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The occurrence of Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) in a sub-catchment of the Yodo River Basin, a representative water system of a drinking water source in Japan, was investigated. The chromogenic enzyme-substrate medium method was used for the detection of S. aureus and MRSA by the presence or absence of antimicrobials in the medium for viable bacteria in a culture-based setting. The contributions of S. aureus and MRSA from wastewater to the rivers were estimated based on mass flux-based analysis, and quantitative microbial risk assessment (QMRA) was further conducted for S. aureus and MRSA in river environments. The mean abundance of S. aureus and MRSA was 31 and 29 CFU/mL in hospital effluent, 124 and 117 CFU/mL in sewage treatment plant (STP) influent, 16 and 13 CFU/mL in STP effluent, and 8 and 9 CFU/mL in river water, respectively. Contribution of the pollution load derived from the target STP effluent to river water ranged from 2% to 25%. The QMRA showed that to achieve the established health benchmarks, the drinking water treatment process would need to yield 1.7 log10 and 2.9 log10 inactivation in terms of infection risk and disability-adjusted life year (DALY) indexes, respectively. These findings highlight the link between medical environment and the importance of environmental risk management for antimicrobial-resistant bacteria in aquatic environments.

Confronted with the severe situation that the pace of resistance acquisition is faster than the clinical introduction of new antibiotics, health organizations are calling for effective approaches to combat methicillin‐resistant Staphylococcus aureus (MRSA) infections. Here, an approach to treat MRSA through photolysis of staphyloxanthin, an antioxidant residing in the microdomain of S. aureus membrane, is reported. This photochemistry process is uncovered through transient absorption imaging and quantitated by absorption spectroscopy, Raman spectroscopy, and mass spectrometry. Photolysis of staphyloxanthin transiently elevates the membrane permeability and renders MRSA highly susceptible to hydrogen peroxide attack. Consequently, staphyloxanthin photolysis by low‐level 460 nm light eradicates MRSA synergistically with hydrogen peroxide and other reactive oxygen species. The effectiveness of this synergistic therapy is well validated in MRSA planktonic culture, MRSA‐infected macrophage cells, stationary‐phase MRSA, persisters, S. aureus biofilms, and two mice wound infection models. Collectively, the work demonstrates that staphyloxanthin photolysis is a new therapeutic platform to treat MRSA infections. Methicillin‐resistant Staphylococcus aureus (MRSA) has caused a wide range of infections from mild skin infections to bacteremia due to the resistance. It is shown that staphyloxanthin, an important virulence factor residing inside the membrane microdomain, can be efficiently photolyzed by blue light, thus rendering MRSA highly sensitive to reactive oxygen species attack.

Background The responsible for staph infection is methicillin‐resistant Staphylococcus aureus (MRSA) which has a long and difficult treatment process due to resistance to this type of antibiotic. This study is designed to investigate the distribution and frequency of antibiotic‐resistant genes and MRSA enterotoxins isolated from the meat and edible viscera of broiler chickens, which are responsible for pathogenicity in humans. Materials and Methods A total of 523 meat and edible viscera of broiler chicken collected from farms in Shahrekord, Iran. The antibiogram test of 142 MRSA isolates was performed by Kirby‐Bauer diffusion disc. Sensitivity or resistance of MRSA was tested on 13 different antibiotics. DNA extracted from MRSA was screened by PCR technique for the presence of antibiotic‐resistant and enterotoxin genes. Results Staphylococcus aureus (S. aureus) isolated with frequency of 51.05% (267 of 523). The presence of mecA gene in S. aureus was examined to detect the MRSA. The most antibiotic‐resistance responsible genes and the pathogenic enterotoxin genes were identified. MRSA was identified by positive amplification of mecA in 53.18% (142 of 267) of S. aureus isolates. S. aureus antimicrobial resistance was most frequently noted against tetracycline (94.37%), ampicillin (88.73%) and penicillin (71.83%). Out of 51 examined isolates, 47 isolates exhibited the sea (92.15%), and 7 isolates exhibited the sej (13.72%). Conclusion The results indicated high prevalence of MRSA in broilers, which is very worrying issue. In addition, in the present study, it was observed that due to the increase in the use of antibiotics in poultry farming, bacteria resistant to methicillin and other antibiotics have a high prevalence. Now, with the knowledge that the consumption of broiler chicken is very high all over the world and with the increasing trend of antibiotic consumption, this issue has become a concern at the global health level. The presence of antibiotic‐resistance and enterotoxigenic genes in MRSA bacteria is a critical threat to human nutrition, making consuming contaminated meat and edible viscera of broiler chickens unsafe. The results indicated high prevalence of MRSA in broilers, which is very worrying issue. It was observed that due to the increase in the use of antibiotics in poultry farming, bacteria resistant to methicillin and other antibiotics have a high prevalence. Now, with the knowledge that the consumption of broiler chicken is very high all over the world and with the increasing trend of antibiotic consumption, this issue has become a concern at the global health level.

