Cunninghamella: A Newly Recognized Cause
of Rhinocerebral Mucormycosis
ROBERT O. BRENNAN, M.D., BARBARA J. CRAIN, M.D., ARDELL M. PROCTOR, M.S.,
AND DAVID T. DURACK, M.B., D. PHIL.
Division of Infectious Diseases, Department of Pathology,
and the Clinical Microbiology Laboratory, Duke University
Medical Center, Durham, North Carolina
Cunninghamella, a zygomycete in the order Mucorales, is an
extremely rare cause of human infection. Of the five reported
cases of human disease caused by this fungus, none involved
rhinocerebral infection. Here, the authors document what appears to be the first case of rhinocerebral mucormycosis caused
by Cunninghamella bertholletiae in an elderly man who had
diabetes with sideroblastic anemia and hemochromatosis. The
disease was rapidly fatal. The mycology and classification of
this organism are presented, and the previous case reports in
the literature are reviewed. (Key words: Zygomycetes; Mucormycosis; Cunninghamella) Am J Clin Pathol 1983;
80:98-102
prompted the extraction of a left lower molar tooth, followed by oral
penicillin therapy. The patient's symptoms did not improve. Several
days later, an otolaryngologist diagnosed acute sinusitis, drained the
left maxillary sinus, and prescribed cephalexin. Symptomatic improvement lasted for only 24 hours. Follow-up examination 3 days after the
procedure revealed tenderness over the maxillary sinus and new swelling and erythema involving the left periorbital area. The patient was
referred for evaluation and management.
A diagnosis of thalassemia minor had been made in 1969 during
a routine physical examination. In 1976 the patient complained of
progressive malaise and had a hematocrit of 26%; bone marrow aspirate revealed a hypercellular marrow with erythroid hyperplasia,
ringed sideroblasts, and an increased amount of stainable iron. Sideroblastic anemia was diagnosed. This did not respond to treatment with
pyridoxine and folic acid; regular blood transfusions were begun in
May, 1979. By the time of admission, transfusion of 2 units every 3
weeks was required to maintain his hematocrit above 30%. Before
transfusion therapy investigations had revealed decreased serum ironbinding capacity with increased urinary excretion of iron following
desferoxamine administration and excessive iron stores in the liver.
Hemachromatosis was diagnosed. Intramuscular desferoxamine therapy was begun in March, 1980, and continued until admission. There
was a history of glucose intolerance, which was well controlled by diet
alone. Mild congestive heart failure was present, treated with hydrochlorothiazide and digoxin.
On admission, the patient's temperature was 38.4°C with normal
pulse, blood pressure, and respiratory rate. Physical findings included
left periorbital swelling and erythema of the nasal, molar, and temporal
areas. The left maxillary sinus was tender to palpation. Except for
conjunctival injection, the eye was normal with full range of motion,
brisk pupillary reactions, and no proptosis. There was no drainage or
discoloration in the nasal passages or oropharynx. The spleen was
palpable 4 cm below the costal margin; there was no hepatomegaly.
Results of cardiac, pulmonary, and neurologic examinations were
normal.
Blood studies revealed glucose of 287 mg/100 raL, sodium 134
mEq/L, chloride 97 mEq/L, bicarbonate 30 mEq/L, and potassium
3.9 mEq/L. Urinalysis yielded 1+ protein without glucose or ketones.
White blood count was 9,100/mm3 with 65% segmented neutrophils,
11% bands, 22% lymphocytes, and 27% monocytes, hematocrit 27%
with a MCV of 79 and a platelet count of 311,000/mm3. Other serum
values were normal except for bilirubin 2.2 mg/100 mL, SGOT 45
IU, and serum ferritin greater than 200 ng/mL. Sinus films showed
opacification of the left maxillary sinus, and computerized tomography
demonstrated changes consistent with inflammation of the left maxillary and ethmoid sinuses. No bone destruction or intracranial involvement was seen.
