In situ diagnostic methods for catheter related bloodstream infection in burns patients: A pilot study.

BACKGROUND: One of the most common and potentially fatal complications in critically ill burns patients is catheter related bloodstream infection (CR-BSI). Lack of in situ diagnostic techniques requires device removal if CR-BSI is suspected with 75-85% of catheters withdrawn unnecessarily. AIMS: To assess the sensitivity, specificity and accuracy of two in situ diagnostic methods for CR-BSI in an adult ICU burns population: Differential Time to Positivity (DTP) and Semi-Quantitative Superficial Cultures (SQSC). METHODS: Both arterial (AC) and central venous (CVC) catheters were studied. On clinicians' suspicion of CR-BSI, the CVC and AC were removed. Superficial semi-quantitative cultures were taken by removing the dressings and swabbing within a 3cm radius of the CVC and AC insertion sites, as well as inside each hub of the CVC and AC. Peripheral blood was taken for qualitative culture and the catheter tip sent for semi-quantitative culture. DTP was considered positive if culture of lumen blood became positive at least 120min before peripheral blood with an identical pathogen. Superficial and tip cultures were identified as positive if ≥15 CFUs were grown. CR-BSI was confirmed when both catheter tip culture and peripheral blood culture were positive with the same micro-organism. RESULTS: Sixteen patients (88% male) with an APACHE II score of 22.0 (7.3) were enrolled. The mean age was 45.7 (16.9) years with mean total burn surface area 32.9 (19.4)%. Fifty percent had airway burns. ICU stay was 19.9 (11.1) days. All 16 survived ICU discharge with a hospital survival of 93%. There were 20 episodes of CR-BSI in these 16 patients. For these 20 episodes the exposure time (line days) was 113.15. The CR-BSI rate was 15.6 per 1000 catheter days (95% CI 1.9-56.4). For diagnosis of CR-BSI in either AC and CVC, SQSC had a sensitivity of 50% [95% CI 3-97], specificity 83.3% [95% CI 67-93], PPV 14.3 [95% CI 1-58], NPV 96.8 [95% CI 81-100], accuracy of 81.6% [95%CI 65-92] and diagnostic odds ratio 5.0 [95% CI 0.3-91.5]. To diagnose tip colonisation (>15CFU), sensitivity of SQSC was 75% [95% CI 22-99], specificity 88.2% [95%CI 72-96], PPV 42.7 [95% CI 12-80], NPV96.8% [95% CI 81-100], accuracy 86.8% [95% CI 71-95] and diagnostic odds ratio 22.5 [95% CI 1.9-271.9]. For combined DTP blood cultures, sensitivity for CR-BSI was 50% [95% CI 3-97], with specificity 97% [95% CI 82-100], PPV 50% [5% CI 3-97%], NPV 97% [95% CI 82-100], accuracy 94.3% 95% CI 79-99] and diagnostic odds ratio 32 [95% CI 1.1-970.8]. CONCLUSION: Both DTP and SQSC displayed high specificity, NPV and accuracy in a population of adult burns patients. These features may make these tests useful for ruling out CR-BSI in this patient group. This study was limited by a low number of events and further research is required.

Microbial biofilms associated with intravascular catheter-related bloodstream infections in adult intensive care patients.

Catheter-related bloodstream infection (CRBSI) is one of the most serious complications in hospitalised patients, leading to increased hospitalisation, intensive care admissions, extensive antibiotic treatment and mortality. A greater understanding of these bacterial infections is needed to improve the prevention and the management of CRBSIs. We describe here the systematic culture-independent evaluation of intravascular catheter (IVC) bacteriology. Twelve IVCs (6 central venous catheters and 6 arterial catheters) were collected from 6 patients. By using traditional culture methods, 3 patients were diagnosed with catheter colonisation including 1 patient who also had CRBSI, and 3 had no colonisation. From a total of 839,539 high-quality sequence reads from high-throughput sequencing, 8 microbial phyla and 76 diverse microbial genera were detected. All IVCs examined in this study were colonised with complex microbial communities including "non-colonised IVCs," as defined using traditional culture methods. Two main community types were observed: Enterobacteriaceae spp., dominant in patients without colonisation or CRBSI; and Staphylococcus spp., dominant in patients with colonisation and CRBSI. More diverse pathogens and a higher microbial diversity were present in patients with IVC colonisation and CRBSI. Community composition did not appear to be affected by patients' antibiotic treatment or IVC type. Characterisation of these communities is the first step in elucidating roles of these pathogens in disease progression, and to ultimately facilitate the improved prevention, refined diagnosis and management of CRBSI.

