MEDICAL INTELLIGENCE
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rural alterations of the follicular basement membrane in
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Electron dense deposits in the follicular basal lamina of obese
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Department of Pathology University of Maryland School of
Medicine
10 South Pine Street Bahimore, Maryland 21201 (Dr.
Shamsuddin)
Medical Intelligence
OSTEOMYELITIS OF A BONE GRAFT OF THE MANDIBLE WITH ACANTHAMOEBA
CASTELLANil INFECTION
DENNIS BOgOCHOVITZ, M.B., B.Ctt., F.F. PA~rH. (S.A.),* A. JoHn
~IARTINEZ, M.D.,I"
A,xn GARY T. PATrERSOY, D.M.D.~:
Abstract
An ameloblastoma of the right side of the mandible was resected
in a 32 year old prediabetic female. An iliac crest autograft
became infected and a seqnestrum was removed seven weeks later.
Pathologic examination of this tissue demonstrated a mixed infec-
tion, including Acantbamoeba casteIlanii. This is the first
recorded instance of h~vasion of bone by a free living ameba.
Despite the ubiquity of free living amebae in the environment,
they are rarely observed in human infec- tion.~. 2 In recent
}'ears, however, it Ires become apparent that there are two genera
that may be pathogenic to man and ustmlly fatally so? 5 The first
to be recognized was Naegleria, which is a free living ameba found
in heated swimming pools and man-made lakes? This organism in-
fects man via the olfactory neuroepithel ium, causing fatal
meningoencephalitis. There have been over 150 reported cases,
ustmlly occurring in otherwise heahhy individtmls who acquire tltg
infection while swimming in unchlorinated or poorly chlorinated
man-made swimining facilities. The other type that infects man is
Acantimmoeba of wliich th[~re are a number of species. Acanthamoeba
spp. have been
Accepted for publication August 30, 1979.
*Clinical Assistant Professor, Department of Pathology,
University of Pittsburgh School of Medicine. Assistant Pathologist,
Montefiore Hospital, lfittsburgh, l'ennsylvania.
tPrafessor, Department of l'athology, University of Pittsburgh
School of Medicine. Neuropathologist, Presbyterian-University
llospital of Pittsburgh, Pittsburgh, Pennsylvania.
:~Resident, Department of Oral and Maxillofacial Surgery,
University of Pittsburgh School of Medicine and Presbyterian-
University ttospital of Pittsburgh, Pittsburgh, Pennsylvania.
isolated from the air, from the nasal passages and oro- pharynx
in normal individuals, from a purulent ear dis- charge, and from
corneal tllcers. 614 In a recent review of the l iterature only few
instances of human infections due to Acanthamoeba spp. worldwide
were found?' z5-22 A quite different epidemiology was suggested in
that this infection was found to occur probably as an opportunistic
infection in the compromised host. The primary focus of infection
also differs, being skin, conjtmctiva, and probably upper
respiratory tract with subsequent dissemination and en- cephalitis
with a fatal outcome. These patients may be healthy, but they
include diabetic patients with skin nlcers, alcoholic patients with
cirrhosis of the liver, and patients taking steroids and broad
spectrttnt antibiotics or receiving radiotherapy.
Bone is not a tissue receptive to invasion by amebae in genera l
: ~ In 1954 Bell et al. z4 reported a much quoted case of a patient
with amebic colitis, amebic liver abscess, and subsequent chronic
osteomyelitis of the right scapula. En- tamoeba histolytica was
observed in the colon and jn tlie liver abscess. Despite
preoperative examination of the draining sinus attd pathologic
examination of the scapulectomy pecimens, amebae were not found.
This case must thus be considered unproven. In 1892 Dr. Sinmn
Flexner z5 report- ed a patient, "a Virginian male aged 62 with an
abscess on the floor of the mouth." The pus was drained from this
abscess and revealed underlying necrotic bone; it "was particularly
offensive, suggesting fecal inatter." On direct microscopy it
showed "a large nuntber and variety of bacteria" and "mixed with
the, pus ce l ls , . . , larger cells possessing the power of
altering their forms . . . . and recog- nized as amoebae." With
commendable catttion (anti some foresight?) Dr. Flexner suggested
tlmt these amebae were of an "allied species i'f not identical" to
that described in amebic dysentery. We have been unable to find
an}" oil ier documented example of amebic infection with bone in-
voh'ement.
This report concerns a 32 }'ear old female in wltom an
ameloblastoma was resected from the right side of the mandible. An
autograft from the right iliac crest was used to fill the defect.
Acute suppurative osteomyelitis of the
HUMAN PATHOLOGY - - VOLUME 12, NUMBER 6 June 1981 573
HUMAN PATHOLOGY- -VOLUME 12, NUMBER 6, June 1981
graft developed and a sequestrum was removed during the
debridement procedure. Examination of the removed spec- imen
revealed gram positive cocci and gram positive and gram negative
bacilli; Acanthamoeba castellanii was observed and cultured.
