Streptococcus suis is a bacteria that commonly infects pigs and can cause zoonotic infections in humans exposed to pigs or pork. It is a leading cause of purulent meningitis. S. suis meningitis presents similarly to other forms of meningitis but has a tendency to relapse or worsen after initial antibiotic treatment. It can also cause other infections like arthritis, pneumonia, or endocarditis. Treatment involves broad-spectrum antibiotics like penicillin combined with steroids and multidisciplinary care. Prevention focuses on reducing exposure and contact with pigs for high-risk groups like farmers and butchers.

1. A D E W I J A Y A , M D – N O V E M B E R 2 0 2 2
Streptococcus suis Meningitis

2. Introduction
 Streptococcus suis, a prevalent porcine pathogen
that may sporadically causing infections in human
 S. suis was first identified as an etiological factor of
human infections in 1968
 Meningitis, sepsis, or arthritis, etc
 Main risk groups for S. suis infection are subjects
being occupationally exposed to pigs and/or pork,
for example, farmers, butchers, meat sellers,
foresters, and hunters

3. Streptococcus suis
 Heterogeneous Gram-positive
 Facultative anaerobe, spherical or ovoid in shape,
typically presents in pairs or as short chains
 Presence of alpha hemolysis on selective media
enriched with horse blood
 The lack of growth in 6.5% NaCl agar, negative result
of Voges-Proskauer test, and synthesis of acid from
trehalose or salicin are sufficient to consider an
alpha-hemolytic Grampositive coccus as a S. suis
isolate

4. Streptococcus suis
 More accurate identification requires additional
biochemical tests:
 Arginine dihydrolase (positive result)
 Production of acid from lactose, sucrose, and inulin
(positive result)
 Synthesis of acid from glycerol, mannitol, and
sorbitol (negative result)

5. Streptococcus suis
 Hosts: pig, horse, dog, cat, human
 35 various serotypes; , it is serotype 2 (SS2) that
plays a crucial role in the pathogenesis of human
infections
 four main virulence factor categories:
(1) surface/secreted elements
(2) enzymes/proteases
(3) transcription factors/regulatory systems
(4) transporters/secretion systems

6. Clinical Presentation
 Meningitis
 Similar presentation to other purulent meningitis
 However contrary to purulent meningitis of other
etiologies, infections caused by S. suis show a
tendency to relapse
 Prolonged, biphasic course with frequent incidence
of cerebellar ataxia and deafness
 Exacerbation of the symptoms is usually observed
after 2–3 weeks of first-line antibiotic therapy

7. Other Clinical Presentation
 Enteritis
 Arthritis
 Endocarditis
 Pneumonia (predominantly an opportunistic one)
 Spondylodiscitis
 Endophthalmitis
 Uveitis
 Peritonitis

8. Management
 Broad-spectrum antimicrobials, such as penicillin,
ampicillin, and ceftriaxone
 Steroid ?
 Primary prevention
 Multidisciplinary approach; ENT

9. Summary
 S. suis is an important etiological factor of purulent
meningitis, especially in subjects being
occupationally exposed to contact with pigs and/or
pork meat.
 Typical meningeal symptoms
 Biphasic; relaps
 Cerebellar ataxia and deafness
 Multidisciplinary approach

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