Survey of infections due to Staphylococcus species: frequency of occurrence and antimicrobial susceptibility of isolates collected in the United States, Canada, Latin America, Europe, and the Western Pacific region for the SENTRY Antimicrobial Surveillance Program, 1997-1999

Assessment of Methicillin-Resistant Staphylococcus aureus (MRSA) knowledge and awareness among healthcare workers in South-Lebanon

Background

Methicillin-Resistant Staphylococcus aureus (MRSA) is a well-known cause of hospital acquired infections (HAIs), associated with high rates of morbidity and mortality. In healthcare settings, MRSA can spread via contaminated surfaces and direct contact.

Objective

This study aims to assess the knowledge and awareness of MRSA risks, prevention methods (such as hand hygiene), proper antibiotics use, and multidrug resistance among various groups of healthcare workers (HCWs) in Southern Lebanon.

Methods

A total of 244 HCWs, including those in medical services (MS), paramedical services (PS), and non-medical services (NMS), were conveniently selected for this study. Data was gathered using a structured, validated questionnaire that explored their knowledge and awareness of MRSA risks, prevention measures, hand hygiene practices, and multidrug resistance.

Results

The findings revealed that 68% of HCWs were aware of the origin of MRSA infection, and 61.5% and 51.6% were familiar with its treatment and transmission, respectively. Only 24.2% of HCWs were able to differentiate between hospital-acquired and community-acquired MRSA, 14.7% were aware of the institution's written MRSA control protocols, and 17.6% had heard of MRSA infections. Notably, knowledge and hand hygiene practices were significantly better among MS HCWs than PS and NMS groups (P<0.0001). While all HCWs were familiar with antibiotic usage and drug resistance, NMS HCWs were more likely to use antibiotics without a prescription compared to MS and PS groups (P<0.003).

Conclusion

HCWs in South-Lebanon demonstrated a knowledge gap regarding MRSA risks and prevention guidelines. These findings underscore the need for targeted educational intervention on MRSA, as well as coordinated efforts by healthcare authorities and centres to control MRSA infections.

Design, Characterization, and Preparation of New Smart Photoactive Polymers and Their Capacity for Photodynamic Antimicrobial Action in Organic Film

The photosensitive properties of smart photoactive polymers give them a wide range of potential applications across various fields. This study focuses on designing polymeric systems that incorporate hydrophilic polymers, with the primary goal of adapting these materials for biological applications. Specifically, it aims to contribute to the development of photochromic materials for optical processing, utilizing both molecular and macromolecular components. Additionally, this study evaluates the effectiveness of photoactive polymers in photodynamic therapy (PDT). It details the synthesis and characterization of photoactive copolymers derived from maleic anhydride (MAn) combined with vinyl monomers such as 2-methyl-2-butene (MB) and 1-octadecene (OD), as well as the organic compound 1-(2-hydroxyethyl)-3,3-dimethylindoline-6-nitrobenzopyran (SP). The two novel optically active alternating polymeric systems, poly(maleic anhydride-alt-octadecene) and poly(maleic anhydride-alt-2-methyl-2-butene), were functionalized with SP through an esterification process in a 1:1 monomer feed ratio, using pyridine as a catalyst. This methodology incorporated approximately 100% of the photoactive molecules into the main acrylic chain to prepare the alternating copolymers. These copolymers were characterized by UV-visible, FTIR, and 1H-NMR spectroscopy and analysis of their optical and thermal properties. When exposed to UV light, the photoactive polymer films can develop a deep blue color (566 nm in the absorption spectra). Finally, the study also assesses their capacity for photodynamic antimicrobial action in organic film. Notably, the photoactive P(MAn-alt-2MB)-PS significantly enhances the photodynamic antimicrobial activity of the photosensitizer Ru(bpy) against two bacterial strains of Staphylococcus aureus, reducing the minimum inhibitory concentration (MIC) from 2 µg/mL to 0.5 µg/mL. Therefore, 4 times less photosensitizer is required when mixed with the photoactive polymer to inhibit the growth of antibiotic-sensitive and -resistant bacteria.

Leveraging electronic medical records to evaluate a computerized decision support system for staphylococcus bacteremia

Infectious disease specialists (IDS) improve outcomes of patients with Staphylococcus bacteremia, but immediate IDS access is not always guaranteed. We investigated whether a care-integrated computerized decision support system (CDSS) can safely enhance the standard of care (SOC) for these patients. We conducted a multicenter, noninferiority, interventional stepped-wedge cluster randomized controlled trial relying on the data integration centers at five university hospitals. By this means, electronic medical records can be used for part of the trial documentation. We analyzed 5056 patients from 134 wards (Staphylococcus aureus (SAB): n = 812, coagulase-negative staphylococci (CoNS): n = 4244) and found that the CDSS was noninferior to the SOC for hospital mortality in all patients. Noninferiority regarding the 90-day mortality/relapse in SAB patients was not observed and there was no evidence for differences in vancomycin usage among CoNS patients. Despite low reported usage, physicians rated the CDSS's usability favorably. Trial registration: drks.de; Identifier: DRKS00014320; Registration Date: 2019-05-06.

Prevalence of MRSA in Livestock, Including Cattle, Farm Animals, and Poultry, in Mainland China, Hong Kong Special Administrative Region, Sri Lanka, and Bangladesh: A Systematic Review and Meta-Analysis

Methicillin-resistant Staphylococcus aureus (MRSA) can spread from animals to humans, but how it adapts to infect both is not fully understood. Our review aimed to determine the prevalence of MRSA in livestock, poultry, and companion animals in different countries, including Bangladesh, the Hong Kong SAR, Mainland China, and Sri Lanka. Articles were collected using PubMed, Embase, Web of Science, Scopus, CINAHL, and Google Scholar. Only prevalence studies that followed the PICO guidelines were included. A random-effects model meta-analysis was used to pool the data. The quality of the evidence and bias were assessed using the GRADEpro and Cochrane collaboration tools. Out of 1438 articles, 69 studies were eligible for meta-analysis. The studies showed significant heterogeneity (I2 = 97.00%, p < 0.0001) in the prevalence of MRSA colonization. Therefore, a random-effects model was used to determine the pooled prevalence of MRSA colonization, which was found to be 4.92% (95% CI: 3.79% to 6.18%). Begg's test (p = 0.0002) and Egger's test (p = 0.0044) revealed publication bias. Subgroup analysis of the pooled prevalence of MRSA showed a significant difference (p < 0.00001) when the subgroups were divided by country, MRSA detection method, whether pre-enrichment was performed or not, study period, sample collection location, and study population. Although significant factors can partially explain the heterogeneity, it is crucial to recognize the heterogeneity within different subgroups. The pooled prevalence of MRSA was found to vary significantly (p < 0.00001) among the study periods and has increased since the study period of 2020. Therefore, it is crucial to continuously monitor and implement measures to control the spread of MRSA in animals to minimize the risk of transmission to humans.

Managing a Rare Case of Methicillin-Resistant Staphylococcus aureus (MRSA) Holocord With Intravenous Antibiotics

Holocord pathologies are diseases that include the entire spinal cord, and, in most instances, neurological cancers are the most common cause of holocord pathologies. However, in some rare instances, there are cases in which bacterial infections can extend into deeper spaces, causing spinal epidural abscesses (SEA), holocord SEA (HSEA), or even rarer spinal subdural abscesses (SSA). Current discussions surrounding the management of HSEA, SEA, or SSA primarily involve early surgical intervention and subsequent antibiotics. However, in this case, we present a patient with methicillin-resistant Staphylococcus aureus (MRSA) holocord subdural abscess, along with epidural and paraspinal abscesses who was treated with intravenous antibiotics and no surgical intervention. A discussion regarding this rare disease, along with the treatment of MRSA holocord, is also included.

Modeling and simulation of distribution and drug resistance of major pathogens in patients with respiratory system infections

BACKGROUND

Respiratory tract infections (RTIs) are one of the leading causes of morbidity and mortality worldwide. The increase in antimicrobial resistance in respiratory pathogens poses a major challenge to the effective management of these infections.

OBJECTIVE

To investigate the distribution of major pathogens of RTIs and their antimicrobial resistance patterns in a tertiary care hospital and to develop a mathematical model to explore the relationship between pathogen distribution and antimicrobial resistance.

METHODS

Five hundred patients with RTIs were included in the study and 475 bacterial strains were isolated from their respiratory specimens. Antimicrobial susceptibility testing and analysis of influencing factors were performed. A mathematical model was developed to simulate the relationship between pathogen distribution and drug resistance.

RESULTS

The most common pathogens were Streptococcus pneumoniae (30%), Haemophilus influenzae (20%), Pseudomonas aeruginosa (15%), Staphylococcus aureus (10%) and Klebsiella pneumoniae (10%). The distribution of pathogens varied according to age group and type of RTIs, with higher proportions of Pseudomonas aeruginosa and Staphylococcus aureus in hospital-acquired and ventilator-associated pneumonia. Isolated pathogens showed high and increasing rates of resistance to commonly used antibiotics. Model simulations suggest that a shift in the distribution of pathogens toward more resistant strains may lead to a significant increase in overall resistance rates, even if antibiotic use patterns remain unchanged.

CONCLUSION

This study emphasizes the importance of regular monitoring of respiratory pathogen distribution and antimicrobial resistance patterns and the need for a comprehensive approach to managing RTIs, including implementation of antibiotic stewardship programs, infection control measures, and development of new therapies.