CASE REPORT
The patient was a mildly obese, 32 }'ear old Caucasian female
who was admitted in January 1979 for treatment of an expansile mass
in the right mandibular area. It had been present and slowly
enlarging for two years. There was a questionable history of
diabetes mellitns controlled by diet alone; the patient's mother
had maturity onset diabetes.
The physical examination revealed a grossly obese white female
with a unilateral right mandibular facial swelling. The rest of the
general physical examination was noncontributory. The oral
examination revealed an ex- pansile firm mass extending front the
first mandibular right bicuspid area (mental foramen) to the gonial
angle of the the ascending ramus. Tbe skin overlying the lesion and
the related mucosa were both intact. The patient revealed no
symptoms except that the teeth in that area displayed mobility.
Roentgenographic examination revealed a radio- lucency that was
well circumscribed and was associated with an impacted third molar
tooth; a punch biopsy demonstrat- ed ameloblastoma.
The patient was taken to surgery and a right subman- dibular
incision (extraoral approach) was used to remove the lesion en bloc
with the related teeth. The mucosa was closed, and an autogenous
bone graft from the right superior iliac crest was taken and
positioned with interos- seous wire fixation. The periosteum was
closed around the graft and the wountl closed. The patient was
placed into intermaxil lary fixation and given clear liquid
feedings with multiple vitamin supplements. The patient received
Kellin elixir, 500 mg. orally four times daily, for 10 days as a
routine part of this procedure. The postoperative recovery was
uneventfld and she was discharged afebrile on the eleventh
postoperative clay.
The patient remained asymptomatic for five weeks following
discharge, at which time she presented to the emergency room with
acute right snbnmndibular cellulitis without intraoral or extraoral
fenestration. A Panorex roentgenogram indicated an intact bone
graft. She was afebrile. She was given 1.2 x 10 ~ units of procaine
penicillin G and 6000,000 units of aqueous penicillin G intramus-
cularly, with 500 nag. Penicillin V orally four times daily for 10
days.
The cellulitis failcd to resolve after one week and she was
readmitted. On examination she was afebrile, the intermaxil lary
wires were in place, and the oral mucosa was pink with dehiscence
overlying the mandibular graft site. The right snbmandibular area
showed diffuse cellulitis with an external fistula, which exhibited
a feculent smelling, thick purulent material. The white cell count
was 7200 per cu. ram. with a normal differential. Enterobacter
aerogenes and light microaerophilic Streptococcus pyogenes were
cul- tured from the area. Under general anesthesia the wound was
opened extraorally. Examination of the graft site revealed a large
sequestrum of necrotic bone, 4.0 by 1.5 by 1.0 cm., representing
about one-half of the autograft. The scquestrtnn was removed, the
communicating intraoral- extraoral fistulous tract was closed, and
the entire area was debrided and irrigated with betadine solution
(povidone- iodine 1 per cent). The mucosa was closcd, the
periosteum was rcpositioncd around the remaining portion of the
574
graft, and the skin was closed. Penicillin G, 2 x 10 ~ units
intravenously every four hours, was instituted and betadine
mouthwash was used four times a day. Postoperatively she did well
and was discharged on the fifth hospital day.
PATHOLOGY
The specimen was a roughly rectangular portion of bone 5.0 by
2.0 by 0.5 cm. It was white-yellow with focal areas of hemorrhage.
A thin purulent exudate covered many areas of the foul smelling
tissue. The specimen was fixed in 10 per cent bnffered fornmlin and
decalcified in nitric acid with aerosol. The tissue was sectioned
and stained with hematoxylin and eosin, trichrome, Grocott silver
methenamine, periodic acid--Schiff, and the Brown- Brenn
modification of the Gram stain.
Microscopy shows necrotic bone with necrotic marrow spaces. In
ninny of the spaces acnte inflammatory exudate is seen in
association with large groups of bacterial colonies (Fig. I).
Sntall groups of trophozoites are identified in clusters and
intimately associated with some bacterial colo- nies (Fig. 2). Some
of these can be seen to contain vacuoles in which phagocytized
debris is seen. The amebae appear to be acting in the role of
scavengers and can be seen ap- parently engaging in phagocytosis of
both cocci and bacilli attd also erythrocytes. Nowhere do the
trophozoites appear in direct contact with the host bone but appear
rather to be intimately associated with the bacterial colonies
present (Fig. 1). The trophozoites are large, measuring
approximately 20 to 40/x in diameter. Each exhibits a well defined
ectoplasm enveloping the granular endoplasm. The latter is replete
in vacuoles of various sizes and shapes containing cell debris,
bacteria, erythrocytes, and occasion- all}' a leukocyte. The
nucleus is single and central or slightly eccentric and shows a
thick nuclear membrane. A dense large central polymorphous
karyosome is a distinguishing feature, and this is separated from
the nuclear membrane by a relatively clear, chromatin free
Imlo.