Molecular investigation of bacterial communities on intravascular catheters: no longer just Staphylococcus.

Intravascular catheter-related bloodstream infections (IVC-BSIs) are associated with significant morbidity and mortality. Culture-independent molecular approaches can reveal and capture the composition of complex microbial communities, and are now being used to reveal "new" pathogens as well as the polymicrobial nature of some infections. Patients with concurrently sited arterial and central venous catheters who had clinically suspected IVC-BSIs, were examined by the high-throughput sequencing of microbial 16S rRNA. An average of 100 operational taxonomic units (OTUs, phylotypes) was observed on each IVC, indicating that IVCs were colonised by complex and diverse bacterial communities. Ralstonia (53 % of 16S rRNA sequences), Escherichia group (16 %), Propionibacterium (5 %), Staphylococcus (5 %), and Streptococcus (2 %) were the most abundant genera. There was no statistically significant difference in the bacterial communities examined from arterial and central venous catheters; from those with and without systemic antibiotic treatment; or from conventionally colonised and uncolonised IVCs. The genome of the predominant bacteria, R. pickettii AU12-08, was found to encode resistance to antimicrobial drugs of different classes. In addition, many encoded gene products are involved in quorum sensing and biofilm formation that would further contribute to increased antimicrobial drug resistance. Our results highlight the complex diversity of microbial ecosystems on vascular devices. High-throughput sequencing of 16S rRNA offers an insight into the pathogenesis of IVC-related infections, and opens up the scope for improving diagnosis and patient management.

Molecular investigation of bacterial communities on the inner and outer surfaces of peripheral venous catheters.

Peripheral venous catheters (PVCs) are some of the most widely used medical devices in hospitals worldwide. PVC-related infections increase morbidity and treatment costs. The inner surfaces of PVCs are rarely examined for the population structure of bacteria, as it is generally believed that bacteria at this niche are similar to those on the external surface of PVCs. We primarily test this hypothesis and also study the effect of antibiotic treatment on bacterial communities from PVC surfaces. The inner and outer surfaces of PVCs from 15 patients were examined by 454 GS FLX Titanium 16S rRNA sequencing and the culture method. None of the PVCs were colonised according to the culture method and none of the patients had a bacteraemia. From a total of 127,536 high-quality sequence reads, 14 bacterial phyla and 268 diverse bacterial genera were detected. The number of operational taxonomic units for each sample was in the range of 86-157, even though 60 % of patients had received antibiotic treatment. Stenotrophomonas maltophilia was the predominant bacterial species in all the examined PVC samples. There were noticeable but not statistically significant differences between the inner and outer surfaces of PVCs in terms of the distribution of the taxonomic groups. In addition, the bacterial communities on PVCs from antibiotic-treated patients were significantly different from untreated patients. In conclusion, the surfaces of PVCs display complex bacterial communities. Although their significance has yet to be determined, these findings alter our perception of PVC-related infections.

Therapeutic hypothermia following out-of-hospital cardiac arrest (OHCA): an audit of compliance at a large Australian hospital.

