Minimum Inhibitory Concentration Range Research Articles

In-vitro antimicrobial activity of essential oils of Tasmania

ABSTRACT Thirteen commercial Tasmanian essential oils were evaluated for their antimicrobial activity against 14 human pathogens and cosmetic contaminants including Enterococcus hirae, Kocuria rhizophila, Staphylococcus epidermidis, Propionibacterium acnes, Staphylococcus aureus, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Pluralibacter gergoviae, Pseudomonas fluorescens, Burkholderia cepacia, Pseudomonas putida, Aspergillus brasiliensis, and Aspergillus fumigatus. The antimicrobial activities of various essential oils were evaluated using the AlamarBlue Cell Viability Assay, covering a testing concentration range from 3.125 to 800 µg/mL. Essential oils were deemed active if their minimum inhibitory concentration (MIC) value was less than or equal to 800 µg/mL. The essential oils of Rosemary (Rosmarinus officinalis ct. α-pinene), Parsley Herb (Petroselinum crispum), and Bitter Fennels (Foeniculum vulgare) demonstrated significant growth inhibitory effects on one microorganism (P. fluorescens) within an MIC value of ≤ 800 µg/mL. Big Badja Gum (Eucalyptus badjensis), Blue Gum (Eucalyptus globulus), Peppermint (Mentha piperita), and Lavender (Lavandula angustifolia) essential oils inhibited the growth of two different microorganisms. Southern Rosalina (Melaleuca ericifolia), Parsley Seed (Petroselinum crispum), Smoky Tea Tree (Leptospermum glaucescens), and Kunzea (Kunzea ambigua) essential oils exhibited an MIC value of less than or equal to 800 µg/mL against 4, 5, 6, and 8 microorganisms respectively. Notably, Coastal Tea Tree (Leptospermum laevigatum) essential oil displayed the most profound antimicrobial activity, inhibiting 11 out of 15 microbial strains within an MIC range of 50–800 µg/mL. The results of the gas chromatography analysis showed that the coastal tea tree essential oil was composed primarily of monoterpenes, with smaller amounts of sesquiterpenes and their oxygenated derivatives. 35 Compounds were identified, representing 95.50% of the compounds in the coastal tea tree essential oil. The main constituents of this essential oil were α-pinene (34.83%), followed by α- and β-eudesmols (10.21% total), and limonene (9.56%).

Elucidating the Role of Plant Extracts Mediated Gold Nanoparticles as Smart Antimicrobials: Two-Way Attack

Pathogenic bacteria remain the primary health concern even after developing a broad spectrum of antibiotics. The emergence of drug-resistant strains increased mortality, perhaps resulting in a never-ending future pandemic. The researchers are currently concentrating their efforts on nanotechnology-based therapies to counteract resistance. The present review focuses on the antimicrobial characteristics of plant-mediated gold nanoparticles (Au NPs). First, the methodology and importance of green synthesis are highlighted. Variability in NPs characterization methods was identified, with dynamic light scattering, zeta potential, and thermogravimetric analysis limited to a few investigations. Second, the Au NPs synthesized using different plant extracts were found to be broad-spectrum antimicrobial agents against Pseudomonas aeruginosa, Escherichia coli, Cryptococcus neoformans, Candida glabrata, Aspergillus niger, etc. The lowest minimum inhibitory concentrations range (1.95–15.62 µg/mL) was observed with Au NPs synthesized using Thymus vulgaris extract against Staphylococcus aureus, P. aeruginosa, Bacillus subtilis, and E. coli. The effect was more pronounced with smaller NPs (<10 nm). The activity of Au NPs might be mediated through a two-way attack which includes nanoparticles’ diverse mechanisms like reactive oxygen species generation, etc., and surface-attached phytocompounds such as flavonoids, alkaloids, phenolics, terpenoids, tannins, etc. The futuristic role of nanotechnology-based interventions in managing microbial infections is imperative. Synergistic interactions of Au NPs with antibiotics, toxicity profiling, stability, and bioavailability could be major areas of NPs research.

