The multifaceted roles of antibiotics and antibiotic resistance in nature

Unveiling Trends: Nanoscale Materials Shaping Emerging Biomedical Applications

The realm of biomedical materials continues to evolve rapidly, driven by innovative research across interdisciplinary domains. Leveraging big data from the CAS Content Collection, this study employs quantitative analysis through natural language processing (NLP) to identify six emerging areas within nanoscale materials for biomedical applications. These areas encompass self-healing, bioelectronic, programmable, lipid-based, protein-based, and antibacterial materials. Our Nano Focus delves into the multifaceted utilization of nanoscale materials in these domains, spanning from augmenting physical and electronic properties for interfacing with human tissue to facilitating intricate functionalities like programmable drug delivery.

Manuka honey as a non-antibiotic alternative against Staphylococcus spp. and their small colony variant (SCVs) phenotypes

The antibiotic resistance (ABR) crisis is an urgent global health priority. Staphylococci are among the problematic bacteria contributing to this emergency owing to their recalcitrance to many clinically important antibiotics. Staphylococcal pathogenesis is further complicated by the presence of small colony variants (SCVs), a bacterial subpopulation displaying atypical characteristics including retarded growth, prolific biofilm formation, heightened antibiotic tolerance, and enhanced intracellular persistence. These capabilities severely impede current chemotherapeutics, resulting in chronic infections, poor patient outcomes, and significant economic burden. Tackling ABR requires alternative measures beyond the conventional options that have dominated treatment regimens over the past 8 decades. Non-antibiotic therapies are gaining interest in this arena, including the use of honey, which despite having ancient therapeutic roots has now been reimagined as an alternative treatment beyond just traditional topical use, to include the treatment of an array of difficult-to-treat staphylococcal infections. This literature review focused on Manuka honey (MH) and its efficacy as an anti-staphylococcal treatment. We summarized the studies that have used this product and the technologies employed to study the antibacterial mechanisms that render MH a suitable agent for the management of problematic staphylococcal infections, including those involving staphylococcal SCVs. We also discussed the status of staphylococcal resistance development to MH and other factors that may impact its efficacy as an alternative therapy to help combat ABR.

Relevance of the Adjuvant Effect between Cellular Homeostasis and Resistance to Antibiotics in Gram-Negative Bacteria with Pathogenic Capacity: A Study of Klebsiella pneumoniae

Antibiotic resistance has become a global issue. The most significant risk is the acquisition of these mechanisms by pathogenic bacteria, which can have a severe clinical impact and pose a public health risk. This problem assumes that bacterial fitness is a constant phenomenon and should be approached from an evolutionary perspective to develop the most appropriate and effective strategies to contain the emergence of strains with pathogenic potential. Resistance mechanisms can be understood as adaptive processes to stressful conditions. This review examines the relevance of homeostatic regulatory mechanisms in antimicrobial resistance mechanisms. We focus on the interactions in the cellular physiology of pathogenic bacteria, particularly Gram-negative bacteria, and specifically Klebsiella pneumoniae. From a clinical research perspective, understanding these interactions is crucial for comprehensively understanding the phenomenon of resistance and developing more effective drugs and treatments to limit or attenuate bacterial sepsis, since the most conserved adjuvant phenomena in bacterial physiology has turned out to be more optimized and, therefore, more susceptible to alterations due to pharmacological action.

Navigating Antibacterial Frontiers: A Panoramic Exploration of Antibacterial Landscapes, Resistance Mechanisms, and Emerging Therapeutic Strategies

The development of effective antibacterial solutions has become paramount in maintaining global health in this era of increasing bacterial threats and rampant antibiotic resistance. Traditional antibiotics have played a significant role in combating bacterial infections throughout history. However, the emergence of novel resistant strains necessitates constant innovation in antibacterial research. We have analyzed the data on antibacterials from the CAS Content Collection, the largest human-curated collection of published scientific knowledge, which has proven valuable for quantitative analysis of global scientific knowledge. Our analysis focuses on mining the CAS Content Collection data for recent publications (since 2012). This article aims to explore the intricate landscape of antibacterial research while reviewing the advancement from traditional antibiotics to novel and emerging antibacterial strategies. By delving into the resistance mechanisms, this paper highlights the need to find alternate strategies to address the growing concern.

Advancements in Synthetic Strategies and Biological Effects of Ciprofloxacin Derivatives: A Review

Ciprofloxacin is a widely used antibiotic in the fluoroquinolone class. It is widely acknowledged by various researchers worldwide, and it has been documented to have a broad range of other pharmacological activities, such as anticancer, antiviral, antimalarial activities, etc. Researchers have been exploring the synthesis of ciprofloxacin derivatives with enhanced biological activities or tailored capability to target specific pathogens. The various biological activities of some of the most potent and promising ciprofloxacin derivatives, as well as the synthetic strategies used to develop them, are thoroughly reviewed in this paper. Modification of ciprofloxacin via 4-oxo-3-carboxylic acid resulted in derivatives with reduced efficacy against bacterial strains. Hybrid molecules containing ciprofloxacin scaffolds displayed promising biological effects. The current review paper provides reported findings on the development of novel ciprofloxacin-based molecules with enhanced potency and intended therapeutic activities which will be of great interest to medicinal chemists.

Phenotypic and Genotypic Characterizations of Antimicrobial-Resistant Escherichia coli Isolates from Diverse Retail Meat Samples in North Carolina During 2018-2019

Surveillance of antimicrobial-resistant pathogens in U.S. retail meats is conducted to identify potential risks of foodborne illness. In this study, we conducted a phenotypic and genotypic analysis of Escherichia coli recovered from a diverse range of retail meat types during 2018-2019 in North Carolina. The investigation was conducted as part of the National Antimicrobial Resistance Monitoring System (NARMS). Retail meat sampling and E. coli isolation were performed in accordance with NARMS retail meat isolation protocols. We used the Sensititre™ broth microdilution system to determine phenotypic resistance to 14 antimicrobial agents and the Illumina next-generation sequencing platform for genotypic resistance profiling. The highest prevalence of E. coli isolates was found in ground turkey (n = 57, 42.9%) and chicken (n = 27, 20.3%), followed by ground beef (n = 25, 18.9%) and pork (n = 24, 18%). The isolates were divided into seven different phylogroups using the Clermont typing tool, with B1 (n = 59, 44.4%) and A (n = 39, 29.3%) being the most dominant, followed by B2 (n = 14, 10.5%), D (n = 7, 5.3%), F (n = 6, 4.5%), E (n = 3, 2.3%), and C (n = 2, 1.5%). Using multilocus sequence typing (MLST), 128 Sequence types (STs) were identified indicating high diversity. Phenotypic and genotypic resistance was observed toward aminoglycosides, sulfonamides, beta-lactams, macrolides, tetracyclines, phenicols, and fluoroquinolones. Ground turkey samples were more resistant to the panel of tested antimicrobials than chicken, beef, or pork (p < 0.05). All isolates were found to be susceptible to meropenem. A high percentage of turkey isolates (n = 16, 28%) were multidrug-resistant (MDR) compared with 18.5% of chicken (n = 5), 8.4% of pork (n = 2), and 8% of beef isolates (n = 2). This study highlights the benefit of surveillance to identify MDR E. coli for epidemiologic tracking and is a comprehensive report of the phenotypic and genotypic characterization of E. coli isolated from retail meats in North Carolina.

''Myth Busting in Infectious Diseases'': A Comprehensive Review

Antibiotics have played a pivotal role in modern medicine, drastically reducing mortality rates associated with bacterial infections. Despite their significant contributions, the emergence of antibiotic resistance has become a formidable challenge, necessitating a re-evaluation of antibiotic use practices. The widespread belief in clinical practice that bactericidal antibiotics are inherently superior to bacteriostatic ones lacks consistent support from evidence in randomized controlled trials (RCTs). With the latest evidence, certain infections have demonstrated equal or even superior efficacy with bacteriostatic agents. Furthermore, within clinical practice, there is a tendency to indiscriminately order urine cultures for febrile patients, even in cases where alternative etiologies might be present. Consequently, upon obtaining a positive urine culture result, patients often receive antimicrobial prescriptions despite the absence of clinical indications warranting such treatment. Furthermore, it is a prevailing notion among physicians that extended durations of antibiotic therapy confer potential benefits and mitigate the emergence of antimicrobial resistance. Contrary to this belief, empirical evidence refutes such assertions. This article aims to address common myths and misconceptions within the field of infectious diseases.

