Minimum Inhibitory Concentration Levels Research Articles

The Value of in-vitro Local Ceftriaxone Interrupted Irrigation for Soft Tissue Autograft in Arthroscopic ACL Reconstruction

Background: Postoperative septic arthritis of the knee joint is an uncommon complication with serious consequences following anterior cruciate ligament reconstruction (ACLR). Systemic antibiotics received preoperatively and presoaking the soft tissue autograft with antibiotics result in a lower infection rate. Preoperative intravenous antibiotics may not be sufficient enough to reach minimum inhibitory concentration (MIC) levels due to poor vascularity of hamstring tendons in addition the harvested graft is prone to infection from skin flora. Aim of the study: To assess the efficacy of local antibiotic (ceftriaxone drug 1g.) solution diluted in (500 mL 0.9% sodium chloride N/S) for invitro interrupted irrigation of harvested soft tissue ACL graft as prophylaxis in reducing the infection rate during knee joint arthroscopic procedure. Patients and Methods: A Prospective comparative study of forty patients fit for arthroscopic anterior cruciate ligament reconstruction were enrolled in the study. The timeline period from April 2022 to July 2023.patients divided into (group A), twenty patients (received local ceftriaxone irrigation 1gm. solution diluted in 500 mL 0.9% NaCl for presoaking soft tissue autograft) and (Group B), twenty patients received (plain NaCl 0.9% ) only for irrigation of harvested graft. All patients in both groups received intravenous ceftriaxone at time of induction of anesthesia. Patients with history of injury more than 2years, open procedure, intravenous drug abuse, alcoholism steroid use, revision cases, and a prior history of infection in the knee were excluded from the study. Patients were followed postoperatively by clinical, laboratory, and imaging studies. The chi-square test was used for the comparison of categorical data. A student T-test and ANOVA were conducted to demonstrate the differences in postoperative inflammatory markers. Results: Presoaking of soft tissue autograft with ceftriaxone was performed in 20 patients (the study group), while 20 patients (the control group) were soaked only with plain N/S. In the control group, two patients (10%) developed postoperative infection after 2 weeks postoperatively, while no case developed infection in the study group. There was no statistically significant difference (p >0.05) between the study and control groups in terms of demographic characteristics, type of graft (p = 0.34), associated arthroscopic procedure (p = 0.35), and Lysholm score (p = 0.58). In the study group, there was a significant decrease in ESR (P = 0.01) after 4 weeks, Total lymphocyte count (p = 0.04), and Polymorphonuclear (p = 0.03) after 6 weeks postoperatively. Conclusion: Presoaking of hamstring autograft with ceftriaxone intraoperative may be alternative for other antibiotics in reducing rate of infection following arthroscopic anterior cruciate ligament reconstruction.

Pharmacokinetic analysis of ceftazidime and cefazolin in the treatment of continuous ambulatory peritoneal dialysis-related peritonitis

Objective Peritoneal dialysis-related peritonitis (PDRP) presents a significant challenge for nephrologists. Continuous intraperitoneal cefazolin and ceftazidime are recommended for the treatment of peritonitis. However, some pharmacokinetic studies have shown that doses of 15–20 mg/kg/d may not achieve sufficient therapeutic levels. In this study, we investigated the pharmacokinetics of ceftazidime and cefazolin in patients with continuous ambulatory peritoneal dialysis-related peritonitis and compared the pharmacokinetic characteristics between traditional and modified treatment groups. Methods From February 2017 to December 2019, 42 PDRP patients (17 males, 25 females; mean age: 50.7 ± 12.1 years; mean body weight: 60.9 ± 11.8 kg) were recruited for the study, all participants were anuric. Twenty patients were enrolled in the traditional group and treated with cefazolin (1.0 g) and ceftazidime (1.0 g) via intraperitoneal administration once daily for 14 days. Twenty-two patients were enrolled in the modified group and received the same dose of antibiotics twice daily for the initial five days, followed by once daily for the subsequent nine days. Serum and dialysate samples were collected after days 1, 2, 3, 5, 7, 10, and 14 and analyzed via liquid chromatography-mass spectrometry. Results In the traditional group, the highest and lowest serum concentrations of ceftazidime were 35.9 and 21.7 µg/mL, respectively. The highest concentration of cefazolin was 54.6 µg/mL on day 5 and the lowest concentration was 30.4 µg/mL on day 1. In the modified group, the highest and lowest serum concentrations of ceftazidime were 102.2 and 54.8 µg/mL, respectively. The highest concentration of cefazolin was 141.7 µg/mL and the lowest concentration was 79.8 µg/mL. All antibiotic concentrations were above the minimum inhibitory concentration (MIC) level (8 µg/mL of ceftazidime and 2 µg/mL of cefazolin) throughout the treatment period. However, on day 1, the concentration of ceftazidime in the third bag of dialysate effluent from the traditional group fell below the MIC level. Despite remaining above the MIC, cefazolin concentration was consistently lower in the third bag of dialysate effluent from the traditional group throughout the treatment period. Conclusions Intraperitoneal administration of cefazolin and ceftazidime at a dose of 1 g twice daily for 5 days and then once daily for the rest of the treatment period ensured adequate therapeutic levels of antibiotics for treating anuric PDRP patients.

