Management of ventilator-associated pneumonia in a multidisciplinary intensive care unit: does trauma make a difference?

Narrowing antibiotic spectrum of activity for trauma-associated pneumonia through the use of a disease-specific antibiogram

Background

Organism susceptibilities for trauma-associated pneumonia (TAP) differ from those in other patient populations, including the critically ill. The purpose of this study was to identify common organisms and their susceptibilities in the respiratory isolates of trauma patients diagnosed with pneumonia within the first 7 days of hospital admission, and to create a TAP-specific disease-state antibiogram to guide empiric antibiotic therapy in this patient population.

Methods

This study was a retrospective review of adult trauma patients with pneumonia admitted between September 1, 2015 and August 31, 2018. Patients included were diagnosed with and treated for pneumonia, with respiratory cultures drawn within the first 7 hospital-days; both culture-positive and culture-negative patients were included. Subgroup antibiograms were made for diagnosis made on days 1-3, 4-5, and 6-7.

Results

There were 131 patients included with a median age of 45; 85% were male, and 31% were illicit drug users. Most patients (63%) had ventilator-associated pneumonia, and most respiratory samples (77%) were obtained via bronchoalveolar lavage. Cultures were positive in 109 patients and negative in 22. There were 144 total isolates; 54% were Gram-negative bacteria. The most common Gram-negative pathogens were Haemophilus influenzae (16%) and Klebsiella pneumoniae (15%). The most common Gram-positive pathogen was Staphylococcus aureus; methicillin-resistant S. aureus (MRSA) constituted 8% of all isolates. With culture-negative patients counted as susceptible, ceftriaxone monotherapy and ceftriaxone+vancomycin susceptibilities were 85% and 94%, respectively. Susceptibilities to cefazolin, ampicillin/sulbactam, cefepime, piperacillin/tazobactam, and levofloxacin were 49%, 69%, 91%, 90%, and 92%, respectively. Illicit drug use and day of pneumonia diagnosis did not appreciably affect antibiotic susceptibilities.

Conclusions

For TAP diagnosed within the first 7 days of hospital admission, ceftriaxone monotherapy is adequate as empiric therapy, including in ventilated patients. The addition of vancomycin can be considered in patients with MRSA risk factors or who are critically ill.

Level of evidence

Level III, prognostic and epidemiological.

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

Background: We aimed to assess independent risk factors for inadequate initial antimicrobial treatment (IAT) in critically ill patients with ventilator-associated pneumonia (VAP) treated in intensive care units (ICU) and to determine whether IAT is associated with adverse outcomes in patients with VAP. Patients and Methods: A prospective cohort study was performed and included 152 patients with VAP treated in an ICU for more than 48 hours. The main outcomes of interest were all-cause ICU mortality and VAP-related mortality. Other outcomes considered were: intra-hospital mortality, VAP-related sepsis, relapse, re-infection, length of stay in ICU (ICU LOS), and number of days on mechanical ventilation (MV). Results: One-third of patients (35.5%) received inadequate antimicrobial therapy. Trauma (odds ratio [OR], 3.55; 95% confidence interval [CI], 1.25-10.06) and extensively drug-resistant (XDR) causative agent (OR, 3.09; 95% CI, 1.23-7.74) were independently associated with inadequate IAT. Inadequate IAT was associated with a higher mortality rate (OR, 3.08; 95% CI, 1.30-7.26), VAP-related sepsis (OR, 2.39; 95% CI, 1.07-5.32), relapse (OR, 3.25; 95% CI, 1.34-7.89), re-infection (OR, 6.06; 95% CI, 2.48-14.77), and ICU LOS (β 4.65; 95% CI, 0.93-8.36). Acinetobacter spp., Pseudomonas aeruginosa and Klebsiella/Enterobacter spp. were the most common bacteria in patients with IAT and those with adequate antimicrobial therapy. Conclusions: This study demonstrated that inadequate IAT is associated with a higher risk of the majority of adverse outcomes in patients with VAP treated in ICUs. Trauma and XDR strains of bacteria are independent predictors of inadequate IAT of VAP in critically ill patients.

