title: Effect of biofilm formation on the excretion of Salmonella enterica serovar Typhi in feces.
abstract: OBJECTIVE
  We hypothesized that Salmonella enterica serovar Typhi (S. Typhi) with higher biofilm and capsule production capability are more able to survive continuously in typhoid patients/carriers, with subsequent prolonged shedding in feces.
  
  
  METHODS
  Bacterial cell release from biofilm (produced in vitro and confirmed by specific staining and electron microscopy) and comparative cytotoxicity were studied on Caco2 cells. Functionality of the biofilm diffusion barrier was tested against ciprofloxacin. Biofilm production was graded and semi-quantified as -, +, ++, +++, and ++++.
  
  
  RESULTS
  Out of 30 isolates, 23 produced biofilm. The average post-treatment detection of S. Typhi in blood was 7-13 days and in stool was 13-32 days. A fall in cell count from 10⁴ to approximately 10¹ over the course of 3 days as compared to total elimination of planktonic cells in 16 h after ciprofloxacin application substantiated the protective role of biofilm. Lactic dehydrogenase release ranged from 38% in non-biofilm producers to 97% in the highest biofilm producers, indicating increased pathogenic behavior.
  
  
  CONCLUSIONS
  The period of S. Typhi clearance from typhoid patients after recovery was found to be directly related to biofilm production capability.
authors.affiliation: Molecular Diagnostics and Research Laboratory, Nuclear Medicine, Oncology and Radiotherapy Institute, Islamabad, Pakistan.
authors.forename: Abida
authors.initials: A
authors.lastname: Raza
authors.forename: Yasra
authors.initials: Y
authors.lastname: Sarwar
authors.forename: Aamir
authors.initials: A
authors.lastname: Ali
authors.forename: Amer
authors.initials: A
authors.lastname: Jamil
authors.forename: Asma
authors.initials: A
authors.lastname: Haque
authors.forename: Abdul
authors.initials: A
authors.lastname: Haque
mesh_terms: D000293:Adolescent; D000328:Adult; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism; D057138:Bacterial Shedding / Q000502:physiology*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D018938:Caco-2 Cells; D002648:Child; D002939:Ciprofloxacin / Q000494:pharmacology*; D005243:Feces / Q000382:microbiology; D005260:Female; D005334:Fever; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012485:Salmonella typhi / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology*; D013997:Time Factors; D014435:Typhoid Fever / Q000382:microbiology*; D014774:Virulence; D055815:Young Adult
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D002939:Ciprofloxacin; D007770:L-Lactate Dehydrogenase