Impact of microbial ecology on accuracy of surveillance cultures to predict multidrug resistant microorganisms causing ventilator-associated pneumonia.

OBJECTIVES: The objective of this study was to assess surveillance cultures (SC) prediction accuracy in two periods and settings of the same Department with a different microbiological epidemiology (high and low prevalence of multi-drug resistant microorganisms (MDRM)). METHODS: Prospective and observational study. SC were obtained twice a week in consecutive mechanically ventilated patients. Patients fulfilling VAP criteria were analyzed. RESULTS: 440 patients were followed up, 71 patients had VAP (50 in period I and 21 in period II). MDRM causing VAP were more prevalent in the first period (48% vs. 19%; p = 0.033). The rate of empirical appropriate treatment in period I was lower than in period II (52% vs.76%; p = 0.031). SC prediction accuracy was similar in the two periods (80% vs. 81%; p = 0.744). However, if antibiotic treatment had been guided by SC, the percentage of appropriate treatment would have increased by 28% in the first period but only by 5% in the second; p = 0.024. CONCLUSIONS: SC were able to predict VAP etiology in 80% of cases regardless the prevalence of MDRM. However, the potential benefit of SC in terms of appropriate empirical treatment could be only observed when MDRM were prevalent.

Implications of endotracheal tube biofilm in ventilator-associated pneumonia response: a state of concept.

INTRODUCTION: Biofilm in endotracheal tubes (ETT) of ventilated patients has been suggested to play a role in the development of ventilator-associated pneumonia (VAP). Our purpose was to analyze the formation of ETT biofilm and its implication in the response and relapse of VAP. METHODS: We performed a prospective, observational study in a medical intensive care unit. Patients mechanically ventilated for more than 24 hours were consecutively included. We obtained surveillance endotracheal aspirates (ETA) twice weekly and, at extubation, ETTs were processed for microbiological assessment and scanning electron microscopy. RESULTS: Eighty-seven percent of the patients were colonized based on ETA cultures. Biofilm was found in 95% of the ETTs. In 56% of the cases, the same microorganism grew in ETA and biofilm. In both samples the most frequent bacteria isolated were Acinetobacter baumannii and Pseudomonas aeruginosa. Nineteen percent of the patients developed VAP (N = 14), and etiology was predicted by ETA in 100% of the cases. Despite appropriate antibiotic treatment, bacteria involved in VAP were found in biofilm (50%). In this situation, microbial persistence and impaired response to treatment (treatment failure and relapse) were more frequent (100% vs 29%, P = 0.021; 57% vs 14%, P = 0.133). CONCLUSIONS: Airway bacterial colonization and biofilm formation on ETTs are early and frequent events in ventilated patients. There is microbiological continuity between airway colonization, biofilm formation and VAP development. Biofilm stands as a pathogenic mechanism for microbial persistence, and impaired response to treatment in VAP.

Inflammatory biomarkers and prediction for intensive care unit admission in severe community-acquired pneumonia.

OBJECTIVE: Increased inflammatory response is related to severity and outcome in community-acquired pneumonia, but the role of inflammatory biomarkers in deciding intensive care unit admission is unknown. We assessed the relationship between inflammatory response, prediction for intensive care unit admission, delayed intensive care unit admission, and outcome in patients with community-acquired pneumonia. DESIGN: Prospective clinical study. SETTING: Intensive care units of two university hospitals. PATIENTS: We included 627 ward and 58 intensive care unit patients with community-acquired pneumonia, 36 with direct and 22 with delayed intensive care unit admission. INTERVENTIONS: Serum levels of C-reactive protein, procalcitonin, tumor necrosis factor-α, interleukin-1, interleukin-6, interleukin-8, and interleukin-10 at admission. MEASUREMENTS AND MAIN RESULTS: We assessed the prediction for intensive care unit admission of biomarkers and the Infectious Diseases Society of America/American Thoracic Society guidelines minor criteria for severe community-acquired pneumonia. Procalcitonin (p=.001), C-reactive protein (p=.005), tumor necrosis factor-α (p=.042), and interleukin-6 (p=.003) levels were higher in intensive care unit-admitted patients; however, the Infectious Diseases Society of America/American Thoracic Society guidelines minor severity criteria predicted better intensive care unit admission (odds ratio, 12.03; 95% confidence interval, 5.13-28.20; p<.001). No patient with severe community-acquired pneumonia by three or more minor severity criteria and procalcitonin levels below the optimal cutoff (0.35 ng/mL) needed intensive care unit admission compared with 14 (23%) with levels above the cutoff (p=.032). In patients initially admitted to wards, procalcitonin (p=.012) and C-reactive protein (p=.039) were higher in those 22 patients subsequently transferred to the intensive care unit after adjusting for age, comorbidities, and Pneumonia Severity Index risk class. Despite initially admitted to wards, 14 (64%) patients with delayed intensive care unit admission had already criteria for severe community-acquired pneumonia at admission compared with 73 (12%) ward patients (p<.001). CONCLUSION: Inflammatory biomarkers identified patients needing intensive care unit admission, including those with delayed intensive care unit admission. Patients with severe community-acquired pneumonia by minor criteria and low levels of procalcitonin may be safely admitted to wards. Correctly applying the Infectious Diseases Society of America/American Thoracic Society guidelines would reduce substantially delayed intensive care unit admission.

