OJHAS Vol. 7, Issue 2: (2008
A Comparative Analysis of Bacterial Growth with Earphone Use
Chiranjay Mukhopadhyay, Soham Basak, Soham Gupta, Kiran Chawla, Indira Bairy
Department of Microbiology,
Kasturba Medical College, Manipal - 576104
Dr. Chiranjay Mukhopadhyay,
Address For Correspondence
Department of Microbiology,
Kasturba Medical College,
Mukhopadhyay C, Basak S, Gupta S, Chawla K, Bairy I. A comparative analysis of bacterial growth with earphone use. Online J Health Allied Scs.
Submitted: May 5, 2008; Accepted:
June 17, 2008; Published: July 21, 2008
Recently the worldwide usage of earphones has increased especially among
the school and college students who have a high rate of sharing among
them. Alike airline headsets, headphones and stethoscope ear-pieces,
ear phones can easily be a vector of potential pathogens, which can
give rise to otitis externa.
Purpose: To compare
the bacterial growth of the external ear in association with earphone
and assess the role of earphones as vector or microorganisms.
Material and Methods:
50 voluntary male subjects (age 18-25 years) were chosen and divided
into two groups, A and B, according to the use of earphones. Swabs were
taken from their left ear and the left earpiece of the earphone. Samples
were processed as recommended.
In group A, bacteria were found in 20 (80%) ear and 14 (56%) earphone
swabs. In group B, bacteria were found in 23 (92%) ear and 17 (68%)
earphone swabs. Group B showed heavy growth and a significant increase
in the number of bacterial growths after frequent and constant use.
Frequent and constant use of earphones increases the bacterial
growth in the ear and sharing of earphones might be a potential vector
of commensals. It is therefore, always better not to share or else to
clean the earphones before sharing.
profile, ear, earphone, student
The external auditory
canal normally harbors many bacterial colonies which form the normal
commensal bacterial flora of the ear. They are predominantly non-pathogenic
and mostly aerobic, which include Staphylococci (like Staphylococcus
auricularis, Staphylococcus epidermidis, Staphylococcus capitis
and occasionally Staphylococcus aureus), Coryneforms (like
Turicella otitidis)1, alpha hemolytic streptococcus2,
Pseudomonas aeruginosa 2,3
and some species of micrococcus.4
Otitis externa is actually
a collection of disorders of the external auditory meatus. Otitis externa
can be divided into four types - namely acute diffuse, acute localized,
chronic and invasive otitis externa. It is principally caused by
Pseudomonas aeruginosa and Staphylococcus aureus. Heat, retained
moisture, desquamation and maceration of the epithelium add to the disease
condition.5 There are some reports on airline headsets7,
headphones8 and stethoscope ear-pieces9 where
there was a positive relationship between the usage of headphones or
stethoscopes and the occurrence of otitis externa. Recently the worldwide
usage of earphones has increased due to the gaining popularity of mobile
phones, portable music and MP3 players. Apple has sold more than 40
million iPods since they hit the market in 2001.6 Majority
of school or college students have a right rate of sharing among them
and the practice of cleaning the earphones properly before use is not
at all in vogue. People have raised concerns over the fact that it causes
hearing damage, but extensive Medline search (PubMed) showed that no
study so far has been done with earphones as a bacterial growth inducer
and a possible vector of commensals. The aim of the study was to determine
the association of constant and frequent use of earphones with bacterial
growth inside the ear and the potential role of earphones as vector
male medical students, who were not yet exposed to the hospital
environment, volunteered for the project as healthy individuals. Each
volunteer signed an informed consent form and filled up a questionnaire.
Observable signs of infection that were looked for in the ear canal
include swelling and reddening of the ear canal, discharge and foul odour of the ear canal. Symptoms included itching, pain and tenderness
upon manipulation of the pinna and feeling of fullness in the ear. Only such
students were included in the study who did not have any such signs or
symptoms. Swabs were
collected from the left ear and the left ear piece of the earphone.
They were divided into
two groups of 25 each. Group A subjects were students of ages 18 to
25 years (average 21 ± 2.2) who infrequently use or never use earphones. In this group, the swabs (ear and earphones) were collected
at random. The group B subjects were students aged 18 to 25 years (average
20.84 ± 2.5) who used to listen music with earphone constantly and
always at a stretch of at least 30 minutes. The swabs (ear and earphones)
were collected immediately after earphone usage.
The swabs were inoculated
in sheep blood agar and incubated aerobically overnight at 37oC and
the bacteria were identified according to the recommended procedure.10
The data were analyzed
using SPSS 15 for windows. The different variables were tested and the
test of significance was done using chi square test.
A total of 43 ear samples
(86%) and 31 earphone samples (62%) showed bacterial growth, ranging
from very scanty to heavy. In Group A, 20 samples (80%) from ear and
14 samples (56%) from earphones, and in Group B, 23 samples (92%) from
ear and 17 samples (68%) from earphones had growth (Table 1). In Group
A, 10 (40%) and in Group B, 14 (56%) used to share their earphones with
other students. The bacteria were identified to be methicillin sensitive
coagulase negative Staphylococcus (MSCONS) from 73 samples (73%), alpha-haemolytic
Streptococci from 10 samples (10%), Corynebacterium spp. from 7 samples
(7%) and Acinetobacter baummannii from 1 sample (1%) (Table 1).
