Age-related occurrence of inhibitory antibodies to streptococcal pyrogenic superantigens

Possible relationship between streptococcal pyrogenic exotoxin A and Kawasaki syndrome in patients older than six months of age

BACKGROUND

We previously investigated antibody titers against four kinds of superantigens [streptococcal pyrogenic exotoxin A (SPEA), streptococcal pyrogenic exotoxin C, toxic shock syndrome toxin-1 and staphylococcal enterotoxin B] in patients with Kawasaki syndrome (KS) younger than 6 months of age and reported a relationship between toxic shock syndrome toxin-1 and KS patients. In this study we have investigated antibody titers in KS patients older than 6 months of age.

METHODS

Serum of 81 patients with KS older than 6 months of age, before intravenous gamma-globulin therapy, and 88 normal age-matched children were used in this study. The IgG antibody titers against four kinds of superantigens were measured with an enzyme-linked immunosorbent assay.

RESULTS

The KS patients showed significantly elevated mean SPEA titer (P = 0.006) and significantly higher incidence of high SPEA (P = 0.0024) compared with the controls. The SPEA titer in KS patients showed a significant positive correlation with the number of days from onset of illness (P = 0.0002).

CONCLUSIONS

The elevated antibody titer against superantigens of KS patients older than 6 months of age was different from that of KS patients younger than 6 months of age. Our results suggest that KS patients' exposure to SPEA occurred a few weeks before the onset of KS. SPEA may be one of the possible etiologic agents of KS among patients older than 6 months of age in Kagoshima, Japan.

Improved outcome of clindamycin compared with beta-lactam antibiotic treatment for invasive Streptococcus pyogenes infection

CONTEXT

Animal model studies have demonstrated the failure of penicillin to cure Streptococcus pyogenes myositis and have suggested that clindamycin is a more effective treatment.

OBJECTIVE

To determine the most effective antibiotic treatment for invasive S. pyogenes infection in humans.

DESIGN AND SETTING

We conducted a retrospective review of the outcomes of all inpatients from 1983 to 1997 treated for invasive S. pyogenes infection at Children's Hospital.

PATIENTS

Fifty-six children were included, 37 with initially superficial disease and 19 with deep or multiple tissue infections.

MAIN OUTCOME MEASURE

Lack of progression of disease (or improvement) after at least 24 h of treatment.

RESULTS

The median number of antibiotic exposures was 3 per patient (range 1 to 6) with clindamycin predominating in 39 of 45 courses of protein synthesis-inhibiting antibiotics and beta-lactams predominating amongst the cell wall-inhibiting antibiotics in 123 of 126 of the remainder. Clindamycin was often used in combination with a beta-lactam antibiotic. Overall there was a 68% failure rate of cell wall-inhibiting antibiotics when used alone. Patients with deep infection were more likely to have a favorable outcome if initial treatment included a protein synthesis-inhibiting antibiotic as compared with exclusive treatment with cell wall-inhibiting antibiotics (83% vs. 14%, P = 0.006) with a similar trend in those with superficial disease (83% vs. 48%, P = 0.07). For those children initially treated with cell wall-inhibiting antibiotics alone, surgical drainage or debridement increased the probability of favorable outcome in patients with superficial disease (100% vs. 41%, P = 0.04) with a similar trend in a smaller number of deep infections (100% vs. 0%, P = 0.14).

CONCLUSIONS

This retrospective study suggests that clindamycin in combination with a beta-lactam antibiotic (with surgery if indicated) might be the most effective treatment for invasive S. pyogenes infection.

Toxic shock syndrome toxin-1 (TSST-1) antibody levels in burned children

Young children with burns are at risk of developing a toxic shock-like illness during the first 2-3 days after the injury. The staphylococcal exotoxin, toxic-shock syndrome toxin-1 (TSST-1) is implicated in development of this illness. Low levels or absence of anti-TSST-1 antibodies may indicate susceptibility to this illness. Anti-TSST-1 antibody levels were measured in consecutive cases admitted to the children's burns unit. Results of antibody levels in 38 of the youngest children, aged 0.04-4.0 years are reported. At the time of admission to the unit 50% of the children had IgG antibodies to TSST-1. A higher number of young burned children had antibodies to TSST-1 than expected.

Risk factors in the pathogenesis of invasive group A streptococcal infections: role of protective humoral immunity

An impressive change in the epidemiology and severity of invasive group A streptococcal infections occurred in the 1980s, and the incidence of streptococcal toxic shock syndrome cases continues to rise. The reason for the resurgence of severe invasive cases remains a mystery-has there been a change in the pathogen or in host protective immunity? To address these questions, we have studied 33 patients with invasive infection caused by genotypically indistinguishable M1T1 strains of Streptococcus pyogenes who had different disease outcomes. Patients were classified as having severe (n = 21) and nonsevere (n = 12) invasive infections based on the presence or absence of shock and organ failure. Levels of anti-M1 bactericidal antibodies and of anti-streptococcal superantigen neutralizing antibodies in plasma were significantly lower in both groups than in age- and geographically matched healthy controls (P < 0.01). Importantly, the levels of these protective antibodies in plasma samples from severe and nonsevere invasive cases were not different. Together the data suggest that low levels of protective antibodies may contribute to host susceptibility to invasive streptococcal infection but do not modulate disease outcome. Other immunogenetic factors that regulate superantigen responses may influence the severity of systemic manifestations associated with invasive streptococcal infection.