Pattern of prescriptions and prudent use of antimicrobial in horse practice at a Veterinary Teaching Hospital

Antimicrobial prescriptions of the University of Pisa and their compliance with prudent use recommendations were investigated over 11 years (2011-2021). At least one antimicrobial was always prescribed in surgical prophylaxis for the suture of wounds and in 33% of horses with signs of disease of a body system. Antimicrobials were administered in monotherapy (48%) in fixed dose combinations (21%) and empirical combinations (31%). Antimicrobials were mostly (63%) administered by parenteral route, while oral and topical antimicrobials accounted for 14% and 23% of prescriptions, respectively. Gentamicin, benzylpenicillin and ceftiofur were the most prescribed antimicrobials; aminoglycosides, penicillins and cephalosporins were the most common class of antimicrobial prescribed. Protected antimicrobials (WHO HPCIA and rifampicin) represented 24% of antimicrobial dispensations. The pattern of classes of antimicrobial used by body system was broad and included up to eight different pharmaceutical classes. The heterogeneity of antimicrobial use was confirmed by the estimate of the prescription diversity index. Antimicrobial prescriptions were in compliance with prudent use recommendations in terms of availability of diagnosis, respect of the dose range and duration of treatment On the contrary, principles of appropriate antimicrobial use have only been partially observed in relation to off-label use, use of antimicrobials in empirical combination, use of antimicrobial susceptibility tests and use of protected antimicrobials, suggesting that additional interventions are required to improve the responsible use of antimicrobials use in our equine practice.

Efficacy of new generation biosorbents for the sustainable treatment of antibiotic residues and antibiotic resistance genes from polluted waste effluent

Antimicrobials are frequently used in both humans and animals for the treatment of bacterially-generated illnesses. Antibiotic usage has increased for more than 40% from last 15 years globally per day in both human populations and farm animals leading to the large-scale discharge of antibiotic residues into wastewater. Most antibiotics end up in sewer systems, either directly from industry or healthcare systems, or indirectly from humans and animals after being partially metabolized or broken down following consumption. To prevent additional antibiotic compound pollution, which eventually impacts on the spread of antibiotic resistance, it is crucial to remove antibiotic residues from wastewater. Antibiotic accumulation and antibiotic resistance genes cannot be effectively and efficiently eliminated by conventional sewage treatment plants. Because of their high energy requirements and operating costs, many of the available technologies are not feasible. However, the biosorption method, which uses low-cost biomass as the biosorbent, is an alternative technique to potentially address these problems. An extensive literature survey focusing on developments in the field was conducted using English language electronic databases, such as PubMed, Google Scholar, Pubag, Google books, and ResearchGate, to understand the relative value of the available antibiotic removal methods. The predominant techniques for eliminating antibiotic residues from wastewater were categorized and defined by example. The approaches were contrasted, and the benefits and drawbacks were highlighted. Additionally, we included a few antibiotics whose removal from aquatic environments has been the subject of extensive research. Lastly, a few representative publications were identified that provide specific information on the removal rates attained by each technique. This review provides evidence that biosorption of antibiotic residues from biological waste using natural biosorbent materials is an affordable and effective technique for eliminating antibiotic residues from wastewater.

A comprehensive review on the preparation of biochar from digestate sources and its application in environmental pollution remediation

The preparation of biochar from digestate is one of the effective ways to achieve the safe disposal and resource utilization of digestate. Nevertheless, up to now, a comprehensive review encompassing the factors influencing anaerobic digestate-derived biochar production and its applications is scarce in the literature. Therefore, to fill this gap, the present work first outlined the research hotspots of digestate in the last decade using bibliometric statistical analysis with the help of VOSviewer. Then, the characteristics of the different sources of digestate were summarized. Furthermore, the influencing factors of biochar preparation from digestate and the modification methods of digestate-derived biochar and associated mechanisms were analyzed. Notably, a comprehensive synthesis of anaerobic digestate-derived biochar applications is provided, encompassing enhanced anaerobic digestion, heavy metal remediation, aerobic composting, antibiotic/antibiotic resistance gene removal, and phosphorus recovery from digestate liquor. The economic and environmental impacts of digestate-derived biochar were also analyzed. Finally, the development prospect and challenges of using biochar from digestate to combat environmental pollution are foreseen. The aim is to not only address digestate management challenges at the source but also offer a novel path for the resourceful utilization of digestate.

Combating antimicrobial resistance: the silent war

Once hailed as miraculous solutions, antibiotics no longer hold that status. The excessive use of antibiotics across human healthcare, agriculture, and animal husbandry has given rise to a broad array of multidrug-resistant (MDR) pathogens, posing formidable treatment challenges. Antimicrobial resistance (AMR) has evolved into a pressing global health crisis, linked to elevated mortality rates in the modern medical era. Additionally, the absence of effective antibiotics introduces substantial risks to medical and surgical procedures. The dwindling interest of pharmaceutical industries in developing new antibiotics against MDR pathogens has aggravated the scarcity issue, resulting in an exceedingly limited pipeline of new antibiotics. Given these circumstances, the imperative to devise novel strategies to combat perilous MDR pathogens has become paramount. Contemporary research has unveiled several promising avenues for addressing this challenge. The article provides a comprehensive overview of these innovative therapeutic approaches, highlighting their mechanisms of action, benefits, and drawbacks.

Photodynamic inactivation of methicillin-resistant Staphylococcus aureus by using Giemsa dye as a photosensitizer

The rise of antibiotic-resistant bacteria calls for innovative approaches to combat multidrug-resistant strains. Here, the potential of the standard histological stain, Giemsa, to act as a photosensitizer (PS) for antimicrobial photodynamic inactivation (aPDI) against methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) strains is reported. Bioassays were performed using various Giemsa concentrations (ranging from 0.0 to 20.0 µM) under 625 nm illumination at a light dose of 30 J cm-2. Remarkably, Giemsa completely inhibited the growth of MSSA and MRSA bacterial colonies for concentrations at 10 µM and higher but exhibited no inhibitory effect without light exposure. Partition coefficient analysis revealed Giemsa's affinity for membranes. Furthermore, we quantified the production of reactive oxygen species (ROS) and singlet oxygen (1O2) to elucidate the aPDI mechanisms underlying bacterial inactivation mediated by Giemsa. These findings highlight Giemsa stain's potential as a PS in aPDI for targeting multidrug-resistant bacteria.

Recent Advances in the Development of Antibiotics-Coated Gold Nanoparticles to Combat Antimicrobial Resistance

Antimicrobial resistance (AMR) has become an alarming threat to the successful treatment of rapidly growing bacterial infections due to the abuse and misuse of antibiotics. Traditional antibiotics bear many limitations, including restricted bioavailability, inadequate penetration and the emergence of antimicrobial-resistant microorganisms. Recent advances in nanotechnology for the introduction of nanoparticles with fascinating physicochemical characteristics have been predicted as an innovative means of defence against antimicrobial-resistant diseases. The use of nanoparticles provides several benefits, including improved tissue targeting, better solubility, improved stability, enhanced epithelial permeability and causes minimal side effects. However, except for gold nanoparticles (AuNPs), the biological safety of the majority of metal nanoparticles remains a serious problem. AuNPs appear to be promising for drug delivery and medicinal applications because of their minimal toxicity, biocompatibility, functional flexibility, chemical stability and versatile biological activities, such as their antiviral, antifungal, anti-inflammatory and antimicrobial properties. Hence, we are focusing on the gold nanoparticles possessing antimicrobial activity in this article. This review will cover recent strategies in the preparation of gold nanoparticles, with special emphasis placed on antibiotics-coated AuNPs with enhanced antimicrobial properties and how they fight against disease-causing bacteria and eradicate biofilms, along with their activities and physicochemical properties.

A novel multifunctional magnetically recyclable BiOBr/ZnFe2O4-GO S-scheme ternary heterojunction: Photothermal synergistic catalysis under Vis/NIR light and NIR-driven photothermal detection of tetracycline

The threat of tetracycline (TC) to human health has become a significant issue that cannot be disregarded. Herein, in order to achieve effective degradation and high-sensitivity detection of TC, BiOBr/ZnFe2O4-GO (BOB/ZFO-GO) S-scheme heterojunction nanocomposites (NCs) have been prepared using hydrothermal method. GO with high light absorption capacity accelerated the electron transfer between BiOBr and ZnFe2O4 nanocrystals and extended the light absorption region of BOB/ZFO NCs. The optimal GO addition of BOB/ZFO-GO NCs could degrade TC solution of 10 mg/L in 80 min and have a high reaction rate constant (k) of 0.072 min-1 under visible/NIR light. According to calculations, the non-metal photocatalyst (BOB/ZFO-GO(2)) with the best degradation performance had a photothermal conversion efficiency of up to 23%. Meanwhile, BOB/ZFO-GO NCs could be recycled by magnetic field. The excellent photocatalytic and photothermal performance could be maintained even after several cycles. In addition, a photothermal detection sensor based on a photothermal material/specific recognition element/tetracycline sandwich-type structure was constructed for the trace detection of TC concentration with a detection limit as low as 10-4 ng/mL. This research provides a unique idea for the multi-functionalization of photocatalysts and has a wide range of potential applications for the identification and treatment of organic wastewater.

