Bacterial Drug Resistance Research Articles

Molecular Targets for Antibody-Based Anti-Biofilm Therapy in Infective Endocarditis.

Infective endocarditis (IE) is a heart disease caused by the infection of heart valves, majorly caused by Staphilococcus aureus. IE is initiated by bacteria entering the blood circulation in favouring conditions (e.g., during invasive procedures). So far, the conventional antimicrobial strategies based on the usage of antibiotics remain the major intervention for treating IE. Nevertheless, the therapeutic efficacy of antibiotics in IE is limited not only by the bacterial drug resistance, but also by the formation of biofilms, which resist the penetration of antibiotics into bacterial cells. To overcome these drawbacks, the development of anti-biofilm treatments that can expose bacteria and make them more susceptible to the action of antibiotics, therefore resulting in reduced antimicrobial resistance, is urgently required. A series of anti-biofilm strategies have been developed, and this review will focus in particular on the development of anti-biofilm antibodies. Based on the results previously reported in the literature, several potential anti-biofilm targets are discussed, such as bacterial adhesins, biofilm matrix and bacterial toxins, covering their antigenic properties (with the identification of potential promising epitopes), functional mechanisms, as well as the antibodies already developed against these targets and, where feasible, their clinical translation.

Carbon dots derived from folic acid as an ultra-succinct smart antimicrobial nanosystem for selective killing of S. aureus and biofilm eradication

Developing efficient and safe approach to counteract the bacterial infections has become an urgent clinical challenge. In this work, we report folic acid derived carbon dots (FA-CDs) prepared by a one-step pyrolysis method. The FA-CDs can respond to the environmental stimuli of bacterial infections and acquire antimicrobial capacity “on demand” as a simple and effective antimicrobial nanosystem. The assays on antibacterial properties and mechanism show that FA-CDs are able to induce the gradual increase of intracellular reactive oxygen species (ROS) levels in bacteria under the simulated acidic environment and display pH-responsive biocidal activity. In a neutral condition, FA-CDs have no antibacterial activity, which will be conducive to mitigating the rise of bacterial drug resistance. The responsive antibacterial behavior can be attributed to that FA-CDs exhibit distinctive oxidase-like and peroxidase-like activity under acidic stimuli and inhibit the superoxide dismutase activity in bacteria cells, causing the accumulation of intracellular ROS. Meanwhile, FA-CDs can selectively kill Gram-positive bacterium S. aureus and remove mature biofilms. Besides, the in vitro and in vivo experiments demonstrate that FA-CDs possess excellent biocompatibility, and show remarkable therapeutic effect on the S. aureus-infected back wound models of mouse, which are crucial for clinical applications. Thus, this study highlights the potential application of FA-CDs as an ultra-succinct smart antimicrobial nanosystem for coping with infections caused by S. aureus in the clinical setting, and will bring about a new perspective on developing antimicrobial CDs.

Fabrication of hierarchical 3D Ag/Bi2S3 nanoflowers for antibacterial application

Bacterial drug resistance caused by the abuse of antibiotics poses a serious threat to human health. Thus, the development of alternative strategies for the replacing of antibiotics is necessary. Herein, a hierarchical three-dimensional Bi2S3 (BS) nanoflowers were facile fabricated and employed as supporter for the growth of silver nanoparticles (Ag NPs). Combining the excellent antimicrobial activity of Ag NPs, the as-resulted Ag/BS exhibited broad-spectrum antibacterial activity against pathogenic bacteria. Investigation on antibacterial mechanism revealed the treatment of Ag/BS damages the bacterial cell membrane, leading to the loss of intracellular substances. The compromised membrane caused the reduction of membrane bound enzymes activity, resulting in the arrest of metabolic activity. Simultaneously, Ag/BS broke the bacterial antioxidant defense system by raising the intracellular ROS levels, caused the oxidative damage, resulting in the loss of bacterial viability. Moreover, the satisfactory biocompatibility and effective antibacterial performance of Ag/BS were confirmed by performing in vitro cytotoxicity and in vivo antibacterial assay. Accordingly, this work opens up possibility for the construction of Bi2S3 based multifunctional nanomaterials and its application for pathogenic bacteria control.

Nanoemulsion as an Effective Inhibitor of Biofilm-forming Bacterial Associated Drug Resistance: An Insight into COVID Based Nosocomial Infections.

