Utility of Gram's stain and efficacy of quantitative cultures for posttraumatic pneumonia: a prospective study

From bedside to bedside: how iterative clinical research influenced the diagnosis and management of pneumonia at the Elvis Presley Trauma Center

Ventilator-associated pneumonia is a well-acknowledged complication after hospitalization for injury or surgical emergency. The contribution to the literature on this topic by Dr Timothy Fabian and the Memphis group at the Elvis Presley Trauma Center resulted in the contemporary recognition that the diagnosis and management of pneumonia is an essential component of surgical critical care. During three decades, the Memphis group, under Dr Fabian's leadership, performed numerous clinical studies that led to the publication of over 40 articles concerning the epidemiology, diagnosis, and treatment of pneumonia after injury. The purpose of this review is to survey the consecutive studies from Memphis specifically that led to the development of a clinical pathway that has stood the test of time. Examination of the research output during this period provides a case study in how bedside clinical research can inform clinical practice and is a model for applied science in the intensive care unit.

Early pneumonia diagnosis decreases ventilator-associated pneumonia rates in trauma population

BACKGROUND

Ventilator-associated pneumonia (VAP) is a source of morbidity and mortality for trauma patients. Aspiration events are also common because of traumatic brain injury, altered mental status, or facial trauma. In patients requiring mechanical ventilation, early pneumonias (EPs) may be erroneously classified as ventilator associated.

METHODS

A prospective early bronchoscopy protocol was implemented from January 2020 to January 2022. Trauma patients intubated before arrival or within 48 hours of admission underwent bronchoalveolar lavage (BAL) within 24 hours of intubation. Patients with more than 100,000 colony-forming units on BAL were considered to have EP.

RESULTS

A total of 117 patients underwent early BAL. Ninety-three (79.5%) had some growth on BAL with 36 (30.8%) meeting criteria for EP. For the total study population, 29 patients (24.8%) were diagnosed with VAP later in their hospital course, 12 of which had previously been diagnosed with EP. Of EP patients (n = 36), 21 (58.3%) were treated with antibiotics based on clinical signs of infection. Of EP patients who had a later pneumonia diagnosed by BAL (n = 12), seven (58.3%) grew the same organism from their initial BAL. When these patients were excluded from VAP calculation, the rate was reduced by 27.6%. Patients with EP had a higher rate of smoking history (41.7% vs. 19.8%, p < 0.001) compared with patients without EP. There was no difference in median hospital length of stay, intensive care unit length of stay, ventilator days, or mortality between the two cohorts.

CONCLUSION

Early pneumonia is common in trauma patients intubated within the first 48 hours of admission and screening with early BAL identifies patients with aspiration or pretraumatic indicators of pneumonia. Accounting for these patients with early BAL significantly reduces reported VAP rates.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level IV.

The Effect of Lung Lavage Volume Return on the Diagnosis of Ventilator-Associated Pneumonia

BACKGROUND

Bronchoalveolar lavage (BAL) is a commonly used tool in the diagnosis of ventilator-associated pneumonia (VAP). Previous protocols recommend 30% lavage return, though no studies have investigated this relationship. This study aims to assess the influence of BAL volume return on VAP diagnosis.

MATERIALS AND METHODS

A retrospective review was performed of a prospectively maintained database for BAL performed from January 2015 to January 2016 in the trauma and surgical ICU at a level 1 trauma center. In total, 147 ventilated patients with clinical suspicion for pneumonia underwent 264 BALs. A protocol was used with five aliquots of 20 cc of saline instilled. Quantitative cultures were performed with 10ˆ5 colony-forming organisms as the threshold for VAP diagnosis. BAL was repeated at 6-8 d on 50 patients. Univariate and multivariate regression analyses were performed to investigate the predictors of VAP diagnosis.

RESULTS

Patients with >40% lavage return had increased rates of VAP diagnosis (odds ratio [OR] 2.86, P = 0.002). Increasing volume return also trended toward a lower false-negative rate. Temperature, leukocytosis, and X-ray infiltrate were not associated with increased VAP diagnosis. Concurrent antibiotic therapy at the time of BAL predicted decreased VAP diagnosis (OR 0.58, P = 0.04). On multivariable analysis, only >40% return remained associated with increased rate of VAP diagnosis (OR 4.00, P = 0.004).

CONCLUSIONS

This study found that >40% lavage volume return was associated with increased VAP diagnosis. Clinicians should consider the reliability of a negative BAL if clinical suspicion of VAP is high and lavage return is <40%. Additional investigation is needed to further elucidate this association.

Use of Aerosolized Antibiotics in Gram-Negative Ventilator-Associated Pneumonia in Trauma Patients

Ventilator-associated pneumonia (VAP) is associated with significant morbidity (ventilator days, ICU days, and cost) and mortality increase in trauma patients. Multidrug-resistant strains of causative VAP pathogens are becoming increasingly common. Aerosolized antibiotics achieve high alveolar concentrations and provide valuable adjuncts in the treatment of VAP. This study examined the impact of aerosolized antibiotics in the treatment of VAP in trauma patients. Patients with either Acinetobacter baumannii or Pseudomonas aeruginosa VAP over 10 years treated with aerosolized antibiotics (cases) were stratified by age, severity of shock, and injury severity. A frequency-matched (by causative pathogen) control group treated without aerosolized antibiotics was used for comparison. Multivariable logistic regression was used to identify predictors for the use of aerosolized antibiotics. One hundred twenty VAP episodes were identified in 100 patients. Microbiologic resolution was achieved in all patients treated with aerosolized antibiotics. There was no difference in mortality (14.5% vs 15.7%, P = 0.87) and no antibiotic-related complications in either group. Multivariable logistic regression identified VAP persistence and relapse as independent predictors for the use of aerosolized antibiotics. Combined with systemic therapy, aerosolized antibiotics broaden the spectrum of therapy. They are valuable adjuncts with minimal risk of antibiotic resistance and/or systemic complications.

Treatment of Achromobacter Ventilator-Associated Pneumonia in Critically Ill Trauma Patients

BACKGROUND

Achromobacter sp are nonfermenting Gram-negative bacilli (NFGNB) that rarely cause severe infections, including ventilator-associated pneumonia (VAP). Data on the treatment of Achromobacter pneumonia are very limited, and the organism has been associated with a high mortality rate. Thus, more data are needed on treating this organism.

OBJECTIVE

To evaluate the treatment of Achromobacter VAP in critically ill trauma patients.

METHODS

This retrospective, observational study evaluated critically ill trauma patients who developed Achromobacter VAP. A previously published pathway for the diagnosis and management of VAP was used according to routine patient care. This included the use of quantitative bronchoscopic bronchoalveolar lavage cultures to definitively diagnose VAP.

RESULTS

A total of 37 episodes of Achromobacter VAP occurred in 34 trauma intensive care unit patients over a 15-year period. The most commonly used definitive antibiotics were imipenem/cilastatin, cefepime, or trimethoprim/sulfamethoxazole. The primary outcome of clinical success was achieved in 32 of 37 episodes (87%). This is similar to previous studies of other NFGNB VAP (eg, Pseudomonas, Acinetobacter) from the study center. Microbiological success was seen in 21 of 28 episodes (75%), and VAP-related mortality was 9% (3 of 34 patients).

CONCLUSIONS

Achromobacter is a rare but potentially serious cause of VAP in critically ill patients. In this study, there was an acceptable success rate compared with other causes of NFGNB VAP in this patient population.

Diagnostic values of CD64, C-reactive protein and procalcitonin in ventilator-associated pneumonia in adult trauma patients: a pilot study

BACKGROUND

Ventilator-associated pneumonia (VAP) is one of the most common nosocomial infections; however, its diagnosis remains difficult to establish in the critical care setting. We investigated the potential role of neutrophil CD64 (nCD64) expression as an early marker for the diagnosis of VAP.

METHODS

Forty-nine consecutive patients with clinically suspected VAP were prospectively included in a single-center study. The levels of nCD64, C-reactive protein (CRP), and serum procalcitonin (PCT) were analyzed for diagnostic evaluation at the time of intubation (baseline), at day 0 (time of diagnosis), and at day 3. The receiver operating characteristic curves were analyzed to identify the ideal cutoff values.

