Antibacterial and antioxidant properties of sumac extract on methicillin-resistant Staphylococcus aureus.

The research aimed to evaluate the antioxidative and antibacterial characteristics of aqueous sumac extract on methicillin-resistant Staphylococcus aureus through in-vitro and in-vivo study. Sumac extract has been obtained through the soaking method, and its antioxidant properties were gauged using the DPPH free radical scavenging method. The minimum inhibitory concentration (MIC) of sumac extract was determined on S. aureus obtained from hospitalized patients, as well as an assessment of biofilm-formation and the release of bacterial intracellular compounds. in vivo experimentation involved injecting bacteria (108 cfu/ml) into mice, which subsequently manifested indicators of symptoms of infection, and the number of bacteria within their bloodstream was quantified. The Sumac extract demonstrated strong antioxidant properties at concentrations of 1000 mg/ml. Furthermore, the agar tests for the gram staining, mannitol, coagulase, and DNase revealed that 190 cultured bacteria samples were identified as Staphylococcus aureus. These bacteria were resistant to clindamycin, ciprofloxacin, and methicillin antibiotics, but sensitive to erythromycin and penicillin antibiotics. Additionally, the bacteria displayed significant methicillin resistance and formed a strong biofilm (65.78%). The sumac extract showed a MIC range of 125-1000 µg/ml against Staphylococcus aureus. Treatment with concentrations above the MIC was found to prevent the formation of biofilm and increase the release of bacterial intracellular compounds. Sumac extract led to a decrease in bacterial count in the blood of mice and reduced signs of infection. Sumac extract demonstrated powerful antioxidant and antibacterial effects against resistant microorganisms, suggesting its potential as a promising compound for the treatment of resistant infections in future research.

A new antibacterial with anti-inflammatory properties promotes wound healing through inhibiting cGAS/STING/NF-κB/IRF3 pathway.

Benzothiazole-urea hybrid 8l was found to be a potent anti-bacterial agent against methicillin-resistant Staphylococcus aureus (MRSA2858) (MIC = 0.78 µM, Eur J Med Chem. 2022,236:114333). Herein, 8l was further evaluated to remedy the MRSA-infected scald with bacterial infection and severe inflammation. In scalded skin model with MRSA infection, 8l not only effectively reduced bacterial load, but also decreased pro-inflammatory cytokines secretion and promoted collagen deposition to effectively reverse the progression of wound infection and inflammation by blocking cGAS/STING/NF-κB/IRF3 signaling pathway. In vitro model of RAW264.7 cells verified that 8l can inhibit MRSA-induced inflammation via regulating this pathway. All in all, dual anti-bacterial and anti-inflammatory agent 8l could heal MRSA-infected refractory scald by regulating cGAS/STING/NF-κB/IRF3 pathway.

Eliminating Intracellular MRSA via Mannosylated Lipid-Coated Calcium Phosphate Nanoparticles.

Methicillin-resistant Staphylococcus aureus (MRSA) within cells proves exceptionally challenging to eradicate using conventional antimicrobials, resulting in recurring infections and heightened resistance. Herein, we reported an innovative mannosylated lipid-coated photodynamic/photothermal calcium phosphate nanoparticle (MAN-LCaP@ICG) for eradicating intracellular MRSA. The MAN-LCaP functioned as the vehicle for drug delivery, exhibiting preferential uptake by macrophages and facilitating the transport of ICG to intracellular pathogens. The MAN units integrated into MAN-LCaP@ICG could promote binding with MAN residuals on macrophage cells, as evidenced by cellular uptake assays using fluorescence microscopy and flow cytometry. Following its targeted accumulation, MAN-LCaP@ICG could enter into the cytoplasm and efficiently eradicate intracellular MRSA by a combination of the lysosome escape capability of CaP and the photodynamic and photothermal therapeutic effects of ICG. Furthermore, MAN-LCaP@ICG could kill MRSA more effectively than LCaP@ICG without MAN units or free ICG in a mouse peritoneal infection model. Therefore, MAN-LCaP@ICG provided a promising direction for human clinical application in combating intracellular infections.

