Bacterial Panel Research Articles

Bactericidal activities and biochemical features of 16 antimicrobial peptides against bovine-mastitis causative pathogens.

Mastitis, often caused by bacterial infection, is an inflammatory condition affecting the mammary glands. The condition is particularly prevalent in dairy cattle. Current treatment of bovine mastitis heavily relies on the use of antibiotics. To identify alternative solutions to antibiotic use, we evaluated the antimicrobial activity of 14 cathelicidins reported from 10 animal species. In conjunction, we assessed two bacteriocins against the bovine-mastitis causative bacterial panel, consisting of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Streptococcus agalactiae, Streptococcus dysgalactiae, and Streptococcus equi. Among the antimicrobial peptides (AMPs), cc-CATH3, ML-CATH, and PD-CATH proved to be highly active (minimum inhibitory concentration of 2-41μg/mL, 0.2-10.3μM) against all bacterial strains in the panel and field isolates from milk, with elevated somatic cell counts (≥ 500,000 cells/mL). Of the AMPs tested in this study, ML-CATH presented the highest level of effectiveness in controlling mastitis-associated bacterial strains while also possessing minimal cytotoxicity and functional stability against pH change and a high salt condition. The results of in silico analyses on the biochemical features of 12 helical cathelicidins revealed that the charge of AMPs appears to be a major determinant in killing Gram-negative bacteria. Furthermore, we observed a unique motif, "N(n≥3)-P(n≥1)-N(n≥3)", from the sequences of PMAP-36, cc-CATH3, ML-CATH, and PD-CATH that exhibits potent antimicrobial activity against a broad spectrum of bacteria compared to others. Our findings support the proposition that AMPs could serve as effective antimicrobial alternatives to conventional antibiotics in treating complex animal diseases caused by microbial infection, such as bovine mastitis.

Bushy-Tailed Multicationic Quaternary Phosphonium Compounds: Potent Amphiphilic Disinfectants with Promising Therapeutic Indices.

Quaternary ammonium compounds (QACs) have been essential for protecting human health for almost a century, functioning as surface disinfectants and sanitizers. With bacterial resistance increasing against commercially available QACs, the development of novel antimicrobials with divergent architectures is essential for effective infection prevention and control. Toward this end, our group has expanded beyond traditional ammonium scaffolds and explored the development of quaternary phosphonium compounds (QPCs). Herein, we report the synthesis and biological investigation of a series of 20 novel multicationic QPCs, bearing multiple short alkyl or aryl chains, also referred to as "bushy-tailed" multiQPCs; these structures were hypothesized to have strong bioactivity while displaying low mammalian toxicity. Select bushy-tailed QPC derivatives with trishexylphosphonium groups displayed single-digit or sub-micromolar activity against all seven bacteria tested, and MIC values of 2- to 8-fold better than their bushy-tailed QAC counterparts. Importantly, therapeutic indices of these bushy-tailed QPCs were favorable in many cases, and were ≥ 4 against the entire bacterial panel for pX-P6*,P6* and 1,8-P6*,P6*, superior to more traditional architectures. This work highlights the promise of a novel set of multicationic phosphonium compounds as novel disinfectants with potent bioactivities and low toxicity.

Synthesis and broad-spectrum biocidal effect of novel gemini quaternary ammonium compounds

Since the discovery of antimicrobial agents, the misuse of antibiotics has led to the emergence of bacterial strains resistant to both antibiotics and common disinfectants like quaternary ammonium compounds (QACs). A new class, ’gemini’ QACs, which contain two polar heads, has shown promise. Octenidine (OCT), a representative of this group, is effective against resistant microorganisms but has limitations such as low solubility and high cytotoxicity. In this study, we developed 16 novel OCT derivatives. These compounds were subjected to in silico screening to predict their membrane permeation. Testing against nosocomial bacterial strains (G+ and G-) and their biofilms revealed that most compounds were highly effective against G+ bacteria, while compounds 7, 8, and 10–12 were effective against G- bacteria. Notably, compounds 6–8 were significantly more effective than OCT and BAC standards across the bacterial panel. Compound 12 stood out due to its low cytotoxicity and broad-spectrum antimicrobial activity, comparable to OCT. It also demonstrated impressive antifungal activity. Compound 1 was highly selective to fungi and four times more effective than OCT without its cytotoxicity. Several compounds, including 4, 6, 8, 9, 10, and 12, showed strong virucidal activity against murine cytomegalovirus and herpes simplex virus 1. In conclusion, these gemini QACs, especially compound 12, offer a promising alternative to current disinfectants, addressing emerging resistances with their enhanced antimicrobial, antifungal, and virucidal properties.