RESULTS

VAP was confirmed in 36 of 49 cases. In patients with and without VAP, the median levels (interquartile range, IQR) of nCD64 did not differ either at baseline [2.4 (IQR, 1.8-3.1) and 2.6 (IQR, 2.3-3.2), respectively; p=0.3] or at day 0 [2 (IQR, 2.5-3.0) and 2.6 (IQR, 2.4-2.9), respectively; p=0.8]. CRP showed the largest area under the curve (AUC) at day 3. The optimum cutoff value for CRP according to the maximum Youden index was 133 mg/dL. This cutoff value had 69% sensitivity and 76% specificity for predicting VAP; the AUC was 0.73 (95% CI, 0.59-0.85). The nCD64 and PCT values could not discriminate between the VAP and non-VAP groups either at day 0 or day 3.

CONCLUSIONS

The results of this pilot study suggest that neutrophil CD64 measurement has a poor role in facilitating the diagnosis of VAP and thus may not be practically recommended to guide the administration of antibiotics when VAP is suspected.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

Adherence to an established diagnostic threshold for ventilator-associated pneumonia contributes to low false-negative rates in trauma patients

BACKGROUND

The diagnosis of ventilator-associated pneumonia (VAP) in our institution has followed an established diagnostic threshold (DT) of equal to or greater than 10 colony-forming units (CFU) per milliliter on bronchoalveolar lavage (BAL) based on our previous study (PS). Because mortality from VAP is related to treatment delay, some have advocated a lower DT. The purpose of the current study (CS) was to evaluate the impact of adherence to this DT for VAP on false-negative (FN) rates and mortality in trauma patients.

METHODS

Consecutive patients over 9 years with VAP (defined as ≥10 CFU/mL in the BAL effluent) subsequent to the PS were identified. Data regarding each BAL performed and the colony counts of each organism identified were recorded. An FN BAL result was defined as any patient who had less than 10 CFU/mL and developed VAP with the same organism up to 7 days after the previous culture. The CS was then compared with the PS.

RESULTS

Over 9 years, 1,679 patients underwent 3,202 BALs. Of these, 79% were male, 88% experienced blunt injury, mean age and Injury Severity Score (ISS) were 44 years and 31, respectively. Overall, there were 73 FN BAL results (2.3%) in the CS compared with 3% in the PS (p = 0.092). In those patients with 10 organisms, the FN rate was reduced (7.5% vs. 11%, p = 0.045), and mortality was unchanged (5.4% vs. 8.3%, p = 0.361) in the CS compared with the PS. The use of the threshold equal to or greater than 10 resulted in a cumulative reduction in antibiotic charges of $1.57 million.

CONCLUSION

Continued adherence to the diagnostic threshold of equal to or greater than 10 for quantitative BAL in trauma patients has maintained a low incidence of FN BALs and reduced patient charges without impacting mortality. The purported benefit of a lower threshold is not supported. In addition, the potential sequelae of increased resistant organisms, antibiotic-related complications, and costs associated with prolonged unnecessary antibiotic exposure are minimized.

LEVEL OF EVIDENCE

Prognostic study, level III.

Impact of pathogen-directed antimicrobial therapy for ventilator-associated pneumonia in trauma patients on charges and recurrence

BACKGROUND

Ventilator-associated pneumonia (VAP) represents one of the driving forces behind antibiotic use in the ICU. In a previous study, we established a defined algorithm for treatment of hospital-acquired VAP dictated by the causative pathogen. The purpose of the current study was to evaluate the impact of this algorithm for hospital-acquired VAP on recurrence and charges in trauma patients.

STUDY DESIGN

Patients with VAP secondary to MRSA, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, or Enterobacteriaceae during 5 years subsequent to the previous study were evaluated. All VAP were diagnosed using quantitative cultures of the bronchoalveolar lavage effluent. Duration of antimicrobial therapy was dictated by the causative pathogen. If microbiologic resolution, defined as <10(3) colony-forming units/mL, was achieved, therapy was stopped by day 10. The remainder received 14 days of therapy. Recurrence was defined as >10(5) colony-forming units/mL on subsequent bronchoalveolar lavage performed within 2 weeks after completion of appropriate therapy.

RESULTS

Five hundred and twenty-nine VAP episodes were identified in 381 patients. Overall recurrence was unchanged compared with the previous study (1.5% vs 2%; p = 0.3). There was a decrease in the number of bronchoalveolar lavages performed per patient compared with the previous study (1.6 vs 2.3; p = 0.24) and a reduction of 4.8 antibiotic days per VAP episode compared with the previous study. Both changes resulted in a cumulative reduction of $3,535.04 per patient, for a savings of $1.35 million during the study period.

CONCLUSIONS

Hospital-acquired VAP can be managed effectively by a defined course of therapy dictated by the causative pathogen. Adherence to an established algorithm simplified the management of VAP and contributed to a cumulative reduction in patient charges without impacting recurrence.

Use of rapid diagnostic techniques in ICU patients with infections

Background

Infection is a common complication seen in ICU patients. Given the correlation between infection and mortality in these patients, a rapid etiological diagnosis and the determination of antimicrobial resistance markers are of paramount importance, especially in view of today's globally spread of multi drug resistance microorganisms. This paper reviews some of the rapid diagnostic techniques available for ICU patients with infections.

Methods

A narrative review of recent peer-reviewed literature (published between 1995 and 2014) was performed using as the search terms: Intensive care medicine, Microbiological techniques, Clinical laboratory techniques, Diagnosis, and Rapid diagnosis, with no language restrictions.

Results

The most developed microbiology fields for a rapid diagnosis of infection in critically ill patients are those related to the diagnosis of bloodstream infection, pneumonia -both ventilator associated and non-ventilator associated-, urinary tract infection, skin and soft tissue infections, viral infections and tuberculosis.

Conclusions

New developments in the field of microbiology have served to shorten turnaround times and optimize the treatment of many types of infection. Although there are still some unresolved limitations of the use of molecular techniques for a rapid diagnosis of infection in the ICU patient, this approach holds much promise for the future.

National Trauma Institute prospective evaluation of the ventilator bundle in trauma patients: does it really work?

BACKGROUND

Since its introduction by the Institute for Healthcare Improvement, the ventilator bundle (VB) has been credited with a reduction in ventilator-associated pneumonia (VAP). The VB consists of stress ulcer prophylaxis, deep venous thrombosis prophylaxis, head-of-bed elevation, and daily sedation vacation with weaning assessment. While there is little compelling evidence that the VB is effective, it has been widely accepted. The Centers for Medical and Medicaid Services has suggested that VAP should be a "never event" and may reduce payment to providers. To provide evidence of its efficacy, the National Trauma Institute organized a prospective multi-institutional trial to evaluate the utility of the VB.

METHODS

This prospective observational multi-institutional study included six Level I trauma centers. Entry criteria required at least 2 days of mechanical ventilation of trauma patients in an intensive care unit (ICU). Patients were followed up daily in the ICU until the development of VAP, ICU discharge, or death. Compliance for each VB component was recorded daily, along with patient risk factors and injury specifics. Primary outcomes were VAP and death. VB compliance was analyzed as a time-dependent covariate using Cox regression as it relates to outcomes.

RESULTS

A total 630 patients were enrolled; 72% were male, predominately with blunt injury; and mean age, Injury Severity Score (ISS), and 24-hour Glasgow Coma Scale (GCS) score were 47, 24, and 8.7, respectively. VAP occurred in 36%; mortality was 15%. Logistic regression identified male sex and pulmonary contusion as independent predictors of VAP and age, ISS, and 24-hour Acute Physiology and Chronic Health Evaluation as independent predictors of death. Cox regression analysis demonstrated that the VB, as a time-dependent covariate, was not associated with VAP prevention.

