Gram-positive Research Articles

Gram Positive Cocci Associated Urinary Tract Infections, their Prevalence and Antibiotic Susceptibility Patterns

Background: Urinary tract infections (UTIs) are the third most common type of infection in humans globally. Gram-positive bacteria are said to be responsible for ten percent of urinary tract (UTI) infections. The study's goal was to profile gram-positive cocci-associated UTIs and their antibiogram, as they were observed at LASUTH. Methods: This was a retrospective assessment of the Medical Microbiology Laboratory records of the LASUTH to review the in vitro antibiotic susceptibility patterns of gram-positive urinary bacterial isolates between April 2020 and March 2021. The bacteria were isolated and identified from routine urine samples using standard bacteriological methods and the API. In vitro antibiotic susceptibility test (AST) was routinely performed by the modified Kirby-Bauer disk diffusion test and susceptibility breakpoints were determined using the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: 2,253 urine samples were processed in the medical microbiology laboratory over the one year and 662 (29.4%) samples yielded Positive cultures. Of the 662 isolates, 494 (74.6%) were gram-negative bacteria. 164 (24.8%) were gram-positive cocci while 4 (0.6%) were gram positive rod. Among the gram-positive cocci’s isolated Enterococcus faecalis had the highest frequency 58 (35.4%). Aminoglycosides (Gentamycin and Amikacin) and Linezolid antibiotics were found to be the most effective drugs against gram-positive cocci bacteria except Enterococcus spp. For empirical treatment of Enterococcus spp in our facility Fosfomycin and Tigecycline are the best options, while for Streptococcus agalactiae associated UTI, Amikacin, Cefuroxime, Linezolid, and levofloxacin can be used for empirical treatment. Conclusion: The prevalence rate of gram-positive cocci associated UTI in this study was 7.3% (164/2253). The emergence of drug resistance in these pathogens to commonly used antibiotics is a thing of concern. Therefore, efficient antimicrobial stewardship programmes must be in place.

Antibacterial activity of pimaradienoic acid from Eleutherococcus trifoliatus (L.) S. Y. Hu.

Purpose: To investigate the antibacterial activity of pimaradienoic acid, a natural product isolated from Eleutherococcus trifoliatus. Methods: Pimaradienoic acid was purified from E. trifoliatus and tested against three Gram-positive bacteria. Minimum inhibitory concentrations (MICs) were determined, and bacterial growth curves were measured. Scanning electron microscopy (SEM) was used to observe morphological changes in bacteria after drug treatment. Results: Pimaradienoic acid exhibited concentration-dependent inhibition of the growth of the three bacteria tested. The MIC and bacterial growth dynamics results indicated that pimaradienoic acid had potent antibacterial activity. SEM revealed that pimaradienoic acid disrupted the bacterial membrane, leading to cell death. Conclusions: Pimaradienoic acid has significant antibacterial activity against Gram-positive bacteria, suggesting its potential as a novel antimicrobial agent.

A novel family of defensin-like peptides from Hermetia illucens with antibacterial properties.

The world faces a major infectious disease challenge. Interest in the discovery, design, or development of antimicrobial peptides (AMPs) as an alternative approach for the treatment of bacterial infections has increased. Insects are a good source of AMPs which are the main effector molecules of their innate immune system. Black Soldier Fly Larvae (BSFL) are being developed for large-scale rearing for food sustainability, waste reduction and as sustainable animal and fish feed. Bioinformatic studies have suggested that BSFL have the largest number of AMPs identified in insects. However, most AMPs identified in BSF have not yet undergone antimicrobial evaluation but are promising leads to treat critical infections. Jg7197.t1, Jg7902.t1 and Jg7904.t1 were expressed into the haemolymph of larvae following infection with Salmonella enterica serovar Typhimurium and were predicted to be AMPs using the computational tool ampir. The genes encoding these proteins were within 2 distinct clusters in chromosome 1 of the BSF genome. Following removal of signal peptides, predicted structures of the mature proteins were superimposed, highlighting a high degree of structural conservation. The 3 AMPs share primary sequences with proteins that contain a Kunitz-binding domain; characterised for inhibitory action against proteases, and antimicrobial activities. An in vitro antimicrobial screen indicated that heterologously expressed SUMO-Jg7197.t1 and SUMO-Jg7902.t1 did not show activity against 12 bacterial strains. While recombinant SUMO-Jg7904.t1 had antimicrobial activity against a range of Gram-negative and Gram-positive bacteria, including the serious pathogen Pseudomonas aeruginosa. We have cloned and purified putative AMPs from BSFL and performed initial in vitro experiments to evaluate their antimicrobial activity. In doing so, we have identified a putative novel defensin-like AMP, Jg7904.t1, encoded in a paralogous gene cluster, with antimicrobial activity against P. aeruginosa.