Investigating the Role of Metabolism for Antibiotic Combination Therapies in Pseudomonas aeruginosa

Antibacterial resistance poses a severe threat to public health; an anticipated 14-fold increase in multidrug-resistant (MDR) bacterial infections is expected to occur by 2050. Contrary to antibiotics, combination therapies are the standard of care for antiviral and anticancer treatments, as synergistic drug-drug interactions can decrease dosage and resistance development. In this study, we investigated combination treatments of a novel succinate dehydrogenase inhibitor (promysalin) with specific inhibitors of metabolism and efflux alongside a panel of clinically approved antibiotics in synergy studies. Through these investigations, we determined that promysalin can work synergistically with vancomycin and antagonistically with aminoglycosides and a glyoxylate shunt pathway inhibitor at subinhibitory concentrations; however, these cooperative effects do not reduce minimum inhibitory concentrations. The variability of these results underscores the complexity of targeting metabolism for combination therapies in antibiotic development.

Aqueous chemistry of nalidixic acid and its complexes with biological relevant cations: A combination of potentiometric, UV spectrophotometric, MS and MS/MS study

Nalidixic acid (NAL) is a broad-spectrum antimicrobial widely used for urinary tract infections. As demonstrated, complexation of NAL with Zn2+, Mn2+ and Cu2+ was often used to get new formulations with an enhanced efficiency and potency. Therefore, the elucidation of behavior of NAL in solution and of its interaction with metal cations are crucial to better understand the influence of complexation on NAL efficiency and to find the optimal conditions to propose novel formulations. As a preliminary study, spectrophotometric titrations were carried out on NAL to determine the values of the protonation constants and to define its acid-base behavior. Then, the interaction with the three metal cations Zn2+, Mn2+ and Cu2+ was investigated by potentiometric and spectrophotometric titrations, varying the conditions of temperature, ionic strength and metal-ligand ratio, thus allowing to get the most robust speciation model and to determine the formation constants with Zn2+, Mn2+, and Cu2+ under different conditions, the sequestering ability of NAL towards metal cations, the formation enthalpic and entropic changes. A simulation under serum conditions was reported to show the relevance of the investigated species. Finally, LD-MS (laser desorption ionization mass spectrometry) and MS/MS analyses highlighted for all systems the formation of the complex species between Zn2+, Mn2+ and Cu2+ with NAL. MS/MS investigations assigned the sites of coordination of the ligand with the metal cation. More precisely, deprotonated NAL coordinates the metal cation via the oxygens of the carboxylate and the carbonyl groups.

Medical treatment of pleural infection: antibiotic duration and corticosteroid usefulness

The data about the optimal duration of antibiotics and the usefulness of corticosteroids in the management of parapneumonic effusion and pleural infection are scarce. Two randomised controlled trials evaluating short antibiotic courses (ODAPE and SLIM) and another trial assessing the benefit from corticosteroid use (STOPPE) in this setting were recently published. The aim of this journal club is to present these trials and discuss their significance and limitations. ODAPE compared the efficacy and safety of a short (2 weeks) versus an extended (3 weeks) course of amoxicillin-clavulanate in community-acquired complicated parapneumonic effusions, while SLIM compared the efficacy and safety of short (14-21 days) versus longer (28-42 days) antibiotic courses in patients with community- or hospital-acquired pleural infection. STOPPE assessed the benefit from dexamethasone use in patients with community-acquired pneumonia and concomitant pleural effusion. Both ODAPE and SLIM found that shorter antibiotic courses produce less adverse events while being equally efficacious to the longer courses in a subgroup of patients, such as those with pleural infection that is stabilised with only medical treatment and does not require surgery. In contrast, STOPPE found no benefit from the use of dexamethasone in unselected patients with pneumonia and pleural effusion. Due to the significant limitations of these trials, further studies are required to confirm these findings.

Commentary on

Hassan M, et al. The Short versus Long Antibiotic Course for Pleural Infection Management (SLIM) randomised controlled open-label trial. ERJ Open Res 2023; 9: 00635-2022.Porcel JM, et al. Two vs. three weeks of treatment with amoxicillin-clavulanate for stabilized community-acquired complicated parapneumonic effusions. A preliminary non-inferiority, double-blind, randomized, controlled trial. Pleura Peritoneum 2020; 5: 20190027.Fitzgerald DB, et al. Steroid Therapy and Outcome of Parapneumonic Pleural Effusions (STOPPE): a pilot randomized clinical trial. Am J Respir Crit Care Med 2022; 205: 1093-1101.

Origin of Antibiotics and Antibiotic Resistance, and Their Impacts on Drug Development: A Narrative Review

Antibiotics have revolutionized medicine, saving countless lives since their discovery in the early 20th century. However, the origin of antibiotics is now overshadowed by the alarming rise in antibiotic resistance. This global crisis stems from the relentless adaptability of microorganisms, driven by misuse and overuse of antibiotics. This article explores the origin of antibiotics and the subsequent emergence of antibiotic resistance. It delves into the mechanisms employed by bacteria to develop resistance, highlighting the dire consequences of drug resistance, including compromised patient care, increased mortality rates, and escalating healthcare costs. The article elucidates the latest strategies against drug-resistant microorganisms, encompassing innovative approaches such as phage therapy, CRISPR-Cas9 technology, and the exploration of natural compounds. Moreover, it examines the profound impact of antibiotic resistance on drug development, rendering the pursuit of new antibiotics economically challenging. The limitations and challenges in developing novel antibiotics are discussed, along with hurdles in the regulatory process that hinder progress in this critical field. Proposals for modifying the regulatory process to facilitate antibiotic development are presented. The withdrawal of major pharmaceutical firms from antibiotic research is examined, along with potential strategies to re-engage their interest. The article also outlines initiatives to overcome economic challenges and incentivize antibiotic development, emphasizing international collaborations and partnerships. Finally, the article sheds light on government-led initiatives against antibiotic resistance, with a specific focus on the Middle East. It discusses the proactive measures taken by governments in the region, such as Saudi Arabia and the United Arab Emirates, to combat this global threat. In the face of antibiotic resistance, a multifaceted approach is imperative. This article provides valuable insights into the complex landscape of antibiotic development, regulatory challenges, and collaborative efforts required to ensure a future where antibiotics remain effective tools in safeguarding public health.

Enzymatic Antimicrobial Susceptibility Testing with Bacteria Identification in 30 min

Rapid antimicrobial susceptibility testing (AST) with the ability of bacterial identification is urgently needed for evidence-based antibiotic prescription. Herein, we propose an enzymatic AST (enzyAST) that employs β-d-glucuronidase as a biomarker to identify pathogens and profile phenotypic susceptibilities simultaneously. EnzyAST enables to offer binary AST results within 30 min, much faster than standard methods (>16 h). The general applicability of enzyAST was verified by testing the susceptibility of two Escherichia coli strains to three antibiotics with different action mechanisms. The pilot study also shows that the minimal inhibitory concentrations can be determined by enzyAST with the statistical analysis of enzymatic activity of the bacteria population exposed to varying antibiotic concentrations. With further development of multiple bacteria and sample treatment, enzyAST could be able to evaluate the susceptibility of pathogens in clinical samples directly to facilitate the evidence-based therapy.

Heterocyclic pyrimidine derivatives as promising antibacterial agents

Antibiotic resistance is a growing public health concern. The quest to understand the underlying mechanisms of drug resistance needs to be accompanied by an expanded arsenal of drugs. This calls for the development of new compounds with anti-bacterial properties. The ease of functionalization of the pyrimidine core, to produce structurally distinct compound libraries, has made pyrimidine a privileged structure for identifying anti-bacterial hits. The activity of pyrimidine derivatives can be attributed to the various subunits linked with the main core, especially at C-2 or C-4 or C-6. Particularly, presence of NH2 attached to C-2 of the pyrimidine nucleus has been shown to enhance the anti-bacterial activity against pathogenic Gram-positive and Gram-negative bacteria. The diversity of synthetic routes used for the synthesis of such compounds, the reported biological activities, and a growing need to develop novel anti-bacterial agents warrant a review that presents recent reports on the synthesis and anti-bacterial activities of pyrimidine-containing compounds.

Can Antibiotic Stewardship Be Achieved by Utilizing the Stewardship Through Educating Patients (S.T.E.P.) Process?

BACKGROUND

Despite research and efforts to mitigate bacterial resistance, antibiotic overprescribing continues to occur, often due to real or perceived expectations of patients.  Objective: The purpose of this study was to determine: (1) if there's an association between the provider's patient education efforts and the patient's satisfaction, and (2) the research participant's subsequent behavior concerning antibiotic prescriptions, by utilizing the Stewardship Through Educating Patients (S.T.E.P.) process for positive prescriptive change. The S.T.E.P. program features straightforward, simple education via face-to-face counseling at patient encounters, along with presenting applicable printed educational pamphlets from the Centers for Disease Control and Prevention (CDC). These two interventions were utilized in this study with research participants from the healthcare provider, with education focused on appropriate antibiotic use in the treatment of adults diagnosed with common illnesses such as an upper respiratory infection (the common cold), acute sinusitis, and acute bronchitis, which oftentimes are viral in origin.