Antifungal activity of three different varieties of Capsicum annuum against clinical isolates of Candida species

ObjectiveAcquired resistance to antifungal agents is rising among Candida species. Herbal extracts including Capsicum annum extracts have biological profits, which can be employed to overcome drug resistance in fungal species. The present study investigated the efficacy of different varieties of C. annum extracts against Candida species.MethodsAqueous and alcoholic extracts of three different varieties of C. annum were prepared using the succulent method. Total values for compound extracts of C. annum var. cayenne, C. annum var. cayenne cultivar sabzevari, and C. annum var. cerasiforme were 43, 42, and 38 g, respectively. The clinical Candida isolates including C. albicans (n = 13), C. dubliniensis (n = 2), C. parapsilosis (n = 2), and C. tropicalis (n = 1); and reference strains of C. albicans (TIMML 1292 and TIMML 183), C. krusei (TIMML 1321), C. parapsilosis (TIMML 2201), and C. tropicalis (TIMML 731) were examined based on the M27-A3 guideline.ResultsAqueous and alcoholic extracts of Capsicum annum showed a minimum inhibitory concentration (MIC) range of more than 512 µg/ml against clinical and reference strains of Candida. There was no justifiable difference between the effects of these extracts on Candida species.ConclusionBoth aqueous and alcoholic extracts of Capsicum annum could not exert a significant effective impact on clinical and reference strains of Candida. The difference in pepper spiciness did not show a significant role against Candida isolates. However, their possible effects might be different among other yeasts or filamentous fungi.

Plant extracts-mediated green synthesis of zinc oxide/carbon nanofiber nanocomposites with highly efficient photocatalytic and antimicrobial properties for wastewater treatment

In the present study, a novel biosynthesis method for the preparation of zinc oxide/carbon nanofiber nanocomposite (ZnO-CNFs) is proposed along with evaluated their photocatalytic and antimicrobial properties for wastewater treatment. For biosynthesis of ZnO-CNFs, plant extracts of Thymus daenensis (TD) and Stachys pilifera Benth (SB) were used as both green-reducing agents and aqueous carbon-rich sources. The photocatalytic activity of the synthesized ZnO-CNFs was studied in the photodegradation of tetracycline antibiotic residues in contaminated water. The photocatalytic test (UVA irradiation, λ = 365 nm) results showed that the photodegradation efficiency of tetracycline by ZnO-CNFTD was 93.65 ± 2.1 %, 73.58 ± 1.5 %, 67.41 ± 1.7 %, and 81.28 ± 2.1 % in ultrapure water, infectious disease hospital 1, infectious disease hospital 2, and general hospital influents, respectively. Furthermore, the antimicrobial activity was examined against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria and Candida albicans (C. albicans) fungus. To this end, the antibacterial behaviors of ZnO-CNFs were studied based on minimal inhibitory concentration (MIC) ranges and diameter of inhibition zone, which indicated that the ZnO-CNFs exhibited superior antibacterial activity against Gram-positive (B. subtilis) and Gram-negative (E. coli) bacteria compared to ZnO nanoparticles. Also, the antifungal activity of ZnO-CNFTD with MIC range of 156.25–625 μg mL−1 was more potent than ZnO nanoparticles with MIC range of 156.25–2500 μg mL−1. Overall, our findings indicate that the synthesized ZnO-CNFTD exhibits excellent photocatalytic and antimicrobial potential compared to ZnO nanoparticles and therefore can be a promising candidate for effective treatment of water contaminated with microorganisms and organic compounds.

Reliable and rapid identification of terbinafine resistance in dermatophytic nail and skin infections.