INFECTION OF THE CENTRAL NERVOUS SYSTEM by fungi of the class zygomycetes first was reported
by Paltauf in 1885.'° He coined the term "mycosis mucorina," which later became "mucormycosis," but did
not describe the ocular or orbital findings that are characteristic of the rhinocerebral form of the disease. This
was delayed by almost 50 years, until the second report
of cerebral involvement with mucormycosis by Gregory
and co-workers in 1943.2 These authors reported three
fatal cases of rhinocerebral mucormycosis and delineated the now well-known clinical syndrome of proptosis, opthalmoplegia, and meningoencephalitis in patients with poorly controlled diabetes mellitus.
Since the initial reports by Paltauf and by Gregory,
additional clinical experience has shown that this invasive fungal infection is not limited to diabetics, has
varied presentations, and is not uniformly fatal.6-8,9 Until
now, only fungi in the family Mucoraceae have been
isolated from patients with rhinocerebral mucormycosis. '' Here we present what appears to be the first case
report of rhinocerebral mucormycosis caused by a fungus in the genus Cunninghamella.
Report of a Case
A 70-year-old white man was admitted to Duke University Medical
Center for evaluation of sinusitus and facial cellulitis. Ten days before
admission, the patient had noted the onset of facial pain and decreased
hearing on the left side. The persistence of these symptoms for 2 days
Received September 13, 1982; received revised manuscript and accepted for publication December 30, 1982.
Address reprint requests to Dr. Durack: Box 3867, Duke University
Medical Center, Durham, North Carolina 27710.
0002-9173/83/0700/0098 $01.05 © American Society of Clinical Pathologists
98
CASE REPORTS
Vol. 80 • No. I
The patient was treated initially with nafcillin plus ampicillin, with
improvement in facial pain, swelling, and erythema. However, his
fever persisted; clindamycin was added on the third hospital day. Irrigation of the left maxillary sinus on the fifth day produced only a
small amount of serosanguinous drainage; a biopsy was performed.
The preliminary pathology report on this specimen described acute
and chronic inflammation without necrosis. Gram stain was unrevealing, and tissue was sent for bacterial and fungal cultures.
The patient's fever persisted following the drainage procedure. On
the seventh hospital day he developed mental confusion and a left
facial palsy. The left middle ear was drained for suspected otitis media
without improvement in the motor deficit. The next day he developed
decreased visual acuity in the left eye, proptosis, and a dilated, irregular, nonreactive pupil. He underwent immediate surgical decompression of the left orbit, left external frontoethmoidectomy, intranasal
antrostomy, and a Caldwell-Luc procedure. Exploration revealed necrotic, inflamed mucosa, with destruction of the left medial orbital
wall. Specimens for pathology, bacteriology, and mycology were obtained. Postoperatively, there was no improvement in the patient's
mental status or vision.
The following day the histologic sections from both sinus procedures
were reviewed and were found to contain fragments of large, nonseptate pleomorphic hyphae. On the same day, cultures from the initial
maxillary sinus irrigation were reported positive for a zygomycete of
the genus Cunninghamella. Later, material obtained during surgery
yielded the same zygomycete.
Treatment was initiated with 15 mg of amphotericin B, which was
increased by 10 mg every 12 hours. However, over the next 24 hours
the patient had a right hemiparesis and respiratory distress requiring
mechanical ventilation developed. A second computerized tomographic scan showed destruction of the left cribriform plate without
evidence of intracranial disease. A lumbar puncture revealed clear
spinal fluid containing 408 white blood cells per mm3, with 83% lymphocytes and 17% neutrophils. The glucose was 124 mg/100 mL and
the protein was 150 mg/ml. Gram stain and fungal cultures had negative results. On the thirteenth hospital day, the third day of treatment
with amphotericin B, the patient had a cardiac arrest and died.
