Lowest Minimum Inhibitory Concentration Value Research Articles

SARS-CoV-2 Post-Infection and Sepsis by Saccharomyces cerevisiae: A Fatal Case Report—Focus on Fungal Susceptibility and Potential Virulence Attributes

The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for approximately 6.8 million deaths worldwide, threatening more than 753 million individuals. People with severe coronavirus disease-2019 (COVID-19) infection often exhibit an immunosuppression condition, resulting in greater chances of developing co-infections with bacteria and fungi, including opportunistic yeasts belonging to the Saccharomyces and Candida genera. In the present work, we have reported the case of a 75-year-old woman admitted at a Brazilian university hospital with an arterial ulcer in the left foot, which was being prepared for surgical amputation. The patient presented other underlying diseases and presented positive tests for COVID-19 prior to hospitalization. She received antimicrobial treatment, but her general condition worsened quickly, leading to death by septic shock after 4 days of hospitalization. Blood samples collected on the day she died were positive for yeast-like organisms, which were later identified as Saccharomyces cerevisiae by both biochemical and molecular methods. The fungal strain exhibited low minimal inhibitory concentration values for the antifungal agents tested (amphotericin B, 5-flucytosine, caspofungin, fluconazole and voriconazole), and it was able to produce important virulence factors, such as extracellular bioactive molecules (e.g., aspartic peptidase, phospholipase, esterase, phytase, catalase, hemolysin and siderophore) and biofilm. Despite the activity against planktonic cells, the antifungals were not able to impact the mature biofilm parameters (biomass and viability). Additionally, the S. cerevisiae strain caused the death of Tenebrio molitor larvae, depending on the fungal inoculum, and larvae immunosuppression with corticosteroids increased the larvae mortality rate. In conclusion, the present study highlighted the emergence of S. cerevisiae as an opportunistic fungal pathogen in immunosuppressed patients presenting several severe comorbidities, including COVID-19 infection.

In-vitro Cytotoxicity, Anti-bacterial and Anti-inflammatory Activities of Ecklonia radiata and Jania verrucosa from Eastern Cape, South Africa

Seaweeds are marine floras constituting in part to over 90% of the oceanic biomass. Despite the enrichments of seaweeds, their potentials are largely unexplored. Hence, this study evaluated the phytochemical screening, antimicrobial, anti-inflammatory and cytotoxicity activities of methanolic extracts of Ecklonia radiata and Jania verrucosa. E. radiata and J. verrucosa were collected from sites on the rocky shores of the Mbashe and Port St. John rivers on the Eastern Cape coast of South Africa during spring low tides. Qualitative phytochemical screening was carried out using standard protocol. The assessment of anti-inflammatory activity was done by inhibition of albumin denaturation assay and antimicrobial analysis was performed against six different pathogenic clinical isolates. The cytotoxicity effect of the methanolic extracts were further investigated on MDA-MB-231, HepG2, CaCo-2 and KMST-6 by (3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay (MTT assay). Phytochemical analysis revealed the presence of tannins, phenols, glycosides, and alkaloid for both extracts. The methanolic extracts of both seed weeds also possess anti-inflammatory activity by inhibiting albumin denaturation. The average minimum inhibitory concentration (MIC) values of the plantextracts ranged from 160-10000 µg/mL. J. verrucosa methanolic extract had the most significant biological activity with the lowest MIC value (160 µg/ml). The cytotoxicity result showed that cells treated with the methanolic extracts of E. radiata and J. verrucosa have more cytotoxicity effect on MDA-MB-231 treated cells followed by HepG2 and CaCo-2. Non-cancerous cell line (KMST-6) however showed some selectivity in their activities. Among the cancer cell lines, HepG2 treated cells were significantly suppressed (p < 0.05) with both extracts compared to 5µM camptothecin (standard drug). In conclusion, E. radiata and J. verrucosa have potential for chemoprevention of human breast, good anti-inflammatory and antibacterial activities.

The Antibacterial Effect of Boron Compounds and Evaluation of the Effects on Biofilm Formation in the Infection Model of Klebsiella pneumoniae on the HepG2 Cell Line

Aim: Klebsiella pneumoniae causes hospital-acquired pneumonia, urinary tract infection and bacteremia in immunocompromised patients. Klebsiella pneumoniae, which has become more common recently, causes antibiotic resistance as well as pyogenic liver abscesses and hematogenous metastatic spread in humans. Developing antibiotic resistance complicates the treatment of liver infections. In our study, we aimed to evaluate the effect of boron compounds in an infection model created by Klebsiella pneumoniae 700603. Materials and Methods: Minimum inhibitory concentration and fractional inhibitory concentration studies, resistance gene levels, and HepG2 cell analyses were performed and evaluated. Results: We determined the low and high minimum inhibitory concentration values of boron components, sodium perborate monohydrate and etidote, respectively. In addition, sodium perborate monohydrate is also effective on biofilm formation. Our findings have shown that boron compounds are more effective when used in a combination. In the toxicity model created in the cellular study, the boron compounds cytotoxic effect decreased due to their antibacterial effects. Conclusion: İt seems that boron compounds are effective, and the positive effect increases when used together.

