Adjunctive aerosolized colistin for multi-drug resistant gram-negative pneumonia in the critically ill: a retrospective study.

BACKGROUND: The incidence of multi-drug resistant (MDR) gram-negative (GN) organisms including Pseudomonas and Acinetobacter spp has increased in the last decade, prompting re-evaluation of colistin for the management of these infections. Aerosolized colistin as an adjunct to intravenous therapy is a current option for the management of MDR-GN pneumonia, although data supporting this practice is limited. This study evaluates the efficacy of adjunctive aerosolized colistin in combination with intravenous colistin in critically ill patients with MDR-GN pneumonia. METHODS: A retrospective multi-center cohort analysis comparing critically ill patients with MDR-GN pneumonia who received intravenous colistin (IV) alone or in combination with adjunctive aerosolized colistin (IV/AER) with a primary endpoint of clinical cure at the end of colistin therapy. Secondary endpoints included microbiologic cure, duration of mechanical ventilation, length of stay, and hospital mortality. A post-hoc subgroup analysis was performed for patients with high quality cultures used for diagnosis of MDR-GN pneumonia. Dichotomous data were compared using Fisher's exact test while the student's t-test or Mann-Whitney U test were used for continuous variables. RESULTS: Ninety-five patients met criteria for evaluation with 51 patients receiving IV and 44 receiving IV/AER. Baseline characteristics were similar between the two groups. Twenty patients (39.2%) receiving IV and 24 (54.5%) receiving IV/AER achieved clinical cure (p = 0.135). There was no difference in microbiologic cure rates between the IV and IV/AER colistin groups (40.7vs. 44.4%, p = 0.805). The IV group demonstrated a trend towards higher pneumonia attributable mortality (70.4 vs. 40%, p = 0.055). In the subgroup analysis of patients with high quality respiratory cultures, there was a significantly lower clinical cure rate for those in the IV group as compared to the IV/AER group (31.3 vs. 57.1%, p = 0.033). CONCLUSIONS: Addition of aerosolized colistin to IV colistin may improve clinical cure and mortality for patients with MDR-GN pneumonia. Larger, prospective trials are warranted to confirm the benefit of adjunctive aerosolized colistin in critically ill patients with MDR-GN pneumonia.

Prolonged infusion antibiotics for suspected gram-negative infections in the ICU: a before-after study.

BACKGROUND: ß-Lactam antibiotics demonstrate time-dependent killing. Prolonged infusion of these agents is commonly performed to optimize the time the unbound concentration of an antibiotic remains greater than the minimum inhibitory concentration and decrease costs, despite limited evidence suggesting improved clinical results. OBJECTIVE: To determine whether prolonged infusion of ß-lactam antibiotics improves outcomes in critically ill patients with suspected gram-negative infection. METHODS: We conducted a single-center, before-after, comparative effectiveness trial between January 2010 and January 2011 in the intensive care units at Barnes-Jewish Hospital, an urban teaching hospital affiliated with the Washington University School of Medicine in St. Louis, MO. Outcomes were compared between patients who received standardized dosing of meropenem, piperacillin-tazobactam, or cefepime as an intermittent infusion over 30 minutes (January 1, 2010, to June 30, 2010) and patients who received prolonged infusion over 3 hours (August 1, 2010, to January 31, 2011). RESULTS: A total of 503 patients (intermittent infusion, n = 242; prolonged infusion, n = 261) treated for gram-negative infection were included in the clinically evaluable population. Approximately 50% of patients in each group received cefepime and 20% received piperacillin-tazobactam. More patients in the intermittent infusion group received meropenem (35.5% vs 24.5%; p = 0.007). Baseline characteristics were similar between groups, with the exception of a greater occurrence of chronic obstructive pulmonary disease (COPD) in the intermittent infusion group. Treatment success rates in the clinically evaluable group were 56.6% for intermittent infusion and 51.0% for prolonged infusion (p = 0.204), and in the microbiologically evaluable population, 55.2% for intermittent infusion and 49.5% for prolonged infusion (p = 0.486). Fourteen-day, 30-day, and inhospital mortality rates in the clinically evaluable population for the intermittent and prolonged infusion groups were 13.2% versus 18.0% (p = 0.141), 23.6% versus 25.7% (p = 0.582), and 19.4% versus 23.0% (p = 0.329). CONCLUSIONS: Routine use of prolonged infusion of time-dependent antibiotics for the empiric treatment of gram-negative bacterial infections offers no advantage over intermittent infusion antibiotic therapy with regard to treatment success, mortality, or hospital length of stay. These results were confirmed after controlling for potential confounders in a multivariate analysis.

Occurrence and predictors of dexmedetomidine infusion intolerance and failure.