In Group B, growth was heavy (>105 CFU/ml) in 96%
(24/25) students, whereas in Group A, growth was scanty (101 - 102 CFU/ml) in 64% (16/25) or moderate (103
- 104 CFU/ml) in 36% (9/25) students.
The distribution of isolates in Group A and B (ear and earphones)
Group A (n
Group B (n
MSCONS - Methicillin
sensitive coagulase negative staphylococcus, αHS - alpha haemolytic streptococcus.
In both groups, the growth
in the earphone sample always simulated with the growth from the corresponding
external ear as confirmed by biotyping and antibiogram. Group B students
showed a significant increase (p <0.05) of bacterial growth obtained
from the earphone samples (68% as compared to 56% of Group A) as well
as from the external ear samples (92% as compared to 80% of Group A).
The use of headphones
and stethoscopes has been studied as a potential cause of aural hygiene
problems and infection in the ear canal 1,2,5. Earphone usage among
the students has been increased in last few years. Alike headphones or
earplugs, it could have been a possible predisposing factor for external
ear infection since its continuous use can increase the temperature and
humidity of the canal, create the potential for skin abrasion and
provide a vehicle for the introduction of organisms into the canal skin
as well. The majority of the isolates were Staphylococcus spp.
(MSCONS) which although a normal skin flora most often, could well be
a pathogen if the condition is congenial. Cheaper quality or improper
use may give rise to abrasion, leading to breakage of the skin which
might be a portal of infection. It might be speculated that if the earphones are also used in the hospitals during leisure hours, it
might give rise to colonization of potential pathogens that may be drug
resistant on some occasions. The significantly higher bacterial growth (ear and
earphones) in Group B indicates a positive relationship between
bacterial growth, and frequency and duration of use of earphones. The incidence of greater colonization
with continuous and regular use of earphones is a significant finding
of this study, which shows that infrequent and intermittent use may reduce colonization
rate probably contributing to less incidence of otitis externa. The
findings correspond well with the other similar studies with the stethoscope1 and the airline headset2 where Staphylococcus
was the commonest isolate (63.89 % and 55% respectively).
It can be concluded that
bacterial transfer does increase with frequent and continuous use and
the chance of it being transferred is high while people tend to share
earphones while listening to music. This may increase a chance of otitis externa
as well especially if there is any abrasion in the external ear. The cleansing of the diaphragms
of the stethoscopes with alcohol has been shown to reduce the colonization
rate and the same procedure can be adopted to prevent transmission of
colonization flora from one to another when earphones are exchanged.
It is suggested therefore not to share
earphones or to share with caution, like cleaning it before giving it
to or taking it from someone else. This pilot study would be a healthy base for
future hospital and community based epidemiological studies of studying the role
of earphones in bacterial growth in ears.
We acknowledge the helpful
attitude and spontaneous participation of all the volunteers in the
study and the laboratory technicians who helped in sample processing.
and design of the study, and manuscript writing
of data and sample, and manuscript writing
processing and interpretation in laboratory
and interpretation of data, and manuscript writing
IB: Final approval
of the version to be published
Source(s) of support
in the form of grants, equipment, drugs, or all of these and Conflict of Interest:
Support and Conflict of interest:
- Stroman DW, Roland PS, Dohar
J, Burt W. Microbiology of Normal External Auditory Canal. Laryngoscope
- Brook I. Microbioloical Studies
of the Bacterial Flora of the External Auditory Canal in Children. Acta
- Clark WB, Brook I, Bianki
D, Thompson DH. Microbiology of Otitis Externa. Otolarungol Head Neck
- Normal Microbial Flora of
the Human Body. In: Brooks GF, Butel JS, Morse SA et al editors - Jawetz,
Melnick and Adelberg's Medical Microbiology, 23rd ed.,
New York : McGraw Hill, 2004:196-7.
- Rubin MA, Gonzales R, Sande
MA - Infections of the Upper Respiratory Tract. In: Kasper DL, Fauci
AS, Longo DL, Braunwald E, Hauser SL, Jameson JL et al editors - Harrison's
Principles of Internal Medicine. Volume I, 16th ed. New York:
- USA TODAY - Tech Products
- For iPod users, a budding problem. Available at
(accessed on Mar 21 2008)
- Brook I. Bacterial Flora of
Airline Headset Devices. Am J Otolaryngol 1985;6:111-4.
- Mazlan R, Saim L, Thomas A,
Said R, Liyab B. Ear Infection and Hearing Loss amongst Headphone Users.
Malaysian Journal of Medical Sciences 2002;9:17-22.
- Brook I. Bacterial Flora of
Stethoscopes' Earpieces and Otitis Externa. Ann Otol Rhinol Laryngol
- Koneman EW, Allen SD, Janda
WM, Schreckenberger PC, Winn WC. Color Atlas and Textbook of Diagnostic
Microbiology. 5th ed. Lippincott, NY; 1997