Trauma and Antimicrobial Resistance Are Independent Predictors of Inadequate Empirical Antimicrobial Treatment of Ventilator-Associated Pneumonia in Critically Ill Patients

Single-drug versus combination antimicrobial therapy in critically ill patients with hospital-acquired pneumonia and ventilator-associated pneumonia due to Gram-negative pathogens: a multicenter retrospective cohort study

KEY MESSAGES

In this study including 391 critically ill patients with nosocomial pneumonia due to Gram-negative pathogens, combination therapy was not associated with a reduced hazard of death at Day 28 or a greater likelihood of clinical cure at Day 14. No over-risk of AKI was observed in patients receiving combination therapy.

BACKGROUND

The benefits and harms of combination antimicrobial therapy remain controversial in critically ill patients with hospital-acquired pneumonia (HAP), ventilated HAP (vHAP) or ventilator-associated pneumonia (VAP) involving Gram-negative bacteria.

METHODS

We included all patients in the prospective multicenter OutcomeRea database with a first HAP, vHAP or VAP due to a single Gram-negative bacterium and treated with initial adequate single-drug or combination therapy. The primary endpoint was Day-28 all-cause mortality. Secondary endpoints were clinical cure rate at Day 14 and a composite outcome of death or treatment-emergent acute kidney injury (AKI) at Day 7. The average effects of combination therapy on the study endpoints were investigated through inverse probability of treatment-weighted regression and multivariable regression models. Subgroups analyses were performed according to the resistance phenotype of the causative pathogens (multidrug-resistant or not), the pivotal (carbapenems or others) and companion (aminoglycosides/polymyxins or others) drug classes, the duration of combination therapy (< 3 or ≥ 3 days), the SOFA score value at pneumonia onset (< 7 or ≥ 7 points), and in patients with pneumonia due to non-fermenting Gram-negative bacteria, pneumonia-related bloodstream infection, or septic shock.

RESULTS

Among the 391 included patients, 151 (38.6%) received single-drug therapy and 240 (61.4%) received combination therapy. VAP (overall, 67.3%), vHAP (16.4%) and HAP (16.4%) were equally distributed in the two groups. All-cause mortality rates at Day 28 (overall, 31.2%), clinical cure rate at Day 14 (43.7%) and the rate of death or AKI at Day 7 (41.2%) did not significantly differ between the groups. In inverse probability of treatment-weighted analyses, combination therapy was not independently associated with the likelihood of all-cause death at Day 28 (adjusted odd ratio [aOR], 1.14; 95% confidence interval [CI] 0.73-1.77; P = 0.56), clinical cure at Day 14 (aOR, 0.79; 95% CI 0.53-1.20; P = 0.27) or death or AKI at Day 7 (aOR, 1.07; 95% CI 0.71-1.63; P = 0.73). Multivariable regression models and subgroup analyses provided similar results.

CONCLUSIONS

Initial combination therapy exerts no independent impact on Day-28 mortality, clinical cure rate at Day 14, and the hazard of death or AKI at Day 7 in critically ill patients with mono-bacterial HAP, vHAP or VAP due to Gram-negative bacteria.

The impact of inspiratory pressure level on prevention of ventilator-associated pneumonia: A double-blind, randomized clinical trial

BACKGROUND

Atelectasis and pneumonia are highly prevalent in patients under mechanical ventilation. Studies indicate that using ventilation with an open lung concept improves recovery, decreases ventilator-related pneumonia, decreases mortality and leads to faster weaning from the ventilator. Therefore, this study investigated the effect of higher airway pressure on ventilator-associated pneumonia.

METHODS

This randomized clinical trial was conducted on 120 patients under mechanical ventilation. The patients were divided into two groups based on ventilator pressure: the control group (pressure level 20) and the intervention group (pressure level 30). Demographic data, disease severity, the incidence of ventilator-associated pneumonia, organ damage, days connected to the ventilator, length of hospitalization in ICU, and mortality were compared between the two groups.

RESULTS

There was no significant difference in demographic data and disease severity between the two groups. The average Clinical Pulmonary Infection Score in the intervention group was significantly lower than the control group (P = 0.02). The intervention group's average Sequential Organ Failure Assessment score was significantly lower than the control group (p = 0.016).

CONCLUSIONS

High-pressure levels can decrease ventilator-associated pneumonia and organ failure. It is recommended that the study be repeated with a larger, more diverse population.

Predicting pneumonia during hospitalization in flail chest patients using machine learning approaches

Objective

Pneumonia is a common pulmonary complication of flail chest, causing high morbidity and mortality rates in affected patients. The existing methods for identifying pneumonia have low accuracy, and their use may delay antimicrobial therapy. However, machine learning can be combined with electronic medical record systems to identify information and assist in quick clinical decision-making. Our study aimed to develop a novel machine-learning model to predict pneumonia risk in flail chest patients.

