Development and internal validation of clinical prediction models for outcomes of complicated intra-abdominal infection.

BACKGROUND: Complicated intra-abdominal infections (cIAIs) are associated with significant morbidity and mortality. The aim of this study was to describe the clinical characteristics of patients with cIAI in a multicentre study and to develop clinical prediction models (CPMs) to help identify patients at risk of mortality or relapse. METHODS: A multicentre observational study was conducted from August 2016 to February 2017 in the UK. Adult patients diagnosed with cIAI were included. Multivariable logistic regression was performed to develop CPMs for mortality and cIAI relapse. The c-statistic was used to test model discrimination. Model calibration was tested using calibration slopes and calibration in the large (CITL). The CPMs were then presented as point scoring systems and validated further. RESULTS: Overall, 417 patients from 31 surgical centres were included in the analysis. At 90 days after diagnosis, 17.3 per cent had a cIAI relapse and the mortality rate was 11.3 per cent. Predictors in the mortality model were age, cIAI aetiology, presence of a perforated viscus and source control procedure. Predictors of cIAI relapse included the presence of collections, outcome of initial management, and duration of antibiotic treatment. The c-statistic adjusted for model optimism was 0.79 (95 per cent c.i. 0.75 to 0.87) and 0.74 (0.73 to 0.85) for mortality and cIAI relapse CPMs. Adjusted calibration slopes were 0.88 (95 per cent c.i. 0.76 to 0.90) for the mortality model and 0.91 (0.88 to 0.94) for the relapse model; CITL was -0.19 (95 per cent c.i. -0.39 to -0.12) and - 0.01 (- 0.17 to -0.03) respectively. CONCLUSION: Relapse of infection and death after complicated intra-abdominal infections are common. Clinical prediction models were developed to identify patients at increased risk of relapse or death after treatment, these now require external validation.

Rapid in situ chondrocyte death induced by Staphylococcus aureus toxins in a bovine cartilage explant model of septic arthritis.

OBJECTIVE: To assess in situ chondrocyte viability following exposure to a laboratory strain and clinical isolates of Staphylococcus aureus. METHODS: Bovine cartilage explants were cultured in the presence of S. aureus 8325-4 (laboratory strain), clinical S. aureus isolates or non-infected culture medium of pH values 7.4, 6.4 and 5.4. All clinical isolates were isolated from the joint aspirates of patients presenting with S. aureus-induced septic arthritis (SA). At designated time points, in situ chondrocyte viability was assessed within defined regions-of-interest in the axial and coronal plane following live- and dead-cell image acquisition using the fluorescent probes 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI), respectively, and confocal laser-scanning microscopy (CLSM). Cartilage water content, following S. aureus 8325-4 exposure, was obtained by measuring cartilage wet and dry weights. RESULTS: S. aureus 8325-4 and clinical S. aureus isolates rapidly reduced in situ chondrocyte viability (>45% chondrocyte death at 40 h). The increased acidity, observed during bacterial culture, had a minimal effect on chondrocyte viability. Chondrocyte death commenced within the superficial zone (SZ) and rapidly progressed to the deep zone (DZ). Simultaneous exposure of SZ and DZ chondrocytes to S. aureus 8325-4 toxins found SZ chondrocytes to be more susceptible to the toxins than DZ chondrocytes. Cartilage water content was not significantly altered compared to non-infected controls. CONCLUSIONS: Toxins released by S. aureus have a rapid and fatal action on in situ chondrocytes in this experimental model of SA. These data advocate the prompt and thorough removal of bacteria and their toxins during the treatment of SA.

The Scottish enhanced Staphylococcus aureus bacteraemia surveillance programme: the first 18 months of data in children.

BACKGROUND: National enhanced surveillance of Staphylococcus aureus bacteraemia (SAB) commenced on 1st October 2014 to gain a more in-depth understanding of the epidemiology of SAB in Scotland. Children under 16 years of age were analysed separately from adults because previous studies had demonstrated epidemiological differences. AIM: To identify risk factors and patient populations at greatest risk to enable the development of focused improvement plans. METHODS: All National Health Service (NHS) boards within NHS Scotland take part in the mandatory enhanced surveillance, with data collected by trained data collectors using nationally agreed definitions. FINDINGS: Analysis of the first 18 months of data showed that hospital-acquired SAB was mostly associated with neonates with device risk factors, whereas community-associated SAB was found in older children who had few, if any, risk factors and most presented with a bone or joint infection. CONCLUSION: The enhanced SAB data highlighted the difference in risk factors and entry points for the acquisition of SAB within the paediatric population.

The Scottish enhanced Staphylococcus aureus bacteraemia surveillance programme: the first 18 months of data in adults.

BACKGROUND: Staphylococcus aureus bacteraemia (SAB) is the second most common source of positive blood cultures, after Escherichia coli, reported within NHS Scotland. Laboratory surveillance has been mandatory in Scotland for SAB since 2001. AIM: To gain an understanding of the epidemiology of SAB cases and associated risk factors for healthcare and true community onset. Identification of these factors and the patient populations at greatest risk enables the development of focused improvement plans. METHODS: All NHS boards within NHS Scotland take part in the mandatory enhanced surveillance, with data collected by trained data collectors using nationally agreed definitions. FINDINGS: Between 1st October 2014 and 31st March 2016, 2256 episodes of SAB in adults were identified. The blood cultures were taken in 58 hospitals and across all 15 Scottish health boards. The data demonstrated that approximately one-third of all SAB cases are true community cases. Vascular access devices continue to be the most reported entry point (25.7%) in individuals who receive health care, whereas skin and soft tissue risk factors are present in all origins. A significant risk factor unique to community cases is illicit drug injection. CONCLUSION: Improvement plans for reduction of SAB should be targeted more widely than hospital care settings alone.

[Microorganisms in clinical material collected from patients at the Public Clinical Hospital Nr 1 in Gdansk from 1997-1999]. / Drobnoustroje w próbkach materialów klinicznych od pacjentów Szpitala Klinicznego Nr 1 w Gdansku z lat 1997-1999.

Occurrence of microorganisms isolated from clinical specimens collected from patients in Clinical Hospital no. 1 in Gdansk in years 1997-1999 was analyzed. In this period there was no change in occurrence of Gram-negative bacteria, that accounted for 44-46% isolates. The number of isolations of Gram-positive bacteria dropped from 45% to 40%, and yeast risen from 5% to 10%. The analysis of blood cultures shows decrease in occurrence of bacteremia caused by Gram-negative bacteria and increase in occurrence bacteremia caused by Gram-positive bacteria and yeast. We observed also that the number of multi-resistant Gram-positive isolates (MRSA, VRE) decreased but there was rise in occurrence of multiresistant Gram-negative isolates (ESBL+, CRPA).