Worldwide variation in Pseudomonas associated ventilator associated pneumonia. A meta-regression

PURPOSE

The objective here is to define the extent and possible reasons for geographic variation in Pseudomonas aeruginosa associated with Ventilator Associated Pneumonia (VAP).

METHODS

A random effects meta-regression model of Pseudomonas associated VAP incidence within the published literature was undertaken incorporating group level factors such trauma admission, year of publication and use of bronchoscopic sampling towards VAP diagnosis.

RESULTS

Pseudomonas associated VAP incidence was reported in 162 studies from seven worldwide regions published over 30 years. The highest incidence is among reports from the Middle East and Mediterranean being respectively 6.8; 5.2-9.0 (mean; 95% CI) and 6.9; 5.4-8.8 per 1000 mechanical ventilation (MV) days, versus that from North American ICU's (3.7; 2.3-5.9). In a meta-regression model, the variation in the incidence of Pseudomonas associated VAP was not significantly associated with bronchoscopic sampling in the diagnosis of VAP (p = 0.12) nor with admission to a trauma ICU (p = 0.13).

CONCLUSION

Pseudomonas associated VAP incidence among reports from six geographic regions worldwide varies by less than twofold with some decline by year of publication. Trauma ICU admission is a significant factor underlying variations in incidence of VAP overall but not Pseudomonas associated VAP.

Risk factors for early-onset ventilator-associated pneumonia in aneurysmal subarachnoid hemorrhage patients

This study aimed to investigate the risk factors related to ventilator-acquired pneumonia (VAP) in aneurysmal subarachnoid hemorrhage (SAH) patients. From January 2011 to December 2015, a single-center retrospective study including 200 SAH patients requiring mechanical ventilation (MV) ≥48 h was performed. The clinical data of these patients were collected and analyzed. The age range of the patients were 41-63 and 72 (36%) were male. The Glasgow coma scale score range was 5-15 and the Simplified Acute Physiology Score II range was 31-52. One hundred and forty-eight (74%) patients had a World Federation of Neurosurgeons (WNFS) score ≥III. Aneurysm was secured with an endovascular coiling procedure in 168 (84%) patients and 94 (47%) patients presented VAP. Male gender (OR=2.25, 95%CI=1.15-4.45), use of mannitol (OR=3.02, 95%CI=1.53-5.94) and enteral feeding above 20 kcal·kg-1·day-1 (OR=2.90, 95%CI=1.26-6.67) after day 7 were independent factors for VAP. Patients with early-onset VAP had a longer duration of sedation (P=0.03), MV (P=0.001) and ICU length of stay (P=0.003) and a worse Glasgow Outcome Scale score (P<0.001), but did not have a higher death rate.

World-wide variation in incidence of Acinetobacter associated ventilator associated pneumonia: a meta-regression

Background

Acinetobacter species such as Acinetobacter baumanii are of increasing concern in association with ventilator associated pneumonia (VAP). In the ICU, Acinetobacter infections are known to be subject to seasonal variation but the extent of geographic variation is unclear. The objective here is to define the extent and possible reasons for geographic variation for Acinetobacter associated VAP whether or not these isolates are reported as Acinetobacter baumanii.

Methods

A meta-regression model of VAP associated Acinetobacter incidence within the published literature was undertaken using random effects methods. This model incorporated group level factors such as proportion of trauma admissions, year of publication and reporting practices for Acinetobacter infection.

Results

The search identified 117 studies from seven worldwide regions over 29 years. There is significant variation in Acinetobacter species associated VAP incidence among seven world-wide regions. The highest incidence is amongst reports from the Middle East (mean; 95 % confidence interval; 8.8; 6 · 2–12 · 7 per 1000 mechanical ventilation days) versus that from North American ICU’s (1 · 2; 0 · 8–2 · 1). There is a similar geographic related disparity in incidence among studies reporting specifically as Acinetobacter baumanii. The incidence in ICU’s with a majority of admission being for trauma is >2.5 times that of other ICU’s.

Conclusion

There is greater than fivefold variation in Acinetobacter associated VAP among reports from various geographic regions worldwide. This variation is not explainable by variations in rates of VAP overall, admissions for trauma, publication year or Acinetobacter reporting practices as group level variables.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1921-4) contains supplementary material, which is available to authorized users.

