The continuing crisis in antibiotic resistance

Computational and experimental insights into pharmacological potential: Synthesis, in vitro evaluation, and molecular docking analysis of bioactive urea and thiourea derivatives

This study delves into the synthesis, in vitro assessment, and molecular docking analysis of bioactive urea and thiourea derivatives, which have garnered significant attention in pharmaceutical chemistry due to their versatile chemical reactivity and potential therapeutic applications One pot synthetic approach was utilized to develop a diverse class of these compounds. Subsequent biological assessments, including antimicrobial assays, demonstrated their pharmacological potential by inhibiting pathogenic microorganisms. Molecular docking analysis offered computational insights into the interactions between these compounds and specific biomolecules, shedding light on their potential mechanisms of action. Overall, this comprehensive exploration contributes to the discovery of innovative therapeutic agents, as these bioactive urea and thiourea derivatives hold promise for addressing pressing healthcare challenges.

Antibacterial Nanoplatelets via Crystallization-Driven Self-Assembly of Poly(l-lactide)-Based Block Copolymers

Membrane-active antimicrobial materials are promising substances to fight antimicrobial resistance. Herein, crystallization-driven self-assembly (CDSA) is employed for the preparation of nanoparticles with different morphologies, and their bioactivity is explored. Block copolymers (BCPs) featuring a crystallizable and antimicrobial block were synthesized using a combination of ring-opening and photoiniferter RAFT polymerizations. Subsequently formed nanostructures formed by CDSA could not be deprotected without degradation of the structures. CDSA of deprotected BCPs yielded 2D diamond-shaped nanoplatelets in MeOH, while spherical nanostructures were observed for assembly in water. Platelets exhibited improved antibacterial capabilities against two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) compared to their spherical counterparts. The absence of hemolytic activity leads to the excellent selectivity of platelets. A mechanism based on membrane permeabilization was confirmed via dye-leakage assays. This study emphasized the impact of the shape of nanostructures on their interaction with bacterial cells and how a controlled assembly can improve bioactivity.

Antibacterial p-terphenyl and α‑pyrone derivates isolated from the marine-derived actinomycete Nocardiopsis sp. HDN154086

Assisted by OSMAC strategy, one new p-terphenyl and two new α‑pyrone derivates, namely nocarterphenyl I (1) and nocardiopyrone D-E (2-3), were obtained and characterized from the marine sediment-derived actinomycete Nocardiopsis sp. HDN154086. The structures of these compounds were determined on the basis of MS, NMR spectroscopic data and single-crystal X-ray diffraction. Compound 1 with a rare 2,2'-bithiazole structure among natural products showed promising activity against five bacteria with MIC values ranging from 0.8 to 1.6 μM and 3 exhibited notable antibacterial activity against MRSA compared the positive control ciprofloxacin.

An outbreak of multi-drug-resistant Acinetobacter baumannii on a burns ICU and its control with multi-faceted containment measures

BACKGROUND

Patients in burns centres are at high risk of acquiring multi-drug-resistant organisms (MDROs) due to the reduced skin barrier and long hospital stay.

METHODS

This study reports the investigation and control of an outbreak of MDR Acinetobacter baumannii in a burns centre. The 27 patients hospitalized in the centre during the outbreak were screened regularly, and a total of 132 environmental samples were analysed to identify a potential source. Fourier-transform infra-red (FT-IR) spectroscopy and multi-locus sequence typing were applied to characterize the outbreak strain.

RESULTS

Between August and November 2022, the outbreak affected eight patients, with 11 infections and three potentially related fatal outcomes. An interdisciplinary and multi-professional outbreak team implemented a bundle strategy with repetitive admission stops, isolation precaution measures, patient screenings, enhanced cleaning and disinfection, and staff education. FT-IR spectroscopy suggested that the outbreak started from a patient who had been repatriated 1 month previously from a country with high prevalence of MDR A. baumannii. Environmental sampling did not identify a common source. Acquisition of the outbreak strain was associated with a higher percentage of body surface area with burn lesions ≥2a [per percent increase: odds ratio (OR) 1.05, 95% confidence interval (CI) 0.99-1.12; P=0.09], and inversely associated with a higher nurse-to-patient ratio (per 0.1 increase: OR 0.34, 95% CI 0.10-1.12; P=0.06).

CONCLUSIONS

Burn patients with a higher percentage of body surface area with burn lesions ≥2a are at high risk of colonization and infection due to MDROs, particularly during periods of high workload. A multi-faceted containment strategy can successfully control outbreaks due to MDR A. baumannii in a burns centre.

Prevalence, antibiotic resistance pattern for bacteriuria from patients with urinary tract infections

Background and Aims

Antibiotic resistance presents a significant global public health challenge, particularly for urinary tract infections (UTIs), and is notably severe in developing countries. Surveillance of the antimicrobial susceptibility patterns of UTI-causing bacteria is crucial for effective treatment selection. This study aimed to analyze these patterns in bacteria isolated from the urine samples of patients at Mughda Medical College Hospital, Dhaka, Bangladesh.

Methods

A retrospective study (January 2019 to December 2020) at Mugdha Medical College and Hospital, Dhaka, examined clinical and laboratory data from patients with positive urine cultures (≥105 CFU/mL). The study classified patients into four age groups: children (1-<18 years), young adults (18-<33 years), middle-aged adults (33-50 years), and old adults (>50 years). The standard Kirby-Bauer method was used to assess antibiotic sensitivity to 28 common antibiotics.

Results

Among 243 positive urine cultures in both community- and hospital-acquired UTIs, Escherichia coli was the most common uropathogen (65.84%), followed by Klebsiella spp. (12.34%), Enterococcus spp. (8.23%), and other types of bacteria.

Conclusion

Old adults are particularly vulnerable to UTIs, with E. coli being the predominant causative agent in the study region. The observed antimicrobial resistance patterns underscore the necessity of judicious antibiotic selection to effectively treat UTIs across different age groups.

A comprehensive computational study to explore promising natural bioactive compounds targeting glycosyltransferase MurG in Escherichia coli for potential drug development

Peptidoglycan is a carbohydrate with a cross-linked structure that protects the cytoplasmic membrane of bacterial cells from damage. The mechanism of peptidoglycan biosynthesis involves the main synthesizing enzyme glycosyltransferase MurG, which is known as a potential target for antibiotic therapy. Many MurG inhibitors have been recognized as MurG targets, but high toxicity and drug-resistant Escherichia coli strains remain the most important problems for further development. In addition, the discovery of selective MurG inhibitors has been limited to the synthesis of peptidoglycan-mimicking compounds. The present study employed drug discovery, such as virtual screening using molecular docking, drug likeness ADMET proprieties predictions, and molecular dynamics (MD) simulation, to identify potential natural products (NPs) for Escherichia coli. We conducted a screening of 30,926 NPs from the NPASS database. Subsequently, 20 of these compounds successfully passed the potency, pharmacokinetic, ADMET screening assays, and their validation was further confirmed through molecular docking. The best three hits and the standard were chosen for further MD simulations up to 400 ns and energy calculations to investigate the stability of the NPs-MurG complexes. The analyses of MD simulations and total binding energies suggested the higher stability of NPC272174. The potential compounds can be further explored in vivo and in vitro for promising novel antibacterial drug discovery.