Non-invasive early detection on esophageal squamous cell carcinoma and precancerous lesions by microbial biomarkers combining epidemiological factors in China.

Microbiota may be associated with esophageal squamous cell carcinoma (ESCC) development. However, it is not known the predictive value of microbial biomarkers combining epidemiological factors for the early detection of ESCC and precancerous lesions. A total of 449 specimens (esophageal swabs and saliva) were collected from 349 participants with different esophageal statuses in China to explore and validate ESCC-associated microbial biomarkers from genes level to species level by 16S rRNA sequencing, metagenomic sequencing and real-time quantitative polymerase chain reaction. A bacterial biomarker panel including Actinomyces graevenitzii (A.g_1, A.g_2, A.g_3, A.g_4), Fusobacteria nucleatum (F.n_1, F.n_2, F.n_3), Haemophilus haemolyticus (H.h_1), Porphyromonas gingivalis (P.g_1, P.g_2, P.g_3) and Streptococcus australis (S.a_1) was explored by metagenomic sequencing to early detect the participants in Need group (low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia and ESCC) vs participants without these lesions as the Noneed group. Significant quantitative differences existed for each microbial target in which the detection efficiency rate was higher in saliva than esophageal swab. In saliva, the area under the curve (AUC) based on the microbial biomarkers (A.g_4 ∩ P.g_3 ∩ H.h_1 ∩ S.a_1 ∩ F.n_2) was 0.722 (95% CI 0.621-0.823) in the exploration cohort. Combining epidemiological factors (age, smoking, drinking, intake of high-temperature food and toothache), the AUC improved to 0.869 (95% CI 0.802-0.937) in the exploration cohort, which was validated with AUC of 0.757 (95% CI 0.663-0.852) in the validation cohort. It is feasible to combine microbial biomarkers in saliva and epidemiological factors to early detect ESCC and precancerous lesions in China.

Whole-cell bacterial biosensor applied to identify the presence of Thaumatotibia leucotreta larva in citrus fruits by volatile sensing

The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick), is a major pest of citrus fruits and other plants and is defined as a quarantine pest in several countries. Supervision and visual monitoring are crucial for the detection of eggs and larvae. There is a growing need to implement alternative pest control strategies and early detection methodologies in the packing house before shipping. Biosensors may provide a better-suited solution, as they are portable, do not require expensive equipment, and may be used with simple methodologies. In this study, a whole-cell bacterial biosensor was developed to identify the presence of Thaumatotibia leucotreta larvae in citrus fruits. The volatile organic compounds (VOCs) released by the larvae were identified (n = 11), which were not previously tested. The change in the VOCs composition in infected and uninfected mandarin (Citrus reticulata) was examined using gas chromatography-mass spectrometry (GC-MS) and the bioluminescent bacterial panel. During this work, two fixation methods (alginate beads and tablets) were tested for the bioluminescent bacteria cells, and tablets were preferred due to their higher uniformity and consistency of the light signal from the cells. Furthermore, the response of the bacteria to the changes in the concentration of VOCs as a result of a change in the amount of the larvae was examined (larvae n = 3, 6, or 9). In addition, in order to demonstrate the ability of the whole-cell biosensor to detect the presence of larva within the fruit, infected and uninfected mandarins were tested on the 14th day of larval hatching. The results showed that the bioluminescent bacteria could differentiate between mandarins with and without larva. The differences in the light signals (Induction Factor (IF)) between the mandarin fruits can be seen in the results with the larva (cytotoxicity IF = 3.046, genotoxicity IF = 2.643, and quorum sensing IF = 1.954) and without (cytotoxicity IF = 1.589, genotoxicity IF = 1.149 and quorum sensing IF = 1.205). The findings of this study make it possible to further develop a prototype using bioluminescent bacteria in order to detect pests of citrus fruits. The early detection of infected fruits will allow their filtering from the crop and therefore reduce the damage to additional fruits. Even one larva can invalidate the whole stock and the plot for future export.