CONCLUSION

In trauma patients, VAP is independently associated with male sex and chest injury severity and not the VB. While quality improvement activities should continue efforts toward VAP prevention, the Institute for Healthcare Improvement VB is not the answer. Financial penalties for VAP and VB noncompliance are not warranted.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Bilateral versus unilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) complicates the clinical course of critically injured intubated patients. Bronchoscopic bronchoalveolar lavage (BAL) represents an invasive and accurate means of VAP diagnosis. Unilateral and blinded techniques offer less invasive alternatives to bronchoscopic BAL. This study evaluated clinical criteria as well as unilateral directed versus bilateral BAL for VAP diagnosis.

METHODS

A retrospective chart review of 113 consecutive intubated trauma patients with clinically suspected VAP undergoing unilateral versus bilateral BAL was performed with comparison of positive culture results (>10(4) colony-forming units [CFU]/mL). Culture results were compared with chest radiograph (CXR) infiltrates and white blood cell (WBC) count elevation.

RESULTS

Bilateral BAL was more likely to be positive than unilateral BAL (50.4% vs. 25.5%). In 37.1% of bilateral BALs, there was discordance between the sides of positivity or the bacteria isolated. A CXR infiltrate and WBC count elevation did not predict positive BAL.

CONCLUSIONS

Clinical indicators of VAP are inaccurate, and bilateral bronchoscopic BAL is more likely than unilateral BAL to provide a positive sample in intubated trauma patients. Techniques that do not sample both lungs reliably should be avoided for diagnosis in this patient population.

Estudo bacteriológico do lavado broncoalveolar na gestão de antibióticos na pneumonia associada à ventilação mecânica de pacientes em unidades de terapia intensiva cirúrgica

OBJETIVO: determinar a correlação da coloração de Gram com o resultado final das culturas de LBA em pacientes cirúrgicos sob ventilação mecânica com PAV clínica. MÉTODOS: Estudo retrospectivo de 252 amostras de lavado broncoalveolar em pacientes com clínica de pneumonia associada à ventilação mecânica com trauma ou cuidados de pós-operatório. As amostras de coloração de Gram foram classificadas como cocos Gram-positivos e bacilos Gram-negativos, todos os outros resultados foram excluídos. Culturas de lavado broncoalveolar foram comparadas aos resultados da coloração de Gram. RESULTADOS: A correlação entre a coloração de Gram e a cultura do lavado broncoalveolar apresentou índice kappa de 0,27. A sensibilidade da coloração de Gram foi 53,9% e a especificidade de 80,6%. Considerando a identificação de cocos Gram-positivos comparada com os outros resultados (negativos e bacilos Gram-negativos), o valor preditivo negativo foi 94,8%. Na avaliação de bacilos Gram-negativos comparada com os outros resultados (negativos e cocos Gram-positivos), a sensibilidade foi 27,1% e a especificidade foi 95,4%. CONCLUSÃO: O valor preditivo negativo para cocos Gram-positivos parece ser aceitável, mas a sensibilidade da coloração de Gram na etiologia de pneumonia associada à ventilação mecânica não permite prever qual é o micro-organismo antes da cultura.

Treatment of methicillin-resistant Staphylococcus aureus ventilator-associated pneumonia with high-dose vancomycin or linezolid

BACKGROUND

The purpose of this study was to determine the clinical cure rate of high-dose vancomycin for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) ventilator-associated pneumonia (VAP) in critically ill trauma patients. Recent trials suggest that a traditional dose of 1 g q12 hours results in unacceptable cure rates for MRSA VAP. Thus, more aggressive vancomycin dosing has the potential to improve efficacy. Based on pharmacokinetic principles, the goal initial dose at the study center has been 20 mg/kg q12 hours or q8 hours since the 1990s.

METHODS

All patients admitted to the trauma intensive care unit from 1997 to 2008 diagnosed with MRSA VAP were retrospectively reviewed. Diagnosis required bacterial growth ≥ 100,000 colony forming units/mL from a bronchoscopic bronchoalveolar lavage, new or changing infiltrate, plus at least two of the following: fever, leukocytosis or leukopenia, or purulent sputum.

RESULTS

Overall, 125 patients with 141 episodes of MRSA VAP were identified. Mean age was 47 years ± 21 years, median Injury Severity Score was 29 (22-43), 70% of patients were male, and the mean length of intensive care unit stay was 38 days ± 35 days. The mean initial vancomycin dose was 18.1 mg/kg/dose with a mean duration of therapy of 11 days. Clinical success was achieved in 88% (125 of 131) of episodes, with microbiological success in 89% (66 of 74) of episodes with a follow-up bronchoscopic bronchoalveolar lavage. Overall mortality was 20% (25 of 125), with death due to VAP in 12 of 25 deaths. Mean initial vancomycin trough concentrations were 10.6 mg/L in the clinical success group and 13.3 mg/L in the clinical failure group (p = not significant).

CONCLUSIONS

High-dose vancomycin provided an acceptable cure rate for MRSA VAP in critically ill trauma patients.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Developing a gene expression model for predicting ventilator-associated pneumonia in trauma patients: a pilot study

Background

Ventilator-associated pneumonia (VAP) carries significant mortality and morbidity. Predicting which patients will become infected could lead to measures to reduce the incidence of VAP.

Methodology/Principal Findings

The goal was to begin constructing a model for VAP prediction in critically-injured trauma patients, and to identify differentially expressed genes in patients who go on to develop VAP compared to similar patients who do not. Gene expression profiles of lipopolysaccharide stimulated blood cells in critically injured trauma patients that went on to develop ventilator-associated pneumonia (n = 10) was compared to those that never developed the infection (n = 10). Eight hundred and ten genes were differentially expressed between the two groups (ANOVA, P<0.05) and further analyzed by hierarchical clustering and principal component analysis. Functional analysis using Gene Ontology and KEGG classifications revealed enrichment in multiple categories including regulation of protein translation, regulation of protease activity, and response to bacterial infection. A logistic regression model was developed that accurately predicted critically-injured trauma patients that went on to develop VAP (VAP+) and those that did not (VAP−). Five genes (PIK3R3, ATP2A1, PI3, ADAM8, and HCN4) were common to all top 20 significant genes that were identified from all independent training sets in the cross validation. Hierarchical clustering using these five genes accurately categorized 95% of patients and PCA visualization demonstrated two discernable groups (VAP+ and VAP−).

Conclusions/Significance

A logistic regression model using cross-validation accurately predicted patients that developed ventilator-associated pneumonia and should now be tested on a larger cohort of trauma patients.

Risk stratification for the development of a subsequent pneumonia after a nondiagnostic bronchoalveolar lavage

BACKGROUND

Broncho-alveolar lavage (BAL) is an invasive bedside procedure to define type and concentration of pathologic organisms causing ventilator associated pneumonia (VAP). We evaluated if the absence of pathogens on final results represented a lavage aspect of the BAL as a therapeutic procedure to eliminate organisms.

METHODS

BAL results collected from 2008 to 2009 were stratified as positive (POS) ≥ 100,000 cfu), indeterminate (INT) ≤ 100,000 cfu pathologic organisms, or negative defined as mixed flora (MF) or sterile (STR). The INT, MF, and STR results were assessed by incidence of a subsequent POS sample.

RESULTS

Nine-hundred forty-nine BALs performed on 490 SICU patients were interpreted as POS in 227 patients (46%). 237 non- POS patients needed a subsequent BAL. Any pathogen on the first BAL (INT group) indicates a high likelihood for subsequent BAL which will be POS. Monthly cumulative sum analysis (CUSUM) of yield was unable to identify any specific period in which BAL performance varied from trend.

CONCLUSION

MF and STR represent adequate sampling of secretions that are clinically benign. Any pathogen, regardless of concentration, should be considered a biomarker for future pneumonia. CUSUM analysis suggest better training in timing and indication may decrease unnecessary procedures yielding negative results.

The diagnostic dilemma of ventilator-associated pneumonia in critically ill children

OBJECTIVE

A review of the existing literature on ventilator-associated pneumonia in children with emphasis on problems in diagnosis.

