Abstract
BackgroundGroup A streptococci (GAS) are known to cause serious invasive infections, but little is known about outcomes when patients with these infections are admitted to intensive care. We wanted to describe critically ill patients with severe sepsis or septic shock due to invasive GAS (iGAS) and compare them with other patients with severe sepsis or septic shock.MethodsAdult patients admitted to a general intensive care unit (ICU) in Sweden (2007–2019) were screened for severe sepsis or septic shock according to Sepsis 2 definition. Individuals with iGAS infection were identified. The outcome variables were mortality, days alive and free of vasopressors and invasive mechanical ventilation, maximum acute kidney injury score for creatinine, use of continuous renal replacement therapy and maximum Sequential Organ Failure Assessment score during the ICU stay. Age, Simplified Acute Physiology Score (SAPS 3) and iGAS were used as independent, explanatory variables in regression analysis. Cox regression was used for survival analyses.ResultsiGAS was identified in 53 of 1021 (5.2%) patients. Patients with iGAS presented a lower median SAPS 3 score (62 [56–72]) vs 71 [61–81]), p < 0.001), had a higher frequency of cardiovascular cause of admission to the ICU (38 [72%] vs 145 [15%], p < 0.001) and had a higher median creatinine score (173 [100–311] vs 133 [86–208] μmol/L, p < 0.019). Of the GAS isolates, 50% were serotyped emm1/T1 and this group showed signs of more pronounced circulatory and renal failure than patients with non-emm1/T1 (p = 0.036 and p = 0.007, respectively). After correction for severity of illness (SAPS 3) and age, iGAS infection was associated with lower mortality risk (95% confidence interval (CI) of hazard ratio (HR) 0.204–0.746, p < 0.001). Morbidity analyses demonstrated that iGAS patients were more likely to develop renal failure.ConclusionCritically ill patients with iGAS infection had a lower mortality risk but a higher degree of renal failure compared to similarly ill sepsis patients. emm1/T1 was found to be the most dominant serotype, and patients with emm1/T1 demonstrated more circulatory and renal failure than patients with other serotypes of iGAS.
Highlights
Group A streptococci (GAS) are known to cause serious invasive infections, but little is known about outcomes when patients with these infections are admitted to intensive care
53 patients (5.2%) were diagnosed with invasive GAS (iGAS) infection based on growth of the bacteria in blood or from other sterile sites
Patients with iGAS infection were less likely to be admitted from a general ward (21 [40] vs 527 [54], p = 0.047), and 15% arrived at the intensive care unit (ICU) from the operating room compared to 8% in the non-iGAS group (p = 0.074)
Summary
Group A streptococci (GAS) are known to cause serious invasive infections, but little is known about outcomes when patients with these infections are admitted to intensive care. Sepsis and the more severe form, septic shock, are devastating conditions with high mortality and morbidity caused by a systemic infection leading to organ dysfunction [1, 2]. A recent extensive systemic review of observational studies from North America and Europe showed that 10% of patients admitted to intensive care units (ICUs) were diagnosed with septic shock, with an ICU mortality of 38% [3]. One important gram-positive bacterium that causes sepsis is group A streptococcus (GAS), and it is remarkable how this very common bacterium, usually causing mild diseases such as pharyngitis and impetigo, can cause invasive infections that include necrotising fasciitis and streptococcal toxic shock syndrome (STSS). M proteins are virulence factors that contribute to the massive inflammatory effect seen in sepsis via stimulation of immune cells leading to extensive cytokine release [8]
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