Antibiotic overuse has resulted in the microevolution of drug-tolerant bacteria. Understandably it has become one of the most significant obstacles of the current century for scientists and researchers to overcome. Bacteria have a tendency to form biofilm as a survival mechanism. Biofilm producing microorganism become far more resistant to antimicrobial agents and their tolerance to drugs also increases. Prevention of biofilm development and curbing the virulency factors of these multi drug resistant or tolerant bacterial pathogens is a newly recognised tactic for overcoming the challenges associated with such bacterial infections and has become a niche to be addressed. In order to inhibit virulence and biofilm from planktonic bacteria such as, Pseudomonas aeruginosa, Acinetobacter baumannii, and others, stable nanoemulsions (NEs) of essential oils (EOs) and their bioactive compounds prove to be an interesting solution. These NEs demonstrated significantly greater anti-biofilm and anti-virulence activity than commercial antibiotics. The EO reduces disease-causing gene expression, which is required for pathogenicity, biofilm formation and attachment to the surfaces. Essential NE and NE-loaded hydrogel surface coatings demonstrates superior antibiofilm activity which can be employed in healthcare-related equipments like glass, plastic, and metal chairs, hospital beds, ventilators, catheters, and tools used in intensive care units. Thus, anti-virulence and anti-biofilm forming strategies based on NEs-loaded hydrogel may be used as coatings to combat biofilm-mediated infection on solid surfaces.

Antimicrobial mechanisms of traditional Chinese medicine and reversal of drug resistance: a narrative review.

In recent years, the extensive use of antibiotics worldwide has led to an increase in the number of drug-resistant bacterial strains, thus resulting in an increasingly severe degree of bacterial resistance. For thousands of years, traditional Chinese medicine (TCM) has provided natural and unique advantages in the treatment of infectious diseases. Therefore, it is important to develop further and use TCM to treat clinical infections caused by drug-resistant bacteria. A literature search was performed using PubMed, Web of Science, Google Scholar, and the China National Knowledge Infrastructure databases. The articles were analyzed to extract information on the antimicrobial effects of Chinese herbal medicines, compounded Chinese medicines, monomeric compounds of herbal origin, and the combined use of Chinese medicine and antimicrobial drugs and to determine the synergistic effect of the combination of Chinese medicine and antibiotics, as well as investigate the possibility of restoring the antibiotic sensitivity of drug-resistant strains. The mechanisms underlying the antibacterial properties of TCM involve altering membrane permeability, inhibiting protein and nucleic acid synthesis, inhibiting enzyme activity in vivo, and controlling the ability of pathogenic bacteria. In addition, the mechanism underlying TCM-induced reversal of bacterial drug resistance is discussed, particularly in terms of the elimination of resistant (R) plasmids and the inhibition of extended-spectrum β-lactamases, bacterial biofilm formation, and bacterial efflux pump activity. This paper reviewed the recent relevant literature on antimicrobial action and its mechanisms, as well as the mechanisms of drug resistance reversal by TCM to provide a reference for clinical drug use, prevention and control of bacterial infection, and research and development of new drugs.

The Application of the CRISPR-Cas System in Antibiotic Resistance.

The emergence and global epidemic of antimicrobial resistance (AMR) poses a serious threat to global public health in recent years. AMR genes are shared between bacterial pathogens mainly via horizontal gene transfer (HGT) on mobile genetic elements (MGEs), thereby accelerating the spread of antimicrobial resistance (AMR) and increasing the burden of drug resistance. There is an urgent need to develop new strategies to control bacterial infections and the spread of antimicrobial resistance. The clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas) are an RNA-guided adaptive immune system in prokaryotes that recognizes and defends against invasive genetic elements such as phages and plasmids. Because of its specifically target and cleave DNA sequences encoding antibiotic resistance genes, CRISPR/Cas system has been developed into a new gene-editing tool for the prevention and control of bacterial drug resistance. CRISPR-Cas plays a potentially important role in controlling horizontal gene transfer and limiting the spread of antibiotic resistance. In this review, we will introduce the structure and working mechanism of CRISPR-Cas systems, followed by delivery strategies, and then focus on the relationship between antimicrobial resistance and CRISPR-Cas. Moreover, the challenges and prospects of this research field are discussed, thereby providing a reference for the prevention and control of the spread of antibiotic resistance.