Pathologic Findings
At necropsy, examination of the base of the skull
showed dark discoloration of the left posterior orbit, left
sphenoidal ridge, left middle fossa, sella turcica, clivus,
and posterior fossa, with softening of the posterior clinoids bilaterally. Exploration of the surgical site in the
left frontal and ethmoid sinuses revealed soft, red-black
tissue, while the mucosa in the corresponding area on
the right was normal. Microscopic examination revealed
extensive acute and chronic inflammation, hemorrage,
and necrosis. In addition, broad, nonseptate branching
hyphae were found in the left orbit, the left ethmoid
sinus, both mastoid sinuses, the sella turcica, and both
middle ears (Fig. 1).
Examination of the cerebral vessels showed a soft
white exudate covering the basilar artery. Dissection revealed similar material within the basilar artery, left internal carotid, both anterior inferior cerebellar arteries,
and both vertebral arteries (Fig. 1A). Microscopically,
many large, nonseptate hyphae were seen in the walls
and lumens of these vessels and in smaller, thrombosed
99
vessels within the pons (Fig. 2B). The meninges at the
base of the brain were thickened grossly and contained
chronic inflammatory cells, necrotic debris, and fungal
hyphae. There was ischemic infarction of the brainstem
extending throughout most of the rostral-caudal extent
of the pons (Fig. 2C). The left optic nerve was infarcted;
fungal hyphae were present within the nerve sheath.
The liver was enlarged moderately (2,250 g), and sections showed extensive accumulation of hemosiderin in
hepatocytes and bile duct epithelial cells. In addition,
there was bile duct proliferation, advanced portal fibrosis, and early micronodular cirrhosis resulting from the
extensive iron deposition. Hemosiderin deposits also
were present in the pancreas, bone marrow, thyroid,
adrenal cortex, posterior pituitary, gastric mucosa, myocardium, skin, and spleen. The bone marrow showed
a paucity of erythroid cells, as well as a heavy accumulation of hemosiderin. There was no myeloid proliferation to suggest a preleukemic state.
Mycology
The mold from the maxillary sinus drainage and
scrapings obtained antemortem grew at 25°C in 24
hours on Emmons' modification of Sabouraud's agar.
By 72 hours, the tubes were filled with a cottonlike
growth of grayish-white fungus. Lactophenol cotton blue
tease preparations showed acutely branching, irregularly
shaped, nonseptate hyphae. Conidiophores were present
with swollen, globose vesicles approximately 20 M in
diameter (Fig. 3). The conidia (or monosporous sporangiola) within the vesicles were predominantly oval, 5-7
n in diameter and echinulated. Light inoculum suspensions of the organism grew rapidly at 25°C, at 35°C,
and more slowly at 42 °C.
Susceptibility of a light inoculum of the isolate to
amphotericin B was performed in tryptose-phosphate
broth using a serial tube dilution method. The tubes
were incubated in the dark for 18 hours at 35°C. Growth
was inhibited by less than 1 iig/mL of amphotericin B.
Tissue obtained at necropsy contained organisms with
identical microscopic appearance to those specimens
obtained antemortem, and cultures yielded a fungus
with identical colonial morphologic characteristics. On
the basis of its morphologic characteristics, the fungus
was identified as a zygomycete of the family Cimninghamellaceae, genus Cunninghamella. Mating studies performed subsequently documented the species to be C.
bertholletiae, mating type (+).
Discussion
Only a handful of human infections caused by Cunninghamella have been recorded. This case report doc-
100
BRENNAN ET AL.
w
A.J.C.P. • July 1983
FIG. 1 (upper, left). A section through the left mastoid sinus shows the broad, irregular, nonseptate hyphae
characteristic of fungi in the class Zygomycetes. Methenamine silver (X400).