A Pharmacodynamic Study of Aminoglycosides against Pathogenic E. coli through Monte Carlo Simulation

This research focuses on combating the increasing problem of antimicrobial resistance, especially in Escherichia coli (E. coli), by assessing the efficacy of aminoglycosides. The study specifically addresses the challenge of developing new therapeutic approaches by integrating experimental data with mathematical modeling to better understand the action of aminoglycosides. It involves testing various antibiotics like streptomycin (SMN), kanamycin (KMN), gentamicin (GMN), tobramycin (TMN), and amikacin (AKN) against the O157:H7 strain of E. coli. The study employs a pharmacodynamics (PD) model to analyze how different antibiotic concentrations affect bacterial growth, utilizing minimum inhibitory concentration (MIC) to gauge the effective bactericidal levels of the antibiotics. The study's approach involved transforming bacterial growth rates, as obtained from time-kill curve data, into logarithmic values. A model was then developed to correlate these log-transformed values with their respective responses. To generate additional data points, each value was systematically increased by an increment of 0.1. To simulate real-world variability and randomness in the data, a Gaussian scatter model, characterized by parameters like κ and EC50, was employed. The mathematical modeling was pivotal in uncovering the bactericidal properties of these antibiotics, indicating different PD MIC (zMIC) values for each (SMN: 1.22; KMN: 0.89; GMN: 0.21; TMN: 0.32; AKN: 0.13), which aligned with MIC values obtained through microdilution methods. This innovative blend of experimental and mathematical approaches in the study marks a significant advancement in formulating strategies to combat the growing threat of antimicrobial-resistant E. coli, offering a novel pathway to understand and tackle antimicrobial resistance more effectively.

Understanding Knowledge and Attitude of Farmers towards Antibiotic Use and Antimicrobial Resistance in Jhunjhunu District, Rajasthan India

The misuse of antibiotics in veterinary practices by farmers is harming livestock production and food safety and leading to the rise of antibiotic resistance (AMR). This can also transfer resistant bacteria from animals to humans, posing a serious public health threat. However, we have not paid enough attention to understanding how farmers behave in this regard. Our study aims to explore farmers' behaviors and identify the factors that influence their choices. To conduct this study, we used a questionnaire with 40 questions and surveyed 208 farmers in Jhunjhunu district, Rajasthan. We analyzed the data using SPSS. Here are the key findings: About 58.3% of the farmers have some awareness of antibiotics, and 49.5% are aware of antimicrobial resistance (AMR). Notably, as the level of education increases, so does awareness of antibiotics. Unfortunately, 63.9% of the farmers are not aware of the withdrawal time, and 64% have no idea about the presence of antibiotic residues during this period. Around 75% of farmers vaccinate their animals, but approximately 56.9% of individuals have never undergone an antibiotic sensitivity test (ABST) for milk. Around 48.6% of farmers are unaware of government testing centers. Several factors hinder farmers from implementing proper animal management practices, such as the high fees of veterinarians. When their animals become sick, their first choice is home remedies, followed by using old prescriptions. Additionally, 63.9% stop treatment once the animal looks better. A significant portion (83.8%) of farmers rely on local pharmacists for medicine. It has been determined that there is no significant correlation between education, experience, age, and the level of awareness concerning withdrawal periods, the existence of government antibiotic sensitivity test (ABST) centers, and entities responsible for sending samples for ABST. In our qualitative analysis, focus groups identified significant barriers to following best farm practices and spreading awareness about AMR. These findings suggest that addressing AMR in livestock requires a comprehensive approach. This should include targeted education and awareness programs for farmers, as well as improved access to veterinary services.

Evaluation of Surface Modified Live Biotherapeutic Products for Oral Delivery

Live biotherapeutic products (LBPs), including symbiotic and genetically engineered bacteria, are a promising class of emerging therapeutics that are widely investigated both preclinically and clinically for their oral delivery to the gastrointestinal (GI) tract. One emergent delivery strategy involves the direct functionalization of LBP surfaces through noncovalent or covalent modifications to control LBP interactions with the GI microenvironment, thereby improving their viability, attachment, or therapeutic effect. However, unlike other therapeutic modalities, LBPs are living organisms which present two unique challenges for surface modifications: (1) this approach can directly interfere with key LBP biological processes (e.g., colonization, metabolite secretion) and (2) modification can be variable due to the dynamic nature of LBP surfaces. Collectively, these factors remain uncharacterized as they relate to the oral delivery of LBPs. Herein, we leverage our previously reported surface modification platform, which enables LBP surface-presentation of targeting ligands, to broadly evaluate and characterize surface modifications on LBPs. Specifically, we evaluate how LBP growth affects the dilution of surface-presented targeting ligands and the subsequent loss of specific target attachment over time. Next, we describe key surface modification parameters (e.g., concentration, residence time) that can be optimized to facilitate LBP target attachment. We then characterize how bioconjugation influences the suitability of LBPs for oral delivery by evaluating their growth, viability, storage, toxicity against mammalian cells, and in vivo colonization. Broadly, we describe key parameters that influence the performance of surface modified LBPs and subsequently outline an experimental pipeline for characterizing and evaluating their suitability for oral delivery.

The applications of 3D printing in wound healing: the external delivery of stem cells and antibiosis

As the global number of chronic wound patients rises, the financial burden and social pressure on patients increase daily. Stem cells have emerged as promising tissue engineering seed cells due to their enriched sources, multidirectional differentiation ability, and high proliferation rate. However, delivering them in vitro for the treatment of skin injury is still challenging. In addition, bacteria from the wound site and the environment can significantly impact wound healing. In the last decade, 3D bioprinting has dramatically enriched cell delivery systems. The produced scaffolds by this technique can be precisely localized within cells and perform antibacterial actions. In this review, we summarized the 3D bioprinting-based external delivery of stem cells and their antibiosis to improve wound healing.

Nanoparticles for Antimicrobial Agents Delivery-An Up-to-Date Review

Infectious diseases constitute an increasing threat to public health and medical systems worldwide. Particularly, the emergence of multidrug-resistant pathogens has left the pharmaceutical arsenal unarmed to fight against such severe microbial infections. Thus, the context has called for a paradigm shift in managing bacterial, fungal, viral, and parasitic infections, leading to the collision of medicine with nanotechnology. As a result, renewed research interest has been noted in utilizing various nanoparticles as drug delivery vehicles, aiming to overcome the limitations of current treatment options. In more detail, numerous studies have loaded natural and synthetic antimicrobial agents into different inorganic, lipid, and polymeric-based nanomaterials and tested them against clinically relevant pathogens. In this respect, this paper reviews the most recently reported successfully fabricated nanoformulations that demonstrated a great potential against bacteria, fungi, viruses, and parasites of interest for human medicine.

Helicobacter Pylori-Induced Gastric Infections: From Pathogenesis to Novel Therapeutic Approaches Using Silver Nanoparticles

Helicobacter pylori is the first formally recognized bacterial carcinogen and the most important single digestive pathogen responsible for the induction of gastroduodenal diseases such as gastritis, peptic ulcer, and, finally, gastric neoplasia. The recently reported high rates of antimicrobial drug resistance hamper the current therapies of H. pylori, with therapeutic failure reaching up to 40% of patients. In this context, new treatment options and strategies are urgently needed, but the successful development of these new therapeutic tools is conditioned by the understanding of the high adaptability of H. pylori to the gastric acidic environment and the complex pathogenic mechanism. Due to several advantages, including good antibacterial efficiency, possible targeted delivery, and long tissular persistence, silver nanoparticles (AgNPs) offer the opportunity of exploring new strategies to improve the H. pylori therapy. A new paradigm in the therapy of H. pylori gastric infections using AgNPs has the potential to overcome the current medical limitations imposed by the H. pylori drug resistance, which is reported for most of the current organic antibiotics employed in the classical therapies. This manuscript provides an extensive overview of the pathology of H. pylori-induced gastritis, gastric cancer, and extradigestive diseases and highlights the possible benefits and limitations of employing AgNPs in the therapeutic strategies against H. pylori infections.