Fungal infections are the most frequent dermatoses. The gold standard treatment for dermatophytosis is the squalene epoxidase (SQLE) inhibitor terbinafine. Pathogenic dermatophytes resistant to terbinafine are an emerging global threat. Here, we determine the proportion of resistant fungal skin infections, analyse the molecular mechanisms of terbinafine resistance, and validate a method for its reliable rapid identification. Between 2013 and 2021, we screened 5634 consecutively isolated Trichophyton for antifungal resistance determined by hyphal growth on Sabouraud dextrose agar medium containing 0.2 μg/mL terbinafine. All Trichophyton isolates with preserved growth capacity in the presence of terbinafine underwent SQLE sequencing. Minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. Over an 8-year period, the proportion of fungal skin infections resistant to terbinafine increased from 0.63% in 2013 to 1.3% in 2021. Our routine phenotypic in vitro screening analysis identified 0.83% (n = 47/5634) of Trichophyton strains with in vitro terbinafine resistance. Molecular screening detected a mutation in the SQLE in all cases. Mutations L393F, L393S, F397L, F397I, F397V, Q408K, F415I, F415S, F415V, H440Y, or A398 A399 G400 deletion were detected in Trichophyton rubrum. Mutations L393F and F397L were the most frequent. In contrast, all mutations detected in T. mentagrophytes/T. interdigitale complex strains were F397L, except for one strain with L393S. All 47 strains featured significantly higher MICs than terbinafine-sensitive controls. The mutation-related range of MICs varied between 0.004 and 16.0 μg/mL, with MIC as low as 0.015 μg/mL conferring clinical resistance to standard terbinafine dosing. Based on our data, we propose MIC of 0.015 μg/mL as a minimum breakpoint for predicting clinically relevant terbinafine treatment failure to standard oral dosing for dermatophyte infections. We further propose growth on Sabouraud dextrose agar medium containing 0.2 μg/mL terbinafine and SQLE sequencing as fungal sporulation-independent methods for rapid and reliable detection of terbinafine resistance.

Comparative bioactive compounds and antifungal potential evaluation of Mentha longifolia (L.) Hudson (Lamiaceae) extracts against plant pathogenic fungi

The present study was design to evaluate the Mentha longifolia stem, flower and leaves infusion, decoction and hydroalcoholic extracts to determine the bioactive molecules and antifungal activities by zone of inhibition technique, Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were assay by broth dilution technique and spore germination assay using Light Compound Microscope against plant pathogenic fungi (Fusarium oxysporum, Aspergillus parasiticus, Rhizoctonia solani and Alternaria alternata). The Mentha longifolia phytochemicals were found in the range flavonoids 3.8 - 2.4%, saponins were 5.6-3.4%, alkaloids 0.7-0.1% and total phenolic were 40-15 mg Gallic acid/g. The maximum zone of inhibition 23±1 mm and 22±1 mm were found by hydroalcoholic leaves extract against Fusarium oxysporum and Aspergillus parasiticus respectively. The MIC range of hydroalcoholic were 12.5-100 mg/mL, infusion were 25-100 mg/mL and decoction were 25-200 mg/mL. While MFC range of hydroalcoholic were 25-200 mg/mL, infusion were 50- 200 mg/mL and decoction were 50-200 mg/mL. Spore germination assay reaveled that increse in the extract concenetration decrese the spore germination. The results revealed that Mentha longifolia chemical composition might be build up as latent bio- fungicides against plant pathogenic fungi.

Evaluation of Antimicrobial Susceptibility Testing Performance of DL 96 System for Enterobacterales.

DL96 Microbial Identification/Antimicrobial Susceptibility Testing (ID/AST) System (Zhuhai DL, Guangdong, China) is one of the most commonly used commercial ID/AST System in China. This study aims to evaluate the performance of DL 96E for Antimicrobial Susceptibility Testing (AST) of 270 Enterobacterales isolates from Hainan general hospital using the broth microdilution method (BMD) as reference method. CLSI M52 criteria was followed when analyzing the evaluation results. Twenty antimicrobial agents were evaluated, and categorical agreement (CA) ranged from 62.8% to 96.5%. Imipenem had the lowest CA (63.9%) and highest very major errors (VME) (52.8%). A total of 103 carbapenem-resistant Enterobacterales were evaluated; DL 96E miss identified 22 isolates, including six carbapenemase-producing Enterobacteriaceae. DL 96E must adjust the Minimum Inhibitory Concentration (MIC) ranges of ciprofloxacin, levofloxacin, and piperacillin-tazobactam to cover Clinical and Laboratory Standards Institute (CLSI) breakpoints, adjust the formulation of some antimicrobial, such as imipenem, and increase the MIC detection range to cover the Quality control (QC) strains' MIC range.

