Biofilm formation byAcinetobacter baumanniistrains isolated from urinary tract infection and urinary catheters

Abstract

Fifty Acinetobacter isolates were obtained from urinary tract infections and urinary catheter samples. Analytical profile index assays identified 47 isolates as Acinetobacter baumannii and three as Acinetobacter lwoffii. Six A. baumannii isolates (A1-A6) displayed hydrophobicity indices >70%. Twenty isolates exhibited lectin activity. Biofilm formation by these isolates was compared with those with low hydrophobicity index values (A45-A50). Biofilms on different surfaces were confirmed by light microscopy, epifluorescence microscopy and by obtaining scanning electron microscope images. Biofilm production was maximal at 30 °C, pH 7.0 in a medium with 5.0 g L(-1) NaCl, and its efficiency was reduced on urinary catheter surfaces at sub-minimum inhibitory concentration concentrations of colistin. Plasmid-mediated antibiotic resistance was observed in selected isolates of A. baumannii and experiments of conjugation and transformation showed the occurrence of gene transfer. Plasmid curing was used to examine the function of plasmids. Five plasmids of A. baumannii A3 were cured but no differences were observed between wild-type and plasmid-cured strains with respect to the biofilm formation capabilities. The prevalence of A. baumannii strains with biofilm mode of growth could explain their ability to persist in clinical environments and their role in device-related infections.

Synthesis of silver nanoparticles using Dioscorea bulbifera tuber extract and evaluation of its synergistic potential in combination with antimicrobial agents

“…A very interesting observation that A. baumannii, a nosocomial pathogen resistant to almost all known antibiotics and metal salts commonly used in medicine, could also be sensitized in the presence of silver nanoparticles. [64][65][66][67] Therefore, this combinational approach of antibiotics and silver nanoparticles would provide a strategy for effective control of A. baumannii. From the results, we can conclude that the antimicrobial effect of silver nanoparticles is the key contributor to the synergistic effect observed with a combination of silver nanoparticles and antibiotics.…”

Relationship between ultrasound bone parameters, lung function, and body mass index in healthy student population

“…The glass used in this study is probably the least suitable substrate for biofilm formation; it is hydrophilic, inert, and negatively charged, all of the properties that disfavour biofilm formation. For illustration, hospital isolates of A. baumannii produced significantly more biofilm on polycarbonate and polypropylene than on glass (26).…”

Hyperosmotic Agents and Antibiotics Affect Dissolved Oxygen and pH Concentration Gradients in Staphylococcus aureus Biofilms

“…Staphylococcus aureus, a common human pathogen, is often associated with biofilm infections (7)(8)(9) in chronic wounds (8,10,11). Such infections are problematic to treat because of the slow penetration of antimicrobials and antibiotics through the biofilm matrix (10,(12)(13)(14) and the formation of persister cells (15). In vitro experiments have demonstrated that the bacterial gene regulation and resistance to antibiotics inside a biofilm differ from cell responses in planktonic culture (2,5,(16)(17)(18).…”