Therapeutic hypothermia (TH) is now largely considered the standard of care for patients following out-of-hospital cardiac arrest caused by ventricular arrhythmias, although the effective implementation of TH for individual patients can be challenging. This study aimed to document the effectiveness of TH when it is used at the discretion of treating physicians and not under the auspices of a research trial or protocol. A retrospective review of intensive care unit admissions over a four-year period detected 43 patients appropriate for TH. In the emergency department, only 20% of patients had TH commenced. Forty-four percent of patients required angiography in the cardiac catheterisation laboratory. It took, on average, 595 minutes for patients to reach their goal temperature, which was not reached at all in 13% of patients. Nineteen patients (44%) had a positive neurological outcome while 24 patients (56%) either died or had a poor neurological outcome. Without the control of a hospital protocol it was apparent that the implementation of TH in patients with an out-of-hospital cardiac arrest in our institution was inadequate. We recommend that TH is undertaken within the framework of a protocol that encompasses all the relevant departments.

Intensive care unit experience of haemopoietic stem cell transplant patients.

BACKGROUND: Previous research at our institution (1988-1998) established an intensive care unit (ICU) and hospital mortality between 70% and 80% in haemopoietic stem cell transplant (HSCT) patients requiring ICU admission. AIMS: This study explored mortality in a more contemporary cohort while comparing outcomes to published literature and our previous experience. METHODS: Retrospective chart review of HSCT patients admitted to ICU between December 1998 and June 2008. RESULTS: Of 146 admissions, 53% were male, with a mean age of 44 years, an Acute Physiologic and Chronic Health Evaluation II score of 28 and Sepsis Organ Failure Assessment score of 11. Fifty-six per cent had graft versus host disease (GVHD), with respiratory failure (67%) being the most common admission diagnosis. All but one received mechanical ventilation. The ICU and hospital mortality were 42% (72% 1988-1998 cohort) and 64% (82% 1998-1998 cohort) respectively. The 6- and 12-month survivals were 29% and 24% respectively for the 1998-2008 cohort. Dying in ICU was independently predicted by fungal infection (P= 0.02) and early onset of organ failure (P < 0.001), while GVHD (P= 0.04) predicted survival. Mortality at 12 months was independently predicted by the acute physiology score (P= 0.002), increasing number of organ failures (P= 0.001), and cytomegalovirus positive serology (P= 0.005), while blood stream infection (P= 0.003), an antibiotic change on admission to the ICU (P= 0.007) and a diagnosis of non-Hodgkin lymphoma (P= 0.02) predicted survival. CONCLUSION: Our study found that acute admission of HSCT patients to the ICU is associated with improved survival compared to our previous experience, with organ failure progression a strong predictor of ICU outcome, and specific disease characteristics contributing to long-term survival.

Unplanned early readmission to the intensive care unit: a case-control study of patient, intensive care and ward-related factors.

The purpose of this study was to identify patient, intensive care and ward-based risk factors for early, unplanned readmission to the intensive care unit. A five-year retrospective case-control study at a tertiary referral teaching hospital of 205 cases readmitted within 72 hours of intensive care unit discharge and 205 controls matched for admission diagnosis and severity of illness was conducted. The rate of unplanned readmissions was 3.1% and cases had significantly higher overall mortality than control patients (odds ratio [OR] 4.7, 95% confidence interval [CI] 2.1 to 10.7). New onset respiratory compromise and sepsis were the most common cause of readmission. Independent risk factors for readmission were chronic respiratory disease (OR 3.7, 95% CI 1.2 to 12, P = 0.029), pre-existing anxiety/depression (OR 3.3, 95% CI 1.7 to 6.6, P < 0.001), international normalised ratio >1.3 (OR 2.3, 95% CI 1.1 to 4.9, P = 0.024), immobility (OR 2.3, 95% CI 1.4 to 3.6, P = 0.001), nasogastric nutrition (OR 2.0, 95% CI 1.0 to 4.0, P = 0.041), a white cell count > 15 x 10(9)/l (OR 2.0, 95% CI 1.2 to 3.4, P = 0.012) and non-weekend intensive care unit discharge (OR 1.9, 95% CI 1.1 to 3.5, P = 0.029). Physiological derangement on the ward (OR 26, 95% CI 8.0 to 81, P < 0.001) strongly predicted readmission, although only 20% of patients meeting medical emergency team criteria had a medical emergency team call made. Risk of readmission is associated with both patient and intensive care factors. Physiological derangement on the ward predicts intensive care unit readmission, however, clinical response to this appears suboptimal.

