Identification of Methicillin-Resistant Staphylococcus Aureus From Methicillin-Sensitive Staphylococcus Aureus and Molecular Characterization in Quanzhou, China

Tackling the Antimicrobial Resistance "Pandemic" with Machine Learning Tools: A Summary of Available Evidence

Antimicrobial resistance is recognised as one of the top threats healthcare is bound to face in the future. There have been various attempts to preserve the efficacy of existing antimicrobials, develop new and efficient antimicrobials, manage infections with multi-drug resistant strains, and improve patient outcomes, resulting in a growing mass of routinely available data, including electronic health records and microbiological information that can be employed to develop individualised antimicrobial stewardship. Machine learning methods have been developed to predict antimicrobial resistance from whole-genome sequencing data, forecast medication susceptibility, recognise epidemic patterns for surveillance purposes, or propose new antibacterial treatments and accelerate scientific discovery. Unfortunately, there is an evident gap between the number of machine learning applications in science and the effective implementation of these systems. This narrative review highlights some of the outstanding opportunities that machine learning offers when applied in research related to antimicrobial resistance. In the future, machine learning tools may prove to be superbugs' kryptonite. This review aims to provide an overview of available publications to aid researchers that are looking to expand their work with new approaches and to acquaint them with the current application of machine learning techniques in this field.

Machine learning-based classification of deubiquitinase USP26 and its cell proliferation inhibition through stabilizing KLF6 in cervical cancer

OBJECTIVE

We aim to accurately distinguish ubiquitin-specific proteases (USPs) from other members within the deubiquitinating enzyme families based on protein sequences. Additionally, we seek to elucidate the specific regulatory mechanisms through which USP26 modulates Krüppel-like factor 6 (KLF6) and assess the subsequent effects of this regulation on both the proliferation and migration of cervical cancer cells.

METHODS

All the deubiquitinase (DUB) sequences were classified into USPs and non-USPs. Feature vectors, including 188D, n-gram, and 400D dimensions, were extracted from these sequences and subjected to binary classification via the Weka software. Next, thirty human USPs were also analyzed to identify conserved motifs and ascertained evolutionary relationships. Experimentally, more than 90 unique DUB-encoding plasmids were transfected into HeLa cell lines to assess alterations in KLF6 protein levels and to isolate a specific DUB involved in KLF6 regulation. Subsequent experiments utilized both wild-type (WT) USP26 overexpression and shRNA-mediated USP26 knockdown to examine changes in KLF6 protein levels. The half-life experiment was performed to assess the influence of USP26 on KLF6 protein stability. Immunoprecipitation was applied to confirm the USP26-KLF6 interaction, and ubiquitination assays to explore the role of USP26 in KLF6 deubiquitination. Additional cellular assays were conducted to evaluate the effects of USP26 on HeLa cell proliferation and migration.

RESULTS

1. Among the extracted feature vectors of 188D, 400D, and n-gram, all 12 classifiers demonstrated excellent performance. The RandomForest classifier demonstrated superior performance in this assessment. Phylogenetic analysis of 30 human USPs revealed the presence of nine unique motifs, comprising zinc finger and ubiquitin-specific protease domains. 2. Through a systematic screening of the deubiquitinase library, USP26 was identified as the sole DUB associated with KLF6. 3. USP26 positively regulated the protein level of KLF6, as evidenced by the decrease in KLF6 protein expression upon shUSP26 knockdown in both 293T and Hela cell lines. Additionally, half-life experiments demonstrated that USP26 prolonged the stability of KLF6. 4. Immunoprecipitation experiments revealed a strong interaction between USP26 and KLF6. Notably, the functional interaction domain was mapped to amino acids 285-913 of USP26, as opposed to the 1-295 region. 5. WT USP26 was found to attenuate the ubiquitination levels of KLF6. However, the mutant USP26 abrogated its deubiquitination activity. 6. Functional biological assays demonstrated that overexpression of USP26 inhibited both proliferation and migration of HeLa cells. Conversely, knockdown of USP26 was shown to promote these oncogenic properties.

