New normal ranges of antistreptolysin O and antideoxyribonuclease B titres for Australian children

Revising the value of Antistreptolysin O titre in childhood and its interpretation in the diagnostic approach of rheumatic diseases

The burden of group A streptococcus (GAS) infection and its rheumatic sequelae remains dramatically high, especially in low-income countries. Recently, an increased number of Acute Rheumatic Fever (ARF) cases was documented in many regions of Italy. The diagnosis of rheumatic sequelae relies on clinical signs and on the evaluation of the Antistreptolysin O titre (ASO), whose variations are globally reported. To re-examine the standard reference value of ASO titre, by measuring either its upper limit of normal (ULN) in a population of healthy children (HC) or comparing these values with streptococcal antibodies registered in a cohort of patients affected by the rheumatic sequelae of GAS infection. We performed a multicenter retrospective study. We enrolled 125 HC, aged 2-17 years, and a total of 181 patients affected by ARF, acute streptococcal pharyngitis, post-streptococcal arthritis, Henoch-Schönlein purpura and erythema nodosum, divided into four groups. The levels of ASO and anti-deoxyribonuclease B (anti-DNase B) titres were analyzed and compared among the various groups. Moreover, the 80th percentile value was calculated and established as the ULN for ASO titre in HC group. The ULN for ASO titre in overall HC group was 515 IU/mL, resulting in higher than used in the routine investigation. The ASO titre was significantly higher in patients with rheumatic sequelae compared with HC group, with a peak in the age between 5 and 15 years.    Conclusion: Our study established a new ULN normal value of streptococcal serology in a childhood and adolescent population of Italy, suggesting the need to extend this revaluation to the critical areas, in order to avoid underestimating ARF diagnosis. The correct interpretation of ASO and anti-DNase B values in the context of rheumatic diseases has been discussed. What is Known: • The global burden of disease caused by group A streptococcus is not known and remains an important cause of morbidity and mortality. Acute rheumatic fever continues to be a serious worldwide public health problem and a recent recurrence of group A streptococcus infection cases is observed. • The streptococcal sequelae requires evidence of preceding streptococcal infection, commonly elevated streptococcal antibody titre, but the upper limit for these titres varies considerably based on age group, region, and origin. What is New: • This study provides population-specific values for streptococcal antibody titres in Italy. • Interpret the results of group A streptococcal antibody tests within the clinical context.

Study of streptococcal antibody (anti-streptolysin O) among healthy children in Bangladesh

Objectives:

The standard reference value of anti-streptolysin O (ASO) titre for diagnosing acute rheumatic fever (RF) in children is yet to be determined in Bangladesh. We aimed to measure the upper limit of the normal (ULN) of ASO titre among healthy children to determine the cut-off value for the diagnosis of RF in Bangladesh.

Methods:

A total of 400 healthy children aged 5–15 years with no history of fever, sore throat and impetigo during the last 8 weeks of the study were enrolled. The respondents were randomly selected from an urban non-slum area, an urban slum area and a rural area of Bangladesh. ASO titre was measured using a turbidimetric immunoassay based on the principle of an agglutination reaction. The 80th percentile value was considered as the ULN of ASO titre.

Results:

Approximately 55% of the children were male. The mean (SD) age of children was 9.1 (2.7) years. The ULN of ASO titre for 5–15 years aged children was 217.4 IU/mL.

Conclusion:

Our reference value of ASO titre at the 80th percentile will be an essential guide for clinicians to diagnose acute RF.

Normal values of antistreptolysin O for adults ages 30 to 70 in Syria: A cross sectional study

Background

Group A Streptococcus is a very common pathogen which infects a large scale of people around the world causing many symptoms such as scarlet fever, sinusitis, and pneumonia. Most strains of group A and many other strains of group C and G Streptococcus bacteria secreted antigen called Streptolysin O. Anti-streptolysin O (ASO) is an antibody produced against streptolysin O that rises after 1 week of infection by streptococcus bacteria, which helps in diagnosing this type of infectious diseases. We conducted a Cross-Sectional study to determine the Upper Limit of Normal (ULN) for healthy adult in Aleppo, Syria.

