question archive report wrong answers be sure of your answers 1 Does aciclovir prevent the chances of developing herpes zoster (shingles) when given during primary infection? 2 How long does it take after vaccination to become immunized against chickenpox and therefore safe to work in infectious areas? 3 Is meticillin-resistant Staphylococcus aureus (MRSA) the only major hospital-acquired infection? 4 Do you have to have antibiotics to get Clostridium difficile infection? 5 Why do some patients with rheumatic fever later progress to chronic rheumatic heart disease? 6 What is the World Health Organization recommendation for the prophylaxis of rheumatic fever after a streptococcal throat infection? 7 Does rheumatic fever have an infectious or an immunological aetiology? 8 Why is migratory polyarthritis found in rheumatic heart disease? 9 Are penicillins still the drug of choice in streptococcal infections (particularly Strep
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report wrong answers be sure of your answers
1 Does aciclovir prevent the chances of developing herpes zoster (shingles) when given during primary infection?
2 How long does it take after vaccination to become immunized against chickenpox and therefore safe to work in infectious areas?
3 Is meticillin-resistant Staphylococcus aureus (MRSA) the only major hospital-acquired infection?
4 Do you have to have antibiotics to get Clostridium difficile infection?
5 Why do some patients with rheumatic fever later progress to chronic rheumatic heart disease?
6 What is the World Health Organization recommendation for the prophylaxis of rheumatic fever after a streptococcal throat infection?
7 Does rheumatic fever have an infectious or an immunological aetiology?
8 Why is migratory polyarthritis found in rheumatic heart disease?
9 Are penicillins still the drug of choice in streptococcal infections (particularly Strep. Pneumoniae)?
10 1. How long can the antistreptolysin-O (ASO) titre remain positive after a streptococcal infection? 2. What is the effect of a suitable antibiotic on the ASO titre, if any
Answer 1
There is no evidence that giving aciclovir during the primary infection
(chicken pox) has any effect on the subsequent development of
shingles.
Answer 2
To ensure safety for healthcare workers in this situation, antibody levels
should be checked 1-2 weeks post-vaccination.
Answer 3
No. Vancomycin-insensitive Staphylococcus aureus (VISA), vancomycinresistant Staphylococcus aureus (VRSA) and glycopeptide-resistant
enterococci (GRE) are also problems. Clostridium difficile is another
problem and occurs mainly after taking antibiotics.
Answer 4
Usually. Clostridium difficile is normally carried by approximately 5% of
the healthy population. It can cause diarrhoea after other normal bowel
commensals have been eliminated by antibiotics. In addition, debilitated
patients not on antibiotics can be infected by the faecal-oral route. Patients
and healthcare workers can spread the organism through hand contact,
hence the importance of hand washing.
Infectious diseases, tropical medicine and STI 4
21
Answer 5
Antibodies to streptococcal polysaccharides are substantially elevated
and can cross-react with some myocardial tissue antigens. The
pathogenesis is, however, far from clear.
Step-by-step explanation
Answer 6
Phenoxymethylpenicillin 250 mg twice daily until the age of 20 years or
for 5 years after the latest attack. This prevents recurrence and further
cardiac damage.
Answer 7
Both. Rheumatic fever starts with a streptococcal sore throat. It is
followed by an immunological response, which is the result of molecular
mimicry between the M proteins of the infecting Streptococcus pyogenes
and cardiac myosin and laminin. This causes the cardiac lesions. Also, see
next answer.
Answer 8
Migratory polyarthritis found in rheumatic fever is due to the reaction of
the circulating M protein of Streptococcus pyogenes and the synovial
membrane. It is therefore migratory. There is no long-term damage to the
joints.
Answer 9
Penicillin (usually amoxicillin) is the drug of choice for streptococcal
infections. However, resistance to Streptococcus pneumoniae is increasing
(up to 25% in some studies) and you should check your hospital's
antibiotic policy for the appropriate antibiotic.
Answer 10
1. The ASO titre peaks 4-5 weeks after infection. The levels then fall
rapidly with a slower decline after 6 months.
2. Antibiotics have no effect on the levels