Prevalence of Bacteremia and Antimicrobial Resistance Pattern Among Patients in South Lebanon.

BACKGROUND: Bacteremia are a leading cause of morbidity and mortality worldwide. Rising prevalence and antimicrobial resistance (AMR) are critical public health issues. This study aims to determine the prevalence of bacteremia and the antimicrobial resistance pattern among patients in South Lebanon. METHODS: A cross-sectional study analyzed 76 positive blood cultures from Hammoud and Labib Hospitals in South Lebanon between September 2023 and March 2024.The phenotype and antimicrobial susceptibility of gram-positive and gram-negative was determined by using disk diffusion. Genotypically, PCR was used to detect the carbapenemase-resistant Enterobacterales (CRE), extended-spectrum ß-lactamases (ESBL) and Methicillin Resistant Staphylococcus aureus (MRSA) genes. RESULTS: Out of 76 isolates, 38(50%) were gram-positive and 38(50%) were gram-negative. Escherichia coli was the most common among gram-negative (18. 42%), with 10.52% ESBL and 3.94% CRE. Staphylococcus coagulase negative was the most common among gram-positive (40.78%), followed by S. aureus (6.57%), with 3.94% MRSA.The prevalent ESBL gene was CTX-M (100%), and for the CRE, NDM (66.66%). Regarding S. aureus, (66.66%) were mecA. DISCUSSION: The diverse bacteremia isolates and resistance genes in South Lebanon reflect global variability in incidence and resistance profiles. CONCLUSION: High rates of bacteremia and AMR in South Lebanon underscore the need for effective antibiotic stewardship programs.

Spermidine Associated with Gut Microbiota Protects Against MRSA Bloodstream Infection by Promoting Macrophage M2 Polarization.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen that causes various diseases. Extensive researches highlight the significant role of gut microbiota and its metabolites, particularly spermidine, in infectious diseases. However, the immunomodulatory mechanisms of spermidine in MRSA-induced bloodstream infection remain unclear. Here, we confirmed the protective effects of spermidine in bloodstream infection in mice. Spermidine reduced the bacterial load and expression of inflammatory factors by shifting the macrophage phenotype to an anti-inflammatory phenotype, ultimately prolonging the survival of the infected mice. The protective effect against MRSA infection may rely on the elevated expression of protein tyrosine phosphatase nonreceptor 2 (PTPN2). Collectively, these findings confirm the immunoprotective effects of spermidine via binding to PTPN2 in MRSA bloodstream infection, providing new ideas for the treatment of related infectious diseases.

Role of Xpert PCR kit in assessing MRSA colonization in medical and surgical units of a tertiary care teaching hospital.

BACKGROUND AND RATIONALE: Methicillin resistant Staphylococcus aureus (MRSA) colonization increases the risk of MRSA infection. Detecting MRSA colonization can influence postoperative outcomes and prolong hospital stay. The conventional standard culture method for detecting MRSA colonization has limitations in terms of sensitivity and turnaround time. Hence, we sought out use of Xpert PCR kit for prompt evaluation of MRSA colonization to support MRSA prevention in a tertiary care hospital in Karachi, Pakistan. MATERIALS AND METHODS: During 1st April-31st December 2022, 290 nasal and skin swab samples were collected from 257 patients and processed using routine culture (as gold standard method) and PCR-based MRSA detection assay (MRSA Xpert). RESULTS: A total of two hundred and ninety (290) swab samples from 257 patients were obtained, 33 of which were paired. The overall prevalence of MRSA colonization was 12% by both methods, with 90% of cases classified as community-associated (CA-MRSA) whereas 10% as hospital-acquired (HA-MRSA). The colonized group showed a higher subsequent MRSA infection rate (11% vs. 3.5%) compared to the noncolonized group. Culture identified 11% of screening samples as MRSA positive, Xpert MRSA assay showed 100% sensitivity and 95% specificity. The cost of a single MRSA Xpert assay was $50 while MRSA culture cost around $7.50. CONCLUSION: Our study findings suggest that the presence of MRSA colonization in our cohort of patients is consistent with the existing trends in hospital epidemiology. Both conventional culture and Xpert MRSA methods showed comparable efficacy for detection of MRSA colonization. Larger-scale studies are recommended to validate these findings conclusively.