Chemical Composition of Turmeric (Curcuma longa L.) Ethanol Extract and Its Antimicrobial Activities and Free Radical Scavenging Capacities.

Turmeric (Curcuma longa L.) is a perennial tuberous plant from the genus Curcuma (Zingiberaceae) and has been widely used in foods for thousands of years. The present study examined the ethanol extract of turmeric for its chemical composition, antimicrobial activity, and free radical scavenging properties. UHPLC-MS/MS analysis tentatively identified eight compounds in the turmeric extract. Potential antimicrobial effects of 0.1, 1.0, and 10 mg turmeric equivalents (TE)/mL were evaluated in vitro against a variety of Gram-negative bacteria (i.e., Escherichia coli, Klebsiella pneumoniae, and Pseudomonas sp.) and Gram-positive bacteria (i.e., Enterococcus faecalis, Listeria innocua, and Staphylococcus aureus). Concentrations of 0.1 and 1.0 mg TE/mL inhibited the growth of S. aureus and significantly suppressed that of Pseudomonas sp., E. faecalis, and L. innocua. The growth of all strains, including E. coli, was inhibited by 10 mg TE/mL. Moreover, free radical scavenging capacities were determined using HO●, ABTS●+, and DPPH● (HOSC, ABTS, and RDSC, respectively) radicals. The turmeric ethanol extract had a TPC value of 27.12 mg GAE/g, together with HOSC, RDSC, and ABTS values of 1524.59, 56.38, and 1.70 μmol TE/g, respectively. Our results suggest that turmeric extract has potential applications for use in functional foods to reduce microbial burdens and oxidative stress-related health problems.

Bullet-related bacterial wound infections among injured personnel at emergency site hospitals in Bahir Dar: prevalence, antimicrobial susceptibility and associated factors.

Bullet-related bacterial wound infection can be caused by high-velocity bullets and shrapnel injuries. In Ethiopia, significant injuries were reported that may cause severe wound infections, persistent systemic infections and may lead to amputation and mortality. The magnitude, antimicrobial susceptibility profiles, and factors associated with bacterial wound infections among patients with bullet-related injuries are not yet studied particularly at health facilities in Bahir Dar, Northwest Ethiopia. Therefore, this study was aimed to determine the prevalence, bacterial profiles, antimicrobial susceptibility profiles, and factors associated with bacterial infections among patients with bullet-related injuries at referral health facilities in Bahir Dar, Northwest Ethiopia. A Hospital-based cross-sectional study was conducted among patients with bullet-related injuries at three referral health facilities in Bahir Dar from May 25 to July 27, 2022. A total of 384 patients with bullet-related injuries were included in the study. Sociodemographic and clinical data were collected using a structured questionnaire. Wound swabs were collected aseptically and cultured on Blood and MacConkey agar following bacteriological standards. Biochemical tests were performed to differentiate bacteria for positive cultivation and antimicrobial susceptibility profiles of the isolates were done on Muller Hinton agar using the Kirby-Bauer disk diffusion technique according to the 2021 Clinical Laboratory Standard Institute (CLSI) guideline. The data were entered using Epi-Info version 7.3 and analyzed using SPSS version 25. Descriptive data were presented using frequency, percentages, figures, and charts. Logistic regression was carried out to identify factors associated with bacterial wound infections. P-value < 0.05 was considered statistically significant. The prevalence of bullet-related bacterial wound infection among three referral hospitals in Bahir Dar city was 54.7%. The most commonly isolated Gram-negative organism was Klebsiella spps 49 (23.3%) while among Gram-positive organism, Staphylococcus aureus 58 (27.6%) and coagulase-negative staphylococci (CONS) 18 (8.6%). Contamination, hospitalization and smoking habit were significantly associated with the presence of bullet-related bacterial wound infections. Over 97% multidrug resistant (MDR) bacterial isolates were identified and of theses, E. coli, Proteus species, Citrobactor, and Staphylococcus aureus were highly drug resistant. Increased prevalence of bullet-related bacterial wound infection was noticed in this study. S. aureus followed by Klebsiella species were most commonly isolated bacteria. High frequency of resistance to Ampicillin, Oxacillin, Cefepime, Ceftriaxone, Ceftazidime, Vancomycin, and Norfloxacin was observed. Therefore, proper handling of bullet injuries, prompt investigation of bacterial infections, monitoring of drug sensitivity patterns and antibiotic usage are critical.