METHOD

This Quality Improvement (QI) interventional study utilized the researcher's direct face-to-face patient education and CDC printed materials as a measure of antibiotic prescribing as a primary outcome, with patient satisfaction as a secondary outcome via convenience sampling of 40 hospital employees who utilized a free hospital-based employee healthcare clinic.

RESULTS

Patient-teaching by this study's researcher, along with supplemental printed patient education material from the CDC that were given to research participants during an initial medical encounter, were effective interventions used in reducing antibiotic prescribing, as evidenced by a positive patient satisfaction in 95% of research participants.

CONCLUSIONS

Antibiotic use in the treatment of adults diagnosed with common illnesses such as an upper respiratory infection (the common cold), acute sinusitis, and acute bronchitis, may be safely reduced by using a combination of patient-education and clinician intervention.

Trimethoprim resistance in surface and wastewater is mediated by contrasting variants of the dfrB gene

Trimethoprim (TMP) is a low-cost, widely prescribed antibiotic. Its effectiveness is increasingly challenged by the spread of genes coding for TMP-resistant dihydrofolate reductases: dfrA, and the lesser-known, evolutionarily unrelated dfrB. Despite recent reports of novel variants conferring high level TMP resistance (dfrB10 to dfrB21), the prevalence of dfrB is still unknown due to underreporting, heterogeneity of the analyzed genetic material in terms of isolation sources, and limited bioinformatic processing. In this study, we explored a coherent set of shotgun metagenomic sequences to quantitatively estimate the abundance of dfrB gene variants in aquatic environments. Specifically, we scanned sequences originating from influents and effluents of municipal sewage treatment plants as well as river-borne microbiomes. Our analyses reveal an increased prevalence of dfrB1, dfrB2, dfrB3, dfrB4, dfrB5, and dfrB7 in wastewater microbiomes as compared to freshwater. These gene variants were frequently found in genomic neighborship with other resistance genes, transposable elements, and integrons, indicating their mobility. By contrast, the relative abundances of the more recently discovered variants dfrB9, dfrB10, and dfrB13 were significantly higher in freshwater than in wastewater microbiomes. Moreover, their direct neighborship with other resistance genes or markers of mobile genetic elements was significantly less likely. Our findings suggest that natural freshwater communities form a major reservoir of the recently discovered dfrB gene variants. Their proliferation and mobilization in response to the exposure of freshwater communities to selective TMP concentrations may promote the prevalence of high-level TMP resistance and thus limit the future effectiveness of antimicrobial therapies.

Irrational use of antibiotics and factors associated with antibiotic resistance: Findings from a cross-sectional study in Bangladesh

Background and aims

Irrational antibiotic (AB) usage poses a serious concern to third-world countries because of poor surveillance, lack of information, and patients' propensity for self-medication. Additionally, the unpredictability of the coronavirus disease 2019 (COVID-19) pandemic promoted the abuse of ABs, which accelerated the prevalence of antibiotic resistance (ABR). The primary aim of this study was to assess the pattern of AB usage and irrational use of ABs-related potential factors associated with ABR among the students and teachers of a leading public university of Bangladesh.

Methods

A cross-sectional web-based survey was conducted among the students and teachers (n = 783) of the selected university, from January 1 to February 28, 2022. Descriptive statistics, χ ² test, and logistic regression analysis were employed to analyze the collected data.

Results

The regression analysis supported that male participants had a 34% lower experience of acquiring ABR than female respondents (adjusted odds ratio [AOR] = 0.66, 95% confidence interval [CI] = 0.448, 0.973; p = 0.036). The 1st/2nd-year level students had more than two times higher experience with ABR than the master's or higher-class students (AOR = 2.149, 95% CI = 1.047, 4.412; p = 0.037). The participants who took ABs for 4-6 days showed more than two times ABR experience than those who took ABs for above 10 days (AOR = 2.016, 95% CI = 1.016, 4.003; p = 0.045). Respondents who finished their AB medication (dose completion) had a 57% less chance of acquiring ABR than the participants who did not complete their dose.

Conclusion

This study found that irrational use of ABs is more prevalent among the youth and female participants. At this stage, there is an urgent need for comprehensive statutory AB control rules, as well as measures for appropriate information, education, and surveillance throughout different groups of Bangladesh.

Advances in the Applications of Bioinformatics and Chemoinformatics

Chemoinformatics involves integrating the principles of physical chemistry with computer-based and information science methodologies, commonly referred to as "in silico techniques", in order to address a wide range of descriptive and prescriptive chemistry issues, including applications to biology, drug discovery, and related molecular areas. On the other hand, the incorporation of machine learning has been considered of high importance in the field of drug design, enabling the extraction of chemical data from enormous compound databases to develop drugs endowed with significant biological features. The present review discusses the field of cheminformatics and proposes the use of virtual chemical libraries in virtual screening methods to increase the probability of discovering novel hit chemicals. The virtual libraries address the need to increase the quality of the compounds as well as discover promising ones. On the other hand, various applications of bioinformatics in disease classification, diagnosis, and identification of multidrug-resistant organisms were discussed. The use of ensemble models and brute-force feature selection methodology has resulted in high accuracy rates for heart disease and COVID-19 diagnosis, along with the role of special formulations for targeting meningitis and Alzheimer's disease. Additionally, the correlation between genomic variations and disease states such as obesity and chronic progressive external ophthalmoplegia, the investigation of the antibacterial activity of pyrazole and benzimidazole-based compounds against resistant microorganisms, and its applications in chemoinformatics for the prediction of drug properties and toxicity-all the previously mentioned-were presented in the current review.

Antibiotic sensitivity profile of bacterial isolates from stool samples among children below five years in Murang'a County, Kenya

Introduction

the discovery of antibiotics led to the optimistic belief of completely eradicating infectious diseases during the golden era following their discovery. Countries are grappling with the burden of microbial resistance bringing a near paralysis of all facets of mankind. Enterobacteriaceae and other hard-to-treat Gram-negative bacteria have become resistant to nearly all antibiotic options available, and this is a bad taste in the fight against microbial resistance.

Methods

during the months of April-October 2017, 163 children below five years presenting with diarrhea were randomly selected in Murang´a and Muriranja´s Hospitals. Bacterial agents were identified and antibiotic susceptibility profile was determined. Design: a cross-sectional study approach was used. Statistical analyses were performed using STATA v. 13.

Results

a total of 188 bacteria belonging to 11 genera were isolated, and identified and their antibiotic susceptibility profiles were determined. Susceptibility testing showed that almost all the Enterotoxigenic Escherichia coli (ETEC), Enteropathogenic Escherichia coli (EPEC), Enteroaggregative Escherichia coli (EAEC), Salmonella, Klebsiella, Shigella, Vibrio, Enterobacter, Proteus, Pseudomonas, Aeromonas, Citrobacter and Yersinia species were resistant to the following antibiotics: ampicillin, amoxicillin, chloramphenicol, ciprofloxacin, ceftriaxone and kanamycin. Other than ETEC (90.9%), all the rest of the isolates were resistant to nalidixic acid. Other than ETEC (9.1%), EAEC (33.3%) and Salmonella species (95.2%), all the rest of the isolates were resistant to gentamicin. Other than V. cholerae, all the other isolates were resistant to trimethoprim-sulfamethoxazole. Isolates were sporadically resistant to erythromycin, streptomycin, doxycycline, and ofloxacin.

Conclusion

the high resistance rate of enteric Gram-negative bacterial pathogens in Murang´a County is alarming. The need for urgent, efficient, and sustainable actions and interventions, such as culture and susceptibility testing, is needed and must be taken into account to minimize and prevent the establishment and spread of enteric pathogenic bacteria.

Mass spectrometric analysis of bioactive conditioned media of bacteria isolated from reptilian gut

Aim

To determine whether selected gut bacteria of crocodile exhibit antibacterial properties.

Materials & methods

Two bacteria isolated from Crocodylus porosus gut were used, namely: Pseudomonas aeruginosa and Aeromonas dhakensis. Conditioned media were tested against pathogenic bacteria and metabolites were analyzed using liquid chromatography-mass spectrometry.

Results & conclusion

Antibacterial assays revealed that conditioned media showed potent effects against pathogenic Gram-positive and Gram-negative bacteria. LC-MS revealed identity of 210 metabolites. The abundant metabolites were, N-Acetyl-L-tyrosine, Acetaminophen, Trans-Ferulic acid, N, N-Dimethylformamide, Pyrocatechol, Cyclohexanone, Diphenhydramine, Melatonin, Gamma-terpinene, Cysteamine, 3-phenoxypropionic acid, Indole-3-carbinol, Benzaldehyde, Benzocaine, 2-Aminobenzoic acid, 3-Methylindole. These findings suggest that crocodile gut bacteria are potential source of novel bioactive molecules that can be utilized as pre/post/antibiotics for the benefit of human health.