Bactericidal and anti-quorum sensing activity of repurposing drug visomitin against staphylococcus aureus.

With the growing antibiotic resistance in Staphylococcus aureus, it is imperative to develop innovative therapeutic strategies against new targets to reduce selective survival pressures and incidence of resistance. In S. aureus, interbacterial communication relies on a quorum sensing system that regulates gene expression and physiological activities. Here, we identified that Visomitin, an antioxidant small molecule, exhibited bactericidal efficacy against methicillin-resistant S. aureus and its high tolerance phenotypes like intracellular bacteria and persister cells without inducing resistance. Critically, sub-minimal inhibitory concentrations (sub-MICs) of Visomitin could serve as a potent quorum-quencher reducing virulence production (such as haemolysin and staphyloxanthin), along with inhibiting biofilm formation, self-aggregation, and colony spreading of S. aureus. These effects were probably mediated by interfering with the S. aureus accessory gene regulator quorum sensing system. In summary, our findings suggest that Visomitin shows dual antimicrobial effects, including bactericidal effects at the concentrations above MIC and quorum sensing inhibition effects at sub-MICs, which holds promise for treating MRSA-related refractory infections.

Microbiota of Chronic Suppurative Otitis Media and its Radiological Correlation in Severity of Disease.

Objective: The objective of the study was to find out the microbiota of cases of chronic suppurative otitis media and its radiological correlation in disease severity. Methodology: 50 patients with CSOM were prospectively studied. Swabs were taken and cultured for bacteria. HRCT temporal bone was done and microbiota relation with severity was studied. Result: We found the predominant organism to be staphylococcus aureus (44%) followed by psedumonas (22%). On radiological correlation maximum erosive property was seen with pseudomonas followed by methicillin sensitive staphylococcus aureus and Coagulase negative staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus prevalence in food-producing animals and food products in Saudi Arabia: A review.

In Saudi Arabia, the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in food and livestock represents a major public health hazard. The emergence of livestock-associated MRSA has heightened the risk of human infection with comparable virulence traits. The lack of information about MRSA transmission in our region hinders accurate risk assessment, despite its detection in food animals and retail foods. Adopting a One Health approach is essential for effectively combating MRSA in Saudi Arabia. This method unites actions in the human, animal, and environmental spheres. To combat MRSA contamination, surveillance measures need strengthening; interdisciplinary collaboration among healthcare professionals, veterinarians, and environmental scientists is crucial, and targeted interventions must be implemented in local food chains and animal populations. Through a holistic strategy, public health and sustainable food production in the region are protected. This review aims to improve public health interventions by increasing understanding of MRSA prevalence and related risks in local food chains and animal populations.

ST105 Lineage of MRSA: An Emerging Implication for Bloodstream Infection in the American and European Continents.

Sequence-type 5 (ST5) of methicillin-resistant Staphylococcus aureus (MRSA), harboring the staphylococcal chromosomal cassette mec type IV (SCCmecIV), was first detected in Portugal. It emerged as a significant cause of healthcare-associated (HA) infection in pediatric units and was hence named the pediatric clone. Another ST5 lineage, which carries SCCmecII, also prevailed in the USA and Japan for multiple years. More recently, another MRSA lineage, ST105-SCCmecII, part of the evolution of clonal complex 5 (CC5) MRSA, has emerged as the cause of hospital-acquired bloodstream infection outbreaks in countries including Portugal, the USA, and Brazil. This article reviews studies on the epidemiology and evolution of these newly emerging pathogens. To this end, a search of PUBMED from inception to 2024 was performed to find articles reporting the occurrence of ST105 MRSA in epidemiologic studies. A second search was performed to find studies on MRSA, CC5, ST5, and SCCmecII. A search of PUBMED from 1999 to 2024 was also performed to identify studies on the genomics and evolution of ST5, CC5, and ST105 MRSA. Further studies were identified by analyzing the references of the previously selected articles from PUBMED. Most articles on ST105 MRSA were included in this review. Only articles written in English were included. Furthermore, only studies that used a reliable genotyping method (e.g., whole genome sequencing, or MLST) to classify the CC5 lineages were selected. The quality and selection of articles were based on the consensus assessment of the three authors in independent evaluations. In conclusion, ST105-SCCmecII is an emerging MRSA in several countries, being the second/third most important CC5 lineage, with a relatively high frequency in bloodstream infections. Of concern is the increased mortality from BSI in patients older than 15 years and the higher prevalence of ST105-SCCmecII in the blood of patients older than 60 years reported in some studies.