DATA SOURCES

A systematic literature review from 1947 to 2010 using Ovid MEDLINE, PubMed, Cochrane Central Register of Controlled Trials, and ISI Web of Science using key words "ventilator associated pneumonia" and "children." Where pediatric data were lacking, appropriate adult studies were reviewed and similarly referenced.

STUDY SELECTION

Two hundred sixty-two pediatric articles were reviewed and data from 48 studies selected. Data from 61 adult articles were also included in this review.

DATA EXTRACTION AND SYNTHESIS

Ventilator-associated pneumonia is the second most common nosocomial infection and the most common reason for antibiotic use in the pediatric intensive care unit. Attributable mortality is uncertain but ventilator-associated pneumonia is associated with significant morbidity and cost. Diagnosis is problematic in that clinical, radiologic, and microbiologic criteria lack sensitivity and specificity relative to autopsy histopathology and culture. Qualitative tracheal aspirate cultures are commonly used in diagnosis but lack specificity. Quantitative tracheal aspirate cultures have sensitivity (31-69%) and specificity (55-100%) comparable to bronchoalveolar lavage (11-90% and 43-100%, respectively) but concordance for the same bacterial species when compared with autopsy lung culture was better for bronchoalveolar lavage (52-90% vs. 50-76% for quantitative tracheal aspirate). Staphylococcus aureus and Pseudomonas species are the most common organisms, but microbiologic flora change over time and with antibiotic use. Initial antibiotics should offer broad-spectrum coverage but should be narrowed as clinical response and cultures dictate.

CONCLUSIONS

Ventilator-associated pneumonia is an important nosocomial infection in the pediatric intensive care unit. Conclusions regarding epidemiology, treatment, and outcomes are greatly hampered by the inadequacies of current diagnostic methods. We recommend a more rigorous approach to diagnosis by using the Centers for Disease Control and Prevention algorithm. Given that ventilator-associated pneumonia is the most common reason for antibiotic use in the pediatric intensive care unit, more systematic studies are sorely needed.

Bronchoalveolar Lavage in the Diagnosis of Ventilator-Associated Pneumonia: To Quantitate or Not, That is the Question

Quantitative bronchoalveolar lavage (BAL) is used to diagnose ventilator-associated pneumonia (VAP). We prospectively compared semiquantitative (SQ) and quantitative (Qu) culture of BAL for VAP diagnosis. Ventilated patients suspected of VAP underwent bronchoscopic BAL. BAL fluid was examined by both Qu (colony-forming units [CFUs]/mL) and SQ culture (none, sparse, moderate, or heavy) and results were compared. VAP was defined as 105 CFU/mL or greater on Qu culture. Over 36 months, 319 BALs were performed. Sixty-three of 319 (20%) showed diagnostic growth by Qu culture identifying a total of 81 organisms causing VAP. All 63 specimens showed growth of some organism(s) on SQ culture with 79 of 81 causative organisms identified and two ( Pseudomonas, one; Corynebacterium, one) not identified. The remaining 256 specimens did not meet the threshold for VAP by the Qu method. Among these, 79 did not show any growth on SQ culture. Among the 240 specimens showing some growth on SQ culture, a total of 384 organisms were identified. VAP rates in relation to strength of growth on SQ culture were: sparse, 10 of 140 (7%); moderate, 24 of 147 (16%); and heavy, 45 of 97 (46%). Sensitivity (Sn), specificity (Sp), positive (PPV), and negative (NPV) predictive values of SQ culture of BAL fluid for the diagnosis of VAP were 97, 21, 21, and 97 per cent, respectively. Nonquantitative culture of BAL fluid is fairly accurate in ruling out VAP (high Sn and NPV). It however has poor Sp and PPV and using this method will lead to unnecessary antimicrobial use with its attendant complications of toxicity, cost, and resistance.

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.

Mixed Flora: Indication for Therapy or Early Warning Sign?

“Mixed flora” is a commonly returned result yielding not in either indication for therapy or identification of potential causative organisms. We sought to determine whether mixed flora (MF) was in fact a harbinger of impending pneumonia or a benign result that could be therapeutically ignored. Bronchoalveolar lavage (BAL) results of injured adults undergoing mechanical ventilation in a trauma intensive care unit were stratified by identified organisms and by colony counts. The incidence of mixed flora as a component of the specimen report was compared for diagnostic (greater than 105 colony forming units/mL) versus nondiagnostic results using χ2 accepting P < 0.05 as significant. Nondiagnostic specimens were then stratified as MF only or MF and other identified pathogenic organisms. This group was further evaluated to determine the use of antibiotic therapy and development of pneumonia. Finally, patients with nondiagnostic reports and subsequent BAL were analyzed to determine specific species if subsequent BAL were required or if later pneumonia occurred. During 2007, 159 BALs were performed on injured patients of which 93 were diagnostic for pneumonia, whereas 66 were nondiagnostic. Of the diagnostic specimens, 15 (16%) included mixed flora. Of the 66 nondiagnostic specimens, 39 (59%) contained mixed flora. Nine (60%) of the 15 with diagnostic mixed flora were started on antibiotic therapy for an average of 6.2 days. The remaining 39 (82%) patients with mixed flora received no antibiotic therapy and never developed pneumonia. These data demonstrate that in the absence of diagnostic threshold of an identifiable pathogenic organism, therapy for pneumonia should not be instituted or continued.

The pathogen of ventilator-associated pneumonia does not influence the mortality rate of surgical intensive care unit patients treated with a rotational antibiotic system

BACKGROUND

Ventilator-associated pneumonia (VAP) is one of the leading causes of morbidity in critically ill surgical patients. Certain pathogens (e.g., methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa) have been associated with an excess mortality rate from sepsis in several studies, but not in the surgical setting specifically or when protocol-driven antibiotic therapy is administered.

PURPOSE

We sought to determine which factors and, in particular, whether the individual pathogen affected the mortality rate in our surgical intensive care unit (ICU), where a rotational antibiotic system has been employed continuously since 1997. We hypothesized that the type of pathogen and illness severity were the primary influences on the mortality rate of patients with VAP.

METHODS

A total of 198 consecutive patients from a university surgical ICU, with clinical signs of VAP confirmed by quantified isolation of significant numbers of a pathogen (> or =10(4) colony-forming units [cfu]/mL) from bronchoalveolar (BAL) fluid obtained by fiberoptic bronchoscopy, were identified prospectively from January 2001 to November 2004. The data collected were age, sex, Acute Physiology and Chronic Health Evaluation (APACHE) III score, multiple organ dysfunction score, unit day of diagnosis, time (h) to antibiotic administration (TTA), appropriateness of initial therapy (AIT), unit and hospital length of stay, and mortality rate. Pathogens were classified as non-lactose-fermenting gram-negative bacilli (NGNB), lactose-fermenting gram-negative bacilli (LGNB), methicillin-sensitive Staphylococcus aureus, methicillin-resistant S. aureus, yeast, community-acquired pneumonia (e.g., Streptococcus pneumoniae), or other pathogens. Patients with a polymicrobial isolate were placed in the "other" category.

RESULTS

The overall mortality rate was 32.3% vs. 55% as predicted by APACHE III normative data. The overall AIT was 92%. The mortality rate for NGNB infections was 35.6% vs. 29.4% for LGNB infections (p = NS). By logistic regression, neither TTA, AIT, nor pathogen influenced the mortality rate.

CONCLUSIONS

The type of pathogen does not influence death in surgical ICU patients with VAP diagnosed rigorously and treated by a rotational antibiotic system. The high proportion of AIT as a result of the rotational antibiotic administration system optimizes bacterial killing and negates the impact of bacterial resistance, contributing to better outcomes.

Hospital-acquired pneumonia: pathophysiology, diagnosis, and treatment

Hospital-acquired pneumonia (HAP) is one of the most common causes of nosocomial infection, morbidity, and mortality in hospitalized patients. Many patient- and disease-specific factors contribute to the pathophysiology of HAP, particularly in the surgical population. Risk-factor modification and inpatient prevention strategies can have a significant impact on the incidence of HAP. While the best diagnostic strategy remains a subject of some debate, prompt and appropriate antimicrobial therapy in patients suspected of having HAP has been shown to significantly decrease mortality. Because the pathogens responsible for HAP are frequently more virulent and have greater resistance to commonly used antimicrobials than other pathogens, clinicians must have knowledge of the resistance patterns at their institutions to choose appropriate therapy.

