This case study involves a 40-year-old intravenous drug user who presented with cellulitis in the right arm along with fever and dizziness. Blood tests revealed abnormal EKG and murmur. Streptococcus pyogenes was isolated from blood cultures and identified using Gram stain and Lancefield serology. The patient was diagnosed with systemic Streptococcal infection including cellulitis, streptococcal toxic shock syndrome, and bacterial endocarditis likely resulting from repeated IV drug use. Treatment involved intravenous antibiotics and supportive care.

1. Case Study 10
Christy C
Sheila M
Sydney T

2. The Toxic Invasion of Bacteria
Streptococcus pyogenes

3. Case Summary
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Age: 40
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Intravenous drug user
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Cellulitis found in right arm with large area
inflamed and oozing
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Several weeks of experiencing fever and dizziness
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Cardiac exam shows abnormal EKG and systolic
murmur

4. DIAGNOSIS 🔬 ISOLATION 🔬
IDENTIFICATION
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Gram stain of blood culture
Gram-positive cocci in chains
Β-hemolysis on blood agar
Typable by Lancefield serology

5. Lancefield Serology
• The classification system of hemolytic Streptococci into
groups, according to their action on blood cells
• Established in the 1930s by the renowned American
microbiologist, Rebecca Lancefield

6. Lancefield Serology Classification
• Streptococci divide in one plane and thus occur in pairs
or in chains or varying lengths
• The metabolism of S. pyogenes is fermentative
• The organism is a catalase-negative, aerotolerant
anaerobe
• Requires enriched medium containing blood in order to
grow
• Group A streptococcus (GAS) typically have a capsule
composed of hyaluronic acid and exhibit beta hemolysis
on blood agar

8. Key Information Pointing to Diagnosis
• Intravenous Drug Usage
By virtue of their injecting behavior, and as a result of indirect factors
such as poor living conditions, injecting drug users (IDUs) are
particularly vulnerable to life-threatening acute and chronic infections
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Systemic symptoms of fever and dizziness
Presence of cellulitis
Abnormal EKG and systolic murmur
Gram stain of blood culture revealing grampositive cocci in chains which demonstrates
β-hemolysis on blood agar

9. Diagnosis for Case #10
• Systemic infection with Streptococci pyogenes
o Localized infection began with port of entry of IV drug injection
o Repeated usage of IV injection and non-treatment of wound resulted in bacteria
invading body tissue and contaminating blood
o Suppressed immune system due to drug usage
• Cellulitis
o A spreading bacterial infection just
below the skin surface

10. • Streptococcal Toxic Shock Syndrome
o Invasive GAS disease precipitated by bacteria colonizing at local skin
infections
o Fever
o Dizziness
• Bacterial Endocarditis
o An infection of the valves and inner lining of the heart
o Caused by bacteria from the skin entering the bloodstream and infecting the
heart

12. Virulence Factors
• M protein
o Inhibits phagocytosis
• Lipoteichoic acid
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Adherence
• Hyaluronic acid capsule
o Immunological disguise & inhibits phagocytosis
• Invasions
o Streptokinase enzyme catalyzes the conversion of plasminogen to plasmin
o Hyaluronidase enzyme that catalyzes the hydrolysis of hyaluronic acid
• Pyrogenic (erythrogenic) toxin
o Systemic toxic shock syndrome

14. Epidemiology
According to a report from the Centers for Disease
Control and Prevention (CDC)
o Approximately 9,000-11,500 cases of invasive GAS
disease occur each year in the United States
o Streptococcal TSS and necrotizing fasciitis each
accounted for approximately 6-7% of cases
o More than 10 million noninvasive GAS infections
(primarily throat and superficial skin infections) occur annually

15. Microbial Pathogenesis
Acute infections
Streptococcal pharyngitis
(strep throat)
Scarlet fever
(rash)
Impetigo
(skin infection)

16. Invasive, toxigenic infections
o Necrotizing fasciitis “the-flesh-eating-bacteria”
o Streptococcal toxic shock syndrome (STSS)

17. Post sequelae infections
Rheumatic fever
• Fever
• A red, raised, lattice-like rash, usually on the chest, back, and abdomen
Swollen, tender, red, and extremely painful joints -- particularly the
knees or ankles
• Nodules, or small protuberances, over the swollen joints
• Sometimes, weakness and shortness of breath caused by heart
involvement
Glomerulonephritis
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Fever
Restlessness
Pains
Headache
Nausea/Vomiting
Blood in the urine

18. Treatment
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Penicillin is still uniformly effective, although a
combination of penicillin and clindamycin is
recommended in the rare event that the organism is
resistant to one or the other
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Recommended duration of antibiotic therapy is 14 days
however; therapy may be individualized
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High doses of intravenous drug therapy are
recommended for those with STSS along with the
addition of supportive care in an intensive care unit
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Endocarditis requires further cardiogram testing and is
essential in monitoring and controlling the disorder

19. Prognosis
Symptomatic and functional recovery is
expected following an ongoing rehabilitation
care plan contingent upon compliance by the
patient to include completion of
antimicrobial drug therapy paired with the
improvement of personal hygiene

20. Prevention
• Through good hygiene & hand washing
• Through good house keeping
• Cover mouth or nose when coughing or sneezing
• Do NOT share personal items
• Administering proper first aid & treatment aseptically
• Stay up to date on vaccines

21. References
o Case, Funke, Tortora, Microbiology, An Introduction, Eleventh
Edition, Pearson Education, Inc., 2013
o “Group A Streptococcal.” National Center for Immunization and
Respiratory Diseases: Division of Bacterial Diseases 2008.” Centers
for Disease Control and Prevention (CDC), Disease Info:
<http://www.cdc.gov/ncidod/dbmd/diseaseinfo/groupastreptococcal_g.htm>
o Todar, PhD. Kenneth. “Streptococcus pyogenes and Streptococcal
disease.” Textbook of Microbiology 16 Oct. 2013
<http://www.textbookofbacteriology.net/streptococcus_3.html>