Isolation of a Marker Olean-12-en-28-butanol Derivative from Viscum continuum E. Mey. Ex Sprague and the Evaluation of Its Antioxidant and Antimicrobial Potentials.

Viscum continuum E. Mey. Ex Sprague (Mistletoe) is a semi-parasitic plant that grows on the branches of other trees with reported numerous biological activities. This study was aimed at isolating a compound/s that will be used as a standard reference for quality control of South African-based commercialized mistletoe products and to further perform antioxidant and antimicrobial tests on the isolated compound. A dried sample of mistletoe was ground and extracted successively with hexane, dichloromethane (DCM), acetone and methanol using a serial exhaustive cold maceration procedure. The compound was isolated using column chromatography, and its chemical structure was elucidated using two-dimensional nuclear magnetic resonance (2D NMR) and ultrahigh-performance liquid chromatography-mass spectrometry (UPLC-MS). The antioxidant activity of the compound was determined using DPPH, hydrogen radical scavenging activity and reducing power assays, whereas antimicrobial activity was assessed using the minimum inhibitory concentration (MIC) method. Subjection of the DCM extract to column chromatography resulted in the isolation of a compound elucidated as olean-12-en-28-butanol-1-one, 3-hydroxy-4,4,10, 14, 20-pentamethyl (D4). Both the DPPH, H2O2 radical scavenging activity and reducing power assays revealed a significant antioxidant potential of compound D4 with an IC50 of 0.701 mg/mL, lower than that of gallic acid (0.793 mg/mL) for the H2O2 radical scavenging assay. The results also indicated good antibacterial activity of D4 with an IC50 of 0.25 mg/mL, compared to ciprofloxacin with an IC50 of 0.0039 mg/mL, against two Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and three Gram-positive (Streptococcus pyogenes, Bacillus cereus and Staphylococcus aureus) bacteria. This study is the first to report on the isolation of the olean-12-en-28-butanol derivative from mistletoe of the South African ecotype.

Evaluation of Gram Stain-Guided Antibiotic Therapy for Methicillin-Resistant Staphylococcus aureus Pneumonia in Intensive Care Unit Patients.

Background: Despite high negative predictive values (NPVs) seen with methicillin-resistant Staphylococcus aureus (MRSA) nares polymerase chain reaction (PCR) assays, utilization of both respiratory sample Gram stain and MRSA nares PCR in patients with pneumonia may contribute to overuse of laboratory resources. The purpose of this study was to evaluate if a Gram stain demonstrating no Gram-positive organisms from a respiratory sample is sufficient to allow for de-escalation of vancomycin therapy. Methods: This single center study retrospectively identified intensive care unit (ICU) patients started on vancomycin for presumed pneumonia at University of Wisconsin (UW) Health in Madison, WI between August 2022 and March 2023. Patients with respiratory sample demonstrating no Gram-positives on Gram stain met inclusion criteria if the sample was ordered within 24 h of vancomycin initiation. The primary outcome was NPV of respiratory sample Gram stain demonstrating no Gram-positive organisms with respect to MRSA detection of the respiratory culture. Secondary outcomes included the NPV of combined MRSA nares PCR plus respiratory sample Gram stain, and difference in time to event in patients that had both a respiratory sample and MRSA nares PCR ordered. Results: A total of 370 patients were screened for study eligibility; of which 99 patients met inclusion criteria. NPV of respiratory sample Gram stain was 99% for MRSA culture. The combined NPV of respiratory sample Gram stain plus MRSA nares PCR was 98.9% for MRSA culture (n = 88). Respiratory sample was ordered 2.3 h faster compared to MRSA nares PCR (4.3 vs 6.6 h, P = .036). Respiratory sample Gram stain resulted 4.5 h faster compared to MRSA nares PCR (10.7 vs 15.2 h, P = .002). Conclusion: Respiratory sample Gram stains demonstrating no Gram-positive organisms may be used to de-escalate vancomycin and deprioritize the use of MRSA nares PCR.

