Rheumatic fever prophylaxis in South Africa--is bicillin 1,2 million units every 4 weeks appropriate?

Rheumatic fever is a major health problem in South Africa. Although intramuscular benzathine penicillin (bicillin) 1.2 million units (MU) every 4 weeks is widely used for secondary prophylaxis, studies in other countries have shown a recurrence rate of 3-8% over 5-6 years in patients on this regimen. It has been recommended that serum penicillin concentrations should be maintained above 0.02 mg/ml to prevent such recurrences. The World Health Organisation (WHO) and the American Heart Association have recommended since 1988 that patients in high-risk areas for the development of rheumatic fever should receive benzathine penicillin 1.2 MU every 3 weeks rather than every 4. The aims of this study were, firstly, to determine the prevalence of serum penicillin concentrations below 0.02 micrograms/ml in rheumatic fever patients on benzathine penicillin 1.2 MU 4-weekly and, secondly, to study the effect of increasing the dose of 1.8 MU 4-weekly in patients with subtherapeutic concentrations. Forty-five of 51 rheumatic fever patients (88%) in this study on benzathine penicillin 1.2 MU 4-weekly had low serum penicillin concentrations (< 0.02 micrograms/ml) at the end of the 4th week after the injection. Penicillin was detected in the urine of 30 of the 45 patients (67%) with low concentrations, suggesting that such patients have tissue-bound penicillin which might be important in preventing rheumatic fever. The 15 patients (33%) with subtherapeutic serum penicillin concentrations and no detectable penicillin in the urine could be at very high risk for recurrent attacks of rheumatic fever. Fourteen of 29 patients (48%) given the higher dose of benzathine penicillin (1.8 MU 4-weekly) had subtherapeutic serum penicillin concentrations at the end of the 4th week after the injection, but in all 29 penicillin was detected in the urine. Review of our present policy of secondary prophylaxis for rheumatic fever is necessary. Concentrated preparations of benzathine penicillin (600,000 U/ml) are not available in South Africa; administration of a higher dose (1.8 MU) 4-weekly would therefore require a double injection, which could affect compliance adversely. We recommend that rheumatic fever patients in our area should receive benzathine penicillin 1.2 MU 3-weekly as recommended by the WHO until strategies for secondary prophylaxis have been evaluated further.

Serum penicillin concentrations after intramuscular administration of benzathine penicillin G in children with rheumatic fever and controls.

Serum and urine penicillin levels were determined in 11 children with rheumatic fever (RF) who were receiving benzathine penicillin G (BPG) prophylactically every 3 weeks and in 10 children without RF who received the drug for the treatment of other infections. The dose given was 600,000 units for children weighing less than 25 kg and 1,200,000 units for those with a weight above 25 kg. Blood and urine samples were collected from both groups before and on days 7, 14 and 21 after BPG administration. Our results showed that: minimum inhibitory concentrations (MICs) of BPG for group A beta-hemolytic streptococci were 0.02 IU/ml or 0.0125 microgram/ml; intramuscular BPG did not give adequate serum levels to block the growth of group A beta-hemolytic streptococci in approximately 24 and 62% of children included in the study on days 14 and 21 after its administration, respectively; BPG metabolism was similar in both groups and did not depend on the underlying disease; serum and urine levels did not vary according to sex and weight; and there was a small correlation between serum and urine levels.

Survey of antibiotic residues in Canadian slaughter animals.

Kidneys and urine of cattle, swine, sheep and chickens were tested for bacterial growth inhibitors using Bacillus subtilis and Sarcina lutea as test organisms. Results were as follows: 211 beef kidneys four positive, 611 swine kidneys five positive, 27 sheep and 120 chicken kidneys all negative, 2108 beef urine 76 positive, 2409 swine urine 186 positive, 176 sheep urine 17 positive. Strongest reactions were obtained with B. subtilis on phosphate buffered pH 6.0 plates. Larger zones were produced by urine from injected animals than by tissue samples.