title: Microbial colonization of irradiated pathogenic yeast to catheter surfaces: Relationship between adherence, cell surface hydrophobicity, biofilm formation and antifungal susceptibility. A scanning electron microscope analysis.
abstract: OBJECTIVE
  Technological advances such as long-term indwelling catheters have created milieu in which infections are a major complication. Thus it is essential to be able to recognize, diagnose, and treat infections occurring in immunocompromised patients.
  
  
  METHODS
  Adherence assay and quantitation of biofilms was performed by a spectrophotometric method, hydrophobicity was evaluated by adhesion to p-xylene. The minimum inhibitory concentration (MIC) of Nystatin was carried out by a well dilution method.
  
  
  RESULTS
  Out of 100 bladder cancer patients, 23 pathogenic yeast isolates were identified. The samples were taken from urinary catheters and urine collected from their attached drainage bags. Pathogenic yeast identified were species of Candida, Cryptococcus, Saccharomyces, Blastoschizomyces, Trichosporn, Hansenula, Prototheca and Rhodotorula. With the exception of Rhodotorula minuta, the yeast were sensitive to the antimycotic agent (Nystatin) used before and after in vitro gamma irradiation at 24.41 Gy as measured by a disc diffusion method. All tested yeast strains were slime producers and showed positive adherence reactions. There were considerable differences in adherence measurements after irradiation. An increase in adherence measurement values (using a spectrophotometric method) after irradiation were detected in four strains whereas eight other strains showed a reduction in their adherence reaction. The cell surface hydrophobicity (CSH) was evaluated by adhesion to p-xylene. Candida tropicalis showed a hydrophobic reaction with an increase in the cell surface hydrophobicity after irradiation. Scanning electron microscopy of irradiated C. tropicalis showed marked abnormalities in cell shape and size with significant reduction in adherence ability at the MIC level of Nystatin (4 μg/ml).
  
  
  CONCLUSIONS
  More basic research at the level of pathogenesis and catheter substance is needed to design novel strategies to prevent fungal adherence and to inhibit biofilm formation.
authors.affiliation: Drug Radiation Research Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority , Nasr City, Cairo.
authors.forename: Hala Abdallah
authors.initials: HA
authors.lastname: Farrag
authors.forename: Alzahraa
authors.initials: A
authors.lastname: A-Karam El-Din
authors.forename: Zeinab Galal
authors.initials: ZG
authors.lastname: Mohamed El-Sayed
authors.forename: Soheir
authors.initials: S
authors.lastname: Abdel-Latifissa
authors.forename: Mona Mohamed
authors.initials: MM
authors.lastname: Kamal
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects*; D055499:Catheter-Related Infections / Q000188:drug therapy / Q000209:etiology / Q000382:microbiology; D002448:Cell Adhesion / Q000528:radiation effects; D002462:Cell Membrane / Q000528:radiation effects; D025141:Drug Resistance, Fungal; D005720:Gamma Rays; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008855:Microscopy, Electron, Scanning; D009761:Nystatin / Q000494:pharmacology; D001749:Urinary Bladder Neoplasms / Q000382:microbiology; D062885:Urinary Catheters / Q000009:adverse effects / Q000382:microbiology; D014774:Virulence; D015003:Yeasts / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*
chemical_list: D000935:Antifungal Agents; D009761:Nystatin
keywords: Yeast; antimycotic; colonization; radiotherapy; scanning electron microscope; urinary catheters