Mechanisms of gram-positive vancomycin resistance (Review)

Multidrug resistance profile in Lactobacillus delbrueckii: a food industry species with probiotic properties

Lactobacillus delbrueckii, a widely used lactic acid bacterium in the food industry, has been studied for its probiotic properties and reservoir of antibiotic-resistant genes, raising safety concerns for probiotic formulations and fermented products. This review consolidates findings from 60 articles published between 2012 and 2023, focusing on the global antibiotic resistance profile and associated genetic factors in L. delbrueckii strains. Resistance to aminoglycosides, particularly streptomycin, kanamycin, and gentamicin, as well as resistance to glycopeptides (vancomycin), fluoroquinolones (ciprofloxacin), and tetracyclines was predominant. Notably, although resistance genes have been identified, they have not been linked to mobile genetic elements, reducing the risk of dissemination. However, a significant limitation is the insufficient exploration of responsible genes or mobile elements in 80% of studies, hindering safety assessments. Additionally, most articles originated from Asian and Middle Eastern countries, with strains often isolated from fermented dairy foods. Therefore, these findings underscore the necessity for comprehensive analyses of new strains of L. delbrueckii for potential industrial and biotherapeutic applications and in combating the rise of antibiotic-resistant pathogens.

Development of CuO Nanoparticles from the Mucus of Garden Snail Cornu aspersum as New Antimicrobial Agents

Several biologically active compounds involved in the green synthesis of silver and gold nanoparticles have been isolated from snail mucus and characterized. This paper presents a successful method for the application of snail mucus from Cornu aspersum as a bioreducing agent of copper sulfate and as a biostabilizer of the copper oxide nanoparticles (CuONPs-Muc) obtained. The synthesis at room temperature and neutral pH yielded nanoparticles with a spherical shape and an average diameter of 150 nm. The structure and properties of CuONPs-Muc were characterized using various methods and techniques, such as ultraviolet-visible spectroscopy (UV-vis), high-performance liquid chromatography (HPLC), one-dimensional polyacrylamide gel electrophoresis (1D-PAGE), up-conversion infrared spectroscopy Fourier transform (FTIR), scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS), Raman spectroscopy and imaging, thermogravimetric analysis (TG-DSC), etc. Mucus proteins with molecular weights of 30.691 kDa and 26.549 kDa were identified, which are involved in the biogenic production of CuONPs-Muc. The macromolecular shell of proteins formed around the copper ions contributes to a higher efficiency of the synthesized CuONPs-Muc in inhibiting the bacterial growth of several Gram-positive (Bacillus subtilis NBIMCC2353, Bacillus spizizenii ATCC 6633, Staphylococcus aureus ATCC 6538, Listeria innocua NBIMCC8755) and Gram-negative (Escherichia coli ATCC8739, Salmonella enteitidis NBIMCC8691, Salmonella typhimurium ATCC 14028, Stenotrophomonas maltophilia ATCC 17666) bacteria compared to baseline mucus. The bioorganic synthesis of snail mucus presented here provides CuONPs-Muc with a highly pronounced antimicrobial effect. These results will expand knowledge in the field of natural nanomaterials and their role in emerging dosage forms.

Analysis of Antimicrobial Resistance in Bacterial Pathogens Recovered from Food and Human Sources: Insights from 639,087 Bacterial Whole-Genome Sequences in the NCBI Pathogen Detection Database