Clinical performance evaluation of TAQPATH Enteric Bacterial Select Panel for the detection of common enteric bacterial pathogens in comparison to routine stool culture and other qPCR-based diagnostic tests.

Enteric bacterial infections caused by Salmonella, Shigella, pathogenic Escherichia coli, and Campylobacter represent one of the most common causes of infectious enteritis worldwide. The timely and accurate diagnosis of pathogens causing gastroenteritis is crucial for patient care, public health, and disease surveillance. While stool culture has long been the standard and highly specific method for detecting enteric pathogens, it is labor-intensive and time-consuming with limited sensitivity. To improve patient outcomes, there is a need to implement new cost-effective approaches for the detection of bacterial enteric pathogens with higher sensitivity and faster time to result. This study shows that multiplex real-time polymerase chain reaction-based tests, such as the TAQPATH Enteric Bacterial Select Panel, are accurate and cost-effective diagnostic alternatives for the detection and differentiation of the most common enteric bacterial pathogens, offering quicker time to result and higher sensitivity compared to routine stool culture.

Synthesis and biological evaluation of new naphthalimide–thiourea derivatives as potent antimicrobial agents active against multidrug-resistant Staphylococcus aureus and Mycobacterium tuberculosis

Novel series of naphthalimide thiourea derivatives were synthesised and evaluated against bacterial pathogen panel and mycobacterial pathogen panel.

A diagnostic stewardship approach to prevent unnecessary testing of an enteric bacterial molecular panel.

After stool culture was replaced by an enteric bacterial panel (EBP) at the Johns Hopkins Hospital (JHH), many EBPs were ordered >3 days after admission (EBP >3 days) with low yield. To reduce unnecessary testing, a hard stop for ordering EBP >3 days was established with the option to override the restriction. The present study retrospectively evaluates the usefulness of overriding that restriction. A retrospective chart review was performed on all patients with an EBP >3 days at the JHH from November 2021 to October 2022. The override provided only one new diagnosis of Salmonella infection in a patient who developed diarrhea within 3 days of admission but was not tested by EBP until day 5. There were no positive EBPs >3 days in patients without diarrhea or who developed diarrhea >3 days after admission (diarrhea >3 days). Most patients with requests to override the restriction were also tested for Clostridioides difficile. All patients positive for C. difficile received treatment and their C. difficile positive test resulted >1 day before the EBP was run. There were no differences in yield in patients >65 years of age with significant comorbidities or associated with neutropenia, leukocytosis, human immunodeficiency virus status, or lactoferrin positivity. There were no positive tests in patients receiving stool softeners within the previous 48 hours of testing. Overriding the hard stop should not be approved in patients without diarrhea or with diarrhea >3 days, who received stool softeners within the previous 48 hours or have not been tested for more common causes of hospital-acquired diarrhea.IMPORTANCETesting for enteric bacterial pathogens in patients hospitalized for more than 3 days is almost always inappropriate. Our study validates the utility of the 3-day rule and the use of clinical decision support tools to decrease unnecessary testing of enteropathogenic bacteria other than C. difficile. Overriding the restriction was very low yield. Our study highlights the importance of diagnostic stewardship and further refines the criteria for allowing providers to override the restriction while monitoring the impact of the interventions.

Potent antibacterial activity in surgical wounds with local administration of D-PLEX100