Methicillin‐resistant Staphylococcus aureus (MRSA) is a prevalent and highly virulent bacterium encountered in clinical settings. Due to its uneven drug resistance profile and the multitude of factors influencing detection rates, precise and sensitive identification of MRSA is essential. Herein, we developed a detection system (called “APC‐Cas‐PLNPs”) that can ultrasensitive detection for MRSA, using a nucleic acid‐based allosteric probe, CRISPR‐Cas12a, and dual‐colored persistent luminescent nanoparticles tandem detection. Simply, an allosteric probe was used to specifically recognize MRSA and cyclic signal amplification and then initiated catalytic CRISPR‐Cas12a collateral cleavage. Meanwhile, red‐emitting ZnGa2O4:Cr (ZGC) bonded with BHQ3‐modified single‐stranded DNA to create a detection probe known as ZGC@BHQ3, and green‐emitting Zn2GeO4:Mn (ZGM) was served as the reference probe and electrostatically bound to both probes, forming the ratiometric luminescence sensor ZGC@BHQ3‐ZGM for CRISPR‐Cas12a detection. With this strategy, the nonnucleic acid targets were dexterously converted into fluorescent signals. This tandem detection system eliminates interference from background fluorescence and external factors and provides a novel signal amplification and conversion strategy, which enables accurate and sensitive quantification of MRSA (1–105 CFU/mL) without requiring isolation and DNA extraction. Moreover, APC‐Cas‐PLNPs are capable of detecting low levels of MRSA in food samples such as milk and orange juice, as well as in mouse serum, demonstrating greater sensitivity compared with real‐time PCR. This method holds significant potential application value in food detection and early diagnosis of pathogenic bacteria, highlighting its broad applicability. Methicillin‐resistant Staphylococcus aureus (MRSA) is a common and highly toxic bacterium in clinical practice. Herein, we developed a detection system (called “APC‐Cas‐PLNPs”) that can ultra‐sensitive detection for MRSA, using a nucleic acid‐based allosteric probe, CRISPR‐Cas12a, and dual‐colored persistent luminescent nanoparticles tandem detection. This method holds significant potential application value in food detection and early diagnosis of pathogenic bacteria, highlighting its broad applicability.

Actinobacteria are a group of ecologically important bacteria capable of producing diverse bioactive compounds. However, much remains unknown about the taxonomic and metabolic diversities of actinobacteria from many geographic regions and ecological niches. In this study, we report the isolation of actinobacteria from moss and moss-associated rhizosphere soils in Thailand. Among the 89 isolates analyzed for their bioactivities, 86 strains produced indole-3-acetic acid (IAA, ranging from 0.04 to 59.12 mg/L); 42 strains produced hydroxamate type of siderophore; 35 strains produced catecholate type of siderophore; 21 strains solubilized tricalcium phosphate; and many strains exhibited antagonistic activities against one to several of the seven selected plant, animal, and human pathogens. Overall, actinobacteria from the rhizosphere soil of mosses showed greater abilities to produce IAA and siderophores and to solubilize tricalcium phosphate than those from mosses. Among these 89 isolates, 37 were analyzed for their 16S rRNA gene sequences, which revealed their diverse phylogenetic distributions among seven genera, Streptomyces, Micromonospora, Nocardia, Actinoplanes, Saccharothrix, Streptosporangium, and Cryptosporangium. Furthermore, gas chromatography-mass spectrometry analyses of ethyl acetate crude extracts of three selected isolates with inhibitory effects against a methicillin-resistant Staphylococcus aureus strain revealed diverse metabolites with known antimicrobial activities. Together, our results demonstrate that actinobacteria from mosses in Thailand are taxonomically diverse and capable of producing a range of metabolites with plant-growth-promoting and microbial pathogen-inhibiting potentials.

Importance Regional clonal replacements of methicillin‐resistant Staphylococcus aureus (MRSA) are common. It is necessary to understand the clonal and drug resistance changes in specific areas. Objective To evaluate the clonal and drug resistance dynamics of MRSA in Chinese children from 2010 to 2017. Methods MRSA was isolated from patients in Beijing Children's Hospital from 2010 to 2013 and from 2016 to 2017. The molecular characteristics and antibiotic resistance were determined. Results In total, 211 MRSA isolates were collected, and 104 isolates were classified as community‐associated MRSA (CA‐MRSA). ST59‐SCCmec IV was the most prevalent type in both CA‐MRSA (65.4%) and healthcare‐ associated‐MRSA (HA‐MRSA) (46.7%). ST239‐SCCmec III accounted for 21.5% of all HA‐MRSA, which were not detected in 2016, and only three isolates were detected in 2017. The pvl gene carrying rate of CA‐ MRSA was significantly higher than that of HA‐MRSA (42.3% vs. 29.0%, P = 0.0456). Among CA‐MRSA, resistance rate to all tested antibiotics excluding chloramphenicol remained stable over the periods of 2010–2013 and 2016–2017. HA‐MRSA displayed an overall trend of decreased resistance to oxacillin, gentamicin, tetracycline, ciprofloxacin, and rifampin, and increased resistance to chloramphenicol, consistent with the difference of antibiotic resistance patterns between ST59‐SCCmec IV and ST239‐SCCmec III isolates. Vancomycin minimal inhibitory concentration (MIC) creep was found in the study period in all MRSA and ST59‐SCCmec IV isolates. Interpretation ST59‐SCCmec IV has spread to hospitals and replaced the traditional ST239‐SCCmec III clone, accompanied by changes in drug resistance. Furthermore, vancomycin MIC creep indicated that the rational use of antibiotics should be seriously considered.