Empiric antimicrobial therapy for ventilator-associated pneumonia after brain injury

Issues regarding recommendations on empiric antimicrobial therapy for ventilator-associated pneumonia (VAP) have emerged in specific populations.To develop and validate a score to guide empiric therapy in brain-injured patients with VAP, we prospectively followed a cohort of 379 brain-injured patients in five intensive care units. The score was externally validated in an independent cohort of 252 brain-injured patients and its extrapolation was tested in 221 burn patients.The multivariate analysis for predicting resistance (incidence 16.4%) showed two independent factors: preceding antimicrobial therapy ≥48 h (p<0.001) and VAP onset ≥10 days (p<0.001); the area under the receiver operating characteristic curve (AUC) was 0.822 (95% CI 0.770-0.883) in the learning cohort and 0.805 (95% CI 0.732-0.877) in the validation cohort. The score built from the factors selected in multivariate analysis predicted resistance with a sensitivity of 83%, a specificity of 71%, a positive predictive value of 37% and a negative predictive value of 96% in the validation cohort. The AUC of the multivariate analysis was poor in burn patients (0.671, 95% CI 0.596-0.751).Limited-spectrum empirical antimicrobial therapy has low risk of failure in brain-injured patients presenting with VAP before day 10 and when prior antimicrobial therapy lasts <48 h.

α-Hemolysin activity of methicillin-susceptible Staphylococcus aureus predicts ventilator-associated pneumonia

RATIONALE

Colonization of lower airways by Staphylococcus aureus is a risk factor for the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). However, little is known about the virulence factors of methicillin-sensitive and -resistant S. aureus (MSSA and MRSA) that may influence host colonization and progression to VAT and VAP.

OBJECTIVES

We evaluated MRSA and MSSA endotracheal aspirates (ETA) for genotype and α-hemolysin activity in relation to the development of VAT and VAP.

METHODS

Serial S. aureus ETA isolates from ventilated patients were analyzed for methicillin resistance, molecular type by Multi-Locus Sequence Typing and spa-typing, and α-hemolysin activity by semiquantitative analysis of hemolysis on sheep blood agar and quantitative measurement of cytolysis of human lung epithelial cells. The virulence of selected strains was assessed in mice by intranasal challenge.

MEASUREMENTS AND MAIN RESULTS

We detected S. aureus from ETA samples in a quarter of the 231 ventilated patients analyzed; one-third of them developed VAP. VAP patients (n = 15) were mainly infected by MSSA strains (87%), whereas colonized individuals (n = 18) not progressing to disease mainly carried MRSA strains (68%). MSSA isolates from colonized or VAT patients exhibited significantly lower α-hemolysin activity than those from VAP cases; however, no such relationship was found with MRSA strains. α-Hemolysin activity of S. aureus isolates was predictive for virulence in mouse pneumonia model.

CONCLUSIONS

MSSA strains with strong blood agar hemolysis and high α-hemolysin activity are markers for VAP, but not VAT, and might be considered in differential diagnosis and initiation of therapy.

Implementation of an evidence-based extubation readiness bundle in 499 brain-injured patients. a before-after evaluation of a quality improvement project

RATIONALE

Mechanical ventilation is associated with morbidity in patients with brain injury.

OBJECTIVES

This study aims to assess the effectiveness of an extubation readiness bundle to decrease ventilator time in patients with brain injury.

METHODS

Before-after design in two intensive care units (ICUs) in one university hospital. Brain-injured patients ventilated more than 24 hours were evaluated during two phases (a 3-yr control phase followed by a 22-mo intervention phase). Bundle components were protective ventilation, early enteral nutrition, standardization of antibiotherapy for hospital-acquired pneumonia, and systematic approach to extubation. The primary endpoint was the duration of mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

