Methicillin-resistant Staphylococcus Aureus Control Research Articles

Evaluation of the Anti-MRSA Activity of Supercritical Carbon Dioxide and Macerated Crude Extracts of Padina spp. Collected from the Coastal Waters of Tacloban City, the Philippines

The World Health Organization classifies methicillin-resistant Staphylococcus aureus (MRSA) as a high priority in the pathogens list for research and development of new antibiotics. Natural compounds from brown algae are being studied for their potential as alternative sources of antibiotics, including Padina spp. This study aims to evaluate the anti-MRSA activity of the crude extracts obtained through supercritical carbon dioxide extraction (SCCO2) and maceration (MAC) of Padina spp. seaweeds from the coastal waters of Tacloban City, the Philippines. The evaluation of extracts for their anti-MRSA and anti-MSSA (methicillin-susceptible Staphylococcus aureus) activities was done via the resazurin microplate assay, and the Mann-Whitney U test was used to compare these activities. Results show that MAC exhibited minimum inhibitory concentrations (MIC) of 2,048–4,096 μg/mL and 512–4,096 μg/mL for SCCO2 for the MRSA and MSSA control and clinical isolates, respectively. While the MICs for the SCCO2 extracts were lower than those for the MAC extracts, no significant difference was found between the MICs of the extracts from the two extraction methods. No significant difference was observed between the MICs of the extracts against the MRSA (43300) and MSSA (25923) ATCC strains and clinical isolates. Finally, significant differences were observed between the MICs of the control antibiotics and both extraction methods.

Isolation and encapsulation of bacteriophage with chitosan nanoparticles for biocontrol of multidrug-resistant methicillin-resistant Staphylococcus aureus isolated from broiler poultry farms

This study was divided into two parts. The first part, the determination of methicillin-resistant Staphylococcus aureus (MRSA) prevalence in 25 broiler chicken farms, with the detection of multidrug resistant MRSA strains. The prevalence of MRSA was 31.8% (159 out of 500 samples) at the level of birds and it was 27% (27 out of 100) in the environmental samples. The highest antimicrobial resistance of the recovered MRSA strains was recorded to streptomycin (96%). All isolates (100%) had multidrug resistance (MDR) to four or more antibiotics with 16 distinct antibiotic resistant patterns, and multiple antibiotic resistance index (MARI) of 0.4–1. The second part, implementing novel biocontrol method for the isolated multidrug resistant MRSA strains through the isolation of its specific phage and detection of its survival rate at different pH and temperature degrees and lytic activity with and without encapsulation by chitosan nanoparticles (CS-NPs). Encapsulated and non-encapsulated MRSA phages were characterized using transmission electron microscope (TEM). Encapsulation of MRSA phage with CS-NPs increasing its lytic activity and its resistance to adverse conditions from pH and temperature. The findings of this study suggested that CS-NPs act as a protective barrier for MRSA phage for the control of multidrug resistant MRSA in broiler chicken farms.

Photobiomodulation and conditioned medium of adipose-derived stem cells for enhancing wound healing in rats with diabetes: an investigation on the proliferation phase.

This investigation tried to evaluate the combined and solo effects of photobiomodulation (PBM) and conditioned medium derived from human adipose tissue-derived stem cells (h-ASC-CM) on the inflammatory and proliferative phases of an ischemic infected delayed healing wound model (IIDHWM) in rats with type I diabetes mellitus (TIDM). The present investigation consisted of four groups: group 1 served as the control, group 2 treated with h-ASC-CM, group 3 underwent PBM treatment, and group 4 received a combination of h-ASC-CM and PBM. Clinical and laboratory assessments were conducted on days 4 and 8. All treatment groups exhibited significantly higher wound strength than the group 1 (p = 0.000). Groups 4 and 3 demonstrated significantly greater wound strength than group 2 (p = 0.000). Additionally, all therapeutic groups showed reduced methicillin -resistant Staphylococcus aureus (MRSA) in comparison with group 1 (p = 0.000). While inflammatory reactions, including neutrophil and macrophage counts, were significantly lower in all therapeutic groups rather than group 1 on days 4 and 8 (p < 0.01), groups 4 and 3 exhibited superior results compared to group 2 (p < 0.01). Furthermore, proliferative activities, including fibroblast and new vessel counts, as well as the measurement of new epidermal and dermal layers, were significantly increased in all treatment groups on 4 and 8 days after the surgery (p < 0.001). At the same times, groups 4 and 3 displayed significantly higher proliferative activities compared to group 2 (p < 0.001). The treatment groups exhibited significantly higher mast cell counts and degranulation phenotypes in comparison with the group 1 on day 4 (p < 0.05). The treatment groups showed significantly lower mast cell counts and degranulation phenotypes than group 1 on day 8 (p < 0.05).The combined and individual application of h-ASC-CM and PBM remarkably could accelerate the proliferation phase of wound healing in the IIDHWM for TIDM in rats, as indicated by improved MRSA control, wound strength, and stereological evaluation. Furthermore, the combination of h-ASC-CM and PBM demonstrated better outcomes compared to the individual application of either h-ASC-CM or PBM alone.

