Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 6 Articles
S. aureus represents a public health challenge worldwide on the basis of their resistance to antimicrobials as well as the production of certain virulence factors such as enterotoxins. Detection of enterotoxin production, plasmid profiles and antimicrobial susceptibility testing were carried out. Four out of 10 S. aureus isolates produced different types of enterotoxins. Plasmid profile revealed the presence of 3 plasmids (42, 4 and 2 MDa) in 2 out of 4 enterotoxigenic S. aureus isolates and none in the remaining 2 isolates. Also, enterotoxigenic S. aureus isolates exhibited multiple drug resistance. Conjugation experiment revealed the transfer of 42 MDa plasmid to S. aureus and Enteococcus faecalis recipient strains. These transconjugants were able to produce enterotoxin D and conferred resistance to chloramphenicol (CH) and sulfamethoxazole (SSS). A positive direct and significant correlation was found between enterotoxin D transfer and the co-transfer of CHL and SSS....
A total of 4 Shigella flexneri isolates showed positive sereny test indicating the capability of invasiveness. This was also confirmed by testing the adhesion and invasion to HeLa cells in-vitro. At the molecular level, inv gene was amplified and detected in the four test isolates at 320 bp. Susceptibility testing revealed multiple drug resistance in all of the isolates with two resistance patterns. Electrophoregram showed a common plasmid with 140 MDa in the plasmid profile of all isolates. Following conjugation and curing experiments, the transconjugant tSh173 gained all plasmids and became invasive to HeLa cells. Elimination of that plasmid by curing was accompanied by the loss of this virulence factor. Moreover, loss of 140 MDa plasmid was associated with the loss of ampicillin, cephradine, norfloxacin, enoxacin and chloramphenicol resistance markers. A positive direct and significant correlation was found between invasiveness transfer and the co-transfer of the above resistance markers. Thus, it appears that inv gene which mediates the invasiveness of the bacteria into the host cells is plasmid encoded and can be transferred by conjugation and expressed by the transconjugants....
Objectives. Slowly growing mycobacteria (SGM) are prevalent worldwide and cause an extensive spectrum of diseases. Methods.\nIn this study, the antimicrobial susceptibility of 33 reference strains of SGM to 19 antimicrobial agents was tested using a modified\nmicrodilutionmethod. Results. Cefmetazole (32/33) and azithromycin (32/33) exhibited the highest antimicrobial activity, and dapsone\n(9/33) exhibited the lowest activity against the tested strains.Cefoxitin (30/33), cefoperazone (28/33), and cefepime (28/33)were\neffective against a high proportion of strains, and macrolides were also highly effective as well as offering the benefit of convenient\noral administration to patients. Linezolid (27/33), meropenem (26/33), sulfamethoxazole (26/33), and tigecycline (25/33) showed\nthe highest activity; clofazimine (20/33) and doxycycline (18/33) showed intermediate activity; and rifapentine (13/33), rifabutin\n(13/33), and minocycline (11/33) showed low antimicrobial activity, closely followed by thioacetazone (10/33) and pasiniazid\n(10/33), against the tested organisms. According to their susceptibility profiles, the slowly growing species Mycobacterium avium\nand Mycobacterium simiae were the least susceptible to the tested drugs, whereas Mycobacterium intracellulare, Mycobacterium\nasiaticum,Mycobacterium scrofulaceum,Mycobacterium szulgai,Mycobacterium branderi, and Mycobacterium holsaticum were the\nmost susceptible. Conclusions. In summary, cephalosporins and macrolides, particularly cefmetazole, azithromycin, clarithromycin,\nand roxithromycin, showed good antimicrobial activity against the reference strains of SGM....
Background: Genus Clostridium accompanies more than 200 known species and at least 30 among them are associated\nwith human and animal diseases. At the moment, the treatment of clostridial infections is based on use of antibiotics.\nHowever, due to the European ban on the use of antibiotics in livestock production, novel therapeutic strategies for\ntreatment of these hardly curable infections have been evaluated. Hence, in this study the antimicrobial effect of newly\ndesigned probiotic culture consisted of natural isolates Lactobacillus helveticus BGRA43, Lactobacillus fermentum BGHI14\nand Streptococcus thermophilus BGVLJ1-44 against Clostridium difficile and Clostridium perfringens was analyzed.\nResults: The probiotic culture showed strong in vitro antimicrobial effect on C. difficile (human clinical isolate).\nIn addition, individual strains and the probiotic combination exhibited immunomodulatory activity. The probiotic\ncombination significantly increased the proliferation of GALT lymphocytes. At the other hand, none of the bacterial\ntreatments (individual strains and the combination) induced the production of proinflammatory cytokines IL-6 and IL-1�²\nby intestinal epithelial cells, Caco-2. Interestingly, Caco-2 cells exposed to the probiotic combination produced\nsignificantly elevated amount of TGF�² pointing to potential protecting effect of the probiotic. In addition, the\nresults of field trial on spontaneously infected goats revealed reduction of C. perfringens in goats (below the\ndetection threshold) after the probiotic treatment.\nConclusions: The results of this study indicated that the novel probiotic deserves to be further investigated\nas a promising antimicrobial agent against C. difficile and C. perfringens....
Background: Staphylococcus aureus more than any other human pathogen is a better model for the study of the\nadaptive evolution of bacterial resistance to antibiotics, as it has demonstrated a remarkable ability in its response\nto new antibiotics. This study was designed to investigate the in vitro transfer of mecA gene from methicillin\nresistant S. aureus to methicillin susceptible S. aureus.\nResult: The recipient transconjugants were resistant to erythromycin, cefpodoxime and were mecA positive. PCR\namplification of mecA after mix culture plating on Luria Bertani agar containing 100 �¼g/mL showed that 75% of the\ndonor and 58.3% of the recipient transconjugants were mecA positive. Additionally, 61.5% of both the donor cells\nand recipient transconjugants were mecA positive, while 46.2% and 41.75% of both donor and recipient\ntransconjugants were mecA positive on LB agar containing 50 �¼g/mL and 30 �¼g/mL respectively.\nConclusion: In this study, the direction of transfer of phenotypic resistance as well as mecA was observed to have\noccurred from the donor to the recipient strains. This study affirmed the importance of horizontal transfer events in\nthe dissemination of antibiotics resistance among different strains of MRSA....
Cellulase can be derived from a variety of living organisms, ranging from micro-organisms to plants and humans. Microorganisms are the most important sources for the production of cellulase. In the present study the mangrove plant species Rhizophora mucronata were collected from Kurusadai Island, Mandapam, Rameswaram. In nutrient agar medium 18 × 102 CFU/g cells were isolated from the leaf sample of Rhizophora mucronata. A total of 10 different bacterial strains were isolated on the basis of their different colony morphology and of these only four strains showed cellulase producing activity. On CMC agar plate, four different bacterial colonies, which produced clear zones were selected and purified. Among the most potent cellulase producing bacterial strains, the strain, which showed maximum zone of clearance (24 mm) were selected for further study. The morphological, biochemical and gram staining properties indicates that this strain is Bacillus subtilis. After identifying the Bacillus subtilis and it was evaluated for cellulase enzyme production with different parameters....
Loading....