Antimicrobial resistance in intensive care patients hospitalized with SEPSIS: a comparison between the COVID-19 pandemic and pre-pandemic era

IntroductionCoronavirus disease 2019 (COVID-19) is a highly contagious viral illness caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has had a dramatic effect on the world, resulting in millions of deaths worldwide and causing drastic changes in daily life. A study reported that septic complications were associated with high mortality in COVID-19 patients. This study aimed to evaluate how the COVID-19 pandemic changed the pre-pandemic and post-pandemic prevalence of sepsis in ICUs and to evaluate the different risk factors associated with mortality and the different diffusion of microorganisms and their resistance.Materials and methodsWe conducted a single-center retrospective observational clinical study, observing all patients in the ICU of the SS Annunziata Hospital in Chieti (Italy) who were diagnosed with sepsis and had a bacterial isolate from their blood culture. Sepsis was diagnosed by SEPSIIS III criteria. We enrolled all in-patients in the ICU from January 2018 to December 2021. We divided the patients into three groups: (1) non-pandemic period (Np) hospitalized in 2018–2019, (2) pandemic period (Pp)-COVID hospitalized in 2020–2021 with a diagnosis of COVID-19, and (3) Pp-non-COVID patients hospitalized in 2020–2021 without a diagnosis of COVID-19.ResultsFrom January 2018 to December 2021, 1,559 patients were admitted to the ICU, of which 211 patients [36 (17.1%) in 2018, 52 (24.6%) in 2019, 73 (34.6%) in 2020, and 50 (23.7%) in 2021, respectively] met the selection criteria: 88 patients in period Np, 67 patients in Pp without COVID-19, and 56 patients Pp with COVID-19. The overall mortality of these patients was high (65.9% at 30 days in Np), but decreased during the Pp (60.9%): Pp-non-COVID was 56.7% vs. Pp-COVID 66.1%, with a statistically significant association with APACHE III score (OR 1.08, 95%CI 1.04–1.12, p &amp;lt; 0.001), SOFA score (OR 1.12, 95%CI 1.03–1.22, p = 0.004), and age (OR 1.04, 95%CI 1.02–1.07, p &amp;lt; 0.0001). Between the Np vs. Pp periods, we observed an increase in a few Gram-positive bacteria such as S. capitis (1 pt. −0.9% vs. 14 pt. −7.65%- p = 0.008), S. epidermidis, Streptococcus spp., and E. faecalis, as well as a decrease in a case of blood culture positive for S. aureus, S. hominis, and E. faecium. In Gram-negative bacteria, we observed an increase in cases of Acinetobacter spp. (Np 6 pt. −5.1%- vs. Pp 20 pt. −10.9%, p = 0.082), and Serratia spp., while cases of sepsis decreased from E. faecium (Np 11 pt. −9.4%- vs. Pp 7 pt. −3.8%, p = 0.047), and Enterobacter spp., S. haemolyticus, S. maltophilia, Proteus spp., and P. aeruginosa have not changed. Finally, we found that resistance to OXA-48 (p = 0.040), ESBL (p = 0.002), carbapenems (p = 0.050), and colistin (p = 0.003) decreased with time from Np to Pp, particularly in Pp-COVID.ConclusionThis study demonstrated how the COVID-19 pandemic changed the prevalence of sepsis in the ICU. It emerged that the risk factors associated with mortality were APACHE and SOFA scores, age, and, above all, the presence of ESBL-producing bacteria. Despite this, during the pandemic phase, we have observed a significant reduction in the emergence of resistant germs compared to the pre-pandemic phase.

Immunogenicity and Protective Capacity of Sugar ABC Transporter Substrate-Binding Protein against Streptococcus suis Serotype 2, 7 and 9 Infection in Mice.

Background:Streptococcus suis (S. suis) is a Gram-positive bacterium that causes substantial disease in pigs. S. suis is also an emerging zoonoses in humans, primarily in Asia, through the consumption of undercooked pork and the handling of infected pig meat as well as carcasses. The complexity of S. suis epidemiology, characterized by the presence of multiple bacterial serotypes and strains with diverse sequence types, identifies a critical need for a universal vaccine with the ability to confer cross-protective immunity. Highly conserved immunogenic proteins are generally considered good candidate antigens for subunit universal vaccines. Methods: In this study, the cross-protection of the sugar ABC transporter substrate-binding protein (S-ABC), a surface-associated immunogenic protein of S. suis, was examined in mice for evaluation as a universal vaccine candidate. Results: S-ABC was shown to be highly conserved, with 97% amino acid sequence identity across 31 S. suis strains deposited in GenBank. Recombinantly expressed S-ABC (rS-ABC) was recognized via rabbit sera specific to S. suis serotype 2. The immunization of mice with rS-ABC induced antigen-specific antibody responses, as well as IFN-γ and IL-4, in multiple organs, including the lungs. rS-ABC immunization conferred high (87.5% and 100%) protection against challenges with S. suis serotypes 2 and 9, demonstrating high cross-protection against these serotypes. Protection, albeit lower (50%), was also observed in mice challenged with S. suis serotype 7. Conclusions: These data identify S-ABC as a promising antigenic target within a universal subunit vaccine against S. suis.