The Prevalence, Epidemiological, and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus (MRSA) in Macau (2017-2022).

Macau, recognized as a global tourism hub and the world's most densely populated region, provides a unique environment conducive to methicillin-resistant Staphylococcus aureus (MRSA) transmission in healthcare and community settings, posing a significant public health concern both locally and globally. The epidemiology and molecular characteristics of MRSA in the distinct city of Macau remain largely unelucidated. This five-year longitudinal study (2017-2022) examined the local prevalence and molecular typing of MRSA in Macau, with future MRSA type distribution predicted through ARIMA modeling. We subsequently analyzed the epidemiological characteristics of MRSA, including specimen source, clinical department, collection year, season, patient age, sex, and the annual number of tourists. Comprehensive antibiotic resistance profiles of the strains were also assessed. Of 504 clinically isolated S. aureus strains, 183 (36.3%) were identified as MRSA by the cefoxitin disk diffusion method and validated through multi-locus sequence typing (MLST). The MRSA detection rate showed an upward trend, increasing from 30.1% in 2017 to 45.7% in 2022. SCCmec type IV was predominant (28.9%), followed by types II (25.4%), III (22.1%), and V (22.1%). The primary sources of MRSA isolates were sputum (39.2%) and secretions (25.6%). Older age emerged as a risk factor for MRSA infection, whereas no significant associations were found with seasonal variations, gender, or the annual number of tourists. Despite displaying universal resistance to cefoxitin, oxacillin, and benzylpenicillin, MRSA isolates in Macau remained fully sensitive to vancomycin, tigecycline, quinupristin, nitrofurantoin, and linezolid. Continuous surveillance and analysis of MRSA distribution in Macau could provide invaluable insights for the effective management of MRSA prevention and control measures within healthcare settings.

Dielectrophoresis microbial characterization and isolation of Staphylococcus aureus based on optimum crossover frequency.

Characterization of antibiotic-resistant bacteria is a significant concern that persists for the rapid classification and analysis of the bacteria. A technology that utilizes the manipulation of antibiotic-resistant bacteria is key to solving the significant threat of these pathogenic bacteria by rapid characterization profile. Dielectrophoresis (DEP) can differentiate between antibiotic-resistant and susceptible bacteria based on their physical structure and polarization properties. In this work, the DEP response of two Gram-positive bacteria, namely, Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-susceptible S. aureus (MSSA), was investigated and simulated. The DEP characterization was experimentally observed on the bacteria influenced by oxacillin and vancomycin antibiotics. MSSA control without antibiotics has crossover frequencies ( ) from 6 to 8MHz, whereas MRSA control is from 2 to 3MHz. The changed when bacteria were exposed to the antibiotic. As for MSSA, the decreased to 3.35MHz compared to MSSA control without antibiotics, MRSA, increased to 7MHz when compared to MRSA control. The changes in the DEP response of MSSA and MRSA with and without antibiotics were theoretically proven using MyDEP and COMSOL simulation and experimentally based on the modification to the bacteria cell walls. Thus, the DEP response can be employed as a label-free detectable method to sense and differentiate between resistant and susceptible strains with different antibiotic profiles. The developed method can be implemented on a single platform to analyze and identify bacteria for rapid, scalable, and accurate characterization.

Insights into the Effects and Mechanism of Andrographolide-Mediated Recovery of Susceptibility of Methicillin-Resistant Staphylococcus aureus to β-Lactam Antibiotics.