In Vivo Effect of Halicin on Methicillin-Resistant Staphylococcus aureus-Infected Caenorhabditis elegans and Its Clinical Potential.

Recently, the high proportion of methicillin-resistant Staphylococcus aureus infections worldwide has highlighted the urgent need for novel antibiotics to combat this crisis. The recent progress in computational techniques for use in health and medicine, especially artificial intelligence (AI), has created new and potential approaches to combat antibiotic-resistant bacteria, such as repurposing existing drugs, optimizing current agents, and designing novel compounds. Halicin was previously used as a diabetic medication, acting as a c-Jun N-terminal protein kinase (JNK) inhibitor, and has recently demonstrated unexpected antibacterial activity. Although previous efforts have highlighted halicin's potential as a promising antibiotic, evidence regarding its effectiveness against clinical strains remains limited, with insufficient proof of its clinical applicability. In this study, we sought to investigate the antibacterial activity of halicin against MRSA clinical strains to validate its clinical applicability, and a C. elegans model infected by MRSA was employed to evaluate the in vivo effect of halicin against MRSA. Our findings revealed the antibacterial activity of halicin against methicillin-resistant S. aureus clinical strains with MICs ranging from 2 to 4 µg/mL. Our study is also the first work to evaluate the in vivo effect of halicin against S. aureus using a C. elegans model, supporting its further development as an antibiotic.

Oral Staphylococcus Species and MRSA Strains in Patients with Orofacial Clefts Undergoing Surgical Rehabilitation Diagnosed by MALDI-TOF MS.

This study investigated the occurrence and dynamics of oral Staphylococcus species in patients with orofacial clefts undergoing surgical rehabilitation treatment. Patients (n = 59) were statistically stratified and analyzed (age, gender, types of orofacial clefts, surgical history, and types of previous surgical rehabilitation). Salivary samples were obtained between hospitalization and the return to the specialized medical center. Microbiological diagnosis was performed by classical methods, and MALDI-TOF MS. MRSA strains (SCCmec type II, III, and IV) were characterized by the Decision Tree method. A total of 33 (55.9%) patients showed oral staphylococcal colonization in one, two, or three sampling steps. A high prevalence has been reported for S. aureus (including HA-, MRSA and CA-MRSA), followed by S. saprophyticus, S. epidermidis, S. sciuri, S. haemolyticus, S. lentus, S. arlettae, and S. warneri. The dynamics of oral colonization throughout surgical treatment and medical follow-up may be influenced by (i) imbalances in staphylococcal maintenance, (ii) efficiency of surgical asepsis or break of the aseptic chain, (iii) staphylococcal neocolonization in newly rehabilitated anatomical oral sites, and (iv) total or partial maintenance of staphylococcal species. The highly frequent clinical periodicity in specialized medical and dental centers may contribute to the acquisition of MRSA in these patients.

Prevalence and anti-microbial resistance of Staphylococcus spp. isolated from the environment and veterinary personnel in a Spanish veterinary teaching hospital.