Methods

From January 2011 to December 2021, the electronic medical records of 169 adult patients with flail chest at a tertiary teaching hospital in an urban level I Trauma Centre in Chongqing were retrospectively analysed. Then, the patients were randomly divided into training and test sets at a ratio of 7:3. Using the Fisher score, the best subset of variables was chosen. The performance of the seven models was evaluated by computing the area under the receiver operating characteristic curve (AUC). The output of the XGBoost model was shown using the Shapley Additive exPlanation (SHAP) method.

Results

Of 802 multiple rib fracture patients, 169 flail chest patients were eventually included, and 86 (50.80%) were diagnosed with pneumonia. The XGBoost model performed the best among all seven machine-learning models. The AUC of the XGBoost model was 0.895 (sensitivity: 84.3%; specificity: 80.0%).Pneumonia in flail chest patients was associated with several features: systolic blood pressure, pH value, blood transfusion, and ISS.

Conclusion

Our study demonstrated that the XGBoost model with 32 variables had high reliability in assessing risk indicators of pneumonia in flail chest patients. The SHAP method can identify vital pneumonia risk factors, making the XGBoost model's output clinically meaningful.

Association of Multidrug Resistance Bacteria and Clinical Outcomes of Adult Patients with Sepsis in the Intensive Care Unit

Background: Multi-drug resistance organisms (MDRO) often cause increased morbidity, mortality, and length of stays (LOS). However, there is uncertainty whether the infection of MDRO increase the morbidity, mortality, and ICU-LOS. Objective: This study was performed to determine the prevalence of MDRO in the ICU, the site of infection, and the association of MDRO or site of infection with mortality. The secondary outcome was determined by ascertaining the association of MDRO or site of infection with ICU-LOS. Methods: A retrospective cohort study was performed with adult sepsis patients in the ICU. Univariate and multivariate (MVA) logistic regression with cox regression modeling were performed to compute the association of MDRO with ICU mortality. MVA modelling was performed for ICU-LOS predictors. Results: Out of 228 patients, the isolated MDRO was 97 (42.5%), of which 78% were Gram-negative bacteria. The mortality rate among those with MDRO was 85 (37.3%). The hospital acquired infection (HAI) was a significant predictor for ICU-LOS in univariate linear regression (R2 = 0.034, p = 0.005). In MVA linear regression, both Enterococcus faecalis infection and Acinetobacter baumannii (AC)-MDRO were predictors for ICU-LOS with (R2 = 0.478, p < 0.05). In the univariate cox regression, only the infection with AC-MDRO was a risk factor for ICU-mortality with [HR = 1.802 (95% CI: 1.2−2.706; p = 0.005)]. Conclusions: Identifying risk factors for MDRO addresses the appropriate administration of empirical antibiotics and allows to effectively control the source of infection, which would reduce mortality and ICU-LOS. The usage of broad-spectrum antibiotics should be limited to those with substantial risk factors for acquiring MDRO.

Risk factors and mortality associated with multidrug-resistant gram-negative bacterial infection in adult patients with abdominal surgery

BACKGROUND

Multidrug-resistant (MDR) gram-negative bacterial (GNB) infections remain a significant cause of morbidity and mortality among surgical patients. The objective of our study was to recognize the risk factors for MDR GNB infection in patients with abdominal surgery and determine the predictors independently associated with death.

METHODS

From 2010 to 2017, a retrospective cohort study was conducted among patients with abdominal surgery admitted in surgical intensive care unit (ICU). Patients with GNB infections were included for analyses.

RESULTS

A total of 364 patients with abdominal surgery experienced GNB infections, among them, 117 (32.1%) were MDR GNB infection. Of 133 MDR GNB isolates, the most frequent isolate was Escherichia coli (45.1%). Patients with MDR GNB infection had significantly longer ventilator days and hospital stay, as well as higher 30-day and in-hospital mortality compared to non-MDR GNB patients. Multivariable analysis showed longer length of pre-ICU stay, surgical re-exploration, receipt of group 2 carbapenems (e.g. imipenem, meropenem and doripenem) and fluoroquinolones, and higher total bilirubin were independent risk factors for the acquisition of MDR GNB infection. Predictors for 30-day mortality among patients with MDR GNB infection were chronic kidney disease, receipt of group 2 carbapenems and inappropriate empirical antimicrobial therapy.

CONCLUSIONS

This study provides important information about the risk factors for subsequent MDR GNB infection and 30-day mortality among the patients with abdominal surgery.