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Original Research—Otology and Neurotology
Malignant Otitis Externa: Evolving
Pathogens and Implications for Diagnosis
and Treatment
Otolaryngology–
Head and Neck Surgery
2014, Vol. 151(1) 112–116
American Academy of
Otolaryngology—Head and Neck
Surgery Foundation 2014
Reprints and permission:
sagepub.com/journalsPermissions.navDOI: 10.1177/0194599814528301
http://otojournal.orgCandace E. Hobson, MD
1
, Jennifer D. Moy, MD
1
,
Karin E. Byers, MD
2
, Yael Raz, MD
1
, Barry E. Hirsch, MD
1
, and
Andrew A. McCall, MD
1
No sponsorships or competing interests have been disclosed for this article.
Abstract
Objective.
Malignant otitis externa (MOE) is an invasive infection
of the temporal bone that is classically caused by
Pseudomonas
aeruginosa
. Increasingly, however, nonpseudomonal cases are
being reported. The goal of this study was to evaluate and com-
pare the clinical presentation and outcomes of cases of MOE
caused by
Pseudomonas
versus non-
Pseudomonas
organisms.
Study Design.
Retrospective case series with chart review.
Setting.
Tertiary care institution.
Subjects and Methods.
Adult patients with diagnoses of MOE
between 1995 and 2012 were identified. Charts were
reviewed for history, clinical presentation, laboratory data,
treatment, and outcomes.
Results.
Twenty patients diagnosed with and treated for MOE
at the University of Pittsburgh Medical Center between 1995
and 2012 were identified. Nine patients (45%) had cultures
that grew
P aeruginosa
. Three patients (15%) had cultures that
grew methicillin-resistant
Staphylococcus aureus
(MRSA). Signs
and symptoms at presentation were similar across groups.
However, all of the patients with
Pseudomonas
had diabetes,
compared with 33% of MRSA-infected patients (
P
= .046) and
55% of all non-
Pseudomonas
-infected patients (
P
= .04).
Patients infected with MRSA were treated for an average total
of 4.7 more weeks of antibiotic therapy than
Pseudomonas
-
infected patients (
P
= .10). Overall, patients with non-
Pseudomonas
infections were treated for a total of 2.4 more
weeks than
Pseudomonas
-infected patients (
P
= .25).
Conclusions.
A high index of suspicion for nonpseudomonal
organisms should be maintained in patients with signs and
symptoms of MOE, especially in those without diabetes.
MRSA is an increasingly implicated organism in MOE.
Keywords
malignant otitis externa, necrotizing otitis externa, methicillin-
resistant
Staphylococcus aureus
, MRSA,
Pseudomonas aerugi-
nosa
, otitis externa
Received September 3, 2013; revised January 16, 2014; accepted
February 26, 2014.
Introduction
Malignant otitis externa (MOE) is a potentially life-threatening
osteomyelitis of the temporal bone that can extend to involve
the surrounding soft tissues, cranial nerves, and adjacent skull
base. Elderly, diabetic, or immunocompromised patients are
most frequently afflicted. In 1959, Meltzer and Kelemen
1
first
described this infection in a case report of a patient with dia-
betes with fatal temporal bone osteomyelitis that originated
from otitis externa. Cultures from their patient’s ear grew
Bacillus pyocyanea
, which is now known as
Pseudomonas
aeruginosa
. In 1968, Chandler
2
coined the term ‘‘malig-
nant otitis externa’’ to describe this morbid pseudomonal
infection. Since then, the presence of
Pseudomonas
in
affected ears has been thought to be one of the hallmark
features of this disease.
3
It was not until 1982 that the first case of nonpseudomonal
MOE was reported. In that report, Bayardelle et al
4
described
a case of MOE due to oxacillin-sensitive
Staphylococcus
aureus
. Since then, there have been multiple reports of
S
aureus
as the sole offending organism in MOE.
5,6
There have
been few reports of methicillin-resistant
S aureus
(MRSA) as
the causative pathogen in MOE
7,8
; however, the overall inci-
dence of MRSA skin and soft tissue infections has been rising
steadily.
9
Additionally, although earlier reports revealed
P aer-
uginosa
as the causative organism in most cases of MOE,
1
Department of Otolaryngology, University of Pittsburgh Medical Center,
Pittsburgh, Pennsylvania, USA
2
Department of Medicine, Division of Infectious Diseases, University of
Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
This article was presented as a poster at the 2013 AAO-HNSF Annual
Meeting & OTO EXPO; September 29 to October 3, 2013; Vancouver,
British Columbia, Canada.
Corresponding Author:
Andrew A. McCall, University of Pittsburgh, Department of
Otolaryngology–Head and Neck Surgery, 203 Lothrop Street, Suite 500,
Pittsburgh, PA 15213, USA
Email:
mccallaa@upmc.eduReprinted by permission of Otolaryngol Head Neck Surg. 2014; 15(1):112-116.
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