Methicillin-resistant Staphylococcus (MRS) bacteria, including methicillin-resistant S. aureus and methicillin-resistant S. pseudintermedius (MRSP), pose a significant threat in veterinary medicine, given their potential for zoonotic transmission and their implications for companion animals and humans' health. This study aimed to assess the prevalence of MRS and anti-microbial resistance patterns at a university clinical hospital in Madrid, Spain. Samples were collected from both the environment and hospital staff at Veterinary Clinical Hospital of Alfonso X el Sabio University. Anti-microbial susceptibility assays, molecular detection of mecA gene and genetic relationships among the identified bacterial strains were performed. The study revealed an MRS prevalence of 1.50% in environmental samples, with MRSP accounting for 0.75% of the cases. Genetically related MRSP strains were found in different hospital areas. Among hospital staff, there was a MRS prevalence of 14.03%, including S. pseudintermedius and S. epidermidis strains. Antibiogram tests revealed multi-drug resistance among MRSP strains. Additionally, methicillin-resistant coagulase-negative staphylococci were isolated, suggesting potential cross-species transmission. This study underscores the presence of MRS in a veterinary clinical hospital, highlighting the significance of infection control through the implementation of protective measures, stringent hygiene practices among personnel and in the environment and responsible use of antibiotics. Further research is necessary to assess MRS incidence in animal patients and explore geographical variations, enhancing our understanding of MRS in veterinary medicine and addressing its challenges.

Phenotypic and genotypic characterization of methicillin resistant Staphylococcus aureus associated with pyogenic infections.

Background and Objectives: Staphylococcal infections are one of the major infectious diseases affecting globally in spite of advances in development of antimicrobial agents. Knowledge and awareness about the local pattern and prevalence of MRSA infections plays a key role in treatment. The aim of this study was to identify MRSA strains by phenotypic and genotypic methods and to analyze the antibiotic susceptibility pattern of MRSA strains from patients attending a tertiary care hospital. Materials and Methods: This study was conducted over a period of 1 year, where 296 isolates of Staphylococcus aureus were isolated from various clinical specimens. The isolated strains were examined for antibiotic susceptibility by the modified Kirby Bauer disc diffusion method. Methicillin resistance was detected by cefoxitin disk diffusion test. Results: A total of 104 isolates were found to be MRSA and 192 were found to be MSSA. Among the 104 MRSA isolates, 10 strains that were multidrug resistant were subjected to 16S rRNA gene sequencing analysis. All the 10 strains had a 99% match with S. aureus strains that were responsible for causing some serious biofilm mediated clinical manifestations like cystic fibrosis and device mediated infections. The biofilms were quantified using crystal violet staining and their ability to produce biofilms was analyzed using scanning electron microscopy and matched with the Genbank. Conclusion: Hence these phylogenetic analysis aid in treating the patients and combating resistance to antibiotics.

Strategy against super-resistant bacteria: Curdlan-induced trained immunity combined with multi-epitope subunit vaccine.

Methicillin-resistant Staphylococcus aureus (MRSA) is rapidly spreading worldwide, emerging as a leading cause of bacterial infections in healthcare and community settings. This poses serious risks to human health. The shortage of novel antibiotics and the absence of effective vaccines make MRSA particularly challenging to treat. Existing vaccine development strategies often fail to provide early protection against infections, highlighting the urgent need for solutions. Herein, we propose a novel strategy combining trained immunity with a multi-epitope subunit vaccine to combat MRSA infections. We comprehensively evaluated the trained immune phenotypes induced by ß-glucan from barley and curdlan. Macrophages trained with curdlan exhibited a more balanced inflammatory response compared to ß-glucan from barley, expressing higher levels of IL-1ß, IFN-ß, TGF-ß, and CCL2 upon secondary stimulation. Furthermore, curdlan-induced trained immunity rapidly provided excellent protection against S. aureus infection in mice. RNA-sequencing analysis revealed that curdlan modulates the Wnt signaling pathway in macrophages, resolves inflammation, and promotes tissue repair. When combined with one or two doses of S. aureus multivalent epitope antigen against MRSA infection, curdlan-induced trained immunity enhanced early protection and promoted recovery. Our study demonstrates the feasibility of combining trained immunity with vaccine protection against MRSA, providing a strategy against multi-drug resistant bacteria.

Prevalence and Antibiotic Resistance Patterns of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Hospital Setting: A Retrospective Study from 2018 to 2022.