A new polyazomethine-based pyrazole moiety and its reinforced nanocomposites @ ZnO for antimicrobial applications

ABSTRACT A new class of biologically active polyazomethine/pyrazole and their related nanocomposites, polyazomethine/pyrazole/zinc oxide nanoparticles, have been successfully synthesized through the polycondensation technique in the form of polyazomethine pyrazole (PAZm/Py4–6) and polyazomethine/pyrazole/zinc oxide nanoparticles (PAZm/Py/ZnOa-c). The polymeric nanocomposites were prepared with a 5% loading of zinc oxide nanofiller using the same preparation technique, in addition to the help of ultrasonic radiation. The characteristics of the new polymers, such as solubility, viscometry, and molecular weight, were examined. All the polymers were completely soluble in the following solvents: concentrated sulfuric acid, formic acid, dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran. Furthermore, the weight loss of the polyazomethine pyrazole (4, 5, and 6) at 800 °C was 67%, 95%, and 86%, respectively, which indicates the thermal stability of these polymers. At 800 °C, the polyazomethine/pyrazole/zinc oxide nanoparticles (a, b, and c) lost 74%, 68%, and 75% of their weight, respectively. This shows that adding zinc oxide nanoparticles made these compounds more stable at high temperatures. The X-Ray diffraction pattern of the polyazomethine pyrazole (PAZm/Py4–6) shows a number of sharp peaks with varying intensities. The polymers that were studied had straight crystal structures. Furthermore, the measurements of polyazomethine/pyrazole/zinc oxide nanoparticles (PAZm/Py/ZnOa-c) indicate a good merging of zinc oxide nanoparticles into the matrix of polymers. The antimicrobial activity of polymers and polymer nanocomposites was tested against some selected bacteria and fungi. The synthesized polymer (c) shows the highest activity against the two types of gram-negative bacteria selected. Most tested compounds were found to be effective against gram-positive bacteria except polyazomethine pyrazole (PAZm/Py5) and polyazomethine pyrazole (PAZm/Py6), which do not exhibit any activity. The synthesized polymers and their related nanocomposites were tested for their ability to kill the chosen fungi. All of them were effective against Aspergillus flavus, but only polyazomethine pyrazole (PAZm/Py4) and polyazomethine/pyrazole/zinc oxide (PAZm/Py/ZnOc) were effective against Candida albicans.

Levels of IL-6 and IL-8 in Complicated versus Uncomplicated Urinary Tract Infection

Urinary tract infections (UTIs) are one of the world's most frequent infectious diseases, affecting 150 million people each year and resulting in severe morbidity and high medical expenditures. UTIs can be clinically defined as uncomplicated UTIs (uUTIs) or complicated UTIs (cUTIs) to differentiate infections of benign origin from those with a higher risk of recurrence or progression to severe pathology. The aim of this study was to evaluate interleukin-6 (IL-6) and IL-8 as potential biomarkers in differentiating complicated and uncomplicated. Ninety samples of urine were collected. There were 43 samples from healthy controls and 47 samples from UTI patients—those who have been clinically diagnosed with UTIs by the urologist. The serum IL-6 and IL-8 were measured using an enzyme-linked immunosorbent assay and commercially available kits. The levels of both IL-6 and IL-8 were significantly higher in UTI patient then in control subjects (p=0.001, p=0.001). A significant difference was observed in the mean of level IL-6 between culture positive UTI patients and culture negative UTI patients (p=0.014). In addition, the type of bacterial growth, a significant difference was observed in the mean of serum IL-6 and IL-8 level in UTI caused by gram negative bacteria in comparison with UTI caused by gram positive bacteria. High levels of IL-6 are associated with the growth of gram-negative bacteria, and this indicates that gram-negative bacteria could induce stronger inflammatory responses than gram-positive bacteria. IL-8 levels are higher in UTIs caused by gram-negative bacteria. This result further supported the evidence that gram-negative bacteria are potent inducers of inflammatory responses.