LuxR family transcriptional repressor YjjQ modulates the biofilm formation and motility of avian pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC) can cause the acute and sudden death of poultry, which leads to serious economic losses in the poultry industry. Biofilm formation contributes to the persistence of bacterial infection, drug resistance, and resistance to diverse environmental stress. Many transcription regulators in APEC play an essential role in the formation of biofilm and could provide further insights into APEC pathogenesis. YjjQ has an important role in the pathogenicity of bacteria by regulating the expression of virulence factors, such as flagellar and iron uptake. However, YjjQ regulates other virulence factors, and their role in the overall regulatory network is unclear. Here, we further evaluate the function of YjjQ on APEC biofilm formation and motility. In this study, we successfully constructed mutant (AE27∆yjjQ) and complement (AE27ΔyjjQ-comp) strains of the wild-type strain AE27. Inactivation of the yjjQ gene significantly increased biofilm-forming ability in APEC. Scanning electron microscopy showed that the biofilm formation of the AE27 was single-layered and flat, whereas that of the AE27∆yjjQ had a porous three-dimensional structure. Moreover, the deletion of the yjjQ gene inhibited the motility of APEC. RNA-sequencing was used to further investigate the regulatory mechanism of YjjQ in APEC. The results indicate that YjjQ regulates biofilm formation and flagellar genes in AE27∆yjjQ. RT-qPCR shows that YjjQ affects the transcriptional levels of genes, including flagella genes (flhD, flhC and flgE), and biofilm formation genes (pstA, uhpC, nikD, and ygcS). These results confirm that the transcription regulator YjjQ is involved in APEC biofilm formation and motility, and provide new evidence for the prevention and control of APEC.

Synergistic Antimicrobial Effect of Antimicrobial Peptides CATH-1, CATH-3, and PMAP-36 With Erythromycin Against Bacterial Pathogens.

With the increasing bacterial resistance to traditional antibiotics, there is an urgent need for the development of alternative drugs or adjuvants of antibiotics to enhance antibacterial efficiency. The combination of antimicrobial peptides (AMPs) and traditional antibiotics is a potential alternative to enhance antibacterial efficiency. In this study, we investigated the synergistic bactericidal effect of AMPs, including chicken (CATH-1,−2,−3, and -B1), mice (CRAMP), and porcine (PMAP-36 and PR-39) in combination with conventional antibiotics containing ampicillin, tetracycline, gentamicin, and erythromycin against Staphylococcus aureus, Salmonella enteritidis, and Escherichia coli. The results showed that the minimum bactericidal concentration (MBC) of CATH-1,−3 and PMAP-36 was lower than 10 μM, indicating that these three AMPs had good bacterial activity against S. aureus, S. enteritidis, and E. coli. Then, the synergistic antibacterial activity of AMPs and antibiotics combination was determined by the fractional bactericidal concentration index (FBCI). The results showed that the FBCI of AMPs (CATH-1,−3 and PMAP-36) and erythromycin was lower than 0.5 against bacterial pathogens, demonstrating that they had a synergistic bactericidal effect. Furthermore, the time-killing kinetics of AMPs (CATH-1,−3 and PMAP-36) in combination with erythromycin showed that they had a continuous killing effect on bacteria within 3 h. Notably, the combination showed lower hemolytic activity and cytotoxicity to mammal cells compared to erythromycin and peptide alone treatment. In addition, the antibacterial mechanism of CATH-1 and erythromycin combination against E. coli was studied. The results of the scanning electron microscope showed that CATH-1 enhanced the antibacterial activity of erythromycin by increasing the permeability of bacterial cell membrane. Moreover, the results of bacterial migration movement showed that the combination of CATH-1 and erythromycin significantly inhibits the migration of E. coli. Finally, drug resistance analysis was performed and the results showed that CATH-1 delayed the emergence of E. coli resistance to erythromycin. In conclusion, the combination of CATH-1 and erythromycin has synergistic antibacterial activity and reduces the emergence of bacterial drug resistance. Our study provides valuable information to develop AMPs as potential substitutes or adjuvants for traditional antibiotics.