The frequent resistance associated with β-lactam antibiotics and the high frequency of mutations in β-lactamases constitute a major clinical challenge that can no longer be ignored. Andrographolide (AP), a natural active compound, has been shown to restore susceptibility to β-lactam antibiotics. Fluorescence quenching and molecular simulation showed that AP quenched the intrinsic fluorescence of β-lactamase BlaZ and stably bound to the residues in the catalytic cavity of BlaZ. Of note, AP was found to reduce the stability of the cell wall (CW) in methicillin-resistant Staphylococcus aureus (MRSA), and in combination with penicillin G (PEN), it significantly induced CW roughness and dispersion and even caused its disintegration, while the same concentration of PEN did not. In addition, transcriptome sequencing revealed that AP induced a significant stress response and increased peptidoglycan (PG) synthesis but disrupted its cross-linking, and it repressed the expression of critical genes such as mecA, blaZ, and sarA. We also validated these findings by quantitative reverse transcription-PCR (qRT-PCR). Association analysis using the GEO database showed that the alterations caused by AP were similar to those caused by mutations in the sarA gene. In summary, AP was able to restore the susceptibility of MRSA to β-lactam antibiotics, mainly by inhibiting the β-lactamase BlaZ, by downregulating the expression of critical resistance genes such as mecA and blaZ, and by disrupting CW homeostasis. In addition, restoration of susceptibility to antibiotics could be achieved by inhibiting the global regulator SarA, providing an effective solution to alleviate the problem of bacterial resistance. IMPORTANCE Increasingly, alternatives to antibiotics are being used to mitigate the rapid onset and development of bacterial resistance, and the combination of natural compounds with traditional antibiotics has become an effective therapeutic strategy. Therefore, we attempted to discover more mechanisms to restore susceptibility and effective dosing strategies. Andrographolide (AP), as a natural active ingredient, can mediate recovery of susceptibility of MRSA to β-lactam antibiotics. AP bound stably to the β-lactamase BlaZ and impaired its hydrolytic activity. Notably, AP was able to downregulate the expression of critical resistance genes such as mecA, blaZ, and sarA. Meanwhile, it disrupted the CW cross-linking and homeostasis, while the same concentration of penicillin could not. The multiple inhibitory effect of AP resensitizes intrinsically resistant bacteria to β-lactam antibiotics, effectively prolonging the use cycle of these antibiotics and providing an effective solution to reduce the dosage of antibiotics and providing a theoretical reference for the prevention and control of MRSA.

Polymeric nano-system for macrophage reprogramming and intracellular MRSA eradication.

Intracellular Methicillin-Resistant Staphylococcus aureus (MRSA) remains a major factor of refractory and recurrent infections, which cannot be well addressed by antibiotic therapy. Here, we design a cellular infectious microenvironment-activatable polymeric nano-system to mediate targeted intracellular drug delivery for macrophage reprogramming and intracellular MRSA eradication. The polymeric nano-system is composed of a ferrocene-decorated polymeric nanovesicle formulated from poly(ferrocenemethyl methacrylate)-block-poly(2-methacryloyloxyethyl phosphorylcholine) (PFMMA-b-PMPC) copolymer with co-encapsulation of clofazimine (CFZ) and interferon-γ (IFN-γ). The cellular-targeting PMPC motifs render specific internalization by macrophages and allow efficient intracellular accumulation. Following the internalization, the ferrocene-derived polymer backbone sequentially undergoes hydrophobic-to-hydrophilic transition, charge reversal and Fe release in response to intracellular hydrogen peroxide over-produced upon infection, eventually triggering endosomal escape and on-site cytosolic drug delivery. The released IFN-γ reverses the immunosuppressive status of infected macrophages by reprogramming anti-inflammatory M2 to pro-inflammatory M1 phenotype. Meanwhile, intracellular Fe2+-mediated Fenton reaction together with antibiotic CFZ contributes to increased intracellular hydroxyl radical (•OH) generation. Ultimately, the nano-system achieves robust potency in ablating intracellular MRSA and antibiotic-tolerant persisters by synchronous immune modulation and efficient •OH killing, providing an innovative train of thought for intracellular MRSA control.

Phenotypic and genotypic profiling reveals a high prevalence of methicillin-resistant Staphylococcus aureus isolated from hospitals, houseflies and adjacent informal food retailers in Botswana.

