A study was carried out to determine the pathogenicity (hemolytic activity) on corals (Turbinaria sp.) and sea bass (Lates calcarifer) of Aeromonas hydrophila from water, sediment, and coral. Samples were collected from coastal water and coral reef areas. One hundred and sixty-two isolates were successfully isolated. Out of 162, 95 were from seawater, 49 from sediment, and 18 from coral. Sixteen isolates were picked and identified. Isolates were identified using a conventional biochemical test, the API 20NE kit, and 16S rRNA nucleotide sequences. Hemolytic activity was determined. Out of 16 isolates, 14 isolates were β-hemolytic and two isolates were non-hemolytic. Corals infected with A. hydrophila suffered bleaching. Similar effect was observed for both hemolytic and non-hemolytic isolates. Intramuscular injection of A. hydrophila into sea bass resulted in muscular bleeding and death. Higher infection rates were obtained from hemolytic compared to non-hemolytic strains of A. hydrophila isolates.

We report the first study on the occurrence of high-level aminoglycoside-resistant (HLAR) Enterococci in coastal bathing waters and beach sand in Malaysia. None of the encountered isolates were resistant to high levels of gentamicin (500 μg/mL). However, high-level resistance to kanamycin (2,000 μg/mL) was observed in 14.2 % of tested isolates, the highest proportions observed being among beach sand isolates. High-level resistance to kanamycin was higher among Enterococcus faecalis and Enterococcus faecium than Enterococcus spp. Chi-square analysis showed no significant association between responses to tested antibiotics and the species allocation or source of isolation of all tested Enterococci. The species classification of encountered Enterococci resistance to vancomycin was highest among Enterococcus spp. (5.89 %) followed by E. faecium (4.785) and least among E. faecalis. A total of 160 isolates were also tested for virulence characteristics. On the whole, caseinase production was profoundly highest (15.01 %) while the least prevalent virulence characteristic observed among tested beach Enterococci was haemolysis of rabbit blood (3.65 %). A strong association was observed between the source of isolation and responses for each of caseinase (C = 0.47, V = 0.53) and slime (C = 0.50, V = 0.58) assays. Analysis of obtained spearman's coefficient showed a strong correlation between caseinase and each of the slime production (p = 0.04), gelatinase (p = 0.0035) and haemolytic activity on horse blood (p = 0.004), respectively. Suggestively, these are the main virulent characteristics of the studied beach Enterococci. Our findings suggest that recreational beaches may contribute to the dissemination of Enterococci with HLAR and virulence characteristics.

Bacteriocin-producing Pseudomonas putida strain FStm2 isolated from shark showed broad range of antibacterial activity against all pathogens tested except Bacillus subtilis ATCC11774, MRSA N32064, Proteus mirabilis ATCC12453, Enterococcus faecalis ATCC14506, Salmonella typhimurium ATCC51312, Salmonella mutan ATCC25175, and Aeromonas hydrophila Wbf314. Of the three growth media tested in this study, TSB was observed to support the bacteriocin activity the most. While the highest bacteriocin activity was observed for media supplemented with 1 % NaCl, there was an observed reduction in bacteriocin activity with increasing salt concentration. Although the least bacteriocin activity was observed for marine broth, addition of increasing amounts of tryptone, glucose, or yeast extract increased bacteriocin activity. This was, however, contrary to the effect observed when MgSO4 and MnSO4 were added as supplements. In the presence of α-amylase, lipase, DNase, and RNase, a positive effect on bacteriocin production was observed. Proteinase K strongly inhibited bacteriocin production. Furthermore, the bacteriocins produced were heat stable within the temperature range of 30-70 °C. Bacteriocin activity also was not affected within a wide pH range of 3-9. Exposure to detergents did not inhibit the activity of the bacteriocin at the concentrations tested. Instead, a positive effect on the relative activity of produced bacteriocin was observed as sodium dodecyl sulfate (SDS), EDTA, and Tween 20 at 1 % concentration all improved bacteriocin activity when the cell-free supernatant was tested against Serratia marcescens ATCC 13880. The bacteriocin was purified by ammonium sulfate precipitation and gel filtration on a Superdex-200 column. SDS-PAGE analysis of the partially purified bacteriocin revealed an apparent molecular weight of ~32 kDa.

Aims:The aim of the present study is to investigate the effect of bacteriocin from Pseudomonas putida FStm2 on biofilm-forming bacteria isolated from urinary catheter. Methodology and results:In this study, 25 bacteria isolates were successfully isolated from urinary catheter. Sixteen of the isolates were urease positive. Results of crystal violet test showed that 8 isolates were active biofilm formers in microtiter plate. Seven isolates were active biofilm formers in urinary catheter filled with nutrient broth (NB) and 9 isolates formed biofilm in catheters filled with artificial urine. Bacteriocin-producing Pseudomonas putida strain FStm2 was isolated from shark skin. The antibacterial spectrum of the bacteriocin was determined using the well diffusion method and activity was evident against three Burkholderia cepacia isolates and one Staphylococcus hominis isolate from urinary catheter. Conclusion, significance and impact study: Bacteriocin from P. putida FStm2 has good antimicrobial activity against B. cepacia and S. hominis. It can be a good candidate as anti-biofilm in combating urinary catheter infection. Further studies such as the mechanism of action of the bacteriocin against both bacterial species should be studied in detail if it is to be developed as a bacteriocide.