Supramolecular discrimination and diagnosis-guided treatment of intracellular bacteria

Pathogenic intracellular bacteria pose a significant threat to global public health due to the barriers presented by host cells hindering the timely detection of hidden bacteria and the effective delivery of therapeutic agents. To address these challenges, we propose a tandem diagnosis-guided treatment paradigm. A supramolecular sensor array is developed for simple, rapid, accurate, and high-throughput identification of intracellular bacteria. This diagnostic approach executes the significant guiding missions of screening a customized host-guest drug delivery system by disclosing the rationale behind the discrimination. We design eight azocalix[4]arenes with differential active targeting, cellular internalization, and hypoxia responsiveness to penetrate cells and interact with bacteria. Loaded with fluorescent indicators, these azocalix[4]arenes form a sensor array capable of discriminating eight intracellular bacterial species without cell lysis or separation. By fingerprinting specimens collected from bacteria-infected mice, the facilitated accurate diagnosis offers valuable guidance for selecting appropriate antibiotics. Moreover, mannose-modified azocalix[4]arene (ManAC4A) is screened as a drug carrier efficiently taken up by macrophages. Doxycycline loaded with ManAC4A exhibits improved efficacy against methicillin-resistant Staphylococcus aureus-infected peritonitis. This study introduces an emerging paradigm to intracellular bacterial diagnosis and treatment, offering broad potential in combating bacterial infectious diseases.

Pharmacodynamic Profiling of Amoxicillin: Targeting Multidrug-Resistant Gram-Positive Pathogens Staphylococcus aureus and Staphylococcus pseudintermedius in Canine Clinical Isolates

The rising threat of antimicrobial resistance (AMR) is a global concern in both human and veterinary medicine, with multidrug-resistant (MDR) pathogens such as Staphylococcus aureus and Staphylococcus pseudintermedius presenting significant challenges. Background/Objectives: This study evaluates the effectiveness of amoxicillin against these MDR pathogens in canine isolates using pharmacokinetic and pharmacodynamic parameters. Methods: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and mutation prevention concentration (MPC) were assessed. Additionally, time-kill assays and post-antibiotic effect (PAE) assessments were performed. Epidemiological cutoff (ECOFF) values were established for both species to guide therapy. Results: S. aureus had a higher resistance rate (35.89%) than S. pseudintermedius (15.27%), with MIC50 values of 0.50 μg/mL and 0.25 μg/mL, respectively. The MPC analysis revealed that S. pseudintermedius required higher antibiotic concentrations (16.11 μg/mL) to prevent mutations compared to S. aureus (2.20 μg/mL). Time-kill assays indicated that higher amoxicillin dosages caused faster bacterial reduction. The PAE analysis showed extended post-treatment bacterial suppression at elevated doses, particularly against S. aureus. Conclusions: Species-specific amoxicillin dosing strategies are necessary due to differing resistance and susceptibility profiles between S. aureus and S. pseudintermedius. High-dose amoxicillin therapy is recommended to achieve optimal therapeutic outcomes for resistant SA, while slightly adjusted dosing can manage S. pseudintermedius infections. These findings provide essential insights for veterinary antimicrobial stewardship, underscoring the need for tailored therapeutic approaches to minimize AMR development while ensuring effective infection control.

Tribulus terrestris Fruit Extract: Bioactive Compounds, ADMET Analysis, and Molecular Docking with Penicillin-Binding Protein 2a Transpeptidase of Methicillin-Resistant Staphylococcus epidermidis

Tribulus terrestris is a rich source of bioactive molecules and thrives in Mediterranean and desert climate regions worldwide. In this study, Tribulus terrestris methanolic HPLC fractions were evaluated for bioactive compounds and PBP2a transpeptidase inhibitors against methicillin-resistant Staphylococcus epidermidis (MRSE). Among the collected HPLC fractions, F02 of the methanol extract demonstrated potential activity against MRSE01 (15 ± 0.13 mm), MRSE02 (13 ± 0.21 mm), and MRSE03 (16 ± 0.14 mm) isolates. GC-MS analysis of the F02 fraction identified seventeen compounds. Among seventeen compounds, eight have favorable pharmacokinetics and medicinal chemistry; however, on the basis of in silico high water solubility, high GI absorption, blood-brain barrier non-permeability, lack of toxicity, and potential drug-likeness, 1-ethylsulfanylmethyl-2,8,9-trioxa-5-aza-1-sila-bicyclo[3.3.3]undecane and phthalimide, N-(1-hydroxy-2-propyl), were processed for molecular docking. 1-ethylsulfanylmethyl-2,8,9-trioxa-5-aza-1-sila-bicyclo[3.3.3]undecane formed three hydrogen bonds with Ser-452, Thr-584, and Asn-454 residues of the PBP2a transpeptidase. Similarly, phthalimide, N-(1-hydroxy-2-propyl)-formed four hydrogen bonds with Ser-396, Asn-454, Lys-399, and Ser-452 residues of PBP2a transpeptidase. These two compounds are proposed as novel putative PBP2a transpeptidase inhibitors. Further characterization of compounds extracted from Tribulus terrestris may aid in identifying novel PBP2a inhibitory agents for managing MRSE infections.

Risk Identification and Mitigation of Skin and Soft Tissue Infections in Military Training Environments

OBJECTIVE

Staphylococcus aureus (SA), including methicillin-resistant strains (MRSAs), is a major cause of skin and soft tissue infections (SSTIs) in military populations. This study investigated SSTI incidence and SA carriage in a military training site over 16 weeks using a prospective observational cohort design.

METHODS

Two training cohorts provided pre- and post-training self-collected swabs for bacterial carriage, and environmental swabs from accommodations, personal items, and training facilities. Hygiene awareness and practices were assessed through questionnaires. Bacteria were identified using culture, mass spectrometry (MALDI-TOF), and genomic sequencing.

RESULTS

Nasal carriage of SA increased from 19% to 49% by the end of training. SSTIs requiring treatment occurred in 16% of participants. Steam cleaning reduced but did not eliminate SA on personal bed linen. Additionally, 40% of participants had poor knowledge of antibacterial cleaning practices and wound management.

CONCLUSIONS

Increased SA carriage was linked to human-to-human transmission in close-quarter military training environments.

IMPLICATIONS FOR PUBLIC HEALTH

Improved personal hygiene training, wound management education, and monitored cleaning protocols are essential to mitigate SSTI risks in communal military training environments.

Colonisation by multidrug-resistant organisms in health workers in primary care: narrow spectrum oral antimicrobials are a risk factor

BACKGROUND

Limited information exists on carriage of multidrug-resistant organisms (MDRO) by health workers (HWs) in primary care settings. This study aims to determine the prevalence of MDRO carriage among HWs in primary care and to identify associated risk factors.

METHODS

A cross-sectional study was conducted across all 12 primary care units in São Caetano do Sul-SP, Brazil, from October to December 2023. Self-collected samples (nasal, oropharyngeal, and inguinal) were obtained. Environment cultures (potable water, sewage and stream water) were evaluated. Stenotrophomonas maltophilia isolates (human and environmental) were typed.

RESULTS

The study included 265/288 (92%) of HWs in primary care teams, mostly women with a median age of 47 years (IQR 38-57); 78% had no comorbidities. MDRO colonisation was found in 8.7% (23 HWs). The following bacteria were found: S. maltophilia (n = 9; 3.4%) in inguinal swabs; methicillin-resistant Staphylococcus aureus (n = 8; 3%) from all sites; extended-spectrum ß-lactamase-producing bacteria (n = 5; 2%) in inguinal swabs; and vancomycin-resistant enterococci in an inguinal swab (n = 1; 0.4%). Previous antibiotic use was significantly associated with MDRO colonisation (OR 2.91, 95% CI 1.19-7.09, p = 0.018), mainly narrow spectrum oral beta-lactams and macrolides. S. malthophilia was polyclonal and human and environmental isolates differed.

CONCLUSION

Colonisation by MRSA, VRE, and ESBL-producing bacteria was low; however, 4% were surprisingly colonized by polyclonal S. maltophilia. This pathogen may also suggest using narrow-spectrum rather than the expected broad-spectrum antimicrobials. Antibiotic use was the only risk factor found, mainly with oral narrow-spectrum drugs.

Antimicrobial activity of novel symmetrical antimicrobial peptides centered on a hydrophilic motif against resistant clinical isolates: in vitro and in vivo analyses

Antibiotic resistance poses a significant public health threat worldwide. The rise in antibiotic resistance and the sharp decline in effective antibiotics necessitate the development of innovative antibacterial agents. Based on the central symmetric structure of glycine-serine-glycine, combined with tryptophan and arginine, we designed a range of antimicrobial peptides (AMPs) that exhibited broad-spectrum antibacterial activity. Notably, AMP W5 demonstrated a rapid and effective sterilization against methicillin-resistant Staphylococcus aureus (MRSA), displaying both a minimum inhibitory concentration and a minimum bactericidal concentration of 8 µM. Mechanistic studies revealed that AMP W5 killed bacterial cells by disrupting the cytoplasmic membrane integrity, triggering leakage of cell contents. AMP W5 also exhibited excellent biocompatibility in both in vitro and in vivo safety evaluations. AMP W5 treatment significantly reduced skin bacterial load in our murine skin infection model. In conclusion, we designed a novel centrosymmetric AMP representing a promising medical alternative to conventional antibiotics for treating MRSA infections.

IMPORTANCE

Increasing antibiotic resistance and the paucity of effective antibiotics necessitate innovative antibacterial agents. Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen causing bacterial infections with high incidence and mortality rates, showing increasing resistance to clinical drugs. Antimicrobial peptides (AMPs) exhibit significant potential as alternatives to traditional antibiotics. This study designed a novel series of AMPs, characterized by a glycine-serine-glycine-centered symmetrical structure, and our results indicated that AMP W5 exhibited a rapid and effective bactericidal effect against MRSA. AMP W5 also demonstrated excellent biocompatibility and a bactericidal mechanism that disrupted membrane integrity, leading to leakage of cellular contents. The notable reduction in skin bacterial load observed in mouse models reinforced the clinical applicability of AMP W5. This study provides a promising solution for addressing the increasing threat of antibiotic-resistant bacteria and heralds new prospects for clinical applications.

