Lesions Associated With a Novel Mycoplasma Sp. in Stranded California Sea Lions (Zalophus californianus)
IAAAM 2002
Martin Haulena1; Frances M.D. Gulland1; Judith A. Lawrence1; Deborah A. Fauquier1; Spencer Jang2; Brian Aldridge2; Terry Spraker3; Maureen K. Davidson4
1The Marine Mammal Center, Marin Headlands, Sausalito, CA, USA; 2Veterinary Medical Teaching Hospital, University of California (Davis), Davis, CA, USA; 3Wildlife Pathology International, Fort Collins, CO, USA; 4Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA

Abstract

"Seal finger" is a potentially serious infection that may develop in people that have been bitten by pinnipeds or that have punctured their skin with blades or needles contaminated by pinniped body fluids. Recent studies have implicated a Mycoplasma as the causative agent in these infections3. Several different species of Mycoplasma have been cultured from the oral cavities of different pinnipeds including California sea lions (Zalophus californianus)2 and a Mycoplasma was thought to have complicated a viral pneumonia outbreak in harbor seals (Phoca vitulina)1. However, disease associated with Mycoplasma sp. has not been previously described in otariids.

From July 1999 to November 2001, Mycoplasma sp. was cultured from lesions found in 16 (12 male, 4 female) sea lions that had stranded along the central California coast and were brought to The Marine Mammal Center for rehabilitation. The animals ranged in age from yearling to adult and weighed between 19.5 and 174.5 kg. Eight of the animals were eventually released while the remaining eight either died or were euthanized during treatment. Of the eight animals that died, Mycoplasma sp. was thought to have contributed to the death of three animals where it was associated with severe pleuritis and necrotizing pneumonia in two animals and a septic polyarthritis in one animal. A summary of the lesions from which Mycoplasma sp. was cultured is presented in Table 1.

A moderate to severe leukocytosis characterized by a neutrophilia with a left shift was found in 12 out of 15 animals in which a complete blood count (CBC) was performed. Mycoplasma sp. was cultured from subdermal abscesses in 11 animals and from muscle abscesses in an additional two animals. The high prevalence of superficial abscesses in these animals suggests a transdermal route of introduction for the organism. Potential sources may include bites from other sea lions or it may be that Mycoplasma sp. is an opportunist found on the skin that may be introduced through a break in the epithelial barrier.

The organism was cultured on blood and chocolate agar and appeared as small, pinpoint colonies embedded into the agar approximately 3 to 6 days after swabs were plated. A pure culture of Mycoplasma sp. was obtained in 11 of the animals. Preliminary PCR and DNA sequencing results indicate that this is a novel species of Mycoplasma. An unidentified gram-negative rod was cultured with the Mycoplasma sp. in four samples. The significance of this organism is unknown.

Table 1. Summary of Mycoplasma sp. cultured from lesions in California sea lions (Zalophus californianus).

Sea lion identification

Lesions cultured

Organisms cultured

CSL 4296

Carpal joint

Pure culture Mycoplasma sp.

CSL 4698

Cervical and retropharyngeal subdermal abscesses

Pure culture Mycoplasma sp., but Pseudomonas aeruginosa, Proteus vulgaris, E. coli, Klebsiella sp. grown on postmortem culture of occipital condyles

CSL 4779

Subdermal hip abscess

Pure culture Mycoplasma sp.

CSL 4801

Lung and pleural fluid

Pure culture Mycoplasma sp.

CSL 4859

Pleural fluid and axillary muscle abscess

Pure culture Mycoplasma sp.

CSL 4945

Subdermal flipper and mandible abscess

Pure culture Mycoplasma sp.

CSL 4949

Subdermal neck abscess

Pure culture Mycoplasma sp.

CSL 4956

Subdermal neck abscess

Pure culture Mycoplasma sp.

CSL 4957

Subdermal flipper abscess and prescapular lymph node

Mycoplasma sp. and unidentified gram-negative rod

CSL 4998

Subdermal hip abscess

Mycoplasma sp. and unidentified gram-negative rod

CSL 5025

Subdermal hip abscess

Mycoplasma sp., Gemella sp., E. coli

CSL 5026

Axillary muscle abscess

Mycoplasma sp. and unidentified gram-negative rod

CSL 5027

Sublumbar lymph node

Pure culture Mycoplasma sp.

CSL 5059

Subdermal neck abscess

Pure culture Mycoplasma sp.

CSL 5070

Subdermal neck abscess

Mycoplasma sp. and unidentified gram-negative rod

CSL 5152

Subdermal hip abscess

Pure culture Mycoplasma sp.

Animals responded well to surgical lancing, flushing and insertion of drains to treat abscesses and to through-and-through sterile saline joint flushes to treat septic arthritis. Clinical improvement was noted following treatment with doxycycline and erythromycin.

Mycoplasma colonies may be easily missed on culture plates due to their small size and because it may take longer for colonies to grow than for some other bacteria. Antibiotics used to treat Mycoplasma infections may differ from antibiotics that are more routinely used to treat subdermal abscesses in other species. It is important, therefore, that clinicians are aware of their pathogenic potential in California sea lions.

References

1.  Geraci JR, DJ St. Aubin, IK Barker, RG Webster, VS Hinshaw, WJ Bean, HL Ruhnke, JH Prescott, G Early, AS Baker, S Madoff, RT Schooley. 1982. Mass mortality of harbor seals: pneumonia associated with influenza A virus 215:1129-1131.

2.  Measures L, L Parker, P McRaid, M Hammill, E Albaine. 2001. Oral mycoplasmal infections in pinnipeds-risk of "sealfinger" infection? Proceedings of the Fourteenth Biennial Conference on the Biology of Marine Mammals. Vancouver, Canada.

3.  Stadtlander CTK-H, S Madoff. 1994. Characterization of cytopathogenicity of aquarium seal mycoplasmas and seal finger mycoplasmas by light and scanning electron microscopy. International Journal of Medical Microbiology, Virology, Parasitology, and Infectious Disease (Germany) 280:458-467.

Speaker Information
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Martin Haulena, DVM, MS
The Marine Mammal Center, Marin Headlands
Golden Gate National Recreation Area
Sausalito, CA, USA


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