title: Quantity of aerobic bacteria in the bony portion of the external auditory canal of children.
abstract: OBJECTIVE
  the human external auditory canal (EAC) hosts a commensal bacterial flora of mainly non-pathogens, but bacterial pathogens may also be present. The latter are important in the aetiopathogenesis of external otitis and middle ear cholesteatoma with discharge. The purpose of this study was to quantify the bacteria normally harboured in the healthy EAC and on a well-defined region of the cavum conchae (CC) of children.
  
  
  METHODS
  bacterial samples were collected from the CC and bony portion of the EAC of 32 children (18 boys, 14 girls; median age 5 years). Prior to sampling, the EACs were either left untreated, anaesthetized with Bonain's solution, or washed with 70% alcoholic solution. The samples were incubated at 37 degrees C and evaluated regarding bacterial species and number.
  
  
  RESULTS
  the predominant bacterial non-pathogens were coagulase-negative Staphylococci and coryneforms (diphtheroids) and pathogens Staphylococcus aureus and Pseudomonas aeruginosa. Total bacterial counts of the CC ranged between 2 x 10(3) and 4.6 x 10(4) CFU/cm(2) (median value 7 x 10(3); n = 14). Total bacterial counts from the bony portion of the EAC ranged between 0 and 5.7 x 10(7) CFU/EAC (median value 8 x 10(3); n = 32). Pre-treatment of the EACs with Bonain's solution containing the highly bactericidal substance phenol or with 70% alcoholic solution did not sterilize the EAC.
  
  
  CONCLUSIONS
  small numbers of bacterial non-pathogens (and sometimes pathogens) are found in the EAC of children. Neither phenol nor 70% alcoholic solution can inhibit or eradicate all these microorganisms.
authors.affiliation: Department of Otolaryngology, Institute of Clinical Medicine, University of Tromsø, N-9037 Tromsø, Norway. larseric@fagmed.iut.no
authors.forename: Lars-Eric
authors.initials: LE
authors.lastname: Stenfors
authors.forename: Simo
authors.initials: S
authors.lastname: Räisänen
mesh_terms: D002648:Child; D002675:Child, Preschool; D018424:Cholesteatoma, Middle Ear / Q000188:drug therapy / Q000382:microbiology; D046508:Culture Techniques; D004431:Ear, External / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D010032:Otitis Externa / Q000188:drug therapy / Q000382:microbiology*; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification*