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Evaluating the methicillin resistance of Staphylococcus aureus (S. aureus) is highly important for adapting nursing strategies. Nevertheless, the identification of methicillin-resistant S. aureus (MRSA) that is both sensitive and reliable continues to pose a significant obstacle. This study describes a method for detecting MRSA using a combination of fixed rolling circle amplification (RCA) and the exonuclease-iii (Exo-iii) assisted CRISPR-Cas12a system for signal amplification. When MRSA is present, the interaction between the "b" chain in the capture probe and MRSA allows the "a" chain to be exposed. This "a" chain acts as a primer to initiate the fixed RCA process. The H probe, which includes the crRNA segment, forms a bond with the RCA product and then releases the crRNA segment with the aid of Exo-iii. The Cas12a protein, when combined with the crRNA, generates an activated CRISPR-Cas12a system that cleaves the "Reporter" probe, resulting in the production of fluorescent signals. Furthermore, this fluorescent test has been utilized for the examination of clinical samples with a satisfactory rate of retrieval. Based on the elegant design, the proposed method exhibited a low detection limit of 4.6 cfu/mL, while maintaining a high specificity for MRSA even from a mixture of several interfering bacteria. Due to its cost-effectiveness, simplicity, and adaptability, the sensing system shows potential as a platform for detecting MRSA and evaluating postoperative nursing for stomach cancer patients. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is the most important human pathogen, in community and hospital-acquired infections. The colonization rate of this organism is high in medical personnel and devices. Considering the importance of carriers in the transmission of S. aureus infection, this study investigated the origin of methicillin-resistant S. aureus (MRSA) isolated from Velayat and Poursina Hospitals of Rasht. In an eight-month period, a total of 500 samples were collected from hospitalized patients, healthcare personnel, various surfaces, air, and medical devices within the intensive care units (ICUs) of Velayat and Poursina Hospitals. After the identification of MRSA strains by microbiological and biochemical standard methods, the DNA of the isolates was extracted. The spa typing of MRSA strains was done after determining the sequence of amplified protein A genes by polymerase chain reaction (PCR) using specific primers. Among 500 samples, 45 (9%) samples were infected with S. aureus and 31 (68.9%) MRSA strains were identified from different ICUs. For the first time, S. aureus was divided into three types with the help of the spa technique in the ICU of Rasht hospitals. Among the examined samples, the t14870 spa type prevailed (95.5%), which had been found in previous studies in different regions of Iran. However, two types, t8463 (2.2%) and t605 (2.2%), were obtained for the first time in Iran, which were MRSA and obtained from the noses of patients. The high frequency of S. aureus isolates in (ICUs) and among healthcare personnel significantly contributes to the transmission of infections within the hospital setting. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) among milk pathogens is increasing, which is a serious threat to consumers’ health. Therefore, this study aims to assess the current antibiotic profile of coliforms and Staphylococcus spp. in milk samples. For this, thirty milk samples were collected from various locations in Kathmandu district. Isolation and enumeration were done on selective media using streak-plate and pour-plate techniques, respectively. Antibiotic susceptibility testing (AST) was done by the Kirby-Bauer disk diffusion method. A total of 48 bacteria were isolated, of which 31 were coliform and 17 Staphylococcus spp. Among the coliforms, Klebsiella spp. (n=17, 54.84%) was the most predominant in both raw (n=12, 70.6%) and pasteurized milk (n=5, 29.4%), followed by E. coli and Citrobacter spp. While for Staphylococcus spp., 15 (88.24%) were S. aureus and 2 (11.76%) were coagulase negative Staphylococcus (CONS). S. aureus was dominant in raw milk (n=13) rather than pasteurized milk (n=2). The AST of coliforms showed higher resistance towards ampicillin (96.75%), followed by cefoxitin, ciprofloxacin, nalidixic acid, nitrofurantoin, piperacillin, co-trimoxazole, ceftriaxone, chloramphenicol, and amikacin in descending order. In the case of S. aureus, higher resistance was observed for penicillin G (100.00%), followed by cefoxitin, ampicillin, ceftriaxone, tetracycline, ciprofloxacin, and amikacin. Further, 12 (70.53%) S. aureus were confirmed as methicillin-resistant S. aureus (MRSA). And a total of 10 (32.25%) coliforms and 9 (52.95%) S. aureus were identified as multiple drug resistant (MDR) strains. Thus, it can be concluded that antibiotic resistance among milk isolates of the coliform and Staphylococcus spp. is highly prevalent, and these can be a potential source of incurable milk-borne infections. Thus, routine assessment of microbial quality as well as AMR surveillance should be done on milk isolates to ensure the safety of consumer’s health. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) among milk pathogens is increasing, which is a serious threat to consumers’ health. Therefore, this study aims to assess the current antibiotic profile of coliforms and Staphylococcus spp. in milk samples. For this, thirty milk samples were collected from various locations in Kathmandu district. Isolation and enumeration were done on selective media using streak-plate and pour-plate techniques, respectively. Antibiotic susceptibility testing (AST) was done by the Kirby-Bauer disk diffusion method. A total of 48 bacteria were isolated, of which 31 were coliform and 17 Staphylococcus spp. Among the coliforms, Klebsiella spp. (n=17, 54.84%) was the most predominant in both raw (n=12, 70.6%) and pasteurized milk (n=5, 29.4%), followed by E. coli and Citrobacter spp. While for Staphylococcus spp., 15 (88.24%) were S. aureus and 2 (11.76%) were coagulase negative Staphylococcus (CONS). S. aureus was dominant in raw milk (n=13) rather than pasteurized milk (n=2). The AST of coliforms showed higher resistance towards ampicillin (96.75%), followed by cefoxitin, ciprofloxacin, nalidixic acid, nitrofurantoin, piperacillin, co-trimoxazole, ceftriaxone, chloramphenicol, and amikacin in descending order. In the case of S. aureus, higher resistance was observed for penicillin G (100.00%), followed by cefoxitin, ampicillin, ceftriaxone, tetracycline, ciprofloxacin, and amikacin. Further, 12 (70.53%) S. aureus were confirmed as methicillin-resistant S. aureus (MRSA). And a total of 10 (32.25%) coliforms and 9 (52.95%) S. aureus were identified as multiple drug resistant (MDR) strains. Thus, it can be concluded that antibiotic resistance among milk isolates of the coliform and Staphylococcus spp. is highly prevalent, and these can be a potential source of incurable milk-borne infections. Thus, routine assessment of microbial quality as well as AMR surveillance should be done on milk isolates to ensure the safety of consumer’s health.

Evaluating the methicillin resistance of Staphylococcus aureus (S. aureus) is highly important for adapting nursing strategies. Nevertheless, the identification of methicillin-resistant S. aureus (MRSA) that is both sensitive and reliable continues to pose a significant obstacle. This study describes a method for detecting MRSA using a combination of fixed rolling circle amplification (RCA) and the exonuclease-iii (Exo-iii) assisted CRISPR-Cas12a system for signal amplification. When MRSA is present, the interaction between the "b" chain in the capture probe and MRSA allows the "a" chain to be exposed. This "a" chain acts as a primer to initiate the fixed RCA process. The H probe, which includes the crRNA segment, forms a bond with the RCA product and then releases the crRNA segment with the aid of Exo-iii. The Cas12a protein, when combined with the crRNA, generates an activated CRISPR-Cas12a system that cleaves the "Reporter" probe, resulting in the production of fluorescent signals. Furthermore, this fluorescent test has been utilized for the examination of clinical samples with a satisfactory rate of retrieval. Based on the elegant design, the proposed method exhibited a low detection limit of 4.6 cfu/mL, while maintaining a high specificity for MRSA even from a mixture of several interfering bacteria. Due to its cost-effectiveness, simplicity, and adaptability, the sensing system shows potential as a platform for detecting MRSA and evaluating postoperative nursing for stomach cancer patients., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests. Ethical approval: This article does not contain any studies with human participants or animals performed by any of the authors. Consent to participate: Not applicable. Consent for publication: Not applicable., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Background & Objective: Methicillin-resistant Staphylococcus aureus (MRSA) is reported as one of the important bacterial causes of burn wound infections. This study was carried out to investigate molecular characterization of community-associated MRSA (CA-MRSA) isolated from Iranian burn patients. Methods: A total of 31 isolates of S. aureus were collected from the Motahari Burns Hospital (Tehran, Iran) in 2016. All isolates were collected from outpatients and inpatients within 48 hours of admission. The mecA, pvl, tsst-1, hla-α, and psmα genes detecting, SCCmec, agr and PFGE typing were done. Result: A total of 13 (41.9%) isolates were cefoxitin-resistant and mecA-positive, which were considered as MRSA. The SCCmec typing MRSA strains revealed type II in 1 (7.7%), type III in 9 (69.2%), and other types in 3 isolates (23.7%) cases. The agr typing of all 31 isolates showed that 14 (45.2%), 1 (3.2%), 6 (19.4%), and 10 (32.3%) strains belonged to agr groups 1, 3, 4, and unknown type, respectively. The pvl, tsst-1, hla-α, and psmα genes were positive in 3 (9.7%), 4 (12.9%), 21 (67.7%), and 31 (100%) isolates, respectively. Considering the cut-off values of ≥50%, 3 groups of related isolates (cluster A1, B1, and C1) in PFGE study were observed. Conclusion: The MRSA strains of this study were initially isolated as Community-associated S. aureus (CA-MRSA); however molecular characterization showed that a significant proportion of them had hospital-associated MRSA (HA-MRSA) features. Therefore, it is likely that the HA-MRSA strains are spread among the community.