The increasing occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in the environment, food and healthcare systems is a global public health concern. MRSA is reported to cause food poisoning, osteomyelitis and pyogenic infections of the skin, and consequently has been categorized as a high-priority pathogen by the World Health Organization. Here, we determined the presence of MRSA in clinical (n=56), food (n=150) and housefly samples (n=970) collected from two hospitals in Botswana. Characterization based on phenotypic (antimicrobial resistance, biofilm production) and genotypic (antimicrobial resistance genes and integrons) profiles were performed on all isolates. Of the total samples tested, 64 were positive for MRSA following conventional culture methods and PCR amplification of the mecA and mecC genes for confirmation of presumptive MRSA isolates. The confirmed isolates included 71 % (95 % CI 83.2-59.6) from clinical, 9 % (95 % CI 14--4.8) from food, and 1 % (95 % CI 1.6-0.4) collected from housefly samples. In total 89 % (n=57) isolates in the current study showed a multidrug resistance phenotype, among these, resistance to β-lactams and glycoside antibiotic classes were predominant. Genotypic characterization showed the domination of the blatem gene (95 %) followed by fox (63 %) and tetO (19 %) whilst vanA was only reported in 13 % of the isolates. Integrons were detected in 50 % (32/64) of the total MRSA isolates, and we report a high prevalence of etd gene, detected in 67 % (43/64) of the isolates followed by eta 38 % (24/64) whilst tsst-1 (3%) was the least detected genetic determinant. The genes etb and PVL were not detected in a ll the tested MRSA isolates. We provide the first report on the prevalence of MRSA isolated from the clinical-food-vector nexus harbouring biofilm and blatem genes, and antibiotic resistance profiles in Botswana. These results are significant for risk-assessment analysis and the development of improved MRSA infection prevention and control strategies.

Methicillin-resistant staphylococcus aureus nosocomial infection has a distinct epidemiological position and acts as a marker for overall hospital-acquired infection trends

An ongoing healthcare debate is whether controlling hospital-acquired infection (HAI) from methicillin-resistant Staphylococcus aureus (MRSA) will result in lowering the global HAI rate, or if MRSA will simply be replaced by another pathogen and there will be no change in overall disease burden. With surges in drug-resistant hospital-acquired pathogens during the COVID-19 pandemic, this remains an important issue. Using a dataset of more than 1 million patients in 51 acute care facilities across the USA, and with the aid of a threshold model that models the nonlinearity in outbreaks of diseases, we show that MRSA is additive to the total burden of HAI, with a distinct ‘epidemiological position’, and does not simply replace other microbes causing HAI. Critically, as MRSA is reduced it is not replaced by another pathogen(s) but rather lowers the overall HAI burden. The analysis also shows that control of MRSA is a benchmark for how well all non-S. aureus nosocomial infections in the same hospital are prevented. Our results are highly relevant to healthcare epidemiologists and policy makers when assessing the impact of MRSA on hospitalized patients. These findings further stress the major importance of MRSA as a unique cause of nosocomial infections, as well as its pivotal role as a biomarker in demonstrating the measured efficacy (or lack thereof) of an organization’s Infection Control program.

Considering the precautionary principle and its application to MRSA and SARS-CoV-2 as emerging novel pathogens of their time.

In the 1980s Contact Precautions were introduced as a precautionary measure to control the emerging threat of antimicrobial resistance in hospitals, particularly methicillin resistant Staphylococcus aureus (MRSA). Today, antimicrobial resistance remains a concerning global public health threat, and a focus for hospital patient safety priorities. In late 2019 a novel respiratory virus described as SARS-CoV-2, was reported. Just as MRSA had prompted control measures developed in the context of limited information and understanding of the pathogen, public health control measures against SARS-CoV-2 were promptly and strictly implemented. Whilst SARS-CoV-2 control measures were successful at containing the virus, numerous detrimental socio-economic and health impacts have led to a rebalancing of harms versus benefits and loosening of restrictions. Conversely, evidence collated over the past 50 years, suggests that Contact Precautions are not superior to well-applied standard infection prevention and control precautions in controlling MRSA acquisition in hospitals. Several harms associated with Contact Precautions, affecting patient safety, financial costs, and organisational culture, are described. However, rebalancing of hospital MRSA control policies has been slow to materialise. This commentary invites infection prevention and control policy makers to reflect and revise policies for the control of MRSA in hospitals so that harms do not outweigh benefits.