Report of terbinafine resistant Trichophyton spp. in Italy: Clinical presentations, molecular identification, antifungal susceptibility testing and mutations in the squalene epoxidase gene.

Numerous reports of resistance to terbinafine in Trichophyton spp. from all over the world are arousing justified attention and concern. Point mutations in the gene that encodes the squalene epoxidase (SQLE) enzyme are responsible for these therapeutic resistances. Primary objective of the study was to describe first isolates of Trichophyton spp. resistant to terbinafine among the patients treated between September 2019 and June 2022 at the Dermatology Units of Ospedale Maggiore Policlinico and San Bortolo Hospital. Secondary objective was to study the resistance mechanism. Patients with confirmed Trichophyton spp. infection has been treated with systemic and topical terbinafine. Patients were then re-evaluated 12 weeks after the therapy. Patients with incomplete or absent response to terbinafine underwent a new skin scraping for direct mycological examination, new identification of dermatophyte species from culture and MALDI-TOF, molecular species identification, antifungal susceptibility testing and molecular analysis of SQLE gene. We identified five patients without clinical response to treatment with terbinafine. The DNA sequencing of the ITS region identified one Trichophyton rubrum and four Trichophyton indotineae. The T. rubrum strain showed minimum inhibitory concentration (MIC) (90% growth inhibition) of 4 mg/L for terbinafine. The four T. indotineae strains showed a MICs range of 0.25-4 mg/L for terbinafine. The analysis of the SQLE gene in the T. rubrum strain showed a nucleotide substitution generating a missense mutation (L393F). The SQLE gene sequencing in the T. indotineae strains showed a nucleotide substitution generating a missense mutation (F397L) in two strains, a nucleotide substitution L393S in one strain and a nucleotide substitution F415C in another strain. We report the first cases of terbinafine-resistant Trichophyton isolates in the Italian population. Solid antifungal management programs will be needed to promote more responsible use of antimycotics and preserve their therapeutic efficacy to control antifungal resistance.

Prevalence and molecular characteristics of polymyxin-resistant Enterobacterales in a Chinese tertiary teaching hospital.

Polymyxin-resistant Enterobacterales poses a significant threat to public health globally, but its prevalence and genomic diversity within a sole hospital is less well known. In this study, the prevalence of polymyxin-resistant Enterobacterales in a Chinese teaching hospital was investigated with deciphering of their genetic determinants of drug resistance. Polymyxin-resistant Enterobacterales isolates identified by matrix-assisted laser desorption were collected in Ruijin Hospital from May to December in 2021. Both the VITEK 2 Compact and broth dilution methods were used to determine polymyxin B (PMB) susceptibility. Polymyxin-resistant isolates were further characterized by molecular typing using PCR, multi-locus sequence typing, and sequencing of the whole genome. Of the 1,216 isolates collected, 32 (2.6%) across 12 wards were polymyxin-resistant (minimum inhibitory concentration (MIC) range, PMB 4-256 mg/ml, and colistin 4 ≥ 16 mg/ ml). A total of 28 (87.5%) of the polymyxin-resistant isolates had reduced susceptibility to imipenem and meropenem (MIC ≥ 16 mg/ml). Of the 32 patients, 15 patients received PMB treatment and 20 survived before discharge. The phylogenetic tree of these isolates showed they belonged to different clones and had multiple origins. The polymyxin-resistant Klebsiella pneumoniae isolates belonged to ST-11 (85.72%), ST-15 (10.71%), and ST-65 (3.57%), and the polymyxin-resistant Escherichia coli belonged to four different sequence types, namely, ST-69 (25.00%), ST-38 (25.00%), ST-648 (25.00%), and ST-1193 (25.00%). In addition, six mgrB specific mutations (snp_ALT c.323T>C and amino acid change p.Val8Ala) were identified in 15.6% (5/32) of the isolates. mcr-1, a plasmid-mediated polymyxin-resistant gene, was found in three isolates, and non-synonymous mutations including T157P, A246T, G53V, and I44L were also observed. In our study, a low prevalence of polymyxin-resistant Enterobacterales was observed, but these isolates were also identified as multidrug resistant. Therefore, efficient infection control measures should be implemented to prevent the further spread of resistance to last-line polymyxin therapy.