Staphylococcus aureus is a commensal organism in approximately 30% of the human population and colonization is a significant risk factor for invasive infection. As a result of this, there is a great need to better understand how S. aureus overcomes human immunity. Neutrophils are essential during the innate immune response to S. aureus, yet this microorganism uses multiple evasion strategies to avoid killing by these immune cells, perhaps the most catastrophic of which is the rapid induction of neutrophil cell death. The aim of this study was to better understand the mechanisms underpinning S. aureus-induced neutrophil lysis, and how this contributes to pathogenesis in a whole organism model of infection. To do this we screened the genome-wide Nebraska Transposon Mutant Library (NTML) in the community acquired methicillin resistant S. aureus strain, USA300, for decreased ability to induce neutrophil cell lysis. Out of 1,920 S. aureus mutants, a number of known regulators of cell lysis (including the master regulators accessory gene regulator A, agrA and Staphylococcus exoprotein expression protein S, saeS) were identified in this blinded screen, providing validity to the experimental system. Three gene mutations not previously associated with cell death: purB, lspA, and clpP were found to be significantly attenuated in their ability to induce neutrophil lysis. These phenotypes were verified by genetic transductants and complemented strains. purB and clpP were subsequently found to be necessary for bacterial replication and pathogenesis in a zebrafish embryo infection model. The virulence of the clpP mutant was restored in a neutrophil-depleted zebrafish model, suggesting the importance of ClpP in mechanisms underpinning neutrophil immunity to S. aureus. In conclusion, our work identifies genetic components underpinning S. aureus pathogenesis, and may provide insight into how this commensal organism breaches innate immune barriers during infection.

Staphylococcus aureus is a commensal organism in approximately 30% of the human population and colonization is a significant risk factor for invasive infection. As a result of this, there is a great need to better understand how S. aureus overcomes human immunity. Neutrophils are essential during the innate immune response to S. aureus , yet this microorganism uses multiple evasion strategies to avoid killing by these immune cells, perhaps the most catastrophic of which is the rapid induction of neutrophil cell death. The aim of this study was to better understand the mechanisms underpinning S. aureus- induced neutrophil lysis, and how this contributes to pathogenesis in a whole organism model of infection. To do this we screened the genome-wide Nebraska Transposon Mutant Library (NTML) in the community acquired methicillin resistant S. aureus strain, USA300, for decreased ability to induce neutrophil cell lysis. Out of 1,920 S. aureus mutants, a number of known regulators of cell lysis (including the master regulators accessory gene regulator A, agrA and Staphylococcus exoprotein expression protein S, saeS) were identified in this blinded screen, providing validity to the experimental system. Three gene mutations not previously associated with cell death: purB, lspA , and clpP were found to be significantly attenuated in their ability to induce neutrophil lysis. These phenotypes were verified by genetic transductants and complemented strains. purB and clpP were subsequently found to be necessary for bacterial replication and pathogenesis in a zebrafish embryo infection model. The virulence of the clpP mutant was restored in a neutrophil-depleted zebrafish model, suggesting the importance of ClpP in mechanisms underpinning neutrophil immunity to S. aureus. In conclusion, our work identifies genetic components underpinning S. aureus pathogenesis, and may provide insight into how this commensal organism breaches innate immune barriers during infection. [ABSTRACT FROM AUTHOR]