Efficacy of monotherapy in the treatment of Pseudomonas ventilator-associated pneumonia in patients with trauma

BACKGROUND

Controversy persists regarding the optimal treatment regimen for Pseudomonas ventilator-associated pneumonia (VAP). Combination antibiotic therapy is used to broaden the spectrum of activity of empiric treatment and provide synergistic bacteriocidal activity. The relevance of such "synergy" is commonly supposed but poorly supported. The purpose of this study was to evaluate the efficacy of monotherapy in the treatment of Pseudomonas VAP as measured by microbiological resolution.

METHODS

Patients admitted to the trauma intensive care unit during a 36-month period with gram-negative VAP diagnosed on initial bronchoalveolar lavage (BAL) (> or = 10(5) colony forming units [CFU]/mL) were evaluated. All patients received empiric antibiotic monotherapy based on the duration of intensive care unit stay. Patients with Pseudomonas VAP were identified and appropriate monotherapy was selected. Repeat BAL was performed on day 4 of appropriate antibiotic therapy to determine efficacy. Microbiological resolution was defined as < or = 10(3) CFU/mL. Combination therapy with an aminoglycoside was reserved for patients with either persistent positive or increasing colony counts on repeat BAL. Recurrence was defined as > or = 10(5) CFU/mL on subsequent BAL after 2 weeks of appropriate therapy.

RESULTS

One hundred ninety-six patients were identified with late gram-negative VAP. There were 84 patients with Pseudomonas VAP. Monotherapy achieved microbiological resolution in 79 patients (94.1%) with zero recurrence. Thirty-six isolates were completely eradicated at repeat BAL. Five patients (5.9%) required combination therapy to achieve resolution.

CONCLUSIONS

Monotherapy in the treatment of Pseudomonas VAP has an excellent success rate in patients with trauma. Empiric monotherapy therapy should be modified once susceptibility of the microorganism is documented (all isolates were sensitive to cefepime) and antibiotic choice should be based on local patterns of susceptibilities. The routine use of combination therapy for synergy is unnecessary. Combination therapy should be reserved for patients with persistent microbiological evidence of Pseudomonas VAP despite adequate therapy.

Utility of preliminary bronchoalveolar lavage results in suspected ventilator-associated pneumonia

BACKGROUND

More than one half of lower respiratory cultures are negative for ventilator-associated pneumonia (VAP) and final reporting requires 72 hours to 96 hours. A previous retrospective study concluded that preliminary bronchoalveolar lavage (BAL) culture results (pBAL), reported at approximately 24 hours, accurately predicted final BAL culture results (fBAL). Our objective was to verify the predictive value of pBALs for fBALs, and evaluate the use of insignificant (1-99,999 cfu/mL) pBALs for rapid discontinuation of empirical antibiotics.

METHODS

All BALs performed in the intensive care unit (ICU) of the Presley Regional Trauma Center were used to compare pBALs with fBALs. Trauma intensive care unit patients whose antibiotics were discontinued using pBALs (study group), were compared with a historical control group who had their antibiotics discontinued using fBALs.

RESULTS

Preliminary and final results of 474 prospectively collected BALs were compared. Significant pBALs had a positive predictive value of 100%, whereas the negative predictive values of "no growth to date" and insignificant pBALs were 99% and 95%, respectively. Study patients (n = 176) were similar to control patients (n = 112) except for a higher median injury severity score (34 vs. 29; p < 0.001). The median (interquartile range) duration of empirical antibiotic therapy in patients without VAP was shorter for study patients [1.5 (1.25, 2) vs. 3 (3, 4) days, p < 0.001]. Empirical antibiotics were temporarily interrupted in four patients with VAP because of falsely negative pBALs without adverse clinical sequelae.

CONCLUSIONS

Preliminary BALs were highly predictive for final results. Using insignificant pBALs appears to be a safe strategy for promptly discontinuing empirical antibiotics in trauma patients with suspected VAP.

Predictive value of broncho-alveolar lavage fluid Gram's stain in the diagnosis of ventilator-associated pneumonia: a prospective study

BACKGROUND

Quantitative broncho-alveolar lavage (qBAL) is increasingly being used for diagnosing ventilator-associated pneumonia (VAP). The current study prospectively evaluates the accuracy of broncho-alveolar lavage fluid Gram's stain (GS) in predicting both the presence of VAP and the class of causative microorganism in patients suspected of VAP.

METHODS

Patients suspected of VAP in a trauma or surgical intensive care unit underwent bronchoscopic qBAL with GS. Presence and class of organisms seen on GS were correlated respectively with the presence of VAP, as diagnosed by qBAL, and class of causative microorganism. VAP was defined as qBAL >10(5) colony forming units/mL. All data were gathered prospectively.

RESULTS

During a 28-month study period, 229 patients underwent 309 qBALs for suspected VAP. Seventy-one (23%) specimens were positive for VAP (qBAL>10(5) CFU/mL). Fifty-four specimens (77%) had one causative microorganism, 13 (18%) had two, 3 (4%) had three, and 1 (1%) demonstrated four microorganisms giving a total of 93 VAPs. Forty-one (62%) of 66 specimens showing moderate or many microorganisms on GS were positive for VAP. However, 7 (4%) of 167 specimens showing none and 23 (30%) of 76 showing few microorganisms on GS were also positive for VAP. Of the 64 qBAL specimens positive for VAP and where the GS showed microorganisms, 6 (23%) of 26 showing only G+ microorganisms on GS had G- VAP (G- alone, 4; G+ and G-, 2), and 1 (8%) of 12 showing G- microorganisms only had G+ and G- VAP. Of the seven qBAL specimens positive for VAP where the GS did not show microorganisms, one had G+ and six had G- VAP. With the threshold of positivity of GS at more than none, the sensitivity, specificity, positive, and negative predictive values of GS for the presence of VAP were 90%, 67%, 45%, and 96% respectively.

CONCLUSIONS

Broncho-alveolar lavage fluid GS is poor in predicting the presence of VAP and predicting the class of causative microorganism. Using GS to determine necessity of and to select class of antimicrobial therapy will result in delayed or inappropriate VAP therapy or both.

Subthreshold quantitative bronchoalveolar lavage: clinical and therapeutic implications

BACKGROUND

Quantitative bronchoalveolar lavage (qBAL) is used for accurate diagnosis of ventilator-associated pneumonia (VAP). The current study aims at defining the incidence, outcomes and therapeutic implications of false-negative (FN) qBAL.

METHODS

Ventilated trauma, surgery, and burn, patients suspected of VAP underwent bronchoscopic qBAL. VAP was defined as qBAL with >10(5) CFU/mL (threshold). To identify FN BALs, blood cultures drawn concomitant with BAL (+/-5 days of BAL) were analyzed. qBAL specimens growing <10(5) CFU/mL (subthreshold) with blood culture identifying the same organism, without any other source, were classified as FN.

RESULTS

Over 39 months, 246 patients underwent 365 qBALs. Ninety-one specimens had no growth and 274 specimens grew 433 organisms--100 at threshold and 333 at subthreshold strength. Sixteen percent of threshold and 11% of subthreshold organisms were associated with bacteremia. Rates of bacteremia were similar across strengths of growth. Bacteremia at all strengths of growth was more common with Staphylococcal species (methicillin sensitive and resistant) and for hospital-acquired gram-negatives. Rates of bacteremia at all strengths of growth were significantly higher after the first week of hospitalization. Bacteremia worsened outcomes in both threshold group (higher mortality, p < 0.05) and subthreshold group (longer lengths of stay, p < 0.05).

