Antibiotic-resistant Gram-negative Bacteria Research Articles

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

SummaryBackgroundRates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings.MethodsFor this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681.FindingsWe identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1–31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8–10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6–36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3–47·6; I2 =98%) than in other migrant groups (6·6%, 1·8–11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1–55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1–32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations.InterpretationMigrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration.FundingUK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London.

Genomic epidemiology of multidrug-resistant Gram-negative organisms.

The emergence and spread of antibiotic-resistant Gram-negative bacteria (rGNB) across global healthcare networks presents a significant threat to public health. As the number of effective antibiotics available to treat these resistant organisms dwindles, it is essential that we devise more effective strategies for controlling their proliferation. Recently, whole-genome sequencing has emerged as a disruptive technology that has transformed our understanding of the evolution and epidemiology of diverse rGNB species, and it has the potential to guide strategies for controlling the evolution and spread of resistance. Here, we review specific areas in which genomics has already made a significant impact, including outbreak investigations, regional epidemiology, clinical diagnostics, resistance evolution, and the study of epidemic lineages. While highlighting early successes, we also point to the next steps needed to translate this technology into strategies to improve public health and clinical medicine.

Видовая струк- тура и молекулярно-генетическая характеристика антибио- тикорезистентных штаммов грамотрицательных микроорганизмов, выделенных от пациентов урологического отделения

To analyze the composition and molecular mechanisms of antibiotic resistance of Gram-negative bacteria - pathogens of urinary tract infections (UTIs) in adult patients living in the city of Almaty. The study examined the etiological composition and antibiotic susceptibility of clinically significant isolates of bacteria and fungi ( more or equal 103) isolated from the urine of the patients of the Department of Urology of the Almaty city Central Clinical Hospital No. 12. The production of extended-spectrum beta-lactamases (ESBL) in antibiotic-resistant strains was determined using a phenotypic method with the double disk test. Detection of class A genes for cultures with confirmed ESBL phenotypes (TEM-1, CTX-M1, SHV, OXA) and carbapenemases of class B metallo--lactamases (VIM-2) genes was performed by PCR. Among the isolates obtained from patients, the species of Enterobacteriaceae family in the etiological composition of the UTI pathogens comprised 44.8% including E. coli (31%), K. pneumoniae (4.6%). The most effective drugs against all types of Enterobacteria were carbapenems (96.3-100%). E.coli showed highest sensitivity to nitrofurantoin (96.3%), amikacin (92.6%) and cefoxitin (81.5%). The high rate of resistance to III-IV generation cephalosporins among of E. coli (44.4%) and K. pneumoniae (50%) species was due to the production of ESBL types CTX-M1 and OXA. The proportion of non-fermenting Gram-negative bacteria in the etiological composition of UTI pathogens was 3.5%. Among them, there was a strain producing the metal -lactamase (VIM-2), characterized by absolute resistance to antibiotics of all classes, including carbapenems. The findings on sensitivity profiles and molecular genetic mechanisms of resistance of Gram-negative uropathogens are unique for the Almaty region provides the rationale for developing a local strategy for rational antibiotic therapy. Timely microbiological diagnosis and strict adherence to infection control in a specific hospital are the only way to contain the spread of ESBL and metal -lactamase.

Prevalence and pattern of antibiotic resistance of gram-negative bacteria isolated from urinary tract infections in patients referring to Neka laboratories-Iran

Introduction: Urinary tract infection (UTI) is one of the most common bacterial infections. Increased drug resistance has identified the need to evaluate antibiotic resistance patterns to improve experimental therapy. The aim of this study was to identify bacterial agents and determine their drug resistance pattern in patients referring to the Neka diagnostic laboratories. Methods: This descriptive cross-sectional study was conducted from December 2016 to April 2017 in patients referred to the Neka Diagnostic Laboratories. Morphological study and identification of isolated bacteria by using hot dyeing and differential biochemical tests were performed. Antibiotic resistance of bacteria was determined by Disc diffusion method in Muller Hinton Agar medium. Results: Of the 573 patients, the most commonly isolated bacteria in the urine included 258 isolates of Escherichia coli (45%), 69 isolates of Enterobacter (12%), 18 isolates of Klebsiella (3.14%), and 7 Pseudomonas isolates (1.22%). Escherichia coli isolates showed the highest and lowest resistance, respectively, to Sulfamethoxazole (30.23%) and Norfloxacin (0.39%) and to the highest sensitivity to Gentamicin (56.59%). Conclusion: The results of this study indicate an increase in the resistance of the strains of E.coli to the Sulfamethoxazole and Ciprofloxacin antibiotics, which may be due to the overdose of these antibiotics. The report of antibiotic susceptibility to commonly occurring organisms in this area can be considered by physicians in experimental treatments.