Assessment of peripheral arterial catheters as a source of sepsis in the critically ill: a narrative review.

Intravascular devices (IVDs) are essential in the management of critically ill patients; however, IVD-related sepsis remains a major complication. Arterial catheters (ACs) are one of the most manipulated IVDs in critically ill patients. When bloodstream infection (BSI) is suspected in a patient with an IVD in situ, clinicians have focused their attention on the central venous catheter (CVC) while largely ignoring the AC. Although it would be routine for the CVC to be cultured and replaced if necessary for suspected IVD or catheter-related sepsis, the AC may not be treated in the same manner. The reasons for this may in part relate to the patient groups studied. In lower acuity patients with short dwell times, AC sepsis rates are indeed low. In the higher acuity patient, earlier studies suggested that ACs had an infective potential at least equal to short term CVCs, a finding that has translated poorly into clinical practice. It has been estimated that there may be up to 48,000 BSIs per year arising from ACs in the USA alone, suggesting a significant clinical problem. Recent evidence now shows that the infective potential of the AC is comparable with that in short term CVCs regarding both colonisation (which precedes BSI) and BSI, consolidating earlier studies. In critically ill patients suspected of catheter-related bloodsteam infection it is suggested that both the AC and CVC must now be assessed together.

Acquired hypernatraemia is an independent predictor of mortality in critically ill patients.

This study reports the incidence and associated mortality of acquired hypernatraemia (Na > 150 mmol x l(-1)) in a general medical/surgical intensive care unit. Patients admitted over a 5-year period with normal sodium values were eligible for inclusion; exclusions were made for burn/neurosurgical diagnoses and for hypertonic saline therapy. From 3475 admissions (3317 patients), 266 (7.7%) episodes of hypernatraemia were observed. Hospital mortality was 33.5% in the hypernatraemic group and 7.7% in the normonatraemic group (p < 0.001). Acquired hypernatraemia was an independent risk factor for in-hospital mortality (OR 1.97, 95% CI 1.37-2.82, p < 0.001). Intermediate sodium levels (145-150 mmol x l(-1)) were associated with increased mortality (OR 1.42, 95% CI 1.02-1.98). Uncorrected sodium at discharge (p = 0.001) and peak sodium (p = 0.001) were better predictors of mortality than time to onset (p = 0.71) and duration of hypernatraemia (p = 1.0). Hypernatraemia avoidance is justified, but determinants of hypernatraemia and benefits of targeted treatment strategies require further elucidation.

Intermittent enteral nutrition--a comparative study examining the effect on gastric pH and microbial colonization rates.

In a prospective randomized study we aimed to examine the effect on gastric pH and microbial colonization of enteral nutrition (EN) delivered both by intermittent and continual infusion. Forty-three mechanically ventilated patients were randomized to receive EN by one of three methods, intermittent or continual gastric or continual jejunal. We sampled gastric aspirate for pH and culture in all patients at 0600 hours and pH in gastric intermittent feeders at 2200 hours daily. Patients were studied for 12 days or until extubated. Data was obtained on 41 patients, of whom 73% had a diagnosis of trauma. Median APACHE II score was 17 and ventilation time 11 days. Twelve patients received gastric continuous, 15 gastric intermittent and 14 jejunal nutrition. No significant difference was observed between the three groups with regard to median 0600 pH (P = 0.16). This was lowest in the jejunal group (3.2) followed by the gastric intermittent group (4.0) and then gastric continuous group (5.0). With overnight cessation of EN in the gastric intermittent group, the median pH fell from 5.2 at 2200 to 4.0 at 0600 (P = 0.01) with no effect on gastric colonization. The probability of gastric colonization over time however was significantly lower in the jejunal group compared with the two gastric groups (Log rank test, P = 0.02). These results demonstrate that in a patient population consisting predominantly of trauma, overnight cessation of EN made no overall difference to 0600 gastric pH or colonization rates. The preservation of pH and lowered colonization in those given jejunal feeding may have implications in the pathogenesis of ventilator-associated infection and may warrant further study using larger patient numbers.