A total of 299 and 200 patients, respectively, were analyzed in the control and the intervention phases of this before-after study. The intervention phase was associated with lower tidal volume (P < 0.01), higher positive end-expiratory pressure (P < 0.01), and higher enteral intake in the first 7 days (P = 0.01). The duration of mechanical ventilation was 14.9 ± 11.7 days in the control phase and 12.6 ± 10.3 days in the intervention phase (P = 0.02). The hazard ratio for extubation was 1.28 (95% confidence interval [CI], 1.04-1.57; P = 0.02) in the intervention phase. Adjusted hazard ratio was 1.40 (95% CI, 1.12-1.76; P < 0.01) in multivariate analysis and 1.34 (95% CI, 1.03-1.74; P = 0.02) in propensity score-adjusted analysis. ICU-free days at Day 90 increased from 50 ± 33 in the control phase to 57 ± 29 in the intervention phase (P < 0.01). Mortality at Day 90 was 28.4% in the control phase and 23.5% in the intervention phase (P = 0.22).

CONCLUSIONS

The implementation of an evidence-based extubation readiness bundle was associated with a reduction in the duration of ventilation in patients with brain injury.

Traumatic brain injury in rats induces lung injury and systemic immune suppression

Traumatic brain injury (TBI) is frequently complicated by acute lung injury, which is predictive for poor outcome. However, it is unclear whether lung injury develops independently or as a result of mechanical ventilation after TBI. Further, TBI is strongly associated with the development of pneumonia, suggesting a specific vulnerability for the development of nosocomial infections in the lung after TBI. In this study, we evaluated whether indeed pulmonary injury and immune suppression develop spontaneously in an animal model of mild TBI (mTBI). TBI was induced in male PVG rats by closed-head trauma using a weight-drop device. Subsequently, we evaluated the effects of this on the lungs as well as on the excitability of the systemic immune system. Finally, we performed an experiment in which TBI was followed by induction of pneumonitis and evaluated whether TBI affects the severity of subsequent pneumonitis induced by intratracheal instillation of heat-killed Staphylococcus aureus. mTBI resulted in significant lung injury, as evidenced by pulmonary edema, protein leakage to the alveolar compartment, and increased concentrations of interleukin-1 and -6 in broncho alveolar lavage fluid (all p<0.05 vs. sham-treated animals). Further, after TBI, the release of tumor necrosis factor alpha was decreased when whole blood was stimulated ex vivo (p<0.05 TBI vs. sham), indicating systemic immune suppression. When TBI was followed by pneumonitis, the severity of subsequent pneumonitis was not different in rats previously subjected to TBI or sham treatment (p>0.05), suggesting that systemic immune suppression is not translated toward the pulmonary compartment in this specific model. We here show that during mild experimental TBI, acute pulmonary injury, as well as a decrease in the excitability of the systemic immune system, can be observed.

Appropriateness is critical

Inappropriate empirical antibiotic therapy for severe infections in the intensive care unit is a modifiable prognostic factor that has a great effect on patient outcome and health care resources. Inappropriate treatment is usually associated with microorganisms resistant to the common antibiotics, which must be empirically targeted when risk factors are present. Previous antibiotic exposure, prolonged length of hospital stay, admission category, local susceptibilities, colonization pressure, and the presence of invasive devices increase the likelihood of infection by resistant pathogens. Consideration of issues beyond in vitro susceptibility, such as antibiotic physicochemistry, tissue penetration, and pharmacokinetic/pharmacodynamic-driven dosing, is mandatory for the optimization of antibiotic use.

Lack of impact of selective digestive decontamination on Pseudomonas aeruginosa ventilator-associated pneumonia: benchmarking the evidence base

BACKGROUND

The selective digestive decontamination (SDD) component antibiotics have activity against Pseudomonas aeruginosa, an important ventilator-associated pneumonia (VAP) isolate. Evaluating the relationship between the anti-pseudomonal activity of SDD towards its VAP prevention effect is complicated by postulated indirect effects of SDD mediated in the concurrent control groups. The objective here is to address these effects through a benchmarking analysis of the evidence base.

METHODS

Forty-eight observational studies of VAP incidence and 43 interventional studies of SDD and other methods of VAP prevention were sourced from 10 reviews. The P. aeruginosa isolate proportion (P. aeruginosa-IP) data were summarized by meta-analysis using random effects methods. The mode of VAP diagnosis, proportion of trauma admissions and the intervention method under study were examined in meta-regression models as potential group-level predictors of P. aeruginosa-IP.