Current types of staphylococcal cassette chromosome mec (SCCmec) in clinically relevant coagulase-negative staphylococcal (CoNS) species

Coagulase-negative staphylococci (CoNS) colonize human skin and mucosal membranes, which is why they are considered harmless commensal bacteria. Two species, Staphylococcus epidermidis and Staphylococcus haemolyticus belong to the group of CoNS species and are most frequently isolated from nosocomial infections, including device-associated healthcare-associated infections (DA-HAIs) and local or systemic body-related infections (FBRIs). Methicillin resistance, initially described in Staphylococcus aureus, has also been reported in CoNS species. It is mediated by the mecA gene within the staphylococcal cassette chromosome (SCCmec). SCCmec typing, primarily using PCR-based methods, has been employed as a molecular epidemiological tool. However, the introduction of whole genome sequencing (WGS) and next-generation sequencing (NGS) has enabled the identification and verification of new SCCmec types. This review describes the current distribution of SCCmec types, subtypes, and variants among CoNS species, including S. epidermidis, S. haemolyticus, and S. capitis. The literature review focuses on recent research articles from the past decade that discuss new combinations of SCCmec in coagulase-negative Staphylococcus. The high genetic diversity and gaps in CoNS SCCmec annotation rules underscore the need for an efficient typing system. Typing SCCmec cassettes in CoNS strains is crucial to continuously updating databases and developing a unified classification system.

Repurposing of dibucaine and niflumic acid as antimicrobial agents in combination with antibiotics against Staphylococcus aureus

The versatile human commensal bacteria and pathogen Staphylococcus aureus cause several community and hospital-acquired illnesses associated with significant morbidity and death. Antibiotic therapy for S. aureus infections has grown increasingly difficult as the organism has developed a wide spectrum of antibiotic resistance mechanisms. This situation emphasizes the significance of developing and advocating new antimicrobials for preventative and therapeutic measures. Our study aimed to identify and evaluate new therapeutic options against S. aureus. We investigated the efficacy of two drugs, dibucaine, and niflumic acid, as potential adjuvant for anti-staphylococcal therapeutics. Dibucaine and niflumic acid found to have bactericidal activity against S. aureus. These drugs acted synergistically with antibiotics reducing the required dose of antibiotics up to 4 times. In combination with antibiotics, they were effectively and synergistically inhibited the formation of biofilms of S. aureus. The best synergistic partner of dibucaine was with kanamycin and tetracycline, whereas niflumic acid was with streptomycin and ampicillin. Both the drugs showed significant efflux inhibition in the bacteria. Moreover, the drugs are found to be safe at synergistic doses. Our findings suggest that dibucaine and niflumic acid could be potential adjuvant with antibiotics for the treatment of S. aureus infections. Their ability to significantly enhance the efficacy of antibiotics highlights their potential clinical significance as adjunct therapies.

An escape from ESKAPE pathogens: A comprehensive review on current and emerging therapeutics against antibiotic resistance

The rise of antimicrobial resistance has positioned ESKAPE pathogens as a serious global health threat, primarily due to the limitations and frequent failures of current treatment options. This growing risk has spurred the scientific community to seek innovative antibiotic therapies and improved oversight strategies. This review aims to provide a comprehensive overview of the origins and resistance mechanisms of ESKAPE pathogens, while also exploring next-generation treatment strategies for these infections. In addition, it will address both traditional and novel approaches to combating antibiotic resistance, offering insights into potential new therapeutic avenues. Emerging research underscores the urgency of developing new antimicrobial agents and strategies to overcome resistance, highlighting the need for novel drug classes and combination therapies. Advances in genomic technologies and a deeper understanding of microbial pathogenesis are crucial in identifying effective treatments. Integrating precision medicine and personalized approaches could enhance therapeutic efficacy. The review also emphasizes the importance of global collaboration in surveillance and stewardship, as well as policy reforms, enhanced diagnostic tools, and public awareness initiatives, to address resistance on a worldwide scale.

A natural killer cell mimic against intracellular pathogen infections

In the competition between the pathogen infection and the host defense, infectious microorganisms may enter the host cells by evading host defense mechanisms and use the intracellular biomolecules as replication nutrient. Among them, intracellular Staphylococcus aureus relies on the host cells to protect itself from the attacks by antibiotics or immune system to achieve long-term colonization in the host, and the consequent clinical therapeutic failures and relapses after antibiotic treatment. Here, we demonstrate that intracellular S. aureus surviving well even in the presence of vancomycin can be effectively eliminated using an emerging cell-mimicking therapeutic strategy. These cell mimics with natural killer cell-like activity (NKMs) are composed of a redox-responsive degradable carrier, and perforin and granzyme B within the carrier. NKMs perform far more effectivly than clinical antibiotics in treating intracellular bacterial infections, providing a direct evidence of the NK cell-mimicking immune mechanism in the treatment of intracellular S. aureus.

Identification of novel genetic factors that regulate c-di-AMP production in Staphylococcus aureus using a riboswitch-based biosensor

Nucleotide secondary messengers regulate various processes in bacteria allowing them to rapidly respond to changes in environmental conditions. c-di-AMP is an essential second messenger required for the growth of the human pathogen Staphylococcus aureus, regulating potassium, osmolyte uptake, and beta-lactam resistance. Cellular concentrations of c-di-AMP are regulated by the activities of two enzymes, DacA and GdpP, which synthesize and hydrolyze c-di-AMP, respectively. Besides these, only a limited number of other factors are known to regulate c-di-AMP levels. Using a c-di-AMP biosensor consisting of the Bacillus subtilis c-di-AMP-binding kimA riboswitch and yfp, we were able to efficiently detect differences in cellular c-di-AMP levels in S. aureus. To identify novel factors that regulate c-di-AMP levels, we introduced the biosensor into a library of S. aureus transposon mutants. In this manner, we obtained mutants with increased c-di-AMP levels that contained insertions in gdpP coding for the c-di-AMP hydrolase and ybbR (cdaR) coding for a c-di-AMP cyclase regulator, thus validating our screen. We also identified two high c-di-AMP mutants with insertions upstream of the nrdIEF operon coding for the ribonucleotide reductase enzyme. Further analysis revealed that the insertion down-regulated nrdIEF expression, indicating that the enzyme is a negative regulator of c-di-AMP production. This negative regulation was dependent on rsh, encoding for the synthase of the endogenous GdpP inhibitor (p)ppGpp. The methods established in this work can be readily adapted for use in other bacteria to uncover genetic or environmental factors regulating c-di-AMP levels.IMPORTANCEc-di-AMP is an important secondary messenger, produced by many bacterial species including the opportunistic pathogen Staphylococcus aureus. In this bacterium, c-di-AMP controls cell wall homeostasis, cell size, and osmotic balance. In addition, it has been shown that strains with high c-di-AMP levels exhibit increased resistance to beta-lactam antibiotics. Here, we developed a biosensor-based method for the rapid detection of c-di-AMP levels in S. aureus. We utilized the biosensor in a genetic screen for the identification of novel factors that impact cellular c-di-AMP. In this manner, we identified the ribonucleotide reductase as a novel factor altering cellular c-di-AMP levels and showed that reducing its expression leads to increased cellular c-di-AMP levels. As methicillin-resistant S. aureus strains are considered as a global health threat, it is important to study processes that dictate cellular c-di-AMP levels, which are associated with antibiotic resistance.

Inhibitory effect of Bacillus velezensis 1273 strain cell-free supernatant against developing and preformed biofilms of Staphylococcus aureus and MRSA

Microbial biofilms constitute a significant virulence factor and a substantial challenge in clinical environments due to their role in promoting antimicrobial resistance and their resilience to eradication efforts. Methicillin-resistant Staphylococcus aureus (MRSA) infections substantially increase healthcare costs, extend hospitalizations, and elevate morbidity and mortality rates. Therefore, developing innovative strategies to target and eliminate these bacteria and their biofilms effectively is imperative for robust epidemiological control. In this study, we evaluated the antibacterial and antibiofilm activities of cell-free supernatant (CFS) obtained from the Bacillus velezensis 1273 strain culture. Our data showed that CFS inhibited the growth of S. aureus ATCC 29213 and MRSA (clinical strain), with greater efficacy observed against S. aureus (1:16 dilution). Furthermore, CFS showed substantial potential in reducing biofilm formation in both strains (∼30 %) at subinhibitory concentrations. Additionally, the antibacterial activity against biofilm-formed cells showed that pure CFS treatment decreased the viability of S. aureus (60 %) and MRSA (45 %) sessile cells. We further demonstrated that CFS treatment induces the production of reactive oxygen species (ROS) and damages the membranes and cell walls of the pathogen cells. Genome analysis revealed the presence of genes encoding bacteriocins and secondary metabolites with antibacterial activity in the B. velezensis 1273 genome. These findings highlight the potential of probiotic bacterial metabolites as antibiofilm and anti-multidrug-resistant pathogens.

Molecular characteristics, risk factors, and clinical outcomes of methicillin-resistant Staphylococcus aureus infections among critically ill pediatric patients in Shanghai, 2016-2021

Objective

Methicillin-resistant Staphylococcus aureus (MRSA) infection in children has been on the rise, which poses a serious threat to their health and life in China. The purpose of this study was to determine the molecular characteristics, risk factors, and clinical outcomes of MRSA infections among critically ill pediatric patients.

Methods

A retrospective case-control study was performed in the pediatric intensive care unit (PICU) of a tertiary university teaching hospital. All children infected with culture-positive S. aureus in the PICU between January 2016 and December 2021 were included. Univariate and multivariable logistic regression analyses were used to identify potential risk factors for MRSA infection and clinical outcomes of S. aureus infection. All S. aureus isolates were characterized based on antimicrobial resistance, multilocus sequence typing (MLST) and Staphylococcal protein A (spa) typing.