Tissue sections were submitted to Dr. E. Willaert of the
Veterans Administration Hospital in Gainesville, Florida, who
performed indirect immunoflnorescence for Acantha- moeba spp.,
NaegleHa fowleH, and Entamoeba histolytica. 2~" ~r The trophozoites
were identified as Acanthamoeba castellanii. The thyoglycollate
broth was retrieved from the Bacteriolo- gy Laboratory and sent to
Dr. G. S. Visvesvara, Center for Disease Control, Atlanta, Georgia,
who cuhnred Acantha- moeba castellanii from that broth. ~
DISCUSSION
The oral cavity is the site of many microbial commen- sals.
These include bacteria of many genera (Neisseria spp.,
Streptococcus viridans). Most do not invade the tissues of the
mouth. In rare instances, however, commensals may act as
opportunists and invade the tissue. Actinomyces israelii is an
example.
Free living amebae have r6cently been recognized as oral
commensals albeit of a transient nature. 7~~ The}" are carried by
air or dust into the upper respirator}' tract and mouth in the form
o~r cysts. It is not known what factors promote excystation or
whether indeed this occurs in the oral cavity of the normal host.
It is possible that an alteration in bacterial flora, local tissue
danmge, or an imntunologically altered host all play a role in this
phenom- enon. Ahhough major oral surgery of the type experienced by
this patient is a frequent event in modern medical practice, this
is the first recorded example of invasion of the
HUMAN PATHOLOGY- -VOLUME 12, NUMBER 6, June 1981
wound and bone graft by Acanthamoeba, despite tbe ubiquity of
free living ameba.
Possible factors that play a role may be an alteration of the
bacterial flora, probably related to the broad spectrum antibiotic
used. Tiffs allowed the proliferation of gram negative bacilli and
gram positive cocci, with infection, and then superinfection by the
Acanthamoeba. However, pa- tients such as ours routinely receive
antibiotics in the postoperative period so that other factors must
sttare the responsibility. One such factor is the altered
immunologic competence of the host. The patient is a prediabetic
and Acanthamoeba infection has been reported in diabetics, t6 This
too cannot be the entire explanation. There must be man)' diabetic
patients wbo have harbored Acanthamoeba cysts transiently in the
oral cavity and, indeed, have under- gone oral surgery complicated
by bacterial infection. The conclusion is that all the foregoing
factors, acting in concert on the patient and the parasite,
resulted in a breakdown in their relationslfip and in tissue
invasion. It is also possible that there has been a recent change
in the Acanthamoeba population, resulting in a more aggressive
variety or race of Acanthamoeba. This occurs in microbes in
general, one good example recently the subject of an excellent
review being tbat ofSenatia marcescens, which from being a curiosi-
ty has evolved over the )'ears to become a serious opportun- istic
pathogen? ~ In view of the uniformly fatal outcome of Acanthamoeba
infection once systematized, a diligent search for these organisms
in possible sites of invasion should be made in biopsy material
from sites that have been reported as primary ports of entry (ear
discharges, corneal infections, skin ulcers, and, now, necrotic
infected oral tissue). In this respect it is critical for the
morphologist to be cognizant of the appearance of the trophozoites,
especially m severely damaged, often necrotic tissue, where they
may be overlooked as degenerated bistiocytes.
SUMMARY
We present a case of osteomyelitis of a mandibular bone graft,
witb superinfection by Acanthamoeba castellanii, in a patient in
whom a number of host resistance factors were impaired. However,
the possibility is raised that free living amebae, like other free
living organisms in tbe past, have become more aggressive. Only
careful examination of suspect tissnes in susceptible patients will
allow early detec- tion of such a phenomenon.
Acknowledgments
The authors gratefully acknowledge the contributions of Dr. E.
Willaert and Dr. G. Visvesvara.
Dr. George C. Sotereanos, Director of Oral and Max- illofacial
Surgery, Presbyterian-University Hospital, operat- ed on this
pattent and kindly consented to our report.
Dr. Robert E. Lee, Director of Laboratories,
Presbyterian-University Hospital, kindly drew our attention to the
report in 1892 of Dr. Simon Flexner. 25
The authors wish to tbank Linda Shab for photgraphic work and
Gustine Lewis for secretarial assistance.
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Pathology Department Mmltifiore 1 tospital 3t59 FiIHt Avenue
Pittsburgh, Pennsylvania 15213 (Dr. Borochovitz)
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