CONCLUSIONS

1. At the protein sequence level, members of the USP family can be effectively differentiated from non-USP proteins. Furthermore, specific functional motifs have been identified within the sequences of human USPs. 2. The deubiquitinating enzyme USP26 has been shown to target KLF6 for deubiquitination, thereby modulating its stability. Importantly, USP26 plays a pivotal role in the modulation of proliferation and migration in cervical cancer cells.

Identification of SH2 domain-containing proteins and motifs prediction by a deep learning method

The Src Homology 2 (SH2) domain plays an important role in the signal transmission mechanism in organisms. It mediates the protein-protein interactions based on the combination between phosphotyrosine and motifs in SH2 domain. In this study, we designed a method to identify SH2 domain-containing proteins and non-SH2 domain-containing proteins through deep learning technology. Firstly, we collected SH2 and non-SH2 domain-containing protein sequences including multiple species. We built six deep learning models through DeepBIO after data preprocessing and compared their performance. Secondly, we selected the model with the strongest comprehensive ability to conduct training and test separately again, and analyze the results visually. It was found that 288-dimensional (288D) feature could effectively identify two types of proteins. Finally, motifs analysis discovered the specific motif YKIR and revealed its function in signal transduction. In summary, we successfully identified SH2 domain and non-SH2 domain proteins through deep learning method, and obtained 288D features that perform best. In addition, we found a new motif YKIR in SH2 domain, and analyzed its function which helps to further understand the signaling mechanisms within the organism.

From Hospital to Community: Exploring Antibiotic Resistance and Genes Associated with Virulence Factor Diversity of Coagulase-Positive Staphylococci

Coagulase-positive staphylococcus (CoPS), including methicillin-resistant Staphylococcus aureus (MRSA), poses a global threat. The increasing prevalence of MRSA in Saudi Arabia emphasizes the need for effective management. This study explores the prevalence of virulence-associated genes and antibiotic resistance patterns in CoPS. Nasal swabs from 200 individuals were collected, and standard protocols were used for the isolation, identification, and characterization of CoPS and coagulase-negative staphylococci (CoNS). Additionally, antimicrobial susceptibility testing and PCR were conducted. Bacterial growth was observed in 58.5% of participants, with 12% positive for CoPS and 30% positive for CoNS. Hospital personnel carriers showed a significantly higher proportion of CoNS compared with non-hospital personnel carriers. Non-hospital personnel CoPS strains displayed higher sensitivity to oxacillin than hospital personnel strains. Cefoxitin exhibited the highest sensitivity among β-lactam antibiotics. All isolates were sensitive to trimethoprim/sulfamethoxazole, rifampin, and quinupristin. Polymerase chain reaction analysis detected methicillin resistance genes in both non-hospital and hospital personnel MRSA strains. The coa and spa genes were prevalent in MRSA isolates, while the Luk-PV gene was not detected. A high prevalence of CoPS and CoNS was observed in both non-hospital and hospital personnel carriers. Occupational risk factors may contribute to the differences in the strain distribution. Varying antibiotic susceptibility patterns indicate the effectiveness of oxacillin and cefoxitin. Urgent management strategies are needed due to methicillin resistance. Further research is necessary to explore additional virulence-associated genes and develop comprehensive approaches for CoPS infection prevention and treatment in Saudi Arabia.

