This document provides information about Mycobacterium marinum, including its morphological, biochemical, and epidemiological characteristics. It causes opportunistic infections in humans and fish. In humans, it typically presents as slow-developing cutaneous lesions on areas exposed to contaminated water. In fish, it can cause chronic granulomatous disease. Diagnosis involves histopathology, staining, culturing of lesions, and PCR. Treatment involves antibiotics, sometimes with surgery. Prevention focuses on sanitation of aquariums and proper handling and cooking of fish.

1. College of veterinary
medicine
MYCOBACTERIUM MARINUM
Presenter:
Date:
SCHOOL OF GRADUATE STUDY
Dep’t of Veterinary Microbiology
By: Dr. Abdurof Mohammed

2. Outline
Introduction
Morphological and Biochemical Characteristics
Epidemiology
Clinical Sing
Histopathological Features
Transmission
Diagnosis of M. Marinum Infection
Treatment and Prevention

3. 1. Introduction
• Mycobacterium marinum formerly called M.
balnei is a free-living bacterium.
• Which causes opportunistic infections in
humans, causing chronic cutaneous lesions and
in some cases deeper infections.
• Mycobacteriosis is a chronic or acute,
systemic, granulomatous disease that occurs in
aquarium and culture food fish, particularly
those reared under intensive conditions.

4. Intro…..
• Mycobacteriosis results from infection by several
species of Mycobacterium, aerobic, Gram-positive,
acid-fast bacilli, pleomorphic rods which are
members of the order Actinomycetales and family
Mycobacteriaceae.
• Mycobacteria are widespread in the env’t,
particularly in aquatic reservoirs.
• The two most important species causing
mycobacteriosis in fish and humans are M. marinum
and M. fortuitum.

5. Intro…..
• M. marinum was first recognized in 1926 from
the liver, spleen and kidney of tropical coral
fish kept in the Philadelphia Aquarium.
• M. marinum is ubiquitous and is found
worldwide in bodies of fresh water, brackish
water and salt water.
• One survey found that more than 67% of
water specimens collected from natural,
treated and animal contact sources contained
mycobacteria.

6. 2. Morphological and Biochemical
Characteristics
1. Morphology
 Shape is pleomorphic
rods
 cell walls are thicker
 Non-motile
 Non-sporulation
 Acid-fast
 Gram-positive
 Non-branching rod
2. Characteristics
 The cell wall they have
waxy, and rich in mycolic
acids.
 The cell wall consists of the
hydrophobic mycolate layer
and peptidoglycan layer
held together by a
polysaccharide,
arabinogalactan
 The cells are straight rods
between 0.2 and 0.6 μm
wide and between 1.0 and
10 μm long.

7. Lipid-Rich Cell Wall of Mycobacterium
Mycolic acids

8. Lowenstein-Jensen media
Colony characteristics
• the colonies are apparent in
approximately 8-10 days at
25-28°C
• They are smooth, shiny and
creamy colored
• turning yellow under
exposure to light
(photochromogenic G-I).
Lowenstein-Jensen media

9. 3. Biochemical Characteristics
• Pigment production (+)
• Urease (+)
• Thiopen-2- carboxylic acid hydrazide sensitivity
(+)
• Arylsulfatase (+)
• Pyrazinamidase (+)
• Tween hydrolysis (+)
• Catalase (-) and
• Nitrate reduction (-).

10. 3. EPIDEMIOLOGY
• Mycobacterium marinum was first recognized
in 1926 from the liver, spleen and kidney of
tropical coral fish kept in the Philadelphia
Aquarium.
• M. marinum can grow prolifically within
fibroblast, epithelial cells and macrophages. In
the past, human outbreaks of M. marinum
were sporadic and most commonly associated
with contaminated swimming pools.

11. 3. EPIDEMIOLOGY
• Chlorination practices used today have greatly
minimized to frequency of outbreaks from
these sources. In the last decade, a small but
steady increase in the frequency of
Mycobacterium marinum infections in
cultured or hatchery confined fish and human
cases associated with fish aquaria has been
noted

12. 4. CLINICAL SIGNS
1. Clinical sign in human
 Incubation period is normally about 2–8 weeks.
 Mycobacteriosis infection most commonly manifests as a
cutaneous disease which can be quite variable, slow
developing and symptomatically non-specific.
 Small erythematous papules develop into granulomas,
abscesses or ulcers. Skin lesions may be single but are often
multiple, clusters; lesions may spread
 Lesion location varies depending on exposure.
 Deep tissue infections are possible and can cause considerable
damage to the underlying tissues, tendons and bone, such as
chronic proliferation of the synovial tissue, erosion of the
joints, and damage to tendons.
 Systemic dissemination is rare but cases have been reported in
immunocompromised persons and can result in death.