Results

Of 3,974 patients admitted to the PICU, 280 were diagnosed with a S. aureus infection during the 6-year study period. Among them, 43.2% (121/280) were MRSA. All MRSA isolates showed significantly higher rates of resistance to penicillin, erythromycin, clindamycin and tetracycline than MSSA strains. The MRSA strains consisted of 45 spa types and 20 sequence types (STs) (20 clonal complexes), among which the most frequently represented were ST59-t437and ST398-t034. Multivariable logistic regression revealed vaginal delivery, respiratory failure, co-infection with a virus, C-reactive protein (CRP) > 8 mg/L as significant risk factors for MRSA infection. There was no significant difference in all-cause mortality during hospitalization between the MRSA group and the MSSA group. Furthermore, independent predictors for mortality in patients with S. aureus infections were the presence of hypoproteinemia, hematopathy, septic shock, respiratory failure, fever, and white blood cell (WBC) > 15.0 × 109/L.

Conclusions

The study revealed a high proportion of MRSA infections among critically ill pediatric patients, and found significant risk factors for MRSA infection and poor prognosis of S. aureus infection. Methicillin resistance did not contribute to the mortality in the current study. These findings will provide evidence-based practices to make the strategies of prevention and rational use of antibiotics for pediatric patients with S. aureus infection in the ICU.

Hygiene practices and antibiotic resistance among dental and medical students: a comparative study

PURPOSE

Healthcare students' hand and smartphone hygiene is critical due to potential pathogenic and antibiotic-resistant bacteria transmission. This study evaluates hygiene practices in medical and dental students at Kuwait University, exploring antibiotic resistance gene prevalence.

METHODS

Swab samples were collected from the hands and smartphones of 32 medical and 30 dental students. These samples were cultured on Columbia Blood Agar and McConkey Agar plates to quantify bacterial colony-forming units (CFUs). The extracted DNA from these colonies underwent RT-PCR to identify antibiotic resistance genes, including tem-1, shv, blaZ, and mecA. Additionally, a questionnaire addressing hygiene practices was distributed post-sample collection.

RESULTS

Medical students exhibited more frequent hand hygiene compared to dental students (P ≤ 0.0001). Although significantly fewer bacterial CFUs were found on medical students' smartphones (mean = 35 ± 53) than dental students' (mean = 89 ± 129) (P ≤ 0.05), no significant differences were observed in CFU counts on their hands (medical: mean = 17 ± 37; dental: mean = 96 ± 229). Detection of at least one of the targeted antibiotic resistance genes on medical (89% hands, 52% smartphones) and dental students' (79% hands, 63% smartphones) was not statistically significant. However, the prevalence of two genes, tem-1 and shv, was significantly higher on medical students' hands (78% and 65%, respectively) than on dental students' hands (32% and 28%, respectively).

CONCLUSION

Clinically significant prevalence of antibiotic resistance genes were found on medical and dental students' hands and smartphones, emphasizing the importance of ongoing education regarding hand hygiene and smartphone disinfection. This continuous reinforcement in the curriculum is crucial to minimizing the risk of cross-contamination.

Antimicrobial Susceptibility Profile of Methicillin-Resistant Staphylococcus Aureus Isolated from Clinical Samples at Bac Ninh Provincial General Hospital, Vietnam

Purpose

Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA) strain, can become resistant to all classes of clinically available antibiotics and causes skin infections and severe infections in the lungs, heart, and bloodstream. The study aimed to evaluate antimicrobial susceptibility patterns and MRSA exhibiting multidrug resistance obtained through a microbiological culture of clinical specimens at Bac Ninh Provincial General Hospital in Bac Ninh Province, Vietnam.

Methods

We employed a cross-sectional analysis at Bac Ninh Provincial General Hospital in Vietnam. 15,232 clinical samples from inpatients were examined. S. aureus isolates were identified using established protocols and tested for MRSA and antibiotic susceptibility. Data was analyzed using R software, with statistical calculations to assess associations between variables.

Results

Staphylococcus aureus was isolated from 417 samples (2.7%), with 77.2% being MRSA and 22.8% methicillin-susceptible Staphylococcus aureus (MSSA). Significant sources of MRSA were wounds (64.6%) and the surgical unit (50%) according to sample types and hospital wards, respectively. S. aureus showed high resistance rates, the highest being azithromycin (83.2%), and was fully susceptible to vancomycin. Among 294 multidrug-resistant (MDR) strains, the prevalence was 82.0% in MRSA and 18.0% in MSSA.

Conclusion

The study highlights widespread antimicrobial resistance among MRSA isolates from a provincial hospital in Vietnam, emphasizing the urgent need for antibiotic surveillance, formulation of antibiotic policies, and preventive measures to tackle the increasing prevalence of multidrug-resistant MRSA.

Antimicrobial Resistance of Staphylococcus spp. from Human Specimens Submitted to Diagnostic Laboratories in South Africa, 2012-2017

Antimicrobial resistance (AMR) poses a significant worldwide health challenge associated with prolonged illnesses, increased healthcare costs, and high mortality rates. The present study examined the patterns and predictors of AMR among human Staphylococcus isolates obtained from diagnostic laboratories in South Africa between 2012 and 2017. This study examined data from 404 217 isolates, assessing resistance rates across different characteristics such as age, sample origin, Staphylococcus species, and study period. The highest resistance was observed against cloxacillin (70.3%), while the lowest resistance was against Colistin (0.1%). A significant (p < 0.05) decreasing trend in AMR was observed over the study period, while a significant increasing temporal trend (p < 0.05) was observed for multidrug resistance (MDR) over the same period. A significant (p < 0.05) association was observed between specimen type, species of organism, and year of isolation with AMR outcome. Significant (p < 0.05) associations were observed between specimen type and season with MDR. The observed high levels of AMR and a growing trend in MDR are concerning for public health. Clinicians should take these findings into account when deciding on therapeutic options. Continued monitoring of AMR among Staphylococcus spp. and judicious use of antimicrobials in human medicine should be promoted.

Nanoarchitectonics of in Situ Antibiotic-Releasing Acicular Nanozymes for Targeting and Inducing Cuproptosis-like Death to Eliminate Drug-Resistant Bacteria

A series of progress has been made in the field of antimicrobial use of nanozymes due to their superior stability and decreased susceptibility to drug resistance. However, catalytically generated reactive oxygen species (ROS) are insufficient for coping with multidrug-resistant organisms (MDROs) in complex wound environments due to their low targeting ability and insufficient catalytic activity. To address this problem, chemically stable copper-gallic acid-vancomycin (CuGA-VAN) nanoneedles were successfully constructed by a simple approach for targeting bacteria; these nanoneedles exhibit OXD-like and GSH-px-like dual enzyme activities to produce ROS and induce bacterial cuproptosis-like death, thereby eliminating MDRO infections. The results of in vitro experiments showed that the free carboxylic acid of GA could react with the free ammonia of teichoic acid in the methicillin-resistant Staphylococcus aureus (MRSA) cell wall skeleton. Thus, CuGA-VAN nanoneedles can rapidly "capture" MRSA in liquid environments, releasing ROS, VAN and Cu2+ on bacterial surfaces to break down the MRSA barrier, destroying the biofilm. In addition, CuGA-VAN effectively promoted wound repair cell proliferation and angiogenesis to facilitate wound healing while ensuring biosafety. According to transcriptome sequencing, highly internalized Cu2+ causes copper overload toxicity; downregulates genes related to the bacterial glyoxylate cycle, tricarboxylic acid cycle, and oxidative respiratory chain; and induces lipid peroxidation in the cytoplasm, leading to bacterial cuproptosis-like death. In this study, CuGA-VAN was cleverly designed to trigger a cascade reaction of targeting, drug release, ROS-catalyzed antibacterial activity and cuproptosis-like death. This provides an innovative idea for multidrug-resistant infections.

Microbial mysteries: Staphylococcus aureus and the enigma of carcinogenesis

Staphylococcus aureus, a common human pathogen, has long been the focus of scientific investigation due to its association with various infections. However, recent research has unveiled a tantalizing enigma surrounding this bacterium and its potential involvement in carcinogenesis. Chronic S. aureus infections have been linked to an elevated risk of certain cancers, including skin cancer and oral cancer. This review explores the current state of knowledge regarding this connection, examining epidemiological evidence, pathogenic mechanisms, and biological interactions that suggest a correlation. Although initial studies point to a possible link, the precise mechanisms through which S. aureus may contribute to cancer development remain elusive. Emerging evidence suggests that the chronic inflammation induced by persistent S. aureus infections may create a tumor-promoting environment. This inflammation can lead to DNA damage, disrupt cellular signaling pathways, and generate an immunosuppressive microenvironment conducive to cancer progression. Additionally, S. aureus produces a variety of toxins and metabolites that can directly interact with host cells, potentially inducing oncogenic transformations. Despite these insights, significant gaps remain in our understanding of the exact biological processes involved. This review emphasizes the urgent need for more comprehensive research to clarify these microbiological mysteries. Understanding the role of S. aureus in cancer development could lead to novel strategies for cancer prevention and treatment, potentially transforming therapeutic approaches.

Recent developments in preventing catheter-related infections based on biofilms: A comprehensive review

Urinary and vascular catheters are among the most commonly used medical devices. However, infections caused by biofilm formation on the surface of catheters are a major cause of healthcare-associated infections. Traditional methods, such as using antimicrobials to prevent such infections, generally have short-term effects, and treatment is challenging owing to the emergence of antimicrobial-resistant bacteria. This review aims to evaluate the limitations of conventional catheter-related infection prevention efficacy, such as currently used antimicrobials, and analyze the efficacy and limitations of potential alternatives to prevent catheter-related infections that have not yet been commercialized, classified by the transition stages of biofilm formation. We intend to provide profound insights into the ideal technologies for preventing catheter-associated tract infections and present perspectives on future directions in this field.