Materials and methods

A sero-epidemiological cross-sectional study was conducted from September to October in 2019. ASO titers were determined on 267 healthy patients’ companions who visited Aleppo University Hospital. Geometric mean titer and Upper Limit of Normal of ASO were calculated according to sex, age and residency. Upper Limit of Normal were defined as the 80th percentile.

Results

Out of 267 participants; 126 (45.7%) were males and 150 (54.3) were females. The Upper Limit of Normal for total participants was 210.8 IU/ml. There was no significant difference (P-value > 0.05) among males (204.6 IU/ml) and females (225.8 IU/ml). In contrast to sex, there was a significant difference (P-value < 0.05) according to age groups, where the highest Upper Limit of Normal was in the 30–39 age group (256.0 IU/ml).

Conclusion

ASO test is a common, easy, cheap method, so getting enough data about it is very important in the developing countries (such as Syria). In Aleppo, Syria we found that the ULN was higher than ULN from other studies. There was no significant difference according to sex and residency. On the other hand, there was significant difference according to age groups.

•

The Upper Limit of Normal for total participants was 210.8 IU/ml.

•

We found that the ULN was higher than ULN from other studies.

•

There was significant difference in ULN according to age groups.

Cross-sectional study of population-specific streptococcal antibody titres in Uganda

OBJECTIVE

Despite substantial variation of streptococcal antibody titres among global populations, there is no data on normal values in sub-Saharan Africa. The objective of this study was to establish normal values for antistreptolysin O (ASO) and antideoxyribonuclease B (ADB) antibodies in Uganda.

DESIGN

This was an observational cross-sectional study.

SETTING

This study was conducted at Mulago National Referral Hospital, which is located in the capital city, Kampala, and includes the Uganda Heart Institute.

PATIENTS

Participants (aged 0-50 years) were recruited. Of 428 participants, 22 were excluded from analysis, and 183 (44.4%) of the remaining were children aged 5-15 years.

MAIN OUTCOME MEASURES

ASO was measured in-country by nephelometric technique. ADB samples were sent to Australia (PathWest) for analysis by enzyme inhibition assay: 80% upper limit values were established.

RESULTS

The median ASO titre in this age group was 220 IU/mL, with the 80th percentile value of 389 IU/mL. The median ADB titre in this age group was 375 IU/mL, with the 80th percentile value of 568 IU/mL.

CONCLUSIONS

The estimated Ugandan paediatric population standardised 80% upper-limit-of-normal ASO and ADB titres is higher than many global populations. Appropriateness of using population-specific antibody cutoffs is yet to be determined and has important implications for the sensitivity and specificity of rheumatic fever diagnosis.

Development and Evaluation of a New Triplex Immunoassay That Detects Group A Streptococcus Antibodies for the Diagnosis of Rheumatic Fever

Streptococcal serology is a cornerstone in the diagnosis of acute rheumatic fever (ARF), a postinfectious sequela associated with group A Streptococcus infection. Current tests that measure anti-streptolysin O (ASO) and anti-DNaseB (ADB) titers require parallel processing, with their predictive value limited by the low rate of decay in antibody response. Accordingly, our objective was to develop and assess the diagnostic potential of a triplex bead-based assay, which simultaneously quantifies ASO and ADB together with titers for a third antigen, SpnA. Our previous cytometric bead assay was transferred to the clinically appropriate Luminex platform by coupling streptolysin O, DNaseB, and SpnA to spectrally unique magnetic beads. Sera from more than 350 subjects, including 97 ARF patients, were used to validate the assay and explore immunokinetics. Operating parameters demonstrate that the triplex assay produces accurate and reproducible antibody titers which, for ASO and ADB, are highly correlative with existing assay methodology. When ARF patients were stratified by time (days following hospital admission), there was no difference in ASO and ADB between <28 and 28+ day groups. However, for anti-SpnA, there was a significant decrease (P < 0.05) in the 28+ day group, indicative of faster anti-SpnA antibody decay. Anti-SpnA immunokinetics support very recent group A Streptococcus infection and may assist in diagnostic classification of ARF. Further, bead-based assays enable streptococcal serology to be performed efficiently in a high-throughput manner.