Luliconazole: A Novel Potent Imidazole Activity against Aspergillus niger and Aspergillus flavus Causing Otomycosis

Background: Aspergillus niger and Aspergillus flavus are the most common causative agents of otomycosis with worldwide distribution. Extensive surgical debridement and systemic antifungal therapy are needed in cases of refractory otomycosis. Luliconazole is currently confirmed for the topical therapy of dermatophytosis. Moreover, it is found that luliconazole has in vitro activity against some molds and yeast species. Objectives: The aim of the present study was to evaluate the efficacy of luliconazole in comparison to routinely used triazole antifungals on Aspergillus isolates, obtained from otomycosis cases using microbroth dilution method. Materials and Methods: This study was carried out in the department of microbiology, from March 2020 to February 2022. A total of 55 strains of Aspergillus isolates obtained from otomycosis cases were confirmed based on macroscopic and microscopic identification. Antifungal susceptibility patterns of itraconazole, voriconazole, posaconazole and luliconazole were determined by broth microdilution method as per the Clinical Laboratory Standards Institute M38-A2 guidelines. Results: Among the azoles tested, the lowest minimum inhibitory concentration (MIC) geometric mean (0.00309 μg/ml), MIC50 (0.00098 μg/ml), and MIC90 (0.00781 μg/ml) values were attributed to luliconazole. Being the drug of choice for aspergillosis, voriconazole had a slightly higher MIC50 and MIC90 value of 1 μg/ml and 2 μg/ml, respectively. Even for the pan azole resistant isolates (n = 3), luliconazole was found to be more effective with lower MIC values. Conclusion: The results of this study showed that luliconazole had an excellent in vitro activity with a lower MIC values than the triazoles tested. Hence, this novel imidazole antifungal agent can be considered an appropriate candidate for the treatment of otomycosis caused by A. niger and A. flavus strains. Furthermore, luliconazole showed better efficacy with lower MIC values for pan azole resistant isolates, suggesting that it could be a potential antifungal for treating aspergillosis caused by pan azole resistant isolates.

Clinico-Mycological Profile of Recurrent Dermatophytosis with Drug Sensitivity in a Tertiary Care Center in Southern Odisha

Background: Recurrent dermatophytosis is a pressing problem worldwide due to inadequate treatment, drug resistance, and indiscriminate use of topical steroids. This scenario increases the need for the study of risk factors and antifungal susceptibility testing. There is a paucity of information on this subject. Objective: We aimed to find the clinico-mycological pattern of recurrent dermatophytic infections, the factors responsible for recurrence and determine the sensitivity pattern of isolates against four antifungals (fluconazole, itraconazole, terbinafine, and amphotericin B). Materials and Methods: Patients with recurrent dermatophytosis attending the outpatient Department of Our Tertiary Care Institute were enrolled in this study. A detailed history was taken; clinical examination was done; samples were collected for mycological examinations, and in-vitro antifungal sensitivity testing was done by broth microdilution method as per Clinical and Laboratory Standard Institute M38-A guidelines. Results: One hundred and twenty-eight patients were included in the study with a male:female ratio of 1.38:1. The most commonly affected age group was 31–40 years. Tinea corporis with tinea cruris was the most common type of clinical presentation. Potassium hydroxide mount was positive in 53 samples and culture was positive in 59 samples. Trichophyton rubrum was the predominant species isolated, followed by Trichophyton mentagrophytes. On in-vitro antifungal susceptibility testing, itraconazole and amphotericin B had the lowest minimum inhibitory concentrations (MIC), followed by terbinafine. Fluconazole had the highest MIC among the drugs tested. Conclusion: Topical corticosteroid abuse, lack of personal hygiene, and habit of sharing clothes were seen in many patients with recalcitrant dermatophytosis. T. rubrum was the most common isolated species. Antifungal susceptibility testing revealed itraconazole and amphotericin B to have the lowest MIC value and fluconazole to have the highest MIC value.

Synthesis of biologically important tetrahydroisoquinoline (THIQ) motifs using quantum dot photocatalyst and evaluation of their anti-bacterial activity.