RESULTS

The mean P. aeruginosa-IP derived from the observational studies (the benchmark) is 22.3% [95% confidence interval (CI) 19.8%-25.2%] versus 19.6% (95% CI 15.6%-24.4%) and 20.8% (95% CI 14.6%-28.5%) for concurrent control groups and intervention groups of SDD studies, respectively. In the meta-regression models, the proportion of trauma admissions is negatively correlated with P. aeruginosa-IP, whereas membership of neither a concurrent control nor intervention group of an SDD study is negatively correlated.

CONCLUSIONS

There is no evidence for either direct or indirect effects of SDD on P. aeruginosa-IP that could account for the profound effects of SDD on VAP incidence.

The relationship between post-traumatic ventilator-associated pneumonia outcomes and American College of Surgeons trauma centre designation

INTRODUCTION

The relationship between outcomes following severe trauma and American College of Surgeons (ACS) trauma centre designation has been studied. Little is known, however, about the association between ACS level and outcomes associated with ventilator-associated pneumonia (VAP).

METHODS

The National Trauma Databank (NTDB, Version 5.0) was queried to identify adult (age 18)trauma patients who (1) developed VAP and (2) were admitted to either an ACS level I or level II centre.Transfer and burn patients were excluded. Univariate analysis defined differences between patient cohorts. Logistic regression analysis was utilised to identify independent risk factors for mortality.

RESULTS

A total of 3465 patients were identified where 65.6% were admitted to a level I facility and 34.4%to a level II centre. Patients admitted to a level I centre were more likely to have an age > 55 (71.5% vs.66.8%, p = 0.004) and to be hypotensive (SBP < 90) on admission (16.2% vs. 13.6%, p = 0.042). They were also more likely to have a longer duration of mechanical ventilation (18.5 days vs. 16.5 days, p = 0.001),longer hospital LOS (34.2 days vs. 29.6 days, p < 0.001) and a higher rate of early (±7 days) tracheostomy(33.1% vs. 29.1%, p = 0.017). Level I admission was, however, associated with lower mortality rates (10.8%vs. 14.7%, p = 0.001) and a higher likelihood of achieving discharge to home (20.2% vs. 16.1%, p < 0.001).Logistic regression analysis identified admission to a level II facility as an independent risk factor for mortality (OR 1.34, 95% CI 1.08–1.66; p = 0.008) in patients developing post-traumatic VAP.

CONCLUSION

For adults who develop VAP after trauma, admission to a level I facility is associated with improved survival. Further prospective study is needed.

Ventilator-associated pneumonia in trauma patients is associated with lower mortality: results from EU-VAP study

BACKGROUND

Differences in trauma patients developing ventilator-associated pneumonia (VAP) are described regarding etiology and risk factors associated. We aim to describe the differences in outcomes in trauma and nontrauma patients with VAP.

METHODS

A prospective, observational study conducted in 27 intensive care units from nine European countries. We included patients requiring invasive mechanical ventilation for >48 hours who developed VAP. Logistic regression model was used to assess the factors independently associated with mortality in trauma patients with VAP.

RESULTS

A total of 2,436 patients were evaluated; 465 developed VAP and of these 128 (27.5%) were trauma patients. Trauma patients were younger than nontrauma (45.3 ± 19.4 vs. 61.1 ± 16.7, p < 0.0001). Nontrauma had higher simplified acute physiology score II compared with trauma patients (45.5 ± 16.3 vs. 41.1 ± 15.2, p = 0.009). Most prevalent pathogens in trauma patients with early VAP were Enterobacteriaceae spp. (46.9% vs. 27.8%, p = 0.06) followed by methicillin-susceptible Staphylococcus aureus (30.6% vs. 13%, p = 0.03) and then Haemophilus influenzae (14.3% vs. 1.9%, p = 0.02), and the most prevalent pathogen in late VAP was Acinetobacter baumannii (12.2% vs. 44.4%, p < 0.0001). Mortality was higher in nontrauma patients than in trauma patients (42.6% vs. 17.2%, p < 0.001, odds ratio [OR] = 3.55, 95%CI = 2.14-5.88). A logistic regression model adjusted for sex, age, severity of illness at intensive care unit admission, and sepsis-related organ failure assessment score at the day of VAP diagnosis confirmed that trauma was associated with a lower mortality compared with nontrauma patients (odds ratio [OR] = 0.37, 95%CI = 0.21-0.65).