Despite significant advances in infection control guidelines and practices, surgical site infections remain a substantial cause of morbidity, prolonged hospitalization, and mortality. The most effective component of SSI reduction strategies is the preoperative administration of intravenous antibiotics; however, systemic antibiotics drug exposure diminishes rapidly and may result in insufficient prophylactic activity against susceptible and resistant SSI pathogens at the wound. D-PLEX100 (D-PLEX) is an antibiotic-releasing drug (doxycycline) that is supplied as a sterile powder for paste reconstitution with sterile saline. D-PLEX paste is administered locally into the incision site along the entire length of soft tissue and sternal bone wound surfaces prior to skin closure. A single D-PLEX administration is intended for 30 days of constant antimicrobial prophylaxis in the prevention of incisional SSIs. We evaluated D-PLEX minimal bactericidal concentration (MBC) against a panel of bacteria that is prevalent in the abdominal wall and sternal surgical procedures including doxycycline susceptible and resistant strains. D-PLEX in vivo efficacy was assessed in incisional infection rabbit models (abdominal wall and sternal) challenged with a similar bacterial panel. The D-PLEX drug exposure profile was determined by in vitro release assay, and in vivo by quantitative pharmacokinetic parameters of local and systemic doxycycline concentrations released from D-PLEX after local administration in incisional rabbit models. Analyses of pathogens and variations in antibiotic resistance from wound isolates were determined from patients who participated in a previously reported prospective randomized trial that assessed the SSI rate in D-PLEX plus standard of care (SOC) versus SOC alone in colorectal resection surgery. The D-PLEX MBC values demonstrated >3- Log10 reduction in all the organisms tested relative to untreated controls, including doxycycline-resistant bacteria (i.e., Methicillin-resistant Staphylococcus aureus (MRSA), K. pneumoniae, and P. aeruginosa). In vivo, D-PLEX significantly reduced the bacterial loads in all the bacteria tested in both animal models (p=0.0001) with a marked impact observed in E. Coli (>6.5 Log10 reduction). D-PLEX exhibited a zero-order release kinetics profile in vitro for 30 days (R2 = 0.971) and the matched in vivo release profile indicated a constant local release of protein-unbound doxycycline for 30 days at 3-5 mcg/mL with significantly lower (>3 orders of magnitudes) systemic levels. In colorectal surgery patients, where significant SSI reduction was observed, analysis of the positive cultures in the overall population indicated similar pathogen diversity and antibiotic resistance rates in both treatment arms. However, almost all the patients with positive culture in the SOC arm were adjudicated as SSI (94%) compared to only 28% in the D-PLEX arm. The SSI-adjudicated D-PLEX patients also exhibited lower resistance rates to the SOC antibiotics and to MDRs compared to patients in the SOC arm. Thus, D-PLEX provides safe and effective prophylaxis activity against the most prevalent SSI pathogens including doxycycline-susceptible and resistant bacteria. Our findings suggest that D-PLEX is a promising addition to SSI prophylactic bundles and may address the gaps in current SSI prophylaxis. D-PLEX is now evaluated in Phase 3 clinical trial.

Real-life impact of respiratory panel PCR assay on antibiotic prescription in geriatric acute care in the pre-COVID-19 era

ObjectivesIn this era of bacterial resistance, avoiding inappropriate use of antibiotic treatments is of major importance. Respiratory tract infections are frequent among older patients, and differentiating viral from bacterial infections is a challenge. The aim of our study was to evaluate the impact of recently available respiratory PCR testing on antimicrobial prescription in geriatric acute care. MethodsWe performed a retrospective study, including all hospitalized geriatric patients who had had multiplex respiratory PCR testing prescribed from 1st October 2018 to 30th September 2019. The PCR test comprised a respiratory viral panel (RVP) and a respiratory bacterial panel (RBP). PCR testing could be prescribed at any time during hospitalization by geriatricians. Our primary endpoint was antibiotic prescription after viral multiplex PCR testing results. ResultsAll in all, 193 patients were included, 88 (45.6%) of whom had positive RVP, while none had positive RBP. Patients with positive RVP had significantly fewer antibiotic prescriptions following test results than patients with negative RVP (odds ratio (OR) 0.41, 95% confidence interval (CI) 0.22–0.77; p = 0.004). Among positive-RVP patients, factors associated with antibiotic continuation were presence of radiological infiltrate (OR 12.02, 95%CI 3.07–30.29), and detected Respiratory Syncytial Virus (OR 7.54, 95%CI 1.74–32.65). That said, discontinuation of antibiotic treatment seems safe. ConclusionIn this population, the impact of viral detection by respiratory multiplex PCR on antibiotic therapy was low. It could be optimized by means of clearly formulated local guidelines, qualified staff and specific training by infectious disease specialists. Cost-effectiveness studies are necessary.