Comparison of antistreptolysin O and anti-deoxyribonucleic B titers in healthy children to those with acute pharyngitis, acute rheumatic fever, and rheumatic heart disease aged 5-15 years

BACKGROUND

Acute rheumatic fever (ARF) affects millions of children in the third world countries like India. The diagnosis of rheumatic fever is based on the Jones criteria with serological titers, antistreptolysin O titer (ASO), and anti-deoxyribonucleic B (ADB), taken as evidence of recent streptococci infection. There is a lack of recent data available on ASO and ADB titers in children from the Delhi/NCR and thus adequate geographical area-specific cutoffs for the region are not available.

AIMS AND OBJECTIVES

The aim of this study is to determine and compare the ASO and ADB antibody titers in children with acute pharyngitis, ARF, rheumatic heart disease (RHD), and in healthy children of the Delhi/NCR region.

MATERIALS AND METHODS

Twenty-six cases of ARF, 51 cases of RHD, 50 cases of acute pharyngitis, and 84 healthy normal children were included in the study. A single ASO and ADB titer measurement was done in these children.

RESULTS

The ASO titers was raised in acute pharyngitis - 303 IU/ml (interquartile range [IQR], 142-520 IU/ml) and ARF - 347.5 IU/ml (IQR, 125-686 IU/ml) children in comparison to healthy controls - 163.5 IU/ml (IQR, 133-246.5 IU/ml) and RHD patients - 163 IU/ml (IQR, 98.250-324.500). The ADB titers were highest in ARF patients - 570.5 IU/ml (IQR, 276-922 IU/ml) followed with RHD - 205 IU/ml (IQR, 113.6-456.5), healthy controls - 78.25 IU/ml (IQR, 53.39-128.15 IU/ml), and acute pharyngitis - 75.12 IU/ml (IQR, 64.5-136 IU/ml). The upper limit of normal (ULN) values of ASO and ADB computed from normal healthy children were 262.4 IU/ml and 134.44 IU/ml, respectively, and these can be used as cutoff values for recent streptococcal infection in this geographical area.

CONCLUSIONS

The median ASO titers in acute pharyngitis group and ARF were significantly raised compared to that of the control group. The ADB titers were raised in ARF and RHD patients albeit the levels were higher in ARF patients. The derived ULN values can be used as cutoff reference.

Streptococcal Serology in Acute Rheumatic Fever Patients: Findings From 2 High-income, High-burden Settings

BACKGROUND

Globally, there is wide variation in streptococcal titer upper limits of normal (ULN) for antistreptolysin O (ASO) and anti-deoxyribonuclease B (ADB) used as an evidence of recent group A streptococcal infection to diagnose acute rheumatic fever (ARF).

METHODS

We audited ASO and ADB titers among individuals with ARF in New Zealand (NZ) and in Australia's Northern Territory. We summarized streptococcal titers by different ARF clinical manifestations, assessed application of locally recommended serology guidelines where NZ uses high ULN cut-offs and calculated the proportion of cases fulfilling alternative serologic diagnostic criteria.

RESULTS

From January 2013 to December 2015, group A streptococcal serology results were available for 350 patients diagnosed with ARF in NZ and 182 patients in Northern Territory. Median peak streptococcal titers were similar in both settings. Among NZ cases, 267/350 (76.3%) met NZ serologic diagnostic criteria, whereas 329/350 (94.0%) met Australian criteria. By applying Australian ULN titer cut-off criteria to NZ cases, excluding chorea, ARF definite cases would increase by 17.6% representing 47 cases.

CONCLUSIONS

ASO and ADB values were similar in these settings. Use of high ULN cut-offs potentially undercounts definite and probable ARF diagnoses. We recommend NZ and other high-burden settings to use globally accepted, age-specific, lower serologic cut-offs to avoid misclassification of ARF.

