Secretory leucoprotease inhibitor (SLPI) is a neutrophil serine protease inhibitor constitutively expressed at many mucosal surfaces including that of the lung. Originally identified as a serine protease inhibitor, it is now evident that SLPI also has anti-microbial and anti-inflammatory functions, and therefore plays an important role in host defence. Previous work has shown that some host defence proteins such as SLPI and elafin are susceptible to proteolytic degradation. Consequently, we investigated the status of SLPI in the Cystic Fibrosis (CF) lung. A major factor that contributes to the high mortality rate among CF patients is Pseudomonas aeruginosa infection. In this study, we report that P. aeruginosa-positive CF bronchoalveolar lavage fluid (BALF), which contains lower SLPI levels and higher neutrophil elastase (NE) activity compared to P. aeruginosa-negative samples, was particularly effective at cleaving recombinant human SLPI. Additionally, we found that only NE inhibitors were able to prevent SLPI cleavage, thereby implicating NE in this process. NE in excess was found to cleave recombinant SLPI at two novel sites in the NH2-terminal region and abrogate its ability to bind LPS and NF-κB consensus binding sites but not its ability to inhibit activity of the serine protease cathepsin G. In conclusion, this study provides evidence that SLPI is cleaved and inactivated by NE present in P. aeruginosa-positive CF lung secretions and that P. aeruginosa infection contributes to inactivation of the host defence screen in the CF lung.

Background

There is growing interest in the potential utility of molecular diagnostics in improving the detection of life-threatening infection (sepsis). LightCycler® SeptiFast is a multipathogen probe-based real-time PCR system targeting DNA sequences of bacteria and fungi present in blood samples within a few hours. We report here the protocol of the first systematic review of published clinical diagnostic accuracy studies of this technology when compared with blood culture in the setting of suspected sepsis.

Methods/design

Data sources: the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects (DARE), the Health Technology Assessment Database (HTA), the NHS Economic Evaluation Database (NHSEED), The Cochrane Library, MEDLINE, EMBASE, ISI Web of Science, BIOSIS Previews, MEDION and the Aggressive Research Intelligence Facility Database (ARIF). Study selection: diagnostic accuracy studies that compare the real-time PCR technology with standard culture results performed on a patient's blood sample during the management of sepsis. Data extraction: three reviewers, working independently, will determine the level of evidence, methodological quality and a standard data set relating to demographics and diagnostic accuracy metrics for each study. Statistical analysis/data synthesis: heterogeneity of studies will be investigated using a coupled forest plot of sensitivity and specificity and a scatter plot in Receiver Operator Characteristic (ROC) space. Bivariate model method will be used to estimate summary sensitivity and specificity. The authors will investigate reporting biases using funnel plots based on effective sample size and regression tests of asymmetry. Subgroup analyses are planned for adults, children and infection setting (hospital vs community) if sufficient data are uncovered.

Dissemination

Recommendations will be made to the Department of Health (as part of an open-access HTA report) as to whether the real-time PCR technology has sufficient clinical diagnostic accuracy potential to move forward to efficacy testing during the provision of routine clinical care.

Registration

PROSPERO—NIHR Prospective Register of Systematic Reviews (CRD42011001289).

Article summary

Article focus

To describe the plans of a systematic review aimed at determining the diagnostic accuracy of a new real-time PCR technology (LightCycler® SeptiFast), designed to detect bloodborne pathogens in the setting of life-threatening infection (sepsis).

To highlight the unmet need for accurate and rapid infection diagnostics in the setting of life-threatening infection (sepsis).

Key messages

The study will provide the first independent systematic review of clinical validity studies of multiplex real-time PCR technology aimed at detecting circulating pathogen DNA straight from blood in the setting of suspected life-threatening infections (sepsis).

Based on the results of this study, independent recommendations will be made to the UK's Department of Health to help determine whether the real-time PCR technology has sufficient clinical diagnostic accuracy to move forward to efficacy testing during the provision of routine clinical care.

Strengths and limitations

The systematic review is focused on a single Conformité Européenne (CE)-marked real-time PCR technology designed for use in the setting of life-threatening infection (sepsis)

The systematic review is non-commercial and has been planned systematically by a multidisciplinary team of experts, working on behalf of the key stakeholders within a nationalised healthcare system.

Current clinical infection diagnostic reference standards may not have high diagnostic accuracy in all clinical settings and with all infections

Background

Human cathelicidin LL-37 is a cationic antimicrobial peptide (AMP) which possesses a variety of activities including the ability to neutralise endotoxin. In this study, we investigated the role of LPS neutralisation in mediating LL-37's ability to inhibit Pseudomonas aeruginosa LPS signalling in human monocytic cells.