Staphylococcus aureus (S. aureus) is a Gram-positive bacterium that may cause life-threatening diseases and some minor infections in living organisms. However, it shows notorious effects when it becomes resistant to antibiotics. Strain variants of bacteria, viruses, fungi, and parasites that have become resistant to existing multiple antimicrobials are termed as superbugs. Methicillin is a semisynthetic antibiotic drug that was used to inhibit staphylococci pathogens. The S. aureus resistant to methicillin is known as methicillin-resistant Staphylococcus aureus (MRSA), which became a superbug due to its defiant activity against the antibiotics and medications most commonly used to treat major and minor infections. Successful MRSA infection management involves rapid identification of the infected site, culture and susceptibility tests, evidence-based treatment, and appropriate preventive protocols. This review describes the clinical management of MRSA pathogenesis, recent developments in rapid diagnosis, and antimicrobial treatment choices for MRSA.

Difficult-to-treat infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are of concern in people living with HIV infection as they are more vulnerable to infection. We aimed to identify molecular characteristics of MRSA colonizing newly diagnosed HIV-infected adults in Tanzania. Individuals newly diagnosed with HIV infection were recruited in Dar es Salaam, Tanzania, from April 2017 to May 2018, as part of the randomized clinical trial CoTrimResist (ClinicalTrials.gov identifier: NCT03087890). Nasal/nasopharyngeal isolates of Staphylococcus aureus were susceptibility tested by disk diffusion method, and cefoxitin-resistant isolates were characterized by short-reads whole genome sequencing. Four percent (22/537) of patients carried MRSA in the nose/nasopharynx. MRSA isolates were frequently resistant towards gentamicin (95%), ciprofloxacin (91%), and erythromycin (82%) but less often towards trimethoprim-sulfamethoxazole (9%). Seventy-three percent had inducible clindamycin resistance. Erythromycin-resistant isolates harbored ermC (15/18) and LmrS (3/18) resistance genes. Ciprofloxacin resistance was mediated by mutations of the quinolone resistance-determining region (QRDR) sequence in the gyrA (S84L) and parC (S80Y) genes. All isolates belonged to the CC8 and ST8-SCCmecIV MRSA clone. Ninety-five percent of the MRSA isolates were spa-type t1476, and one exhibited spa-type t064. All isolates were negative for Panton-Valentine leucocidin (PVL) and arginine catabolic mobile element (ACME) type 1. All ST8-SCCmecIV-spa-t1476 MRSA clones from Tanzania were unrelated to the globally successful USA300 clone. Carriage of ST8 MRSA (non-USA300) was common among newly diagnosed HIV-infected adults in Tanzania. Frequent co-resistance to non-beta lactam antibiotics limits therapeutic options when infection occurs.

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a serious clinical threat, and D-Serine (D-Ser) showed significant sensitization effects on β-lactams against MRSA in our previous study. Quantitative PCR analysis found the elevated expression of the dlt operon with D-Ser combination, which is responsible for wall teichoic acid (WTA) modification involving D-Alanine (D-Ala). This study aims to verify the effect of D-Ser on WTA modification through the dlt pathway and explore the related effects on bacteria. The DltA and DltC were recombined, and enzyme kinetic evaluations with different D-amino acids were then conducted; it was found that D-Ser is the second-best substrate for DltA (just after D-Ala), no matter whether DltC is present or not. D-Ser treatment also lowered WTA generation as demonstrated by WTA phosphate quantification and native-PAGE electrophoresis, increased the susceptibility of S. aureus to polymyxins, and elevated the mouse survival rate in the MRSA intraperitoneal infection model without affecting the bacterial loads in the main organs, indicating possible effects of D-Ser on MRSA virulence through WTA modification. In conclusion, the current study provided evidence for D-Ser modification of WTA via the dlt pathway, and its possible involvement in D-Ser sensitization deserves further investigation.

Little is known about the expression of methicillin-resistant Staphylococcus aureus (MRSA) genes during infection conditions. Here, we described the transcriptome of the clinical MRSA strain USA300 derived from human cutaneous abscesses, and compared it with USA300 bacteria derived from infected kidneys in a mouse model. Remarkable similarity between the transcriptomes allowed us to identify genes encoding multiple proteases and toxins, and iron- and peptide-transporter molecules, which are upregulated in both infections and are likely important for establishment of infection. We also showed that disruption of the global transcriptional regulators agr and sae prevents in vivo upregulation of many toxins and proteases, protecting mice from lethal infection dose, and hinting at the role of these transcriptional regulators in the pathology of MRSA infection.