The Optimal Dosing Regimen of Super Bioavailable Itraconazole in Obesity: An Experimental Rat Model Study.

Background Obesity may alter tissue distribution and clearance of several drugs, especially lipophilic ones. Itraconazole, a lipophilic drug, has been recently introduced in a super-bioavailable formulation (SB-ITZ) for the treatment of dermatophytosis. Evidence regarding optimal dosing of SB-ITZ in obesity is lacking. A current experimental study was planned to analyze tissue concentrations of SB-ITZ at different doses in obese and non-obese rats. Materials and methods Thirty-six Wistar albino rats of either sex were divided into obese and non-obese rats equally. Further, rats in both categories were divided into three dosing groups. Group 1 received SB-ITZ 13 mg once daily in the morning, group 2 received SB-ITZ 13 mg in the morning and 6.5 mg in the evening, while Group 3 rats received SB-ITZ 13 mg twice daily, orally. Concentrations of SB-ITZ in the skin, serum, and fatty tissue were assessed in each group on days 7, 14, 21, and 28. Comparison of SB-ITZ concentrations in various tissues in obese and non-obese rats and inter-group comparison of tissue concentrations across the three dosing regimens was done at day 28 and expressed as Mean ± SD.36 Wistar rats were divided into obese and non-obese rats equally. Results At day 28, skin concentrations of SB-ITZ were 5.36±1.1, 8.9±1.7 and 10.13±1.7 µg/g in Groups 1, 2, and 3, respectively, in non-obese rats, which was statistically significant (p<0.05) than skin concentration of obese rats (2.72±0.6, 4.2±0.7 and 4.66±0.5 µg/g) for the corresponding dosing groups respectively. Skin concentration of SB-ITZ was statistically significant for Groups 2 and 3 as compared to Group 1. Still, no statistically significant difference was noted between Groups 2 and 3 in non-obese and obese rats. Fatty tissue concentration of SB-ITZ was comparable in all 3 dosing regimens in non-obese and obese rats. But on the intergroup comparison, a statistically significant difference was observed for Groups 2 and 3 against Group 1 (p<0.05). Increasing the dose of SB-ITZ increased serum concentration. In non-obese rats, a statistically significant difference was noted between Group 2 (74.33±6.6 ng/ml) and Group 1 (52.5±9.9 ng/ml); p<0.01 and also in Group 3 (81.33±6.8 ng/ml) against Group 1; p<0.01. Group 3 achieved significantly higher concentration than the other two groups in obese rats (Group 3; 72±5.3, Group 2; 60.5±4.3, and Group 1; 45±7 ng/ml; p<0.01). Conclusion Overall, skin, fatty tissue, and serum concentrations of SB-ITZ were higher in non-obese rats compared to obese rats in all three dosing groups. Moreover, skin and fatty tissue concentrations were proportionately higher than serum in all the groups in non-obese and obese rats. Though the skin concentration of non-obese rats was significantly higher than obese rats, skin concentration in obese rats was within the minimum inhibitory concentration (MIC) range, demonstrating the efficacy of all dosing regimens.

Modeling Antibiotic Concentrations in the Vicinity of Antibiotic-Producing Bacteria at the Micron Scale.