Dynamical analysis of methicillin-resistant Staphylococcus aureus infection in North Cyprus with optimal control: prevalence and awareness

The number of Methicillin-resistant Staphylococcus aureus (MRSA) cases in communities and hospitals is on the rise worldwide. In this work, a nonlinear deterministic model for the dynamics of MRSA infection in society was developed to visualize the significance of awareness in interventions that could be applied in the prevention of transmission with and without optimal control. Positivity and uniqueness were verified for the proposed corruption model to identify the level of resolution of infection factors in society. Furthermore, how various parameters affect the reproductive number R 0 and sensitivity analysis of the proposed model was explored through mathematical techniques and figures. The global stability of model equilibria analysis was established by using Lyapunov functions with the first derivative test. A total of seven years of data gathered from a private hospital consisting of inpatients and outpatients of MRSA were used in this model for numerical simulations and for observing the dynamics of infection by using a non-standard finite difference (NSFD) scheme. When optimal control was applied as a second model, it was determined that increasing awareness of hand hygiene and wearing a mask were the key controlling measures to prevent the spread of community-acquired MRSA (CA-MRSA) and hospital-acquired MRSA (HA-MRSA). Lastly, it was concluded that both CA-MRSA and HA-MRSA cases are on the rise in the community, and increasing awareness concerning transmission is extremely significant in preventing further spread.

Developing phytocompound-based new drugs against multi-drug-resistant Staphylococcus aureus

Staphylococcus aureus, a prevalent component of the human microbiota, is associated with skin infections to life-threatening diseases, presenting challenges in treatment options and necessitating the development of effective treatments. This study integrated computational and in vitro approaches to identify promising phytocompounds with therapeutic potential. Staphopain B emerged as a target protein for its role in immune evasion, exhibiting stability during molecular dynamic simulation (MDS) with a root mean square deviation value of 2.376 Å. Screening 115 phytocompounds with antibacterial properties from the PubChem database identified 12 with drug-like properties, nine of which showed superior binding affinity to Staphopain B compared to a commercial antibiotic, doxycycline (-7.8 kcal mol-1). Notably, epoxyazadiradione and nimbolide displayed higher estimated free energy of binding scores (-7.91 and -7.93 kcal mol-1, respectively), indicating strong protein-ligand interactions. The root mean square fluctuation values for epoxyazadiradione and nimbolide were 1.097 and 1.034 Å, respectively, which was confirmed through MDS. Crude ethanolic extracts (100% and 70%) of neem (Azadirachta indica) leaves demonstrated narrow inhibition against the bacteria in comparison to doxycycline in the disc-diffusion assay. This study underscores the potential of phytocompounds as therapeutic agents against S. aureus; however, further in vitro experiments and testing of the phytocompounds in vivo are required.

A New Theranostic Platform Against Gram-Positive Bacteria Based on Near-Infrared-Emissive Aggregation-Induced Emission Nanoparticles

Infections induced by Gram-positive bacteria pose a great threat to public health. Antibiotic therapy, as the first chosen strategy against Gram-positive bacteria, is inevitably associated with antibiotic resistance selection. Novel therapeutic strategies for the discrimination and inactivation of Gram-positive bacteria are thus needed. Here, a specific type of aggregation-induced emission luminogen (AIEgen) with near-infrared fluorescence emission as a novel antibiotic-free therapeutic strategy against Gram-positive bacteria is proposed. With the combination of a positively charged group into a highly twisted architecture, self-assembled AIEgens (AIE nanoparticles (NPs)) at a relatively low concentration (5 µm) exhibited specific binding and photothermal effect against living Gram-positive bacteria both in vitro and in vivo. Moreover, toxicity assays demonstrated excellent biocompatibility of AIE NPs at this concentration. All these properties make the AIE NPs as a novel generation of theranostic platform for combating Gram-positive bacteria and highlight their promising potential for in vivo tracing of such bacteria.

Rapid identification and subsequent contextualization of an outbreak of methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit using nanopore sequencing

Outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) are well described in the neonatal intensive care unit (NICU) setting. Genomics has revolutionized the investigation of such outbreaks; however, to date, this has largely been completed retrospectively and has typically relied on short-read platforms. In 2022, our laboratory established a prospective genomic surveillance system using Oxford Nanopore Technologies sequencing for rapid outbreak detection. Herein, using this system, we describe the detection and control of an outbreak of sequence-type (ST)97 MRSA in our NICU. The outbreak was identified 13 days after the first MRSA-positive culture and at a point where there were only two known cases. Ward screening rapidly defined the extent of the outbreak, with six other infants found to be colonized. There was minimal transmission once the outbreak had been detected and appropriate infection control measures had been instituted; only two further ST97 cases were detected, along with three unrelated non-ST97 MRSA cases. To contextualize the outbreak, core-genome single-nucleotide variants were identified for phylogenetic analysis after de novo assembly of nanopore data. Comparisons with global (n=45) and national surveillance (n=35) ST97 genomes revealed the stepwise evolution of methicillin resistance within this ST97 subset. A distinct cluster comprising nine of the ten ST97-IVa genomes from the NICU was identified, with strains from 2020 to 2022 national surveillance serving as outgroups to this cluster. One ST97-IVa genome presumed to be part of the outbreak formed an outgroup and was retrospectively excluded. A second phylogeny was created using Illumina sequencing, which considerably reduced the branch lengths of the NICU isolates on the phylogenetic tree. However, the overall tree topology and conclusions were unchanged, with the exception of the NICU outbreak cluster, where differences in branch lengths were observed. This analysis demonstrated the ability of a nanopore-only prospective genomic surveillance system to rapidly identify and contextualize an outbreak of MRSA in a NICU.

Comprehensive genomic landscape of antibiotic resistance in Staphylococcus epidermidis

Staphylococcus epidermidis, a common commensal bacterium found on human skin, can cause infections in clinical settings, and the presence of antibiotic resistance genes (ARGs) impedes the treatment of S. epidermidis infections. However, studies characterizing the ARGs in S. epidermidis with regard to genomic and ecological diversities are limited. Thus, we performed a comprehensive and comparative analysis of 405 high-quality S. epidermidis genomes, including those of 35 environmental isolates from the Han River, to investigate the genomic diversity of antibiotic resistance in this pathogen. Comparative genomic analysis revealed the prevalence of ARGs in S. epidermidis genomes associated with multi-locus sequence types. The genes encoding dihydrofolate reductase (dfrC) and multidrug efflux pump (norA) were genome-wide core ARGs. β-Lactam class ARGs were also highly prevalent in the S. epidermidis genomes, which was consistent with the resistance phenotype observed in river isolates. Furthermore, we identified chloramphenicol acetyltransferase genes (cat) in the plasmid-like sequences of the six river isolates, which have not been reported previously in S. epidermidis genomes. These genes were identical to those harbored by the Enterococcus faecium plasmids and associated with the insertion sequence 6 family transposases, homologous to those found in Staphylococcus aureus plasmids, suggesting the possibility of horizontal gene transfer between these Gram-positive pathogens. Comparison of the ARG and virulence factor profiles between S. epidermidis and S. aureus genomes revealed that these two species were clearly distinguished, suggesting genomic demarcation despite ecological overlap. Our findings provide a comprehensive understanding of the genomic diversity of antibiotic resistance in S. epidermidis.

IMPORTANCE

A comprehensive understanding of the antibiotic resistance gene (ARG) profiles of the skin commensal bacterium and opportunistic pathogen Staphylococcus epidermidis needs to be documented from a genomic point of view. Our study encompasses a comparative analysis of entire S. epidermidis genomes from various habitats, including those of 35 environmental isolates from the Han River sequenced in this study. Our results shed light on the distribution and diversity of ARGs within different S. epidermidis multi-locus sequence types, providing valuable insights into the ecological and genetic factors associated with antibiotic resistance. A comparison between S. epidermidis and Staphylococcus aureus revealed marked differences in ARG and virulence factor profiles, despite their overlapping ecological niches.

Clinical Impact of Vancomycin MIC on Outcomes in Patients With Coagulase-negative Staphylococcal Bacteremia

PURPOSE

Coagulase-negative staphylococci (CoNS) are Gram-positive organisms that are a known component of normal skin flora and the most common cause of nosocomial bacteremia. For CoNS species, the vancomycin MIC breakpoint for susceptibility set by the Clinical and Laboratory Standards Institute is ≤4 µg/mL. There has been published reports of vancomycin heteroresistance in CoNS with vancomycin MICs of 2 to 4 µg/mL. The aim of this retrospective cohort analysis was to assess the clinical impact of vancomycin MICs <2 µg/mL versus ≥2 µg/mL in adult patients with CoNS bloodstream infections.

METHODS

Adult patients admitted to University Medical Center New Orleans with a blood culture positive for CoNS were assessed. The primary outcome was difference in 30-day mortality. Secondary outcomes were in-hospital, all-cause mortality; duration of bacteremia; hospital length of stay; and percentage of oxacillin-resistant CoNS.

FINDINGS

There was no difference in mortality in the vancomycin MIC <2 µg/mL group versus the vancomycin MIC ≥2 µg/mL group at 30 days (15.4% vs 17.4%; P = 1). In-hospital, all-cause mortality was also not different between groups (11.5% vs 13%; P = 1). Hospital length of stay between groups was 28.2 days versus 21 days (P = 0.692). Median duration of bacteremia was 1 day in both groups (P = 0.975), and median scheduled duration of antibiotic therapy was 14.9 days and 19.5 days (P = 0.385). The source and mode of acquisition of CoNS were similar between groups. Of all CoNS isolates, 58.7% (44 of 75) were oxacillin resistant. Staphylococcus epidermidis was the most common CoNS species at 66.7% (50 of 75). Of all isolates, 30.7% (23 of 75) had a vancomycin MIC ≥2 µg/mL, and 87% (20 of 23) of these were S. epidermidis. There was a higher percentage of S. epidermidis in the vancomycin MIC ≥2 µg/mL group than in the MIC <2 µg/mL group (87% vs 57.7%; P = 0.012). CoNS with a vancomycin MIC ≥2 µg/mL were also more likely to be oxacillin resistant (78.3% vs 50%; P = 0.005).

IMPLICATIONS

There was no difference in clinical outcomes in adult patients with a CoNS bloodstream infection with a vancomycin MIC <2 µg/mL versus ≥2 µg/mL. At present, vancomycin remains appropriate empiric therapy for CoNS bloodstream infection. Further research is needed to determine if there is a true clinical impact of a vancomycin MIC ≥2 µg/mL in CoNS infections.