Gentamicin concentration and acute kidney injury in term neonates treated for neonatal sepsis with gentamicin and ampicillin-cloxacillin combination.

Gentamicin is widely used to treat neonatal infections caused by both Gram-negative and Gram-positive bacteria, and the WHO recommends its use while monitoring serum creatinine and gentamicin concentrations to avoid drug-induced nephrotoxicity and ototoxicity. Yet in some resource-limited settings, the drug is used without monitoring. A population pharmacokinetics study involving term neonates with neonatal infection admitted to a neonatal unit. Participants were started on intravenous gentamicin 5 mg/kg once a day in combination with ampicilin-cloxacillin. Blood samples for serum gentamicin concentration were taken at 0.25, 0.5, 1, 2, 3, 5, 6, 8, 10, 12, 14, 16, 18, 20, 23, and 24 hours after the initial dose, each participant contributing two samples to the 24 hour sampling schedule. An additional sample for trough concentration was taken from each participant just before the third gentamicin dose while serum creatinine concentration was measured before and after treatment. Twenty-four participants were enrolled into the study and included in the final analysis. Mean (SD) peak and trough serum gentamicin concentrations were 16.66 (0.64) µg/mL and 3.28 (0.70) µg/mL, respectively. Gentamicin clearance (CL) was 0.40 mL min-1 kg-1 and volume of distribution (VD) was 0.31 L kg-1. Mean (SD) serum creatinine level after treatment was 209.7 (70.4) µmol/L compared to 103.3 (23.6) µmol/L before treatment [mean difference (106.4 ± 67.1; 95% confidence interval (CI): 78.1; 134.7 µmol/L; t (23) = 7.77; P < 0.001]. All participants fulfilled the Kidney Disease Improving Global Outcomes (KDIGO) criteria for acute kidney injury after treatment. Treatment of neonatal infection with antimicrobial regimen containing gentamicin, without renal function and gentamicin concentration monitoring, carries a significant risk for drug-induced acute kidney injury.

Identification of ClpB, a molecular chaperone involved in the stress tolerance and virulence of Streptococcus agalactiae

Bacterial ClpB is an ATP-dependent disaggregate that belongs to the Hsp100/Clp family and facilitates bacterial survival under hostile environmental conditions. Streptococcus agalactiae, which is regarded as the major bacterial pathogen of farmed Nile tilapia (Oreochromis niloticus), is known to cause high mortality and large economic losses. Here, we report a ClpB homologue of S. agalactiae and explore its functionality. S. agalactiae with a clpB deletion mutant (∆clpB) exhibited defective tolerance against heat and acidic stress, without affecting growth or morphology under optimal conditions. Moreover, the ΔclpB mutant exhibited reduced intracellular survival in RAW264.7 cells, diminished adherence to the brain cells of tilapia, increased sensitivity to leukocytes from the head kidney of tilapia and whole blood killing, and reduced mortality and bacterial loads in a tilapia infection assay. Furthermore, the reduced virulence of the ∆clpB mutant was investigated by transcriptome analysis, which revealed that deletion of clpB altered the expression levels of multiple genes that contribute to the stress response as well as certain metabolic pathways. Collectively, our findings demonstrated that ClpB, a molecular chaperone, plays critical roles in heat and acid stress resistance and virulence in S. agalactiae. This finding provides an enhanced understanding of the functionality of this ClpB homologue in gram-positive bacteria and the survival strategy of S. agalactiae against immune clearance during infection.

Extraction of cellulose from halophytic plants for the synthesis of a novel biocomposite.

Cellulose nanofibers, a sustainable and promising material with widespread applications, exhibit appreciable strength and excellent mechanical and physicochemical properties. The preparation of cellulosic nanofibers from food or agricultural residue is not sustainable. Therefore, this study was designed to use three halophytic plants (Cressa cretica, Phragmites karka, and Suaeda fruticosa) to extract cellulose for the subsequent conversion to cellulosic nanofibers composites. The other extracted biomass components including lignin, hemicellulose, and pectin were also utilized to obtain industrially valuable enzymes. The maximum pectinase (31.56 IU mL-1), xylanase (35.21 IU mL-1), and laccase (15.89 IU mL-1) were produced after the fermentation of extracted pectin, hemicellulose, and lignin from S. fruticosa, P. karka, and C. cretica, respectively. Cellulose was methylated (with a degree of substitution of 2.4) and subsequently converted into a composite using polyvinyl alcohol. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed the successful synthesis of the composites. The composites made up of cellulose from C. cretica and S. fruticosa had a high tensile strength (21.5 and 15.2 MPa) and low biodegradability (47.58% and 44.56%, respectively) after dumping for 3 months in soil, as compared with the composite from P. karka (98.79% biodegradability and 4.9 MPa tensile strength). Moreover, all the composites exhibited antibacterial activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae) and gram-positive bacteria (Staphylococcus aureus). Hence, this study emphasizes the possibility for various industrial applications of biomass from halophytic plants.