CONCLUSIONS

qBAL has 11% FN rate as measured by blood stream invasion. Propensity of blood stream invasion is related to species of organism (Staphylococcal species and hospital-acquired gram-negatives) and duration of hospitalization, but not to strength of growth. Isolation of these organisms in BAL, at any strength, after the first week should prompt strong consideration for antimicrobial therapy.

Utility of Gram stain in the clinical management of suspected ventilator-associated pneumonia. Secondary analysis of a multicenter randomized trial

PURPOSE

Gram stains of endotracheal aspirates (EA) and bronchoalveolar lavages (BAL) may guide empiric antibiotic therapy in critically ill patients with suspected ventilator-associated pneumonia (VAP). Previous studies differ regarding the ability of the Gram stain to predict final culture results. The aim of the present study was to evaluate the relationship between EA or BAL Gram stains and final culture results in intensive care unit patients with a suspected VAP.

MATERIAL AND METHODS

We retrospectively analyzed data from the Canadian multicenter VAP study to correlate EA or BAL Gram stain and final culture results. We categorized Gram stains as Gram positive (GP) and Gram negative (GN) if any GP or GN organisms respectively were seen on staining. Cultures were considered "positive" if they yielded pathogenic organisms on final results.

RESULTS

Seven hundred forty patients were enrolled in the study; 35 did not have a Gram stain done leaving 350 BALs and 355 EAs from 705 patients. Pooling BAL and EA results, we found the overall agreement between Gram stain class and pathogenic bacteria culture results to be poor (kappa = 0.36; 95% CI, 0.31-0.40). Among specimens with Gram stains showing no organisms, 99 (30%) of 331 grew pathogenic organisms. Among specimens with Gram stains showing no GN organisms, 113 (25%) of 452 grew pathogenic GN organisms. Among specimens with Gram stains showing no GP organisms, 45 (11%) of 428 grew pathogenic GP organisms.

CONCLUSIONS

Gram stains performed for clinically suspected VAP poorly predict the final culture result and thus have a limited role in guiding initial empiric antibiotic therapy in such patients.

Reduction in Inadequate Empiric Antibiotic Therapy for Ventilator-Associated Pneumonia: Impact of a Unit-Specific Treatment Pathway

Empiric antibiotic therapy is routinely initiated for patients with presumed ventilator-associated pneumonia (VAP). Reported mortality rates for inadequate empiric antibiotic therapy (IEAT) for VAP range from 45 to 91 per cent. The purpose of this study was to determine the effect of a unit-specific pathway for the empiric management of VAP on reducing IEAT episodes and improving outcomes in trauma patients. Patients admitted with VAP over 36-months were identified and stratified by gender, age, severity of shock, and injury severity. Outcomes included number of IEAT episodes, ventilator days, intensive care unit days, hospital days, and mortality. Three hundred and ninety-three patients with 668 VAP episodes were identified. There were 144 (22%) IEAT episodes: significantly reduced compared with our previous study (39%) ( P < 0.001). Patients were classified by number of IEAT episodes: 0 (n = 271), 1 (n = 98) and ≥ 2 (n = 24). Mortality was 12 per cent, 13 per cent, and 38 per cent ( P < 0.001), respectively. Multivariable logistic regression identified multiple IEAT episodes as an independent predictor of mortality (odds ratio = 4.7; 95% confidence interval: 1.684–13.162). Multiple IEAT episodes were also associated with prolonged mechanical ventilation and intensive care unit stay ( P < 0.001). Trauma patients with multiple IEAT episodes for VAP have increased morbidity and mortality. Adherence to a unit-specific pathway for the empiric management of VAP reduces multiple IEAT episodes. By limiting IEAT episodes, resource utilization and hospital mortality are significantly decreased.

Impact of gender on outcomes after blunt injury: a definitive analysis of more than 36,000 trauma patients

BACKGROUND

The concept that premenopausal female patients are more resistant to shock than male patients has been shown in numerous preclinical models. The more relevant effect of gender on clinically important outcomes after trauma is less clear. Clinical studies have been conflicting, both supporting and refuting the protective effects of gender on outcomes, primarily because of limitations in sample size and patient stratification. In an attempt to resolve this ongoing dispute, we evaluated the effect of gender on various outcomes in the largest single institutional series of trauma patients reported in the literature after blunt injury.

STUDY DESIGN

All patients sustaining blunt trauma during a 10-year period were identified from the trauma registry and stratified by gender, age, and severity of shock and injury. Outcomes included ventilator-associated pneumonia, ARDS, bacteremia, ventilator days, ICU days, hospital length of stay, and mortality. Multivariable logistic regression was performed to determine whether gender was an independent predictor of mortality, morbidity, or both.

RESULTS

There were 36,010 patients identified; 304 died in the resuscitation area, leaving 24,331 men and 11,375 women for analysis. Logistic regression identified gender as an independent predictor of morbidity but failed to show gender as an independent predictor of early (48-hour and 7-day) and overall mortality.

CONCLUSIONS

Multivariable logistic regression analysis of a large trauma cohort definitively establishes that gender is not independently associated with mortality after blunt trauma in humans. In contrast, male gender was shown to be associated with increased morbidity. Unlike rodent studies, gender alone offers no survival advantage in humans after blunt trauma.

Repeat bronchoalveolar lavage to guide antibiotic duration for ventilator-associated pneumonia

BACKGROUND

Using an arbitrary day cutoff or clinical signs to decide the duration of antibiotic therapy for ventilator-associated pneumonia (VAP) may be suboptimal for some patients. We sought to determine whether antibiotic duration for VAP can be safely abbreviated in trauma patients using repeat bronchoalveolar lavage (BAL).

METHODS

This was an observational case-controlled pilot study. Fifty-two patients were treated for VAP using a repeat BAL clinical pathway. Definitive antibiotic therapy for VAP was discontinued if pathogen growth was <10,000 colony forming units/mL on repeat BAL performed on day 4 of antibiotic therapy (responder), otherwise therapy was continued per managing team. A matched control group of 52 VAP patients treated before (immediately consecutive) the pathway was used for comparison.

RESULTS

Antibiotic duration in pathway patients was shorter than control patients (9.8 days +/- 3.8 days vs. 16.7 days +/- 7.4 days; p < 0.001), including nonfermenting gram-negative bacilli VAP (10.7 days +/- 4.1 days vs. 14.4 days +/- 4.2 days; p < 0.001). There were no differences in pneumonia relapse, mechanical ventilator-free intensive care unit (ICU) days, ICU-free hospital days, or mortality. Of study group isolates, 86 (82.7%) responded on repeat BAL and were treated for 8.8 days +/- 3.3 days. Of these without concomitant infections (n = 65), antibiotic duration was 7.3 days +/- 1.2 days compared with 14.4 days +/- 2.6 days for nonresponding isolates (n = 18) (p < 0.001).

CONCLUSIONS

Repeat BAL decreased the duration of antibiotic therapy for VAP in trauma patients. More adequately powered investigations are needed to appropriately determine the effects of this strategy on patient outcome.

Utility of bilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia in critically ill surgical patients

BACKGROUND

Bronchoalveolar lavage (BAL) is recommended to facilitate the diagnosis of ventilator-associated pneumonia (VAP). It is unclear if bilateral sampling improves the accuracy of BAL.

METHODS

Consecutive patients with clinical suspicion for VAP were analyzed. All patients underwent bilateral BAL. A threshold of >10(4) colony-forming units (cfu)/mL was diagnostic for VAP (VAP positive). Samples were concordant if the organism(s) and thresholds from both lungs were diagnostically consistent. Organisms </=10(4) cfu/mL with growth on the contralateral sample >10(4) cfu/mL were considered false-negative samples.

RESULTS

Between November 2005 and April 2006, 73 patients were considered clinically suspicious for VAP. Forty-four (60%) patients were VAP positive. Twenty-eight (64%) VAP patients had concordant samples. Overall, there were 15 false-negative samples. Sole use of the unilateral samples to guide treatment would have inappropriately directed antibiotic avoidance and/or discontinuation in 25% of VAP patients. Influence of the chest radiograph was equivocal because of the presence of bilateral infiltrates in 80% of discordant samples.

