Chelating effects of siderophore in reducing organ dysfunction caused by iron overload in ICR Mice

Background and Objectives@#Iron is an essential element that plays a vital role in a wide variety of cellular processes. But when present in excess concentration in organs, it may increase the risk for liver disease, heart failure, and diabetes. Recently, siderophores, which are iron-chelating agents produced by microorganisms, have attracted tremendous attention because of their strong binding and high selectivity to the ferric form of iron. Thus, the use of siderophore in sequestering excess iron in the body as a form of therapy is very attractive. This study determined the effects of commercially available siderophore in sequestering excess iron in organs such as liver, heart, and pancreas under excess iron conditions. @*Methodology@#First, iron-overload was induced by injecting iron dextran (20 mg) into male ICR mice for three consecutive days. The effects of iron to the liver, heart, and pancreas and the possible sequestration by siderophore were determined by scoring histological sections. The liver iron concentration was also assessed by atomic absorption spectroscopy (AAS).@*Results and Conclusion@#The study showed that iron-overloaded mice exhibited skin hyperpigmentation and hemosiderosis in liver, heart, and pancreas. Significant changes in the liver include hepatomegaly and development of tumor. Iron-overloaded mice had 2,935% increase in liver iron content compared to the salinetreated mice. However, when iron-overloaded mice were treated with either 100 µg or 200 µg siderophore, there was a 77% and 84% decrease in liver iron content, respectively. Moreover, the treatment of ironoverloaded mice with siderophore prevented the development of hemosiderosis, tumor, and structural changes in the tissues studied. The results showed that siderophore can effectively reduce excess iron and organ damage in iron-overloaded mice and can be potentially employed in chelation therapy of iron-overload diseases. Further studies on the possible mechanisms of siderophore aside from decreasing iron excess and lowering organ dysfunction are recommended.

Screening of bacteriophages against different genotypes of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae Isolated from five hospitals in Cavite and Metro Manila, Philippines

Background@#Extended-spectrum β-lactamase (ESBL) K. pneumoniae infections are emerging health problems in the Philippines. Recently, bacteriophages have been explored to target several antibiotic-resistant bacteria as a potential alternative therapeutic option to conventional antibiotics. @*Objectives@#This study isolated extended-spectrum β-lactamase (ESBL) producing K. pneumoniae harboring different β-lactamase genes to evaluate the host range specificity of isolated bacteriophages.@*Methodology@#K. pneumoniae were isolated from five selected hospitals in Cavite and Metro Manila, Philippines and their ESBL-production was determined through the Phenotypic Confirmatory Disc Diffusion Test (PCDDT). The identity of the isolates was then confirmed by amplification and sequencing of the 16 rRNA gene. The type of β-lactamase genes carried by the K. pneumoniae ESBL-positive strains was detected by amplification of the bla , bla , bla and bla genes. Meanwhile, bacteriophages were isolated from CTX-M TEM SHV OXA-1 water samples in Marikina River and their host range specificity was tested against the different ESBLproducing K. pneumoniae strains.@*Results@#From a total of 25 K. pneumoniae, 6 (24%) were found to be ESBL-producers by PCDDT. Genotyping of the β-lactamase genes showed that one of the phenotypically confirmed isolates contained the bla while CTX-M another possessed both the bla and bla genes. Furthermore, another isolate harbored the bla , bla , CTXM SHV CTX-M OXA-1 and bla genes while the remaining isolates contained all the four bla genes tested. Meanwhile, two virulent SHV phages namely, KP1 and KP2 that showed the largest clearing zones against K. pneumoniae were selected to determine their host range specificity against the different ESBL-positive K. pneumoniae strains. Both phages were able to infect and lyse all ESBL-positive K. pneumoniae regardless of the type or number of bla genes they possessed. Phage KP2, which showed the highest lytic capability, was then subjected to Transmission Electron Microscopy (TEM) and was found to belong to the Order Caudovirales under the Family Myoviridae. @*Conclusion@#This study showed that phage KP2 was host-specific to the different ESBL-producing K. pneumoniae harboring single or multiple bla genes suggesting that it might hold a great potential for possible phage therapy against ESBL-producing K. pneumoniae infections.