title: Surface topological differences of phage infected uropathogenicEscherichia coli(UPEC) strains, revealed by atomic force microscopy.
abstract: BACKGROUND
  Atomic force microscopy (AFM) is an advance microscopic technique that provides three dimensional structures of cell surfaces with high resolution. In the present study AFM was used for comparative analysis of surface topology of phage infected and uninfected UropathogenicEscherichia coli(UPEC) cells. Two UPEC strains NE and HN were isolated from urine samples of Urinary tract infection patients and their specific narrow host range lytic phages 3S and HNΦ were isolated from the sewage of different areas.
  
  
  RESULTS
  On the basis of one step growth curve both phages characterized as short latent period phages with latency period of about 30 min. On AFM analysis significant difference in topology of healthy and infected cells were observed. It was hypothesized that progeny of both lytic phages released out from their respective host cells in different manner. The image of 3S infected UPEC host cells (NE) revealed multiple internal projections which showed progeny phages released out from host cells through these multiple sites. Whereas images of HNΦ infected HN host cells showed central depression which illustrated that new phages released out through single exit point from the middle of cell.
  
  
  CONCLUSIONS
  These results are significant to extend future studies on isolated phages as an effective tool for phage therapy.
authors.affiliation: Department of Microbiology, University of Karachi, Karachi, Pakistan.
authors.forename: Bassamah
authors.initials: B
authors.lastname: Hanif
authors.affiliation: Department of Microbiology, University of Karachi, Karachi, Pakistan.
authors.forename: Nusrat
authors.initials: N
authors.lastname: Jamil
authors.affiliation: International Centre for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, Pakistan.
authors.forename: Muhammad Raza
authors.initials: MR
authors.lastname: Shah
keywords: AFM; Central depression; Multiple internal projections; Short latent period; Single site; UPEC