The novel Group A Streptococcus antigen SpnA combined with bead-based immunoassay technology improves streptococcal serology for the diagnosis of acute rheumatic fever

OBJECTIVES

Streptococcal serology provides evidence of prior Group A Streptococcus (GAS) exposure, crucial to the diagnosis of acute rheumatic fever (ARF) and post-streptococcal glomerulonephritis. However, current tests, which measure anti-streptolysin-O and anti-DNaseB antibodies, are limited by false positives in GAS endemic settings, and incompatible methodology requiring the two tests to be run in parallel. The objective was to improve streptococcal serology by combining the novel GAS antigen, SpnA, with streptolysin-O and DNaseB in a contemporary, bead-based immunoassay.

METHODS

Recombinant streptolysin-O, DNAseB and SpnA were conjugated to polystyrene beads with unique fluorescence positions so antibody binding to all three antigens could be detected simultaneously by cytometric bead array. Multiplex assays were run on sera collected in three groups: ARF; ethnically matched healthy children; and healthy adults.

RESULTS

The ability of the antigens to detect a previous GAS exposure in ARF was assessed using the 80th centile of the healthy children group as cut-off (upper limit of normal). SpnA had the highest sensitivity at 88%, compared with 75% for streptolysin-O and 56% for DNaseB.

CONCLUSIONS

SpnA has favorable immunokinetics for streptococcal serology, and can be combined with anti-streptolysin-O and anti-DNaseB in a multiplex format to improve efficiency and accuracy.

Evaluation of the American Heart Association 2015 revised Jones criteria versus existing guidelines

OBJECTIVES

To compare the diagnostic yield of acute rheumatic fever (ARF) by the American Heart Association/ American College of Cardiology (AHA/ACC) 2015 revised Jones criteria with the WHO 2004 and Australian guidelines 2012.

METHODS

Retrospective observational study in 93 cases of suspected ARF admitted to the Division of Paediatric Cardiology between January 2012 and December 2014. WHO 2004, Australian guidelines and AHA/ACC 2015 Jones criteria were applied to assess definite and probable ARF.

RESULTS

Of the 93 cases, 50 were diagnosed as the first episode of ARF and 43 as a recurrence of the condition. Subclinical carditis was a predominant presentation (38%) in the first episode group (p<0.01) whereas in the recurrence group carditis (88%) was the main presentation (p<0.01). Among the joint manifestations, the majority of patients in both the first episode group and the recurrence group presented with arthralgia. Of all the patients with suspected ARF (50), 34% of cases did not fulfil the standard Jones criteria 2004; however, 86% qualified as having ARF on applying the Australian and AHA/ACC 2015 criteria. Surprisingly in the recurrence group only 67% of the patients fulfilled AHA/ACC 2015 despite the modifications incorporated beyond WHO 2004; however, all the patients fulfilled the Australian guidelines either as definite (88.4%) or probable (11.6%). Inclusion of subclinical carditis, polyarthralgia and monoarthritis as major criteria influenced the diagnosis to definite ARF in 20%, 10% and 4% of patients, respectively.

CONCLUSIONS

The clinical manifestations of ARF, comprising subclinical carditis and arthralgia, are possibly milder in the Indian population; hence, inclusion of subclinical carditis, polyarthralgia and monoarthritis as major criteria in the newer guidelines has improved the diagnostic yield of ARF. In the absence of a gold standard for the diagnosis of ARF, it is not possible to comment on sensitivity and specificity.

How to use antistreptolysin O titre

Group A streptococcus (GAS) is the cause of a wide range of acute suppurative and, following a latent period, non-suppurative diseases such as rheumatic fever and poststreptococcal glomerulonephritis. Diagnosis of the latter group requires evidence of preceding GAS infection. The bacteria produce a range of extracellular antigens, including streptolysin O, which induce an antibody response in the host. A rise in antistreptolysin O titre (ASOT) is indicative of preceding GAS infection. In clinical practice, often only a single ASOT measurement is available and its timing in relation to a possible GAS infection is unknown. Interpretation of the result in this context is liable to misdiagnosis. In order to optimise diagnosis of preceding GAS infection, at least two sequential ASOT measurements, together with simultaneous assay for anti-DNase B, a second antistreptococcal antibody, is recommended.