Automated annotation of mobile antibiotic resistance in Gram-negative bacteria: the Multiple Antibiotic Resistance Annotator (MARA) and database.

Multiresistance in Gram-negative bacteria is often due to acquisition of several different antibiotic resistance genes, each associated with a different mobile genetic element, that tend to cluster together in complex conglomerations. Accurate, consistent annotation of resistance genes, the boundaries and fragments of mobile elements, and signatures of insertion, such as DR, facilitates comparative analysis of complex multiresistance regions and plasmids to better understand their evolution and how resistance genes spread. To extend the Repository of Antibiotic resistance Cassettes (RAC) web site, which includes a database of 'features', and the Attacca automatic DNA annotation system, to encompass additional resistance genes and all types of associated mobile elements. Antibiotic resistance genes and mobile elements were added to RAC, from existing registries where possible. Attacca grammars were extended to accommodate the expanded database, to allow overlapping features to be annotated and to identify and annotate features such as composite transposons and DR. The Multiple Antibiotic Resistance Annotator (MARA) database includes antibiotic resistance genes and selected mobile elements from Gram-negative bacteria, distinguishing important variants. Sequences can be submitted to the MARA web site for annotation. A list of positions and orientations of annotated features, indicating those that are truncated, DR and potential composite transposons is provided for each sequence, as well as a diagram showing annotated features approximately to scale. The MARA web site (http://mara.spokade.com) provides a comprehensive database for mobile antibiotic resistance in Gram-negative bacteria and accurately annotates resistance genes and associated mobile elements in submitted sequences to facilitate comparative analysis.

Making Sense of Antimicrobial Resistance Surveillance: A successful intervention

Background: The intensive care units are epicenters for the emergence of antibiotic resistant Gram-negative bacteria because of the high use of antibiotics, prolonged hospital stay, reduced patient immunity, use of medical devices, and the frequent contact between healthcare workers and patients. Surveillance of bacterial resistance is the key element to understand the size of the problem, drive interventions, and measures the effect of these measures. Several reports have linked the use of third generation cephalosporins with β-lactam resistance in gram-negative bacteria. Several strategies were introduced by the Antibiotic Stewardship Programs to reduce antibiotic resistance but the efficacies of these interventions are not well studied. Methods: The Microbiology Laboratory of Hamad Medical Corporation (HMC) monitors antimicrobial resistance by continuous surveillance using the National Committee for Clinical Laboratory Standards (NCCLS) - currently Clinical Laboratory Standards Institute interpretive criteria. Surveillance data were released annually and shared with clinicians and policy makers for review of the antibiotic policy and the antibiotic formulary. Results: Surveillance data in 2001 showed high level β-lactam antibiotics resistance and high level production of extended spectrum β-lactamases (ESBL) among gram-negative bacteria. As a result, the Hospital Antibiotic Policy Committee decided to withdraw ceftazidime a third –generation cephalosporin known to be a strong inducer of ESBL, from the hospital formulary. Subsequent resistance surveillance over the following three years in the Medical Intensive Care unit (MICU) demonstrated a gradual drop in the resistance of Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli; the commonest isolated gram negative bacteria from MICU), not only to third and fourth generation cephalosporins, but also to Piperacillin – Tazobactam in spite of the increased use of the later drug in the MICU. Discussion and conclusion: Antibiotic resistance is an increasing global problem. Surveillance studies are needed to monitor resistance development, to guide local empirical therapy, and to implement timely and adequate countermeasures. Since resistance development is an evolutionary process, constant surveillance is necessary to gain insight into the problem in a timely fashion. Several measures were taken including antibiotic cycling, antibiotic rotation and restriction. Restriction of the use of Ceftazidime resulted in a significant drop in the resistance of the common Gram-negative bacteria to the betalactam antibiotics. The sustainability and efficacy of these measures need to be monitored over time.