Our study introduces an efficient photocatalytic approach for synthesizing biologically significant C1-substituted tetrahydroisoquinoline (THIQ) motifs, employing WS2 quantum dots (QDs) as catalysts. This method enables the formation of C-C and C-P bonds at the C1 position of the THIQ motif. The resulting compounds exhibit substantial antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) bacteria, with low minimum inhibitory concentration (MIC) values. Notably, the WS2 QD catalyst demonstrates recyclability and suitability for gram-scale reactions, underscoring the sustainability and scalability of our approach. Overall, our research presents a versatile and cost-effective strategy for synthesizing C1-substituted THIQ derivatives, highlighting their potential as novel therapeutic agents in biology and medicinal chemistry.

Potential application of menadione for antimicrobial coating of surgical sutures

Staphylococcal-associated surgical site infections (SSI) are common nosocomial infections in healthcare facilities worldwide. The use of antiseptic-coated sutures has been recommended to minimise the risk of SSI in clinical settings. However, as there has been a growing concern over antibiotic resistance resulting from antiseptic usage, development of antimicrobial sutures using alternative compounds is necessary. In this study, menadione (2-methyl-1,4-napthoquinone), also known as Vitamin K3, was evaluated as a potential antimicrobial compound for suture coating. The anti-staphylococcal activity of menadione was assessed using microbroth dilution method and biofilm inhibition assays. The low menadione minimum biofilm inhibitory concentration values against both methicillin-susceptible and -resistant S. aureus strains indicate its inhibitory activity against staphylococcal biofilm. Menadione-coated sutures were prepared by dip-coating surgical sutures in slurries containing poly(D,L-lactide-co-glycolide) polymers (either 65:35 or 75:25) and calcium stearate. Zone of inhibition assays showed dose-dependent antimicrobial effects of the sutures up to four days. A ∼3 log10 colony forming unit/ml reduction of adherent bacteria (p < 0.05) on the sutures was demonstrated via bacterial adherence assays. The integrity and tensile strength of the sutures were unaffected by the coating procedure. In view of the increased antibiotic resistance and limited antimicrobials, menadione may be potentially useful for antimicrobial coating of surgical sutures.

A Study on Subsite-specific Prevalence of Candidiasis in Head and Neck Cancer Patients and its Antifungal Susceptibility Pattern: A Cross-sectional Study

Introduction: The incidence of candidiasis can vary across various subsites within the head and neck region and is associated with various co-morbidities and risk factors. The increase in the incidence of resistant Non-albicans Candida (NAC) species among these patients and the limited number of available antifungal agents make treatment difficult. A better understanding of the subsite-specific prevalence of candidiasis and its antifungal susceptibility is crucial in enhancing effective control and treatment. Aim: To determine the subsite-specific prevalence of candidiasis among Head and Neck Cancer (HNC) patients undergoing radiotherapy. Materials and Methods: A cross-sectional study was conducted on patients undergoing therapy for head and neck malignancies at the Department of Radiation Oncology, Amala Institute of Medical Sciences, Thrissur, Kerala, India over a four-year period (January 2019 to December 2022). A total of 276 patients aged 18 to 85 years with squamous cell carcinoma were included. Oral samples were collected from patients who developed candidiasis, and co-morbidities and risk factors were documented. Candida species were isolated and identified. Antifungal susceptibility was determined using the VITEK system, and fluconazole susceptibility was compared with the standard disc diffusion method. Data were entered into an Excel sheet and analysed using Statistical Package for the Social Sciences (SPSS) software. Results: Pharynx was the most frequent site of head and neck malignancy, accounting for 104 cases (37.7%), followed by the oral cavity with 83 cases (30.1%). Among patients with malignancies in the pharyngeal region, a high rate of Candida infection was observed in 42 (43.3%) out of 97 cases. Candida species isolated included C. albicans (56, 57.7%), C. tropicalis (26, 26.8%), C. krusei (8, 8.3%), C. glabrata (3, 3.1%), and C. parapsilosis (4, 4.1%). Sixty-five patients (23.5%) had diabetes, which was statistically significant (p-value &lt;0.05). All C. albicans strains were sensitive to fluconazole. The Minimum Inhibitory Concentration (MIC) of voriconazole was very low for all tested Candida species. Conclusion: Patients with pharyngeal and oral cavity carcinomas are at an increased risk of developing candidiasis during radiotherapy. Diabetes is significantly associated with candidiasis. While C. albicans was the most common species isolated, a significant number of NAC species were also identified. Voriconazole exhibited low MIC values for C. krusei and C. glabrata, suggesting its potential as an alternative treatment option. Obtaining VITEK system identification and susceptibility reports is advisable for borderline values that may not be evident using conventional disc diffusion methods.