Maternal β-hemolytic streptococcal pharyngeal exposure and colonization in pregnancy

Objectives. To report the pharyngeal colonization rate of β-hemolytic streptococci and changes in the value of antistreptolysin O (ASO) and anti-DNase B serology titers during pregnancy. Methods. Healthy pregnant women were recruited and blood was drawn in each trimester. The upper limit of normal (ULN) values for ASO and anti-DNase B was calculated for each trimester. Throat swabs were collected for culture and positive cultures were further assessed for the identification of serogroup of the isolated β-hemolytic streptococcus. Results. Out of a total of 126 pregnant women, 34.1% had positive throat cultures. Group C and group G strains were isolated in 18.2% of throat cultures while group F was detected in 13.5% of cases. The rate of colonization with GAS was 1.6%. There was an overall drop in ASO titer during pregnancy while anti-DNase B titers remained relatively unchanged. ULN values of 164^IU, 157^IU, and 156^IU were calculated for ASO at the first, second, and third trimesters, respectively. Based on the ULN values, 28.6% of patients had recent streptococcal exposure. Conclusions. These results show that pregnant women act as a reservoir for spreading potentially immunogenic (groups C and G) and disease producing (group F) virulent strains of streptococci.

Clinical significance of pleural effusion in the new influenza A (H1N1) viral pneumonia in children and adolescent

BACKGROUND

Parapneumonic effusion has been reported to develop either in typical bacterial infection or in viral pneumonia with bacterial co-infection and to cause death. Swine-origin influenza A (H1N1) virus infection can be accompanied with pleural effusion; however, there are no reports about the significance of pleural effusion in H1N1 pneumonia. We retrospectively analyzed both the clinical characteristics and the significance of pleural effusion associated with H1N1 pneumonia in children and adolescent.

METHOD

Eighty-nine patients who were admitted with H1N1 pneumonia were divided into two groups: 17 patients with pleural effusion (i.e., the effusion group), and 72 patients without pleural effusion (the non-effusion group).

RESULTS

Lymphopenia (P = 0.030), elevation of the C-reactive protein (P = 0.026), and positive rate of anti-sptreptolysin O titer (P = 0.040) were significantly increased in the effusion group than in the non-effusion group. In addition, the need for treatment with both oxygen (P < 0.001) and oseltamivir (P = 0.013) was significantly increased in the effusion group. However, there was no significant difference between the two investigated groups in the duration of the treatment with intravenous antibiotics, the time of fever remission calculated from admission, and the days of hospital stay. Also, there was no documented bacterial co-infection in any of the studied groups.

CONCLUSION

This result suggested that pleural effusion in H1N1 pneumonia could develop without bacterial co-infection and had mild clinical course.

Antistreptolysin O titer in health and disease: levels and significance

Over diagnosis of acute rheumatic fever (ARF) based on a raised antistreptolysin O titer (ASOT) is not uncommon in endemic areas. In this study, 660 children (aged 9.2 ±1.7 years) were recruited consecutively and classified as: G1 (control group, n=200 healthy children), G2 (n=20 with ARF 1(st) attack), G3 (n=40 with recurrent ARF), G4 (n=100 with rheumatic heart disease (RHD) on long acting penicillin (LAP)), G5 (n=100 with acute follicular tonsillitis), and G6 (n=200 healthy children with history of repeated follicular tonsillitis more than three times a year). Serum ASOT was measured by latex agglutination. Upper limit of normal (ULN) ASOT (80(th) percentile) was 400 IU in G1, 200 IU in G4, and 1600 IU in G6. Significantly high levels were seen in ARF 1st attack when compared to groups 1 and 5 (P<0.001 and P<0.05, respectively). ASOT was significantly high in children over ten years of age, during winter and in those with acute rheumatic carditis. ASOT showed significant direct correlation with the number of attacks of tonsillitis (P<0.05). Egyptian children have high ULN ASOT reaching 400 IU. This has to be taken into consideration when interpreting its values in suspected ARF. A rise in ASOT is less prominent in recurrent ARF compared to 1st attack, and acute and recurrent tonsillitis. Basal levels of ASOT increase with age but the pattern of increase during infection is not age dependent.