CONCLUSIONS

Bilateral BAL improves the accuracy of bronchoscopy in diagnosing VAP. Unilateral BAL may be insensitive in patients with clinically significant contralateral infection.

Pulmonary contusions and critical care management in thoracic trauma

Many victims of thoracic trauma require ICU care and mechanical ventilatory support. Pressure and volume-limited modes assist in the prevention of ventilator-associated lung injury. Ventilator-associated pneumonia is a significant cause of posttraumatic morbidity and mortality. Minimizing ventilator days, secretion control, early nutritional support, and patient positioning are methods to reduce the risk of pneumonia.

Systemic complications after head injury: a clinical review

Non-neurological organ dysfunction is common after traumatic brain injury and is an independent contributor to morbidity and mortality. It represents a risk factor that is potentially amenable to treatment, and early recognition and prompt intervention may improve outcome. This article reviews the current evidence for the mechanisms and treatment of non-neurological organ dysfunction after head injury.

Nosocomial pneumonia

Nosocomial pneumonia remains an important infection that warrants continuing investigation. The past year has seen a number of reports further describing risk factors, controversial issues around diagnosis, and potential preventive strategies. For specific infecting organisms such as Legionnaire's disease and tuberculosis, further reports of issues related to water supply in the former and staff preventive programs in the latter have also been reported. Substantive advances in prevention or management have not, however, been identified.

Use of quantitative cultures and reduced duration of antibiotic regimens for patients with ventilator-associated pneumonia to decrease resistance in the intensive care unit

Ventilator-associated pneumonia is responsible for approximately half of the infections acquired in the intensive care unit and represents one of the principal reasons for the prescription of antibiotics in this setting. Invasive diagnostic methods, including bronchoalveolar lavage and/or protected specimen bronchial brushing, could improve the identification of patients with true bacterial pneumonia and facilitate decisions of whether to treat. These techniques also permit rapid optimization of the choice of antibiotics in patients with proven bacterial infection, once the results of respiratory tract cultures become available, based on the identity of the specific pathogens and their susceptibility to specific antibiotics, to avoid prolonged use of a broader spectrum of antibiotic therapy than is justified by the available information. Because unnecessary prolongation of antibiotic therapy for patients with true bacterial infection may lead to the selection of multidrug-resistant microorganisms without improving clinical outcome, efforts to reduce the duration of therapy for nosocomial infections are also warranted. An 8-day regimen can probably be standard for patients with ventilator-associated pneumonia. Possible exceptions to this recommendation include immunosuppressed patients, patients who are bacteremic or whose initial antibiotic therapy was not appropriate for the causative microorganism(s), and patients whose infection is with very difficult-to-treat microorganisms and show no improvement in clinical signs of infection.

The futility of the clinical pulmonary infection score in trauma patients

INTRODUCTION

The Clinical Pulmonary Infection Score (CPIS) has received much attention recently. Advocates have touted its use for the diagnosis and duration of therapy in patients with ventilator-associated pneumonia (VAP). However, little has been written about its utility in trauma patients. The clinical, physiologic, and radiologic components of the CPIS may be difficult to differentiate from the systemic effects of injury. Quantitative cultures of the lower airway have been shown to be efficacious in differentiating VAP from the systemic inflammatory response syndrome (SIRS). In this study, we evaluated the potential use of CPIS as the sole means for diagnosis of VAP in critically injured patients.

METHODS

Patients were identified from the VAP database maintained in our Level I trauma center. Only those who had CPIS calculated at the time of bronchoscopy with BAL were included. VAP required >or=10 colonies/mL on quantitative BAL for diagnosis. Antibiotic therapy was based on quantitative BAL results. Patients with <10 colonies/mL were diagnosed with SIRS. Sensitivity and specificity of a CPIS>6 for VAP diagnosis (confirmed by BAL) were calculated.

RESULTS

In all, 158 patients underwent 285 BALs. The overall incidence for VAP was 42%. Patients with episodes of VAP and SIRS were well matched for age, Injury Severity Score, APACHE II score, and Glasgow Coma Scale score. The average CPIS was 6.8 in patients with SIRS and 6.9 for those with VAP. Using a CPIS>6 as the threshold for VAP only yielded a sensitivity of 61% and a specificity of 43%.

CONCLUSIONS

CPIS cannot differentiate VAP from SIRS in critically injured patients. Using CPIS to initiate antibiotic therapy in trauma patients could be harmful. Whether CPIS is useful to determine duration of antibiotic therapy is unknown.

National nosocomial infection surveillance system: from benchmark to bedside in trauma patients

INTRODUCTION

Ventilator-associated pneumonia (VAP) is an important cause of morbidity and mortality in the injured patient. Identification of those with VAP is important both in immediate clinical decision making as well as for the epidemiologic evaluation of the disease and benchmarking of rates across institutions with variable practice patterns. Despite this, controversy exists over the optimal method of VAP diagnosis. Many centers currently use invasive culture methods such as bronchoalveolar lavage (BAL) for diagnosis. Another diagnostic method, and the most common epidemiologic tool used to track VAP, is the definition employed by the National Nosocomial Infections Surveillance (NNIS) system. This relies on a combination of clinical and culture data. Our goal was to evaluate the accuracy of the NNIS definition as compared with BAL diagnosis in trauma patients.

METHODS

Records of all ventilated patients admitted to the trauma intensive care unit at a Level I center who were evaluated for the presence of pneumonia over a 2.5-year period were reviewed. VAP diagnosis was established if > or =10 cfu/mL were cultured on BAL. VAP rates and time of onset were compared with the hospital infection control database, which defines VAP by NNIS criteria. Assuming BAL to be correct, sensitivity, specificity, and positive and negative predictive values were calculated for NNIS VAP.

RESULTS

From September 1, 2001, through December 31, 2003, 292 patients underwent BAL for suspected pneumonia. The pneumonia rate in this group was 34 per 1,000 ventilator days. The NNIS definition showed excellent overall agreement, with a rate of 36 per 1,000 ventilator days. The use of the NNIS definition for bedside decision making, however, is less accurate. Sensitivity and positive predictive value were reasonably good (84% and 83%, respectively), whereas specificity and negative predictive value suffer (69% and 69%, respectively). Most importantly, the use of NNIS would have led to no treatment in 16% of patients diagnosed with VAP by BAL.

CONCLUSIONS

Compared with strict bacteriologic criteria for VAP, the NNIS definition has good overall agreement and seems to have utility as an epidemiologic benchmarking tool in trauma patients. However, the NNIS definition has less utility as a bedside decision-making tool in this population, leading to under-treatment in a significant number of patients.

Candida sp. isolated from bronchoalveolar lavage: clinical significance in critically ill trauma patients

OBJECTIVE

Based on limited data, Candida sp. isolates from bronchoalveolar lavage (BAL) cultures in immunocompetent patients are thought to be contaminants rather than pathogens. The objective of this study was to determine the clinical significance of Candida sp. isolated from BAL cultures in critically ill trauma patients.

DESIGN AND SETTING

Retrospective study in a level 1 trauma intensive care unit.

PATIENTS AND PARTICIPANTS

All patients with Candida sp. isolated from BAL cultures over a 3-year period; 85 Candida positive BAL cultures from 62 patients were studied.

MEASUREMENTS AND RESULTS

The primary outcomes were the incidence of Candida sp. in BAL, antifungal use, course of the possible infection, and mortality. Of 1077 BAL cultures 85 (8%) grew Candida sp., representing 64 episodes of possible Candida sp. ventilator-associated pneumonia. No colony counts exceeded the diagnostic threshold for bacterial VAP (>or=10(5) cfu/ml). Only 2 of 64 episodes (3%) were treated with systemic antifungals. Three other episodes (5%) were treated because of concomitant therapy for Candida sp. at other sites. The majority of episodes were not treated with antifungals and were considered contaminants (59/64, 92%). No patients developed subsequent candidemia, and most follow-up BALs (74%) were negative for Candida sp. Overall mortality (17%) was similar to previous patients with similar severity of injury at the study center (18%).

