and 82%, respectively, using a cutoff of 12,202 RLUs. The luminometer kit evaluated in this study represents a viable screening tool for diagnosis of septic cavitary effusions and could be used in conjunction with other POC diagnostics to support the rapid diagnosis of infection.

In vitro susceptibility of Neisseria gonorrhoeae to netilmicin and etimicin in comparison to gentamicin and other aminoglycosides

PurposeSingle doses of gentamicin have demonstrated clinical efficacy in the treatment of urogenital gonorrhea, but lower cure rates for oropharyngeal and anorectal gonorrhea. Formulations selectively enriched in specific gentamicin C congeners have been proposed as a less toxic alternative to gentamicin, potentially permitting higher dosing to result in increased plasma exposures at the extragenital sites of infection. The purpose of the present study was to compare the antibacterial activity of individual gentamicin C congeners against Neisseria gonorrhoeae to that of other aminoglycoside antibiotics.MethodsAntimicrobial susceptibility of three N. gonorrhoeae reference strains and 152 clinical isolates was assessed using standard disk diffusion, agar dilution, and epsilometer tests.ResultsGentamicin C1, C2, C1a, and C2a demonstrated similar activity against N. gonorrhoeae. Interestingly, susceptibility to the 1-N-ethylated aminoglycosides etimicin and netilmicin was significantly higher than the susceptibility to their parent compounds gentamicin C1a and sisomicin, and to any other of the 25 aminoglycosides assessed in this study. Propylamycin, a 4’-propylated paromomycin analogue, was significantly more active against N. gonorrhoeae than its parent compound, too.ConclusionSelectively enriched gentamicin formulations hold promise for a less toxic but equally efficacious alternative to gentamicin. Our study warrants additional consideration of the clinically established netilmicin and etimicin for treatment of genital and perhaps extragenital gonorrhea. Additional studies are required to elucidate the mechanism behind the advantage of alkylated aminoglycosides.

Biofabrication of silver nanoparticles with Feijoa sellowiana tailored by box-behnken design: An eco-friendly approach to enhance antifungal properties in Children's toothpaste

Oral candidiasis and its association with dental caries necessitate the development of toothpaste with enhanced antifungal properties, particularly for children at high risk of infection. This study aims to investigate the antifungal efficacy of children's toothpaste incorporating biosynthesized silver nanoparticles (AgNPs) using Feijoa sellowiana. Silver fluoride and Feijoa leaf extract were used for the synthesis of AgNPs. The independent variables were the concentration of AgF, pH of the extract, and temperature. The optimized formula was obtained using Design Expert software and Box-Benken design. The physicochemical properties of AgNPs were evaluated by UV-absorption wavelength measurements, SEM, and TEM analyses. Finally, the powder of optimized AgNPs was added to Colgate Kids Toothpaste® and its antifungal effect was evaluated using the standard agar well diffusion method. The optimization process identified an AgF concentration of 8 mM, a pH value of 9.56, and a temperature of 58 °C as influential factors for the formulation. The optimized AgNPs exhibited a size of 42.75 nm, and SEM and TEM analyses confirmed their spherical shape. Both toothpaste formulations, with and without AgNPs, demonstrated antifungal activity. Although the antifungal effect of both toothpaste types against Candida glabrata did not show a significant difference (p > 0.088), the toothpaste containing AgNPs exhibited significantly higher antifungal efficacy against Candida albicans (p < 0.014). In conclusion, the biosynthesis of silver nanoparticles using silver fluoride and Feijoa leaf extract as an eco-friendly approach can effectively enhance the antifungal potency of toothpaste against C. albicans.

Prevalence and molecular characteristics of heterogeneous vancomycin intermediate Staphylococcus aureus in a tertiary care center of northern China

The use of glycopeptide medications may decline in line with the annual decline in methicillin-resistant Staphylococcus aureus (MRSA) detection rates in China. The rate of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA)detection may be impacted by this. However, there is currently a dearth of information on the incidence of hVISA in China. This study aims to analyze the recent epidemiology and molecular characteristics of hVISA strains in Beijing, China. A total of 175 non-duplicate MRSA strains from various infection sites were collected from a medical center between January 2018 and May 2023 and underwent molecular typing and susceptibility testing (Vitek2). Vancomycin and teicoplanin MICs were also evaluated by standard broth microdilution method and agar dilution method, respectively. Isolates growing on screening agar (BHIV4 and BHIT5, brain heart infusion agar containing 4 μg/ml vancomycin and 5 μg/ml teicoplanin, respectively) were characterized further by analysis of macro-Etest (MET) and population analysis profiling with area under the curve (PAP-AUC). The proportion of hVISA among MRSA isolates was 8.6 %. BHIT5 could select all hVISA strains while BHIV4 and MET only selected two hVISA strains. Compared with vancomycin- susceptible Staphylococcus aureus (VSSA), hVISA isolates were less susceptible to erythromycin and clindamycin. In addition, hVISA frequency was MIC-independent despite using different detection methods. In total, 11 types of STs, 28 types of spa typing, four types of SCCmec typing, and two types of agr typing were identified and the predominant type in both MRSA and hVISA isolates was ST239-t030-SCCmecIII-agr I. The analysis of biofilm formation, growth, and virulence genes in hVISA strains revealed sparse information. The dataset presented in this study provided the prevalence and molecular characteristics of hVISA in hospital settings and the combination of BHIT5 and PAP-AUC may identify hVISA efficiently. The result of genotyping suggested the genotype of hVISA was mainly consistent with that of local MRSA. Additional studies on the characteristics of hVISA strains were necessary.