Understanding the role of foods in the emergence and spread of antimicrobial resistance necessitates the initial documentation of antibiotic resistance genes within bacterial species found in foods. Here, the NCBI Pathogen Detection database was used to query antimicrobial resistance gene prevalence in foodborne and human clinical bacterial isolates. Of the 1,843,630 sequence entries, 639,087 (34.7%) were assigned to foodborne or human clinical sources with 147,788 (23.14%) from food and 427,614 (76.88%) from humans. The majority of foodborne isolates were either Salmonella (47.88%), Campylobacter (23.03%), Escherichia (11.79%), or Listeria (11.3%), and the remaining 6% belonged to 20 other genera. Most foodborne isolates were from meat/poultry (95,251 or 64.45%), followed by multi-product mixed food sources (29,892 or 20.23%) and fish/seafood (6503 or 4.4%); however, the most prominent isolation source varied depending on the genus/species. Resistance gene carriage also varied depending on isolation source and genus/species. Of note, Klebsiella pneumoniae and Enterobacter spp. carried larger proportions of the quinolone resistance gene qnrS and some clinically relevant beta-lactam resistance genes in comparison to Salmonella and Escherichia coli. The prevalence of mec in S. aureus did not significantly differ between meat/poultry and multi-product sources relative to clinical sources, whereas this resistance was rare in isolates from dairy sources. The proportion of biocide resistance in Bacillus and Escherichia was significantly higher in clinical isolates compared to many foodborne sources but significantly lower in clinical Listeria compared to foodborne Listeria. This work exposes the gaps in current publicly available sequence data repositories, which are largely composed of clinical isolates and are biased towards specific highly abundant pathogenic species. We also highlight the importance of requiring and curating metadata on sequence submission to not only ensure correct information and data interpretation but also foster efficient analysis, sharing, and collaboration. To effectively monitor resistance carriage in food production, additional work on sequencing and characterizing AMR carriage in common commensal foodborne bacteria is critical.

Antibiotic Use in Adult Spine Deformity Surgery: Results From the AO Spine Surveillance of the Management of Patients With Adult Spine Deformity

STUDY DESIGN

Cross-sectional international survey with literature review.

OBJECTIVES

To evaluate the evidence for these strategies and to understand the current trends in prophylactic antibiotic use during ASD surgery through an international survey.

METHODS

An online survey was conducted among international AO Spine members regarding the peri-operative management of patients with ASD. The details of perioperative systemic and topical antibiotic use were solicited. Descriptive data were summarized for the responding surgeons who perform at least 10 long-segment fusions of >5 levels extending to the pelvis annually.

RESULTS

The literature supports the use of prophylactic antibiotic effective against gram positive organisms. The use of topical vancomycin remains debated, and there is limited evidence for topical tobramycin use. A total of 116 responses were received. 74 (64%) surgeons use topical vancomycin, most usually deep to the fascia only 45 (61%). The most usual dose used is 1-2 g. 4 (3%) surgeons use topical tobramycin deep to fascia. Following surgery, 90 (78%) surgeons use prophylactic cephalosporin with 3 (3%) using cloxacillin, 5 (4%) using ciprofloxacin and 9 (8%) using vancomycin and 6 (5%) using clindamycin either in addition or alone.

CONCLUSIONS

The present survey identifies a trend towards systemic and topical antibiotic prophylaxis primarily targeted at gram positive pathogens. The use of topical tobramycin, proposedly effective against gram negative infections, remains uncommon. There is a lack of consensus in the selection of perioperative antibiotic prophylaxis, thus a prospective study of the rates of infection with each strategy would be useful to inform guidelines.

Highly Sensitive Cyanine Dyes for Rapid Sensing of NAD(P)H in Mitochondria and First-Instar Larvae of Drosophila melanogaster

We have developed two highly sensitive cyanine dyes, which we refer to as probes A and B. These dyes are capable of quick and sensitive sensing of NAD(P)H. The dyes were fabricated by connecting benzothiazolium and 2,3-dimethylnaphtho[1,2-d]thiazol-3-ium units to 3-quinolinium through a vinyl bond. In the absence of NAD(P)H, both probes have low fluorescence and absorption peaks at 370 and 400 nm, correspondingly. This is because of their two electron-withdrawing acceptor systems with high charge densities. However, when NAD(P)H reduces the probes' electron-withdrawing 3-quinolinium units to electron-donating 1,4-dihydroquinoline units, the probes absorb at 533 and 535 nm and fluoresce at 572 and 586 nm for A and B correspondingly. This creates well-defined donor-π-acceptor cyanine dyes. We successfully used probe A to monitor NAD(P)H levels in live cells during glycolysis, under hypoxic conditions induced by CoCl2 treatment and after treatment with cancer drugs, including cisplatin, camptothecin, and gemcitabine. Probe A was also employed to visualize NAD(P)H in Drosophila melanogaster first-instar larvae. We observed an increase in NAD(P)H levels in A549 cancer cells both under hypoxic conditions and after treatment with cancer drugs, including cisplatin, camptothecin, and gemcitabine.