Distribution of MIC values of antibacterial drugs for Flavobacteriales isolated from respiratory samples in Russian patients with cystic fibrosis

Objective. Analysis of the distribution of the values of the minimum inhibitory concentrations (MIC) of a number of antibacterial drugs in relation to representatives of the order Flavobacteriales isolated from respiratory samples from patients with cystic fibrosis of the Russian Federation by the method of double serial dilutions. Materials and Methods. The distribution of the values of MIC of a number of antibacterial drugs was evaluated in relation to 100 strains of bacteria, representatives of the order Flavobacteriales, isolated from respiratory samples from patients with cystic fibrosis from 60 regions of the Russian Federation as part of a routine microbiological examination. Of these, 75 representatives of Chryseobacterium spp., among which C. arthrospherae – 28, C. formosense – 1, C. gambrini – 3, C. gleum – 10, C. indologenes – 20, C. joostei – 1, C. oraniemense – 10, C. shandongense – 2 strains, 4 strains of Elizabethkingia spp., among which 2 – E. miricola, and one strain of E. meningoseptica and E. anopheles, respectively, as well as 21 strains of E. falsenii. Identification of all isolated cultures was carried out using MALDI-ToF mass spectrometry (Bruker, Germany). The MIC values were determined for 17 antimicrobial drugs: amikacin, amoxicillin/clavulanate, aztreonam, cefotaxime, ceftazidime, ceftazidime/avibactam, ceftolozane/ tazobactam, ciprofloxacin, colistin, ertapenem, gentamicin, imipenem, meropenem, piperacillin/ tazobactam, tigecycline, tobramycin and trimethoprim/sulfamethoxazole using Sensititre kits DKMGN. Results. The MIC values of colistin, cefotaxime and tobramycin more than 8 µg/ml, as well as more than 2 µg/ml with respect to ertapenem was demonstrated for 100% of isolates. For most strains, the MIC values of imipenem and meropenem were more than 4 µg/ml. MIC of ceftazidime against 20% of Chryseobacterium spp. strains was up to 2 µg/ml. Indicators of MIC of amikacin in relation to Elizabethkingia spp. strains were 32 µg/ml or more. For 38% of the strains of Chryseobacterium spp. and E.falsenii, this value did not exceed 8 µg/ml. As in the case of amikacin, all Elizabethkingia spp. strains demonstrated high levels of gentamicin MIC – 8 µg/ml (25% of strains) and more (75% of strains). For 20% of all tested strains, the MIC value was in the range of ≤ 2 µg/ml. In relation to half of the tested isolates, the MIC values for ceftazidime/avibactam, as well as ceftolozane/tazobactam were at the level of up to 2⁄4 µg/ml inclusive. More than a third of the strains had a level of MIC ciprofloxacin up to 0.25 µg/ml inclusive. For 25% of strains, the level of MIC of tigecycline was up to 0.5 µg/ml, inclusive, the lowest MIC indicators for the tested group of strains were demonstrated for trimethoprim/sulfamethoxazole: for 88% of strains, the MIC value was ≤ 1⁄19 µg/ml, for another 9% of strains, this indicator was 2⁄38 µg/ml. Conclusions. Representatives of the order Flavobacteriales are a group of microorganisms characterized by multiple antibiotic resistance. Most strains isolated from patients with cystic fibrosis in the Russian Federation retain low MIC values for trimethoprim/sulfamethoxazole.

A Study on Subsite-specific Prevalence of Candidiasis in Head and Neck Cancer Patients and its Antifungal Susceptibility Pattern: A Cross-sectional Study

Introduction: The incidence of candidiasis can vary across various subsites within the head and neck region and is associated with various co-morbidities and risk factors. The increase in the incidence of resistant Non-albicans Candida (NAC) species among these patients and the limited number of available antifungal agents make treatment difficult. A better understanding of the subsite-specific prevalence of candidiasis and its antifungal susceptibility is crucial in enhancing effective control and treatment. Aim: To determine the subsite-specific prevalence of candidiasis among Head and Neck Cancer (HNC) patients undergoing radiotherapy. Materials and Methods: A cross-sectional study was conducted on patients undergoing therapy for head and neck malignancies at the Department of Radiation Oncology, Amala Institute of Medical Sciences, Thrissur, Kerala, India over a four-year period (January 2019 to December 2022). A total of 276 patients aged 18 to 85 years with squamous cell carcinoma were included. Oral samples were collected from patients who developed candidiasis, and co-morbidities and risk factors were documented. Candida species were isolated and identified. Antifungal susceptibility was determined using the VITEK system, and fluconazole susceptibility was compared with the standard disc diffusion method. Data were entered into an Excel sheet and analysed using Statistical Package for the Social Sciences (SPSS) software. Results: Pharynx was the most frequent site of head and neck malignancy, accounting for 104 cases (37.7%), followed by the oral cavity with 83 cases (30.1%). Among patients with malignancies in the pharyngeal region, a high rate of Candida infection was observed in 42 (43.3%) out of 97 cases. Candida species isolated included C. albicans (56, 57.7%), C. tropicalis (26, 26.8%), C. krusei (8, 8.3%), C. glabrata (3, 3.1%), and C. parapsilosis (4, 4.1%). Sixty-five patients (23.5%) had diabetes, which was statistically significant (p-value &lt;0.05). All C. albicans strains were sensitive to fluconazole. The Minimum Inhibitory Concentration (MIC) of voriconazole was very low for all tested Candida species. Conclusion: Patients with pharyngeal and oral cavity carcinomas are at an increased risk of developing candidiasis during radiotherapy. Diabetes is significantly associated with candidiasis. While C. albicans was the most common species isolated, a significant number of NAC species were also identified. Voriconazole exhibited low MIC values for C. krusei and C. glabrata, suggesting its potential as an alternative treatment option. Obtaining VITEK system identification and susceptibility reports is advisable for borderline values that may not be evident using conventional disc diffusion methods.