The production and biochemical characterization of α-carbonic anhydrase from Lactobacillus rhamnosus GG

Abstract

We report the production and biochemical characterization of an α-carbonic anhydrase (LrhCA) from gram-positive probiotic bacteria Lactobacillus rhamnosus GG. CAs form a family of metalloenzymes that catalyze hydration of CO₂/interconversion between CO₂ and water to bicarbonate ions and protons. They are divided into eight independent gene families (α, β, γ, δ, ζ, η, θ, and ι). Interestingly, many pathogens have been identified with only β- and/or γ-CAs, which can be targeted with CA-specific inhibitors (CAIs) acting as anti-pathogen drugs. Since it is important to study the potential off-target effects of CAIs for both the human body and its commensal bacteria, we took L. rhamnosus GG as our study subject. To date, only a single α-CA has been identified in L. rhamnosus GG, which was successfully produced and biochemically characterized. LrhCA showed moderate catalytic activity with the following kinetic parameters: k_cat of 9.86 × 10⁵ s⁻¹ and k_cat/K_M of 1.41 × 10⁷ s⁻¹ M⁻¹. Moderate inhibition was established with 11 of the 39 studied sulfonamides. The best inhibitors were 5-((4-aminophenyl)sulfonamido)-1,3,4-thiadiazole-2-sulfonamide, 4-(2-hydroxymethyl-4-nitrophenyl-sulfonamidoethyl)-benzenesulfonamide, and benzolamide with K_i values of 319 nM, 378 nM, and 387 nM, respectively. The other compounds showed weaker inhibitory effects. The K_i of acetazolamide, a classical CAI, was 733 nM. In vitro experiments with acetazolamide showed that it had no significant effect on cell growth in L. rhamnosus GG culture. Several sulfonamides, including acetazolamide, are in use as clinical drugs, making their inhibition data highly relevant to avoid any adverse off-target effects towards the human body and its probiotic organisms.

Key points

• The α-carbonic anhydrase from Lactobacillus rhamnosus GG (LrhCA) is 24.3 kDa.

• LrhCA has significant catalytic activity with a kcat of 9.9 × 105 s-1.

• Acetazolamide resulted in a marginal inhibitory effect on cell growth.

Effect of asymptomatic bacteriuria on readmissions and rate of urosepsis after ureterorenoscopy for urolithiasis

Objective:

This study aims to assess whether the rate of readmissions after ureterorenoscopy (URS) is dependent on results of urine microscopy, culture and sensitivity (MC&S) or nitrite dipstick test performed before the procedure.

Patients and Methods:

All patients attending for ureteroscopy for stone disease over 12 months were included and had urine dipstick performed immediately prior to the surgery with mid-stream urine (MSU) sample sent for culture. Asymptomatic bacteriuria (ABU) was not treated before ureteroscopy. All included patients received standard antibiotic prophylaxis. Readmissions within 30 days of the procedure were evaluated.

Results:

A total 120 ureteroscopies were included, of which 20% had ABU. Eight patients (6.67%) were readmitted due to all procedure-related complications; among them, five (4.17%) were readmitted with urinary tract infection (UTI). Readmission rates with UTIs were similar for patients with sterile urine and those who had untreated ABU. Of those patients who were readmitted with UTI, all had a negative nitrite result on preoperative urine dipstick specimens. Most patients (54.17%) who had ABU also had a negative urinary nitrite test.

Conclusions:

Screening and routine treatment of ABU before ureteroscopy for urolithiasis may be unnecessary provided patients have standard antibiotic prophylaxis. Moreover, urine nitrite testing before ureteroscopy may not be a useful screening test for ABU before ureteroscopy.

Level of evidence:

2

The economic challenges of new drug development

The COVID-19 pandemic has witnessed highly successful efforts to produce effective vaccines and treatments at an unprecedented pace. This perspective discusses factors that made this possible, from long-term investments in research infrastructure to major government interventions that absorbed much of the risk from research and development. We discuss key economic obstacles in the discovery of new drugs for infectious diseases, from novel antibiotics to diseases that primarily affect the poor. The world's collective experience of the pandemic may present an opportunity to reform traditional economic models of drug discovery to better address unmet needs. A tax-funded global institution could provide incentives for drug discovery based on their global health impact. International co-operation would be needed to agree and commit to adequate funding mechanisms, and the necessary political will would require strong public support. With the current heightened appreciation of the need for global health system resilience, there may be no better opportunity than now.

Disparity in socio-economic status explains the pattern of self-medication of antibiotics in India: understanding from game-theoretic perspective

The emergence of antimicrobial resistance has raised great concern for public health in many lower-income countries including India. Socio-economic determinants like poverty, health expenditure and awareness accelerate this emergence by influencing individuals' attitudes and healthcare practices such as self-medication. This self-medication practice is highly prevalent in many countries, where antibiotics are available without prescriptions. Thus, complex dynamics of drug- resistance driven by economy, human behaviour, and disease epidemiology poses a serious threat to the community, which has been less emphasized in prior studies. Here, we formulate a game-theoretic model of human choices in self-medication integrating economic growth and disease transmission processes. We show that this adaptive behaviour emerges spontaneously in the population through a self-reinforcing process and continual feedback from the economy, resulting in the emergence of resistance as externalities of human choice under resource constraints situations. We identify that the disparity between social-optimum and individual interest in self-medication is primarily driven by the effectiveness of treatment, health awareness and public health interventions. Frequent multiple-peaks of resistant strains are also observed when individuals imitate others more readily and self-medication is more likely. Our model exemplifies that timely public health intervention for financial risk protection, and antibiotic stewardship policies can improve the epidemiological situation and prevent economic collapse.

Pan-Resistome Characterization of Uropathogenic Escherichia coli and Klebsiella pneumoniae Strains Circulating in Uganda and Kenya, Isolated from 2017-2018

Urinary tract infection (UTI) develops after a pathogen adheres to the inner lining of the urinary tract. Cases of UTIs are predominantly caused by several Gram-negative bacteria and account for high morbidity in the clinical and community settings. Of greater concern are the strains carrying antimicrobial resistance (AMR)-conferring genes. The gravity of a UTI is also determined by a spectrum of other virulence factors. This study represents a pilot project to investigate the burden of AMR among uropathogens in East Africa. We examined bacterial samples isolated in 2017-2018 from in- and out-patients in Kenya (KY) and Uganda (UG) that presented with clinical symptoms of UTI. We reconstructed the evolutionary history of the strains, investigated their population structure, and performed comparative analysis their pangenome contents. We found 55 Escherichia coli and 19 Klebsiella pneumoniae strains confirmed uropathogenic following screening for the prevalence of UTI virulence genes including fimH, iutA, feoA/B/C, mrkD, and foc. We identified 18 different sequence types in E. coli population while all K. pneumoniae strains belong to ST11. The most prevalent E. coli sequence types were ST131 (26%), ST335/1193 (10%), and ST10 (6%). Diverse plasmid types were observed in both collections such as Incompatibility (IncF/IncH/IncQ1/IncX4) and Col groups. Pangenome analysis of each set revealed a total of 2862 and 3464 genes comprised the core genome of E. coli and K. pneumoniae population, respectively. Among these are acquired AMR determinants including fluoroquinolone resistance-conferring genes aac(3)-Ib-cr and other significant genes: aad, tet, sul1, sul2, and cat, which are associated with aminoglycoside, tetracycline, sulfonamide, and chloramphenicol resistance, respectively. Accessory genomes of both species collections were detected several β-lactamase genes, blaCTX-M, blaTEM and blaOXA, or blaNDM. Overall, 93% are multi-drug resistant in the E. coli collection while 100% of the K. pneumoniae strains contained genes that are associated with resistance to three or more antibiotic classes. Our findings illustrate the abundant acquired resistome and virulome repertoire in uropathogenic E. coli and K. pneumoniae, which are mainly disseminated via clonal and horizontal transfer, circulating in the East African region. We further demonstrate here that routine genomic surveillance is necessary for high-resolution bacterial epidemiology of these important AMR pathogens.