Identification of Antibiotic Resistant Gram-Negative Bacteria in a Popular Street-Food Item (Chatpati) in Dhaka University Campus, Bangladesh

Presence of antibiotic resistant bacteria in street-foods has become a global health concern. In this study, we have thoroughly investigated the bacteriological quality of Chatpati (CHT) samples collected from 7 different locations of Dhaka University campus. Various selective and differential media, Gram staining and biochemical tests were carried out for isolation, enumeration and characterization of the isolates. The total bacterial count varied in samples from 7 locations ranging from 1.1x10³ to 4.1x106 CFU/g. Klebsiella spp., Escherichia coli (E. coli), Enterobacter spp., Vibrio spp., Proteus spp., Pseudomonas aeruginosa and Aeromonas spp. were identified in the collected CHT samples. Isolates were then subjected to antibiotic susceptibility test. For antibiogram profiling, Ampicillin, Colistin, Chloramphenicol, Ceftriaxone, Ciprofloxacin and Nitrofurantoin were employed in this study. Multiple antibiotic resistance index (MRI%) of the isolates were found to be ranged from 16.67 to 66.67%. Majority of the isolates showed resistance against Ampicillin and Nitrofurantoin. Therefore, it may be concluded that the consumption of CHT from this area may be severely detrimental to health due to the presence of antibiotic resistant bacteria.

Structure, Function of Serine and Metallo-β-lactamases and their Inhibitors.

Antibiotic resistance in gram-negative bacteria has emerged as a major health threat that occurs because these bacteria actively produce β-lactamases responsible for the inactivation of β-lactam antibiotics. The first β lactamase was reported in E. coli back in 1940, before the release of the first antibiotic penicillin in clinical settings. Later on, large numbers of β-lactamases have been discovered in Gram-positive, Gram-negative bacteria as well as mycobacteria. Currently, numerous three-dimensional structures of serine and metallo-β-lactamases have been solved. The serine β-lactamases essentially consist of two structural domains (an all α and an α/β domain) and the active site is located at the groove between the two domains. The catalysis of serine β-lactamase proceeds via acylation and deacylation reactions. The three dimensional structure of metallo-β-lactamases displayed a common four layer "αβ/βα" motif, with a central "ββ"- sandwich by Zn2+ ion(s), and two α-helices are located on the either side. The active site of metallo-β-lactamases contain either 1 or 2 Zn2+ ions, which is coordinated to metal ligating amino acids and polarized water molecule(s) necessary for the hydrolysis of β-lactam antibiotics. Keeping the above views in mind, in this review we have shed light on the current knowledge of the structures and mechanisms of catalysis of serine and metallo-β-lactamases. Moreover, mutational studies on β-lactamases highlight the importance of the active site residues and residues in the vicinity to the active site pocket in the catalysis. To combat bacterial infections more effeciently novel inhibitors of β-lactamase in combination with antibiotics have been used which also form the theme of the review.

Dual Regulation of the Small RNA MicC and the Quiescent Porin OmpN in Response to Antibiotic Stress in Escherichia coli.

Antibiotic resistant Gram-negative bacteria are a serious threat for public health. The permeation of antibiotics through their outer membrane is largely dependent on porin, changes in which cause reduced drug uptake and efficacy. Escherichia coli produces two major porins, OmpF and OmpC. MicF and MicC are small non-coding RNAs (sRNAs) that modulate the expression of OmpF and OmpC, respectively. In this work, we investigated factors that lead to increased production of MicC. micC promoter region was fused to lacZ, and the reporter plasmid was transformed into E. coli MC4100 and derivative mutants. The response of micC–lacZ to antimicrobials was measured during growth over a 6 h time period. The data showed that the expression of micC was increased in the presence of β-lactam antibiotics and in an rpoE depleted mutant. Interestingly, the same conditions enhanced the activity of an ompN–lacZ fusion, suggesting a dual transcriptional regulation of micC and the quiescent adjacent ompN. Increased levels of OmpN in the presence of sub-inhibitory concentrations of chemicals could not be confirmed by Western blot analysis, except when analyzed in the absence of the sigma factor σE. We suggest that the MicC sRNA acts together with the σE envelope stress response pathway to control the OmpC/N levels in response to β-lactam antibiotics.