Delayed Onset ICANS Leading to Bilateral Cranial Neuropathies: Two Case Reports (P12-13.005)

<h3>Objective:</h3> To describe two cases of bilateral facial nerve neuropathy from late onset immune effector cell-associated neurotoxicity syndrome (ICANS) after chimeric antigen receptor T-cell (CAR-T) therapy for treatment of Multiple Myeloma. <h3>Background:</h3> ICANS is a complication of CAR-T therapy which typically occurs within the first week of treatment. Manifestations can include encephalopathy with confusion and behavioral changes, headache, agraphia, tremors, seizures, cerebral edema, or death. Isolated cranial neuropathies, particularly after this period, have not been reported. <h3>Design/Methods:</h3> Case report. <h3>Results:</h3> Two patients, a 69-year-old male (case 1) and a 67-year-old female (case 2), presented with facial nerve palsy 3 weeks (20 and 21 days respectively) after CAR-T therapy for multiple myeloma. Neither of the patients had developed symptoms of neurotoxicity immediately after CAR-T treatment. Case 1 experienced gradual onset of decreased taste, facial numbness, inability to smile or move his eyebrows, and drooling. Exam showed bilateral facial weakness in a lower motor neuron pattern, worse on the left as compared to the right. Case 2 experienced right-sided facial droop with inability to move her right eyebrow or symmetrically smile, right ear fullness, and right-sided drooling. Exam revealed right-sided facial weakness in a lower motor neuron pattern. MRI of the brain in both patients demonstrated bilateral contrast enhancement of the facial nerves. Cerebrospinal fluid analysis in case 1 showed mildly elevated protein (67 mg/dL), with negative infectious studies, and no evidence of malignancy. Case 2 did not have lumbar puncture, but respiratory viral and bacterial pathogen panel was negative. Both patients were treated with a short course of oral dexamethasone with complete resolution in case 1, and partial improvement of symptoms in case 2. <h3>Conclusions:</h3> Delayed ICANS should be considered in CAR-T patients presenting with isolated cranial neuropathies after ruling out infection and malignancy. Treatment with steroids can lead to recovery. <b>Disclosure:</b> Miss Beck has nothing to disclose. Dr. Hasan has nothing to disclose. Dr. Mehta has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Adamas Pharma. Dr. Mehta has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Abbott. Dr. Mehta has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for CNS Ratings. Dr. Valencia Sanchez has nothing to disclose.

Synthesis and Bio‐evaluation of GR135486X Derivatives as Potent Anti‐Tubercular Agents

AbstractThe anilinopyridine derivatives were designed, synthesized and evaluated against Mycobacterium tuberculosis H37Rv. The detail SAR study was carried out using various analogues including positional isomers. The screening data revealed that the free −NH2 on pyridine ring is crucial for antitubercular activity. The current study identified three promising leads 16 e, 16 i and 16 o with MIC 3.1, 3.1 and 1.2 μM, respectively. Important to note that the compound 16 o showed excellent selectivity index of 135.58 when its antitubercular activity was compared with the inhibition of CHO−K1 cells. The other notable compounds were 16 b, 16 d, 16 e, 16 f, 16 g, 16 h, 16 i, 16 l and 16 q which exhibited anti‐TB activity with MIC ≤25 μM. Interestingly, compounds 16 e, 16 i and 16 o did not show inhibition of bacterial pathogen panel indicating the selectivity of this class of compounds towards Mtb. Furthermore, physico‐chemical and ADMET properties of the synthesized derivatives were studied. The compounds fulfill the criteria of Lipinski's rule of five for drug‐likeness.

Biocompatibility characterization of vaterite with a bacterial whole-cell biosensor