FIG. 2. Central nervous system involvement in rhinocerebral mucormycosis. A (lower, left). Dissection of the blood vessels at the base of the
brain shows distention of the left and right vertebral arteries, the left and right anterior inferior cerebellar arteries, the basilar artery, and the left
internal carotid artery by soft white material. B (upper, right). A section through the basilar artery shows broad nonseptate hyphae, within the
lumen and invading the endothelium of the vessel. Methenamine silver (X400). C (lower, right). A recent bilateral infarct of the base of the pons,
more severe on the left side, resulting from the occlusion of the basilar artery. Hematoxylin and eosin with Luxol fast blue (X2.5).
uments the first example of rhinocerebral mycosis
caused by Cunninghamella.
The history of unilateral sinusitis and periorbital cellulitis in an elderly person with diabetes could have suggested the diagnosis of rhinocerebral mucormycosis on
admission. However, the indolent initial clinical course,
the apparent prompt response to antibiotics, and the
absence, at first, of any characteristic necrotic exudate
all were misleading. Only after the evolution of unilateral facial palsy, proptosis, opthalmoplegia, and loss of
vision was the true pathogen identified by surgical exploration. Unfortunately, extension from the orbit into
the brain had occurred by the time of surgery, and death
followed soon.
The term mucormycosis currently is used to describe
infections caused by fungi of the family Mucoraceae,
comprised of the genera Mucor, Rhizopus, and Absidia.
Inasmuch as most cases of mucormycosis have been
caused by one of these three organisms, the choice of
this term was appropriate. However, this case demonstrates that a zygomycete from another family (Table
1) also can cause invasive disease.
All fungi of the order Mucorales, including Cunninghamella, are saprophytic in nature and reproduce sexually
Vol. 80 • No. I
CASE REPORTS
as well as asexually. Most isolates can be identified morphologically by their distinctive asexual sporangia.
Members of the family Mucoraceae are recognized microscopically by their characteristic terminal, saclike
sporangia, which envelop numerous asexual spores. In
contrast, the isolate from this patient demonstrated a
rounded, terminal vesicle, which was covered by a layer
of ovate conidia, sometimes called what some mycologists term monosporous sporangiola.1 The structure of
this conidiophore is characteristic of the genus Cunninghamella, which is a zygomycete of the order Mucorales in the family Cunninghamellaceae.
Because biochemical reactions and nutritive requirements are not helpful in the identification of the species
of zygomycetes, Weitzman and Crist proposed identification of Cunninghamella by the in vitro evaluation
of temperature tolerance.13 According to this criterion,
the fungus isolated from our patient was C. bertholletiae
because it grew at 42°C. The other member of this genus,
C elegans, will not grow in temperatures above 40°C.
Less reliable morphologic features used to separate these
two species include color of the colonies in culture, presence of echinulated conidia, aseptate hyphae, length of
conidiophores, and diameter of the vesicles.12 Because
there is some overlap of these characteristics between
C. bertholletiae and C. elegans, the only definitive mode
ofidentification is by means ofmating studies performed
with known species of Cunninghamella. These were performed on this isolate, confirming the classification of
our specimen as C. bertholletiae.
We could find no previous report of rhinocerebral
mucormycosis caused by Cunninghamella. The literature on human disease caused by this fungus is limited
to five case reports of pulmonary and disseminated infection in immunocompromised patients. The first case
of mucormycosis associated with the genus Cunningh-
FIG. 3. A branching, nonseptate hyphal fragment from culture,
showing a conidiophore bearing multiple conidia. Lactophenol cotton
blue tease preparation under phase contrast illumination (X400).