Combined Effect of Isolated Bacteriophage and Neem Extract on Isolated Multiple Drug-Resistant Pathogenic Escherichia coli E1 From Well Water

Multiple drug-resistant Escherichia coli (E. coli) is a serious cause of concern, and they can be observed in hospital settings, natural environment, and animals. Dissemination of multiple drug-resistant (MDR) E. coli can pose a high risk to public health. Moreover, they are hard to control with commercial antibiotics, since they have acquired resistance against most of them. Therefore, to control multiple drug-resistant bacteria, alternative strategies have been adopted such as phage therapy, herbal remedies, nanoparticles etc. In the current study, the combined application of neem leaf extract and bacteriophage is used to control an isolated multiple drug-resistant E. coli E1. We have applied 0.1 mg/ml concentration of neem extract in combination with an isolated phage vB_EcoM_C2 of 10¹¹ titer and found that the combinatorial treatment approach significantly controls the growth of E. coli E1 as compared to a single non-combinatorial treatment. In this study, every E. coli cell is targeted by 2 antimicrobials (phage and neem extract) at the same time, which is more effective as compared to the sole treatment. Implementation of the neem extract with phage opens a new alternative approach to the chemotherapeutics for the control of multiple drug-resistant bacterial pathogens. This approach may be effective, economical, and eco-friendly to combat MDR.

Prevalence and Antibiotic Resistance Pattern of Streptococcus, Staphylococcus, Neisseria meningitidis and Enterobacteriaceae in Two Reference Hospitals of Yaoundé: An Overview before and during COVID-19 Pandemic Era

The COVID-19 pandemic led to tremendously use of antimicrobial due to the lack of proper treatment strategies, raising concerns about emergence of antimicrobial resistance (AMR). This study aimed at determining the prevalence and antibiotic resistance pattern of selected bacteria isolates in 02 referral health facilities in Yaoundé before and during the COVID-19 pandemic era. We conducted a retrospective study over a period of 03 years (from 1 January 2019 to 31 December 2021) in the bacteriology units of the Central and General Hospitals of Yaoundé, Cameroon. Data on bacteria genera (Streptococcus, Staphylococcus, Neisseria meningitidis and Enterobacteriaceae) as well as their corresponding specifics antibiotics: Cefixime, azythromycin and erythromycin were obtained from laboratory records. The global resistance rate of bacteria as well as their correlation with antibiotics according to COVID-19 pandemic era was determined and compared. For p < 0.05, the difference was statistically significant. In all, 426 bacterial strains were included. It appeared that the highest number of bacteria isolates and lowest rate of bacterial resistance were recorded during the pre-COVID-19 period in 2019 (160 isolates vs. 58.8% resistance rate). Conversely, lower bacteria strains but greater resistance burden were recorded during the pandemic era (2020 and 2021) with the lowest bacteria amount and peak of bacteria resistance registered in 2020, the year of COVID-19 onset (120 isolates vs. 70% resistance in 2020 and 146 isolates vs. 58.9% resistance in 2021). In contrast to almost all others groups of bacteria where the resistance burden was quite constant or decreasing over years, the Enterobacteriaceae exhibited greater resistance rate during the pandemic period [60% (48/80) in 2019 to 86.9% (60/69) in 2020 and 64.5% (61/95) in 2021)]. Concerning antibiotics, unlike erythromycin, azythromycin related resitance increased during the pandemic period and the resistance to Cefixim tends to decrease the year of the pandemic onset (2020) and re-increase one year therafter. A significant association was found between resistant Enterobacteriaceae strains and cefixime (R = 0.7; p = 0.0001) and also, between resistant Staphylococcus strains and erythromycin (R = 0.8; p = 0.0001). These retrospective data showed a herogeneous MDR bacteria rate and antibiotic resistance pattern over time before and during the COVID-19 pandemic era suggesting that antimicrobial resistance needs to be more closely monitored.

Wastewater-based monitoring reveals geospatial-temporal trends for antibiotic-resistant pathogens in a large urban community

Antimicrobial resistance (AMR) is one of the top ten global health threats, and current surveillance programs rarely monitor it outside healthcare settings. This limits our ability to understand and manage the spread of AMR. Wastewater testing has the potential to simply, reliably and continuously survey trends in AMR outside the healthcare settings, as it captures biological material from the entire community. To establish and evaluate such a surveillance, we monitored wastewater for four clinically significant pathogens across the urban area of Greater Sydney, Australia. Untreated wastewater from 25 wastewater treatment plants (WWTPs) covering distinct catchment regions of 5.2 million residents was sampled between 2017 and 2019. Isolates for extended-spectrum β-lactamases-producing Enterobacteriaceae (ESBL-E) were consistently detected, suggesting its endemicity in the community. Isolates for carbapenem-resistant Enterobacteriaceae (CRE), vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA) were only occasionally detected. The flow normalized relative (FNR) ESBL-E load was positively correlated with the proportion of the population between 19 and 50 years of age, completion of vocational education and the average length of hospital stay. Collectively, these variables explained only a third of the variance of the FNR ESBL-E load, indicating further, yet-unidentified factors as a contributor to the distribution. About half of the variation in the FNR CRE load was explained by the average length of hospital stay, showing healthcare-related drivers. Interestingly, variation in the FNR VRE load was not correlated to healthcare-related parameters but to the number of schools per 10,000 population. Our study provides insight into how routine wastewater surveillance can be used to understand the factors driving the distribution of AMR in an urban community. Such information can help to manage and mitigate the emergence and spread of AMR in important human pathogens.

Recent developments in detection and therapeutic approaches for antibiotic-resistant bacterial infections

Owing to the widespread emergence and proliferation of antibiotic-resistant bacteria, the therapeutic benefits of antibiotics have been reduced. In addition, the ongoing evolution of multidrug-resistant pathogens poses a challenge for the scientific community to develop sensitive analytical methods and innovative antimicrobial agents for the detection and treatment of drug-resistant bacterial infections. In this review, we have described the antibiotic resistance mechanisms that occur in bacteria and summarized the recent developments in detection strategies for monitoring drug resistance using different diagnostic methods in three aspects, including electrostatic attraction, chemical reaction, and probe-free analysis. Additionally, to understand the effective inhibition of drug-resistant bacterial growth by recent nano-antibiotics, the underlying antimicrobial mechanisms and efficacy of biogenic silver nanoparticles and antimicrobial peptides, which have shown promise, and the rationale, design, and potential improvements to these methods are also highlighted in this review. Finally, the primary challenges and future trends in the rational design of facile sensing platforms and novel antibacterial agents against superbugs are discussed.

Physicians' attitudes, knowledge, and practices regarding antibiotic prescriptions

OBJECTIVES

Inappropriate and overuse of antimicrobials, incorrect dosing, and extended duration are some of the leading causes of antibiotic-resistance that have led to the development of antimicrobial resistance (AMR). We aimed to evaluate knowledge, attitudes, and practices regarding rational antibiotic prescribing among physicians in a teaching hospital in Oman, with the goal of identifying knowledge gaps and interventions that could lead to judicious use of antimicrobials and reduce the emergence of resistant organisms METHODS: A cross-sectional study assessing physicians' knowledge of and attitudes towards prescribing antibiotics was conducted at the Royal Hospital from 15 January to 31 March 2020. Likert scales were used to evaluate physicians' awareness and perception of personal performance regarding the care of patients with infections and rational use of antibiotics.

RESULTS

Inadequate hand washing was regarded as the most important factor contributing to AMR (51.6%), followed by widespread use of antibiotics (49%), prescribing broad-spectrum antibiotics (47.3%), lack of effective narrow-spectrum antibiotics (47.3%), inappropriate duration of antibiotic therapy (46.2%), inappropriate empirical choice of antibiotics (45.1%), poor access to information on local antibiotic resistance patterns (40.8%), and inadequate restrictions on antibiotic prescribing (34.4%). Other factors contributing to AMR such as lack of local hospital guidelines on antibiotic usage, random mutations in microbes, patient demands and expectations for antibiotics, and the role of pharmaceutical companies in advertising and promoting use of antibiotics were deemed important by 33.3%, 26.8%, 22.5% and 20.4%, respectively.

CONCLUSIONS

AMR is a global health threat with significant effect on the health system and the economy. Misuse and overuse of antimicrobials remain the main drivers for the development of drug-resistant pathogens. Identifying knowledge gaps and planning interventions that could lead to judicious use of antimicrobials including establishing an Antimicrobial Stewardship Program are of paramount importance in reducing AMR in the twenty-first century and beyond.

The biological role of charge distribution in linear antimicrobial peptides

INTRODUCTION

Antimicrobial peptides (AMP) have received particular attention due to their capacity to kill bacteria. Although much is known about them, peptides are currently being further researched. A large number of AMPs have been discovered, but only a few have been approved for topical use, due to their promiscuity and other challenges, which need to be overcome.

