Polyhexamethylene Biguanide and Nadifloxacin Self-Assembled Nanoparticles: Antimicrobial Effects against Intracellular Methicillin-Resistant Staphylococcus aureus

The treatment of skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge, partly due to localization of the bacteria inside the host’s cells, where antimicrobial penetration and efficacy is limited. We formulated the cationic polymer polyhexamethylene biguanide (PHMB) with the topical antibiotic nadifloxacin and tested the activities against intracellular MRSA in infected keratinocytes. The PHMB/nadifloxacin nanoparticles displayed a size of 291.3 ± 89.6 nm, polydispersity index of 0.35 ± 0.04, zeta potential of +20.2 ± 4.8 mV, and drug encapsulation efficiency of 58.25 ± 3.4%. The nanoparticles killed intracellular MRSA, and relative to free polymer or drugs used separately or together, the nanoparticles displayed reduced toxicity and improved host cell recovery. Together, these findings show that PHMB/nadifloxacin nanoparticles are effective against intracellular bacteria and could be further developed for the treatment of skin and soft tissue infections

Bactericidal and Anti-biofilm Effects of Polyhexamethylene Biguanide in Models of Intracellular and Biofilm of Staphylococcus aureus Isolated from Bovine Mastitis

Staphylococcus aureus infection is a common cause of mastitis, reducing milk yield, affecting animal welfare and causing huge economic losses within the dairy industry. In addition to the problem of acquired drug resistance, bacterial invasion into udder cells and the formation of surface biofilms are believed to reduce antibiotic efficacy, leading to treatment failure. Here, we investigated the antimicrobial activities of enrofloxacin, an antibiotic that is commonly used in mastitis therapy and polyhexamethylene biguanide (PHMB), an antimicrobial polymer. The antimicrobial activities were tested against intracellular S. aureus in infected Mac-T cells (host cells). Also, fluorescein-tagged PHMB was used to study PHMB uptake and localization with S. aureus within the infected Mac-T cells. Anti-biofilm activities were tested by treating S. aureus biofilms and measuring effects on biofilm mass in vitro. Enrofloxacin and PHMB at 15 mg/L killed between 42 to 92 and 99.9% of intracellular S. aureus, respectively. PHMB-FITC entered and colocalized with the intracellular S. aureus, suggesting direct interaction of the drug with the bacteria inside the host cells. Enrofloxacin and PHMB at 15 mg/L reduced between 10 to 27% and 28 to 37% of biofilms’ mass, respectively. The half-maximal inhibitory concentrations (IC50) obtained from a cytotoxicity assay were 345 ± 91 and 21 ± 2 mg/L for enrofloxacin and PHMB, respectively; therefore, both compounds were tolerated by the host cells at high concentrations. These findings suggest that both antimicrobials are effective against intracellular S. aureus and can disrupt biofilm structures, with PHMB being more potent against intracellular S. aureus, highlighting the potential application of PHMB in mastitis therapy

The impact of IEQ on occupants’ satisfaction in Malaysian buildings

This paper focuses on the importance of occupant satisfaction with indoor environmental quality in buildings as well as the effect of indoor environmental quality towards occupants’ satisfaction. This research applied post-occupancy evaluation as a method to indicate the building occupants’ needs, their satisfaction and comfort level. The research is based on a case study approach whereby a questionnaire survey was conducted among 25 organizations involved in managing office buildings. A total of 115 questionnaires were returned for evaluation of occupants’ overall satisfaction from aspects of indoor environmental quality in these buildings and to determine the occupants’ satisfaction level within these buildings. The findings revealed that indoor environment factors that could contribute to occupants’ satisfaction consists of lighting, air quality and aesthetic perception. These classifications were made based on the factor analysis done with 22 attributes of the indoor environment. The majority of occupants are satisfied with their health conditions and do not face any serious health problems. However, occupants highlighted that some environmental conditions, health effects, air movement, ventilation and air freshness are important criteria for their satisfaction and comfort. This study provides insights into how occupants perceive their indoor environment and comfort, and identify problems that could arise in buildings