Methodology/Principal Findings

Pre-treatment of monocytes with LL-37 significantly inhibited LPS-induced IL-8 production and the signalling pathway of associated transcription factors such as NF-κB. However, upon removal of LL-37 from the media prior to LPS stimulation, these inhibitory effects were abolished. These findings suggest that the ability of LL-37 to inhibit LPS signalling is largely dependent on extracellular LPS neutralisation. In addition, LL-37 potently inhibited cytokine production induced by LPS extracted from P. aeruginosa isolated from the lungs of cystic fibrosis (CF) patients. In the CF lung, polyanionic molecules such as glycosaminoglycans (GAGs) and DNA bind LL-37 and impact negatively on its antibacterial activity. In order to determine whether such interactions interfere with the LPS neutralising ability of LL-37, the status of LL-37 and its ability to bind LPS in CF sputum were investigated. Overall our findings suggest that in the CF lung, the ability of LL-37 to bind LPS and inhibit LPS-induced IL-8 production is attenuated as a result of binding to DNA and GAGs. However, LL-37 levels and its concomitant LPS-binding activity can be increased with a combination of DNase and GAG lyase (heparinase II) treatment.

Conclusions/Significance

Overall, these findings suggest that a deficiency in available LL-37 in the CF lung may contribute to greater LPS-induced inflammation during CF lung disease.

Acute lung injury (ALI) is a syndrome that is characterised by acute inflammation and tissue injury that affects normal gas exchange in the lungs. Hallmarks of ALI include dysfunction of the alveolar-capillary membrane resulting in increased vascular permeability, an influx of inflammatory cells into the lung and a local pro-coagulant state. Patients with ALI present with severe hypoxaemia and radiological evidence of bilateral pulmonary oedema. The syndrome has a mortality rate of approximately 35% and usually requires invasive mechanical ventilation. ALI can follow direct pulmonary insults, such as pneumonia, or occur indirectly as a result of blood-borne insults, commonly severe bacterial sepsis. Although animal models of ALI have been developed, none of them fully recapitulate the human disease. The differences between the human syndrome and the phenotype observed in animal models might, in part, explain why interventions that are successful in models have failed to translate into novel therapies. Improved animal models and the development of human in vivo and ex vivo models are therefore required. In this article, we consider the clinical features of ALI, discuss the limitations of current animal models and highlight how emerging human models of ALI might help to answer outstanding questions about this syndrome.

Introduction

Delirium in the intensive care unit (ICU) is associated with increased morbidity and mortality. Using an assessment tool has been shown to improve the ability of clinicians in the ICU to detect delirium. The confusion assessment method for the ICU (CAM-ICU) is a validated delirium-screening tool for critically ill intubated patients. The aim of this project was to establish the feasibility of routine delirium screening using the CAM-ICU and to identify the incidence of delirium in a UK critical care unit.

Methods

Routine CAM-ICU monitoring was implemented in a mixed critical care unit in January 2007 following a two-month educational and promotional campaign. Guidelines for the management of delirium were introduced. During a two-month prospective audit in September and October 2007, the daily CAM-ICU was recorded by the bedside nurse for consecutive level 2 and level 3 patients admitted to the mixed medical/surgical critical care ward in a district general hospital. This was repeated in January 2008. Patient outcome was recorded. The records of an additional cohort of ventilated patients were reviewed retrospectively to determine compliance with routine CAM-ICU assessments.

Results

Seventy-one patients were included in the observational cohort, with 60 patients in the retrospective cohort. In the prospective group it was not possible to assess for delirium with the CAM-ICU in nine patients due to persistent coma or inability to understand simple instructions. Excluding elective post-operative patients, the incidence of delirium was 45% in patients who could be assessed; in the 27 ventilated patients who could be assessed it was 63%. From the retrospective data compliance with the CAM-ICU assessment was 92%. The incidence of delirium in this retrospective group of ventilated patients who could be assessed was 65%.

Conclusions

We have demonstrated that delirium screening is feasible in a UK ICU population. The high incidence of delirium and the impact on outcomes in this UK cohort of patients is in line with previous reports.

Studies have indicated that measuring biochemical measures of epithelial injury in plasma and alveolar fluid may be useful in predicting outcome in acute lung injury. The present commentary briefly reviews the evidence supporting the use of these biochemical biomarkers of epithelial injury in acute lung injury, and in particular KL-6, as well as their limitations. The article additionally proposes the need for physiological markers of epithelial function to complement current biochemical biomarkers.