It is generally thought that antibiotics confer upon the producing bacteria the ability to inhibit or kill neighboring microorganisms, thereby providing the producer with a significant competitive advantage. Were this to be the case, the concentrations of emitted antibiotics in the vicinity of producing bacteria might be expected to fall within the ranges of MICs that are documented for a number of bacteria. Furthermore, antibiotic concentrations that bacteria are punctually or chronically exposed to in environments harboring antibiotic-producing bacteria might fall within the range of minimum selective concentrations (MSCs) that confer a fitness advantage to bacteria carrying acquired antibiotic resistance genes. There are, to our knowledge, no available in situ measured antibiotic concentrations in the biofilm environments that bacteria typically live in. The objective of the present study was to use a modeling approach to estimate the antibiotic concentrations that might accumulate in the vicinity of bacteria that are producing an antibiotic. Fick's law was used to model antibiotic diffusion using a series of key assumptions. The concentrations of antibiotics within a few microns of single producing cells could not reach MSC (8 to 16 μg/L) or MIC (500 μg/L) values, whereas the concentrations around aggregates of a thousand cells could reach these concentrations. The model outputs suggest that single cells could not produce an antibiotic at a rate sufficient to achieve a bioactive concentration in the vicinity, whereas a group of cells, each producing the antibiotic, could do so. IMPORTANCE It is generally assumed that a natural function of antibiotics is to provide their producers with a competitive advantage. If this were the case, sensitive organisms in proximity to producers would be exposed to inhibitory concentrations. The widespread detection of antibiotic resistance genes in pristine environments suggests that bacteria are indeed exposed to inhibitory antibiotic concentrations in the natural world. Here, a model using Fick's law was used to estimate potential antibiotic concentrations in the space surrounding producing cells at the micron scale. Key assumptions were that per-cell production rates drawn from the pharmaceutical manufacturing industry are applicable in situ, that production rates were constant, and that produced antibiotics are stable. The model outputs indicate that antibiotic concentrations in proximity to aggregates of a thousand cells can indeed be in the minimum inhibitory or minimum selective concentration range.

Antimicrobial resistance in topical treatments for microbial keratitis: protocol for a systematic review and meta-analysis

IntroductionThere is evidence for increased resistance against the antimicrobials used to treat keratitis. This review aims to provide global and regional prevalence estimates of antimicrobial resistance in corneal isolates and...

In vitro effect of the iron chelator deferiprone on the antimicrobial susceptibility and biofilms of Burkholderia pseudomallei

This study evaluated the effect of the iron chelator deferiprone (DFP) on antimicrobial susceptibility and biofilm formation and maintenance by Burkholderia pseudomallei. Planktonic susceptibility to DFP alone and in combination with antibiotics was evaluated by broth microdilution and biofilm metabolic activity was determined with resazurin. DFP minimum inhibitory concentration (MIC) range was 4–64 µg/mL and in combination reduced the MIC for amoxicillin/clavulanate and meropenem. DFP reduced the biomass of biofilms by 21 and 12% at MIC and MIC/2, respectively. As for mature biofilms, DFP reduced the biomass by 47%, 59%, 52% and 30% at 512, 256, 128 and 64 µg/mL, respectively, but did not affect B. pseudomallei biofilm viability nor increased biofilm susceptibility to amoxicillin/clavulanate, meropenem and doxycycline. DFP inhibits planktonic growth and potentiates the effect of β-lactams against B. pseudomallei in the planktonic state and reduces biofilm formation and the biomass of B. pseudomallei biofilms.

Effect of promethazine on biofilms of gram-positive cocci associated with infectious endocarditis

This study evaluated the antimicrobial activity of promethazine against Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus mutans and its effect on the antimicrobial susceptibility of biofilms grown in vitro and ex vivo on porcine heart valves. Promethazine was evaluated alone and in combination with vancomycin and oxacillin against Staphylococcus spp. and vancomycin and ceftriaxone against S. mutans in planktonic form and biofilms grown in vitro and ex vivo. Promethazine minimum inhibitory concentration range was 24.4-95.31 μg/mL and minimum biofilm eradication concentration range was 781.25-3.125 μg/mL. Promethazine interacted synergistically with vancomycin, oxacillin and ceftriaxone against biofilms in vitro. Promethazine alone reduced (p < 0.05) the CFU-counts of biofilms grown on heart valves for Staphylococcus spp., but not for S. mutans, and increased (p < 0.05) the activity of vancomycin, oxacillin and ceftriaxone against biofilms of Gram-positive cocci grown ex vivo. These findings bring perspectives for repurposing promethazine as adjuvant in the treatment of infective endocarditis.

The In vitro activity of carbapenems alone and in combination with β-lactamase inhibitors against difficult-to-treat mycobacteria; Mycobacterium tuberculosis, Mycobacterium abscessus, and Mycobacterium avium complex: A systematic review.