Manuka honey as a non-antibiotic alternative against Staphylococcus spp. and their small colony variant (SCVs) phenotypes

The antibiotic resistance (ABR) crisis is an urgent global health priority. Staphylococci are among the problematic bacteria contributing to this emergency owing to their recalcitrance to many clinically important antibiotics. Staphylococcal pathogenesis is further complicated by the presence of small colony variants (SCVs), a bacterial subpopulation displaying atypical characteristics including retarded growth, prolific biofilm formation, heightened antibiotic tolerance, and enhanced intracellular persistence. These capabilities severely impede current chemotherapeutics, resulting in chronic infections, poor patient outcomes, and significant economic burden. Tackling ABR requires alternative measures beyond the conventional options that have dominated treatment regimens over the past 8 decades. Non-antibiotic therapies are gaining interest in this arena, including the use of honey, which despite having ancient therapeutic roots has now been reimagined as an alternative treatment beyond just traditional topical use, to include the treatment of an array of difficult-to-treat staphylococcal infections. This literature review focused on Manuka honey (MH) and its efficacy as an anti-staphylococcal treatment. We summarized the studies that have used this product and the technologies employed to study the antibacterial mechanisms that render MH a suitable agent for the management of problematic staphylococcal infections, including those involving staphylococcal SCVs. We also discussed the status of staphylococcal resistance development to MH and other factors that may impact its efficacy as an alternative therapy to help combat ABR.

In silico and structural investigation of sulfonamides targeting VraSR two component system in methicillin-resistant Staphylococcus aureus

Drug-resistant Staphylococcus aureus strains are global health concerns. Several studies have shown that these strains can develop defences against cell wall antibiotics such as β-lactams, glycopeptides and daptomycin which target cell wall biosynthesis. The coordination of these responses have been associated with two component system (TCS) regulated by histidine kinase protein (VraS) and its cognate regulator VraR which influences the target DNA upon signal recognition. Computer-based screening methods, predictions and simulations have emerged as more efficient and quick ways to identify promising new compound leads from large databases against emerging drug targets thus allowing prediction of small select set of molecules for further validations. These combined approaches conserve valuable time and resources. Due to methicillin resistance, sulfonamide-derivative medications have been found to be effective treatment strategy to treat S. aureus infections. The current study used ligand-based virtual screening (LBVS) to identify powerful sulfonamide derivative inhibitors from an antibacterial compound library against VraSR signaling components, VraS and VraR. We identified promising sulfonamide derivative [compound 5: (4-[(1-{[(3,5-Dimethoxyphenyl)Carbamoyl]Methyl}-2,4-Dioxo-1,2,3,4-Tetrahydroquinazolin-3-Yl)Methyl]-N-[(Furan-2-Yl)Methyl]Benzamide)] with reasonable binding parameters of -31.38 kJ/mol and ΔGbind score of -294.32 kJ/mol against ATP binding domain of sensor kinase VraS. We further identified four compounds N1 (PCID83276726), N3 (PCID83276757), N9 (PCID3672584), and N10 (PCID20900589) against VraR DNA binding domain (VraRC) with ΔGbind energies of -190.27, -237.54, -165.21, and -190.88 kJ/mol, respectively. Structural and simulation analyses further suggest their stable interactions with DNA interacting residues and potential to disrupt DNA binding domain dimerization; therefore, it is prudent to further investigate and characterize them as VraR dimer disruptors and inhibit other promoter binding site. Interestingly, the discovery of drugs that target VraS and VraR may open new therapeutic avenues for drug-resistant S. aureus. These predictions based on screening, simulations and binding affinities against VraSR components hold promise for opening novel therapeutic avenues against drug-resistant S. aureus and present opportunities for repositioning efforts. These efforts aim to create analogs with enhanced potency and selectivity against two-component signaling systems that significantly contribute to virulence in MRSA or VRSA. These analyses contribute valuable insights into potential avenues for combating antibiotic-resistant S. aureus through computationally driven drug discovery strategies.

Activated mesenchymal stem cells increase drug susceptibility of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa

Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa are major causes of hospital-acquired infections and sepsis. Due to increasing antibiotic resistance, new treatments are needed. Mesenchymal stem cells (MSCs) have antimicrobial effects, which can be enhanced by preconditioning with antibiotics. This study investigated using antibiotics to strengthen MSCs against MRSA and P. aeruginosa. MSCs were preconditioned with linezolid, vancomycin, meropenem, or cephalosporin. Optimal antibiotic concentrations were determined by assessing MSC survival. Antimicrobial effects were measured by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antimicrobial peptide (AMP) gene expression. Optimal antibiotic concentrations for preconditioning MSCs without reducing viability were 1 μg/mL for linezolid, meropenem, and cephalosporin and 2 μg/mL for vancomycin. In MIC assays, MSCs preconditioned with linezolid, vancomycin, meropenem, or cephalosporin inhibited MRSA or P. aeruginosa growth at lower concentrations than non-preconditioned MSCs (p ≤ 0.001). In MBC assays, preconditioned MSCs showed enhanced bacterial clearance compared to non-preconditioned MSCs, especially when linezolid and vancomycin were used against MRSA (p ≤ 0.05). Preconditioned MSCs showed increased expression of genes encoding the antimicrobial peptide genes hepcidin and LL-37 compared to non-preconditioned MSCs. The highest hepcidin expression was seen with linezolid and vancomycin preconditioning (p ≤ 0.001). The highest LL-37 expression was with linezolid preconditioning (p ≤ 0.001). MSCs' preconditioning with linezolid, vancomycin, meropenem, or cephalosporin at optimal concentrations enhances their antimicrobial effects against MRSA and P. aeruginosa without compromising viability. This suggests preconditioned MSCs could be an effective adjuvant treatment for antibiotic-resistant infections. The mechanism may involve upregulation of AMP genes.

Daptomycin and Ceftaroline Combination Therapy in Complicated Endovascular Infections Caused by Methicillin-Resistant Staphylococcus epidermidis

Background In complicated endovascular infections by methicillin-resistant Staphylococcus aureus (MRSA) or Staphylococcus epidermidis (MRSE), when first-line therapy with vancomycin (VAN) or daptomycin (DAP) fails, combination therapy with ceftaroline (CFT) and DAP has been shown to be a useful approach as salvage therapy for persistent MRSA bacteremia. Objectives This study aimed to describe experience with daptomycin and ceftaroline combination therapy in MRSE-complicated endovascular infections. Methods A single-center retrospective review of consecutive patients with MRSE-complicated endovascular infections treated with ≥72 hours of DAP+CFT at any time during the course of treatment, from January 1, 2016 to December 31, 2020, at Centro Hospitalar Universitário São João (CHUSJ), Porto, Portugal, was conducted. The exclusion criteria were known resistance to daptomycin or ceftaroline, total time of combination therapy <72 hours and loss to follow-up. Results We identified seven cases that matched our criteria: five endocarditis and two central venous catheter infections. Six patients switched to combination therapy due to treatment failure with first-line agents - three due to persistent bacteremia and three due to progression of infection despite negative blood cultures. Effective surgical source control took one to four weeks to occur. Three patients died during the treatment, one from progression of the disease and two due to another infection. Conclusions We consider the DAP+CFT combination therapy to be a valid and safe therapeutic choice in complicated patients, such as those with severe infection, poor functional status, and impossibility or delay of surgical source control. However, conclusions on the role of combination therapy should be careful due to the low number of patients and the several confounding factors.

Community-acquired Staphylococcus aureus skin and soft tissue infection risk assessment using hotspot analysis and risk maps: the case of California emergency departments

BACKGROUND

Community-acquired Staphylococcus aureus (CA-Sa) skin and soft tissue infections (SSTIs) are historically associated with densely populated urban areas experiencing high poverty rates, intravenous drug use, and homelessness. However, the epidemiology of CA-Sa SSTIs in the United States has been poorly understood since the plateau of the Community-acquired Methicillin-resistant Staphylococcus aureus epidemic in 2010. This study examines the spatial variation of CA-Sa SSTIs in a large, geographically heterogeneous population and identifies neighborhood characteristics associated with increased infection risk.

METHODS

Using a unique neighborhood boundary, California Medical Service Study Areas, a hotspot analysis, and estimates of neighborhood infection risk ratios were conducted for all CA-Sa SSTIs presented in non-Federal California emergency departments between 2016 and 2019. A Bayesian Poisson regression model evaluated the association between neighborhood-level infection risk and population structure, neighborhood poverty rates, and being a healthcare shortage area.

RESULTS

Emergency departments in more rural and mountainous parts of California experienced a higher burden of CA-Sa SSTIs between 2016 and 2019. Neighborhoods with high infection rates were more likely to have a high percentage of adults living below the federal poverty level and be a designated healthcare shortage area. Measures of population structure were not associated with infection risk in California neighborhoods.

CONCLUSIONS

Our results highlight a potential change in the epidemiology of CA-Sa SSTIs in California emergency departments. Future studies should investigate the CA-Sa burden in other geographies to identify whether this shift in epidemiology holds across other states and populations. Further, a more thorough evaluation of potential mechanisms for the clustering of infections seen across California neighborhoods is needed.

Toxocara canis-induced changes in host intestinal microbial communities

BACKGROUND

Toxocara canis is a roundworm that resides in the gastrointestinal tract of dogs and causes various pathological changes. The dog's intestinal system consists of a diverse and dynamic bacterial community that has extensive effects on intestinal physiology, immunity and metabolics. In the case of intestinal parasites, interactions with the host intestinal flora are inevitable during the process of parasitism.

METHODS

We studied the role of T. canis in regulating the composition and diversity of the intestinal flora of the host by high-throughput sequencing of the 16S ribosomal RNA gene and various bioinformatics analyses.