Synthesis and biological evaluation of antibacterial activity of novel clarithromycin derivatives incorporating 1,2,3-triazole moieties at the 4″- and 11-OH positions

Bacterial infection is still one of the diseases that threaten human health, and bacterial drug resistance is widespread worldwide. As a result, their eradication now largely relies on antibacterial drug discovery. Here, we reveal a novel approach to the development of 14-membered macrolide antibiotics by describing the design, synthesis, and evaluation of novel clarithromycin derivatives incorporating 1,2,3-triazole moieties at the 4″- and 11-OH positions. Using chemical synthesis, 35 clarithromycin derivatives were prepared, and their antibacterial properties were profiled. We found that compounds 8e-8h, 8l-8o, 8v, and 19d were as potent as azithromycin against Enterococcus faecalis ATCC29212. Furthermore, compounds 8c, 8d, 8n, and 8o showed slightly improved antibacterial activity (2-fold) against Acinetobacter baumannii ATCC19606 when compared with azithromycin and clarithromycin. In addition, compounds 8e, 8f, 8h, 8l, and 8v exhibited excellent antibacterial activity against Staphylococcus aureus ATCC43300, Staphylococcus aureus PR, and Streptococcus pneumoniae ER-2. These compounds were generally 64- to 128-fold more active than azithromycin, and 32- to 128-fold more active than clarithromycin. The results of molecular docking indicated that compound 8f may bind to the nucleotide residue A752 through hydrogen-bonding, hydrophobic, electrostatic, or π-π stacking interactions. The predicted ClogP data suggested that higher values of ClogP (>6.65) enhanced the antibacterial activity of compounds such as 8e, 8f, 8h, 8l, and 8v. The determination of the minimum bactericidal concentration showed that most of the tested compounds were bacteriostatic agents. From this study of bactericidal kinetics, we can conclude that compound 8f had a concentration- and time-dependent effect on the proliferation of Staphylococcus aureus ATCC43300. Finally, the results of the cytotoxicity assay showed that compound 8f exhibited no toxicity at the effective antibacterial concentration.

Restoring and Enhancing the Potency of Existing Antibiotics against Drug-Resistant Gram-Negative Bacteria through the Development of Potent Small-Molecule Adjuvants.

The rapid and persistent emergence of drug-resistant bacteria poses a looming public health crisis. The possible task of developing new sets of antibiotics to replenish the existing ones is daunting to say the least. Searching for adjuvants that restore or even enhance the potency of existing antibiotics against drug-resistant strains of bacteria represents a practical and cost-effective approach. Herein, we describe the discovery of potent adjuvants that extend the antimicrobial spectrum of existing antibiotics and restore their effectiveness toward drug-resistant strains including mcr-1-expressing strains. From a library of cationic compounds, MD-100, which has a diamidine core structure, was identified as a potent antibiotic adjuvant against Gram-negative bacteria. Further optimization efforts including the synthesis of ∼20 compounds through medicinal chemistry work led to the discovery of a much more potent compound MD-124. MD-124 was shown to sensitize various Gram-negative bacterial species and strains, including multidrug resistant pathogens, toward existing antibiotics with diverse mechanisms of action. We further demonstrated the efficacy of MD-124 in an ex vivo skin infection model and in an in vivo murine systemic infection model using both wild-type and drug-resistant Escherichia coli strains. MD-124 functions through selective permeabilization of the outer membrane of Gram-negative bacteria. Importantly, bacteria exhibited low-resistance frequency toward MD-124. In-depth computational investigations of MD-124 binding to the bacterial outer membrane using equilibrium and steered molecular dynamics simulations revealed key structural features for favorable interactions. The very potent nature of such adjuvants distinguishes them as very useful leads for future drug development in combating bacterial drug resistance.

Analysis of Factors Related to Neonatal Infection and Monitoring of Bacterial Drug Resistance.

To study the factors related to neonatal infection, as well as bacterial distribution and drug resistance in neonatal infections, in an obstetrics and gynecology hospital in Shanghai. The bacterial culture and drug resistance monitoring results from neonates treated at the hospital from January 2020 to June 2021 were analyzed and compared with the data for children and newborns from the national bacterial resistance surveillance report. Among the 209 bacterial strains isolated from infected neonates, 90 were gram-positive, including the four most common isolates: coagulase-negative Staphylococcus, Staphylococcus aureus, Enterococcus, and Streptococcus agalactiae. The remaining 119 strains were gram-negative and included Klebsiella pneumoniae, Acinetobacter baumannii, and Enterobacter aerogenes. The drug sensitivity results showed that the methicillin-resistant Staphylococcus aureus isolates were sensitive to linezolid, vancomycin, rifampicin, levofloxacin, and gentamicin. All Klebsiella pneumoniaisolates were sensitive to amikacin, ertapenem, imipenem, and gentamicin. These two strains were resistant to other antibiotics to varying degrees. Understanding the distribution and drug resistance of bacterial pathogens is vital for guiding the rational selection of antibiotics and reducing neonatal mortality and nosocomial infections.