Utilizing Rapid Hydrogen Peroxide Generation from 6-Hydroxycatechol to Design Moisture-Activated, Self-Disinfecting Coating.

A coating that can be activated by moisture found in respiratory droplets could be a convenient and effective way to control the spread of airborne pathogens and reduce fomite transmission. Here, the ability of a novel 6-hydroxycatechol-containing polymer to function as a self-disinfecting coating on the surface of polypropylene (PP) fabric was explored. Catechol is the main adhesive molecule found in mussel adhesive proteins. Molecular oxygen found in an aqueous solution can oxidize catechol and generate a known disinfectant, hydrogen peroxide (H2O2), as a byproduct. However, given the limited amount of moisture found in respiratory droplets, there is a need to enhance the rate of catechol autoxidation to generate antipathogenic levels of H2O2. 6-Hydroxycatechol contains an electron donating hydroxyl group on the 6-position of the benzene ring, which makes catechol more susceptible to autoxidation. 6-Hydroxycatechol-coated PP generated over 3000 μM of H2O2 within 1 h when hydrated with a small amount of aqueous solution (100 μL of PBS). The generated H2O2 was three orders of magnitude higher when compared to the amount generated by unmodified catechol. 6-Hydroxycatechol-containing coating demonstrated a more effective antimicrobial effect against both Gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria when compared to unmodified catechol. Similarly, the self-disinfecting coating reduced the infectivity of both bovine viral diarrhea virus and human coronavirus 229E by as much as a 2.5 log reduction value (a 99.7% reduction in viral load). Coatings containing unmodified catechol did not generate sufficient H2O2 to demonstrate significant virucidal effects. 6-Hydroxycatechol-containing coating can potentially function as a self-disinfecting coating that can be activated by the moisture present in respiratory droplets to generate H2O2 for disinfecting a broad range of pathogens.

Unmasking Bacterial Identities: Exploiting Silver Nanoparticle 'Masks' for Enhanced Raman Scattering in the Rapid Discrimination of Diverse Bacterial Species and Antibiotic-Resistant Strains.

Unraveling bacterial identity through Raman scattering techniques has been persistently challenging due to homogeneously amplified Raman signals across a wide variety of bacterial molecules, predominantly protein- or nucleic acid-mediated. In this study, we present an approach involving the use of silver nanoparticles to completely and uniformly "mask" adsorption on the surface of bacterial molecules through sodium borohydride and sodium chloride. This approach enables the acquisition of enhanced surface-enhanced Raman scattering (SERS) signals from all components on the bacterial surface, facilitating rapid, specific, and label-free bacterial identification. For the first time, we have characterized the identity of a bacterium, including its DNA, metabolites, and cell walls, enabling the accurate differentiation of various bacterial strains, even within the same species. In addition, we embarked on an exploration of the origin and variability patterns of the main characteristic peaks of Gram-positive and Gram-negative bacteria. Significantly, the SERS peak ratio was found to determine the inflection point of accelerated bacterial death upon treatment with antimicrobials. We further applied this platform to identify 15 unique clinical antibiotic-resistant bacterial strains, including five Escherichia coli strains in human urine, a first for Raman technology. This work has profound implications for prompt and accurate identification of bacteria, particularly antibiotic-resistant strains, thereby significantly enhancing clinical diagnostics and antimicrobial treatment strategies.

Ethynyl-substituted benzosiloxaboroles: the role of C(π)⋯B interactions in their crystal packing and use in Cu(i)-catalyzed 1,3-dipolar cycloaddition.