Educational Intervention to Improve adherence to Methicillin-Resistant Staphylococcus Aureus Control Practice Among Nurses at Two Hospitals in Egypt

Purpose: The aim of this study was to evaluate the effectiveness of an educational intervention to improve adherence to Methicillin-Resistant Staphylococcus Aureus control practice among nurses at two Hospitals in Egypt. Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen and the most common multidrug-resistant bacterium which is responsible for nosocomial infections, with elevated morbidity and mortality rate. Nurses need a comprehensive intervention to improve adherence to MRSA control practice in order to decrease the rate of its spread.&#x0D; Research design: Pre /post-quasi-experimental design was used in this study. This study was carried out at two hospitals in Egypt (Mansoura Chest Disease and Benha University Hospital). A convenient sample of 80 nurses. Tool I- Nurses’s Structured Interview Questionnaire in Arabic language. Tool II - Observational Checklist for MRSA and Infection Control Practice. Descriptive statistics such as frequencies, means, and standard deviations were used to summarize the data. Chi-square and r (correlation) were used to correlate between the studied variables.&#x0D; Methodology: Before the application of educational intervention 32.5% of nurses has poor practice levels and the percentage decreased to 7.5%, 14.5 immediately and 2 months post-educational intervention respectively.&#x0D; Unique contribution to theory, practice and policy: The educational intervention was effective in improving adherence to Methicillin-Resistant Staphylococcus Aureus control practice among nurses at the two hospitals as there is a statistically significant difference between all phases of the study regarding nurses' practice. Emphasizing the importance of following the latest updated evidence-based approaches to infection control in continuing training programs, and infection prevention with national guidelines (standard precautions) should be provided.

THE GLOBAL SPREAD AND EPIDEMIOLOGICAL CHARACTERISTICS OF SALMONELLA SPP, ESCHERICHIA COLI AND METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA):RELATED RESEARACH STUDIES IN SERBIA

It has been established that some clones of pathogenic bacteria such as Salmonella spp., Escherichia coli ST131, and methicillin-resistant Staphylococcus aureus (MRSA) tend to spread worldwide. Therefore, epidemiological surveys have been conducted to identify the source of infection and to break the chain of infection. In this article, it was pointed out that common international clones of Salmonella are represented with the serotypes Typhimurium, Kentucky, Infantis and Enteritidis. Serovars Typhimurium and Kentucky display multidrug-resistant phenotypes more frequently. Several sequence types of E. coli and the international clone ST131 are described, including clades C1 and C2 with the extended-spectrum cephalosporin-resistance genes (blaCTX-M-15 or blaCTX-M-27). These pathogens are often found in both humans and animals. It is noted that Staphylococcus aureus became resistant to methicillin almost instantly after its introduction into clinical practice. Soon afterwards, MRSA found its way to farm animals and wildlife. The cycles of infection are bidirectional: humans can disseminate MRSA in the environment but animals may also be sources of infection for humans. Comprehensive work has been done by epidemiologists to introduce all necessary measures to eliminate MRSA from hospitals. Also, much effort has been made in MRSA control to prevent infections on animal farms and contamination in the primary food production chain. As the struggle with pathogenic bacteria continues, we face the incessant threat of new resistance and virulence mechanisms, which bacteria use to resist the hostile environment and enhance their survival in their natural habitats including humans and animals. Therefore, the capacity of certain bacteria to spread due to their virulence mechanisms and resistance phenotypes is presented, and a brief description of the research conducted in Serbia is included.

Potentiation of β-Lactams against Methicillin-Resistant Staphylococcus aureus (MRSA) Using Octyl Gallate, a Food-Grade Antioxidant.

Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to a number of antibiotics of clinical importance and is a serious threat to public health. Since bacteria rapidly develop resistance even to newly discovered antibiotics, this study aimed to develop drug potentiators to enhance the antibacterial activity of existing antibiotics for the control of MRSA. Based on our previous studies, screening of antimicrobial synergy was conducted with gallic acid and its derivatives using checkerboard assays. Antimicrobial synergy was confirmed with MRSA isolates from clinical cases. Combinations of penicillin, ampicillin, and cephalothin with octyl gallate (OG), an antioxidant approved by the US Food and Drug Administration (FDA), consistently exhibited synergistic bacteriostatic and bactericidal activities against MRSA, rendering MRSA sensitive to β-lactams. The fractional inhibitory concentration (FIC) and fractional bactericidal concentration (FBC) indices exhibited that the antimicrobial effects of OG were synergistic. The results of a permeability assay showed that OG significantly increased the permeability of the bacterial cell wall. Despite the intrinsic resistance of MRSA to β-lactams, the findings in this study demonstrated that OG enhanced the activity of β-lactams in MRSA and sensitized MRSA to β-lactams, suggesting that OG can be used as a drug potentiator to control MRSA using existing antibiotics.

Prevalence of Mastitis and Phenotypic Characterization of Methicillin-Resistant Staphylococcus aureus in Lactating Dairy Cows of Selected Dairy Farms in and Around Adama Town, Central Ethiopia.