Anti-infective Efficacy of Duloxetine against Catheter-Associated Urinary Tract Infections Caused by Gram-Positive Bacteria.

Catheter-associated urinary tract infections (CAUTIs) frequently occur following the insertion of catheters in hospitalized patients, often leading to severe clinical complications. These complications are exacerbated by biofilm-forming organisms such as Staphylococcus aureus, contributing to the emergence of multidrug-resistant (MDR) strains, which complicates treatment strategies. This study aims to investigate the antibacterial, antibiofilm, and antiadhesive properties of duloxetine against S. aureus in the context of CAUTI. Our findings demonstrate that duloxetine exhibits significant antibacterial activity, as evidenced by the agar diffusion method. A minimal inhibitory concentration (MIC) of 37.5 μg/mL was established using the microdilution method. Notably, duloxetine displayed inhibitory effects against biofilm formation on polystyrene surfaces up to its MIC level, as demonstrated by the crystal violet method. Intriguingly, the study also revealed that duloxetine could prevent biofilm formation at lower concentrations and reduce mature biofilms, as confirmed by scanning electron microscopy (SEM) and quantitative biofilm assays. Furthermore, duloxetine-coated silicone catheter tubes exhibited antibacterial properties against S. aureus in a bladder model, visualized by confocal laser scanning microscopy (CLSM) and corroborated through FDA and PI staining, highlighting noticeable morphological changes in S. aureus post-treatment. In conclusion, this study presents duloxetine as a promising alternative agent with antibacterial and antiadhesive properties against S. aureus in the prevention and management of CAUTI, warranting further exploration in the clinical setting.

The Comparisons of Phenotypic and Genotypic Resistance of Staphylococcus aureus Isolates Against β-lactam and Tetracycline Antibiotics

Staphylococcus aureus (S. aureus) is a Gram-positive bacteria that causes various diseases in humans and animals. Treatment of S. aureus infection generally uses antibiotics, but what happens is, S. aureus resistance to antimicrobial agents is an increasing global problem. This study aims to compare the phenotypic and genotypic characters of S. aureus from animals isolates against β-lactam and tetracycline antibiotics class. Determination of resistance characteristics of 8 S. aureus isolates was carried out phenotypically by Kirby Bauer and Minimum Inhibitory Concentration (MIC) methods, while genotypically by detecting the blaZ and tet genes. The results of the study showed a relationship between resistance genes and phenotypic test results using the Kirby Bauer and MIC methods. Isolates C, D, F, and TLK with resistance gene characters blaZ-, tetK-, and tetM- showed a sensitive interpretation of the results of the Kirby Bauer and MIC tests. On the other hand, DMG, J, PGT, and KRG isolates were resistant to one or two antibiotics tested, both phenotypic and genotypic (blaZ+, tetK+/tetM+). It found that the MIC levels of some respective isolates were relatively high, isolates J and KRG had an ampicillin MIC level of 32 μg/ml, while isolates J and PGT had 256 μg/ml for oxytetracycline. Although the identification of resistance genes and Kirby Bauer can determine the character of bacterial resistance, MIC determination is necessary to provide qualitative and quantitative information for the benefit of making therapeutic decisions and infection control strategies.

Optimizing extraction of Pelargonium sidoides roots: Impact of ethanol concentration on biological activity of extracts