Diagnostic implications of soluble triggering receptor expressed on myeloid cells-1 in patients with acute respiratory distress syndrome and abdominal diseases: a preliminary observational study.

INTRODUCTION: Patients admitted to the intensive care unit (ICU) because of acute or decompensated chronic abdominal disease and acute respiratory failure need to have the potential infection diagnosed as well as its site (pulmonary or abdominal). For this purpose, we measured soluble triggering receptor expression on myeloid cells-1 (sTREM-1) in alveolar and peritoneal fluid. METHODS: Consecutive patients (n = 21) with acute or decompensated chronic abdominal disease and acute respiratory failure were included. sTREM was measured in alveolar (A-sTREM) and peritoneal (P-sTREM) fluids. RESULTS: An infection was diagnosed in all patients. Nine patients had a lung infection (without abdominal infection), 5 had an abdominal infection (without lung infection) and seven had both infections. A-sTREM was higher in the patients with pneumonia compared to those without pneumonia (1963 ng/ml (1010-3129) vs. 862 ng/ml (333-1011); P 0.019). Patients with abdominal infection had an increase in the P-sTREM compared to patients without abdominal infection (1941 ng/ml (1088-3370) vs. 305 ng/ml (288-459); P < 0.001). A cut-off point of 900 pg/ml of A-sTREM-1 had a sensitivity of 81% and a specificity of 80% (NPV 57%; PPV 93%, AUC 0.775) for the diagnosis of pneumonia. In abdominal infections, a cut-off point for P-sTREM of 900 pg/ml had the best results (sensitivity 92%; specificity 100%; NPV 90%, PPV 100%, AUC = 0.903). CONCLUSIONS: sTREM-1 measured in alveolar and peritoneal fluids is useful in assessing pulmonary and peritoneal infection in critical-state patients-A-sTREM having the capacity to discriminate between a pulmonary and an extra-pulmonary infection in the context of acute respiratory failure.

Bacterial translocation in heat stroke.

The scientific community is fully aware of the importance of heat-related illness and heat stroke syndrome. Numerous guidelines have been recently published and most of them agree on the key role played by the intestine. Likewise, the role of endotoxinemia in the pathophysiology is well established. However, the possibility of bacterial translocation is not mentioned. Our patient illustrates the likelihood of bacterial translocation in heat stroke and consistently the potential need of antibiotic therapy. A 45-year-old man diagnosed with paranoid schizophrenia was confined in a penitentiary center. One summer day in which a temperature of 41 degrees C was observed in the shade, the patient was found in deep coma with an axillary temperature of 42 degrees C. Multiorgan failure was detected in the hospital. Other causes of coma and/or hyperthermia were excluded, and heat stroke was diagnosed. Blood cultures were positive for Pseudomonas aeruginosa and Escherichia coli. Infection site was not identified despite of an exhaustive search. The patient fully recovered after 48 hours. On the basis of review of the literature, we think that bacterial translocation can take part in the pathophysiology of heat stroke. Therefore, antibiotic treatment must be evaluated in heat stroke patients.

Mobiluncus curtisii bacteremia.

Mobiluncus curtisii was isolated from the blood of a 35-year-old man with a medical history of ulcerative colitis who was admitted unconscious to the Intensive Care Unit (ICU). A CT scan revealed massive intracerebral hemorrhage in the left hemisphere. Temperature remained constant over 38.5 degrees C; therefore, two sets of blood cultures were collected. One anaerobic bottle BacT/ALERT SN (bioMerieux, France) was detected as positive after 5 days of incubation and a Gram stain confirmed a gram variable curved-shaped rod. The patient died 18 h after being admitted to the hospital.