Nebulized colistin provides rapid and efficient bacterial killing in ventilated piglets with inoculation pneumonia caused by Pseudomonas aeruginosa.

The diagnostic accuracy of protected-specimen brush (PSB), bronchoalveolar lavage (BAL), and endotracheal aspirates (EA) was prospectively evaluated in a series of 28 mechanically ventilated patients (MV patients) who died within 3 d of the bronchoscopic procedure, using postmortem lung examination as the gold standard for establishing the diagnosis of pneumonia. The entire fixed lungs were carefully dissected along the bronchovascular axes and each segment was cut into 5- to 10-mm thick sections, enabling gross examination of the lung parenchyma. Two tissue blocks were taken from each segment, including grossly abnormal areas whenever present. In several cases, two peripheral (subpleural) lung-tissue blocks were also taken from each lobe prior to systematic dissection of the lungs. Quantitative cultures (QC) and direct cytologic and microbiologic examination (DE) was performed on respiratory samples obtained within 72 h before death. Values of 10(3) cfu/ml of Ringer's solution, 10(4) cfu/ml of retrieved fluid, and 10(6) cfu/ml of respiratory secretions were used as cutoff points for quantitative PSB, BAL, and EA cultures, respectively. The main findings in this study were that: (1) Pneumonia was present in 67% of the patients. (2) Histologic lesions of pneumonia were mainly bilateral and predominated in the dependent lung segments. (3) Coexistence of a variety of noninfectious processes was a common finding in patients with pneumonia. (4) In several cases pneumonia was absent from peripheral lung samples while more central areas of the same segment displayed typical foci of pneumonia. (5) The sensitivity of quantitative cultures was 55%, 57%, and 47% for EA, PSB, and BAL, respectively, and the specificity was 85%, 88%, and 100%, respectively. Reducing the diagnostic threshold of EA to 10(5) cfu/ml of respiratory secretions instead of 10(6) cfu/ml resulted in a sensitivity of 63.1% and a specificity of 75% for EA. The sensitivity of direct examination (DE) was 50%, 47%, and 47%, respectively, and the specificity was 75%, 88%, and 87%. (6) The presence of intracellular organisms (ICO) in BAL had a 36.8% sensitivity and 100% specificity in establishing the diagnosis of pneumonia regardless of their percentage. (7) Although 15 patients (53%) were not on antibiotics or were off antibiotics for more than 48 h before testing, no relationship could be established between the patients' antibiotic status and the result of any diagnostic test. By using a recommended methodology for respiratory sampling techniques together with complete postmortem lung examination as a diagnostic "gold standard," this study provides a realistic insight into the diagnostic values of EA, PSB, and BAL in MV patients with suspected pneumonia.

The objective of this prospective cohort study was to determine whether admission to an intensive care unit (ICU) room previously occupied by a patient with multidrug-resistant (MDR) Gram-negative bacilli (GNB) increases the risk of acquiring these bacteria by subsequent patients. All patients hospitalized for >48 h were eligible. Patients with MDR GNB at ICU admission were excluded. The MDR GNB were defined as MDR Pseudomonas aeruginosa, Acinetobacter baumannii and extended spectrum β-lactamase (ESBL) -producing GNB. All patients were hospitalized in single rooms. Cleaning of ICU rooms between two patients was performed using quaternary ammonium disinfectant. Risk factors for MDR P. aeruginosa, A. baumannii and ESBL-producing GNB were determined using univariate and multivariate analysis. Five hundred and eleven consecutive patients were included; ICU-acquired MDR P. aeruginosa was diagnosed in 82 (16%) patients, A. baumannii in 57 (11%) patients, and ESBL-producing GNB in 50 (9%) patients. Independent risk factors for ICU-acquired MDR P. aeruginosa were prior occupant with MDR P. aeruginosa (OR 2.3, 95% CI 1.2-4.3, p 0.012), surgery (OR 1.9, 95% CI 1.1-3.6, p 0.024), and prior piperacillin/tazobactam use (OR 1.2, 95% CI 1.1-1.3, p 0.040). Independent risk factors for ICU-acquired A. baumannii were prior occupant with A. baumannii (OR 4.2, 95% CI 2-8.8, p <0.001), and mechanical ventilation (OR 9.3, 95% CI 1.1-83, p 0.045). Independent risk factors for ICU-acquired ESBL-producing GNB were tracheostomy (OR 2.6, 95% CI 1.1-6.5, p 0.049), and sedation (OR 6.6, 95% CI 1.1-40, p 0.041). We conclude that admission to an ICU room previously occupied by a patient with MDR P. aeruginosa or A. baumannii is an independent risk factor for acquisition of these bacteria by subsequent room occupants. This relationship was not identified for ESBL-producing GNB.

Lung tissue deposition and antibacterial efficiency of nebulized and intravenous amikacin (AMK) were compared in anesthetized and ventilated piglets suffering from a bronchopneumonia produced by the intrabronchial inoculation of Escherichia coli. AMK was administered 24 hours after the inoculation either through an ultrasonic nebulizer (45 mg x kg-1, n = 10) or by intravenous infusion (15 mg x kg-1, n = 8). Piglets were killed 1 hour after a second AMK administration performed 24 hours after the first one, and lung tissue concentrations of AMK and lung bacterial burden were assessed on multiple lung specimens. The amount of nebulized AMK reaching the tracheobronchial tree represented 38 +/- 6% of the initial nebulizer AMK charge. After nebulization, AMK lung tissue concentrations were 3- to 30-fold higher than after intravenous administration and were influenced by the severity of lung lesions: 188 +/- 175 microg x g-1 in lung segments with mild bronchopneumonia versus 40 +/- 65 microg x g-1 in lung segments with severe bronchopneumonia (p < 0.01). Lung bacterial burden was significantly lower in the aerosol group than in the intravenous group (median = 0 colony forming units. g-1 versus median = 5 x 10(2) colony forming units x g-1, p < 0.001). In conclusion, the deposition of AMK in infected lung parenchyma and the efficiency of bacterial killing were greater after nebulization than after intravenous administration.