Pelargonium sidoides DC. (Geraniaceae) is an important indigenous medicinal plant in South Africa, historically employed by various ethnic groups to treat respiratory and gastrointestinal ailments. The proprietary herbal tincture, Umckaloabo®, utilizes an ethanolic extract (EPs® 7630) from the roots of P. sidoides, and has demonstrated effectiveness in alleviating symptoms of respiratory infections.P. sidoides roots contain numerous highly oxygenated coumarins and phenolic metabolites, notably the marker compound umckalin. While Umckaloabo® is prepared using 11 % ethanol extraction, the South African commercial market predominantly employs 60 % ethanol extraction due to its consistent umckalin yield and antimicrobial activity. The effects of these extraction methods on chemical composition and in vitro pharmacological activity remain poorly understood.This study confirmed superior antibacterial and antifungal activity in the 60 % ethanol extracts prepared from six root samples compared to the 11 % ethanol extracts. MIC values for both Gram-negative and Gram-positive bacteria ranged from 0.078 to 2.5 mg/mL in the 60 % extracts. Remarkably, two of the root extracts exhibited excellent to very good activity against C. albicans and C. neoformans with MIC values of 0.039 and 0.078 mg/mL, respectively.A positive correlation was identified between total minimum inhibitory concentration (MIC) levels and polyphenol content, rather than umckalin levels. The influence of these extracts on the pro-inflammatory cytokine IL-6 was assessed. Both 60 % and 11 % root extracts of P. sidoides at 100 µg/mL significantly reduced IL-6 production, with the 60 % extracts demonstrating a more pronounced effect (p = 0.008).Statistical analysis revealed significant differences between 11 % and 60 % ethanol extractions in terms of average MIC overall, average Gram-negative MIC, average Gram-positive MIC, fungal MIC, and IL-6 levels. Extracts with higher polyphenol values exhibited superior antimicrobial activity and antioxidant potential, suggesting that polyphenol content may serve as a more reliable indicator of antimicrobial activity than umckalin levels. Additionally, polyphenol levels in the roots may vary with altitude and other environmental factors, warranting further research.

Hyphae-specific genes: Possible molecular targets for magnetic iron oxide nanoparticles alone and combined with visible light in Candida albicans

Candida albicans readily develops resistance to fluconazole. Magnetic iron oxide nanoparticles (denoted as MION) and antimicrobial photodynamic therapy are attracting attention as therapeutic agents. This study aims to investigate the inhibitory efficacy of MION alone and combined with visible light against C. albicans and expression analysis of hyphal wall protein 1 (HWP1) and agglutinin-like sequence 1 (ALS1) genes in C. albicans. Antifungal susceptibility testing, photodynamic activity assay, reactive oxygen species (ROS) production assay and gene expression analysis were determined in C. albicans treated with MION alone and combined with visible light. MION at 1 × minimum inhibitory concentration (MIC) level (500 μg/mL) exhibited antifungal activity against C. albicans isolates. Further, 1 × MIC levels of MION alone and combined with visible light displayed remarkable fungicidal effects at 24 and 48 h after treatment. The MION combined with visible light caused the highest levels of ROS production by all C. albicans isolates. The relative RT-PCR data showed significant downregulation of HWP1 and ALS1 genes which are the key virulence genes in C. albicans. Differences in gene expression of HWP1 and ALS1 were more significant in MION combined with visible light treatments than MION alone. Our study sheds a novel light on facile development of effective treatment of C. albicans especially fluconazole-resistant C. albicans infections. The hyphae-specific genes HWP1 and ALS1 could be probable molecular targets for MION alone and combined with visible light in C. albicans.

Mobe leaf (Artocarpus lakoocha Buch. Ham) ethanol extract’s antibacterial activity on Streptococcus mutans cell membrane leakage and biofilm formation: An in vitro study

Background: Using fixed orthodontic appliances inhibits oral hygiene, which can lead to the increased development of biofilms and Streptococcus mutans, a cariogenic bacterium that is well known for causing dental caries, derived from bacteria of the Streptococcus genus. In order to decrease biofilm and the degree of cariogenic bacteria in the oral cavity, a variety of herbal ingredients are used. Among these, mobe (Artocarpus lakoocha Buch. Ham) leaves are herbal ingredients with antibacterial properties. Purpose: This study aimed to investigate the antibacterial activity, antibiofilm, and leakage of DNA and protein from mobe leaves. Methods: The diffusion method was used to assess antibacterial activity and determine the minimum inhibitory concentration. The antibiofilm activity was evaluated with Ultraviolet–visible (UV-Vis) spectrophotometry (600 nm), using violet crystal staining. The detection of DNA and protein leakage was carried out by checking for absorbance values using the UV-Vis spectrophotometry (260 nm and 280 nm). An increase in the absorbance value in the measured cell indicated an increase in the level of cell content produced by the cell. One-way analysis of variance was used statistically analyze the results of this study (P < 0.05). Results: Mobe leaf (A. lakoocha) extract’s minimum inhibitory concentration level was 3.125 mg/ml, the effective concentration of ethanol extract for inhibiting biofilm formation was 3.125 mg/ml, and the effective concentration of ethanol extract that could cause DNA and protein leakage was 50 mg/ml. Conclusions: Mobe leaf extract has good MIC for S. mutans.

Identification and characterization of a novel chromosomal aminoglycoside 3'-O-phosphotransferase, APH(3')-Id, from Kluyvera intermedia DW18 isolated from the sewage of an animal farm.