A preliminary study of the frequency of anti-basal ganglia antibodies and streptococcal infection in attention deficit/hyperactivity disorder

Attention deficit/hyperactivity disorder (ADHD) is often present in patients with post-streptococcal neuropsychiatric disorders such as Sydenham's chorea and PANDAS, in which anti-basal ganglia antibodies (ABGA) have been frequently found. Our study investigates the hypothesis that pharyngeal group A beta-hemolytic streptococcus (GABHS) infections and serum ABGA are more frequent in children with ADHD non-comorbid (nc-ADHD) with obsessive-compulsive disorder or tics than in controls. We compared 22 children with nc-ADHD (DSM-IV-TR) and 22 healthy controls matched by age, gender and season of sample collection, for the frequency of recent GABHS infection and the presence of ABGA. Eleven out of 22 children (51%) with nc-ADHD showed evidence of GABHS infection compared to three out of 22 (14%) controls (P = 0.007). We found positive ABGA in one ADHD subject (4%) and in one control (4%). This preliminary study indicates that frequency of ABGA in children with nc-ADHD does not differ from that in matched controls, despite the fact that our ADHD patients had had more recent GABHS infections than the controls. This suggests that ABGA do not have a role in the pathogenesis of nc-ADHD.

Normal ranges of streptococcal antibody titers are similar whether streptococci are endemic to the setting or not

Group A streptococcal (GAS) serology is used for the diagnosis of post-streptococcal diseases, such as acute rheumatic fever, and occasionally for the diagnosis of streptococcal pharyngitis. Experts recommend that the upper limits of normal for streptococcal serology be determined for individual populations because of differences in the epidemiology of GAS between populations. Therefore, we performed a study to determine the values of the upper limit of normal for anti-streptolysin O (ASO) and anti-DNase B (ADB) titers in Fiji. Participants with a history of GAS disease, including pharyngitis or impetigo, were excluded. A total of 424 serum samples from people of all ages (with a sample enriched for school-aged children) were tested for their ASO and ADB titers. Reference values, including titers that were 80% of the upper limit of normal, were obtained by regression analysis by use of a curve-fitting method instead of the traditional nonparametric approach. Normal values for both the ASO titer and the ADB titer rose sharply during early childhood and then declined gradually with age. The estimated titers that were 80% of the upper limit or normal at age 10 years were 276 IU/ml for ASO and 499 IU/ml for ADB. Data from our study are similar to those found in countries with temperate climates, suggesting that a uniform upper limit of normal for streptococcal serology may be able to be applied globally.

Burden of acute sore throat and group A streptococcal pharyngitis in school-aged children and their families in Australia

OBJECTIVE

The objective of this study was to determine the incidence, transmission, carriage, and risk factors for group A streptococcal pharyngitis in school-aged children and their families.

METHODS

A 16-month, prospective, family-based cohort study was undertaken from August 2001 through December 2002 in Melbourne, Australia. A total of 202 families (853 people) with at least 1 child aged 3 to 12 years were randomly selected from 3 primary care practices across suburban Melbourne to collect surveillance data for acute group A streptococcal pharyngitis, including serology for index and secondary cases and intermittent carriage data. Cohort retention was 97% for 16 months.

RESULTS

The incidence of acute sore throat, group A streptococcal swab-positive pharyngitis, and serologically confirmed group A streptococcal pharyngitis was 33, 13, and 8 per 100 child-years, respectively, for school-aged children (5-12 years) and 60, 20, and 15 per 100 family-years, respectively. Sore throat was less common in adults than children, but adults with sore throat were as likely as children to have group A streptococcal culture-positive or serologically proven pharyngitis. In families who had a primary case, 43% had at least 1 secondary case, and in family members who were at risk, 13% contracted a secondary case. The spring, summer, and winter carriage rates for children were 13%, 8%, and 16%, respectively, and for adults the rate was 2% across all seasons.

CONCLUSIONS

Group A streptococcal pharyngitis is still common, and the peak incidence occurs in school-aged children. However, the incidence in adults is higher than expected, and the number of secondary cases in families may be an important factor when considering the potential benefits of treatment.