Prospective study of the microbiological flora of hearing aid moulds and the efficacy of current cleaning techniques.
BACKGROUND
Wearing hearing aid earmoulds has been implicated as a predisposing factor in the development of chronic otitis externa. Audiologists come into contact with a large number of hearing aid earmoulds and these could potentially harbour pathogenic micro-organisms, with the risk of subsequent cross infection. Cleaning with dilute alcohol is widely used in an attempt to break the chain of infection.


OBJECTIVE
To determine the presence and nature of microbial flora on hearing aid earmoulds and the efficacy of cleaning methods used to prevent cross infection.


METHODS
Secondary health care within the audiology department of Addenbrooke's Hospital, Cambridge, UK.


METHODS
A prospective, observational study.


METHODS
Hearing aid earmoulds were swabbed before and after cleaning. Samples were cultured to determine qualitatively and quantitatively the microbiological flora present before and after cleaning.


RESULTS
Twenty out of 21 (95 per cent) earmoulds had microbes present and, of these, 19/20 (95 per cent) had a polymicrobial profile. Coagulase negative staphylococci and diphtheroids were the most frequent microbial isolates, but pathogenic bacteria and fungi were also demonstrated on earmoulds both before and after cleaning.


CONCLUSIONS
The polymicrobial flora, including recognized pathogens, that colonizes earmoulds may lead to chronic otitis externa. Cleaning with 70 per cent alcohol solution was ineffective, in particular for pathogenic fungi on earmoulds.
Ahmad
N
N
Department of Otorhinolaryngology-Head & Neck Surgery, Cambridge University Hospitals NHS Foundation Trust, Addenbrooke's Hospital, Cambridge, UK.
Etheridge
C
C
Farrington
M
M
Baguley
D M
DM
D000368:Aged; D000369:Aged, 80 and over; D002175:Candida / Q000302:isolation & purification; D002908:Chronic Disease; D004866:Equipment Contamination; D005260:Female; D006310:Hearing Aids / Q000009:adverse effects / Q000382:microbiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010032:Otitis Externa / Q000517:prevention & control*; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013242:Sterilization / Q000379:methods / Q000592:standards*