HEAVY METALS IN TUNA SPECIES MEAT AND POTENTIAL CONSUMER HEALTH RISK : A REVIEW

Marine fishes are one of the protein sources and they form a significant part of human diet around the world. In particular, tuna fisheries are considered as the largest and most specialized commercially important group of species among all commercial fishes. The preparing tuna methods such as cooking and canning might alter the level of heavy metals inside the meat. The heat that applied to the meat might be decreased the moisture content in tuna meat, thus give some effects to the heavy metal level. Other than that, the different composition and function of different parts of tuna can contribute to the various level of heavy metals analysed. The metal contamination in tuna species meat has put serious question to the safety level of fish intake to the community. It represent an abiding threat to human health as it has been linked to some adverse health effects such as mental retardation, kidney damage, and various types of cancer and even worse, death could occur.The following review articles presents the findings of the work carried out by the various researchers in the past on the heavy metal pollution in samples of Tuna species around the world

Metal concentration at surface water using multivariate analysis and human health risk assessment

This study defined the concentration of metals in Kerteh and Paka River water and their potential health risk towards human. 54 water samples were collected and analyzed using ICP-OES. Results revealed that most of the stations in Kerteh River gave the higher concentration of Cd, Cu, Zn, Co, Ni, As, Cr and Pb compared to Paka River. However As, Cr and Pb have exceeded the permissible limit of Malaysia standard for all stations in both rivers. Cd, Cu, Zn, Co and Ni were below than Malaysian standard permissible levels during the sampling period. The principal component analysis (PCA) revealed that both geogenic and anthropogenic sources were responsible to possible metals contamination in both rivers. Moreover, risk assessments for all metals were within the safe limits, except for As in the Kerteh River for both adult and child as well as to Paka River for both genders

Fresh and hardened properties of concrete containing effective microorganisms

Nowadays, concrete is popularly used in many areas and applications in construction industry. If designed and manufactured properly it can be one of the most durable construction materials. However, during the life span of the structure the surrounding environment where the structure is built may pose long-term durability problem to concrete such as cracks and corrosion of steel reinforcement. Thus, researchers around the world continue searching for any possible means to improve concrete qualities. This paper presents study on the effects of Effective Microorganism on fresh and hardened properties of concrete. The percentage of Effective Microorganisms (EM) used in this study was 10% and incorporated in the concrete mix by replacing the water content. In this research work, a number of control and EM concrete cube samples were cast, cured in water and tested at the ages of 3, 7 and 28 days. The workability of fresh concrete was measured through the slump test. The effect of EM on hardened concrete was assessed through compression test and ultrasonic pulse velocity (UPV) test. The experimental result shows that the workability of concrete with EM was 67% higher than the control concrete. This may indicate that the EM has the potential to be used as workability enhancer. In terms of compressive strength, the EM concrete recorded 8% higher strength at 28 days compared to concrete without EM. In addition, the early strength of EM concrete was found to be higher by 41% and 27% at 3 and 7 days compared to control, respectively. The UPV result for EM concrete also shows higher value than control concrete indicating denser concrete. All experimental results indicated that the use of EM has positive effects on concrete properties

Frailty in primary care: a review of its conceptualization and implications for practice

Frail, older patients pose a challenge to the primary care physician who may often feel overwhelmed by their complex presentation and tenuous health status. At the same time, family physicians are ideally suited to incorporate the concept of frailty into their practice. They have the propensity and skill set that lends itself to patient-centred care, taking into account the individual subtleties of the patient's health within their social context. Tools to identify frailty in the primary care setting are still in the preliminary stages of development. Even so, some practical measures can be taken to recognize frailty in clinical practice and begin to address how its recognition may impact clinical care. This review seeks to address how frailty is recognised and managed, especially in the realm of primary care