7. This patient contracted
a nocardiosis infection of his right
upper arm due to gram-positive
Nocardia brasiliensis
bacteria resulting in formation of
an actinomycotic mycetoma.
There is cellulitic inflammation of
the upper arm with multiple
draining sinuses.
Overall, 80% of nocardiosis cases
present as invasive pulmonary
infection, disseminated infection, or
brain abscess. Remaining 20%
present as cellulitis. Image courtesy
of: Dr. Libero Ajello, CDC Public
Health Image Library.
12. This anteroposterior radiograph shows
involvement of the distal humerus in a case
of actinomycotic mycetoma. The causative
agent was Gram-positive bacterium
Nocardia asteroides. Note the swelling of soft
tissues as well due to cellulitis. Cutaneous or
skeletal involvement is rare in N. asteroides
infection.
Overall, 80% of nocardiosis cases present
as invasive pulmonary infection,
disseminated infection, or brain
abscess; 20% present as cellulitis.
Severely immunocompromised persons are
at greatest risk for nocardiosis. These
include persons with connective tissue
disorders, malignancy, HIV infection,
pulmonary alveolar proteinosis, alcoholism, or
high-dose corticosteroid use. Image courtesy
of: Dr. Libero Ajello, CDC Public Health Image
Library.
13. This photomicrograph of Gomori and H&E-
stained tissue sample shows three granules of
the fungus Acremonium falciforme.
A. falciforme fungus is a causative agent for the
disease in humans known as eumycotic white
grain mycetoma, a chronic granulomatous
inflammation mainly affecting the cutaneous
and subcutaneous tissues, but has been found
to also infect the eye (keratitis),
nails (onychomycosis), and if systemically
disseminated, can infect the
heart (endocarditis), brain (meningitis),
bones (osteomyelitis), and abdominal
cavity (peritonitis).
Immunocompromised individuals, such as
those with AIDS, or undergoing chemo- or organ
transplant therapy, are most susceptible due to
the opportunistic nature of this organism. Image
courtesy of: Dr. Arvind A. Padhye, CDC Public
Health Image Library.
14. This GMS-stained photomicrograph of
a granule from
a mycetoma shows filamentous structure of
the causative agent Acremonium species.
A mycetoma is a chronic granulomatous
inflammatory reaction, usually involving
the cutaneous and subcutaneous tissues of
the foot. The disease is normally acquired
by agricultural workers who suffer repeated
minor trauma, thereby, allowing the fungal
spores an entry way into the subcutaneous
tissues. Image courtesy of: Dr. Libero Ajello,
CDC Public Health Image Library.
15. This is a photomicrograph of an unidentified
tissue specimen that was harvested from a
patient with black-grain mycetoma caused by
the fungal organism Exophiala jeanselmei. A
single granule surrounded by suppurative
inflammation is depicted. Image courtesy of:
CDC Public Health Image Library.
16. This is a photomicrograph of a subcutaneous
tissue sample from a patient with black grain
eumycotic mycetoma. The causative agent
was the fungal organism Curvularia
geniculata. Numerous pigmented
granules can be seen.
Differential Diagnosis: The differential
diagnosis of mycetoma
includes sporotrichosis,
chromoblastomycosis, blastomycosis, and
certain mycobacterial infections;
botryomycosis (caused by commonly
encountered bacteria including Staphylococcus
aureus and Pseudomonas aeruginosa);
and pseudomycetoma caused by
dermatophytes.
Diagnosis: The diagnosis can be done
with tissue biopsy supplemented by culture,
morphologic assessment, biochemical
studies, mass spectrometry, quantitative
PCR and next-generation DNA sequencing.
Image courtesy of: Dr. William Kaplan, CDC
Public Health Image Library.
17. This photograph depicts various
sized phaeoid granules of the fungus
Madurella grisea. The granules, which
are discharged through multiple draining
sinuses of the mycetoma, are composed
of matted masses of dark-walled, septate,
branching hyphae. The fungus enters the
human body via repeated, usually
occupation-related trauma, and most
commonly involves the foot. The disease
process (mycetoma) may take years to
develop. Image courtesy of: CDC Public
Health Library.
18. Mycetomas are characterized by discharge
of granules in the exudate from multiple
draining sinus tracts. Granules are easily
spotted at low magnification in the sections
taken from infected tissues. They are present
within the area of suppuration and are
surrounded by neutrophils and palisaded
histiocytes. They are composed of a mass of
fungal hyphae or filamentous
bacteria organized within a deeply-eosinophilic
amorphous matrix (Splendore-Hoeppli
material). Multinucleated giant cells as well as
granulation tissue may surround the granules.
This Gridley-stained photomicrograph shows
detail of several granules from
a mycetoma caused by Acremonium species.
Image courtesy of: Dr. Libero Ajello, CDC
Public Health Image Library.