AREAS COVERED

AMPs are diverse in structure. Consequently, they have varied action mechanisms when targeting microorganisms or eukaryotic cells. Herein, the authors focus on linear peptides, particularly those that are alpha-helical structured, and examine how their charge distribution and hydrophobic amino acids could modulate their biological activity.

EXPERT OPINION

The world currently needs urgent solutions to the infective problems caused by resistant pathogens. In order to start the race for antimicrobial development from the charge distribution viewpoint, bioinformatic tools will be necessary. Currently, there is no software available that allows to discriminate charge distribution in AMPs and predicts the biological effects of this event. Furthermore, there is no software available that predicts the side-chain length of residues and its role in biological functions. More specialized software is necessary.

[Bacterial resistance, a current crisis.]

Bacterial resistance is a constant battle representing a Public Health trouble. So much, that the World Health Organization considerate Public Health as a priority in health, due to the impact that generates as much as in health (giving that recent projections indicate that by 2050 it'll be produced more deaths because of this than the ones occasioned because of cancer) as its economic impact (which, according to a recent study in the United Kingdom, it'll cost the world's economy an estimated of 100 trillion dollars). The quick appearance of multidrug-resistant and pandrug-resistant bacteria is a world nature phenomenon, questioning the antibiotics efficiency. Implement protocols and recommendations is essential, just as essential and necessary as give awareness to health personnel, taking as base the knowledge of resistance generation and its impact through the years, empowered by the actual pandemic of COVID 19.

Antimicrobial and Antiviral Compounds of Phlomis viscosa Poiret

Phlomis viscosa Poiret (an evergreen shrub) represents a valuable source of medicinal compounds. In this study, we discovered compounds with antimicrobial and antiviral properties. The aim of this study was to identify compounds of P. viscosa and estimate the antimicrobial and antiviral activity of its phytochemicals. The volatile compounds were identified using gas chromatography/mass spectrometry (GC/MS) analysis. For the identification of nonvolatile components of the extracts, high-performance liquid chromatography (HPLC), liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) were applied. Quercetin 3-O-rutinoside and hesperidin caused a significant decrease in the bacterial concentration of Agrobacterium tumefaciens, Xylella fastidiosa and Pseudomonas syringae (p < 0.001). The growth of drug-resistant microorganisms (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Serratia marcescens and Salmonella enteritidis) was inhibited by quercetin 3-O-rutinoside, quercetin 3-O-arabinoside and hesperidin. In addition, these compounds demonstrated antiquorum-sensing properties. Diosmin, hesperidin and quercetin 3-O-arabinoside significantly inhibited varicella zoster virus (VZV) (p < 0.001). Quercetin 3-O-rutinoside and quercetin 3-O-arabinoside were effective against herpes simplex virus 1 (HSV-1), including mutant strains.

Optical photothermal infrared spectroscopy: A novel solution for rapid identification of antimicrobial resistance at the single-cell level via deuterium isotope labeling

The rise and extensive spread of antimicrobial resistance (AMR) has become a growing concern, and a threat to the environment and human health globally. The majority of current AMR identification methods used in clinical setting are based on traditional microbiology culture-dependent techniques which are time-consuming or expensive to be implemented, thus appropriate antibiotic stewardship is provided retrospectively which means the first line of treatment is to hope that a broad-spectrum antibiotic works. Hence, culture-independent and single-cell technologies are needed to allow for rapid detection and identification of antimicrobial-resistant bacteria and to support a more targeted and effective antibiotic therapy preventing further development and spread of AMR. In this study, for the first time, a non-destructive phenotyping method of optical photothermal infrared (O-PTIR) spectroscopy, coupled with deuterium isotope probing (DIP) and multivariate statistical analysis was employed as a metabolic fingerprinting approach to detect AMR in Uropathogenic Escherichia coli (UPEC) at both single-cell and population levels. Principal component-discriminant function analysis (PC-DFA) of FT-IR and O-PTIR spectral data showed clear clustering patterns as a result of distinctive spectral shifts (C-D signature peaks) originating from deuterium incorporation into bacterial cells, allowing for rapid detection and classification of sensitive and resistant isolates at the single-cell level. Furthermore, the single-frequency images obtained using the C-D signature peak at 2,163 cm^-1 clearly displayed the reduced ability of the trimethoprim-sensitive strain for incorporating deuterium when exposed to this antibiotic, compared to the untreated condition. Hence, the results of this study indicated that O-PTIR can be employed as an efficient tool for the rapid detection of AMR at the single-cell level.

Are postoperative antibiotics required after orthognathic surgery?

The aim of this study was to investigate and compare the frequency of surgical site infection (SSI) between orthognathic patients who received only intraoperative antibiotics and patients who received intraoperative antibiotics plus postoperative antibiotics. A retrospective study was performed of patients treated by a single surgeon over the years 2006-2012 and 2016-2019. The primary predictor variable was antibiotic exposure. The control group received no postoperative prophylactic antibiotics. The study group received postoperative antibiotics. Both groups received prophylactic intraoperative antibiotics and performed postoperative chlorhexidine rinses. The primary outcome was SSI frequency. Univariate, bivariate, and multiple logistic regression analyses were performed; statistical significance was set at P ≤ 0.05. The sample comprised 333 patients. Their mean age was 30.7 ± 11.8 years. The study group included 129 patients (38.7%); the control group included 204 patients (61.3%). The frequency of SSI was 17.1% in the study group and 26.5% in the control group (P = 0.048). In the multivariable logistic regression, only alcohol consumption was significantly associated with an increased risk of SSI (odds ratio 2.46, 95% confidence interval 1.36-4.44; P = 0.003). In patients undergoing orthognathic surgery, postoperative antibiotic exposure in addition to intraoperative prophylaxis approached but was not statistically significant for a decreased risk of SSI (P = 0.067).

The Diversity of Escherichia coli Pathotypes and Vaccination Strategies against This Versatile Bacterial Pathogen

Escherichia coli (E. coli) is a gram-negative bacillus and resident of the normal intestinal microbiota. However, some E. coli strains can cause diseases in humans, other mammals and birds ranging from intestinal infections, for example, diarrhea and dysentery, to extraintestinal infections, such as urinary tract infections, respiratory tract infections, meningitis, and sepsis. In terms of morbidity and mortality, pathogenic E. coli has a great impact on public health, with an economic cost of several billion dollars annually worldwide. Antibiotics are not usually used as first-line treatment for diarrheal illness caused by E. coli and in the case of bloody diarrhea, antibiotics are avoided due to the increased risk of hemolytic uremic syndrome. On the other hand, extraintestinal infections are treated with various antibiotics depending on the site of infection and susceptibility testing. Several alarming papers concerning the rising antibiotic resistance rates in E. coli strains have been published. The silent pandemic of multidrug-resistant bacteria including pathogenic E. coli that have become more difficult to treat favored prophylactic approaches such as E. coli vaccines. This review provides an overview of the pathogenesis of different pathotypes of E. coli, the virulence factors involved and updates on the major aspects of vaccine development against different E. coli pathotypes.

β-LacFamPred: An online tool for prediction and classification of β-lactamase class, subclass, and family

β-Lactams are a broad class of antimicrobial agents with a high safety profile, making them the most widely used class in clinical, agricultural, and veterinary setups. The widespread use of β-lactams has induced the extensive spread of β-lactamase hydrolyzing enzymes known as β-lactamases (BLs). To neutralize the effect of β-lactamases, newer generations of β-lactams have been developed, which ultimately led to the evolution of a highly diverse family of BLs. Based on sequence homology, BLs are categorized into four classes: A-D in Ambler's classification system. Further, each class is subdivided into families. Class B is first divided into subclasses B1-B3, and then each subclass is divided into families. The class to which a BL belongs gives a lot of insight into its hydrolytic profile. Traditional methods of determining the hydrolytic profile of BLs and their classification are time-consuming and require resources. Hence we developed a machine-learning-based in silico method, named as β-LacFamPred, for the prediction and annotation of Ambler's class, subclass, and 96 families of BLs. During leave-one-out cross-validation, except one all β-LacFamPred model HMMs showed 100% accuracy. Benchmarking with other BL family prediction methods showed β-LacFamPred to be the most accurate. Out of 60 penicillin-binding proteins (PBPs) and 57 glyoxalase II proteins, β-LacFamPred correctly predicted 56 PBPs and none of the glyoxalase II sequences as non-BLs. Proteome-wide annotation of BLs by β-LacFamPred showed a very less number of false-positive predictions in comparison to the recently developed BL class prediction tool DeepBL. β-LacFamPred is available both as a web-server and standalone tool at http://proteininformatics.org/mkumar/blacfampred and GitHub repository https://github.com/mkubiophysics/B-LacFamPred respectively.