Environmentally sensitive photosensitizers enable targeted photodynamic ablation of Gram-positive antibiotic resistant bacteria

Bacterial infections remain among the biggest challenges to human health, leading to high antibiotic usage, morbidity, hospitalizations, and accounting for approximately 8 million deaths worldwide every year. The overuse of antibiotics and paucity of antimicrobial innovation has led to antimicrobial resistant pathogens that threaten to reverse key advances of modern medicine. Photodynamic therapeutics can kill bacteria but there are few agents that can ablate pathogens with minimal off-target effects. Methods: We describe nitrobenzoselenadiazoles as some of the first environmentally sensitive organic photosensitizers, and their adaptation to produce theranostics with optical detection and light-controlled antimicrobial activity. We combined nitrobenzoselenadiazoles with bacteria-targeting moieties (i.e., glucose-6-phosphate, amoxicillin, vancomycin) producing environmentally sensitive photodynamic agents. Results: The labelled vancomycin conjugate was able to both visualize and eradicate multidrug resistant Gram-positive ESKAPE pathogens at nanomolar concentrations, including clinical isolates and those that form biofilms. Conclusion: Nitrobenzoselenadiazole conjugates are easily synthesized and display strong environment dependent ROS production. Due to their small size and non-invasive character, they unobtrusively label antimicrobial targeting moieties. We envisage that the simplicity and modularity of this chemical strategy will accelerate the rational design of new antimicrobial therapies for refractory bacterial infections.

No country for old antibiotics! Antimicrobial peptides (AMPs) as next-generation treatment for skin and soft tissue infection

In recent years, the unprecedented rise of bacterial antibiotic resistance together with the lack of adequate therapies have made the treatment of skin infections and chronic wounds challenging, urging the scientific community to focus on the development of new and more efficient treatment strategies. In this context, there is a growing interest in the use of natural molecules with antimicrobial features, capable of supporting wound healing i.e., antimicrobial peptides (AMPs), for the treatment of skin and soft tissue infections. In this review, we give a short overview of the bacterial skin infections as well as some of the classic treatments used for topical application. We then summarize the AMPs classes, stressing the importance of the appropriate selection of the peptides based on their characteristics and physicochemical properties in order to maximize the antibacterial efficacy of the therapeutic systems against multi-drug resistant pathogens. Additionally, the present paper provides a comprehensive and rigorous assessment of the latest clinical trials investigating the efficacy of AMPs in the treatment of skin and soft tissue infections, highlighting the relevant outcomes. Seeking to obtain novel and improved compounds with synergistic activity, while also decreasing some of the known side effects of AMPs, we present two employed strategies using AMPs: (i) AMPs-conjugated nanosystems for systemic and topical drug delivery systems and (ii) antibiotics-peptide conjugates as a strategy to overcome antibiotics resistance. Finally, an important property of some of the AMPs used in wound treatment is highlighted: their ability to help in wound healing by generally promoting cell proliferation and migration, and in some cases re-epithelialization and angiogenesis among others. Thus, as the pursuit of improvement is an ongoing effort, this work presents the advances made in the treatment of skin and soft tissue infections along with their advantages and limitations, while the still remaining challenges are addressed by providing future prospects and strategies to overcome them.

Recent Advances in Strategies to Combat Bacterial Drug Resistance: Antimicrobial Materials and Drug Delivery Systems

Bacterial infection is a common clinical disease. Antibiotics have saved countless lives since their discovery and are a powerful weapon in the fight against bacteria. However, with the widespread use of antibiotics, the problem of drug resistance now poses a great threat to human health. In recent years, studies have investigated approaches to combat bacterial resistance. Several antimicrobial materials and drug delivery systems have emerged as promising strategies. Nano-drug delivery systems for antibiotics can reduce the resistance to antibiotics and extend the lifespan of novel antibiotics, and they allow targeting drug delivery compared to conventional antibiotics. This review highlights the mechanistic insights of using different strategies to combat drug-resistant bacteria and summarizes the recent advancements in antimicrobial materials and drug delivery systems for different carriers. Furthermore, the fundamental properties of combating antimicrobial resistance are discussed, and the current challenges and future perspectives in this field are proposed.