101
Table 1. Classification of those Zygomycetes known
to cause disease in humans
Class
Order
Family
Genus
Family
Genus
Family
Genus
Family
Genus
Family
Genus
Zygomycetes
Mucorales
Mucoraceae
Mucor*
Rhizopus*
Absidia
Cunninghamellaceae
Cunninghamella*
Mortierellaceae
Mortierella
Saksenaeaceae
Saksenaea
Syncephalastraceae
Syncephalastrum
• Asterisks indicate the only three genera reported to have caused rhinocerebral mucormycosis.
amella was described in 1959, in an 8-year-old boy with
lymphosarcoma, whose final hospitalization was complicated by fever, renal failure, metabolic acidosis, and
gastrointestinal hemorrhage.3 At necropsy, broad, nonseptate branching hyphae were present in histologic sections of the lungs, larynx, heart, esophagus, stomach,
and ileum. The clinical isolate was identified initially
incorrectly as a member of the family Mucoraceae because the terminal vesicle and conidia were mistaken
for sporangia. A second pediatric patient, a 13-year-old
boy with postnecrotic cirrhosis of unknown cause, in
whom Cunninghamella was isolated at autopsy from the
heart, kidney, and spleen, has been reported recently.7
This patient had a prolonged and complicated hospital
course and at necropsy also was found to have Aspergillus present in the lungs, brain, and kidney. Therefore,
the significance of the Cunninghamella isolated from
this patient is uncertain.
Three other patients with systemic infection caused
by the genus Cunninghamella have been reported.4'5'7
All had some form of hematologic disease (chronic myelogenous leukemia, chronic lymphocytic leukemia, and
one not specified). At necropsy, all were found to have
invasion of the pulmonary vasculature by broad, nonseptate hyphae, with thrombosis. Infection was limited
to the respiratory tract in two of the three patients and
was present in the liver of the third.
Weitzman and Crist recently reported the mating patterns and thermotolerance of the members of this genus. ' 2 '' 3 Of their eight clinical isolates, two were obtained
from sputa only and one from an unknown site. The
remaining five strains were from the patients reported
previously. None of these isolates was cultured from a
patient with rhinocerebral disease. In an extensive review of the literature, Swartz and associates found only
fungi of the genera Mucor and Rhizopus among the
proven etiologic agents of rhinocerebral mucormy-
BRENNAN ET AL.
102
cosis.'' We are aware of no subsequent reports of other
zygomycetes causing rhinocerebral disease. Thus, our
case report adds a new family to the short list of fungi
that can cause this serious, often fatal, form of invasive
mucormycosis.
Acknowledgments. The authors thank Marion Y. Crist of the Bureau
of Laboratories, City of New York Department of Health, for performing the mating studies on this fungus; Thomas G. Mitchell, Ph.D.,
for reviewing the manuscript; and Olive Sherman for secretarial assistance.
5.
6.
7.
8.
9.
References
1. Alexopoulos CJ, Mims CW: In Introductory Mycology. 3rd edition. New York, John Wiley and Sons, 1979 pp 191-228
2. Gregory JE, Golden A, Haymaker W: Mucormycosis of the central nervous system: Report of three cases. Bulletin of The
Johns Hopkins Hospital 1943; 73:405-415
3. Hutter RVP: Phycomycetous infection (mucormycosis) in cancer
patients: A complication of therapy. Cancer 1959; 12:330-350
4. Kiehn TE. Edwards F, Armstrong D, Rosen PP, Weitzman I:
Pneumonia caused by Cunninghamella berthiolletiae compli-
10.
11.
12.
13.