Aquatic concentration and risk assessment of pharmaceutically active compounds in the environment

Pharmaceutically active compounds are increasingly detected in raw and treated wastewater, surface water, and drinking water worldwide. These compounds can cause adverse effects to the ecosystem even at low concentrations and, to assess these impacts, toxicity tests are essential. However, the toxicity data are scarce for many PhACs, and when available, they are dispersed in the literature. The values of pharmaceuticals concentration in the environment and toxicity data are essential for measuring their environmental and human health risks. Thus this review verified the concentrations of pharmaceuticals in the aquatic environment and the toxicity related to them. The risk assessment was also carried out. Diclofenac, naproxen, erythromycin, roxithromycin, and 17β-estradiol presented a high environment risk and 17α-ethinylestradiol presented a high human health risk. This shows the potential of these pharmaceuticals to cause adverse effects to the ecosystem and humans and establishes the necessity of their removal through advanced technologies.

Repeated exposure of nosocomial pathogens to silver does not select for silver resistance but does impact ciprofloxacin susceptibility

The rise of antimicrobial resistant bacteria coupled with a void in antibiotic development marks Antimicrobial Resistance as one of the biggest current threats to modern medicine. Antimicrobial metals are being developed and used as alternative anti-infectives, however, the existence of known resistance mechanisms and limited data regarding bacterial responses to long-term metal exposure are barriers to widespread implementation. In this study, a panel of reference and clinical strains of major nosocomial pathogens were subjected to serial dosage cycles of silver and ciprofloxacin. Populations exposed to silver initially showed no change in sensitivity, however, increasingly susceptibility was observed after the 25th cycle. A control experiment with ciprofloxacin revealed a selection for resistance over time, with silver treated bacteria showing faster adaptation. Morphological analysis revealed filamentation in Gram negative species suggesting membrane perturbation, while sequencing of isolated strains identified mutations in numerous genes. These included those encoding for efflux systems, chemosensory systems, stress responses, biofilm formation and respiratory chain processes, although no consistent locus was identified that correlated with silver sensitivity. These results suggest that de novo silver resistance is hard to select in a range of nosocomial pathogens, although silver exposure may detrimentally impact sensitivity to antibiotics in the long term. STATEMENT OF SIGNIFICANCE: The adaptability of microbial life continuously calls for the development of novel antibiotic molecules, however, the cost and risk associated with their discovery have led to a drying up in the pipeline, causing antimicrobial resistance (AMR) to be a major threat to healthcare. From all available strategies, antimicrobial metals and, more specifically, silver showcase large bactericidal spectrum and limited toxic effect which coupled with a large range of processes available for their delivery made these materials as a clear candidate to tackle AMR. Previous reports have shown the ability of this metal to enact a synergistic effect with other antimicrobial therapies, nevertheless, the discovery of Ag resistance mechanisms since the early 70s and limited knowledge on the long term influence of silver on AMR poses a threat to their applicability. The present study provides quantitative data on the influence of silver based therapies on AMR development for a panel of reference and clinical strains of major nosocomial pathogens, revealing that prolonged silver exposure may detrimentally impact sensitivity to antibiotics.

Synergistic Antibacterial Activity of an Active Compound Derived from Sedum takesimense against Methicillin-Resistant Staphylococcus aureus and Its Clinical Isolates

There are a growing number of reports of hospital-acquired infections caused by pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). Many plant products are now being used as a natural means of exploring antimicrobial agents against different types of human pathogenic bacteria. In this research, we sought to isolate and identify an active molecule from Sedum takesimense that has possible antibacterial activity against various clinical isolates of MRSA. NMR analysis revealed that the structure of the HPLC-purified compound was 1,2,4,6-tetra-O-galloyl-glucose. The minimum inhibitory concentration (MIC) of different extract fractions against numerous pathogenic bacteria was determined, and the actively purified compound has potent antibacterial activity against multidrug-resistant pathogenic bacteria, i.e., MRSA and its clinical isolates. In addition, the combination of the active compound and β-lactam antibiotics (e.g., oxacillin) demonstrated synergistic action against MRSA, with a fractional inhibitory concentration (FIC) index of 0.281. The current research revealed an alternative approach to combating pathogenesis caused by multi-drug resistant bacteria using plant materials. Furthermore, using a combination approach in which the active plant-derived compound is combined with antibiotics has proved to be a successful way of destroying pathogens synergistically.

The Role of Biosynthesized Silver Nanoparticles in Antimicrobial Mechanisms

Nanotechnology is an area of science in which new materials are developed. The correlation between nanotechnology and microbiology is essential for the development of new drugs and vaccines. The main advantage of combining these areas is to associate the latest technology in order to obtain new ways for solving problems related to microorganisms. This review seeks to investigate nanoparticle formation's antimicrobial properties, primarily when connected to the green synthesis of silver nanoparticles. The development of new sustainable methods for nanoparticle production has been instrumental in designing alternative, non-toxic, energy-friendly, and environmentally friendly routes. In this sense, it is necessary to study silver nanoparticles' green synthesis concerning their antimicrobial properties. Antimicrobial silver nanoparticles' mechanisms demonstrate efficiency to gram-positive bacteria, gram-negative bacteria, fungi, viruses, and parasites. However, attention is needed with the emergence of resistance to these antimicrobials. This article seeks to relate the parameters of green silver- based nanosystems with the efficiency of antimicrobial activity.

Brief Overview of Approaches and Challenges in New Antibiotic Development: A Focus On Drug Repurposing

Drug repurposing, or identifying new uses for existing drugs, has emerged as an alternative to traditional drug discovery processes involving de novo synthesis. Drugs that are currently approved or under development for non-antibiotic indications may possess antibiotic properties, and therefore may have repurposing potential, either alone or in combination with an antibiotic. They might also serve as "antibiotic adjuvants" to enhance the activity of certain antibiotics.

Validation of Qualitative Broth Volatilization Checkerboard Method for Testing of Essential Oils: Dual-Column GC–FID/MS Analysis and In Vitro Combinatory Antimicrobial Effect of Origanum vulgare and Thymus vulgaris against Staphylococcus aureus in Liquid and Vapor Phases

Combinatory action of antimicrobial agents such as essential oils (EOs) show to be an effective strategy to overcome the problem with increasing antibiotic resistance of microorganisms, including Staphylococcus aureus. The objective of this study was to evaluate in vitro antimicrobial interactions between Origanum vulgare and Thymus vulgaris EOs against various S.aureus strains in both liquid and vapor phases using the broth volatilization checkerboard method. Fractional inhibitory concentrations (FICs) were determined for both liquid and vapor phases, and the composition of EOs was analyzed by gas chromatography-mass spectrometry using dual-column/dual-detector gas chromatograph. Results of oregano and thyme EOs combination showed additive effects against all S. aureus strains in both phases. In several cases, sums of FICs were lower than 0.6, which can be considered a strong additive interaction. The lowest FICs obtained were 0.53 in the liquid phase and 0.59 in the gaseous phase. Chemical analysis showed that both EOs were composed of many compounds, including carvacrol, thymol, γ-terpinene, and p-cymene. This is the first report on oregano and thyme EOs interactions against S. aureus in the vapor phase. It also confirms the accuracy of the broth volatilization checkerboard method for the evaluation of combinatory antimicrobial effects of EOs in the vapor phase.