Aminoglycosides, as important clinical antimicrobials, are used as second-line drugs for treating multidrug-resistant tuberculosis or combined with β-lactam drugs for treating severe infections such as sepsis. Aminoglycoside-modifying enzyme (AME) is the most important mechanism of aminoglycoside resistance and deserves more attention. The bacterium Kluyvera intermedia DW18 was isolated from the sewage of an animal farm using the conventional method. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs) of antimicrobials. A novel resistance gene was cloned, and the enzyme was expressed. The kinetic parameters were measured by a SpectraMax M5 multifunctional microplate reader. Bioinformatic analysis was performed to reveal the genetic context of the aph(3')-Id gene and its phylogenetic relationship with other AMEs. A novel aminoglycoside 3'-O-phosphotransferase gene designated aph(3')-Id was identified in K. intermedia DW18 and shared the highest amino acid identity of 77.49% with the functionally characterized aminoglycoside 3'-O-phosphotransferase APH(3')-Ia. The recombinant plasmid carrying the novel resistance gene (pMD19-aph(3')-Id/E. coli DH5α) showed 1,024-, 512-, 128- and 16-fold increased MIC levels for kanamycin, ribostamycin, paromomycin and neomycin, respectively, compared with the reference strain DH5α. APH(3')-Id showed the highest catalytic efficiency for ribostamycin [kcat/Km of (4.96 ± 1.63) × 105 M-1/s-1], followed by paromomycin [kcat/Km of (2.18 ± 0.21) × 105 M-1/s-1], neomycin [kcat/Km of (1.73 ± 0.20) × 105 M-1/s-1], and kanamycin [kcat/Km of (1.10 ± 0.18) × 105 M-1/s-1]. Three conserved functional domains of the aminoglycoside phosphotransferase family and ten amino acid residues responsible for the phosphorylation of kanamycin were found in the amino acid sequence of APH(3')-Id. No mobile genetic element (MGE) was discovered surrounding the aph(3')-Id gene. In this work, a novel aminoglycoside 3'-O-phosphotransferase gene designated aph(3')-Id encoded in the chromosome of the environmental isolate Kluyvera intermedia DW18 was identified and characterized. These findings will help clinicians select effective antimicrobials to treat infections caused by pathogens with this kind of resistance gene.

Application of Three Compounds Extracted from Cynodon dactylon against Streptococcus mutans Biofilm Formation to Prevent Oral Diseases.

Streptococcus mutans bacteria form a biofilm called plaque that causes oral diseases, including tooth decay. Therefore, inhibition of biofilm formation is essential to maintaining good oral health. The health and nutritional benefits of Cynodon dactylon are well documented, but very little is known about its use to treat against oral diseases. The aim of this study was to detect the adhesion strength of the S. mutans bacterial biofilm in 100 cases in the Rajshahi region and evaluate the inhibitory activity of different compound extracts of C. dactylon on the S. mutans bacterial biofilm by determining the composition of isolated compounds using phytochemical analysis. Nuclear magnetic resonance (NMR) spectroscopy confirmed that three specific compounds from C. dactylon were discovered in this study: 3,7,11,15 tetramethyl hexadec-2-4dien 1-o1, compound 3,7,11,15 tetramethylhexadec-2-en-1-o1 from phytol derivatives, and stigmasterol. Results indicated that the compound of 3,7,11,15-tetramethyl-hexadec-2-en-1-ol exhibited higher antibiofilm activities on S. mutans than those of the other compound extracts. A lower level of minimum inhibitory concentration was exposed by 3, 7, 11,15 tetramethyl hexadeca-2-en-1-o1 (T2) on S. mutans at 12.5 mL. In this case, the compound of 3,7,11,15 tetramethyl hexadec 2en-1-o1 was used, and patients showed a mean value and standard error reduced from 3.42 ± 0.21 to 0.33 ± 0.06 nm. The maximum inhibition was (80.10%) in the case of patient no. 17, with a value of p < 0.05 found for S. mutans to which 12.5 μL/mL ethyl acetate extract was applied. From these findings, it may be concluded that C. dactylon extracts can be incorporated into various oral preparations to prevent tooth decay.