Structure of a unique fucose-containing exopolysaccharide from Sayram ketteki yoghurt and its anti-MRSA biofilm effect

In this work, we reported an in situ exopolysaccharide (in situ-EPS1) containing rare fucose produced by Lactobacillus helveticus MB2-1 in Sayram ketteki yoghurt, which made it unique. Its fine structure was characterized by GPC, HPLC, FT-IR, GC–MS,1HNMR and 13CNMR together with two-dimensional (2D) NMR spectra. The results revealed that in situ-EPS1 was a new heteropolysaccharide with molecular weight of 1.06 × 105 Da, and was composed of mannose, rhamnose, glucose, galactose and fucose with the following repeating units. [Display omitted] Furthermore, the in situ-EPS1 exhibited significant antibiofilm effect against Methicillin-resistant Staphylococcus aureus (MRSA). Notably, the in situ-EPS1 did not interfere with the planktonic growth of MRSA strain, whereas inhibited its cell metabolic activity and the transcription of genes related to biofilm formation. This unique antibiofilm but non-antibacterial mechanism supposedly prevented the development of bacterial drug resistance, which may open a new door to fight against these drug-resistant microorganisms.

Progress of Research on the Application of Triple Antibiotic Paste and Hydrogel Scaffold Materials in Endodontic Revascularization: A Systematic Review.

Objective To evaluate the application of hydrogel scaffold materials and triple antibiotic paste in endodontic regeneration through literature review. Methods An electronic search of the literature published on PubMed, Wangfang database, and CNKI database using the search terms “endodontic regeneration,” “pulp blood flow reconstruction,” “recanalization,” “triple antibiotic paste,” and “scaffold material” was conducted. The searched literature was used for analysis. Results and Conclusion. Hydrogels regulate stem cell fates, modulate growth factor release, and encapsulate antibacterial and anti-inflammatory drugs. The triple antibiotic paste is composed of metronidazole, ciprofloxacin, and minocycline, which exhibits promising antibacterial effects and duration at appropriate concentrations, with low cytotoxicity, and effectively promotes the preservation and regeneration of pulp tissues and the formation of dental hard tissues. However, issues such as tooth discoloration and bacterial drug resistance also exist. The present article reviews the progress of research on the application of hydrogel scaffold materials and triple antibiotic paste in endodontic revascularization.

In-situ synthesis silver nanoparticles in chitosan/Bletilla striata polysaccharide composited microneedles for infected and susceptible wound healing

A novel antibacterial strategy is urgently required to develop for solving bacterial biofilm obstruction and bacterial drug resistance in the infected wound healing process. Herein, the Chitosan/Bletilla striata polysaccharide composited microneedles were prepared by chitosan, tannic acid, AgNO3 and Bletilla striata polysaccharide through step centrifugation. In our design system, the porous structure of microneedles gradually disappeared, and the mechanical properties were significantly improved after multiple fillings. Ag+ is reduced in-situ to silver nanoparticles by the abundant polyphenols of tannic acid, displaying antibacterial effects both in vitro and vivo, even for methicillin resistant Staphylococcus aureus. The addition of Bletilla striata polysaccharide increased the ability of piercing biofilm and promoted wound healing. The microneedles exhibited good biocompatibility and with function of piercing the bacterial biofilms, scavenging excessive free radicals, inhibiting inflammatory factors, and promoting wound healing. Therefore, the multifunctional composited microneedles show great potential to promote infected and susceptible wound healing.

Towards Innovative Antibacterial Correctors for Cystic Fibrosis Targeting the Lung Microbiome with a Multifunctional Effect.