Progress in the Prevalence, Classification and Drug Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus is a common human pathogen with a variety of virulence factors, which can cause multiple infectious diseases. In recent decades, due to the constant evolution and the abuse of antibiotics, Staphylococcus aureus was becoming more resistant, the infection rate of MRSA remained high, and clinical treatment of MRSA became more difficult. The genetic diversity of MRSA was mainly represented by the continuous emergence of epidemic strains, resulting in the constant changes of epidemic clones. Different classes of MRSA resulted in different epidemics and resistance characteristics, which could affect the clinical symptoms and treatments. MRSA had also spread from traditional hospitals to community and livestock environments, and the new clones established a relationship between animals and humans, promoting further evolution of MRSA. Since the resistance mechanism of MRSA is very complex, it is important to clarify these resistance mechanisms at the molecular level for the treatment of infectious diseases. We firstly described the diversity of SCCmec elements, and discussed the types of SCCmec, its drug resistance mechanisms and expression regulations. Then, we described how the vanA operon makes Staphylococcus aureus resistant to vancomycin and its expression regulation. Finally, a brief introduction was given to the drug resistance mechanisms of biofilms and efflux pump systems. Analyzing the resistance mechanism of MRSA can help study new anti-infective drugs and alleviate the evolution of MRSA. At the end of the review, we summarized the treatment strategies for MRSA infection, including antibiotics, anti-biofilm agents and efflux pump inhibitors. To sum up, here we reviewed the epidemic characteristics of Staphylococcus aureus, summarized its classifications, drug resistance mechanisms of MRSA (SCCmec element, vanA operon, biofilm and active efflux pump system) and novel therapy strategies, so as to provide a theoretical basis for the treatment of MRSA infection.

Synergistic Inhibition of Methicillin-Resistant Staphylococcus aureus (MRSA) by Melaleuca alternifolia Chell (Tea Tree) and Eucalyptus globulus Labill. Essential Oils in Association with Oxacillin

The presence of antibiotic-resistant bacteria has become a major therapeutic priority. This trend indicates the need for alternative agents to antibiotics, such as natural compounds of plant origin. By assessing membrane permeability, we investigated the antimicrobial activity of Melaleuca alternifolia and Eucalyptus globulus essential oils (EOs) against three strains of methicillin-resistant Staphylococcus aureus (MRSA). Using the checkerboard method, the efficacy of single EOs, in association with each other or in combination with oxacillin, was quantified by calculating the fractional inhibitory concentrations (FIC Index). All EOs showed a reduction in bacterial load, an alteration of membrane permeability which leads to an increase in its function, resulting in the release of nucleic acids and proteins. The treatment with EO-oxacillin combinations and associated EO-EO resulted in a synergistic effect in most of the tests performed. EO-EO association showed a high activity in the alteration of the membrane, increasing the permeability to about 80% in all the MRSA strains treated. In conclusion, the combination of EOs and antibiotics represents a valid therapeutic support against MRSA bacteria, allowing for a decrease in the antibiotic concentration needed for therapeutic use.

Investigating the antibacterial mechanism of Ampelopsis cantoniensis extracts against methicillin-resistant Staphylococcus aureus via in vitro and in silico analysis

Methicillin-resistant Staphylococcus aureus (MRSA) is a critical pathogen responsible for a wide variety of serious infectious diseases in humans. The accelerated phenomena of drug tolerance, drug resistance, and dysbacteriosis provoked by antibiotic misuse are impeding the effectiveness of contemporary antibiotic therapies primarily used to treat this common worldwide pathogen. In this study, the antibacterial activity of 70% ethanol extract and multiple polar solvents of Ampelopsis cantoniensis were measured against the clinical MRSA isolate. The agar diffusion technique was employed to determine the zone of inhibition (ZOI), accompanied by the use of a microdilution series to identify the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Our results revealed that the ethyl acetate fraction exhibited the most significant antibacterial activity, which was determined to be bacteriostatic based on the MBC/MIC ratio 8. A list of compounds isolated from A. cantoniensis was computationally studied to further investigate the mechanism of action with the bacterial membrane protein PBP2a. The combination of molecular docking and molecular dynamics methods showed that the main compound, dihydromyricetin (DHM), is expected to bind to PBP2a at allosteric site. In addition, DHM was identified as the major compound of ethyl acetate fraction, which accounts for 77.03 ± 2.44% by high performance liquid chromatography (HPLC) analysis. As a concluding remark, our study addressed the antibacterial mechanism and suggested the prioritization of natural products derived from A. cantoniensis as a potential therapy for MRSA.Communicated by Ramaswamy H. Sarma.