Adherence to Guidelines for Assessment and Empiric Antibiotics Recommendations for Community-Acquired Pneumonia at Ambo University Referral Hospital: Prospective Observational Study

OBJECTIVE

The high incidence and substantial morbidity and mortality associated with community-acquired pneumonia necessitate an accurate assessment and appropriate management of patients. This observational prospective study aimed to evaluate the physicians' adherence to the Ethiopian Standard Treatment Guideline for assessment and an empiric antibiotic selection for Community-acquired pneumonia.

RESULTS

The study indicated that the pneumonia severity assessment tool, CURB-65 score, was never used. Of 141 patients referred to an admitting diagnosis of severe community-acquired pneumonia, only 50 were subsequently found to satisfy the guideline criteria, over-diagnosis of 41.9%. Large proportions of the participants (130, 60%) were prescribed antibiotics in the last three months. The most commonly prescribed single antibiotic was Ceftriaxone (47, 21.7%), while ceftriaxone plus azithromycin was the most common combination, 110 (50.7%). In general, the extent of non-adherence to the national guideline for the use of antibiotics was 36.4%. In conclusion, the use of CRB65 scores was uncommon in the study setting. Poor adherence to Ethiopian Standard Treatment Guideline regarding the decision of hospital admission (41.9%) and the antimicrobial selection (36.4%) was determined.

Conventional and emerging technologies for removal of antibiotics from wastewater

Antibiotics and pharmaceuticals related products are used to enhance public health and quality of life. The wastewater that is produced from pharmaceutical industries still contains noticeable amount of antibiotics, and this has remained one of the major environmental problems facing public health. The conventional wastewater remediation approach employed by the pharmaceutical industries for the antibiotics wastewater removal is unable to remove the antibiotics completely. Besides, municipal and livestock wastewater also contain unmetabolized antibiotics released by human and animal, respectively. The antibiotic found in wastewater leads to antibiotic resistance challenges, also emergence of superbugs. Currently, numerous technological approaches have been developed to remove antibiotics from the wastewater. Therefore, it was imperative to critically review the weakness and strength of these current advanced technological approaches in use. Besides, the conventional methods for removal of antibiotics such as Klavaroti et al., Homem and Santos also discussed. Although, membrane treatment is discovered as the ultimate choice of approach, to completely remove the antibiotics, while the filtered antibiotics are still retained on the membrane. This study found, hybrid processes to be the best solution antibiotics removal from wastewater. Nevertheless, real-time monitoring system is also recommended to ascertain that, wastewater is cleared of antibiotics.

Interaction of synthetic antimicrobial peptides of the Hylin a1 family with models of eukaryotic structures: Zwitterionic membranes and DNA

Antimicrobial peptides (AMPs) have been appointed as a possible alternative to traditional antibiotics in face of pathogens increasing resistance to conventional drugs. Hylin a1 (IFGAILPLALGALKNLIK), an AMP extracted from the skin secretion of a South American frog, Hypsiboas albopunctatus, was found to show a strong cytotoxicity against bacteria and fungus, but also a considerable hemolytic action. Considering the toxicity of the peptide in eukaryotic cells, this work focuses on investigating the effects of the interaction of the Hylin a1 analogues W⁶Hya1, D⁰W⁶Hya1 and K⁰W⁶Hya1 with models of eukaryotic structures, namely zwitterionic liposomes of dipalmitoyl phosphatidylcholine (DPPC) and calf-thymus DNA (CT DNA). Through intrinsic Trp fluorescence we determined that the peptide affinity for fluid DPPC bilayers follows the decreasing order: D⁰W⁶Hya1 (+2) > W⁶Hya1 (+3) » K⁰W⁶Hya1 (+4). Fluorescence data also indicate that the Trp residue in the more positively charged peptide, K⁰W⁶Hya1, is less deep in the bilayer than the residue in the other two peptides. This finding is supported by differential scanning calorimetry (DSC) data, which shows that both D⁰W⁶Hya1 and W⁶Hya1 disturb DPPC gel-fluid transition slightly more effectively than K⁰W⁶Hya1. DPPC DSC profiles are homogeneously disturbed by the three peptides, probably related to peptide-membrane diffusion. Surprisingly, the peptide that displays the lowest affinity for PC membranes and is located at the more superficial position in the bilayer, K⁰W⁶Hya1, is the most efficient in causing formation of pores on the membrane, as attested by carboxyfluorescein leakage assays. The three peptides were found to interact with CT DNA, with a deep penetration of the Trp residue into hydrophobic pockets of the double helix, as indicated by the significant blue shift on the Trp fluorescence, and the displacement of DNA-bound ethidium bromide by the peptides. The experiments of DNA electrophoresis confirm that Hylin peptides bind DNA in a concentration-dependent manner, inducing complete DNA retardation at the relative AMP/plasmid DNA weight ratio of ~17. These findings could help to better understand the AMPs toxic effects on eukaryotic cells, thus contributing to the design of healthier therapeutic agents.

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AMP Hylin a1 analogues bind to both a model of eukaryotic membrane and DNA.

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The most cationic peptide has lowest affinity to PC vesicle and shallower binding.

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Peptide lower bilayer affinity is related to greater vesicle disruption and leakage.

•AMP hylin a1 analogues deep penetrate into hydrophobic pockets of CT-DNA double helix.

The Synergistic Effect of Mud Crab Antimicrobial Peptides Sphistin and Sph12-38 With Antibiotics Azithromycin and Rifampicin Enhances Bactericidal Activity Against Pseudomonas Aeruginosa

Overuse or abuse of antibiotics has undoubtedly accelerated the increasing prevalence of global antibiotic resistance crisis, and thus, people have been trying to explore approaches to decrease dosage of antibiotics or find new antibacterial agents for many years. Antimicrobial peptides (AMPs) are the ideal candidates that could kill pathogens and multidrug-resistant bacteria either alone or in combination with conventional antibiotics. In the study, the antimicrobial efficacy of mud crab Scylla paramamosain AMPs Sphistin and Sph₁₂₋₃₈ in combination with eight selected antibiotics was evaluated using a clinical pathogen, Pseudomonas aeruginosa. It was interesting to note that the in vitro combination of rifampicin and azithromycin with Sphistin and Sph₁₂₋₃₈ showed significant synergistic activity against P. aeruginosa. Moreover, an in vivo study was carried out using a mouse model challenged with P. aeruginosa, and the result showed that the combination of Sph₁₂₋₃₈ with either rifampicin or azithromycin could significantly promote the healing of wounds and had the healing time shortened to 4–5 days compared with 7–8 days in control. The underlying mechanism might be due to the binding of Sphistin and Sph₁₂₋₃₈ with P. aeruginosa lipopolysaccharides (LPS) and subsequent promotion of the intracellular uptake of rifampicin and azithromycin. Taken together, the significant synergistic antibacterial effect on P. aeruginosa in vitro and in vivo conferred by the combination of low dose of Sphistin and Sph₁₂₋₃₈ with low dose of rifampicin and azithromycin would be beneficial for the control of antibiotic resistance and effective treatment of P. aeruginosa-infected diseases in the future.