The growing biomedical challenges impose the continuous development of novel platforms. Ensuring the biocompatibility of drug delivery and implantable biomedical devices is an essential requirement. Calcium carbonate (CaCO3) in the form of vaterite nanoparticles is a promising platform, which has demonstrated distinctive optical and biochemical properties, including high porosity and metastability. In this study, the biocompatibility of differently shaped CaCO3 vaterite particles (toroids, ellipsoids, and spheroids) are evaluated by bacterial toxicity mode-of-action with a whole-cell biosensor. Different Escherichia coli (E. coli) strains were used in the bioluminescent assay, including cytotoxicity, genotoxicity and quorum-sensing. Firstly, both scanning electron microscopy (SEM) and fluorescence microscopy characterizations were conducted. Bacterial cell death and aggregates were observed only in the highest tested concentration of the vaterite particles, especially in toroids 15–25 µm. After, the bioluminescent bacterial panel was exposed to the vaterite particles, and their bioluminescent signal reflected their toxicity mode-of-action. The vaterite particles resulted in an induction factor (IF > 1) on the bacterial panel, which was higher after exposure to the toroids (1.557 ≤ IF ≤ 2.271) and ellipsoids particles (1.712 ≤ IF ≤ 2.018), as compared to the spheroids particles (1.134 ≤ IF ≤ 1.494), in all the tested bacterial strains. Furthermore, the vaterite particles did not affect the viability of the bacterial cells. The bacterial monitoring demonstrated the biofriendly nature of especially spheroids vaterite nanoparticles.

Evaluation of Viral and Bacterial Pathogens in the Central Nervous System Infections with Multiplex PCR.

To evaluate the bacterial and viral causes of central nervous system (CNS) infection by multiplex PCR. Descriptive study. Department of Medical Microbiology, Pamukkale University Faculty of Medicine, Turkey, from March 2016 to December 2021. Cerebrospinal fluid (CSF) samples of patients prediagnosed with CNS infection were included in the study. Viral pathogens were detected with the Multiplex real-time PCR panel (FTD Neuro9, Fast Track Diagnostics, Luxembourg) and bacterial pathogens with the multiplex real-time PCR panel (FTD Bacterial Meningitis, Fast Track Diagnostics, Luxembourg). The identification of bacteria growing in samples was done by conventional methods and with the Phoenix™ (Becton Dickinson Diagnostics, USA) automated system. CSF samples of 440 patients were evaluated using multiplex PCR panel. The viral factors included adenovirus (14.2%), human herpes virus 7 (1.5%), varicella zoster virus (1.3%), herpes simplex virus 1 (1.3%), cytomegalovirus (1.3%), Epstein-Barr virus (0.8%), human herpes virus (0.8%), herpes simplex virus 2 (0.3%), varicella zoster virus (0.3%), and parvovirus B19 (0.3%); and bacterial factors included Streptococcus pneumoniae (7.0%) and Neisseria meningitidis (0.9%). The bacterial growth was detected in the CSF culture was 4.9%. Among the growing bacteria, there were six different types that were not found on the multiplex PCR panel. The use of a comprehensive bacterial multiplex PCR panel containing common pathogens will be more effective in pathogen detection. Care should be taken, especially when interpreting the viral Multiplex PCR. Viral multiplex PCR, Bacterial multiplex PCR, Bacteria culture.

Gut and Gill-Associated Microbiota of the Flatfish European Plaice (Pleuronectes platessa): Diversity, Metabolome and Bioactivity against Human and Aquaculture Pathogens.

Similar to other marine holobionts, fish are colonized by complex microbial communities that promote their health and growth. Fish-associated microbiota is emerging as a promising source of bioactive metabolites. Pleuronectes platessa (European plaice, plaice), a flatfish with commercial importance, is common in the Baltic Sea. Here we used a culture-dependent survey followed by molecular identification to identify microbiota associated with the gills and the gastrointestinal tract (GIT) of P. platessa, then profiled their antimicrobial activity and metabolome. Altogether, 66 strains (59 bacteria and 7 fungi) were isolated, with Proteobacteria being the most abundant phylum. Gill-associated microbiota accounted for higher number of isolates and was dominated by the Proteobacteria (family Moraxellaceae) and Actinobacteria (family Nocardiaceae), whereas Gram-negative bacterial families Vibrionaceae and Shewanellaceae represented the largest group associated with the GIT. The EtOAc extracts of the solid and liquid media cultures of 21 bacteria and 2 fungi representing the diversity of cultivable plaice-associated microbiota was profiled for their antimicrobial activity against three fish pathogens, human bacterial pathogen panel (ESKAPE) and two human fungal pathogens. More than half of all tested microorganisms, particularly those originating from the GIT epithelium, exhibited antagonistic effect against fish pathogens (Lactococcus garvieae, Vibrio ichthyoenteri) and/or human pathogens (Enterococcus faecium, methicillin-resistant Staphylococcus aureus). Proteobacteria represented the most active isolates. Notably, the solid media extracts displayed higher activity against fish pathogens, while liquid culture extracts were more active against human pathogens. Untargeted metabolomics approach using feature-based molecular networking showed the high chemical diversity of the liquid extracts that contained undescribed clusters. This study highlights plaice-associated microbiota as a potential source of antimicrobials for the control of human and the aquaculture-associated infections. This is the first study reporting diversity, bioactivity and chemical profile of culture-dependent microbiota of plaice.