Vankomisine Dirençli Enterococcus faecium: Kısa Bir Derleme

Antimikrobiyal direnç (AMD) ile ilişkili morbidite ve mortalite küresel bir halk sağlığı sorunudur. Sağlık hizmeti ilişkili enfeksiyonlarda sık olarak görülen vankomisine dirençli Enterococcus faecium (VRE), Dünya Sağlık Örgütü’nün AMD’i olan öncelikli patojenler listesinde yüksek öncelik verdiği bir Gram pozitif koktur. Son zamanlarda Türkiye’de invaziv enfeksiyonlarda VRE izolasyon oranı %15.8 bildirilmiştir. Vankomisine direncin ana mekanizması, hedef bölgedeki D-Alanil-D-Alanin terminal molekülünün değişmesi ve ilacın affinitesinin azalmasıdır. Vankomisin direncinden sorumlu olan van geni kromozomal olarak kodlanmakta veya plazmid, transpozon gibi mobil genetik elemanlar ile kazanılmaktadır. Yayılımındaki ana mekanizma, mobil genetik elemanların Enterokoklar veya Staphylococcus aereus gibi farklı tür bakteriler arasında transfer edilebilmeleridir. Bu derlemede PubMed ve Web of Science veritabanlarında “Vankomisin-dirençli Enterococcus faecium”, “Vankomisin direnç mekanizmaları”, “Gram pozitif koklarda vankomisin direnci” terimleri ile arama yapılarak elde edilen literatür verileri özetlenmiş ve önerilerle birlikte kısaca tartışılmıştır.

Intestinal colonization of vancomycin-resistant Enterococcus in children admitted to Mofid children's hospital intensive care unit at admission and at discharge

BACKGROUND

This study aimed to investigate the frequency of intestinal colonization by vancomycin-resistant Enterococcus (VRE) carrying vanA and vanB genes in patients at ICU admission and at discharge from ICU in Mofid children's Hospital, Tehran, Iran.

METHOD

Sampling was performed using rectal swabs and vancomycin susceptibility testing for Enterococcus spp. was carried out using a minimum inhibitory concentration (MIC) assay on Muller Hinton Agar (MHA) medium using an E-test kit. The molecular detection of VRE isolates was performed by the PCR method using the vanA and vanB resistance genes.

RESULTS

A total of 234 and 186 non-duplicate rectal swab samples were collected from patients at ICU admission and at discharge from ICU, respectively. Enterococcus spp. was detected in 34.6% (n = 81/234) of rectal swab samples collected from patients at ICU admission, of which 44.4% (n = 36/81) were VRE isolates. In contrast, the prevalence of Enterococcus spp. and VRE isolates among patients at discharge from ICU was 17.7% (n = 33/186) and 57.6% (n = 19/33), respectively. Out of 19 VRE isolated from patients at ICU admission, 4 (21%) and 1 (5.3%) contained vanA and vanB genes, respectively. In contrast, out of 36 VRE isolated from patients at discharge from ICU, 11 (30.5%) were positive for the vanA gene.

CONCLUSION

Results revealed that the prevalence of Enterococcus spp. among patients at ICU admission was high. However, VRE was frequently isolated from patients who were hospitalized for several days in ICUs. The implementation of proper infection control strategies and the use of suitable protocols to guide the appropriate prescribing of antibiotics are necessary.

Molecular detection and occurrence of vancomycin resistance genes (van A, B, C1, C2/C3) among Enterococcus species isolated from farm ostriches

BACKGROUND

Evaluating the prevalence of vancomycin resistance genes (van genes) in enterococcal isolates from food-producing animals is an important public health issue because of the possibility of resistance genes spread to human.

OBJECTIVES

The present study aimed to determine the occurrence of vancomycin resistance genes among Enterococcus species obtained from ostrich faecal samples.

METHODS

One hundred and twenty-five faecal samples of apparently healthy ostriches from five different farms were investigated. Genes encoding vancomycin resistance were studied by multiplex-PCR, and susceptibility to six antibiotics was evaluated by disk-diffusion method.