Antibiotic resistance genes (ARGs) and their associated environmental factors in the Yangtze Estuary, China: From inlet to outlet

The occurrence of antibiotic resistance genes (ARGs) and their associated environmental factors in estuaries are poorly understood. In this study, we comprehensively analyzed ARGs in both water and sediments from inlet to outlet of the Yangtze Estuary, China. The relative abundances of ARGs were higher in the turbidity maximum zone (TMZ) than other sites, implying that suspended particulate matter (SPM) was the major reservoir for ARGs in water. ARGs showed an increasing trend from inlet to outlet in sediments. Positively correlation between intI1 and sul1 in both water and sediments indicated that sul1 may be regulated by intI1. Correlation analysis and redundancy analysis showed that the spatial variations of estuarine ARGs were positively correlated with sample properties (e.g., temperature, SPM, pH) and chemical pollutants (e.g., heavy metals and antibiotic residues), among which chemical pollutants were the major drivers for the ARG distribution in both water and sediments.

In vitro antimicrobial combinatory effect of Cinnamomum cassia essential oil with 8-hydroxyquinoline against Staphylococcus aureus in liquid and vapour phase

AIMS

The objective of the study was to evaluate the antimicrobial interactions between two volatile agents, Cinnamomum cassia essential oil (CCEO) and 8-hydroxyquinoline (8-HQ) against Staphylococcus aureus strains in liquid and vapour phases.

METHODS AND RESULTS

In vitro antimicrobial effect of CCEO in combination with 8-HQ was evaluated against 12 strains of S. aureus by broth volatilization chequerboard method. Results show additive effects against all S. aureus strains for both phases. In several cases, sums of fractional inhibitory concentration values of our test combinations were lower than 0·6, which can be considered as a strong additive interaction. Moreover, composition of CCEO was analysed by gas chromatography-mass spectrometry analysis. In the CCEO, 26 compounds in total were identified, where (E)-cinnamaldehyde was the predominant compound, followed by cinnamyl acetate, α-copaene, bornyl acetate and caryophyllene.

CONCLUSIONS

Results showed additive in vitro growth-inhibitory effect of CCEO and 8-HQ combination against various standard strains and clinical isolates of S. aureus.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on antibacterial effect of 8-HQ and CCEO combination in liquid and vapour phases. Results of the study suggest these agents as potential candidates for development of new anti-staphylococcal applications that can be used in the inhalation therapy against respiratory infections.

Investigation of plasmid-mediated resistance in E. coli isolated from healthy and diarrheic sheep and goats

Escherichia coli is zoonotic bacteria and the emergence of antimicrobial-resistant strains becomes a critical issue in both human and animal health globally. This study was therefore aimed to investigate the plasmid-mediated resistance in E. coli strains isolated from healthy and diarrheic sheep and goats. A total of 234 fecal samples were obtained from 157 sheep (99 healthy and 58 diarrheic) and 77 goats (32 healthy and 45 diarrheic) for the isolation and identification of E. coli. Plasmid DNA was extracted using the alkaline lysis method. Phenotypic antibiotic susceptibility profiles were determined against the three classes of antimicrobials, which resistance is mediated by plasmids (Cephalosporins, Fluoroquinolone, and Aminoglycosides) using the disc-diffusion method. The frequency of plasmid-mediated resistance genes was investigated by PCR. A total of 159 E. coli strains harbored plasmids. The isolates antibiogram showed different patterns of resistance in both healthy and diarrheic animals. A total of (82; 51.5%) E. coli strains were multidrug-resistant. rmtB gene was detected in all Aminoglycoside-resistant E. coli, and the ESBL-producing E. coli possessed different CTX-M genes. Similarly, fluoroquinolone-resistant E. coli possessed different qnr genes. On the analysis of the gyrB gene sequence of fluoroquinolone-resistant E. coli, multiple point mutations were revealed. In conclusion, a high prevalence of E. coli with high resistance patterns to antimicrobials was revealed in the current study, in addition to a wide distribution of their resistance determinants. These findings highlight the importance of sheep and goats as reservoirs for the dissemination of MDR E. coli and resistance gene horizontal transfer.

Antimicrobial Stewardship Programs Are Required in a Department of Surgery: "How" Is the Question A Quasi-Experimental Study: Results after Three Years

Objective: Our aim was to describe our antimicrobial stewardship program and the methodology based on the results in a surgical department. Methods: Our study was a quasi-experimental study conducted from January 1, 2009, through September 30, 2017. The site was the General and Digestive Surgery Department in a public primary referral center, the University Hospital of Getafe (Madrid, Spain). We implemented the antimicrobial stewardship program following a prospective audit and feedback model, with a surgeon incorporated into the manaagement group. We studied the deaths and 30-day re-admission rates, length of stay, prevalence of gram-negative bacilli, meropenem resistance, and days of treatment with meropenem. Results: After three years of the program, we recorded a significant decrease in Pseudomonas aeruginosa prevalence, a significant increase in Klebsiella pneumoniae prevalence, a decrease in meropenem resistance, and a reduction in meropenem days of treatment. Conclusions: Antimicrobial stewardship programs have a desirable effect on patients. In our experience, the program team should be led by a staff from the particular department. When human resources are limited, the sustainability, efficiency, and effectiveness of interventions are feasible only with adequate computer support. Finally, but no less important, the necessary feedback between the prescribers and the team must be based on an ad hoc method such as that provided by statistical control charts, a median chart in our study.

Zinc and Copper Reduce Conjugative Transfer of Resistance Plasmids from Extended-Spectrum Beta-Lactamase-Producing Escherichia coli

The present work addresses the effect of excess levels of ZnCl₂ and CuSO₄ in the growth medium on the conjugative transfer of plasmids carrying the antibiotic resistance gene bla_CMY-2 from extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. Norwegian poultry are not treated prophylactically with antibiotics, but still, ESBL-producing E. coli are found in the chicken populations. Chickens receive higher amounts of Zn and Cu than their biological need, and several metals have been shown to act as drivers of antimicrobial resistance. In the present study, ESBL-producing E. coli strains collected from retail chicken meat were mated in broth containing various concentrations of ZnCl₂ and CuSO₄. Manual counting of transconjugants showed that ZnCl₂ and CuSO₄ reduced the conjugation frequency between E. coli strains in a concentration-dependent manner. Quantitative real-time PCR analyses showed that the presence of ZnCl₂ and CuSO₄ in the growth media reduced expression of the conjugation genes traB and nikB. By propagating monocultures over several generations, it was found that the bla_CMY-2 plasmids remained stable in the recipient strains. Together the results show that exposure of ESBL-producing E. coli to Zn and Cu reduce horizontal transfer of the bla_CMY-2 resistance plasmid by reducing expression of genes involved in conjugation in the plasmid donor strain.

Optimum positioning of wastewater treatment plants in a river network: A model-based approach to minimize microbial pollution

Microbial pollution in river networks is widespread, threatening human health and activities. Wastewater treatment plants are a major source of microbial pollution that affects downstream communities. We propose a simple modeling approach to identify possible hot-spots of microbial pollution in river networks receiving treated wastewater. We consider every reach in a river network as a potential site for the disposal of treated wastewater and we identify the corresponding section of the downstream river where the concentration of indicator bacteria exceeds a prescribed threshold value. In this paper, we introduce the methodology and demonstrate its application to a small river basin (Lockwitzbach, Germany). We computed the lengths of the polluted river sections for different scenarios in order to separately identify the impacts of hydrological boundary conditions and bacterial retention processes. Effective parameters describing bacterial retention were inferred from field samples. The proposed modeling approach can be used to generate dynamic maps of safe and vulnerable zones in a river network. Our approach helps disentangle the effects of network structure, hydrological variability and in-stream processes on the location and length of unsafe river sections. Our model can be used to identify optimal sites for the discharge of treated wastewater. For example, in the Lockwitzbach basin, we show that relocating the existing effluent discharge could reduce the stream length affected by severe microbial pollution by almost 30%.