RESULTS

The α-diversity analysis showed that Toxocara canis infection resulted in a significant decrease in the abundance and diversity of host intestinal flora. The β-diversity analysis showed that the intestinal flora of infected dogs was similar to that carried by T. canis. Analysis of the microflora composition and differences at the phylum level showed that the ratio of Firmicutes to Bacteroidetes (F/B ratio) increased with T. canis infection. Analysis of species composition and differences at the genus level revealed that the proportion of some of the pathogenic bacteria, such as Clostridium sensu stricto and Staphylococcus, increased after T. canis infection.

CONCLUSIONS

Toxocara canis infection affected the composition and diversity of the flora in the host intestinal tract. These results not only shed light on the potential mechanism of T. canis invasion and long-term survival in the intestinal tract, but also provide a new basis for the development of anthelmintic drugs.

In silico analysis of a novel hypothetical protein (YP_498675.1) from Staphylococcus aureus unravels the protein of tryptophan synthase beta superfamily (Try-synth-beta_ II)

BACKGROUND

Staphylococcus aureus is a gram-positive spherical bacteria and the most common cause of nosocomial infections in the world. Given its clinical significance, the genome sequence of S. aureus has been elucidated to enhance our comprehension of its lifestyle and pathogenicity. The research aimed to summarize a potential hypothetical protein that may play an important role in S. aureus virulence and pathogenicity, covering its anticipated structure, probable biological functions, and importance in this context.

RESULTS

A hypothetical protein, YP_498675.1 with 281 amino acid residues of S. aureus, was chosen for analysis and modeling by several bioinformatics tools and databases in this work. According to primary and secondary structure analyses, YP_498675.1 is a stable hydrophilic protein with a significant proportion of α-helices. Subcellular localization predictions by CELLO, PSORTb, and SOSUI server indicate that it is a cytoplasmic protein. NCBI-CDD, Pfam, and InterProScan functional genomics research revealed that the hypothetical protein may include the pyridoxal phosphate (PLP)-dependent 2, 3-diaminopropionate biosynthesis protein SbnA domain. In the homology modeling method, the HHpred server was employed to create its 3D structure using the template structure of a Staphyloferrin B precursor biosynthetic enzyme SbnA bound to PLP (PDB ID: 5D84_A), an X-ray diffraction model having 100% sequence identity with the hypothetical protein. After energy minimization, several quality assessments and validation factors determined that the generated protein model was reliable and of reasonable quality.

CONCLUSION

The present study has characterized and functionally annotated the hypothetical protein YP_498675.1 of S. aureus. Further experimental validation would aid in determining the actual function of YP_498675.1 as well as confirm the protein's value as a therapeutic target.

Population structure of community-acquired extended-spectrum beta-lactamase producing Escherichia coli and methicillin resistant Staphylococcus aureus in a French region showed no difference between urban and rural areas

Antimicrobial resistance is a global health issue and extended-spectrum β-lactamase producing Escherichia coli (ESBL-Ec) and methicillin-resistant Staphylococcus aureus (MRSA) are of particular concern. Whole genome sequencing analysis of isolates from the community is essential to understand the circulation of those multidrug-resistant bacteria. Our main objective was to determine the population structure of clinical ESBL-Ec and MRSA isolated in the community setting of a French region. For this purpose, isolates were collected from 23 sites belonging to 6 private medical biology laboratories in the Bourgogne-Franche-Comté region. One hundred ninety ESBL-Ec and 67 MRSA were sequenced using the Illumina technology. Genomic analyses were performed to determine the bacterial typing, presence of antibiotic resistance genes, metal resistance genes as well as virulence genes. Analysis showed that ST131 was the major ESBL-Ec clone circulating in the region, representing 42.1% of the ESBL-Ec isolates. The blaCTX-M genes represented 98% of blaESBL with the majority being blaCTX-M-15 (53.9%). MRSA population consisted of mainly of CC8 (50.7%) and CC5 (38.8%) clonal complexes. Interestingly, we found a prevalence of 40% of the zinc resistance gene czrC in our MRSA population. We observed no differences in our ESBL-Ec or MRSA populations between urban and rural areas in our French region, suggesting no impact of population density or rural environment.

Nasal decolonization: What antimicrobials and antiseptics are most effective before surgery and in the ICU

BACKGROUND

Staphylococcus aureus colonization is a key risk factor for S. aureus infections in surgical patients and in hospitalized patients. Many studies have assessed various decolonization agents, protocols, and settings. This review summarizes key findings about nasal decolonization for 2 different patient populations: patients undergoing surgery and patients hospitalized in intensive care units.

METHODS

We reviewed major studies related to decolonization of patients colonized with S. aureus and who were either undergoing surgical procedures or were hospitalized in intensive care units. We focused on recent studies, particularly randomized controlled trials and robust quasi-experimental trials. We also reviewed select non-randomized trials when more rigorous trials were limited.

DISCUSSION/CONCLUSIONS

Mupirocin is the best-studied agent for decolonization. Its use reduces the risk of surgical site infection following orthopedic surgery (strongest data) and cardiac surgery. Mupirocin decolonization also reduces the incidence of S. aureus clinical cultures in the intensive care unit. Povidone-iodine is less well-studied. Current data suggest that it decreases the risk of surgical site infections after orthopedic surgical procedures. In contrast, povidone-iodine is less effective than mupirocin for reducing the incidence of S aureus clinical cultures in the intensive care unit. Both mupirocin and povidone-iodine have important limitations, highlighting the need for future decolonization research.

A novel indolylbenzoquinone compound HL-J6 suppresses biofilm formation and α-toxin secretion in methicillin-resistant Staphylococcus aureus

Eradication of methicillin-resistant Staphylococcus aureus (MRSA) is challenging due to multi-drug resistance of strains and biofilm formation, the latter of which is an important barrier to the penetration of antibiotics and host defences. As such, there is an urgent need to discover and develop novel agents to fight MRSA-associated infection. In this study, HL-J6, a novel indolylbenzoquinone compound, was shown to inhibit S. aureus strains, with a minimum inhibitory concentration against MRSA252 of 2 µg/mL. Moreover, HL-J6 exhibited potent antibiofilm activity in vitro and was able to kill bacteria in biofilm. In the mouse models of wound infection, HL-J6 treatment reduced the MRSA load significantly and inhibited biofilm formation on the wounds. The potent targets of its antibiofilm activity were explored by real-time reverse transcriptase polymerase chain rection, which indicated that HL-J6 downregulated the transcription levels of sarA, atlAE and icaADBC. Moreover, Western blot results showed that HL-J6 reduced the secretion level of α-toxin, a major virulence factor. These findings indicate that HL-J6 is a promising lead compound for the development of novel drugs against MRSA biofilm infections.

Community-associated methicillin-resistant Staphylococcus aureus infection of diabetic foot ulcers in an eastern diabetic foot center in a tertiary hospital in China: a retrospective study

BACKGROUND

Diabetic foot concerns are a major public health problem. Methicillin-resistant Staphylococcus aureus (MRSA) plays a significant role in diabetic foot ulcers. Community-associated MRSA has become notorious for skin and skin soft tissue infections over the last two decades. This study investigated MRSA infection in diabetic foot patients at a tertiary hospital, focusing on the epidemiology and characteristics of community-associated MRSA.

METHODS

A total of 149 patients with diabetic foot infection whose culture results indicated Staphylococcus aureus as the source were selected. Epidemiological investigations, clinical characteristics, laboratory index records, antibiotic susceptibility analysis, and clinical outcome tracking were performed in all cases. Based on oxacillin resistance using the Vitek Compact 2 system, cases were divided into methicillin-sensitive Staphylococcus aureus and MRSA groups. Subgroup analysis of the MRSA group was performed in accordance with the Centers for Disease Control definition: community-associated MRSA and hospital-associated MRSA.

RESULTS

The MRSA group (n = 41, 27.5%) had a longer duration of ulcers and hospital stay and higher hospitalization costs than the methicillin-sensitive Staphylococcus aureus group (n = 108, 72.5%). According to the classification criteria of Infectious Diseases Society of America, the severity of infection in the community-associated MRSA group was higher than that in the hospital-associated MRSA group. The analysis of antimicrobial susceptibility of 41 MRSA isolates showed that the resistance rates to erythromycin, clindamycin, quinolone, gentamicin, tetracycline, and rifampicin were 78.0%, 68.3%, 31.7%, 17.1%, 9.8%, and 2.4%, respectively. All the MRSA strains were sensitive to linezolid, tigecycline, and vancomycin. The resistance rates to quinolones and gentamycin in the community-associated MRSA group (both 0%) were lower than those in the hospital-associated MRSA group.

CONCLUSION

Emergence of MRSA in diabetic foot ulcer was associated with a prolonged wound duration and increased consumption of medical resources. Community-associated MRSA strains predominated among MRSA isolates from diabetic foot wounds and caused more severe infections.

Bio-Stimulant for Improving Simmondsia chinensis Secondary Metabolite Production, as Well as Antimicrobial Activity and Wound Healing Abilities

Simmondsia chinensis is a dioecious, long-lived perennial shrub. Its leaves contain several antioxidant flavonoids that have numerous pharmacological effects. Various strategies have been explored to propagate jojoba with enhanced pharmacological values. This research evaluates the bio-stimulatory impacts of He-Ne laser seed irradiation on seed germination, plantlet growth, and alteration of the composition and bioactivities of phytochemicals in jojoba plants. Jojoba seeds were irradiated for 5, 10, and 15 min before in vitro germination. Germination, growth, and multiplication parameters were recorded during germination, multiple-shoot induction, and rooting stages. The wound healing and antimicrobial activities of methanolic extracts from plant lines obtained from the non-irradiated (control) and 10 min irradiated seeds were compared by excision wound model in Wistar male rats and zone of inhibition assay. Our study revealed that laser irradiation increased seed germination, with the highest percentage observed in seeds irradiated for 10 min. Plant lines from the 10 min irradiated seeds produced more explants with higher explant heights and numbers of leaves, more roots, and higher photosynthetic pigment contents than those of control and other laser testings. By comparing plant extracts from the control and 10 min treatments, we observed that extracts from the 10 min treatment exhibited higher percentages of wound contraction and shorter epithelialization periods. In addition, these extracts also resulted in higher levels of angiogenesis elements (VEGF, TGF-β1, and HIF-1α) and reduced the inflammation regulators (IL-1β, IL-6, TNF-α, and NFκB) in the experimental rats. In concordance, extracts from the 10 min treatment also explained raised antibacterial activities towards Staphylococcus aureus and Escherichia coli. Our findings show that pre-sowing seed treatment with a He-Ne laser (632.8 nm) could be a good technique for stimulating S. chinensis plant growth and increasing the impact compound levels and biological activities.