Comparative study of the antibacterial and anti-inflammatory activities of the seed coat vs. seed kernel extracts from the plant Mangifera indica L. in inflammatory acne treatment

Introduction: The present study was developed to investigate and compare the extraction yield, the contents of polyphenols and mangiferin, the activities against Propionibacterium acnes, Staphylococcus aureus, and Escherichia coli bacteria, and the anti-inflammatory activities of ethanol extracts of mango seed kernels vs. seed coats. Methods: Mango seed kernels and seed coats were extracted using ethanol as the solvent and tested against microorganisms using the disc diffusion method. The minimum inhibitory concentration (MIC) levels of extracts were determined by the agar dilution method. The anti-inflammatory activities were assessed both in vitro and in vivo by albumin denaturation method and carrageenan-induced paw edema test, respectively. Results: Both extracts yielded high contents of mangiferin and phenolic compounds. The antibacterial activities of both extracts showed inhibition of the tested microorganisms Propionibacterium acnes and Staphylococcus aureus but not Escherichia coli. Seed kernel extract (0.2 g/kg) reduced paw edema by 44.8% at 3 hours after λ-carrageenan administration. Meanwhile, 0.5 g/kg seed coat extract reduced paw edema less than the seed kernel extract (23.1% vs. 44.8%). Mango seed kernel extract, mango seed coat extract, and diclofenac sodium displayed concentration-dependent inhibition of heat-induced protein denaturation with IC50 values of 137.23 μg/mL, 292.12 μg/mL, and 6.64 μg/mL, respectively. Conclusion: The obtained results confirmed the antibacterial and anti-inflammatory potential of mango seed kernel and seed coat extracts. The mango seed kernel extract was proven to be more effective than the mango seed coat extract and thus can be used in cosmetics as an anti-inflammatory and antibacterial agent.

Investigation of efflux pump genes in isoniazid resistant Mycobacterium tuberculosis isolates

BackgroundTuberculosis (TB) is one of the most important infectious diseases worldwide. Resistance to antituberculosis drugs develops because of genetic mutations that render drug-activating enzymes inactive, changes in cell wall permeability, and increased expression of efflux pump genes and also combination therapy with efflux pump inhibitors may be more effective in drug-resistant TB patients. AimsTo investigate the effect of verapamil (VR) on isonicotinic acid hydrazide (INH) resistance and the expression of 21 efflux pump genes in INH monoresistant MTBC clinical isolates. Study designIn vitro study. MethodsIn our mycobacteriology laboratory, 10 INH monoresistant and 10 primary anti-TB drug-susceptible MTBC clinical isolates were selected. Drug susceptibilities for INH and VR were studied by resazurin microtiter plate method and minimum inhibitory concentration (MIC) was determined. Additionally, mRNA gene expressions were investigated by quantitative Real Time Polymerase Chain Reaction for 21 efflux gene regions. ResultsWhile no change was observed in INH MICs of susceptible isolates under VR effect, 6 (60%) of the 10 INH-resistant isolates showed a decrease of less than one dilution in INH MIC under VR effect. VR significantly reduced resistance in resistant isolates (p ​< ​0.05). INH monoresistant MTBC isolates showed a 2.85-fold expression increase in the Rv1634 region of the Major Facilitator Superfamily efflux family under INH stress (p ​= ​0.029). No statistically significant change was observed in other efflux gene regions. Herein, increased expression was observed in the Rv1634 region, consistent with other studies in the literature, and this was associated with drug resistance. No significant change in expression was detected in other gene regions. ConclusionThe effect of efflux pump inhibitor VR on INH MIC levels is promising for the treatment of resistant TB. However, studies with more resistant strains are needed to evaluate the efficacy of efflux pump genes.

Transferable mechanisms of quinolone resistance are more frequent among enterotoxigenic Escherichia coli isolates displaying low-level quinolone resistance.

This study analysed the mechanisms of quinolone resistance among enterotoxigenic Escherichia coli (ETEC) in a periurban area of Lima, Peru. The susceptibility to nalidixic acid and ciprofloxacin, the role of Phe-Arg-b-Naphtylamyde inhibitable-(PAbN) efflux pumps, the presence of mutations in gyrA and parC as well as the presence of aac(6')Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD, qnrVC and oqxAB were determined in 31 ETEC from previous case/control studies of children's diarrhoea. Discordances between disk diffusion, with all isolates showing intermediate or fully resistance to nalidixic acid, and minimal inhibitory concentration (MIC), with 7 isolates being below considered resistance breakpoint, were observed. Twenty-one isolates possessed gyrA mutations (19 S83L, 2 S83A). AAC(6') Ib-cr, QnrS, QnrB and QepA were found in 7, 6, 2 and 1 isolates respectively, with 3 isolates presenting 2 transferable mechanisms of quinolone resistance (TMQR) concomitantly. TMQR were more frequent among isolates with MIC to nalidixic acid ranging from 2 to 16 mg/L (p=0.03), while gyrA mutations were more frequent among isolates with nalidixic acid MIC >= 128 mg/L (p=0.0002). In summary, the mechanisms of quinolone resistance present in ETEC isolates in Peru have been described. Differences in the prevalence of underlying mechanisms associated with final MIC levels were observed. The results suggest two different evolutive strategies to survive in the presence of quinolones related to specific bacterial genetic background.