In vitro antimicrobial activity of Bixa orellana L . Leaves extract against anaerobic bacteria associated to bacterial vaginosis and Lactobacillus spp.

Motivation for the study: bacterial vaginosis is a bacterial infection that frequently affects women of reproductive age. The treatment is based on synthetic antimicrobials. Bixa orellana L. possesses antimicrobial properties and could represent a potential non-synthetic therapeutic alternative. Main findings: in vitro results suggest that, methanolic extract of Bixa orellana L. leaves possesses potential antimicrobial properties against bacteria associated to bacterial vaginosis. Implications: to identify new sources with therapeutic potential, and to promote research, discovery, and characterization of non-synthetic antimicrobials. To describe the in vitro antimicrobial activity of the methanolic extract of Bixa orellana L. leaves against anaerobic bacteria associated to bacterial vaginosis and Lactobacillus spp. Eight ATCC reference strains; Gardnerella vaginalis, Prevotella bivia, Peptococcus niger, Peptostreptococcus anaerobius, Mobiluncus curtisii, Atopobium vaginae, Veillonella parvula, and Lactobacillus crispatus, and twenty-two clinical isolates; eleven Gardnerella vaginalis and eleven Lactobacillus strains, were included in the study. The antimicrobial susceptibility was determined by the agar diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by using agar dilution and a modified dilution plating method, respectively. All ATCC reference strains showed high levels of susceptibility to the extract, except P. vibia, V. parvula and L. crispatus. Interestingly, all G. vaginalis clinical isolates and the G. vaginalis ATTC strain were the most susceptible to the extract, given their low MIC (1.0 - 2.0 mg/mL) and MBC (1.0 - 4.0 mg/mL) values, whereas, the Lactobacillus spp. clinical isolates and the L. crispatus ATCC strain were the least susceptible bacteria given their high MIC (32.0 mg/mL) and MBC (≥ 32.0 mg/mL) values. In vitro experiments suggest that the extract possesses selective antimicrobial properties given its high activity against bacterial vaginosis-associated anaerobic bacteria and low activity against Lactobacillus species.

Correlation between the microbiome and pack burst spoilage of Allium sativum supplemented fermented hot pepper paste

Gochujang (fermented hot pepper paste) products are well known for their distinct, spicy flavor. However, frequent pack burst spoilage of gochujang products occurs during transportation and storage because of microbial aerogenesis, resulting in considerable economic losses. The present study aimed to prevent pack burst spoilage of gochujang products by supplementing them with garlic ethanol extract. A simulated pack burst experiment revealed that 42.86 % of normal gochujang products were spoiled. Garlic ethanol extract significantly inhibited the growth of Zygosaccharomyces rouxii in gochujang products, with low minimum inhibitory concentration values (12.5–25 mg/mL). Gochujang products supplemented with various concentrations (1 % and 2.5 %) of garlic ethanol extract exhibited marked inhibition of microbial growth, particularly Z. rouxii, and pack burst spoilage. Microbiome analysis revealed that the pack burst samples harbored a high abundance of Z. rouxii. Supplementation of gochujang with 1 % garlic ethanol extract drastically reduced Z. rouxii abundance and prevented pack burst. Moreover, gochujang products supplemented with 1 % garlic ethanol extract exhibited a high hedonic score in the sensory analysis. Based on the results of this study, we concluded that supplementation of gochujang products with 1 % garlic ethanol extract before packaging could be effective in preventing pack burst spoilage of gochujang.

