A comparison of paediatric and adult infectious diseases consultations in Australia and New Zealand

Advanced Imaging for Detection of Foci of Infection in Staphylococcus aureus Bacteremia- Can a Scan Save Lives?

Bloodstream infection or sepsis is a common cause of mortality globally. Staphylococcus aureus (S. aureus) is of particular concern, through its ability to seed metastatic infections in almost any organ after entering the bloodstream (S. aureus bacteraemia), often without localising signs. A positive blood culture for S. aureus bacteria should lead to immediate and urgent identification of the cause. Failure to detect a precise focus of infection is associated with higher mortality, sometimes despite appropriate antibiotics. This is likely due to the limited ability to effectively target therapy in occult lesions. Early detection of foci of metastatic S. aureus infection is therefore key for optimal diagnosis and subsequent therapeutic management. 18F-FDG-PET/CT and MRI offer us invaluable tools in the localisation of foci of S. aureus infection. Crucially, they may identify unexpected foci at previously unsuspected locations in the body, for example vertebral osteomyelitis in the absence of back pain. S. aureus bloodstream infections are further complicated by their microbiological recurrence; 18F-FDG-PET/CT provide a means of localising, thus enabling source control. More evidence is emerging as to the utility of 18F-FDG-PET/CT in this setting, perhaps even to the point of reducing mortality. 18 F-FDG-PET/MRI may have a similar impact. The available evidence demonstrates a need to investigate the impact of 18F-FDG-PET/CT and MRI scanning in clinical management and outcomes of S. aureus infection further in a randomised prospective clinical trial.

Pediatric Staphylococcus aureus bacteremia: clinical spectrum and predictors of poor outcome

BACKGROUND

Staphylococcus aureus is a common cause of bacteremia, yet the epidemiology, and predictors of poor outcome remain inadequately defined in childhood.

METHODS

ISAIAH is a prospective, cross-sectional study of S. aureus bacteremia (SAB), in children hospitalized in Australia and New Zealand, over 24-months (2017-2018).

RESULTS

Overall, 552 SABs were identified, (incidence 4.4/100,000/yr [95% confidence interval (CI) 2.2-8.8]), with methicillin-susceptible (84%), community onset (78%) infection predominating. Indigenous children (8.1/100,000/yr [CI 4.8-14.4]), those from lower-socioeconomic areas (5.5/100,000/yr [CI 2.8-10.2]) and neonates (6.6/100,000/yr (CI 3.4-11.7) were over-represented. Although 90-day mortality was infrequent, one-third experienced the composite of: length of stay >30 days (26%), ICU admission (20%), relapse (4%), or death (3%).Predictors of mortality included prematurity (aOR 16.8 [CI 1.6-296.9]), multifocal infection (aOR 22.6 [CI 1.4-498.5]), necrotizing pneumonia (aOR 38.9 [CI 1.7 - 1754.6]), multiorgan dysfunction (aOR 26.5 [CI 4.1-268.8]) and empiric-vancomycin (aOR 15.7 [CI 1.6-434.4]); whilst Infectious Diseases (ID) consultation (aOR 0.07 [CI 0.004-0.9]) was protective. Neither MRSA nor vancomycin trough-targets impacted survival; however, empiric-vancomycin was associated with significant nephrotoxicity (OR 3.1 [CI 1.3-8.1]).

CONCLUSIONS

High SAB incidence was demonstrated, with at-risk populations identified for future prioritized care. For the first time in a pediatric setting, necrotizing pneumonia and multifocal infection were predictors of mortality, whilst ID consultation was protective. The need to re-evaluate pediatric vancomycin trough-targets and limit unnecessary empiric-vancomycin exposure, to reduce poor outcomes and nephrotoxicity is highlighted. One in three children experienced considerable SAB morbidity, therefore pediatric inclusion in future SAB comparator trials is paramount to improve outcomes.

Infection characteristics and treatment of Staphylococcus aureus bacteraemia at a tertiary children's hospital

BACKGROUND

Staphylococcus aureus bacteraemia (SAB) causes considerable morbidity and mortality in children. Despite this, its epidemiology and risk factors are poorly understood, with minimal paediatric clinical trial data available to guide clinicians in management. We conducted a pilot study to characterise SAB and validate a severity classification for use in future clinical trials.

METHODS

Patients with SAB were prospectively identified at Princess Margaret Hospital for Children (Perth, Western Australia) from May 2011 to December 2013. Retrospective data were collected from clinical and laboratory records. Cases were classified based on a priori defined criteria as simple (single or contiguous, peripheral site focus) or complex (multi-site, deep tissue, no focus or sepsis) and tested against risk factors and markers of severity of infection.

RESULTS

There were 49 cases of SAB (median age 7.7 years), with classification as simple (n = 30, 61%) and complex (n = 19, 39%) respectively. There were no deaths or relapses in our cohort. Only 10% of isolates were methicillin resistant S. aureus (MRSA), and none of these were healthcare-associated. Age, gender, Indigenous status, MRSA and healthcare-associated infections were not predictive of complex infection. Pre-existing malignancy was a risk factor for complex infection (p = 0.02). Complex infections were associated with a higher median maximum C reactive protein (216 mg/L vs 50 mg/L, p = < 0.001), longer median length of stay (42 vs 10 days, p = < 0.001) and longer duration of antibiotic therapy (43 vs 34 days, p = 0.03).

DISCUSSION

This is the first attempt to categorise paediatric SAB as simple versus complex, to guide clinicians in decision making.

CONCLUSIONS

There is a wide spectrum of disease severity in paediatric SAB, with maximum CRP, length of stay, and duration of therapy greater in those with complex disease. Distinct cohorts with simple and complex courses which may be a target for future clinical trials have been described.