Extended-spectrum beta-lactamase-producing Enterobacter cloacae in mobile dialysis units in the medical and surgical departments of a university hospital: a case-control study.

The objective of this case-control study was to investigate the source of contamination and risk factors for colonisation and infection during an outbreak of extended-spectrum beta-lactamase (ESBL)-producing Enterobacter cloacae in the University Medical Center Freiburg. A risk factor analysis was performed on 23 patients with ESBL-producing E. cloacae in the medical and surgical departments by comparing them with 46 non-colonised controls, who were matched for ward and length of hospital stay. For these, a risk factor analysis was conducted. Suspected sources for transmission of ESBL were examined and staff received training in infection control measures. The higher risk in colonised patients was attributed to dialysis with mobile units [odds ratio (OR): 4.00; 95% confidence interval (CI): 1.05-15.234; P=0.04]. Dialysis units were examined, but no contamination was found. Improvement in dialysis procedures, additional staff training and renewed training in standard precautions led to a substantial fall in case numbers. Risk factor analysis showed that colonised patients carried more invasive devices than controls (central venous catheter: OR: 2.50; 95% CI: 0.74-8.45; P=0.14; Foley catheter: 5.08; 0.61-42.23; P=0.13) and were given a greater number of different antibiotics (penicillins: 2.52; 0.71-8.89; P=0.15; fluoroquinolones: 2.37; 0.77-7.28; P=0.13). The differences in mobile dialysis frequency and antibiotic use between cases and controls were relevant, although the latter was not statistically significant. It was possible to contain the high frequency of ESBL colonisation or infection by reinforcing infection control measures and training the staff involved.

Risk factor analysis of blood stream infection and pneumonia in neutropenic patients after peripheral blood stem-cell transplantation.

The purpose of this study was to analyse risk factors for blood stream infection (BSI) and pneumonia in neutropenic patients who have undergone peripheral blood stem-cell transplantation (PBSCT). Data were taken from the ONKO-KISS multicenter surveillance project. Infections were identified using CDC definitions (laboratory-confirmed BSI) and modified criteria for pneumonia in neutropenic patients. The multivariate analysis was performed using the Fine-Gray regression model for the cumulative incidences of the competing events 'infection', 'death' and 'end of neutropenia'. The risk factors investigated were: sex, age, underlying disease and type of transplant. From January 2000 to June 2004, a total of 1699 patients in 20 hospitals were investigated. In the multivariate analysis, male patients had a significantly higher risk of acquiring BSI than female patients (P=0.002). The risk of acquiring BSI is highest in patients with advanced acute myeloid leukaemia (AML). In the univariate and multivariate analysis, unrelated donor allogeneic transplantation constituted a risk factor for pneumonia (P=0.012). ONKO-KISS provides reference data on the incidence of pneumonia and BSI. The increased risk for BSI in males and patients with advanced AML, and the increased risk for pneumonia in unrelated donor allogeneic PBSCT patients should be targeted to prevent infections in these higher risk groups.

Comparison in a laboratory model between the performance of a urinary closed system bag with double non-return valve and that of a single valve system.

BACKGROUND: Catheter-associated urinary tract infection is the most common nosocomial infection in clinical settings. For bacteria ascending to the bladder the most common route is the extraluminal, but the intraluminal route also plays a role. For this reason, we compared two urinary closed system bags (CSB), one with a double and the other with a single non-return valve (NRV), in a laboratory setting in order to establish their ability to prevent or delay the ascent of bacteria from the drainage bag to the bladder. PATIENTS AND METHODS: The tests were performed in two microbiological laboratories (Copenhagen (C), Denmark and Freiburg (F), Germany). These were blinded to each other. A urinary tract model using artificial urine was set up. Two sets of ten drainage bags each with a double NRV (CSB A), and two sets of ten drainage bags each with a single NRV (CSB B) were inoculated with Escherichia coli (F: ATCC 25922; C: clinical strain). Daily samples were taken from two drainage ports on each system - one above the NRV (Port I), the other above the top of the artificial bladder (Port II). Time till E. coli was detected at the drainage ports (time to positivity) was measured. Colonization of the 'bladder' was defined as time to positivity at Port II. RESULTS: No significant differences in time to positivity at Port I (median 9.0, range: 6-12 for CSB B vs median 9.5 days, range: 6-13 for CSB A) were observed between the two systems. However, substantial differences were seen between the two systems in time to positivity at Port II: Port II on the bladder model using CSB B became positive after a median of 14.0 days (range: 10-22), whereas Port II of the model using CSB A only became positive after 21.5 days (range: 13-24). This amounts to a highly significant difference of 7.5 days (p = 0.0001) in the mean. CONCLUSION: Under laboratory conditions, colonization of the 'bladder' was significantly delayed when the CSB with a double NRV was used in comparison to the results obtained from the single NRV-system. Clinical trials should be conducted to investigate whether the urinary CSB with the double NRV has the ability to prevent (or to delay the onset of) catheter-associated urinary tract infection.

Surveillance of nosocomial sepsis and pneumonia in patients with a bone marrow or peripheral blood stem cell transplant: a multicenter project.

BACKGROUND: For surveillance of nosocomial bloodstream infections (BSIs) and pneumonia during neutropenia in adult patients who have undergone bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT), a multicenter study--the Hospital Infection Surveillance System for Patients with Hematologic/Oncologic Malignancies (ONKO-KISS)--was initiated in Germany in 2000. METHODS: Nosocomial infections were identified in neutropenic patients by means of Centers for Disease Control and Prevention definitions for laboratory-confirmed BSI and modified criteria for pneumonia. RESULTS: During the first 38-month period of the study (i.e., through December 2003), a total of 1899 patients associated with 28,273 neutropenic days were investigated. Of these, 1173 (62%) had undergone allogeneic and 726 (38%) had undergone autologous BMT or PBSCT. The mean duration of neutropenia was 14.9 days (9.6 and 18.1 days after autologous and allogeneic transplantation, respectively). Overall, 395 BSIs and 168 cases of pneumonia were identified. The pooled mean site-specific incidence density per 1000 neutropenic days was 14.0 for BSI (12.4 and 18.9 for the allogeneic and autologous transplantation groups, respectively) and 5.9 for pneumonia (6.1 and 5.6 in the allogeneic and autologous transplantation groups, respectively). After allogeneic transplantation, 22.4 BSIs per 100 patients and 11.0 cases of pneumonia per 100 patients occurred, whereas 18.2 BSIs per 100 patients and 5.4 cases of pneumonia per 100 patients occurred after autologous transplantation. The majority (57%) of pathogens associated with BSI were coagulase-negative staphylococci. CONCLUSIONS: The ongoing ONKO-KISS project provides unprecedented reference data about the incidence of pneumonia and sepsis among BMT recipients and PBSCT recipients in Germany. These data will be used for further evaluation of the impact of hygiene measures and therapeutic regimens for these patients.