CONCLUSIONS

Trauma patients developing VAP had different demographic characteristics and episodes of etiology. After adjustment for potential confounders, VAP episodes in trauma patients are associated with lower mortality when compared with nontrauma patients.

Utility of ampicillin-sulbactam for empiric treatment of ventilator-associated pneumonia in a trauma population

BACKGROUND

Ampicillin-sulbactam is guideline-recommended treatment for early-onset ventilator-associated pneumonia (VAP). However, intensive care unit clinicians are encountering increasing resistance to ampicillin-sulbactam. We sought to analyze the time period for early-onset VAP in our trauma population by using daily evaluation of resistance to ampicillin-sulbactam.

METHODS

A retrospective cohort study was completed on all mechanically ventilated trauma patients admitted to a rural level-1 trauma center from January 2003 to December 2008 who were diagnosed with VAP. Daily bacterial resistance to ampicillin-sulbactam > 15% was defined as the threshold for early empiric antibiotic failure for the first episode of VAP. A univariate analysis of risk factors for multi-drug resistant pathogens (MDRPs) and comorbidities was completed to assess for predisposing factors for ampicillin-sulbactam resistance.

RESULTS

One hundred sixty-three pathogens were identified in 121 trauma patients diagnosed with VAP. Of these isolates, 71% were gram-negative, 28% were gram-positive, and 1% was fungal. Methicillin-susceptible Staphylococcus aureus (23.9%), H aemophilus influenzae (20.9%), and Pseudomonas aeruginosa (11.7%) were the most common infecting organisms. Daily ampicillin-sulbactam resistance was 40%, 26%, 32%, 43%, 50%, and 60% on days 3 to 7 and ≥ 8 days, respectively. Only the presence of MDRP risk factors (89% vs. 65%, p < 0.01) and hospital LOS (36.8 [22.8-49.0] vs. 25.7 days [19.0-32.5], p < 0.01) was different between ampicillin- sulbactam resistant and ampicillin-sulbactam susceptible VAP groups. On univariate analysis, hospital length of stay >4 days and antibiotic use within 90 days were associated with ampicillin-sulbactam resistant VAP (p < 0.01).

CONCLUSIONS

Ampicillin-sulbactam is not an effective empiric therapy for early-onset VAP in our rural trauma population. The utility of ampicillin-sulbactam should be reviewed at other institutions to assess for appropriate empiricism.

CpG-ODN and MPLA prevent mortality in a murine model of post-hemorrhage-Staphyloccocus aureus pneumonia

Infections are the most frequent cause of complications in trauma patients. Post-traumatic immune suppression (IS) exposes patients to pneumonia (PN). The main pathogen involved in PN is Methicillin Susceptible Staphylococcus aureus (MSSA). Dendritic cells () may be centrally involved in the IS. We assessed the consequences of hemorrhage on pneumonia outcomes and investigated its consequences on DCs functions. A murine model of hemorrhagic shock with a subsequent MSSA pneumonia was used. Hemorrhage decreased the survival rate of infected mice, increased systemic dissemination of sepsis and worsened inflammatory lung lesions. The mRNA expression of Tumor Necrosis Factor-alpha (TNF-α), Interferon-beta (IFN-β) and Interleukin (IL)-12p40 were mitigated for hemorrhaged-mice. The effects of hemorrhage on subsequent PN were apparent on the pDCs phenotype (reduced MHC class II, CD80, and CD86 molecule membrane expression). In addition, hemorrhage dramatically decreased CD8⁺ cDCs- and CD8^- cDCs-induced allogeneic T-cell proliferation during PN compared with mice that did not undergo hemorrhage. In conclusion, hemorrhage increased morbidity and mortality associated with PN; induced severe phenotypic disturbances of the pDCs subset and functional alterations of the cDCs subset. After hemorrhage, a preventive treatment with CpG-ODN or Monophosphoryl Lipid A increased transcriptional activity in DCs (TNF-α, IFN-β and IL-12p40) and decreased mortality of post-hemorrhage MSSA pneumonia.