13. Clinical sign in human
Infections with M. marinum can be classified
into four different clinical categories to help in
guiding treatment options.
Type one: includes single or limited (1–3
lesions) superficial cutaneous infections
(erythematous, ulcerated, crusted, or verrucous
plaques or nodules). Lesions are small, painless,
bluish-red papules 1 to 2 cm in diameter,
typically these lesions are self-limited, but they
may take several months to resolve.

14. Clinical sign in human
 Type two: includes numerous >3 lesions in a
sporotrichoid distribution pattern or with inflammatory
nodules, abscesses, and granulomas. Lesions are single or
multiple subcutaneous granulomas, with or without
ulceration, the “sporotrichoid” form of M. marinum is
characterized by nodular painless, solid, livid, ulcerating
lesions that spread proximally up lymphatic to regional
lymph nodes. 20 to 66.6 % of cases had Sporotrichoid
dissemination were reported this form tends to be more
persistent and may not resolve in immunocompromised
patients.
 Type three: includes deep infections with or without
skin involvement, including tenosynovitis, arthritis,
bursitis, and/or osteomyelitis lesions are deeper infections
involving the tenosynovium, bursa, bones, or joints.
Necrotizing fasciitis.

15. Clinical sign in human
• Type four: refers to disseminated
infection, lung involvement, and other
systemic manifestations and visceral
involvements, including granulomatous
pulmonary disease due to M. marinum
found pulmonary lesion in an a nodular
lesion with infiltration in the lung and
Bacteremia is usually seen in
immunocompromised.

16. Type of lesions
• (C) Verrucous plaques on
the dorsa of the hand.
 Skin lesions. (A and B a
large area of immersed
erythema and edema
with nodules,
ulcerations, and crusts
scattered on the right
upper limb was present.
• A nummular deep ulcer
with a severe tenderness
presented on the back
side of the second digit.
C

17. Type of lesions
• M .marinum
infection mimicking
Extra-nodal ,T cell
lymphoma, auricle
showed reddish-
black appearance,
swelling, and a
painful lesion with
exposed cartilage
(A).
• The nose showing saddle
deformity with a painful
erythematous lesion (B).
• The left lower leg showing
reddish and painful nodules

18. 4. CLINICAL SIGNS
2. Clinical sign in fish
 After entry into the body, mycobacterial organisms
spread throughout the body by the circulatory or
lymphatic system.
 The infection in fish has an average incubation period
of 3 months.
 The disease may be acute or chronic.
 Acute disease characterized by uncontrolled growth of
the pathogen and death of all animals within 16 days
 The chronic form of the disease is most commonly and
characterized by granuloma formation in different
organs and survival of the animals for at least 4 to 8
weeks.

19. 2. Clinical sign in fish
Signs include
 Exophthalmos (bulging
eyes)
 Changes in
pigmentation
 Ulcerative dermal
necrosis,
 Skeletal changes
 Swollen and distended
an abdomen.
Signs include
Stunting defects and
pale gills.
Ulcers and eroded
fins and tail rot,
Skeletal deformities,
Weight loss, non-
healing open ulcers
and etc.

20. Clinical sign in fish
 A: Goldfish showing
abdominal ascitis and
erected scales.
 B: Goldfish showing
bilateral exophthalmia
 C: Goldfish Showing
emaciation, congestion
and adhesion of the
abdominal viscera at the
end point
A B
C

21. 5. HISTOPATHOLOGICAL FEATURES
• The early M. marinum lesions are similar to those of
the lesions observed in pulmonary tuberculosis
Granulomatous nodular or diffuse inflammation
with mixed granulomas, abscesses with mild
granulomatous reaction and deep dermal or
subcutaneous granulomatous inflammation, Acid
Fast Bacilli are observed in the lesions, suppurative
and granulomatous process in the dermis, with par
keratosis, acanthosis and ulceration in the
epidermis.
• Pseudo carcinomatous hyperplasia may also occur.
• The caseation is absent, but there fibroid necrosis