Preventive effect of Terminalia bellirica (Gaertn.) Roxb. extract on mice infected with Salmonella Typhimurium

Terminalia bellirica (Gaertn.) Roxb. (TB) is a traditional herbal combination used in Chinese medicine for the treatment of a broad range of diseases. In this study, thirty KM mice were randomly divided into control (N), infection group (NS), and the TB protection group (HS). Based on its digestive feature, intestinal physical barrier, immunological barrier and gut microbiota effects in vivo on challenged with S.typhimurium mice were investigated after oral administration of 600 mg/kg b.wt of TB for 13 days. The results show that the extract could improve the level of serum immunoglobulins (IgA and IgG), decrease the intestinal cytokine secretion to relieve intestinal cytokine storm, reinforce the intestinal biochemical barrier function by elevating the sIgA expression, and strengthen the intestinal physical barrier function. Simultaneously, based on the V3-V4 region of the 16S rRNA analyzed, the results of the taxonomic structure of the intestinal microbiota demonstrated that the TB prevention effect transformed the key phylotypes of the gut microbiota in S. Typhimurium-challenged mice and promoted the multiplication of beneficial bacteria. Furthermore, the abundance of Firmicutes and Deferribacteres increased, while that of Bacteroidetes and Actinobacteria decreased. At the genus level, the abundance of Ruminococcus and Oscillospira was substantially enhanced, while the other dominant genera showed no significant change between the vehicle control groups and the TB prevention groups. In summary, these results provide evidence that the administration of TB extract can prevent S. Typhimurium infection by alleviating the intestinal physical and immunological barriers and normalizing the gut microbiota, highlighting a promising application in clinical treatment. Thus, our results provide new insights into the biological functions of TB for the preventive effect of intestinal inflammation.

Antifungal effects and biocontrol potential of lipopeptide-producing Streptomyces against banana Fusarium wilt fungus Fusarium oxysporum f. sp. cubense

Fusarium wilt of banana (FWB), caused by Fusarium oxysporum f. sp. cubense (Foc), especially tropical race 4 (TR4), presents the foremost menace to the global banana production. Extensive efforts have been made to search for efficient biological control agents for disease management. Our previous study showed that Streptomyces sp. XY006 exhibited a strong inhibitory activity against several phytopathogenic fungi, including F. oxysporum. Here, the corresponding antifungal metabolites were purified and determined to be two cyclic lipopeptide homologs, lipopeptin A and lipopeptin B. Combined treatment with lipopeptin complex antagonized Foc TR4 by inhibiting mycelial growth and conidial sporulation, suppressing the synthesis of ergosterol and fatty acids and lowering the production of fusaric acid. Electron microscopy observation showed that lipopeptide treatment induced a severe disruption of the plasma membrane, leading to cell leakage. Lipopeptin A displayed a more pronounced antifungal activity against Foc TR4 than lipopeptin B. In pot experiments, strain XY006 successfully colonized banana plantlets and suppressed the incidence of FWB, with a biocontrol efficacy of up to 87.7%. Additionally, XY006 fermentation culture application improved plant growth parameters and induced peroxidase activity in treated plantlets, suggesting a possible role in induced resistance. Our findings highlight the potential of strain XY006 as a biological agent for FWB, and further research is needed to enhance its efficacy and mode of action in planta.

The Phenomenon of Antibiotic Resistance in the Polar Regions: An Overview of the Global Problem

The increasing prevalence of antibiotic resistance is a global problem in human and animal health. This leads to a reduction in the therapeutic effectiveness of the measures used so far and to the limitation of treatment options, which may pose a threat to human health and life. The problem of phenomenon of antibiotic resistance affects more and more the polar regions. This is due to the increase in tourist traffic and the number of people staying at research stations, unmodernised sewage systems in inhabited areas, as well as the migration of animals or the movement of microplastics, which may contain resistant bacteria. Research shows that the presence of antibiotic resistance genes is more dominant in zones of human and wildlife influence than in remote areas. In a polluted environment, there is evidence of a direct correlation between human activity and the spread and survival of antibiotic-resistant bacteria. Attention should be paid to the presence of resistance to synthetic and semi-synthetic antibiotics in the polar regions, which is likely to be correlated with human presence and activity, and possible steps to be taken. We need to understand many more aspects of this, such as bacterial epigenetics and environmental stress, in order to develop effective strategies for minimizing the spread of antibiotic resistance genes. Studying the diversity and abundance of antibiotic resistance genes in regions with less anthropogenic activity could provide insight into the diversity of primary genes and explain the historical evolution of antibiotic resistance.

Non-caloric artificial sweeteners modulate conjugative transfer of multi-drug resistance plasmid in the gut microbiota

Non-caloric artificial sweeteners have been widely permitted as table sugar substitutes with high intensities of sweetness. They can pass through the intestinal tract without significant metabolization and frequently encounter the gut microbiome, which is composed of diverse bacterial species and is a pool of antibiotic resistance genes (ARGs). However, little is known about whether these sweeteners could accelerate the spread of ARGs in the gut microbiome. Here, we established an in vitro conjugation model by using Escherichia coli that carries chromosome-inserted Tn7 lacI^q-pLpp-mCherry and plasmid-encoded gfpmut3b gene as the donor and murine fecal bacteria as the recipient. We found that four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) can increase reactive oxygen species (ROS) production and promote plasmid-mediated conjugative transfer to the gut microbiome. Cell sorting and 16S rRNA gene amplicon sequencing analysis of fecal samples reveal that the tested sweeteners can promote the broad-host-range plasmid permissiveness to both Gram-negative and Gram-positive gut bacteria. The increased plasmid permissiveness was also validated with a human pathogen Klebsiella pneumoniae. Collectively, our study demonstrates that non-caloric artificial sweeteners can induce oxidative stress and boost the plasmid-mediated conjugative transfer of ARGs among the gut microbiota and a human pathogen. Considering the soaring consumption of these sweeteners and the abundance of mobile ARGs in the human gut, our results highlight the necessity of performing a thorough risk assessment of antibiotic resistance associated with the usage of artificial sweeteners as food additives.

All-In-One Escherichia coli Viability Assay for Multi-dimensional Detection of Uncomplicated Urinary Tract Infections

The urinary tract infections by antibiotic-resistant bacteria have been a serious public health problem and increase the healthcare costs. The conventional technologies of diagnosis and antimicrobial susceptibility testing (AST) relying on multiple culture-based assays are time-consuming and labor-intensive and thus compel the empirical antimicrobial therapies to be prescribed, fueling the prevalence of antimicrobial resistance. Herein, we propose an all-in-one Escherichia coli viability assay in an enclosed 3D microwell array chip, termed digital β-d-glucuronidase (GUS)-AST assay. It employs GUS, a specific metabolism-related enzyme, to convert the presence of E. coli into bright fluorescence. The random distribution of single bacteria in microwell array enables to quantify the E. coli concentrations by counting the positive microwells. We incorporate the most probable number with digital quantification to lower the limit of detection and expand the dynamic range to 7 orders. The digital GUS-AST assay is able to indicate the potency of antibiotics and determine the minimum inhibitory concentrations. A streamlined procedure of urine removal, bacterial separation, and digital GUS-AST is established to perform the direct analysis of bacteria population in urine. The sample-to-result workflow can be finished in 4.5 h with a limit of detection of 39 CFU/mL. With further development for additional pathogens and multiple antibiotic conditions, the digital GUS-AST assay could help physicians to prescribe timely targeted therapies for better patient outcomes and the minimum emergence of resistant bacteria.

Role of Efflux Pumps on Antimicrobial Resistance in Pseudomonas aeruginosa

Antimicrobial resistance is an old and silent pandemic. Resistant organisms emerge in parallel with new antibiotics, leading to a major global public health crisis over time. Antibiotic resistance may be due to different mechanisms and against different classes of drugs. These mechanisms are usually found in the same organism, giving rise to multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacteria. One resistance mechanism that is closely associated with the emergence of MDR and XDR bacteria is the efflux of drugs since the same pump can transport different classes of drugs. In Gram-negative bacteria, efflux pumps are present in two configurations: a transmembrane protein anchored in the inner membrane and a complex formed by three proteins. The tripartite complex has a transmembrane protein present in the inner membrane, a periplasmic protein, and a porin associated with the outer membrane. In Pseudomonas aeruginosa, one of the main pathogens associated with respiratory tract infections, four main sets of efflux pumps have been associated with antibiotic resistance: MexAB-OprM, MexXY, MexCD-OprJ, and MexEF-OprN. In this review, the function, structure, and regulation of these efflux pumps in P. aeruginosa and their actions as resistance mechanisms are discussed. Finally, a brief discussion on the potential of efflux pumps in P. aeruginosa as a target for new drugs is presented.