Fluorescence enlightens RND pump activity and the intrabacterial concentration of antibiotics

To understand antibiotic resistance in Gram-negative bacteria, a key point is to investigate antibiotic accumulation, which is defined by influx and efflux. Several methods exist to evaluate membrane permeability and efflux pump activity, but they present disadvantages and limitations. An optimized spectrofluorimetric method using intrinsic tryptophan fluorescence as an internal standard, as well as a complementary microfluorimetric assay following time-course accumulation in intact individual cells, have been developed. Comparing the latter population and single cell approaches can lead to an understanding of phenotypic heterogeneity within a population. The two methodologies lead to determination of parameters, concentration, accumulation rates and localization that contribute to emerging concepts (RTC2T, SICAR) with the aim of identifying and detailing antibiotic chemotypes involved in influx/efflux.

Subfunctionalization influences the expansion of bacterial multidrug antibiotic resistance

BackgroundAntibiotic resistance is a major problem for human health. Multidrug resistance efflux pumps, especially those of the Resistance-Nodulation-Cell Division (RND) family, are major contributors to high-level antibiotic resistance in Gram-negative bacteria. Most bacterial genomes contain several copies of the different classes of multidrug resistance efflux pumps. Gene duplication and gain of function by the duplicate copies of multidrug resistance efflux pump genes plays a key role in the expansion and diversification of drug-resistance mechanisms.ResultsWe used two members of the Burkholderia RND superfamily as models to understand how duplication events affect the antibiotic resistance of these strains. First, we analyzed the conservation and distribution of these two RND systems and their regulators across the Burkholderia genus. Through genetic manipulations, we identified both the exact substrate range of these transporters and their eventual interchangeability. We also performed a directed evolution experiment, combined with next generation sequencing, to evaluate the role of antibiotics in the activation of the expression of these systems. Together, our results indicate that the first step to diversify the functions of these pumps arises from changes in their regulation (subfunctionalization) instead of functional mutations. Further, these pumps could rewire their regulation to respond to antibiotics, thus maintaining high genomic plasticity.ConclusionsStudying the regulatory network that controls the expression of the RND pumps will help understand and eventually control the development and expansion of drug resistance.

Pharmacodynamics of fosfomycin against ESBL- and/or carbapenemase-producing Enterobacteriaceae.

The increase in antibiotic resistance in Gram-negative bacteria and the limited therapeutic options due to the shortage of new antibiotics have increased the interest of the 'old' antibiotic fosfomycin in the treatment of infections. However, there are contradictory reports on the pharmacodynamics of and emergence of resistance to fosfomycin. Time-kill assays were performed with 11 ESBL-positive and 3 ESBL-negative strains, exposing the bacteria to 2-fold static concentrations from 0.125× to 32× MIC. The sigmoid maximum effect (Emax) model was fitted to the time-kill curve data. Amplification of resistance over time was evaluated under various conditions of selective pressure by plating on 16× MIC plates. Fosfomycin was bactericidal for all strains within 8 h. Using the Emax model, no significant differences between strains were observed for the pharmacodynamic parameters. However, the large variation in Hill slope factors for Escherichia coli of 0.87 up to 4.02 indicates that the killing behaviour appears to be more time dependent for some strains but concentration dependent for others. In the fosfomycin-exposed cultures under low and high selective pressure (≥2× MIC) the median resistance proportions between the resistant and total population increased from ≤2 × 10-6 (T = 0 h) to 0.652-0.899 (T = 24 h). Resistance appeared stable after repeated subculturing. Killing behaviour of fosfomycin does not only differ between species but also within species and may have an impact on the design of optimal dosing regimens. Although fosfomycin was bactericidal against all strains (re)growth of resistant subpopulations occurred relatively fast. This may limit the use of fosfomycin as a single drug therapy.

Clinical aspects of severe infections caused by antibiotic-resistant Gram-negative bacteria. The Empire strikes back?