Methicillin-resistant Staphylococcus aureus (MRSA) is a highly infectious pathogen that poses a serious threat to human life and health. This study aimed to provide a scientific basis for the rational clinical use of antimicrobial drugs for treating MRSA infections and inform the development of preventive and control measures by analyzing the clinical distribution and resistance characteristics of MRSA in a hospital in Hebei China. To accomplish this, bacterial identification and drug sensitivity experiments were performed with 1858 Staphylococcus aureus (S. aureus) strains collected from a hospital from January 2018 to December 2022 using a phoenixTM-100 bacterial identification drug sensitivity analyzer. The experimental data were analyzed using WHONET 5.6 software, and the MRSA strains detected were analyzed for their clinical distribution and drug resistance. Of the 1858 S. aureus strains isolated, 429 were MRSA. Sputum samples had the highest MRSA detection rates (52.45%). Critical care medicine had the highest rate of MRSA (12.59%), followed by dermatology (9.79%). MRSA resistance to tetracycline increased by 13.9% over 5 years; resistance to quinupristin/dalfopristin also increased but remained low (1.9%). Resistance decreased to gentamicin, rifampicin, ciprofloxacin, and cotrimoxazole, though most significantly to erythromycin and clindamycin, exceeding 77% and 83%, respectively. No strains were resistant to vancomycin, teicoplanin, or linezolid, and drug resistance was most prevalent in patients ≥ 60 years old. This study will aid in improving the diagnosis and treatment of MRSA infections.

Prevalence and risk factors associated with nasal carriage of methicillin-resistant staphylococci in horses and their caregivers.

Antimicrobial resistance is a global threat, and pet-associated strains may pose a risk to human health. Equine veterinarians are at high risk of carrying methicillin-resistant staphylococci (MRS), but specific risk factors remain elusive, and few data are available for other personnel involved in the horse industry. The prevalence, characteristics, and risk factors for nasal carriage of MRS in horses and their caregivers were studied in northwestern Italy. Nasal swabs from 110 asymptomatic horses housed at 21 barns and 34 human caregivers were collected. Data on barns, horses, and personnel were acquired through questionnaires. The samples were incubated in selective media, and the bacterial isolates were identified by mass spectrometry. Risk factors were investigated by Poisson regression. MRS were isolated from 33 horses (30%), 11 humans (32.4%) and 3 environmental samples (14.2%). Most isolates were multidrug resistant (MDRS). The prevalence of MRS and MDRS was greater in racehorses and their personnel than in pleasurable and jumping/dressing horses. MRS carriage in caregivers was associated with an increased prevalence of MRS carriage in horses. The frequency of antimicrobial treatments administered in the barn during the last 12 months was a risk factor for MRS carriage in horses [prevalence ratio (PR) 3.97, 95% CI 1.11, 14.13] and caregivers (PR 2.00, 95% CI 1.05, 3.82), whereas a good ventilation index of the horse tabling environment was a protective factor (PR 0.43, 95% CI 0.20, 0.92). Our data reveal relevant interactions occurring between bacterial communities of horses and humans that share the same environment, suggesting that One Health surveillance programs should be implemented.

Discovery of membrane-targeting amphiphilic honokiol derivatives containing an oxazolethione moiety to combat methicillin-resistant Staphylococcus aureus (MRSA) infections.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major pathogen causing infections in hospitals and the community, and there is an urgent need for the development of novel antibacterials to combat MRSA infections. Herein, a series of amphiphilic honokiol derivatives containing an oxazolethione moiety were prepared and evaluated for their in vitro antibacterial and hemolytic activities. The screened optimal derivative, I3, exhibited potent in vitro antibacterial activity against S. aureus and clinical MRSA isolates with MIC values of 2-4 µg/mL, which was superior to vancomycin in terms of its rapid bactericidal properties and was less susceptible to the development of resistance. The SARs analysis indicated that amphiphilic honokiol derivatives with fluorine substituents had better antibacterial activity than those with chlorine and bromine substituents. In vitro and in vivo toxicity studies revealed that I3 has relatively low toxicity. In a MRSA-infected mouse skin abscess model, I3 (5 mg/kg) effectively killed MRSA at the infected site and attenuated the inflammation effects, comparable to vancomycin. In a MRSA-infected mouse sepsis model, I3 (12 mg/kg) was found to significantly reduce the bacterial load in infected mice and increase survival of infected mice. Mechanistic studies indicated that I3 has membrane targeting properties and can interact with phosphatidylglycerol (PG) and cardiolipin (CL) of MRSA cell membranes, thereby disrupting MRSA cell membranes, further inducing the increase of reactive oxygen species (ROS), protein and DNA leakage to achieve rapid bactericidal effects. Finally, we hope that I3 is a potential candidate molecule for the development of antibiotics to conquer superbacteria-related infections.

