Reference values of serum anti-streptolysin O in adults by nephelometry.

The anti-streptolysin O (ASO) test, which depends upon age and geographic location, is used to provide evidence for antecedent streptococcal infection in patients suspected of having rheumatic fever. Reference values of ASO have not previonsly been determined by nephelometric assay for laboratory use at Siriraj Hospital. A total of 402 serum specimens were collected from healthy adults aged between 16 and 63 years in Siriraj Hospital. They consisted of 235 blood donors, 150 subjects who were going to study aboard and 17 dentists. ASO concentrations from 5 groups according to five age ranges were compared and it was found that two age ranges which were 25 years old and younger and 26 years and older were appropriate to determine reference values. The reference values of ASO for these two age ranges, with 90% confidence intervals, were 486 (401-673) IU/ml and 385 (362-500) IU/ml, respectively.

Detection of congenital syphilis by using fluorescent treponemal antibody absorption test on fractionated sera (FTA-ABS 19s IgM).

The fluorescent treponemal antibody absorption test used with fractionated serum (FTA-ABS 19s IgM test) was evaluated as a test for congenital syphilis. From 1994 to 1995, 32 high-risk infants of mothers with untreated or inadequately treated syphilis and eight adults with primary or secondary syphilis were studied. The FTA-ABS 19s IgM was positive in 6 of 13 symptomatic babies (46 percent) with was a better rate than that given by the older method (38 percent), but only one adult gave a positive test (17 percent). This test was negative in all 50 controls studied, so the specificity was 100 percent. Although a negative FTA-ABS 19s IgM cannot be used to rule out congenital syphilis, a positive test should confirm suspected cases. The clinical features of congenital syphilis, as well as other laboratory investigations, re also discussed.