Staphylococcus aureus nasal colonization and subsequent infection in intensive care unit patients: does methicillin resistance matter?

BACKGROUND

Staphylococcus aureus is an important cause of infection in intensive care unit (ICU) patients. Colonization with methicillin-resistant S. aureus (MRSA) is a risk factor for subsequent S. aureus infection. However, MRSA-colonized patients may have more comorbidities than methicillin-susceptible S. aureus (MSSA)-colonized or noncolonized patients and therefore may be more susceptible to infection on that basis.

OBJECTIVE

To determine whether MRSA-colonized patients who are admitted to medical and surgical ICUs are more likely to develop any S. aureus infection in the ICU, compared with patients colonized with MSSA or not colonized with S. aureus, independent of predisposing patient risk factors.

DESIGN

Prospective cohort study.

SETTING

A 24-bed surgical ICU and a 19-bed medical ICU of a 1,252-bed, academic hospital.

PATIENTS

A total of 9,523 patients for whom nasal swab samples were cultured for S. aureus at ICU admission during the period from December 2002 through August 2007.

METHODS

Patients in the ICU for more than 48 hours were examined for an ICU-acquired S. aureus infection, defined as development of S. aureus infection more than 48 hours after ICU admission.

RESULTS

S. aureus colonization was present at admission for 1,433 (27.8%) of 5,161 patients (674 [47.0%] with MRSA and 759 [53.0%] with MSSA). An ICU-acquired S. aureus infection developed in 113 (2.19%) patients, of whom 75 (66.4%) had an infection due to MRSA. Risk factors associated with an ICU-acquired S. aureus infection included MRSA colonization at admission (adjusted hazard ratio, 4.70 [95% confidence interval, 3.07-7.21]) and MSSA colonization at admission (adjusted hazard ratio, 2.47 [95% confidence interval, 1.52-4.01]).

CONCLUSION

ICU patients colonized with S. aureus were at greater risk of developing a S. aureus infection in the ICU. Even after adjusting for patient-specific risk factors, MRSA-colonized patients were more likely to develop S. aureus infection, compared with MSSA-colonized or noncolonized patients.

Retrospective analysis of the risk factors and pathogens associated with early-onset ventilator-associated pneumonia in surgical-ICU head-trauma patients

BACKGROUND

Early-onset ventilator associated pneumonia (EOVAP) are frequent in head-trauma patients, but specific risk factors are poorly studied in this population.

METHODS

We conducted a retrospective cohort study in a surgical intensive care unit. Consecutive severe head-trauma patients admitted from January 2000 to December 2002 were studied. Microorganisms, and risks factors for EOVAP were analyzed.

RESULTS

During the 3-year period, 161 patients were studied; 21.1% of them developed an EOVAP. On univariate analysis 6 variables were associated with EOVAP: early enteral feeding, barbiturate use, immunosuppression, mean Simplified Acute Physiology Score 2, acute respiratory distress syndrome, and initial neurosurgery procedures. On multivariate analysis, enteral feeding >2000 Kcal before day 5 [odds ratio (OR): 0.33, 95% confidence interval (CI): 0.21-0.85] and initial neurosurgical procedure (OR: 0.36, 95% CI: 0.15-0.89) remained protective factors for EOVAP, whereas immunosuppression (OR: 7.15, 95% CI: 1.66-30.73) and barbiturate use (OR: 2.68, 95% CI: 1.06-6.80) remained risk factors for EOVAP. EOVAP was also significantly associated with a longer duration of mechanical ventilation (14.0 vs. 11.0 d, P=0.024), and a longer sedation duration (8.3 vs. 5.8 d P=0.005). Methicillin-susceptible Staphylococcus aureus was the most common pathogen involved in EOVAP (46%).

CONCLUSIONS

We demonstrate for the first time that early enteral feeding is a protective factor for EOVAP, and this result could have clinical implications for the prevention of EOVAP after traumatic brain injury. This study also confirms that barbiturate use is an important risk factor of EOVAP whereas Methicillin-susceptible S. aureus was found to be the main pathogen involved in EOVAP.