Metagenomic Insights into the Gut Microbiota of Eudrilus eugeniae (Kinberg) and Its Potential Roles in Agroecosystem.

Gut microbiomes, a consortium of microorganisms that live in the animal gut, are highly engineered microbial communities. It makes a major contribution to digestive health, metabolism management, and the development of a strong immune system in the host. The present study was taken up to answer the long-running question about the existence of truly indigenous microflora of the epigeic earthworm gut. This is due to the general difficulties of culturing many of the microorganisms found in soil or earthworms' gut. Keeping this fact in a view, the metagenomics approach using 16S rRNA marker gene incorporated with amplicon-based sequencing was used to explore microbiota of commercially overriding, diversely fed epigeic earthworm Eudrilus eugeniae (Kinberg) in three varied habitats viz., artificial soil (AS), organic agricultural farm soil (OAFS) and conventional agriculture farm soil (CAFS). There are predominant bacteria that belong to different phyla such as Proteobacteria (29.72-76.81%), Actinobacteria (11.06-34.42%), Firmicutes (6.02-19.81%), and Bacteroidetes (2.40-9.22%) present in the gut of E. eugeniae. The alpha diversity (Observed species, Chao1, ACE, Shannon, Simpson, and Fisher alpha) indices showed that OAFS had significantly higher alpha diversity than AS and CAFS groups. The core microbiota analysis showed that OAFS and AS groups had a relatively similar bacterial panel in comparison to the CAFS group. Various statistical tools i.e. MetagenomeSeq, LEfSe, and Random Forest analysis were performed and the findings demonstrated prevalence of the most significant bacterial genera; Aeromonas, Gaiella, and Burkholderia in CAFS group. Nonetheless, in AS and OAFS groups, the common existence of Anaerosporobacter and Aquihabitans were found respectively. Metagenomic functional prediction revealed that earthworms' gut microbial communities were actively involved in multiple organic and xenobiotics compound degradation-related pathways. This is the first research to use high-throughput 16S rRNA gene amplicon sequencing to show the gut microbiota of E. eugeniae in diverse agricultural systems. The findings suggest the configuration of the gut microbiota of earthworms and its potential role in the soil ecosystem depends on the microbial communities of the soil.

Whole-cell bacterial biosensor with the capability to detect red palm weevil, Rhynchophorus ferrugineus, in date palm trees, Phoenix dactylifera: a proof of concept study

The red palm weevil (RPW), Rhynchophorus ferrugineus, is considered a severe pest of palms. Usually, the early stages of infection are without visible signs. An attractive early sensing approach of non-visible infections is based on volatile organic compounds (VOCs). In this study, a whole-cell bacterial biosensor was used for the identification of RPW in date palm (Phoenix dactylifera). The cells are genetically modified to produce light in the presence of general stresses. The bioluminescent bacterial panel is based on three genetically engineered Escherichia coli strains that are sensitive to cytotoxicity (TV1061), genotoxicity (DPD2794), or quorum-sensing (K802NR). The bioluminescent bacterial panel detects the presence of VOCs and a change in the light signal is then generated, reflecting the health status of the date palm tree. The bioreporter bacteria cells are immobilized in calcium alginate tablets and placed in a sealed jar without direct contact with the tested sample, thereby exposing them only to the VOCs in the surrounding air. The immobilized bacteria cells were exposed to the air near infected by RPW or uninfected sugar canes, date palm tree pieces, and on date palm trees. Commercial plate reader was used for signal measurement. The findings show that quorum-sensing was induced by all the tested samples of infected sugar canes, date palm tree pieces, and date palm trees. While, cytotoxicity was induced only by infected date palm tree pieces, and genotoxicity was induced only by infected date palm trees. The bacterial monitoring results enable the identification of specific signatures that will allow a quick and accurate diagnosis.