Identification and characterization of a novel aminoglycoside O-nucleotidyltransferase ANT(6)-If from Paenibacillus thiaminolyticus PATH554.

Paenibacillus thiaminolyticus, a species of genus Paenibacillus of the family Paenibacillaceae, exists widely in environments and habitats in various plants and worms, and occasionally causes human infections. This work aimed to characterize the function of a novel aminoglycoside O-nucleotidyltransferase resistance gene, designated ant(6)-If, from a P. thiaminolyticus strain PATH554. Molecular cloning, antimicrobial susceptibility testing, enzyme expression and purification, and kinetic analysis were used to validate the function of the novel gene. Whole-genome sequencing and comparative genomic analysis were performed to investigate the phylogenetic relationship of ANT(6)-If and other aminoglycoside O-nucleotidyltransferases, and the synteny of ant(6)-If related sequences. The recombinant with the cloned ant(6)-If gene (pMD19-ant(6)-If/DH5α) demonstrated a 128-fold increase of minimum inhibitory concentration level against streptomycin, compared with the control strains (DH5α and pMD19/DH5α). The kinetic parameter kcat/Km of ANT(6)-If for streptomycin was 9.01 × 103 M-1·s-1. Among the function-characterized resistance genes, ANT(6)-If shared the highest amino acid sequence identity of 75.35% with AadK. The ant(6)-If gene was located within a relatively conserved genomic region in the chromosome. ant(6)-If conferred resistance to streptomycin. The study of a novel resistance gene in an unusual environmental bacterium in this work contributed to elucidating the resistance mechanisms in the microorganisms.

Non-Antibiotic Compounds Synergistically Kill Chronic Wound-Associated Bacteria and Disrupt Their Biofilms.

Chronic wounds and their treatment present a significant burden to patients and healthcare systems alike, with their management further complicated by bacterial infection. Historically, antibiotics have been deployed to prevent and treat infections, but the emergence of bacterial antimicrobial resistance and the frequent development of biofilms within the wound area necessitates the identification of novel treatment strategies for use within infected chronic wounds. Here, several non-antibiotic compounds, polyhexamethylene biguanide (PHMB), curcumin, retinol, polysorbate 40, ethanol, and D-α-tocopheryl polyethylene glycol succinate 1000 (TPGS) were screened for their antibacterial and antibiofilm capabilities. The minimum inhibitory concentration (MIC) and crystal violet (CV) biofilm clearance against two bacteria frequently associated with infected chronic wounds, Staphylococcus aureus and Pseudomonas aeruginosa, were determined. PHMB was observed to have highly effective antibacterial activity against both bacteria, but its ability to disperse biofilms at MIC levels was variable. Meanwhile, TPGS had limited inhibitory activity but demonstrated potent antibiofilm properties. The subsequent combination of these two compounds in a formulation resulted in a synergistic enhancement of their capability to kill both S. aureus and P. aeruginosa and disperse their biofilms. Collectively, this work highlights the utility of combinatory approaches to the treatment of infected chronic wounds where bacterial colonization and biofilm formation remains significant issues.

Design, Development, and Evaluation of Constant Voltage Iontophoresis for the Transungual Delivery of Efinaconazole.

The efficacy of topical antifungal therapy in onychomycosis has been hindered by the failure of the antimycotic to permeate the nail plate. This research aims to design and develop a transungual system for the effective delivery of efinaconazole utilizing constant voltage iontophoresis. Seven prototype drug-loaded hydrogel formulations (E1-E7) were prepared to assess the influence of solvent (ethanol) and cosolvent (Labrasol®) on transungual delivery. Optimization was performed to evaluate the effect of three independent variables; voltage, solvent-to-cosolvent ratio, and penetration enhancer (PEG 400) concentration on critical quality attributes (CQAs), such as drug permeation and loading into the nail. The selected hydrogel product was characterized for pharmaceutical properties, efinaconazole release from the nail, and antifungal activity. Preliminary data indicates ethanol, Labrasol®, and voltage influence the transungual delivery of efinaconazole. Optimization design indicates a significant impact by applied voltage (p-0.0001) and enhancer concentration (p-0.0004) on the CQAs. Excellent correlation between selected independent variables and CQAs was confirmed by the high desirability value (0.9427). A significant (p < 0.0001) enhancement in the permeation (~78.59 µg/cm2) and drug loading (3.24 µg/mg) was noticed in the optimized transungual delivery with 10.5 V. FTIR spectral data indicates no interaction between the drug and excipients, while the DSC thermograms confirmed the amorphous state of the drug in the formulation. Iontophoresis produces a drug depot in the nail that releases above the minimum inhibitory concentration level for an extended period, potentially reducing the need for frequent topical treatment. Antifungal studies further substantiate the release data and have shown remarkable inhibition of Trichophyton mentagrophyte. Overall, the promising results obtained here demonstrate the prospective of this non-invasive method for the effective transungual delivery of efinaconazole, which could improve the treatment of onychomycosis.