Background:The emergence of Methicillin resistant Staphylococcus aureus (MRSA) poses a serious public health threat. Strains of Staphylococcus aureus resistant to β-lactam antibiotics are known as MRSA. MRSA has gained attention as community pathogen. MRSA has been increasingly reported as emerging problem in veterinary medicine. However, little is known in Ethiopia. This study was, therefore, conducted to identify MRSA, to determine its drug susceptibility patterns, and mastitis infection in dairy cattle in and around Adama town, Central Ethiopia.Methods:A cross-sectional study was conducted to estimate the occurrence of MRSA in mastitic dairy cows in and around Adama town, central Ethiopia. A total of 384 lactating cows were included from the conveniently selected dairy farms in the study area. Approximately 10 ml of milk was aseptically collected from clinical and subclinical mastitic cows into sterile universal bottles after discarding the first 3 milking streams. Then, Staphylococcus aureus was isolated using the conventional bacteriological procedure. Resistance to methicillin was detected using the Kirby-Bauer disc diffusion antibiotic susceptibility method. Oxacillin disc was used to detect methicillin resistant Staphylococcus aureus strains. Antimicrobial susceptibility test was conducted against MRSA strains using streptomycin (S, 10 µg), amoxicillin (Am, 25 µg), kanamycin (k, 30 µg), nalidixic acid (NA, 30 µg), oxytetracycline (OT, 30 µg) sulphonamide (S, 300 µg) and ceftriazole (CRO, 30 µg).Results:The study found that the prevalence of mastitis was 121(31.5%). Among this 37(30.6%) were clinical mastitis and 84 (69.4%) of them were sub-clinical mastitis. Of 121 mastitis cases, Staphylococcus aureus was isolated in 37 (30.6%) of mastitic cow milk samples. The prevalence of mastitis was significantly affected by breed, age, floor type and hygienic status of the milkers (P < .05). Moreover, 32.4% of Staphylococcus aureus isolates were resistant to oxacillin. A total of 75% percent of MRSA isolates were resistant to amoxicillin, 66.7% were resistant to oxytetracycline, and 50% were resistant to sulphonamide. However, 75% of MRSA isolates were susceptible to kanamycin, 58.3% were susceptible to streptomycin, and 50% were susceptible to nalidixic acid.Conclusion:The study revealed that relatively high number of strains are resistant to the antibiotics commonly used in the therapeutic protocol of many human and animal infections. Therefore, antimicrobial susceptibility test should be carried out at a regular basis and proper hygienic practices should be introduced at farm level. Creating public awareness about transmission, prevention and control of MRSA should also be considered.

Sulfamethoxazole-phytochemical hybrid: A novel approach in current antibacterial drug development

Background: The Gram-positive (GP) bacterium, methicillin-resistant Staphylococcus aureus (MRSA) causes common infection, bacteremia at hospitals, and community sectors, with the simultaneous aggrandizement of resistance to several currently used antibacterials, resulting in additional morbidity and unexpected mortality. Since the last several decades, thousands of phytochemicals with antimicrobial potency have been recorded as alternate antibacterial agents; but, none of those have gone up to the pure-drug stage due to the lack of the desired drug-likeness values and the required pharmacokinetic properties. However, chemical modification of parent drug remains as the versatile approach in antibacterial drug development. Methods and materials: Based on the structural suitability of sulfamethoxazole (SMZ) and as a solution towards control of MRSA, proposed six new ‘SMZ-phytochemical’ hybrid entities followed by protocol of azo-coupling synthesis. PASS prediction, Lipinski rules of five, lethal-dose value, toxicity class, and molecular docking-simulation were employed before chemical synthesis. Due to the unavailability of the three-dimensional (3D) structure of the suitable target enzyme, MRSA-dihydropteroate synthases (DHPS), the 3D model of MRSA-DHPS was generated and validated by the Ramachandran plot for molecular docking-simulations study with designed hybrids. Based on the above computational analyses, the most effective hybrid, ‘SMZ-thymol,’ was synthesized and characterized by advanced spectral techniques such as UV, FTIR, LCMS, HPLC, NMR, and SEM. The zone of inhibition, MIC, and MBC values of the hybrid had determined against isolated MRSA strain from clinical samples, in vitro. Results: The synthesized ‘SMZ-thymol’ hybrid had the highest zone size inhibition on agar plates with 20 and 40 μg/mL as the lowest MIC and MBC values against MRSA, respectively, while the reference antibiotic ampicillin had the lower MIC and MBC values at 80 to 180 μg/mL. Additionally, from in vitro host-toxicity testing with cultured human lymphocytes from umbilical cord blood confirmed that the synthesized hybrid had broadly, non-toxic to human cells. Conclusion: Thus, newly synthesized ‘SMZ-thymol’ could be promoted as a newer antibacterial agent against gruesome MRSA and other MDR pathogenic bacteria. Indeed, the utilization of inactive antibacterials through suitable phytochemicals in the current antibacterial drug development module could be a prudent time-killing drug development approach using tools of medicinal chemistry and bioinformatics.