In vitro evaluation of gentamicin activity against Spanish field isolates of Brachyspira hyodysenteriae

BackgroundThe treatment of swine dysentery (SD) has become constrained in recent years due to the limited availability of effective drugs combined with a rise in antimicrobial resistance. Gentamicin, an aminoglycoside antibiotic, is authorised for the control of this disease in several European countries but has not been extensively used so far. In this study, the in vitro susceptibility of 56 Brachyspira hyodysenteriae field isolates was evaluated against gentamicin using a broth microdilution test. The molecular basis of decreased susceptibility to gentamicin was also investigated by sequencing the 16S rRNA gene and phylogenetic relatedness by multiple-locus variable number tandem-repeat analysis (MLVA).ResultsMost B. hyodysenteriae isolates presented low minimum inhibitory concentration (MIC) values to gentamicin, with a mode of 2 µg/mL, a median or MIC50 of 4 µg/mL and percentile 90 or MIC90 of 16 µg/mL. The distribution of these values over the period studied (2011–2019) did not show a tendency towards the development of resistance to gentamicin. Differences in susceptibility among isolates could be explained by two point-mutations in the 16S rRNA gene, C990T and A1185G, which were only present in isolates with high MICs. These isolates were typed in three different MLVA clusters. Analyses of co-resistance between gentamicin and antimicrobials commonly used for the treatment of SD revealed that resistance to tiamulin and valnemulin was associated with low MICs for gentamicin.ConclusionsThe results provide an accurate characterisation of antimicrobial sensitivity to gentamicin and possible mechanisms of resistance in Spanish B. hyodysenteriae isolates. These findings allow us to propose gentamicin as an alternative in the antibiotic management of SD, particularly in outbreaks caused by pleuromutilin resistant isolates.

Screening for broad-spectrum antimicrobial endophytes from Rosa roxburghii and multi-omic analyses of biosynthetic capacity.

Plants with certain medicinal values are a good source for isolating function-specific endophytes. Rosa roxburghii Tratt. has been reported to be a botanical source of antimicrobial compounds, which may represent a promising candidate for screening endophytic fungi with antimicrobial potential. In this study, 54 endophytes were isolated and molecularly identified from R. roxburghii. The preliminary screening using the plate confrontation method resulted in 15 different endophytic strains showing at least one strong inhibition or three or more moderate inhibition against the 12 tested strains. Further re-screening experiments based on the disc diffusion method demonstrated that Epicoccum latusicollum HGUP191049 and Setophoma terrestris HGUP190028 had excellent antagonistic activity. The minimum inhibitory concentration (MIC) test for extracellular metabolites finally indicated that HGUP191049 had lower MIC values and a broader antimicrobial spectrum, compared to HGUP190028. Genomic, non-target metabolomic, and comparative genomic studies were performed to understand the biosynthetic capacity of the screened-out endophytic fungus. Genome sequencing and annotation of HGUP191049 revealed a size of 33.24 megabase pairs (Mbp), with 24 biosynthetic gene clusters (BGCs), where the putative antimicrobial compounds, oxyjavanicin, patulin and squalestatin S1 were encoded by three different BGCs, respectively. In addition, the non-targeted metabolic results demonstrated that the strain contained approximately 120 antimicrobial secondary metabolites and was structurally diverse. Finally, comparative genomics revealed differences in pathogenicity, virulence, and carbohydrate-active enzymes in the genome of Epicoccum spp. Moreover, the results of the comparative analyses presumed that Epicoccum is a promising source of antimicrobial terpenes, while oxyjavanicin and squalestatin S1 are antimicrobial compounds shared by the genus. In conclusion, R. roxburghii and the endophytic HGUP191049 isolated from it are promising sources of broad-spectrum antimicrobial agents.

A Bioluminescence-Based Drug Screen Identifies Activities of Fexinidazole and Its Metabolites against Helicobacter pylori.

Helicobacter pylori is responsible for a wide range of gastric diseases, including gastric cancer and gastritis. With half of the world's population infected by H. pylori and the current standard of care associated with suboptimal outcomes, a search for more effective drugs is critical. To facilitate drug screening for H. pylori, we developed a microtiter plate-based compound screening method that is faster and can screen multiple compounds. We identified activities of fexinidazole and its sulfoxide and sulfone metabolites against H. pylori. Both fexinidazole and its metabolites exhibited equipotency against SS1, 60190, and G27 strains, which were about 3-6-fold more potent than the currently used metronidazole. We also determined the minimal inhibitory concentration (MIC) of metronidazole, fexinidazole, and its metabolites against these strains by a traditional agar plate-based method. While MIC values of fexinidazole and metronidazole were similar against all the strains, both sulfoxide and sulfone showed lower MIC values than metronidazole against SS1 and 60190. Given the recent FDA approval of fexinidazole, our data on the in vitro antibacterial activities of fexinidazole and its metabolites support further evaluation of this drug with the goal of producing an alternative nitro-based antimicrobial with good safety profiles for the treatment of H. pylori infection.