The First Report of Chryseobacterium gleum Caused Ventriculoperitoneal-shunt Infection in a Child.

To The Editors: Ventriculoperitoneal (VP) shunt is one of the most widely used and effective methods in the treatment of hydrocephalus in childhood. VP shunt infections have been observed in approximately 3.2%–25%, and Chryseobacterium spp. is a rare cause of VP shunt infections.1,2 Herein, we report the first VP shunt infection caused by Chryseobacterium gleum. A 12-month-old female (corrected age 8 months) born via spontaneous vaginal delivery, weighed 700 g at 25 weeks of gestation, was admitted to our emergency department with a fever with a maximum peak temperature of 39°C, projectile vomiting, and decreased oral intake. Her history included long-term ventilation in the neonatal intensive care unit with a diagnosis of moderate bronchopulmonary dysplasia. At 4 months of age, she developed intraventricular hemorrhage and progressive hydrocephalus, and a VP shunt was inserted. She had several episodes of VP shunt infections caused by S. epidermidis and S. aureus. At admission, the patient was febrile, tachycardic (heart rate, 160/min) and tachypneic (respiratory rate of 48/min). Physical examination showed weakness, lethargy and sleepiness. Her total Glasgow Coma Scale score was 12 (E3V4M5). Laboratory tests were as follows: white blood cell (WBC) count: 12.5 × 103/μL (neutrophil 37% and lymphocyte 54%), C-reactive protein: 20 mg/L, procalcitonin: 0.09 μg/L. The cerebrospinal fluid (CSF) WBC count was 120/mm3, protein 107 mg/dL and glucose 42 mg/dL. With the preliminary diagnoses of sepsis and shunt infection, intravenous (IV) cefotaxime (300 mg/kg/day) and IV vancomycin (60 mg/kg/day) was initiated empirically. Peripheral/catheter blood cultures and CSF samples were inoculated into aerobic and anaerobic culture bottles (BacT/ALERT, BioMérieux, Durham, USA). The patient underwent VP shunt externalization. The blood and urine cultures were negative during the patient’s follow-up. Chryseobacterium gleum was isolated in the CSF, shunt and ventricular catheter tip cultures on the 3rd day of treatment. The organism had high-level minimum inhibitory concentration (MIC) levels for meropenem (MIC = 32 μg/mL), imipenem (MIC = 32 μg/mL) and piperacillin-tazobactam (MIC = 250 μg/mL). MIC level of ciprofloxacin was 0.125 μg/mL and trimethoprim-sulfamethoxazole was 0.5 μg/mL. Cefotaxime and vancomycin were switched to IV trimethoprim/sulphamethoxazole (5 mg/kg every 6 hours) and ciprofloxacin (10 mg/kg every 8 hours). On the 5th day of the combined therapy, the patient’s CSF sample was evaluated and showed a WBC count of 30/mm3, glucose 42 mg/dL and protein 360 mg/ dL, and the CSF culture was sterile. Antibiotics were continued for 21 days. The patient was clinically stable, and no adverse effects or seizures were observed during or after the treatment. The extra ventricular drainage was removed, the VP shunt was inserted following 2 consecutive negative CSF cultures, and the patient was discharged. Chryseobacterium species are common in nature but are not found in human flora. Most cases are nosocomial and are frequently associated with immunosuppression or implantable devices. Chryseobacterum gleum is typically a low-virulence organism that can cause serious infections. It has been reported that Chryseobacterum gleum can cause infections such as central-line-associated bloodstream infection, community-acquired pneumonia and urinary tract infection in adults.3–5 Unlike previous reports, Chryseobacterium was isolated in the cerebrospinal fluid in our study. Chryseobacterum gleum commonly colonizes mechanical devices, causing device-associated infections, and can form biofilm. According to this study, VP shunt may be a risk factor for Chryseobacterium gleum infections. This report emphasizes the significance of Chryseobacterium species as a causative agent of a wide range of infections, and VP shunts can pose a risk for this agent. Data on the management of Chryseobacterium is limited. Antimicrobial susceptibility testing guidelines for Chryseobacterium infections should be developed for more effective and accurate treatment.

