Advances in Mimivirus pathogenicity.

Viral diseases in the clinical setting have been extensively investigated. Viruses are now considered as potentially responsible for nosocomial infections, especially in intensive care unit (ICU) patients. Mimivirus is the largest virus known to date. Recent studies have suggested that Mimivirus could be responsible for both community-acquired and nosocomial pneumonia. These studies were mainly based on serologic diagnosis, which showed patients with community-acquired pneumonia have more antibodies to Mimivirus than healthy controls. Serologic evidence of Mimivirus pneumonia was also found in mechanically ventilated ICU patients. In a matched-cohort study in which ICU patients with serologic evidence of Mimivirus pneumonia were matched to ICU patients remaining seronegative for Mimivirus, positive serology was associated with an increased duration of both mechanical ventilation and ICU stay. Identification by PCR techniques remains difficult, probably because of the high level of polymorphism of nucleotide sequences of giant viruses. More studies are needed to confirm the clinical impact of Mimivirus in humans.

Pulmonary capillary blood flow and cardiac output measurement by partial carbon dioxide rebreathing in patients with acute respiratory distress syndrome receiving lung protective ventilation.

BACKGROUND: Partial carbon dioxide rebreathing noninvasively measures the pulmonary capillary blood flow and estimates the cardiac output with the use of a predicted shunt value. It has been reported that the accuracy of the method is decreased in patients with high pulmonary shunt. The aim of this study was to investigate the agreement between partial rebreathing and thermodilution for the determination of pulmonary capillary blood flow and cardiac output in the setting of acute respiratory distress syndrome. METHODS: Twenty consecutive patients with the acute respiratory distress syndrome were enrolled. Ventilator settings include low tidal volume (6 ml x kg(-1)) and positive end-expiratory pressure + 2 cm H2O higher than the lower inflection point if present or 10 cm H2O if not. Seven pairs of cardiac output and pulmonary capillary blood flows were recorded every 20 min over a 2-h period. The authors determined bias, SD, limit of agreement (95% confidence interval) and percentage error. RESULTS: Bias and agreement for cardiac output measurement were 0.8 +/- 1.2 l x min(-1) (-2.1 to 3.7 l x min(-1)), and percentage error was 36%. Bias and agreement for pulmonary capillary blood flow measurement were -0.1 +/- 0.8 l x min(-1) (-2.1 to 1.9 l x min(-1)), and percentage error was 35%. Dead space, arteriovenous oxygen content difference, mean pulmonary arterial pressure, and baseline cardiac output were independently associated with differences between methods. CONCLUSIONS: In patients with the acute respiratory distress syndrome, partial rebreathing cannot yet replace thermodilution for measuring pulmonary capillary blood flow or cardiac output. However, accuracy of the method is close to the boundary of clinical relevance.

Clinical significance of a positive serology for mimivirus in patients presenting a suspicion of ventilator-associated pneumonia.

OBJECTIVE: A seroconversion to mimivirus has been observed in patients with community-acquired or nosocomial pneumonia. The aim of this study was to determine whether a positive serology for mimivirus was associated with increased morbidity and mortality in patients with a suspicion of ventilator-associated pneumonia (VAP). DESIGN: Prospective matched-cohort study. SETTING: A 12-bed medical intensive care unit (ICU) in a teaching hospital. PATIENTS: Patients ventilated for at least 2 days presenting with a suspicion of VAP. Patients with a positive serology for mimivirus were matched to seronegative patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Matching criteria were: 1) the same main diagnosis on ICU admission, 2) the same age (+/- 10 yrs), 3) the same Simplified Acute Physiology II score (+/-10 points), 4) the same McCabe and Jackson comorbidity score, 5) admission within 1 year, and 6) diagnosis of at least one bacterial VAP during the ICU stay or not. A total of 55 pairs were submitted for analysis. The effectiveness of matching was 94.8%. Patients with a positive serology for mimivirus had longer duration of mechanical ventilation and ICU stay with median excesses of 7 days and 10 days, respectively. There was no difference in ICU mortality. The duration of mechanical ventilation before bronchoalveolar lavage (adjusted odds ratios [OR]1.08, p = 0.02), viral identification other than mimivirus during ICU stay (adjusted OR 0.32, p = 0.05), and enteral nutrition (adjusted OR 0.13, p = 0.01) were associated with positive serology for mimivirus. CONCLUSION: A positive serology for mimivirus is associated with a poorer outcome in mechanically ventilated ICU patients.

Decreased rates of nosocomial endometritis and urinary tract infection after vaginal delivery in a French surveillance network, 1997-2003.

OBJECTIVES: To identify independent risk factors for endometritis and urinary tract infection (UTI) after vaginal delivery, and to monitor changes in nosocomial infection rates and derive benchmarks for prevention. DESIGN: Prospective study. METHODS: We analyzed routine surveillance data for all vaginal deliveries between January 1997 and December 2003 at 66 maternity units participating in the Mater Sud-Est surveillance network. Adjusted odds ratios for risk of endometritis or UTI were obtained using a logistic regression model. RESULTS: The overall incidence rates were 0.5% for endometritis and 0.3% for UTI. There was a significant decrease in the incidence and risk of endometritis but not of UTI during the 7-year period. Significant risk factors for endometritis were fever during labor, parity of 1, and instrumental delivery and/or manual removal of the placenta. Significant risk factors for UTI were urinary infection on admission, premature rupture of membranes (more than 12 hours before admission), blood loss of more than 800 mL, parity of 1, instrumental delivery, and receipt of more than 5 vaginal digital examinations. Each maternity unit received a poster showing graphs of the number of expected and observed cases of UTI and endometritis associated with vaginal deliveries, which enabled each maternity unit to determine their rank within the network and to initiate prevention programs. CONCLUSIONS: Although routine surveillance means additional work for maternity units, our results demonstrate the usefulness of regular targeted monitoring of risk factors and of the most common nosocomial infections in obstetrics. Most of the information needed for monitoring is already present in the patients' records.

Downward trends in surgical site and urinary tract infections after cesarean delivery in a French surveillance network, 1997-2003.

OBJECTIVE: To evaluate whether the adjusted rates of surgical site infection (SSI) and urinary tract infection (UTI) after cesarean delivery decrease in maternity units that perform active healthcare-associated infection surveillance. DESIGN: Trend analysis by means of multiple logistic regression. SETTING: A total of 80 maternity units participating in the Mater Sud-Est surveillance network. PATIENTS: A total of 37,074 cesarean deliveries were included in the surveillance from January 1, 1997, through December 31, 2003. METHODS: We used a logistic regression model to estimate risk-adjusted post-cesarean delivery infection odds ratios. The variables included were the maternity units' annual rate of operative procedures, the level of dispensed neonatal care, the year of delivery, maternal risk factors, and the characteristics of cesarean delivery. The trend of risk-adjusted odds ratios for SSI and UTI during the study period was studied by linear regression. RESULTS: The crude rates of SSI and UTI after cesarean delivery were 1.5% (571 of 37,074 patients) and 1.8% (685 of 37,074 patients), respectively. During the study period, the decrease in SSI and UTI adjusted odds ratios was statistically significant (R=-0.823 [P=.023] and R=-0.906 [P=.005], respectively). CONCLUSION: Reductions of 48% in the SSI rate and 52% in the UTI rate were observed in the maternity units. These unbiased trends could be related to progress in preventive practices as a result of the increased dissemination of national standards and a collaborative surveillance with benchmarking of rates.