Pharmacokinetics of vancomycin in sputum of intubated patients: Optimized intravenous delivery vs. inhaled therapy.

AIMS: Intubated patients with methicillin-resistant Staphylococcus aureus pneumonia, fail optimized treatment with intravenous (IV) vancomycin (serum trough 15-20 µg/mL) in 38-79% of cases. Airway blood flow is diminished compared to alveoli and we hypothesized that vancomycin concentrations achieved in airway secretions are suboptimal and nonbactericidal. Targeted therapy by inhalation may overcome this deficit. METHODS: Airway pharmacokinetics of optimized IV and inhaled vancomycin in infected clinically stable prolonged mechanically ventilated patients were measured. First, IV vancomycin was given until optimized concentrations were achieved (15-20 µg/mL), and, at the same time point, sputum vancomycin concentrations were measured. Then, sputum concentrations were re-assessed after 4 treatments of inhaled vancomycin (120 mg/2 mL) via a previously characterized nebulizing system that deposited 18 ± 2 mg in the lungs. Vancomycin post-distribution phase serum peak and trough concentrations were also obtained. Serum albumin was measured to assess binding to vancomycin. RESULTS: Mean serum trough concentration was 18.4 ± 6.5 µg/mL. Sputum concentrations were affected by serum albumin. Only patients with severe hypoalbuminaemia had penetration of drug leading to therapeutic (15.7-17 µg/mL) sputum concentrations. Following inhaled vancomycin, sputum concentrations increased significantly to 199 ± 37.0 µg/mL (P = .002) exceeding minimum inhibitory concentration by 2 orders of magnitude. CONCLUSION: Despite optimized serum concentrations, patients with albumin near normal had suboptimal concentrations of vancomycin in their sputum. Inhaled therapy may be clinically important for successful treatment of ventilator-associated methicillin-resistant Staphylococcus aureus infection. Further studies of inhaled therapy are needed to define their role as adjunctive therapy in ventilator-associated pneumonia and as single therapy in tracheobronchitis.

Rapid and sensitive detection of methicillin-resistant Staphylococcus aureus through the RPA-PfAgo system.

Introduction: Both the incidence and mortality rates associated with methicillin-resistant Staphylococcus aureus (MRSA) have progressively increased worldwide. A nucleic acid testing system was developed in response, enabling swift and precise detection of Staphylococcus aureus (S. aureus) and its MRSA infection status. This facilitates improved prevention and control of MRSA infections. Methods: In this work, we introduce a novel assay platform developed by integrating Pyrococcus furiosus Argonaute (PfAgo) with recombinase polymerase amplification (RPA), which was designed for the simultaneous detection of the nuc and mecA genes in MRSA. Results: This innovative approach enables visual MRSA detection within 55 mins, boasting a detection limit of 102 copies/µL. Characterized by its high specificity, the platform accurately identifies MRSA infections without cross-reactivity to other clinical pathogens, highlighting its unique capability for S. aureus infection diagnostics amidst bacterial diversity. Validation of this method was performed on 40 clinical isolates, demonstrating a 95.0% accuracy rate in comparison to the established Vitek2-COMPACT system. Discussion: The RPA-PfAgo platform has emerged as a superior diagnostic tool, offering enhanced sensitivity, specificity, and identification efficacy for MRSA detection. Our findings underscore the potential of this platform to significantly improve the diagnosis and management of MRSA infection.