Assessment of in vitro antibacterial activity and MIC of cinnamon bark powder ethanolic and aqueous extracts against bacteria

The study was planned to evaluate the in vitro antibacterial activity and minimum inhibitory concentration (MIC) of cinnamon (Cinnamomum zeylanicum) bark powder ethanolic and aqueous extracts. Screening of cinnamon powder ethanolic and aqueous extracts for antibacterial sensitivity and MIC against Staphylococcus aureus, Streptococcus agalactiae, Bacillus cereus, Listeria monocytogenes, Escherichia coli and Pseudomonas aeruginosa was carried out. ABST was performed by the disc diffusion method. The cinnamon powder ethanolic and aqueous extracts were suspended in a solution containing 10% dimethyl sulfoxide and 0.5% tween 80. Under aseptic condition, empty sterilized discs were impregnated with 50 μl of different concentrations (50%, 25%, 12.5%, 6.25% and 3.12%) of the cinnamon powder ethanolic and aqueous extracts and placed on the agar plate surface. Paper disc moistened with vehicle (DMSO plus tween 80) was placed on the seeded petri plate as a vehicle control. Standard disc containing antibacterial drugs (gentamicin, tetracycline, cefpirome and ampicillin) were used as reference control. The petri plates were incubated at 37°C for 18 h. After the incubation period, the zone of inhibition was measured. Among the tested bacteria, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Escherichia coli showed the sensitivity at different concentration of cinnamon powder ethanolic extract whereas Streptococcus agalactiae and Pseudomonas aeruginosa showed no zone of inhibition. Aqueous extract of cinnamon powder showed no antibacterial activities against all tested bacteria. The minimum inhibitory concentration of cinnamon powder ethanolic and aqueous extracts were determined by micro-broth dilution technique. The results of MIC revealed that both ethanolic and aqueous extracts showed various MIC against all tested bacteria. Ethanolic extract of cinnamon powder has lower MIC value against Staphylococcus aureus among tested bacteria.

Synthesis, Characterization, and Biological Evaluation of Tetrahydropyrimidines: Dual-Activity and Mechanism of Action.

In this paper, the synthesis, characterization, and biological evaluation of the novel tetrahydropyrimidines—THPMs are described. THPMs are well-known for wide pharmacological activities such as antimicrobial, anticancer, antiviral, etc. This research includes obtained results of in vitro antimicrobial, anticancer, and α-glucosidase inhibitory activities of the eleven novel THPMs. An antibiotic assessment was done against five bacteria (two Gram-positive and three Gram-negative) and five fungi by determining the minimal inhibitory concentration (MIC), using the broth tube dilution method. The most active antibacterial compounds were 4a, 4b, and 4d, while the best antifungal activity was shown by 4e, 4f, and 4k. The lowest MIC value (0.20 mg/mL) was measured for 4e, 4f, and 4k against the Trichophyton mentagrophytes. Moreover, examining the α-glucosidase inhibitory activity revealed the compound 4g as the one with the best activity. The cytotoxic activity was performed on the tumor cell lines (HeLa, K562, and MDA-MB-231) and normal cells (MRC-5). The best antitumor activity was shown by compounds 4b and 4k against HeLa cell lines. The influence on cell cycle and mechanism of action of the most active compounds were examined too. Compound 4b had good antibacterial and anticancer activities, while 4k showed promising antifungal and anticancer activities.

Eco-Friendly Solution Based on Rosmarinus officinalis Hydro-Alcoholic Extract to Prevent Biodeterioration of Cultural Heritage Objects and Buildings.

Biodeterioration of cultural heritage is caused by different organisms capable of inducing complex alteration processes. The present study aimed to evaluate the efficiency of Rosmarinus officinalis hydro-alcoholic extract to inhibit the growth of deteriogenic microbial strains. For this, the physico-chemical characterization of the vegetal extract by UHPLC–MS/MS, its antimicrobial and antibiofilm activity on a representative number of biodeteriogenic microbial strains, as well as the antioxidant activity determined by DPPH, CUPRAC, FRAP, TEAC methods, were performed. The extract had a total phenol content of 15.62 ± 0.97 mg GAE/mL of which approximately 8.53% were flavonoids. The polyphenolic profile included carnosic acid, carnosol, rosmarinic acid and hesperidin as major components. The extract exhibited good and wide spectrum antimicrobial activity, with low MIC (minimal inhibitory concentration) values against fungal strains such as Aspergillus clavatus (MIC = 1.2 mg/mL) and bacterial strains such as Arthrobacter globiformis (MIC = 0.78 mg/mL) or Bacillus cereus (MIC = 1.56 mg/mL). The rosemary extract inhibited the adherence capacity to the inert substrate of Penicillium chrysogenum strains isolated from wooden objects or textiles and B. thuringiensis strains. A potential mechanism of R. officinalis antimicrobial activity could be represented by the release of nitric oxide (NO), a universal signalling molecule for stress management. Moreover, the treatment of microbial cultures with subinhibitory concentrations has modulated the production of microbial enzymes and organic acids involved in biodeterioration, with the effect depending on the studied microbial strain, isolation source and the tested soluble factor. This paper reports for the first time the potential of R. officinalis hydro-alcoholic extract for the development of eco-friendly solutions dedicated to the conservation/safeguarding of tangible cultural heritage.