Biosynthesis of silver nanoparticles using Pseudomonas canadensis, and its antivirulence effects against Pseudomonas tolaasii, mushroom brown blotch agent

This study reports the biosynthesis of silver nanoparticles (AgNPs) using a Pseudomonas canadensis Ma1 strain isolated from wild-growing mushrooms. Freshly prepared cells of P. canadensis Ma1 incubated at 26–28 °C with a silver nitrate solution changed to a yellowish brown color, indicating the formation of AgNPs, which was confirmed by UV–Vis spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction. SEM analysis showed spherical nanoparticles with a distributed size mainly between 21 and 52 nm, and the XRD pattern revealed the crystalline nature of AgNPs. Also, it provides an evaluation of the antimicrobial activity of the biosynthesized AgNPs against Pseudomonas tolaasii Pt18, the causal agent of mushroom brown blotch disease. AgNPs were found to be bioactive at 7.8 μg/ml showing a minimum inhibitory concentration (MIC) effect against P. tolaasii Pt18 strain. AgNPs at the MIC level significantly reduced virulence traits of P. tolaasii Pt18 such as detoxification of tolaasin, various motility behavior, chemotaxis, and biofilm formation which is important for pathogenicity. Scanning electron microscopy (SEM) revealed that bacterial cells treated with AgNPs showed a significant structural abnormality. Results showed that AgNPs reduced brown blotch symptoms in vivo. This research demonstrates the first helpful use of biosynthesized AgNPs as a bactericidal agent against P. tolaasii.

Efflux pump effects on Mycobacterium tuberculosis drug resistance

Resistance and tolerance to antituberculosis drugs have become serious problems in disease treatment. This multi-phase study investigated the contributions of efflux pumps to Mycobacterium tuberculosis drug resistance. In the first phase, the minimum inhibitory concentration (MIC) levels of antibiotics were determined. In the second phase, MIC levels were determined in the presence of the efflux pump inhibitors carbonyl cyanide m-chlorophenyl hydrazone (CCCP), verapamil, reserpine and thioridazine. In the third phase, MIC levels were reduced in 6 M. tuberculosis isolates in the presence of efflux pump inhibitors to determine the expression of putative efflux pump genes by reverse transcriptase-polymerase chain reaction (RT-PCR). MIC levels of fluoroquinolones decreased in 6 (6.52%) isolates, MIC of rifampicin in 4 (4.34%), and MIC of streptomycin in 3 (3.26%) in the presence of efflux pump inhibitors reserpine, CCCP and verapamil. The efflux pump inhibitors CCCP, verapamil, and reserpine changed MICs 2- to 16-fold. Overexpression of all 15 efflux pump genes was observed in 6 isolates with a reduction in MIC values in the presence of efflux pump inhibitors. The overexpression of efflux-related genes in resistant isolates suggests that efflux pumps are associated with resistance development.

Functional characterization of a novel aminoglycoside phosphotransferase, APH(9)-Ic, and its variant from Stenotrophomonas maltophilia.

The intrinsic resistance mechanism plays an essential role in the bacterial resistance to a variety of the antimicrobials. The aim of this study is to find the chromosome-encoded novel antimicrobial resistance gene in the clinical isolate. The function of the predicted resistance gene was verified by gene cloning and antibiotic susceptibility test. Recombinant protein expression and enzyme kinetic studies were performed to explore the in vivo activity of the enzyme. Expression of the resistance gene exposed to antimicrobial was determined by RT-qPCR. Whole genome sequencing and bioinformatic analysis were applied to analyze the genetic context of the resistance gene. The novel aminoglycoside (AG) resistance genes designated aph(9)-Ic and aph(9)-Ic1 confer resistance to spectinomycin, and a recombinant strain harboring aph(9)-Ic (pMD19-T-aph(9)-Ic/DH5α) showed a significantly increased minimum inhibitory concentration (MIC) level against spectinomycin compared with the control strains (DH5α and pMD19-T/DH5α). The result of the kinetic analysis of APH(9)-Ic was consistent with the MIC result for the recombinant pMD19-T-aph(9)-Ic/DH5α, showing the efficient catalytic activity for spectinomycin [kcat/Km ratio = (5.58 ± 0.31) × 104 M-1·s-1]. Whole-genome sequencing demonstrated that the aph(9)-Ic gene was located on the chromosome with a relatively conserved genetic environment, and no mobile genetic element was found in its surrounding region. Among all the function-characterized resistance genes, APH(9)-Ic shares the highest amino acid sequence identity of 33.75% with APH(9)-Ia. We characterized a novel AG resistance gene aph(9)-Ic and its variant aph(9)-Ic1 that mediated spectinomycin resistance from S. maltophilia. The identification of the novel AG resistance genes will assist us in elucidating the complexity of resistance mechanisms in microbial populations.

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.