Antimicrobial Resistance Genes Analysis of Publicly Available Staphylococcus aureus Genomes

Staphylococcus aureus is a pathogen that can cause severe illness and express resistance to multiple antimicrobial agents. It is part of the ESKAPE organisms and it has been included by the Centers for Disease Control and Prevention (CDC) of USA in the list of serious threats to humans. Many antimicrobial mechanisms have been identified, and, in particular, antimicrobial resistance genes (ARGs) can be determined by whole genome sequencing. Mobile genetic elements (MGEs) can determine the spread of these ARGs between strains and species and can be identified with bioinformatic analyses. The scope of this work was to analyse publicly available genomes of S. aureus to characterise the occurrence of ARGs present in chromosomes and plasmids in relation to their geographical distribution, isolation sources, clonal complexes, and changes over time. The results showed that from a total of 29,679 S. aureus genomes, 24,765 chromosomes containing 73 different ARGs, and 21,006 plasmidic contigs containing 47 different ARGs were identified. The most abundant ARG in chromosomes was mecA (84%), while blaZ was the most abundant in plasmidic contigs (30%), although it was also abundant in chromosomes (42%). A total of 13 clonal complexes were assigned and differences in ARGs and CC distribution were highlighted among continents. Temporal changes during the past 20 years (from 2001 to 2020) showed that, in plasmids, MRSA and macrolide resistance occurrence decreased, while the occurrence of ARGs associated with aminoglycosides resistance increased. Despite the lack of metadata information in around half of the genomes analysed, the results obtained enable an in-depth analysis of the distribution of ARGs and MGEs throughout different categories to be undertaken through the design and implementation of a relatively simple pipeline, which can be also applied in future works with other pathogens, for surveillance and screening purposes.

Molecular characterization and virulence gene profiling of methicillin-resistant Staphylococcus aureus associated with bloodstream infections in southern China

Methicillin-resistant Staphylococcus aureus (MRSA) causes an enormous illness burden, including skin and soft tissue infections (SSTIs), pneumonia, bloodstream infections (BSI), and sepsis. BSI are associated with significant patient morbidity and mortality worldwide. However, limited information is available on MRSA-related BSI in China. This study aimed to investigate the molecular characterization of 77 MRSA isolates recovered from hospitalized patients with BSI between 2012 and 2020 at three first-class tertiary hospitals in southern China based on multilocus sequence typing (MLST), spa typing, and staphylococcal cassette chromosome mec (SCCmec) typing. Overall, 13 clonal complexes (CCs) were identified, with CC59 and CC5 being the largest clusters, indicating high genetic diversity among BSI-causing MRSA isolates. ST59 was the most prevalent MLST type (22.1%). ST5/ST764-MRSA SCCmec II was the predominant adult MRSA clone, whereas ST59-MRSA SCCmec IV was the most common pediatric MRSA clone. ST5-t2460, ST764-t1084, and ST59-t437 were the most common types of adult MRSA isolates, whereas ST59-t437 and ST59-t172 were the predominant types of children’s MRSA isolates. ST59-SCCmec IV/V represented the most common clone among community acquired-MRSA isolates. ST5/ST764-SCCmec II was the most common type of hospital-associated MRSA isolate. The most prevalent toxin-encoding genes detected were hla, hld, icaA, and clfA (96.1–100%). Forty-three (100%, 43/43) isolates harbored more than 18 of the tested virulence genes in adults and eight virulence genes (23.5%, 8/34) in children. Virulence gene analysis revealed diversity among different clones: the positivity rates for the Panton-Valentine leukocidin (PVL) gene were 55.8 and 35.3% in adult and pediatric MRSA isolates, respectively; the genes seb–sei were present in all adult strains; seb–seg–sei–seo were present in all ST5, ST59, ST15, ST45, and ST22 adult strains; and seg–sei–sem–sen–seo were present in different clones, including ST15, ST45, and ST22 adult MRSA isolates and ST25, ST30, ST546, and ST72 children’s MRSA isolates. Adult MRSA isolates had significantly higher antibiotic resistance rates and virulence gene prevalence than pediatric MRSA isolates. For 8 years, this study provided epidemiological data on the molecular characteristics and virulence genes in different groups of MRSA BSI in China. Our findings may provide critical information for a better understanding of MRSA BSI.