Chemical composition and antimicrobial properties of Moroccan Mentha pulegium L. essential oil

The aim of the study was the determination of the chemical composition of Moroccan Mentha pulegium L. essential oil (MpEO) and the evaluation in vitro of its antibacterial activity for using such as a natural antibiotic. MpEO was extracted by steam distillation method, and the chemical composition was determined using GC–MS analysis, in which pulegone (74.88 %), d-Limonene (8.69 %), 2-(2,2,4-Trimethyl-3-cyclopenten-1-yl) ethanol (5.43 %), and verbenone (3.21 %) represented the major compounds for MpEO. The antibacterial activity of the EO against seven bacteria strains: three strains of Escherichia coli serotypes, three strains of Salmonella (S. kentucky, S. newport, S. infantis) and Klebsiella strain was assessed by using the agar disc diffusion method, and by determining the minimum inhibitory concentration (MIC). The result shows that the lowest MIC value was obtained with MpEO against Escherichia coli andKlebsiella (MIC = 246.08 μL/mL).

P022 Luliconazole—a novel potent imidazole activity against Aspergillus niger and Aspergillus flavus causing otomycosis

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM Background and ObjectivesSuppurative otitis media (SOM) is characterized by the inflammation of the middle ear and mastoid, tympanic membrane perforation as well as discharge. The tympanic membrane perforation may result in increased exposure of the middle ear to pathogens. Aspergillus niger and Aspergillus flavus, are the most common causative agents of otomycosis with worldwide distribution, when it spreads from the external auditory canal to adjacent anatomical structures, it is classified as Aspergillus invasive otitis externa. Aspergillus otomycosis treatment is initiated by thorough cleaning of the ear canal, accomplished with suction, and drying with cotton swabs. In developing countries, SOM is a major cause of preventable hearing loss, its incidence ranges from 7% to 46% and is common amongst children of lower socioeconomic status. Treatment of SOM is directed at debridement and drying the ear with topical antifungal agents. Extensive surgical debridement and systemic antifungal therapy are needed in cases of refractory otomycosis or Aspergillus invasive otitis externa. Despite this management, treatment failure may result from suboptimal therapeutic management caused by antifungal agent toxicity. Luliconazole is currently confirmed for the topical therapy of dermatophytosis. Moreover, it is found that luliconazole has in vitro activity against some molds and yeast species. The aim of the present study was to evaluate the efficacy of luliconazole in comparison to routinely used antifungals on clinical isolates of A. niger and A. flavus.MethodsThe study was carried out in the Department of Microbiology, SRIHER, Chennai. A total of 55 (29 A. niger and 26 A. flavus) strains of Aspergillus isolates obtained from clinical otomycosis cases were confirmed based on macroscopic and microscopic identification by Lacto Phenol Cotton Blue mount and slide culture technique. Antifungal susceptibility patterns of all the Aspergillus isolates to itraconazole, voriconazole, posaconazole, and luliconazole were determined by broth microdilution method as per Clinical Laboratory Standards Institute (CLSI) M38-A2 guidelines.ResultsThe lowest minimum inhibitory concentration (MIC) geometric mean (GM) (0.00309 μg/ml) was attributed to luliconazole followed by posaconazole (0.18409 μg/ml), voriconazole (1.02727 μg/ml) and itraconazole (11.0091 μg/ml). Also, among the azoles tested, luliconazole had the lowest MIC50 and MIC90 values of 0.00098 μg/ml and 0.00781 μg/ml respectively. Among the triazoles tested posaconazole had a lower MIC50 and MIC90 values of 0.125 μg/ml and 0.25 μg/ml. Being the drug of choice for invasive aspergillosis voriconazole had a slightly higher MIC50 and MIC90 value of 1 μg/ml and 2 μg/ml. Luliconazole was found to be more effective even for pan azole-resistant isolates (n = 3) with lower MIC values.ConclusionThe results of this study showed that luliconazole had an excellent in vitro activity against all Aspergillus isolates with a lower MIC GM, MIC50, and MIC90 values than the triazoles tested. Hence, this novel imidazole antifungal agent can be regarded as appropriate Candidate for the treatment of otomycosis caused by A. niger and A. flavus strains. Also, luliconazole showed better efficacy with lower MIC values for pan azole resistant isolates, suggesting that it could be a potential antifungal for treating aspergillosis caused by pan azole-resistant isolates.