Occupational risk of exposure to methicillin-resistant Staphylococcus aureus (MRSA) and the quality of infection hygiene in nursing homes

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing health concern across the globe and is often prevalent at long-term care facilities, such as nursing homes. However, we know little of whether nursing home staff is exposed to MRSA via air and surfaces. We investigated whether staff members at nursing homes are colonised with and exposed to culturable MRSA, and assessed staff members’ self-reported knowledge of MRSA and compliance with infection hygiene guidelines. Five nursing homes with MRSA positive residents were visited in Copenhagen, Denmark. Personal bioaerosol exposure samples and environmental samples from surfaces, sedimented dust and bioaerosols were examined for MRSA and methicillin-susceptible S. aureus (MSSA) to determine occupational exposure. Swabs were taken from staffs’ nose, throat, and hands to determine whether they were colonised with MRSA. An online questionnaire about MRSA and infection control was distributed. No staff members were colonised with MRSA, but MRSA was detected in the rooms of the colonised residents in two out of the five nursing homes. MRSA was observed in air (n =4 out of 42, ranging from 2.9–7.9 CFU/m3), sedimented dust (n = 1 out of 58, 1.1 × 103 CFU/m2/d), and on surfaces (n = 9 out of 113, 0.04–70.8 CFU/m2). The questionnaire revealed that half of the staff members worry about spreading MRSA to others. Identified aspects for improvement were improved availability and use of protective equipment, not transferring cleaning supplies (e.g., vacuum cleaners) between residents’ rooms and to reduce worry of MRSA, e.g., through education.

Formulation and evaluation of anti-MRSA nanoemulsion loaded with Achyrocline satureioides: a new sustainable strategy for the bovine mastitis

Methicillin-resistant Staphylococcus aureus (MRSA) causes mastitis in dairy cattle with serious economic and public health significance. This study developed nanoemulsions of Linum usitatissimun oil loaded with Achyrocline satureioides (macela) extract and investigated their in vitro antimicrobial activity against MRSA. Macela-nanoemulsions (NE-ML) were prepared using high-pressure homogenization (HPH) with different proportions of flaxseed oil, Tween 80 and crude extract. Four majoritarian flavonoids were identified in the macela extract: 3-O methylquercetin, achyrobichalcone, quercetin and luteolin (187.3 ± 0.1, 155.4 ± 11.6, 76.3 ± 0.1 and 30.4 ± 0.0 μg ml−1, respectively). NE-ML nanoemulsions were successfully obtained by the HPH method and showed a milky aspect with yellowish color. The mean particle size was around 200 nm with monodisperse distribution (PdI < 0.2), remaining stable for 160 days at room temperature. When analyzed on a LUMiSizer high-end dispersion analyzer, low values were found (≤0.5), indicating high stability index, mainly for NE-ML1:5 (0.2). The encapsulation efficiency of macela-nanoemulsions was greater than 94%, considering the four chemical compounds from extract. Minimum inhibitory concentration (MIC) against planktonic bacteria, inhibition of biofilm formation (MBIC), and eradication of MRSA biofilms (MBEC) were determined through in vitro tests on microplates. The MIC of NE-ML against planktonic MRSA showed values ranging from 1.2 to 10% (v/v), while blank-nanoemulsions (NE-B, without macela extract) showed values ranging from 6 to 50% (v/v). MBIC and MBEC of NE-ML were 25 and 80% (v/v), respectively. MBIC showed a mass reduction greater than 64%, and MBEC showed a mass reduction greater than 73%. Macela-nanoemulsions (NE-ML), mainly NE-ML1:5, showed high antimicrobial activity and appeared to represent a new alternative of sustainable antimicrobial product for the control of MRSA. Since this innovative nanoemulsion can impact animal health, future research should include in vitro and in vivo studies to evaluate intramammary therapy and control of MRSA infections in organic and agroecological milk production systems.