Identification on seed associated mycoflora of sesame genotypes

Seed mycoflora of 165 genotypes of sesame in (AVTs &amp; IVTs) were detected using seed health testing methods viz., paper towel method, standard blotter method, and standard agar plate method and six distinct fungi viz.,Alternaria, Macrophomina, Fusarium, Aspergillus, Penicillium, and Rhizopus spp. were detected. In the three methods employed to identify seed mycoflora the standard blotter method has identified the maximum number of seeds infected by fungi compared to paper towel method and standard agar plate method. After a few days of germination, it was observed that the majority of the seeds were infected with disease, which hampered normal seedling growth and resulted in abnormal and rotted seedlings.

Investigation of antimicrobial and physical properties of polyester/cotton blended knitted fabric treated with AgNO3 and aloe vera

The application of antimicrobial textiles is rising rapidly because of their healthcare, comfort, and hygienic attributes. This work aimed to develop an antibacterial polyester/cotton (50/50) blended knitted fabric coated with silver nitrate (AgNO3) and a natural aloe vera gel. In the present investigation, Polyester/Cotton (50/50) blended knitted fabrics have been treated by exhaust method using various concentrations of AgNO3 such as 0.5%, 0.75%, 1.0%, and aloe vera gel 25%, 40%, and 50%, respectively. The antibacterial performance of the coated textiles has been assessed qualitatively against Staphylococcus aureus and Salmonella bacteria by the standard agar diffusion technique (AATCC-147 test method). Furthermore, the effects of AgNO3 and aloe vera have been investigated in terms of tensile strength, elongation at break, and tear strength of the coated textiles. The experimental results showed that both the Aloe vera gel and AgNO3 have significant antibacterial action against Staphylococcus aureus and Salmonella bacteria. However, the blended knitted fabric treated with aloe vera gel showed a superior antibacterial activity against both bacteria than fabric finished with AgNO3. The functional elements of aloe vera and AgNO3 in treated materials were investigated using Fourier transform infrared spectroscopy and the surface morphology is revealed using FESEM. Finally, cost analysis shows that antimicrobial polyester/cotton blended fabrics can be developed with eco-friendly aloe vera at the cheapest cost compared to expensive AgNO3

Spectrophotometrically, Spectroscopically, Microscopically and Thermogravimetrically Optimized TiO2 and ZnO Nanoparticles and their Bactericidal, Antioxidant and Cytotoxic Potential: A Novel Comparative Approach.

Current study was aimed to determine the antibacterial, antioxidant and cytotoxic potential of Titanium dioxide nanoparticles (TiO2NPs) and Zinc oxide nanoparticles (ZnONPs). Nanoparticles were characterized by UV-Vis spectrophotometry, particle size analyzer (PSA), fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy(SEM), and thermogravimetric analysis (TGA). The Minimum inhibitory concentration (MIC) was determined by standard agar dilution method. Antibacterial potential of nanoparticles was analyzed by standard disc diffusion method against bacterial strains including Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia. Different concentrations of NPs (0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4mg/mL) were incorporated to evaluate the antimicrobial activity. Antioxidant activity and cytotoxicity of these NPs was analyzed by DPPH method and brine shrimp cytotoxicity assay, respectively. The MIC of TiO2NPs against E. coli, P. aeruginosa and K. pneumoniae was 0.04, 0.08 and 0.07mg/mL respectively while the MIC of ZnONPs against the above strains was 0.01, 0.015 and 0.01mg/mL. The maximum zone of inhibition was observed for K. pneumoniae i.e., 20mm and 25mm against TiO2 and ZnO NPs respectively, at 1.4mg/mL concentration of NPs. The susceptibility of NPs against bacterial strains was evaluated in the following order: K. pneumoniae > P. aeruginosa > E. coli. The antioxidant activity of nanoparticles increased by increasing the concentration of NPs while cytotoxic analysis exhibited non-toxic effect of ZnO NPs while TiO2 had toxic effects on 1.2 and 1.4mg/mL concentrations. Results revealed that ZnO NPs have moreantibacterialand negligiblecytotoxic potential in contrast to TiO2 NPs.