Difficult-to-treat mycobacterial infections are increasing globally. There is an urgent need of new treatment alternatives for multidrug-resistant Mycobacterium tuberculosis (MTB), as well as nontuberculous mycobacteria such as the Mycobacterium abscessus complex (MABC) and Mycobacterium avium complex (MAC). Recently, new carbapenems and combinations of carbapenems with β-lactamase inhibitors have become available, but activity data in vitro against mycobacteria are so far scarce. Therefore, we performed a systematic review collating the minimum inhibitory concentrations (MICs) of carbapenems, with or without a β-lactamase inhibitors for MTB, MABC, and MAC. The databases PubMed and Web of Science were searched for the relevant articles in English up until September 21, 2022. Screening of studies was performed by two independent reviewers. MIC data by recommended methods with at least five individual MICs were included. Data were reported as MIC range, MIC50, modal MIC, and/or histograms when individual MICs were available. The study protocol was registered at PROSPERO (CRD42021258537). After screening, a total of 75 studies with MIC data for carbapenems with or without β-lactamase inhibitors were included in the review. For MTB, the oral carbapenem tebipenem combined with the β-lactamase inhibitor clavulanic acid resulted in the most significant reduction of MICs. For MABC, the addition of avibactam to tebipenem resulted in a 64-fold reduction of modal MIC. Data were insufficient for the analysis of MAC. Carbapenems, and in particular the novel oral compound tebipenem, in combination with clavulanic acid for MTB and avibactam for MABC may be an untapped potential for difficult-to-treat mycobacterial infections.

In vitro antimicrobial activity of crude propolis extracts and fractions.

The search for antimicrobials in propolis presents a new dimension for addressing the problem of antimicrobial drug resistance. The aim of this study was to determine the antimicrobial activity of extracts of crude propolis collected from different regions in Ghana and their active fractions. The antimicrobial activity of the extracts, as well as that of the chloroform, ethyl acetate, and petroleum ether fractions of the active samples were determined using the agar well diffusion method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the most active fractions were determined. The various crude propolis extracts frequently produced zones of inhibition against Staphylococcus aureus (17/20) than Pseudomonas aeruginosa (16/20), and Escherichia coli (1/20) test isolates. Chloroform and ethyl acetate solvents produced fractions possessing greater antimicrobial activity than the petroleum ether fraction. The mean MIC range of the most active fractions was greatest for S. aureus (76.0 ± 34.8-48.0 ± 33.0mg/ml) than for P. aeruginosa (40.8 ± 33.3-30.4 ± 6.7mg/ml) and E. coli, as was the mean MBC. Propolis has antimicrobial potential, and hence should be exploited as an alternative for the treatment of bacterial infections.

Anti-staphylococcal and antibiotic-potentiating activities of botanicals from nine Cameroonian food plants towards multidrug-resistant phenotypes

Background: Staphylococcus aureus is a commensal and pathogenic bacterium responsible for both community and nosocomial infections, superficial or deep, and benign or lethal. Staphylococcus aureus is a commensal and pathogenic bacterium responsible for both community and nosocomial infections, superficial or deep, and benign or lethal. Because of its infectious potential and its ability to develop resistance to many antibiotics, staphylococcal infections remain the target of reinforced clinical surveillance. To contribute to the fight against resistant staphylococcal infections, the in vitro assessment of the anti-staphylococcal activity of methanol extracts (or botanicals) of nine food plants from Cameroon, Persea americana, Psidium guajava, Syzygium jambos, Vernonia amygdalina, Citrus sinensis, passiflora edulis, Carica papaya, Aframomum letestuanum, and Garcinia kola), as well as the effects of the association of some of these botanicals with antibiotics against resistant and multidrug-resistant staphylococci. Methods: The plant secondary metabolites were extracted by maceration in methanol; the microdilution method using the rapid para-Iodonitrotetrazolium chloride (INT) colorimetric method was applied to evaluate the antibacterial activities of the botanicals as well as the effects of combining these extracts with antibiotics. Results: The botanicals had a minimum inhibitory concentration (MIC) range of 64-2048 µg/mL on the 17 staphylococcal strains and isolates tested. Extracts from Aframomum letestuanum seeds and Psidium guajava leaves and bark had the broadest activity spectra, inhibiting the growth of 95% and 85% of the studied bacteria, respectively. In the presence of an efflux pump inhibitor, reserpine, methanol extracts from Syzygium jambos leaves, Psidium guajava bark and epicarp, and Afromomum letestuanum epicarp showed a considerable increase in their activity. Botanicals from the leaves of Syzygium jambos improved the activities of tetracycline, ceftriaxone, chloramphenicol, and ampicillin against more than 80% of the tested bacteria. Conclusion: The investigated pants, mostly Psidium guajava, Syzygium jambos, and Aframomum letestuanum could be used in the treatment of staphylococcal infections with multidrug-resistant phenotypes.

