Toxic shock syndrome in a neonate

Characteristics of Invasive Staphylococcus aureus in United Kingdom Neonatal Units

BACKGROUND

In industrialized countries, Staphylococcus aureus (SA) is a leading cause of late-onset neonatal sepsis.

METHODS

Culture-proven episodes were identified prospectively from neonatal units participating in the neonatal infection surveillance network. Demographic, risk factor, and outcome data were collected.

RESULTS

Between 2004 and 2009, there were 117 episodes of SA infections (including 8 methicillin-resistant SA) in 116 infants from 13 units. The median gestational age and birth-weight were 27 weeks (90% ≤ 37 weeks, 85% ≤ 32 weeks) and 850 g (90% ≤ 2500 g), respectively. The overall incidence was 0.6 per 1000 live births and 23/1000 in infants <1500 g. Most episodes (94%) occurred more than 48 hours after birth (late onset). There were 7 early-onset episodes (< 48 hours) (median gestational age, 38.5 weeks), all due to methicillin-susceptible SA. At the time of culture, 67 of 95 (71%) infants were receiving respiratory support and 47 of 94 (50%) had a central line in situ. The majority of infants had nonspecific clinical features although evidence of focal infection (skin, soft tissue, bone, joint, or pneumonia) was ultimately seen in 41 of 91 (45%). There were 18 deaths, 4 (all late onset) directly due to methicillin-susceptible SA sepsis (4.4%).

CONCLUSIONS

SA is the second most common pathogen causing late-onset neonatal infections in this neonatal network. Infants who weigh < 1500 g in intensive care settings are the most vulnerable group. Clinical signs are not sufficiently distinctive to allow targeted therapy, suggesting that an antistaphylococcal agent should be part of empiric therapy for late-onset sepsis in premature infants.

Inhibition of toxic shock by human monoclonal antibodies against staphylococcal enterotoxin B

Background

Staphylococcus aureus is implicated in many opportunistic bacterial infections around the world. Rising antibiotic resistance and few alternative methods of treatment are just two looming problems associated with clinical management of S. aureus. Among numerous virulence factors produced by S. aureus, staphylococcal enterotoxin (SE) B is a secreted protein that binds T-cell receptor and major histocompatibility complex class II, potentially causing toxic shock mediated by pathological activation of T cells. Recombinant monoclonal antibodies that target SEB and block receptor interactions can be of therapeutic value.

Methodology/Principal Findings

The inhibitory and biophysical properties of ten human monoclonal antibodies, isolated from a recombinant library by panning against SEB vaccine (STEBVax), were examined as bivalent Fabs and native full-length IgG (Mab). The best performing Fabs had binding affinities equal to polyclonal IgG, low nanomolar IC₅₀s against SEB in cell culture assays, and protected mice from SEB-induced toxic shock. The orthologous staphylococcal proteins, SEC1 and SEC2, as well as streptococcal pyrogenic exotoxin C were recognized by several Fabs. Four Fabs against SEB, with the lowest IC₅₀s, were converted into native full-length Mabs. Although SEB-binding kinetics were identical between each Fab and respective Mab, a 250-fold greater inhibition of SEB-induced T-cell activation was observed with two Mabs.

Conclusions/Significance

Results suggest that these human monoclonal antibodies possess high affinity, target specificity, and toxin neutralization qualities essential for any therapeutic agent.

Intravenous immunoglobulin in children with streptococcal toxic shock syndrome

BACKGROUND

Streptococcal toxic shock syndrome (TSS) is a rare and severe manifestation of group A streptococcal infection. The role of intravenous immunoglobulin (IVIG) for streptococcal TSS in children is controversial. This study aims to describe the epidemiology of streptococcal TSS in children and to determine whether adjunctive therapy with IVIG is associated with improved outcomes.

METHODS

A multicenter, retrospective cohort study of children with streptococcal TSS from 1 January 2003 through 31 December 2007 was conducted. Propensity scores were used to determine each child's likelihood of receiving IVIG. Differences in the primary outcomes of death, hospital length of stay, and total hospital costs were compared after matching IVIG recipients and nonrecipients on propensity score.

RESULTS

The median patient age was 8.2 years. IVIG was administered to 84 (44%) of 192 patients. The overall mortality rate was 4.2% (95% confidence interval, 1.8%-8.0%). Differences in mortality between IVIG recipients (n = 3; 4.5%) and nonrecipients (n = 3; 4.5%) were not statistically significant (p > .99). Although patients receiving IVIG had higher total hospital and drug costs than nonrecipients, differences in hospital costs were not significant once drug costs were removed (median difference between matched patients, $6139; interquartile range, -$8316 to $25,993; P = .06). No differences were found in length of hospital stay between matched IVIG recipients and nonrecipients.

CONCLUSION

This multicenter study is, to our knowledge, the largest to describe the epidemiology and outcomes of children with streptococcal TSS and the first to explore the association between IVIG use and clinical outcomes. IVIG use was associated with increased costs of caring for children with streptococcal TSS but was not associated with improved outcomes.