In our days, growing incidence of antibiotic resistant bacteria has become an eminent public health problem. For survival Gram-negative species possess several different tools to withstand antibiotics: they produce degrading and modifying enzymes, decrease their permeability or expel drug molecules. An increasing proportion of severe nosocomial infections are caused by strains resistant to several antimicrobials (multiresistant, extensively resistant or panresistant species). Development of new antibiotic compounds may serve as a possible solution to this problem. Ceftolozane-tazobactam is a new beta-lactam+beta-lactamase-inhibitor combination resistant to most extended spectrum beta-lactamase enzymes showing excellent anti-Pseudomonas activity. It is also effective against strains when beta-lactam resistance is related to porin loss or efflux pump activity. The spectrum of ceftazidime-avibactam also includes carbapenemase-(KPC)-producing Enterobacteriaceae. In addition to novel therapy, an effective infection control system together with the prudent use of antimicrobials (antimicrobial stewardship) is of paramount importance. Orv Hetil. 2017; 158(39): 1528-1534.

Transmission of Resistant Gram-Negative Bacteria to Health Care Worker Gowns and Gloves during Care of Nursing Home Residents in Veterans Affairs Community Living Centers.

The objectives of the study were to estimate the risk of transmission of antibiotic-resistant Gram-negative bacteria (RGNB) to gowns and gloves (G&G) worn by health care workers (HCWs) when providing care to nursing home residents and to identify the types of care and resident characteristics associated with transmission. A multicenter, prospective observational study was conducted with residents and HCWs from Veterans Affairs (VA) nursing homes. Perianal swabs to detect RGNB were collected from residents. HCWs wore G&G during usual care activities, and the G&G were swabbed at the end of the interaction in a standardized manner. Transmission of RGNB from a colonized resident to G&G by type of care was measured. Odds ratios (ORs) associated with type of care or resident characteristics were estimated. Fifty-seven (31%) of 185 enrolled residents were colonized with ≥1 RGNB. RGNB transmission to HCW gloves or gowns occurred during 9% of the interactions (n = 905): 7% to only gloves and 2% to only gowns. Bathing the resident and providing hygiene and toilet assistance were associated with a high risk of transmission. Glucose monitoring and assistance with feeding or medication were associated with a low risk of transmission. In addition, antibiotic use by the resident was strongly associated with greater transmission (OR, 2.51; P < 0.01). RGNB were transferred to HCWs during ∼9% of visits. High-risk types of care were identified for which use of G&G may be prioritized. Antibiotic use was associated with 2.5 times greater risk of transmission, emphasizing the importance of antibiotic stewardship. (This study has been registered at ClinicalTrials.gov under registration no. NCT01350479.).

Exploring bacterial outer membrane barrier to combat bad bugs.

One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels.

Synthesis and biological evaluation of Aspergillomarasmine A derivatives as novel NDM-1 inhibitor to overcome antibiotics resistance

The β-lactam antibiotic resistance of Gram-negative bacteria has shown to be a critical global health problem. One of the primary reasons for the drug resistance is the existence of β-lactamases especially metallo-β-lactamases such as New Delhi metallo-β-lactamase (NDM-1) and Verona Integron-encoded metallo-β-lactamase (VIM-2). The fungal natural product Aspergillomarasmine A (AMA) has proven to be a promising inhibitor of NDM-1 and VIM-2 both in vitro and in vivo. Seven new analogues of AMA were synthesized by utilizing different strategies. The biological evaluation of these analogues was performed to study the structure-activity relationship of AMA both in vitro and in vivo. Remarkably, the lead compound 4 showed synergistic effect in combination with Meropenem to overcome the antibiotic resistance of the Gram-negative bacteria such as K. pneumoniae (BAA-2146) expressing NDM-1.

Antibacterial small molecules targeting the conserved TOPRIM domain of DNA gyrase.

To combat the threat of antibiotic-resistant Gram-negative bacteria, novel agents that circumvent established resistance mechanisms are urgently needed. Our approach was to focus first on identifying bioactive small molecules followed by chemical lead prioritization and target identification. Within this annotated library of bioactives, we identified a small molecule with activity against efflux-deficient Escherichia coli and other sensitized Gram-negatives. Further studies suggested that this compound inhibited DNA replication and selection for resistance identified mutations in a subunit of E. coli DNA gyrase, a type II topoisomerase. Our initial compound demonstrated weak inhibition of DNA gyrase activity while optimized compounds demonstrated significantly improved inhibition of E. coli and Pseudomonas aeruginosa DNA gyrase and caused cleaved complex stabilization, a hallmark of certain bactericidal DNA gyrase inhibitors. Amino acid substitutions conferring resistance to this new class of DNA gyrase inhibitors reside exclusively in the TOPRIM domain of GyrB and are not associated with resistance to the fluoroquinolones, suggesting a novel binding site for a gyrase inhibitor.