22. 5. HISTOPATHOLOGICAL FEATURES
M. marinum
cutaneous
infection: The
histopathology
shows a
granulomatous
inflammation
Skin biopsy - Histopathology.
(a)Pseudo carcinomatous epithelial
hyperplasia with amorphous material in
the follicular epithelium, which is
surrounded by intense infiltrates of
lichened pattern,
(b)(b) Chronic granulomatous
inflammatory reaction of tuberculosis
pattern with focus of fibroid necrosis
and absence of acid-fast bacilli

23. 6. TRANSMISSION
• The source of Mycobacterium marinum infection is
contaminated water sources.
• In fish, transmission can occur by consumption of
contaminated feed, cannibalism of infected fish or
aquatic detritus or entry via injuries, skin abrasions
or external parasites. In viviparous fishes, trans
ovarian transmission has also been reported.
• Snails and other invertebrate organism have been
show to play a role in the transmission of
Mycobacterium.

24. 6. TRANSMISSION
• In humans, breaks in the skin serve as an entry point for
the organism during contact with contaminated water
sources or infected fish.
• This is most common during cleaning or maintenance
of aquariums.
• Direct inoculation may occur following injury from fish
fins or bites.
• Less commonly, exposure can occur from contact with
natural water sources during fishing, boating or
swimming.
• Most infections occur in persons who keep an aquarium
at home, but M. marinum infection may be an
occupational hazard for certain professionals, such as
aqua culturists, fish processors, or pet shop workers.

25. 6. TRANSMISSION
M. marinum can remain viable in the environment
(soil and water) for two years or more or in carcass
and organs up to one year.
This can lead to the possible indirect transfer of the
organism, as was reported in a case of exposure
from a bathtub where the family’s tropical fish tank
was frequently cleaned and an outbreak of
mycobacteriosis in lizards kept in a contaminated
fish aquarium.

26. 7. DIAGNOSIS
Patient history
• Exposure to fish tank
• Fish
• shellfish
• salt or fish water
• swimming pools
• Characteristic skin lesion
• Nodules
• Abscesses
• ulceration especially on
the fingers and on the
hand
Specimen
collection
• Skin biopsy or aspirated pus
• Histopathology and
• Mycobacteriology laboratory
• Ziehl-Neelsen staining
• Mycobacterial cultures
• Solid media Lowenstein-Jensen
media at 30-33oC (rather than at
37oC) in 7 to 21 days.
Diagnosis of M. marinum infection

27. 7. DIAGNOSIS
Stainning
Culturing and Histological
Examination
Intradermal Skin (tuberculin skin)
Test
Polymerase Chain Reaction (PCR)

28. 8. Treatment and Prevention
 Effective therapeutic options for Mycobacterium
marinum infections.
• Spontaneous resolution
• Oral medications
• – Minocycline
• – Doxycycline
• – Trimethoprim-sulfamethoxazole
• – Clarithromycin
• – Azithromycin
• – Ciprofl oxacin
• – Amikacin
• – Rifampicin
• – Rifabutin
• – Ethambutol
• Surgical treatment
• Cryotherapy
• X-ray therapy
• Electrodesiccation
• Photodynamic therapy
• Local hyperthermic therapy
• Combination treatments
1. Treatment

29. 8. Treatment and Prevention
• Prevention measures involve sanitation, disinfection
and destruction of carrier fishes.
• Fish should be obtained from farms known to be free
of diseases.
• Imported fish should require a period of quarantine.
• If trash fish or dead fish carcasses are used as a source
of protein in the feed for fish, it should be heated at
76oC for 30 minutes to kill any pathogenic
mycobacteria.
• Dead fish should be destroyed by burning or burying in
quicklime
2. Prevention

30. 8. Treatment and Prevention
• Bandage or dress any open wound or cut before exposure.
• Clean hands thoroughly before and after exposure to aquarium water and
components.
• Hydro alcoholic solutions may be used instead of hand washing.
• Do not swallow aquarium water when checking for salinity or siphoning water.
• Do not overcrowd aquaria, since this favors the multiplication of mycobacteria.
• UV germicide lamps to treat aquarium water are efficient for mycobacteria as long
as they are used in clean conditions at the correct flow rate.
• Do not transfer tank filters or fishes in the bath that is used for humans, or carefully
clean it with sodium hypochlorite
• The exposed population should be educated in order to recognize signs of M.
marinum disease in fishes and in humans so they can inform medical staff, a point
that will expedite the diagnosis.
• Fish salespersons should be educated. Indeed, many tropical fish salespersons
ignore warnings about fish tank granuloma. In France, although 20% of them are at
risk of M. marinum infection, 95% of them immerse their hands without gloves in
the fish tanks every day.
2. Prevention