Severe community acquired pneumonia: a one-year analysis in a tertiary referral intensive care unit.

AIMS: To define outcomes, characteristics, microbiology and salient prognostic factors of patients admitted to our intensive care unit (ICU) with severe community acquired pneumonia, over a one year period. METHODS: All adult patients with severe community acquired pneumonia admitted between July 1997 and July 1998 were studied. Data were extracted by retrospective chart review. Variables assessed included underlying conditions and baseline physical parameters. Evolutionary variables eg, septic shock and laboratory data including microbiology and arterial blood gas determinants were also assessed. Prognostic factors were determined by comparison of the above variables between survivors and non-survivors. The prognostic value of the British Thoracic Society discriminant 'rule one' was assessed. Results. 32 patients were assessed. ICU mortality was 31%. 84% of patients had co-morbidity. The average age was 58.5 (SD 17.4) years and the average APACHE 11 score was 20.37 (SD 9.12). A microbiological diagnosis was made in 40%. Mortality was not increased in those in whom a bacterial diagnosis was not made. Commonest pathogens isolated were Streptococcus pneumoniae (46%), gram negative organisms (29%) and Staphylococcus aureus (23%). Prognostic factors on and during ICU admission were the need for mechanical ventilation (p=0.0003), septic shock (p=0.02), inotrope requirement (p=0.003), low serum albumin (p=0.041), base deficit (p=0.04), INR (p=0.02) and inspired oxygen concentration (p=0.003). On initial admission to hospital the presence of bilateral pneumonia was the only variable correlated with outcome (p=0.01). The British Thoracic Society 'rule one' did not correlate with death either on admission to hospital or ICU. CONCLUSIONS: Severe community acquired pneumonia carries a high mortality despite ICU management. Bacterial diagnostic rate was low but made no difference to mortality. Streptococcus pneumoniae was the commonest causative pathogen. The development of septic shock, requirement for mechanical ventilation and bilateral disease are important adverse prognostic indicators.

Glasgow Coma Scale: variation in mortality among permutations of specific total scores.

OBJECTIVE: The objective of this study was to determine whether different score permutations of the Glasgow Coma Scale (GCS) giving the same GCS total score were associated with significantly different mortality. DESIGN: For each GCS total we compared the mortality associated with each of the different GCS permutations using a Fisher's exact test. The relationship between components of the GCS score and mortality was also examined using uni- and multivariate logistic regression. SETTING: Data were collected from the intensive care unit at Wellington Hospital, a multidisciplinary, tertiary referral unit. PATIENTS: We analysed the GCS and mortality data from all admissions over a 4 year period (January 1994-January 1998). Patients with GCS scores of 3 or 15 were excluded, since these two total scores do not have multiple permutations, leaving 1,390 patients with GCS scores of 4-14 for analysis. RESULTS: The incidence of mortality was significantly different for the different permutations for total GCS scores of 7, 9, 11 and 14. CONCLUSIONS: It is possible for patients to have the same total GCS score, but significantly different risks of mortality due to differences in the GCS profile making up that score. This suggests that GCS scores may be more useful reported in terms of profiles rather than totals. This could also have implications for the use of other scoring systems such as Acute Physiology and Chronic Health Evaluation and Simplified Acute Physiology Score.

Streptoccocus pyogenes: a forgotten cause of severe community-acquired pneumonia.

We report a case of severe community-acquired pneumonia caused by Streptococcus pyogenes (Lancefield Group A streptoccocus) that was complicated by a streptococcal toxic shock syndrome. Although this micro-organism is an uncommon cause of community-acquired pneumonia, previously well individuals may be infected and the clinical course may be fulminant. A household contact was the likely point of infection. Invasive group A streptococcal disease continues to remain an important cause of morbidity and mortality in the community and therefore will continue to be encountered by intensive care physicians. Treatment of Group A streptococcal infection remains penicillin; however, clindamycin should be added in severe infection.

Traumatic laryngeal injury in a nine year old child--the 'padded dash' syndrome revisited.