Background: To determine whether local complications at the site of pacemaker implantation indicate infection of the intravascular part of the lead as well as of the pacemaker pocket. Methods: 105 patients admitted for local inflammatory findings, impending pacemaker or lead exteriorisation, frank pacemaker or lead exteriorisation, or overt infection were studied prospectively. After systematic lead extraction, the initial clinical presentation was related to the results of lead cultures. Results: Regardless of the initial presentation, the intravascular parts of the leads gave positive cultures in 79.3% of patients. Additionally, 91.6% of the cultures of the extravascular lead segments were positive, in contrast to 38.1% positivity for wound swab cultures. No clinical observations or laboratory investigations permitted identification of patients with negative lead cultures. In a subgroup of 50 patients with manifestations strictly limited to the pacemaker implantation site, cultures of intravascular lead segments were positive in 72%. Infection recurred in 4/8 patients without complete lead body extraction (50%) v 1/97 patients (1.0%) whose leads were totally extracted (p , 0.001). Conclusions: Local complications at the site of pacemaker implantation are usually associated with infection of the intravascular part of the leads, with a risk of progressing to systemic infection. Such local symptoms should prompt the extraction of leads even in the absence of other infectious manifestations.

The objectives of the study were to determine the agreement between the protected specimen brush technique (PSB) with quantitative cultures and endotracheal aspirates (EA) with quantitative cultures when using increasing interpretative cutoff points and to investigate the respective operating characteristics for the diagnosis of pneumonia of PSB and EA when using quantitative cultures. Consecutive sampling of respiratory secretions using these two techniques was conducted in the respiratory intensive care units in 52 mechanically ventilated patients with clinical and radiologic suspicion of pneumonia. Quantitative bacterial cultures of PSB and EA samples were obtained. The 10(6) cfu/ml cutoff point was the most accurate diagnostic threshold for the EA technique. When using this threshold, there was a high level of agreement (84.6%) between PSB and EA results. Among the few discrepancies, the EA result was always indicative of pneumonia, whereas the PSB result was nonindicative, thus permitting us to classify correctly five patients in whom pneumonia would have been erroneously excluded on the basis of the sole result of PSB. Conversely, there was no case where the PSB result was indicative of pneumonia when the EA result (at the 10(6) cfu/ml level) was not. The operating characteristics of the PSB technique for the diagnosis of pneumonia were in accordance with previously published studies. The operating characteristics of the EA technique (when taking the 10(6) cfu/ml of respiratory secretions as the interpretative cutoff point) compared favorably with those of the PSB technique. Diagnostic accuracy rates were similar. The specificity of EA was somewhat lower (83 versus 96%), but the sensitivity was higher (82 versus 64%).(ABSTRACT TRUNCATED AT 250 WORDS)

Prosthetic vascular graft infection (PVGI) is a devastating complication, with a mortality rate of up to 75%, which is especially caused by aortic graft infection. The purpose of this study was to evaluate factors associated with in-hospital mortality of patients with definite graft infection, and with long-term outcome. We reviewed medical records of 85 patients treated for PVGIs defined by positive bacterial culture of intraoperative specimens or blood samples, and/or clinical, biological and radiological signs of infection. In-hospital patient mortality was defined as any death occurring during the initial treatment of the graft infection. Cure was defined as the absence of evidence of relapsing infection during long-term follow-up (≥1 year). Eighty-five patients (54 aortic and 31 limb graft infections) treated by surgical debridement and removal of the infected prosthesis (n=41), surgical debridement without removal of prosthesis (n=34) or antimicrobial treatment without surgery (n=10) were studied. The only microbiological difference observed between patients with early (occurring within 4 months after surgery) vs. late PVGI and between those with aortic vs. limb PVGI was the incidence of PVGI caused by Staphylococcus aureus, which was greater in patients with limb PVGI. Overall cure was observed in 93.2% of 59 patients with a follow-up of a minimum of 1 year. Overall in-hospital mortality was 16.5% (n=14). Two variables were independently associated with mortality: age >70 years (OR 9.1, 95% CI 1.83-45.43, p 0.007) and aortic graft infection (OR 5.6, 95% CI 1.1-28.7, p 0.037).

Early diagnosis of sepsis, rapid identification of the causative pathogen(s) and prompt initiation of appropriate antibiotic treatment have a combined impact on mortality due to sepsis. In this observational study, a new DNA-based system (LightCycler SeptiFast (LC-SF) test; Roche Diagnostics) allowing detection of 16 pathogens at the species level and four groups of pathogens at the genus level has been evaluated and compared with conventional blood cultures (BCs). One hundred BC and LC-SF results were obtained for 72 patients admitted to the intensive-care unit over a 6-month period for suspected sepsis. Microbiological data were compared with other biological parameters and with clinical data. The positivity rate of BCs for bacteraemia/fungaemia was 10%, whereas the LC-SF test allowed detection of DNA in 15% of cases. The LC-SF performance, based on its clinical relevance, was as follows: sensitivity, 78%; specificity, 99%; positive predictive value, 93%; and negative predictive value, 95%. Management was changed for four of eight (50%) of the patients because organisms were detected by the LC-SF test but not by BC. LC-SF results were obtained in 7-15 h, in contrast to the 24-72 h required for BC. According to the LC-SF results, initial therapy was inadequate in eight patients, and antibiotic treatment was changed. Our results suggest that the LC-SF test may be a valuable complementary tool in the management of patients with clinically suspected sepsis.