A.J.C.P. • July 1983
cating chronic lymphocytic leukemia. J Clin Microbiol 1979;
10:374-379
Kwon-Chung KJ, Young RC, Orlando M: Pulmonary mucormycosis caused by Cunninghamella elegans in a patient with
chronic myelogenous leukemia. Am J Clin Pathol 1975;
64:544-548
Lehrer RI, Howard DH, Sypherd PS. Edwards JE, Segal GP,
Winston DJ: Mucormycosis. Ann Intern Med 1980; 93:93-108
McGinnis MR, Walker DH, Dominy IE, Kaplan W: Zygomycosis
caused by Cunninghamella bertholletiae. Arch Pathol Lab Med
1982: 106:282-286
Meyer RD, Armstrong D: Mucormycosis: Changing status. CRC
Crit Rev Clin Lab Sci 1973; 4:421-451
Meyers BR, Wormser G, Hirschman SZ, Blitzer A: Rhinocerebral
mucormycosis: Premortem diagnosis and therapy. Arch Intern
Med 1979; 139:557-560
Paltauf A. Mycosis mucorina; ein Beitrag zur Kenntniss der menschlichen Fadenpilzerkrankurnen. Virchows Arch [Pathol Anat]
1885; 102:543-564
Schwartz JN, Donnelly EH, Klintworth GK: Ocular and orbital
phycomycosis. Surv Ophthalmol 1977; 22:3-28
Weitzman I, Crist MY: Studies of clinical isolates of Cunninghamella. I. Mating behavior. Mycologia. 1979; 71:1024-1033
Weitzman I, Crist MY: Studies with clinical isolates of Cunninghamella. II. Physiological and morphological studies. Mycologia 1980;72:661-669
Green Algal Infection in a Human
JERRY W. JONES, M.D., HARRY W. MCFADDEN, M.D., FRANCIS W. CHANDLER, D.V.M., PH.D.,
WILLIAM KAPLAN, D.V.M., M.P.H. AND DANIEL H. CONNER, M.D.
Infection by unicellular green algae has not been described in
humans. A case is reported in a 30-year-old woman who developed persistent infection of a healing operative wound on
the dorsum of the right foot, after possible contamination by
river water while canoeing. The wound was debrided 2 months
later. Histologically, infected tissues contained mixed suppurative and granulomatous inflammation associated with endosporulating, round to oval microorganisms, ranging from 6 9 /xm in diameter. Many of these organisms contained multiple,
strongly periodic acid-Schiff, Gomori methenamine-silver, and
Gridley fungus-positive granules in the cytoplasm. The organisms in tissue did not stain with fluorescent antibody conjugates
specific for the two known pathogenic Prototheca species. In
some organisms, electron microscopy revealed membranous
cytoplasmic profiles considered to be remnants of degenerated
chloroplasts. These findings are consistent with the presence
of a green algal infection. (Key words: Green algal infection;
Protothecosis) Am J Clin Pathol 1983; 80:102-107
UNICELLULAR GREEN ALGAE have been reported
to cause infection in animals. To date, 16 such cases
have been recognized'-7" in 11 cattle (eight from Australia" and three from the United States7), four sheep
Received September 9, 1982; accepted for publication October 1,
1982.
Address reprint requests to Dr. Jones: University of Nebraska Medical Center, Department of Pathology and Laboratory Medicine, 42nd
and Dewey Avenues, Omaha, Nebraska 68105.
Departments of Pathology and Laboratory Medicine and
Medical Microbiology, University of Nebraska Medical
Center, Omaha, Nebraska, Centers for Disease Control,
Center for Infectious Diseases, Public Health Service, U.S.
Department of Health and Human Services, Atlanta,
Georgia, and Department of Infectious and Parasitic
Disease Pathology, Armed Forces Institute of Pathology,
Washington, D.C.
(two from the United States7 and two from India*), and
a beaver.7 The cattle and sheep had been slaughtered in
veterinary-inspected abattoires, where these animals appeared healthy on antemortem examination. However,
greenish lesions in lymph nodes and internal organs were
noted on postmortem examination. Lesions in cattle
predominantly have involved retropharyngeal lymph
nodes, and lesions in sheep have involved visceral organs. The beaver had been trapped in Canada, and the
pelt contained green nodules in the dermis. The green
color of the lesions has been characteristic of green algal
infection in animals. The algae retain their intrinsic
green color in wet mounts and in smears of fresh tissue.
However, they are not green in sections of paraffin* Personal communication from F. W. Chandler, Centers for Disease Control, Atlanta Georgia.
0002-9173/83/0700/0102 $01.10 © American Society of Clinical Pathologists