Streptococcus

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Streptococcus spp.

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Gram + Cocci

catalase -

Main human pathogens are S. pyogenes and S. pneumoniae.

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Streptococcus spp.:
Pathogenic features and Virulence

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--> M-protein – the most important virulence determinant. Allows adherence. Also functions to inhibit complement activation (is antiphagocytic) and causes neutrophil activation and degranulation (inflammation).

Hyaluronidase (spreads)

Capsule

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Streptococcus spp.:
Mode of Trabsmission

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Endogenous
Exogenous-direct contact with infected animals, aerosol inhalation, and fomite transmission.

Some carriers for some species

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Streptococcus agalactiae: Clinical Disease

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mastitis in cattle

Habitat- resides solely in mammary gland of cattle. Well adapted to mammary gland. Infection is usually subclinical

Control- antibiotics and improved milking sanitation, +/- vaccination

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Classification of Mastitis in cattle:

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Contagious / Infectious: primary reservoir is the cow udder

Environmental: sources include moisture, mud, and manure in cow housing area

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Streptococcus uberis
Strep. dysgalactiae:
Clinical Disease

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Frequent causes of mastitis in cattle

Responds to treatment

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Streptococcus suis

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Present in the tonsils, nostrils, and vagina of healthy adult carrier pigs.

Newborn pig infected during birth (transfer from vagina to oral cavity of piglet) or shortly thereafter.

Causes septicemia, fibrinous arthritis, meningitis, pericarditis, endocarditis, pneumonia in piglets <12 weeks of age.

zoonotic (meningitis in slaughterhouse workers).

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Streptococcus zooepidemicus

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Common inhabitant of the upper respiratory tract and vagina of normal horses

Primary cause of endometritis and infertility in the mare

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Streptococcus equi

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Strangles

Acute onset of fever, anorexia, depression, painful submandibular and pharyngeal lymphadenopathy with abscessation and rupture

nasal discharge

Can survive in environment and on fomites for @ 2 months.

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Clinical Disease: Strangles

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Bacterial shedding begins 4-7 days after infection and lasts for weeks. Convalescent carriers occur.

75% immune to repeat infection

intranasal immunizing vaccine

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Clinical Disease S. equi:
Bastard Strangles

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Formation of S. equi abscess in any organ or site

Clinical signs depend on region affected, but chronic weight loss or sudden death due to abscess rupture into a body cavity are common manifestations.

systemic antibiotic therapy combined with specific therapy for the abscess

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Clinical Disease S. equi:
Guttural Pouch Empyema

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often foul smelling nasal discharge, which may be unilateral

endoscopy and visualization
of pus or chondroids

Treat with antibiotics and pouch flushing

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Clinical Diease S. equi:
Purpura Hemorrhagica

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Painless pitting edema of limbs, petechial hemorrhages of mucosa, sloughing of skin

Immunofluorescence

Sequelae hypersensitivity immune-mediated vasculitis

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S. equi
Diagnosis / Treatment:

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Culture.
Isolate horse.
Disinfection of fomites ie brushes, pails.
+/- antibiotic therapy. In early stages antibiotics may prevent further development of disease and limit shedding.
+/- antibiotic treatment of exposed but asymptomatic stablemates.
Aid rupture of abscess.
Vaccination in the face of an outbreak may be beneficial.

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Streptococcus canis

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commensal of skin and mucous membranes of dogs and cats

Occasional cause of necrotizing fasciitis and septicemia in dogs and cats following skin trauma.

Rare reports of zoonotic

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S. pyogenes

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Main strep pathogen in humans

Dog can be colonized, no disease develops but they might serve as source of re-infection

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Streptococcus pneumoniae

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middle ear infections and sinusitis, pneumonia in young humans.