Acquisition Risk Factors of the SCCmec IX-Methicillin-Resistant Staphylococcus aureus in Swine Production Personnel in Chiang Mai and Lamphun Provinces, Thailand.

Methicillin-resistant Staphylococcus aureus (MRSA) harboring the type-IX staphylococcal cassette chromosome mec (SCCmec) has been found in pigs and humans in Northern Thailand. However, knowledge of the prevalence and acquisition risk factors of this MRSA strain among swine production personnel (SPP) are needed. The nasal swab samples and data were collected from 202 voluntary SPP and 31 swine farms in Chiang Mai and Lamphun Provinces, Thailand in 2017. MRSA were screened and identified using mannitol salt agar, biochemical and antimicrobial susceptibility testing, multiplex PCR, and the SCCmec typing. The prevalence of MRSA was 7.9% (16/202) and 19.3% (6/31) among SPP and swine farms. All isolates were multidrug-resistant, and 55 of 59 isolates (93%) contained the type-IX SCCmec element. Data analysis indicated that education, working time, contact frequency, working solely with swine production, and personal hygiene were significantly related to MRSA acquisition (p < 0.05). The multivariate analysis revealed that pig farming experience, working days, and showering were good predictors for MRSA carriage among SPP (area under the curve (AUC) = 0.84). The biosecurity protocols and tetracycline use were significantly associated with MRSA detection in pig farms (p < 0.05). Hence, the active surveillance of MRSA and further development of local/national intervention for MRSA control are essential.

Genetic Profiling of Methicillin-resistant Staphylococcus aureus in An African Hospital by Multiplex-PCR

Objectives: Methicillin resistant Staphylococcus aureus (MRSA) nasal carriage often precedes infection. This work aims to genetically profile the MRSA carriage of resistant genes (mecA, blaZ and tetM) and certain virulence genes (nuc, pvl, spa and scn) obtained from human nasal cavity. Methods: Phenotypically confirmed Staphylococcus aureus were Screened for oxacillin resistance and assessed for β-lactamase production. Further confirmation of identity obtained by multiplex PCR of the 16SrRNA, mecA, tetM, pvl, nuc, spa and scn genes. DNA gel fingerprint analysis was carried out and the bands were clustered in a dendrogram. Results: The study analysed 81 Staphylococcus aureus isolates for Methicillin resistance out of which 38 (46.9%) were MRSA. The DNA extraction method was effective for all MRSA isolates evaluated. All phenotypic MRSA isolates (100%) were positive for the S. aureus specific 16SrRNA gene confirming that these isolates were S. aureus strains. The nuc gene was detected in 19/38 (50%) of the MRSA isolates, blaZ gene in 14/38 (36.8%) and tetM in 18/38 (47.4%). Conclusions: The need for improved vigilance to recognize MRSA strains cannot be overemphasized. If MRSA control is not tracked, these strains will increase exponentially. J Microbiol Infect Dis 2020; 10(3):144-153.

Prevalence and anti-microbial susceptibility pattern of methicillin resistant Staphylococcus aureus at a tertiary care hospital

Background: To study about the prevalence and anti-microbial susceptibility pattern of methicillin resistant Staphylococcus aureus (MRSA).Methods: Totally 110 non-repetitive Staphylococcus aureus isolates were enrolled in this study. Isolates from different clinical specimens like pus and blood obtained from patients in tertiary care hospital and Staphylococcus aureus was identified by conventional phenotypic methods. Complete antibiotic susceptibility testing of all MRSA isolates was determined by Kirby-Bauer disc diffusion method.Results: Out of 110 isolates of S. aureus 60 were found to be methicillin-resistant Staphylococcus aureus (MRSA). The prevalence of MRSA was 54%. Out of 60 isolates, male patients 37 (63%) and female patients are 22 (37%). Maximum numbers of isolates 25 (41.6%) were from the age group of 51 to 60 years. Among these 60 isolates, all of them were found to be resistant to penicillin and oxacillin. In contrast, 98% of the isolates were found to be sensitive to linezolid. The sensitivity to chloramphenicol 70%, co-trimoxazole 60%, amikacin 58%, clindamycin 43%, ciprofloxacin 38%, erythromycin 25%.Conclusions: The observed prevalence rate was 54%. Linezolid showed the best therapeutic outcome against MRSA. Active screening plays an important role in control of MRSA.