Genome-resolved insight into the reservoir of antibiotic resistance genes in aquatic microbial community

Aquatic microbial communities are an important reservoir of antibiotic resistance genes (ARGs). However, distribution and diversity of different ARG categories in environmental microbes with different ecological strategies is not yet well studied. Despite the potential exposure of the southern part of the Caspian Sea to the release of antibiotics, little is known about its natural resistome profile. We used a combination of Hidden Markov model (HMM), homology alignment and a deep learning approach for comprehensive screening of the diversity and distribution of ARGs in the Caspian Sea metagenomes at genome resolution. Detected ARGs were classified into five antibiotic resistance categories including prevention of access to target (44%), modification/protection of targets (30%), direct modification of antibiotics (22%), stress resistance (3%), and metal resistance (1%). The 102 detected ARG containing metagenome-assembled genomes of the Caspian Sea were dominated by representatives of Acidimicrobiia, Gammaproteobacteria, and Actinobacteria classes. Comparative analysis revealed that the highly abundant, oligotrophic, and genome streamlined representatives of taxa Acidimicrobiia and Actinobacteria modify the antibiotic target via mutation to develop antibiotic resistance rather than carrying extra resistance genes. Our results help with understanding how the encoded resistance categories of each genome are aligned with its ecological strategies.

Effects of nisin on the expression of virulence genes of methicillin-resistant/sensitive Staphylococcus aureus

Background and Objectives

Few studies have considered potential benefits of probiotic bacteria and their derivatives on human and animal health. Nisin is an antimicrobial agent that is produced by lactobacilli and served as a preservative in foods. This study aims to investigate whether nisin suppresses or decreases the genes involved in the pathogenicity of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA).

Materials and Methods

MSSA and MRSA strains were cultured at the ¼, ½, and 1 × minimum inhibitory concentration (MIC) of nisin. Next, RNA extraction was performed at the mid-exponential stage of growth, and cDNA was synthesized. The expression of virulence factors was measured by qPCR, and the data were analyzed by the ΔΔCt formula.

Results

Depending on the incubation times and the Lactobacillus species, the MIC of nisin on MRSA and MSSA observed in 800 and 1600 mg/l, respectively. The qPCR assay showed the expression level of the sea, agrA, and spa genes decreased and the level of the sae gene increased at the sub-MIC of nisin, and no antagonism was observed. Concerning MRSA, the maximum downregulation rate was observed in the sea gene (up to 5.9 folds) while in MSSA, the maximum downregulation rate was noticed in the agrA gene (up to 10 folds).

Conclusion

Due to the high inhibitory effect of the sub-MIC of nisin on the expression of virulence factor genes in MRSA and MSSA, this compound could potentially reduce the virulence of S. aureus.

Synthesis and Theoretical Studies of Biologically Active Thieno Nucleus Incorporated Tri and Tetracyclic Nitrogen Containing Heterocyclics Scaffolds via Suzuki Cross-Coupling Reaction

A new series of thieno nucleus embellished trinuclear (19, 20) and tetranuclear (21-24) nitrogen heteroaryl have been synthesized by the Suzuki cross-coupling reaction using bis(triphenylphosphine)palladium(II) dichloride. All the synthesized compounds were characterized by IR, ¹ H-NMR, ¹³ CNMR and Mass spectral properties. In vitro antibacterial studies of the synthesized compound were conducted using broth microdilution assay employing Gram-positive and Gram-negative strains and half-maximal inhibitory concentration (IC₅₀ ) was determined. The result showed that compound 20 possess best antibacterial activity against S. aureus and E. coli with IC₅₀ values of 60 μg mL^-1 and 90 μg mL^-1 . Further to determine the mode of antibacterial action, compounds 20 and 21 were examined for in vitro bacterial dehydrogenase inhibitory assay. To understand the binding affinity of the synthesized compounds, the docking study was performed in the bacterial dehydrogenase enzyme by AutoDock Vina software and structure was confirmed by Discovery Studio Visualizer. All the synthesized compounds were docked in a good manner within the active sites of the bacterial dehydrogenase enzyme and exhibited good binding energies.

Medicinal Properties of Anchusa strigosa and Its Active Compounds

Anchusa strigosa is a widespread weed in Greece, Syria, Turkey, Lebanon, Israel, Jordan, and Iran. The purpose of this study was to identify the phytochemicals of Anchusa strigose and estimate the pro-wound healing (pro-WH) and antimicrobial activities of its active compounds. An identification of volatile compounds was performed by GC/MS analysis; HPLC, LC-ESI-MS, and MALDI-TOF-MS were also applied. Our results demonstrate that two specific combinations of compounds from A. strigosa extract significantly enhanced WH (p < 0.001). Several flavonoids of the plant extract, including quercetin 3-O-rutinoside, kaempferol, kaempferol 3-O-β-rhamnopyranosyl(1→6)-β-glucopyranoside, and kaempferol 3-O-α-rhamnopyranosyl(1→6)-β-galactopyranoside, were effective against drug-resistant microorganisms. In addition, all the above-mentioned compounds had antibiofilm activity against Escherichia coli and Salmonella enteritidis.

Non-prescribed antibiotic dispensing practices for symptoms of urinary tract infection in community pharmacies and accredited drug dispensing outlets in Tanzania: a simulated clients approach

BACKGROUND

Antibiotic dispensing without prescription is a major determinant of the emergence of Antimicrobial Resistance (AMR) which has impact on population health and cost of healthcare delivery. This study used simulated clients describing UTI like symptoms to explore compliance with regulation, variations in dispensing practices and drug recommendation, and quality of seller-client interaction on the basis of the gender of the client and the type of drug outlets in three regions in Tanzania.

METHOD

A total of 672 Accredited Drug Dispensing Outlets (ADDOs) and community pharmacies were visited by mystery clients (MCs). The study was conducted in three regions of Tanzania namely Kilimanjaro (180, 26.79%), Mbeya (169, 25.15%) and Mwanza (323, 48.07%) in March-May 2020. During data collection, information was captured using epicollect5 software before being analyzed using Stata version 13.

RESULTS

Overall, 89.43% (CI: 86.87-91.55%) of drug sellers recommended antibiotics to clients who described UTI like symptoms but held no prescription and 58.93% were willing to sell less than the minimum recommended course. Female clients were more likely than male to be asked if they were taking other medications (27.2% vs 9.8%), or had seen a doctor (27.8% vs 14.7%), and more likely to be advised to consult a doctor (21.6% vs 9.0%); pharmacies addressed these issues more often than ADDOs (17.7% vs 13.2, 23.9% vs 16.6%, 17.7 vs 10.9% respectively). Sellers recommended 32 different drugs to treat the same set of symptoms, only 7 appear in the Tanzanian Standard Treatment Guidelines as recommended for UTI and 30% were 2nd and 3rd line drugs. ADDO sellers recommended 31 drug types (including 2nd and 3rd line) but had permission to stock only 3 (1st line) drugs. The most commonly suggested antibiotics were Azithromycin (35.4%) and ciprofloxacin (20.5%). Azithromycin was suggested more often in pharmacies (40.8%) than in ADDOs (34.4%) and more often to male clients (36.0%) than female (33.1%).

CONCLUSION

These findings support the need for urgent action to ensure existing regulations are adhered to and to promote the continuing professional development of drug sellers at all outlet levels to ensure compliance with regulation, high quality service and better antibiotic stewardship.

Lichens: An update on their ethnopharmacological uses and potential as sources of drug leads

ETHNOPHARMACOLOGICAL RELEVANCE

Lichens, a unique symbiotic association between an alga/cyanobacterium and a fungus, produce secondary metabolites that are a promising source of novel drug leads. The beauty and importance of lichens have not been adequately explored despite their manifold biological activities such as anticancer, antimicrobial, antioxidant, anti-inflammatory, analgesic, antipyretic and antiparasitic.

AIM OF THE STUDY

The present review collates and discusses the available knowledge on secondary metabolites and biological activities of lichens (in vitro and in vivo).

MATERIALS AND METHODS

Using relevant keywords (lichens, secondary metabolites, bioactivity, pharmacological activities), five electronic databases, namely ScienceDirect, PubMed, Google Scholar, Scopus and Recent Literature on Lichens, were searched for past and current scientific contributions up until May 2022. Literature focusing broadly on the bioactivity of lichens including their secondary metabolites were identified and summarized.

RESULTS

A total of 50 review articles and 189 research articles were searched. Information related to antioxidant, antimicrobial, anti-inflammatory, anticancer and insecticidal activities of 90 lichen species (from 13 families) and 12 isolated metabolites are reported. Over 90% of the studies comprised in vitro investigations, such as bioassays evaluating radical scavenging properties, lipid peroxidation inhibition and reducing power, cytotoxicity and antimicrobial bioassays of lichen species and constituents. In vivo studies were scarce and available only in fish and rats. Most of the studies were done by research groups in Brazil, France, Serbia, India and Turkey. There were relatively few reports from Asia and Africa despite the ubiquitous nature of lichens and the high occurrence in these continents.

CONCLUSION

Secondary metabolites from lichens are worthy of further investigation in terms of their potential therapeutic applicability, including better understanding of their mechanism(s) of action. This would be of great importance in the search for novel drugs.