Quantifying the impact of treatment history on plasmid-mediated resistance evolution in human gut microbiota

To understand how antibiotic use affects the risk of a resistant infection, we present a computational model of the population dynamics of gut microbiota including antibiotic resistance-conferring plasmids. We then describe how this model is parameterized based on published microbiota data. Finally, we investigate how treatment history affects the prevalence of resistance among opportunistic enterobacterial pathogens. We simulate treatment histories and identify which properties of prior antibiotic exposure are most influential in determining the prevalence of resistance. We find that resistance prevalence can be predicted by 3 properties, namely the total days of drug exposure, the duration of the drug-free period after last treatment, and the center of mass of the treatment pattern. Overall this work provides a framework for capturing the role of the microbiome in the selection of antibiotic resistance and highlights the role of treatment history for the prevalence of resistance.

Combinations of Antimicrobial Polymers with Nanomaterials and Bioactives to Improve Biocidal Therapies

The rise of antibiotic-resistant microorganisms has become a critical issue in recent years and has promoted substantial research efforts directed to the development of more effective antimicrobial therapies utilizing different bactericidal mechanisms to neutralize infectious diseases. Modern approaches employ at least two mixed bioactive agents to enhance bactericidal effects. However, the combinations of drugs may not always show a synergistic effect, and further, could also produce adverse effects or stimulate negative outcomes. Therefore, investigations providing insights into the effective utilization of combinations of biocidal agents are of great interest. Sometimes, combination therapy is needed to avoid resistance development in difficult-to-treat infections or biofilm-associated infections treated with common biocides. Thus, this contribution reviews the literature reports discussing the usage of antimicrobial polymers along with nanomaterials or other inhibitors for the development of more potent biocidal therapies.

Modulation of T Regulatory and Dendritic Cell Phenotypes Following Ingestion of Bifidobacterium longum, AHCC® and Azithromycin in Healthy Individuals

The probiotic Bifidus BB536 (BB536), which contains Bifidobacterium longum, has been shown to have enhanced probiotic effects when given together with a standardized extract of cultured Lentinula edodes mycelia (AHCC^®, Amino Up Co. Ltd., Sapporo, Japan). BB536 and AHCC^® may modulate T cell and dendritic cell (DC) phenotypes, and cytokine profiles to favour anti-inflammatory responses following antibiotic ingestion. We tested the hypothesis that orally administered BB536 and/or AHCC^®, results in modulation of immune effector cells with polarisation towards anti-inflammatory responses following antibiotic usage. Forty healthy male volunteers divided into 4 equal groups were randomised to receive either placebo, BB536, AHCC^® or a combination for 12 days in a double-blind manner. After 7 days volunteers also received 250 mg azithromycin for 5 days. Cytokine profiles from purified CD3+ T cells stimulated with PDB-ionomycin were assessed. CD4+ CD25+ forkhead box P3 (Foxp3) expression and peripheral blood DC subsets were assessed prior to treatment and subsequently at 7 and 13 days. There was no difference in cytokine secretion from stimulated CD3+ T cells between treatment groups. Compared with baseline, Foxp3 expression (0.45 ± 0.1 vs. 1.3 ± 0.4; p = 0.002) and interferon-gamma/interleukin-4 (IFN-γ/IL-4) ratios were increased post-treatment in volunteers receiving BB536 (p = 0.031), although differences between groups were not significant. For volunteers receiving combination BB536 and AHCC^®, there was an increase in myeloid dendritic cells (mDC) compared with plasmacytoid DC (pDC) counts (80% vs. 61%; p = 0.006) at post treatment time points. mDC2 phenotypes were more prevalent, compared with baseline, following combination treatment (0.16% vs. 0.05%; p = 0.002). Oral intake of AHCC^® and BB536 may modulate T regulatory and DC phenotypes to favour anti-inflammatory responses following antibiotic usage.

Industrial wastewater treatment plant enriches antibiotic resistance genes and alters the structure of microbial communities

Antibiotic resistance is an emerging global health crisis, driven largely by overuse and misuse of antibiotics. However, there are examples in which the production of these antimicrobial agents has polluted the environment with active antibiotic residues, selecting for antibiotic resistant bacteria and the genes they carry. In this work, we have used shotgun metagenomics to investigate the taxonomic structure and resistance gene composition of sludge communities in a treatment plant in Croatia receiving wastewater from production of the macrolide antibiotic azithromycin. We found that the total abundance of antibiotic resistance genes was three times higher in sludge from the treatment plant receiving wastewater from pharmaceutical production than in municipal sludge from a sewage treatment plant in Zagreb. Surprisingly, macrolide resistance genes did not have higher abundances in the industrial sludge, but genes associated with mobile genetic elements such as integrons had. We conclude that at high concentrations of antibiotics, selection may favor taxonomic shifts towards intrinsically resistant species or strains harboring chromosomal resistance mutations rather than acquisition of mobile resistance determinants. Our results underscore the need for regulatory action also within Europe to avoid release of antibiotics into the environment.

The Cytotoxic Properties of Some Tricyclic 1,3-Dithiolium Flavonoids

BACKGROUND

Due to the emergence of multidrug resistant microorganisms, new classes of antibiotics are needed. In this paper, we present the cytotoxic effects of five tricyclic flavonoids, one of which was previously identified as a potent antimicrobial agent.

METHODS

All five derivatives were tested against human HOS and MCF7 cancer cell lines using a wound scratch assay. The cytotoxic properties of previously reported flavonoid 4a were also evaluated using the standard MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) and live/dead assays, using NHDF, HOS and MCF7 cell lines.

RESULTS

All five derivatives were found to inhibit to some degree the proliferation of cancer cells. 4a was also found to be less toxic towards regular versus cancerous human cells. Moreover, the minimum bactericidal concentration of 4a against Staphylococcus aureus was found to be non-toxic for any of the tested human cell lines.

CONCLUSIONS

Derivative 4a has the potential of being used as a therapeutic agent against certain microorganisms. Further structure optimization is required for use against tumors.

Antibiotic Susceptibility Pattern of Enterobacteriaceae Isolated from Raw Meat and Ghanaian Coin Currencies at Cape Coast Metropolis, Ghana: The Public Health Implication

Introduction:

The emergence and upsurge of Multiple Antibiotic Resistant (MDR) Enterobacteriaceae in the environment is a cause of concern as this can result in an outbreak and spread to healthcare settings. MDR Enterobacteriaceae have been associated with high morbidity and mortality due to delay in selecting and delivering active therapy in time.

Aims & Objectives:

The study was conducted to investigate the level of contamination of raw meat and Ghanaian coins in circulation at Cape Coast Metropolis. In all, 10 raw meat were sampled each from chevron and beef from Kotokuraba market, and 400 Ghanaian coin currencies retrieved from food vendors, students, transport operators and banks were used in this study.

Materials & Methods:

The Enterobacteriaceae species isolated were tested for their susceptibility to Ampicillin, Tetracycline (TET), Gentamicin (GEN), Cotrimoxazole (COT), Cefuroxime (CRX), Cefixime (CXM), Cefotaxime (CTX), Penicillin (PEN), Cloxacillin (CXC), Erythromycin (ERY) and Amikacin (AMK) antibiotics using Mueller-Hinton agar antibiotic diffusion technique. Of the isolated Enterobacteriaceae, 30% and 62% from chevron and beef respectively and 14.17%, 13.75% and 10.63% from food vendors, students and transport operators respectively showed resistance to some of the antibiotics tested.