RESULTS

In total, 107 Enterococcus spp. isolates were obtained and confirmed by biochemical and molecular tests. Enterococcus faecium was the prevailing species (56 isolates of 107; 52.3%), followed by E. hirae (24 isolates; 22.4%) and E. gallinarum (12 isolates; 11.2%). Of the 107 recovered isolates, 44% harboured at least a type of van genes. vanA, vanC2/3 and vanC1 were identified in 34 (31.7%), 13 isolates (12.1%) and 4 (3.7%) isolates respectively. Additionally, four isolates (E. gallinarum, E. rafinosus) co-harboured the the vanA and vanC1 or vanA and vanC2/3. Enterococcus faecium and Enterococcus hirae strains with the vanA genotype were the most frequent van-carrying enterococci from ostrich faecal samples. Among van-carrying enterococcal isolates, 23.4% were phenotypically resistant to vancomycin. This study revealed a relatively high prevalence (44%) of van-carrying enterococci in ostrich faecal samples.

CONCLUSIONS

Results of the present study suggest that ostrich faeces could be considered as a reservoir of vancomycin resistance genes, especially vanA containing enterococci that could be potentially transferred to human through the food chain.

Detection of Extended-spectrum Beta-lactamases (ESBLs), Carbapenemase, Metallo-β-lactamase Production Bacteria and Antibiotic Susceptibility Pattern in Hospitalized Patients with Ventilator-associated Pneumonia

Background: Due to the increase in microbial resistance, nosocomial multidrug resistance infections, including ventilator-associated pneumonia (VAP), are presently one of the main causes of death in hospitals since they are difficult to treat. Objectives: This study aimed to investigate the bacterial etiology of VAP and their microbial resistance pattern in Dezful Hospital, southwest of Iran. Methods: In this cross-sectional study, 131 bacterial isolates were isolated from the respiratory secretions of the patients with VAP in ICU wards. Antibiotic susceptibility testing (AST) of all isolates was carried out after the identification. Then the extended-spectrum beta-lactamases (ESBLs), carbapenemase, and metallobetalactamase were identified by phenotyping and genotyping. Results: The most frequent isolates were Staphylococcus aureus (30.5%), Acinetobacter baumannii (25.2%), and Klebsiella pneumoniae (24.4%). All strains of S. aureus were sensitive to vancomycin, ticoplanin, quinupristin-dalfopristin, and linezolid. Escherichia coli and Klebsiella showed high resistance to cephalosporins. More than 93% of Acinetobacter isolates were resistant to carbapenem and quinolones. The overall prevalence of ESBLs and carbapenemase producing bacteria were 80.43% and 73.6%, respectively. The most frequent ESBLs gene was blaCTX-M gene (78.3%) followed by blaAMP-C gene (67.5%), blaSHV gene (64.8%), and blaTEM gene (54%). Conclusions: In sum, there was a possibility that the treatment of nosocomial multidrug resistant infections such as VAP would become a major challenge. Therefore, it was recommended that AST results should always be considered when selecting the appropriate treatment regimen. Furthermore, it was found important to emphasize the principles of antibiotic stewardship and to constantly monitor the pattern of microbial susceptibility.

Effects of boric acid and potassium metaborate on cytokine levels and redox stress parameters in a wound model infected with methicillin‑resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infections are usually found in hospital settings and, frequently, in patients with open wounds. One of the most critical virulence factors affecting the severity and recurrence of infections is the biofilm; increasing antibiotic resistance due to biofilm formation has led to the search for alternative compounds to antibiotics. The present study aimed to use boric acid and potassium metaborate against MRSA infection in a fibroblast wound model. For this purpose, a two-part experiment was designed: First, MRSA strains were used for the test, and both boric acid and potassium metaborate were prepared in microdilution. In the second step, an MRSA wound model was prepared using a fibroblast culture, and treatments with boric acid and potassium metaborate were applied for 24 h. For the evaluation of the effects of treatment, cell viability assay (MTT assay), analysis of redox stress parameters, including total oxidant status and total antioxidant capacity analyses, lactate dehydrogenase analysis and immunohistochemical staining were performed. In addition, IL-1β and IL-10 gene expression levels were assayed. According to the results, potassium metaborate was more effective and exhibited a lower toxicity to fibroblast cells compared to boric acid; moreover, potassium metaborate decreased the level of prooxidant species and increased the antioxidant status more effectively than boric acid. The IL-1β level in the bacteria group was high; however, boric acid and potassium metaborate significantly decreased the expression levels of inflammatory markers, exhibiting the potential to improve the resolution of the lesion. On the whole, the findings of the present study suggest that boric acid and potassium metaborate may be effective on the tested microorganisms.