Could bacteriophages isolated from the sewage be the solution to methicillin-resistant Staphylococcus aureus?

INTRODUCTIONS: The emergence of multidrug-resistant bacteria such as Methicillin-Resistant Staphylococcus aureus (MRSA) complicates the treatment of the simplest infection. Although glycopeptides such as vancomycin still proves to be effective in treating MRSA infections, the emergence of vancomycin-resistant strains limits the long term use of this antibiotic. Bacteriophages are ubiquitous bacterial viruses which is capable of infecting and killing bacteria including its antibiotic-resistant strains. Bactericidal bacteriophages use mechanisms that is distinct from antibiotics and is not affected by the antibioticresistant phenotypes. OBJECTIVES: The study was undertaken to evaluate the possibility to isolate bacteriolytic bacteriophages against S.aureus from raw sewage water and examine their efficacy as antimicrobial agents in vitro. METHODS: Bacteriophages were isolated from the raw sewage using the agar overlay method. Isolated bacteriophages were plaque purified to obtain homogenous bacteriophage isolates. The host range of the bacteriophages was determined using the spot test assay against the 25 MRSA and 36 MSSA isolates obtained from the Sarawak General Hospital. Staphylococcus saprophyticus, Staphylococcus sciuri and Staphylococcus xylosus were included as non-SA controls. The identity of the bacteriophages was identified via Transmission Electron Microscopy and genomic size analysis. Their stability at different pH and temperature were elucidated. RESULTS: A total of 10 lytic bacteriophages infecting S.aureus were isolated and two of them namely ΦNUSA-1 and ΦNUSA-10 from the family of Myoviridae and Siphoviridae respectively exhibited exceptionally broad host range against >80% of MRSA and MSSA tested. Both bacteriophages were specific to S.aureus and stable at both physiologic pH and temperature. CONCLUSION: This study demonstrated the abundance of S.aureus specific bacteriophages in raw sewage. Their high virulence against both MSSA and MRSA is an excellent antimicrobial characteristic which can be exploited for bacteriophage therapy against MRSA.

Effects of naringenin on vascular changes in prolonged hyperglycaemia in fructose-STZ diabetic rat model.

Chronic uncontrolled hyperglycaemia leads to increased oxidative stress and lipid peroxidation resulting in vascular complications and accelerates the progression of diabetic atherosclerosis. Though varieties of modern drugs used in the treatment of diabetes, the complications of diabetes are increasing. Naringenin (NG), has been reported to have potent antioxidant and anti-atherosclerotic properties. However, the effects of NG as vasculoprotective agent in prolonged hyperglycaemia are not well documented. Thus, this study was aimed to determine the effect of NG against vascular changes after prolonged hyperglycaemia in a diabetic rat model. Thirty adult male Sprague-Dawley rats were induced with fructose and streptozotocin to develop the diabetic rat model. After 4 weeks, the rats were randomly divided into 5 groups each group consisting of 6 animals: control, control treated with NG, non-treated diabetes mellitus (DM), DM treated with NG and metformin-treated DM. The treatment with NG (50 mg/kg) and metformin were continued for 5 weeks. The results showed that consumption of NG at 4 weeks post diabetic did not improved blood sugar, blood pressure and serum lipid profile. However, NG did significantly improve oxidative stress parameters in the aortic tissue like malondialdehyde (MDA). Analysis through light microscopy and transmission electron microscope (TEM) reverted the histological changes caused by prolonged hyperglycaemia. The findings thus demonstrated that introduction of NG after prolonged exposure to hyperglycaemia improved the vascular deterioration in diabetic group by decreasing oxidative stress evident by the reduced in the lipid peroxidation activity. Thus, this study showed the potential use of NG as adjunct in managing the diabetic condition during late presentation.

Mesosomes are a definite event in antibiotic-treated Staphylococcus aureus ATCC 25923.

Mesosomes of Staphylococcus aureus ATCC 25923 treated with antibiotics were examined morphologically under the electron microscope. The Transmission Electron Microscope Rapid Method was used to eliminate the artifacts due to sample processing. Mesosomes were seen in all the antibiotic treated bacteria and not in the control group. The main factor that contributes to the formation of mesosomes in the bacteria was the mode of action of the antibiotics. The continuous cytoplasmic membrane with infolding (mesosomes) as in the S. aureus ATCC 25923 is therefore confirmed as a definite pattern of membrane organization in gram positive bacteria assaulted by amikacin, gentamicin, ciprofloxacin, vancomycin and oxacillin antibiotics. Our preliminary results show oxacillin and vancomycin treated bacteria seemed to have deeper and more mesosomes than those treated with amikacin, gentamicin and ciprofloxacin. Further research is needed to ascertain whether the deep invagination and the number of mesosomes formed is associated with the types of antibiotic used.

Preliminary evaluation of STRIDE programme in primary schools of Malaysia.

The Students' Resilience and Interpersonal Skills Development Education (STRIDE) is a preventive drug education programme. The rational of this programme is that preventive drug education has to begin early in age, before the development of social attitudes and behaviour of students. A pre and a post intervention surveys were performed to evaluate the impact of this programme. Nine schools from three states were identified to participate in the intervention. These schools were selected based on their locations in high-drug-use areas (where the prevalence of drug use exceeds 0.5% of the student population). The new intervention curriculum was put into practice for three months in the nine schools. The overall scores obtained by each respondent to assess their knowledge on drugs and its implications were analysed. The results showed that the programme made a positive impact from the pre to post intervention programme by using the Wilcoxon Signed Rank Test (p < 0.05). A high percentage of the questions showed significant evidence through the McNemar matched pair Chi-Squared test with Bonferonni correction that there were positive shifts in the answers by comparing the pre and post intervention results (p < 0.05). Recommendations have been discussed with the Ministry of Education to integrate this programme into the national primary school curriculum.

A transmission electron microscopy study on effects of a modified Glutaraldehyde fixation on Acanthamoeba castellanii.

Transmission electron microscopy (TEM) can provide high resolution imaging of biological specimens. The study is to establish the effects of a modified glutaraldehyde (GA) compare to the standard GA fixation on Acanthamoeba castellanii from TEM perspectives and thus provide precise and accurate information on the ultrastructure studies of the parasite. By increasing the contrast, the ultrastructures of the parasite were more evident. The TEM images were obtained from parasites fixed with the modified GA and the standard GA and then the area of the nucleus and the gray values of the image of the nucleus of the parasites were measured. The mean areas of the nucleus were found to be significantly reduced in the standard GA fixed parasites (12210.4 nm2) compared to the modified GA fixed parasites (8676.3 nm2) (p < 0.05). The mean gray values of the image were significantly reduced from 2024 in the standard GA fixed parasites (2024) to the modified GA fixed parasites (1636) (p < 0.05). The study shows that the modified GA produced significantly better contrast on TEM images of the A. castellanii compared to the standard GA. This was because the modified GA generated more free water molecules during fixation and the uptake of modified GA by the nucleus of the parasite organizing all protein constituents in the cell into a more closely packed configuration than that of the standard GA. With such properties, the modified GA is a better fixative providing better images for ultrastructures of the parasite.