Analysis of Mannose-Binding Lectin Protein Levels and their MIC Profile in Patients with Dermatophytosis.

Analysis of Mannose-Binding Lectin Protein Levels and their MIC Profile in Patients with Dermatophytosis.

Integração PK/PD para determinação de doses intramusculares de cloxacilina sódica para infecções causadas por Staphylococcus spp em caprinos

ABSTRACT This study aims to determine therapeutic protocols of intramuscular sodium cloxacillin (IM) in goats with potential antibacterial effects against Staphylococcus spp. We constructed a pharmacokinetic (PK) model of IM, followed by a pharmacokinetic/pharmacodynamic integration (PK/PD). Simulations of different therapeutic protocols were then performed, with the doses ranging from 30 to100 mg/kg every 8, 12, or 24 hours. We calculated the probability to target attainment (PTA) of reach protocol's therapeutic according to the minimum inhibitory concentration (MIC) range of 0.06 to 4 μg/mL. The PK/PD index (PDT) used was "time above the MIC for 40% of the time" (T&gt;MIC ≥40%). Protocols with single administration per day were incapable of achieving PTA ≥ 90% for any of the estimated MICs. However, by decreasing the administration interval, the PTA was increased. Thus, from the dose of 50 mg/kg every 12 hours, a PTA≥ 90% for MICs ≤ 0.5 μg/mL was achieved, while the 30 mg/kg dose every 8 hours was able to achieve a PTA≥ 90% for MICs of 2 μg/mL. The results suggest using 30 mg/kg dose every 8 hours in clinical studies of agents with MICs ≤ 2μg/mL; Nevertheless, the practitioner should adjust the dose in severe patients.

Effect of post-synthesis betanin functionalized silver nanoparticles on the cellular oxidative mechanism and biofilm formation in Staphylococcus aureus

Eliciting oxidative stress and interference with biofilm formation by silver nanoparticles (AgNPs) comprise some of the postulated mechanisms of bacteria destruction. Plant extracts are commonly employed both as reducing agents and stabilizers of green-synthesized AgNPs. This yields a broad nanoparticle size distribution and unpredictable coating arising from diverse biomolecules and oxidation products in the final reaction mixture, which makes the comparison of different experiments exploiting green synthesised AgNPs as antimicrobial agents tricky. The current study synthesised citrate-capped silver nanoparticles (CtAgNPs) with a diameter of 37.9±8.6 nm functionalized via ligand exchange with betanin. Subsequently, the betanin silver nanoparticles (BtnAgNPs) ability to perturb the cellular oxidative stress defence mechanism of Staphylococcus aureus American Type Culture Collection (ATCC) 12600 and biofilm-forming properties were evaluated. Treatment with a minimum inhibitory concentration (MIC) of BtnAgNPs (12.5ppm) promoted reactive oxygen species accumulation and significantly reduced superoxide dismutase (SOD) and catalase activities. Furthermore, BtnAgNPs at sub-minimum inhibitory concentrations (SubMICs) to MIC range (0.39-12.5 ppm) inhibited the establishment of biofilms in a concentration-dependent manner. The study advocates for synthesis protocols that produce precise-sized nanoparticles followed by selective biomolecule functionalization for better antimicrobial efficacy comparative studies between AgNPs bearing different coatings in future experiments.