Whole-genome sequencing analysis of molecular epidemiology and silent transmissions causing meticillin-resistant Staphylococcus aureus bloodstream infections in a university hospital

BACKGROUND

The emergence of novel genomic-type clones, such as community-associated meticillin-resistant Staphylococcus aureus (MRSA) and livestock-associated MRSA, and their invasion into hospitals have become major concerns worldwide; however, little information is available regarding the prevalence of MRSA in Japan. Whole-genome sequencing (WGS) has been conducted to analyse various pathogens worldwide. Therefore, it is important to establish a genome database of clinical MRSA isolates available in Japan.

AIM

A molecular epidemiological analysis of MRSA strains isolated from bloodstream-infected patients in a Japanese university hospital was conducted using WGS and single-nucleotide polymorphism (SNP) analysis. Additionally, through a review of patients' clinical characteristics, the effectiveness of SNP analysis as a tool for detecting silent nosocomial transmission that may be missed by other methods was evaluated in diverse settings and various time points of detection.

METHODS

Polymerase-chain-reaction-based staphylococcal cassette chromosome mec (SCCmec) typing was performed using 135 isolates obtained between 2014 and 2018, and WGS was performed using 88 isolates obtained between 2015 and 2017.

FINDINGS

SCCmec type II strains, prevalent in 2014, became rare in 2018, whereas the prevalence of SCCmec type IV strains increased from 18.75% to 83.87% of the population, and became the dominant clones. Clonal complex (CC) 5 CC8 and CC1 were detected between 2015 and 2017, with CC1 being dominant. In 88 cases, SNP analyses revealed nosocomial transmissions among 20 patients which involved highly homologous strains.

CONCLUSIONS

Routine monitoring of MRSA by whole-genome analysis is effective not only for gaining knowledge regarding molecular epidemiology, but also for detecting silent nosocomial transmission.

Enterotoxins A and B produced by Staphylococcus aureus increase cell proliferation, invasion and cytarabine resistance in acute myeloid leukemia cell lines

As in the case of cancer, the risk of infection increases when the host's immune system is not working properly. It has been shown that toxins produced by the bacteria responsible for bacterial infections can alter the properties of cancer cells as well as their sensitivity to chemotherapy agents. Staphylococcus aureus (S. aureus) is one of the most prevalent pathogens in acute myeloid leukemia (AML) patients and it produces several virulence factors, including Staphylococcal enterotoxin A (SEA) and Staphylococcal enterotoxin B (SEB). Cytotoxicity, transwell migration, invasion assays, and various transcriptomic and gene set enrichment (GSE) analyses were used to determine how SEA and SEB alter cell proliferation, migration, invasion, and Cytarabine (Cyt) resistance in AML cell lines. The treatment of AML cell lines with SEA/SEB caused an increase in cell proliferation and Cyt resistance. Toxins enhanced the proclivity of cells to migrate and invade, with around 50% of cells in the presence of SEA and SEB. Transcriptomic and gene set enrichment analyses, and subsequent PCR validations showed dysregulation of immune related genes and genesets. Apparently, this allows AML cells to escape and survive the undesirable environment created by toxins, possibly via the ER stress signaling pathway. Therefore, SEA and SEB can significantly alter the characteristics of AML cancer cells and evaluation of alterations in responsible immune genes and pathways may be crucial for controlling the progression of cancer. In addition, our results suggest that there may be a strong interaction between the immune related pathways and the ER signaling pathway.

Targeting hemoglobin receptors IsdH and IsdB of Staphylococcus aureus with a single VHH antibody inhibits bacterial growth

Methicillin-resistant Staphylococcus aureus, or MRSA, is one of the major causative agents of hospital-acquired infections worldwide. Novel antimicrobial strategies efficient against antibiotic-resistant strains are necessary and not only against S. aureus. Among those, strategies that aim at blocking or dismantling proteins involved in the acquisition of essential nutrients, helping the bacteria to colonize the host, are intensively studied. A major route for S. aureus to acquire iron from the host organism is the Isd (iron surface determinant) system. In particular, the hemoglobin receptors IsdH and IsdB located on the surface of the bacterium are necessary to acquire the heme moiety containing iron, making them a plausible antibacterial target. Herein, we obtained an antibody of camelid origin that blocked heme acquisition. We determined that the antibody recognized the heme-binding pocket of both IsdH and IsdB with nanomolar order affinity through its second and third complementary-determining regions. The mechanism explaining the inhibition of acquisition of heme in vitro could be described as a competitive process in which the complementary-determining region 3 from the antibody blocked the acquisition of heme by the bacterial receptor. Moreover, this antibody markedly reduced the growth of three different pathogenic strains of MRSA. Collectively, our results highlight a mechanism for inhibiting nutrient uptake as an antibacterial strategy against MRSA.

1,8-Cineol (Eucalyptol) Disrupts Membrane Integrity and Induces Oxidative Stress in Methicillin-Resistant Staphylococcus aureus

Due to the increased emergence of drug-resistant bacteria, the declining efficiency of traditional antimicrobials has generated severe concerns in recent years. Subsequently, more interest in other antimicrobial agents from natural resources draws more attention as an alternative to conventional medications. This study investigated the bactericidal mechanism of monoterpene 1,8-cineol (eucalyptol), a major compound of various essential oils, against methicillin-resistant Staphylococcus aureus (MRSA). The antibacterial activity of 1,8-cineol was assessed by an MTT assay against clinical and reference MRSA strains. A cell membrane integrity test, followed by zeta potential (ZP) measurements, was performed to evaluate the disruption of the bacterial membrane integrity. Additionally, the cytotoxic effect of this molecule on MRSA bacteria was investigated by monitoring reactive oxygen species (ROS) generation, lipid peroxidation (MDA), and antioxidant enzyme activities (CAT and SOD). Regarding the anti-staphylococcal effect, the obtained results revealed the antibacterial efficacy of 1,8-cineol wherein the minimum inhibitory concentrations were equal to 7.23 mg/mL. Furthermore, it enhanced membrane permeability, with a 5.36-fold increase in nucleic acid and protein leakage as compared with untreated strains, along with the alteration of surface charge (ZP) in MRSA cells. The tested compound caused an increase in ROS generation reaching 17,462 FU and MDA production, reaching 9.56 μM/mg protein, in treated bacterial cells, along with a decrease in oxidative stress enzymes activities. Our findings suggest that 1,8-cineol has the ability to damage the membrane integrity and induce ROS-mediated oxidative stress in MRSA cells, leading to its antagonistic effect against this pathogen and consequently aiding in the reversal of antibiotic resistance.

Tannin extracted from Penthorum chinense Pursh, a potential drug with antimicrobial and antibiofilm effects against methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is an opportunistic pathogen. Due to the widespread use and abuse of antibiotics, various drug-resistant strains of S. aureus have emerged, with methicillin-resistant Staphylococcus aureus (MRSA) being the most prevalent. Bacterial biofilm is a significant contributor to bacterial infection and drug resistance. Consequently, bacterial biofilm formation has emerged as a therapeutic strategy. In this study, the chemical constituents, antimicrobial and antibiofilm properties of tannins isolated from Penthorum chinense Pursh (TPCP) were investigated. In vitro, TPCP exhibited antimicrobial properties. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA were 156.25 and 312.5 μg/mL, and 312.5 and 625 μg/mL, respectively. According to the growth curves, TPCP significantly inhibited the growth of MSSA and MRSA. The results of the crystal violet biofilm assay in conjunction with confocal laser scanning and scanning electron microscopy demonstrated that TPCP destroyed preformed MSSA and MRSA biofilms. TPCP significantly decreased the secretion of exopolysaccharides and extracellular DNA. Subsequently, the mechanism was investigated using RT-PCR. Examining the expression of icaA, cidA, sigB, agrA, and sarA genes in MRSA, we discovered that TPCP inhibited biofilm formation by affecting the quorum-sensing system in bacteria. Our study demonstrates that TPCP exerts antibacterial effects by disrupting the formation of bacterial biofilms, suggesting that TPCP has clinical potential as a novel antibacterial agent for the prevention and treatment of MSSA and MRSA infections.

Recent updates in the development of molecular assays for the rapid identification and susceptibility testing of MRSA

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of healthcare- and community-associated infections. Nasal carriage of MRSA is a risk factor for subsequent MRSA infections. Increased morbidity and mortality are associated with MRSA infections and screening and diagnostic tests for MRSA play an important role in clinical management.

AREAS COVERED

A literature search was conducted in PubMed and supplemented by citation searching. In this article, we provide a comprehensive review of molecular-based methods for MRSA screening and diagnostic tests including individual nucleic acid detection assays, syndromic panels, and sequencing technologies with a focus on their analytical performance.

EXPERT OPINION

Molecular based-assays for the detection of MRSA have improved in terms of accuracy and availability. Rapid turnaround enables earlier contact isolation and decolonization for MRSA. The availability of syndromic panel tests that include MRSA as a target has expanded from positive blood cultures to pneumonia and osteoarticular infections. Sequencing technologies allow detailed characterizations of novel methicillin-resistance mechanisms that can be incorporated into future assays. Next generation sequencing is capable of diagnosing MRSA infections that cannot be identified by conventional methods and metagenomic next-generation sequencing (mNGS) assays will likely move closer to implementation as front-line diagnostics in the near future.