European and Russian physician awareness of best management approaches for infections due to antibiotic-resistant Gram-negative bacteria

Objectives: The rapid spread of infections due to antibiotic-resistant, Gram-negative bacteria in Europe and surrounding regions requires a heightened level of awareness among physicians within their practice settings.Methods: We surveyed 800 physicians who treat these infections across France, Germany, Spain, Italy, and Russia to assess their awareness of best management approaches.Results: We found that more than two-thirds do not consider themselves highly aware of best management practices. The respondents are facing these resistant infections as evidenced by the antibiotics they report using and their stated interest in newer agents. Respondents indicated that precious time is lost waiting for culture results, but also said they will need more information about accuracy, use, and costs for adopting rapid molecular testing.Conclusions: The survey further identified the need for treatment guidelines and clinical decision support tools that can be applied at the bedside.

Detection of emerging antibiotic resistance in bacteria isolated from subclinical mastitis in cattle in West Bengal

Aim:The aim of this work was to detect antibiotic resistance in Gram-negative bacteria isolated from subclinical mastitis in cattle in West Bengal.Materials and Methods:The milk samples were collected from the cattle suffering with subclinical mastitis in West Bengal. The milk samples were inoculated into the nutrient broth and incubated at 37°C. On the next day, the growth was transferred into nutrient agar and MacConkey agar. All the pure cultures obtained from nutrient agar slant were subjected to Gram-staining and standard biochemical tests. All the bacterial isolates were tested in vitro for their sensitivity to different antibiotics commonly used in veterinary practices. All Gram-negative isolates including positive control were subjected to polymerase chain reaction (PCR) for detection of blaCTX-M, blaTEM, blaSHV, blaVIM, tetA, tetB, tetC, and tetM genes considered for extended-spectrum β-lactamase (ESBL), metallo-β-lactamase, and tetracycline resistance.Results:In total, 50 Gram-negative organisms (Escherichia coli, Proteus, Pseudomonas, Klebsiella, and Enterobacter) were isolated from milk samples of subclinical mastitis infected cattle. Among these Gram-negative isolates, 48% (24/50) were found either ESBL producing or tetracycline resistant. Out of total 50 Gram-negative isolates, blaCTX-M was detected in 18 (36%) isolates, and 6 (12%) harbored blaTEM genes in PCR. None of the isolates carried blaSHV genes. Further, in this study, 5 (10%) isolates harbored tet(A) gene, and 8 (16%) isolates carried tet(B) gene. No tet(C) gene was detected from the isolates.Conclusion:This study showed emerging trend of antibiotic-resistant Gram-negative bacteria associated with subclinical mastitis in cattle in West Bengal, India.

Structure-Activity Relationship of Membrane-Targeting Cationic Ligands on a Silver Nanoparticle Surface in an Antibiotic-Resistant Antibacterial and Antibiofilm Activity Assay.

To explore the structure-activity relationship of membrane-targeting cationic ligands on a silver nanoparticle surface in an antibiotic-resistant antibacterial and antibiofilm activity assay, a series of functionalized silver nanocomposites were synthesized. Tuning the structural configuration, molecular weight, and side-chain length of the cationic ligands on the nanoparticle surface provided silver nanocomposites with effective antibacterial activity against both antibiotic-resistant Gram-negative and Gram-positive bacteria, including bacterial biofilms. These silver nanocomposites did not trigger hemolytic activity. Significantly, the bacteria did not develop resistance to the obtained nanocomposites even after 30 generations. A study of the antibacterial mechanism confirmed that these nanocomposites could irreversibly disrupt the membrane structure of bacteria and effectively inhibit intracellular enzyme activity, ultimately leading to bacterial death. The silver nanocomposites (64 μg/mL) could eradicate 80% of an established antibiotic-resistant bacterial biofilm. The strong structure-activity relationship toward antibacterial and antibiofilm activity suggests that variations in the conformational property of the functional ligand could be valuable in the discovery of new nano-antibacterial agents for treating pathogenic bacterial infections.