A case is presented of a 9-year-old girl who sustained a traumatic injury to the larynx following a frontal impact motor vehicle accident. The type of injury sustained was typical of what is now called the 'padded dash' syndrome. On impact the anterior aspect of the neck strikes the car dashboard resulting in the larynx being crushed against the vertebral column. The victim is often unrestrained. The injury was detected only at extubation whereupon severe respiratory distress ensued. Injury to the larynx is uncommon at all ages, even more so in children. In the paediatric age group signs and symptoms may be minimal and a high index of suspicion is required. The diagnosis and management of these injuries with special reference to childhood is discussed.

Central venous catheter-related bloodstream infections: an analysis of incidence and risk factors in a cohort of 400 patients.

OBJECTIVE: To determine the incidence of central catheter-related bloodstream infection (CR-BSI) and to compare patient and catheter characteristics of those with and without CR-BSI from a clinically suspected subgroup. Secondly, to assess the efficacy of the acridine orange leucocyte cytospin test (AOLC) as a rapid in situ method of detecting central venous catheter (CVC) infection. DESIGN: One-year prospective audit. SETTING: Intensive care unit/high dependency unit (ICU/HDU) and general wards of a tertiary referral hospital. PATIENTS AND PARTICIPANTS: 400 patients with non-tunnelled CVCs. INTERVENTIONS: Daily surveillance, blood culture from peripheral venepuncture, blood sample from the CVC for assessment of the AOLC test and removal of suspected CVCs were carried out on patients clinically suspected of having CR-BSI. MEASUREMENTS AND RESULTS: CR-BSI was diagnosed using well defined criteria. Infection rate was calculated by dividing the number of definitive catheter associated infections by the total number of appropriate catheter in situ days. The AOLC test was performed on all those with suspected CR-BSI. A total of 499 CVCs in 400 patients were assessed, representing 3014 catheter in situ days. Over 80 % of patients were from our ICU/HDU, representing 404 CVCs and 1901 catheter in situ days. A total of 49/499 (9.8%) CVCs in the same number of patients were suspected of being infected subsequently 12/499 (2.4 %) CVCs [95% confidence interval (CI) 1.25 to 4.16] in 12 separate patients were demonstrated to be the direct cause of the patient's BSI. Rates of CR-BSI per 1000 catheter days were 3.98 (95 % CI 2.06 to 6.96) for the whole cohort and 4.20 (95 % CI 1.81 to 8.29) for the ICU/HDU subgroup. In the group suspected of having CR-BSI, CVCs were removed unnecessarily in 55 %, and no patient or catheter variables measured were predictive of the development of CR-BSI. The AOLC test was negative in all 12 catheters subsequently shown to be the definitive cause of BSI. CONCLUSIONS: We have defined the incidence of CR-BSI in a cohort of patients from a tertiary referral hospital, the rates comparing favourably with those reported for similar populations. We were unable to demonstrate significant differences in any patient or catheter variables between those with and without CR-BSI. The AOLC test used alone was unhelpful as a method to diagnose in situ CVC infection in this patient population.

Explosion and fire in the expiratory limb of a Fisher and Paykel "three in one" respiratory care system.

We report an incident involving a Fisher and Paykel "There in One Respiratory Care System" (Fisher and Paykel Healthcare, Auckland, New Zealand). This is a new ventilator circuit designed to be adaptable to the needs of ventilator, intubated CPAP, and mask therapies. In this case the patient had received eight hours of CPAP therapy overnight, during which time the "Three in One" circuit had been broken down to the CPAP configuration. The expiratory limb heater element, normally disconnected, was inadvertently left connected to the heater base. Under the extreme conditions of heating under "no gas flow" mode, the heater element malfunctioned. As a result when the circuit was reconfigured to provide pressure-supported ventilation, in the high oxygen environment of the expiratory limb (FiO2 0.5), ignition and combustion of the respiratory circuit occurred. The case is reported because of the potentially serious consequences and because the incident prompted the manufacturer to redesign and change componentry in parts of the circuit implicated.