Introduction

The autopsy has long been regarded as an important tool for confirming the clinical cause of death, education and quality assurance. Concerns surrounding informed consent and the retention of organs have heightened clinicians' anxieties in requesting permission to perform an autopsy. The present study was conducted to determine whether the autopsy still has a role to play in extending knowledge about the cause of death in a group of patients who died while receiving intensive care.

Method

We retrospectively investigated trends in postmortem examination rates and discrepancies between premortem clinical and postmortem diagnoses in a population of critically ill patients admitted to a 13 bed, general medical/surgical intensive care unit between January 1998 and June 2001. Agreement between diagnoses before death and postmortem findings were compared using the Goldman system.

Results

Out of total 636 deaths, 49 (7.7%) underwent postmortem examinations. Of these, 38 (78%) cases were available for review. We found that postmortem findings were in complete agreement with predeath diagnoses in fewer than half of the cases (n = 17, 45%). Major missed diagnoses were present in 15 cases (39%). Myocardial infarction, carcinoma and pulmonary embolism represented the most frequently missed diagnoses.

Conclusion

Postmortem examinations remain a useful tool in confirming diagnostic accuracy and should be considered in all patients who die in the intensive care unit. Recognition of the diagnoses missed before death may improve outcome or avoid unnecessary prolongation of life where terminal disease is present.

Background

Pleotropic effects of statins on inflammation are hypothesised to attenuate the severity of and possibly prevent the occurrence of the host inflammatory response to pathogen and infection-related acute organ failure. We conducted an international survey of intensive care physicians in Australia, New Zealand (ANZ) and United Kingdom (UK). The aims of the survey were to assess the current prescribing practice patterns, attitudes towards prescribing statin therapy in critically ill patients and opinions on the need for an interventional trial of statin therapy in critically ill patients.

Methods

Survey questions were developed through an iterative process. An expert group reviewed the resulting 26 items for face and content validity and clarity. The questions were further refined following pilot testing by ICU physicians from Australia, Canada and the UK. We used the online Smart SurveyTM software to administer the survey.

Results

Of 239 respondents (62 from ANZ and 177 from UK) 58% worked in teaching hospitals; most (78.2%) practised in ‘closed’ units with a mixed medical and surgical case mix (71.0%). The most frequently prescribed statins were simvastatin (77.6%) in the UK and atorvastatin (66.1%) in ANZ. The main reasons cited to explain the choice of statin were preadmission prescription and pharmacy availability. Most respondents reported never starting statins to prevent (65.3%) or treat (89.1%) organ dysfunction. Only a minority (10%) disagreed with a statement that the risks of major side effects of statins when prescribed in critically ill patients were low. The majority (84.5%) of respondents strongly agreed that a clinical trial of statins for prevention is needed. More than half (56.5%) favoured rates of organ failure as the primary outcome for such a trial, while a minority (40.6%) favoured mortality.

Conclusions

Despite differences in type of statins prescribed, critical care physicians in the UK and ANZ reported similar prescription practices. Respondents from both communities agreed that a trial is needed to test whether statins can prevent the onset of new organ failure in patients with sepsis.

Background

Over the past ten years MRSA has become endemic in hospitals and is associated with increased healthcare costs. Critically ill patients are most at risk, in part because of the number of invasive therapies that they require in the intensive care unit (ICU). Washing with 5% tea tree oil (TTO) has been shown to be effective in removing MRSA on the skin. However, to date, no trials have evaluated the potential of TTO body wash to prevent MRSA colonization or infection. In addition, detecting MRSA by usual culture methods is slow. A faster method using a PCR assay has been developed in the laboratory, but requires evaluation in a large number of patients.

Methods/Design

This study protocol describes the design of a multicentre, phase II/III prospective open-label randomized controlled clinical trial to evaluate whether a concentration of 5% TTO is effective in preventing MRSA colonization in comparison with a standard body wash (Johnsons Baby Softwash) in the ICU. In addition we will evaluate the cost-effectiveness of TTO body wash and assess the effectiveness of the PCR assay in detecting MRSA in critically ill patients. On admission to intensive care, swabs from the nose and groin will be taken to screen for MRSA as per current practice. Patients will be randomly assigned to be washed with the standard body wash or TTO body wash. On discharge from the unit, swabs will be taken again to identify whether there is a difference in MRSA colonization between the two groups.

Discussion

If TTO body wash is found to be effective, widespread implementation of such a simple colonization prevention tool has the potential to impact on patient outcomes, healthcare resource use and patient confidence both nationally and internationally.

Trial Registration

[ISRCTN65190967]