The synthesis and characterization of two novel 6-ethynyl-7-halogen substituted benzosiloxaboroles (Hal = F, Cl) is reported. The crystal structures of these compounds show a unique type of supramolecular assembly dictated by distinctive C(π)⋯B interactions resulting in the formation of columnar networks involving alternating ethynyl groups and boron atoms. The QTAIM, NBO and NCI analyses were performed in order to obtain a deeper quantitative insight into the nature of these interactions including energy and charge density distribution. The fluoro derivative 1c was used as a starting material in Cu-catalyzed 1,3-dipolar cycloaddition reactions with substituted benzenesulfonyl azides giving rise to benzosiloxaboroles with pendant 1-(arylsulfonyl)-1,2,3-triazole-4-yl functionalities or analogous ionic species, i.e., 1,2,3-triazolium arylsulfonates. Screening of antimicrobial activity of obtained derivatives against a wide selection of Gram-positive and Gram-negative bacteria as well as fungi strains was performed and the obtained results were compared with the data obtained previously for related benzosiloxaborole derivatives.

PHYTOCHEMICALS SCREENING, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITY OF CARICA PAPAYA LEAF EXTRACTS

Objective: The objective of the present study aimed at investigating the phytochemical antioxidant and anti-microbial properties of Carica papaya leaf extracts. Methods: As phytochemicals are biologically active compounds and a powerful group of plant chemicals believed to stimulate the immune system along with antioxidants, the molecules which hinder oxidation of other molecules by the process of inhibiting or by generating the oxidizing chain reactions and preventing diseases. The anti-microbial activity on various gram-positive and gram-negative bacteria were determined using zone of inhibition and antioxidant by the 2,2,1-diphenyl-1-picrylhydrazyl method. Results: Phytochemical screening, antioxidant and antibacterial potential were determined using different aqueous and organic solvents in addition to the determination of trace element in leaves of C. papaya. Antioxidant activity using DPPH free radical scavenging assay indicated leaves extracts leaves showed inhibition of per oxidation. The result showed that the ethanolic extract of C. papaya possessed a significant antioxidant activity as compared to methanol and aqueous extract. The antibacterial study showed leaves extract is the best to cope infectious action of bacteria. Conclusion: This study was conducted to test the medicinal profile of C. papaya by extracting secondary metabolites with organic and aqueous solvents. Ethanol was found to be the best solvents of choice to extract natural products to get maximum medicinal benefits and could be used to medicinal formulation against different infectious diseases.

Direct and Sunlight-Induced Photosensitizing Antibacterial Activities of Curcuma longa Extract

Curcuma longa is a widely used plant in folk medicine. Here, we assessed the antimicrobial activities of the ethanolic extract of Curcuma longa with particular emphasis on its combined effect with sunlight, as the extract can produce fluorescence in the presence of UV rays. Curcumin is one of the most active ingredients of Curcuma longa. The ethanolic extract of Curcuma longa when added to lawn cultures of gram-positive and gram-negative bacteria and exposed to sunlight the growth of bacteria was remarkably reduced. Micro broth dilution assay also showed decreased MIC values after exposure to sunlight with MSSA. Our results encourage the potential use of Curcuma longa as an antibacterial product.

Glycosyl transferase GT2 genes mediate the biosynthesis of an unusual (1,3;1,4)-β-glucan exopolysaccharide in the bacterium Sarcina ventriculi.

Linear, unbranched (1,3;1,4)-β-glucans (mixed-linkage glucans or MLGs) are commonly found in the cell walls of grasses, but have also been detected in basal land plants, algae, fungi and bacteria. Here we show that two family GT2 glycosyltransferases from the Gram-positive bacterium Sarcina ventriculi are capable of synthesizing MLGs. Immunotransmission electron microscopy demonstrates that MLG is secreted as an exopolysaccharide, where it may play a role in organizing individual cells into packets that are characteristic of Sarcina species. Heterologous expression of these two genes shows that they are capable of producing MLGs in planta, including an MLG that is chemically identical to the MLG secreted from S. ventriculi cells but which has regularly spaced (1,3)-β-linkages in a structure not reported previously for MLGs. The tandemly arranged, paralogous pair of genes are designated SvBmlgs1 and SvBmlgs2. The data indicate that MLG synthases have evolved different enzymic mechanisms for the incorporation of (1,3)-β- and (1,4)-β-glucosyl residues into a single polysaccharide chain. Amino acid variants associated with the evolutionary switch from (1,4)-β-glucan (cellulose) to MLG synthesis have been identified in the active site regions of the enzymes. The presence of MLG synthesis in bacteria could prove valuable for large-scale production of MLG for medical, food and beverage applications.