Cystic fibrosis (CF) is a genetic disease caused by loss-of-function mutations in the CFTR gene, which codes for a defective ion channel. This causes an electrolyte imbalance and results in a spiral of negative effects on multiple organs, most notably the accumulation of thick mucus in the lungs, chronic respiratory tract infections and inflammation leading to pulmonary exacerbation and premature death. Progressive decline of lung function is mainly linked to persistent or recurring infections, mostly caused by bacteria, which require treatments with antibiotics and represent one of the major life-limiting factors in subjects with CF. Treatment of such a complex disease require multiple drugs with a consequent therapeutic burden and complications caused by drug-drug interactions and rapid emergence of bacterial drug resistance. We report herein our recent efforts in developing innovative multifunctional antibiotics specifically tailored to CF by a direct action on bacterial topoisomerases and a potential indirect effect on the pulmonary mucociliary clearance mediated by ΔF508-CFTR correction. The obtained results may pave the way for the development of a simplified therapeutic approach with a single agent acting as multifunctional Antibacterial-Corrector.

Investigation of Adsorptive Properties of Surfactant Modified Sepiolite for Removal of Ciprofloxacin

Pharmaceutical residues, which are considered as emerging contaminants, have been frequently detected in various water including treated water, surface water, and underground water. Furthermore, it may pose a serious risk to the living organisms by enhancing bacterial drug resistance. However, the removal of CIP from aqueous solution is difficult by present water treatment methods. The previous study indicated that the removal of CIP by conventional wastewater treatment technologies is generally incomplete. The aim of this study was to evaluate the efficiency of surfactant (cetyltri-methyl- ammonium bromide)-modified Sepiolite (SMS) for Ciprofloxacin antibiotics (CIP) adsorption in a batch mode technique. The effects of different system variables, adsorbent dosage, initial CIP concentration, temperature contact time were investigated and optimal experimental conditions were ascertained. The results showed that as the amount of the adsorbent is increased, the percentage of CIP removal increase accordingly. Optimum temperature value for CIP adsorption was 50 . Maximum CIP was sequestered within 60 min from the start of every experiment. The results also showed that the best test conditions were obtained at i) initial concentration of CIP 10 mg/L and adsorbent dosage 2 g/L as working solution have been selected as the optimum conditions by the batch process; ii) the removal percentage and the maximum adsorption capacity were found to be 99.1% and 63.84 mg/g iii) Four well-known kinetic models, the pseudo-first- and pseudo-second-order, Elovich and Intra-particle diffusion were used to correlate the adsorption kinetic data, with the pseudo-second-order model giving better results; iv) Negative value of ∆Go and positive value of ∆Hº indicates the feasibility of the process and indicates the spontaneous and endothermic nature of the adsorption; v) SMS adsorbent can be an attractive option for CIP antibiotic removal from diluted industrial effluents since test reaction made on simulated antibiotic wastewater showed better removal percentage of CIP.

Discovery of novel phenylhydrazone-based oxindole-thiolazoles as potent antibacterial agents toward Pseudomonas aeruginosa

With the soaring of bacterial infection and drug resistance, it is imperative to exploit new efficient antibacterial agents. This work constructed a series of unique phenylhydrazone-based oxindole-thiolazoles to combat monstrous bacterial resistance. Some target molecules showed potent antibacterial activity, among which oxindole-thiolimidazole derived carboxyphenylhydrazone 4e exhibited an 8-fold stronger inhibitory ability than norfloxacin on the growth of P. aeruginosa, with MIC value of 1 μg/mL. Compound 4e with imperceptible hemolysis could hamper bacterial biofilm formation and significantly impede the development of bacterial resistance. Subsequent mechanism studies demonstrated that 4e could destruct bacterial cytoplasmic membrane, causing the leakage of cellular contents (protein and nucleic acid). Moreover, metabolic stagnation and intracellular oxidative stress caused by 4e expedited the death of bacteria. Furthermore, molecule 4e existed supramolecular interactions with DNA to block DNA proliferation. These research results provided a promising light for phenylhydrazone-based oxindole-thiolazoles as novel potential antibacterial agents.

Determinants of late neonatal nosocomial infection: a case-control study in Ceará.