Green synthesis and antibacterial evaluation of spiro fused tryptanthrin-thiopyrano[2,3-b]indole hybrids targeting drug-resistant S. aureus

Green and facile synthesis of 24 tryptanthrin-thiopyrano[2,3-b]indole hybrid molecules is described (i) by a thermal one-pot multi-component strategy, (ii) using ammonium acetate in solvent-free conditions at 100 °C and (iii) by electrochemical method at room temperature. The in vitro antibacterial activities of compounds were evaluated against bacterial pathogen panel including clinically relevant highly drug-resistant MRSA/VRSA isolates, which led to the identification of nitro-substituted hybrid molecule 4c as being the most potent molecule against S. aureus ATCC 29213 with a high selectivity index. Upon further analysis, 4c exhibited concentration dependent bactericidal activity with a long PAE (post-antibiotic effect) and synergized with linezolid against S. aureus. From the in vitro metabolic stability assay (using rat liver microsomes) it was found that 4c has half-life of >120 min. The co-crystallographic studies indicated that amino group in compound 4c is the potential binding site. From all the studies, it was clear that compound 4c exhibits all the hallmarks for positioning it as a novel anti-staphylococcal therapeutic option.

Exploration of Isoxazole-Carboxylic Acid Methyl Ester Based 2-Substituted Quinoline Derivatives as Promising Antitubercular Agents.

In pursuit of potent anti-TB agents active against drug resistant tuberculosis (DR-TB), herein we report synthesis and bio-evaluation of a new series of isoxazole-carboxylic acid methyl ester based 2-substituted quinoline derivatives. Preliminary evaluation indicated selectivity towards Mtb H37Rv, with no inhibition of non-tubercular mycobacterial (NTM) & bacterial pathogen panel. Out of 36 synthesized compounds, majority exhibited substantial inhibition of Mtb H37Rv (MIC 0.5-8 μg/mL). Cell viability test against Vero cells revealed no significant cytotoxicity. Further, screening against drug resistant strains (DR-Mtb) found hit compound displaying promising potency (MIC 1-4 μg/mL). Structure optimization of the hit led to the identification of lead compound demonstrating potent inhibition of both drug-susceptible Mtb (MIC 0.12 μg/mL) and drug-resistant Mtb (MIC 0.25-0.5 μg/mL) along with a high selectivity index (SI) >80. Taken together, with appreciable selectivity and potent activity, these chemotypes show prospect to be turned into a potential anti-TB candidate.

Whole-cell bacterial biosensor for volatile detection from Pectobacterium-infected potatoes enables early identification of potato tuber soft rot disease

Half of the harvested food is lost due to rots caused by microorganisms. Plants emit various volatile organic compounds (VOCs) into their surrounding environment, and the VOC profiles of healthy crops are altered upon infection. In this study, a whole-cell bacterial biosensor was used for the early identification of potato tuber soft rot disease caused by the pectinolytic bacteria Pectobacterium in potato tubers. The detection is based on monitoring the luminescent responses of the bacteria panel to changes in the VOC profile following inoculation. First, gas chromatography-mass spectrometry (GC-MS) was used to specify the differences between the VOC patterns of the inoculated and non-inoculated potato tubers during early infection. Five VOCs were identified, 1-octanol, phenylethyl alcohol, 2-ethyl hexanol, nonanal, and 1-octen-3-ol. Then, the infection was detected by the bioreporter bacterial panel, firstly measured in a 96-well plate in solution, and then also tested in potato plugs and validated in whole tubers. Examination of the bacterial panel responses showed an extensive cytotoxic effect over the testing period, as seen by the elevated induction factor (IF) values in the bacterial strain TV1061 after exposure to both potato plugs and whole tubers. Moreover, quorum sensing influences were also observed by the elevated IF values in the bacterial strain K802NR. The developed whole-cell biosensor system based on bacterial detection will allow more efficient crop management during postharvest, storage, and transport of crops, to reduce food losses.