Streptococcus

CASE 1

• A 2 year old boy complains of pain when he swallows. His mother notices that his forehead feels very warm to the touch, and the front of his neck is tender.

• He is brought to the Emergency Department at Komfo Anokye Teaching Hospital where an examination reveals that is temperature is 38.8 degrees, he has swollen tonsils with patches of white exudate on them (see below), and he has bilateral anterior cervical lymph nodes that are enlarged and tender. No other lymph nodes are enlarged, and he has no runny nose or cough.

Questions:

    1. Which streptococcal species is most likely causing this common problem?
    2. What virulence factors of this streptococcus are responsible for its ability to survive in the pharnyx and to produce inflammation?
    3. In some patients there may be a diffuse rash ("scarlet fever") and redness of the tongue ("Strawberry" tongue). What bacterial product causes these features?
    4. How can you establish the diagnosis with certainty?
    5. Will this infection render the patient immune to further infection with this strptococcal species?
    6. What antibiotic will shorten the course of the illness and prevent complications?
    7. Is there any risks in not treating this child with an appropriate antibiotic? And if so, what are they?

CASE 2

• A 48 year old diabetic woman has a progressively enlarging area of swelling, warmth, and tenderness over the right side of her face. This illness began 2 days ago as a small tender nodule on the right cheek that has now spread rapidly in all directions. The swelling is accompanied by a fever with occasional chills. The patient's right eye is swollen shut, and there is some thin drainage from it. Also note the presence of small bullae (blisters) containing a clear, golden-colored fluid.

• The temperature is 38.3 degrees. The white blood cell count is elevated at 18,500/mm3 (normal=4,500-10,500/mm3)

• Culture blood was negative.

Questions:

    1. What is the streptococcal species that likely caused this infection?
    2. If the blood culture is negative, from where might you be able to culture the organism?
    3. Can similar infection begin on other parts of the body?
    4. Does this patient have a predisposing factor?

CASE 3

• A 6 year old girl develops a painful sore throat and fever that persists for 8 days and then slowly resolves. She is treated with an herbal preparation but receives no antibiotics.

• Three weeks later, the girl develops a fever with pain and swelling in several of her joints. The child restricts her movements because of the joint pain, but she becomes rapidly short of breath with simple physical activities.

• The child is taken to a regional hospital where she is examined and found to have a fever, warm and swollen knees and elbows with pain on passive motion, and a loud heart murmur consistent with mitral regurgitation. A throat culture is negative for group A streptococcus, but and anti-streptolysin O serology (ASO) is strongly positive.

• A diagnosis of rheumatic fever is made, and the child is treated with aspirin and a corticosteroid. After a illness of 6 weeks duration, the child eventually returns to normal health and returns to school.

Questions:

    1. Are you surprised that the streptococcus could not be isolated from the patient's throat?
    2. Is rheumatic fever an infection? If not, what causes it?
    3. Can rheumatic fever be prevented? If so, how?
    4. Are there any long-term consequences of this illness?
    5. Could the same sequence of events have followed the infection in Case 2 if the patient were not treated?

CASE 4

• A 24 year old woman completes the uncomplicated delivery of a 2.5kg baby boy. On the second post-partum day, the patient develops pelvic pain, fever, and a purulent vaginal discharge. The following day the baby becomes febrile (temperature of 39.3) and agitated.

• A lumbar puncture is perfromed on the baby. The spinal fluid has numerous neutophils and Gram-positive cocci in chains on the Gram stain. Both the baby's spinal fluid and the mother's blood grow the same microorganism. Both are treated successfully with a the same antibiotic.

Questions:

    1. What streptococcal species is most likely the cause of these two post-partum illnesses?
    2. Could this sequence of events have been prevented?