ABSTRACTOBJECTIVES To assess the determining factors of late healthcare-associated infections (HAIs) and bacterial multiple drug resistance in neonatal intensive care.METHODS This is a case-control study, conducted between January 2013 and December 2017, in a neonatal intensive care unit in the state of Ceará, Brazil. Newborns showing late HAIs were considered cases and those without infection, the control. Variables with p-values ≤ 0.05 in our initial bivariate regressive analysis were included in a non-conditional hierarchical logistic model for multivariate analysis. P-values below 0.01 were considered significant.RESULTS Of the 1,132 participants, 427 (37.7%) showed late healthcare-associated infections. Of these, 54 (12.6%), positive blood cultures, of which 14.9% contained multidrug-resistant bacteria. Bivariate analysis showed the protective effect of the feminine phenotype (OR = 0.71; 95%CI: 0.56–0.90) and of gestational ages ≥ 34 weeks (OR = 0.48; 95%CI: 0.30–0.75). In earlier-born preterm infants, late infections were 18 times more likely in those with less than 30 week-gestations (OR = 18.61; 95%CI: 9.84–35.22) and four times higher in those weighing less than 1,500 g (OR = 4.18; 95%CI: 3.12–5.61). Mechanical ventilation increased infection odds by more than seven times (OR = 7.14; 95%CI: 5.26–9.09); as did parenteral nutrition (OR = 5.88; 95%CI: 4.54–7.69); central venous catheters (OR = 10.00; 95%CI: 6.66–16.66); the number of catheters used (OR = 3.93; 95%CI: 3.02–5.12); surgery (OR = 4.00; 95%CI: 2.27–7.14); and hospitalization time (OR = 1.06; 95%CI: 1.05–1.07). The association between preterm infants with less than 30 week-gestations (OR = 5.62; 95%CI: 1.83–17.28); mechanical ventilation (OR = 1.84; 95%CI: 1.26–2.68); central venous catheters (OR = 2.48; 95%CI: 1.40–4.37); and hospitalization time (OR = 1.06; 95%CI: 1.05–1.07) remained significant after adjustment. Among deaths, 41 (55.4%) were associated with late infections.CONCLUSION Better practices should be adopted in caring for the premature, as well as in the rational use of procedures, to avoid late healthcare-associated infections, preventable deaths, and risks of bacterial multiple drug resistance and environmental contamination.

Mutations compensating for the fitness cost of rifampicin resistance in Escherichia coli exert pleiotropic effect on RNA polymerase catalysis.

The spread of drug-resistant bacteria represents one of the most significant medical problems of our time. Bacterial fitness loss associated with drug resistance can be counteracted by acquisition of secondary mutations, thereby enhancing the virulence of such bacteria. Antibiotic rifampicin (Rif) targets cellular RNA polymerase (RNAP). It is potent broad spectrum drug used for treatment of bacterial infections. We have investigated the compensatory mechanism of the secondary mutations alleviating Rif resistance (Rifr) on biochemical, structural and fitness indices. We find that substitutions in RNAP genes compensating for the growth defect caused by βQ513P and βT563P Rifr mutations significantly enhanced bacterial relative growth rate. By assaying RNAP purified from these strains, we show that compensatory mutations directly stimulated basal transcriptional machinery (2–9-fold) significantly improving promoter clearance step of the transcription pathway as well as elongation rate. Molecular modeling suggests that compensatory mutations affect transcript retention, substrate loading, and nucleotidyl transfer catalysis. Strikingly, one of the identified compensatory substitutions represents mutation conferring rifampicin resistance on its own. This finding reveals an evolutionary process that creates more virulent species by simultaneously improving the fitness and augmenting bacterial drug resistance.

A dynamic covalent polymeric antimicrobial for conquering drug-resistant bacterial infection.

Increasing bacterial drug resistance to antibiotics has posed a major threat to contemporary public health, which resulted in a large number of people suffering from serious infections and ending up dying without any effective therapies every year. Here, a dynamic covalent polymeric antimicrobial, based on phenylboronic acid (PBA)-installed micellar nanocarriers incorporating clinical vancomycin and curcumin, is developed to overcome drug-resistant bacterial infections. The formation of this antimicrobial is facilitated by reversible dynamic covalent interactions between PBA moieties in polymeric micelles and diols in vancomycin, which impart favorable stability in blood circulation and excellent acid-responsiveness in the infection microenvironment. Moreover, the structurally similar aromatic vancomycin and curcumin molecules can afford π-π stacking interaction to realize simultaneous delivery and release of payloads. In comparison with monotherapy, this dynamic covalent polymeric antimicrobial demonstrated more significant eradication of drug-resistant bacteria in vitro and in vivo due to the synergism of the two drugs. Furthermore, the achieved combination therapy shows satisfied biocompatibility without unwanted toxicity. Considering various antibiotics contain diol and aromatic structures, this simple and robust strategy can become a universal platform to combat the ever-threatening drug-resistant infectious diseases.