Results & Discussion:

8.6% of the Escherichia coli (E. coli) isolated from chevon were resistant to CRXr-CHLr-AMPr-COTr-GEMr and 15.5% of CRXi-CHLi-AMPr-TETr-COTr from beef. 40.0% of E. coli isolated from coin currencies were resistant to CRXr-CHLr-AMPr-TETr-CTXr, 50.0% of Enterobacter spp to CRXr-CHLr-AMPr-TETr-CTXr, 16.67% of Proteus spp to CRXi-CHLi-AMPr-TETr-AMKi, 40% Pseudomonas spp to CRXr-AMPr-TETr-AMKi and 100% of Enterobacter spp to CRXr-AMPr-TETi-CTXr.

Conclusion:

The multidrug-resistant Enterobacteriaceae isolates from circulating Ghanaian coins and raw meats in the Cape Coast metropolis is an indication of an impending danger which requires immediate attention to prevent a possible outbreak and spread from the society to the hospital setting.

The highly efficient elimination of intracellular bacteria via a metal organic framework (MOF)-based three-in-one delivery system

Numerous infectious diseases that cause clinical failures and relapses after antibiotic therapy have been confirmed to be induced by pathogenic intracellular bacteria. The existing therapeutic strategies fail to eliminate intracellular bacteria mainly due to a guard reservoir provided by the cell membrane, which can deactivate antibiotics. Herein, we have reported the design of a pH-responsive metal organic framework (MOF)/antibiotic synergistic system for the targeted highly efficient elimination of intracellular bacteria. The obtained tetracycline (Tet)@ZIF-8@ hyaluronic acid (HA) system (abbreviated to TZH) can be taken up by cells owing to the presence of CD44 receptors on the cell surface via an HA-mediated pathway. Zinc ions and antibiotics, released from TZH under acidic conditions caused by bacteria, have a synergistic antibacterial effect both in vitro and in vivo. The clearance rate of TZH to the intracellular bacteria reached over 98% within the limits of biotoxicity, which indicated that this delivery system can pass the cell membrane "barriers" and restore the efficacy of endangered antibiotics. This synergistic strategy shows potential in optimizing the efficacy-dosage correlation of antibiotics for related infection treatments and constructing versatile controlled release delivery systems for a broad range of applications.

Land Use Influences Antibiotic Resistance in the Microbiome of Soil Collembolans Orchesellides sinensis

Numerous studies have investigated the composition and diversity of antibiotic resistance genes (ARGs) in multiple environments but the pattern of ARGs in field-collected soil fauna remains poorly understood. In the present study soil collembolans were collected from six sites with three different land use types (parkway land, park land, and arable land) and 285 ARGs and 10 mobile genetic elements (MGEs) in the microbiome of these "wild" collembolans were quantified by high-throughput quantitative PCR. A total of 76 unique ARGs and 5 MGEs were detected. There were significant differences between collection sites in the antibiotic resistome in the collembolans. Land use significantly altered the distribution patterns of collembolan ARGs. Thirty shared ARGs and three shared MGEs were identified. The co-occurrences of shared resistomes were largely random, and more positive relationships were found in the coassociation network. Partial redundancy analysis confirms that the changes in bacterial communities explained 27.77% of the variation in ARGs. These findings suggest that resistance genes are pervasive in the microbiome associated with the field collembolan and the activity of the collembolans may contribute to the spread and dissemination of resistance genes in the environment, an aspect of ARGs that has until now been largely overlooked.

Vaccination with the Staphylococcus aureus secreted proteins EapH1 and EapH2 impacts both S. aureus carriage and invasive disease

INTRODUCTION

There is a need for an efficacious vaccine reducing infections due to Staphylococcus aureus, a common cause of community and hospital infection. Infecting organisms originate from S. aureus populations colonising the nares and bowel. Antimicrobials are widely used to transiently reduce S. aureus colonisation prior to surgery, a practice which is selecting for resistant S. aureus isolates. S. aureus secretes multiple proteins, including the protease inhibitors extracellular adhesion protein homologue 1 and 2 (EapH1 and EapH2).

METHODS

Mice were vaccinated intramuscularly or intranasally with Adenovirus serotype 5 and Modified Vaccinia Ankara viral vectors expressing EapH1 and EapH2 proteins, or with control viruses. Using murine S. aureus colonisation models, we monitored S. aureus colonisation by sequential stool sampling. Monitoring of S. aureus invasive disease after intravenous challenge was performed using bacterial load and abscess numbers in the kidney.

RESULTS

Intramuscular vaccination with Adenovirus serotype 5 and Modified Vaccinia Ankara viral vectors expressing EapH1 and EapH2 proteins significantly reduces bacterial recovery in the murine renal abscess model of infection, but the magnitude of the effect is small. A single intranasal vaccination with an adenoviral vaccine expressing these proteins reduced S. aureus gastrointestinal (GI) tract colonisation.

CONCLUSION

Vaccination against EapH1 / EapH2 proteins may offer an antibiotic independent way to reduce S. aureus colonisation, as well as contributing to protection against S. aureus invasive disease.

Rapidly discriminating culture-negative urine specimens from patients with suspected urinary tract infections by UF-5000

Aim: A rapid and reliable method of discriminating such specimens would be very useful. Materials & methods: We analyzed 566 urine specimens from patients with suspected urinary tract infections using a fully automated urine particle analyzer (UF-5000) and evaluated its performance for culture-negative urine specimens. Results: Using the algorithm cutoff values of bacteria less than 30/μl and/or white blood cell less than 200/μl, we obtained a sensitivity of 97.8%, a specificity of 74.6%, a positive predictive value of 46.9%, a negative predictive value of 99.3%, an agreement of 78.9% with the culture method and reduced 61% unnecessary urine culture. Regarding the discrimination of bacterial Gram groups, 67.7% (63/93) of cases were correctly analyzed using the UF-5000 bacteria information, with a Cohen's kappa concordance coefficient of 0.775 (χ2 = 31.65, p < 0.001). Conclusion: The performance of UF-5000 for rapidly discriminating culture-negative specimens was quite acceptable for clinical use.

Role of increasing leukocyturia for detecting the transition from asymptomatic bacteriuria to symptomatic infection in women with recurrent urinary tract infections: A new tool for improving antibiotic stewardship

OBJECTIVES

To evaluate the importance of leukocyturia in detecting the transition from asymptomatic bacteriuria to symptomatic infection in women with recurrent urinary tract infections.

METHODS

In this cross-sectional study, we evaluated all women with recurrent urinary tract infection and asymptomatic bacteriuria who had been enrolled in two previous studies. Data from urological visits, urine analyses and microbiological evaluations were collected. Patients were divided into two groups: patients with symptomatic recurrence (group A) and patients without recurrence (group B), with a mean follow-up period of 38.8 months. Data on leukocyturia and clinical data were compared. Logistic regression analyses were carried out and areas under the receiver operating characteristic curves were calculated.

RESULTS

A total of 301 women with symptomatic urinary tract infection were included in group A, whereas 249 women without clinical infection were included in group B. Group A showed a higher level of leukocytes in the urinary analysis taken at the moment of recurrence when compared with the baseline value (mean leukocytes per high power field 54 ± 5 vs 19 ± 6 at baseline; P < 0.0001). When an increase of leukocytes/mm3 of >150% from baseline was used for logistic regression, the area under the receiver operating characteristic of the model was 0.82 (95% CI 0.78-0.94; P = 0.01). An increase of leukocytes/mm3 of >150% from baseline had a sensitivity of 90.1% and a specificity of 91.2% for symptomatic urinary tract infection.

CONCLUSIONS

This study shows that an increase of leukocyturia of >150% from baseline has a predictive role for the transition from asymptomatic bacteriuria to symptomatic urinary tract infection in women with recurrent urinary tract infections.