CONCLUSIONS

The results of this study suggest that isolation of Candida sp. from BAL in quantities below the diagnostic threshold for VAP in this population does not require antifungal therapy.

Prospective comparison of bronchoalveolar lavage and quantitative deep tracheal aspirate in the diagnosis of ventilator associated pneumonia

BACKGROUND

Ventilator associated pneumonia (VAP) is common in trauma patients, and accurate diagnosis of VAP may improve survival. With the risk of development of bacterial resistance, we also strive to minimize the use of unnecessary antibiotics. Recent studies suggest that quantitative deep endotracheal aspirate (QDEA) is adequate in VAP diagnosis. We currently use bronchoalveolar lavage (BAL) diagnosis. The purpose of this study was to examine the accuracy of QDEA as compared with BAL in diagnosing VAP in trauma patients.

METHODS

We prospectively compared the results of BAL and QDEA in intubated patients suspected of having VAP during an 8-month period. Indication for BAL was pulmonary infiltrate, systemic inflammatory response syndrome, and C-reactive protein >17 mg/dL at > or =48 hours after admission. Study patients underwent QDEA immediately before BAL, and quantitative cultures were compared for both specimens. The techniques differ in that QDEA involves the direct culture of sputum suctioned from the distal trachea, whereas BAL involves lavage of the bronchoalveolar tree with sterile saline, which is then cultured. VAP was diagnosed on BAL if > or =10(5) cfu/mL was present on culture. The ability of QDEA to diagnose pneumonia was examined at cutoffs of > or =10(5) cfu/mL and > or =10(4) cfu/mL, as compared with BAL at > or =10(5).

RESULTS

Sixty-one patients underwent BAL during this period, and 39 of these underwent both BAL and QDEA for the study. Of the 39 studied patients between March 16, 2002, and November 4, 2002, 20 (51%) were found to have VAP by BAL (> or =10(5) cfu/mL). Using this cutoff for QDEA, 18 of 20 (90%) would have been correctly diagnosed. Using > or =10 cfu/mL for QDEA, the rate of correct diagnosis would increase to 19 of 20 (95%). However, of the 19 who did not have pneumonia according to BAL, 6 (31%) would have been incorrectly diagnosed with VAP using the QDEA cutoff of > or =10(5) cfu/mL. A QDEA cutoff of > or =10 (4) cfu/mL would result in the even higher false-positive rate of 8 of 19 patients (42%).

CONCLUSION

Whereas most patients with pneumonia by BAL would have been diagnosed by QDEA, use of QDEA in treatment decisions would have led to needless antibiotic administration in 31% of VAP-negative patients at a cutoff of > or =10(5) cfu/mL and 42% at > or =10(4) cfu/mL. The use of QDEA in VAP diagnosis is limited because of the rate of over-diagnosis. With the increasing problems associated with excess antibiotic use, we believe these results support the use of BAL over QDEA in the diagnosis of VAP in the ventilated trauma patient.

Aportación del laboratorio de microbiología al diagnóstico de la neumonía asociada a la ventilación mecánica

The etiologic diagnosis of ventilator-associated pneumonia (VAP) should be considered as a microbiological emergency due to its impact on morbidity and mortality. Sampling of the lower respiratory tract (LRT) must be performed before starting or modifying antimicrobial therapy. Surveillance cultures in patients without criteria of VAP are not recommended. There is no evidence of any superiority of bronchoscopic over non-bronchoscopic sampling procedures, but quantitative bacterial cultures are essential to allow colonization to be differentiated from true infection of the LRT. Under these conditions, negative cultures practically rule out bacterial infection or, at least, identify patients who will not benefit from antibiotic therapy or who will require a very short course of treatment. Given that identification and antimicrobial susceptibility testing of microorganisms usually takes up to 3 or 4 days, rapid procedures that provide the clinician with useful information are essential. Rapid information, even if partial or less than perfect, is clearly better for the patient than a perfect but delayed report. Gram stain of LRT secretions is an immediate procedure that can guide management and it has a reasonable correlation with culture results. At present, new antibiogram procedures, performed on direct clinical samples, allow presumptive identification and information on susceptibility to commonly used antibiotics in less than 24 hours after sampling. The impact of using this procedure in clinical practice is currently under research.

Transfusions result in pulmonary morbidity and death after a moderate degree of injury

BACKGROUND

Prior studies have suggested that blood transfusion (Tx) is associated with infectious and respiratory complications in trauma patients. However, these studies are difficult to interpret because of small sample size, inclusion of severely injured patients in traumatic shock, and combination of a variety of unrelated low-morbidity/mortality infections, such as wound, catheter-related, and urinary tract infection as outcomes. To eliminate these confounding variables, this study evaluates the association between delayed Tx and serious, well-defined respiratory complications (ventilator-associated pneumonia [VAP] and acute respiratory distress syndrome [ARDS]) and death in a cohort of intensive care unit (ICU) admissions with less severe (Injury Severity Score [ISS] < 25) blunt trauma who received no Tx within the initial 48 hours after admission.

METHODS

Patients with blunt injury and ISS < 25 admitted to the ICU over a 7-year period were identified from the registry and excluded if within 48 hours from admission they received any Tx or if they died. VAP required quantitative bronchoalveolar lavage culture (> or =10(5) colonies/mL), and ARDS required Pao2/Fio2 ratio < 200 mm Hg, *** no congestive heart failure, diffuse bilateral infiltrates, and peak airway pressure > 50 cm H2O for diagnosis. Outcomes were VAP, ARDS, and death.

RESULTS

Nine thousand one hundred twenty-six with blunt injury were ICU admissions, and 5,260 (58%) met study criteria (72% male). Means for age, ISS, and Glasgow Coma Scale score were 39, 12, and 14, respectively. There were 778 (15%) who received delayed Tx. Incidences of VAP, ARDS, and death were 5%, 1%, and 1%, respectively. Logistic regression analysis identified age, base excess, chest Abbreviated Injury Scale score, ISS, and any transfusion as significant predictors for VAP; chest Abbreviated Injury Scale score and transfusion as significant predictors for ARDS; and age and transfusion as significant predictors for death.

CONCLUSION

Delayed transfusion is independently associated with VAP, ARDS, and death in trauma patients regardless of injury severity. These data mandate a judicious transfusion policy after resuscitation and emphasize the need for safe and effective blood substitutes and transfusion alternatives.

Evaluation of a Clinical Pathway for Ventilator-Associated Pneumonia: Changes in Bacterial Flora and the Adequacy of Empiric Antibiotics over a Three-Year Period

BACKGROUND

Evaluation of causative pathogens is vital for optimizing empiric antibiotic therapy of ventilator-associated pneumonia (VAP). Based on previous data (Ann Surg 1998;227:743-755), empiric antibiotics for our VAP clinical pathway were modified to target early and late occurring pathogens (ampicillin/sulbactam during the first week of hospitalization; cefepime plus vancomycin afterwards). The objectives of this study were to compare organisms causing VAP over a three-year period to previous data, and to determine the adequacy of the empiric antibiotic regimens.

METHODS

A total of 299 critically ill trauma patients with VAP over a three-year period were studied retrospectively. The incidence of pathogens causing VAP in the study period were compared to a previously published study of a two-year period in our intensive care unit (ICU). Sensitivities of Pseudomonas aeruginosa and Acinetobacter baumannii were evaluated over the study period. The adequacy of empiric antibiotic therapy for each episode of VAP was determined. Therapy was considered to be adequate if one or more antibiotics had in vitro activity against the organism causing VAP.

RESULTS

Statistically significant changes in pathogens included increased Staphylococcus aureus (incidence 17% vs. 11%, p = 0.024) and decreased Acinetobacter baumannii (11% vs. 22%, p < 0.001). Susceptibility patterns were statistically unchanged except for increased resistance of P. aeruginosa to extended-spectrum penicillins (p = 0.016). Empiric therapy was adequate in 76% of VAP episodes.

CONCLUSIONS

The clinical pathway's empiric antibiotic regimen was associated with only modest changes in organisms causing VAP and provided a high rate of adequate empiric coverage.