BACKGROUND: Dexmedetomidine, a selective α2 adrenergic receptor agonist, exhibits sedative, analgesic, anxiolytic, and sympatholytic effects, and may aid in controlling agitation in the intensive care unit (ICU). At our hospital (Barnes-Jewish Hospital, St. Louis, MO), dexmedetomidine is commonly used as a sedative in the medical ICU. Predictors of dexmedetomidine intolerance or failure have not yet been defined. OBJECTIVE: Describe the rate of dexmedetomidine infusion intolerance/failure and identify patient predictors of intolerance/failure. METHODS: This retrospective single-center cohort study evaluated 75 mechanically ventilated adults who received dexmedetomidine infusion. Patients were included in the study if they were aged ≥ 18 years; mechanically ventilated for > 24 hours; received dexmedetomidine infusion for ≥ 1 hour following > 24 hours of continuous infusions of midazolam, fentanyl, or propofol; and were admitted to our medical ICU between August 1, 2009 and August 1, 2010. Multivariate logistic regression analysis was performed to identify independent predictors of intolerance/failure. RESULTS: A total of 85 episodes of dexmedetomidine infusion were analyzed (75 total patients). Eighteen episodes (21%) met the criteria for intolerance/failure and 67 episodes (79%) met the criteria for tolerance/success. The median duration of mechanical ventilation, total dexmedetomidine infusion time, and ICU length of stay did not differ between groups. Nonblack race was the only variable independently associated with treatment failure or intolerance in the logistic regression analysis. CONCLUSION: Twenty-one percent of dexmedetomidine infusion episodes met the criteria for intolerance/failure. No predictors of intolerance/failure were found to be clinically significant.

Use of adjunctive aerosolized antimicrobial therapy in the treatment of Pseudomonas aeruginosa and Acinetobacter baumannii ventilator-associated pneumonia.

BACKGROUND: Adjunctive aerosolized antibiotics (AAA) have been recommended in the setting of Gram-negative ventilator-associated pneumonia (VAP), but little is known about their influence on clinical outcomes. OBJECTIVE: To assess outcomes associated with AAA for the treatment of Pseudomonas aeruginosa (PA) and Acinetobacter baumannii (AB) VAP. METHODS: A retrospective, single-center cohort study at Barnes-Jewish Hospital in St Louis, Missouri. Consecutive subjects treated for bronchoalveolar lavage-confirmed PA or AB VAP between January 1, 2004 and December 31, 2009 were enrolled. Records of subjects treated with AAA were compared to those who did not receive AAAs (NAAA). RESULTS: Ninety-three patients were evaluated (NAAA n = 74, AAA n = 19, inhaled colistin n = 9, inhaled tobramycin n = 10). Patients receiving AAA were significantly more likely to be infected with multidrug-resistant bacteria (52.6% vs 14.9%, P < .001) and had greater Acute Physiology and Chronic Health Evaluation II scores (21.4 ± 5.7 vs 17.5 ± 5.3, P = .004) compared to patients receiving NAAA. NAAA subjects experienced a shorter time from VAP onset to appropriate intravenous antibiotic initiation (0.5 ± 0.9 d vs 2.6 ± 5.4 d, P = .038), but length of intravenous therapy was similar between groups (12.8 ± 8.5 d vs 17.8 ± 13.3 d, P = .16). The NAAA group demonstrated significantly shorter mechanical ventilation duration (18.9 ± 15.9 d vs 38.4 ± 32.4 days, P < .001), intensive care unit stay (37.5 ± 42.5 d vs 56.3 ± 31.3 d, P = .001), and hospital stay (39.0 ± 42.5 d vs 58.3 ± 33.4 d, P = .001). However, Kaplan-Meier curves for the probability of 30-day survival from VAP onset demonstrated that patients receiving AAA had statistically greater survival (P = .030 by the log rank test). CONCLUSIONS: Patients with PA and AB VAP may experience favorable survival when treated with AAA, despite greater severity of illness and a greater incidence of multidrug-resistant infection. Large randomized trials are needed to further explore this therapy.

Antibiotic stewardship in the intensive care unit.

Antimicrobial stewardship encompasses the optimization of agent selection, dose, and duration leading to the best clinical outcome in the treatment or prevention of infection. Ideally, these goals are met while producing the fewest side effects and lowest risk for subsequent resistance. The concept of antimicrobial stewardship can be directly applied to the prescription of empirical antibiotic therapy in the intensive care unit (ICU) because it is well described that inappropriate initial regimens lead to increased mortality. As such, care should be taken to identify factors that place patients at risk for infection with pathogens demonstrating reduced susceptibility or multidrug resistance. Research efforts have concentrated on molecular diagnostic techniques to aid in more rapid organism detection and thus potential for earlier therapy appropriateness and deescalation, although limitations prohibiting widespread implementation of this technology exist. Also of great importance with regard to stewardship efforts is infection prevention. Effective prophylactic strategies reduce the occurrence of nosocomial infections and may therefore improve patient outcomes while obviating the need for otherwise necessary antimicrobial exposure.

Optimizing sustained use of sedation in mechanically ventilated patients: focus on safety.

Optimizing sustained use of ICU sedation in mechanically ventilated patients requires careful consideration of drug-specific characteristics (E.G. pharmacokinetics), consideration of potential adverse effects in susceptible patients, and utilization of sedation-minimizing strategies. In the era of anxiolytic dosing protocols adjusted to specific patient behaviors as defined by sedation scales in conjunction with daily interruption, midazolam is a reasonable option for long-term sedation. Propofol is an appealing agent for ICU sedation due to it's pharmacokinetic profile and a reduced propensity to result in prolonged sedation. However, care should be taken to monitor for potential devastating adverse effects including hypertriglyceridemia and propofol-related infusion syndrome (PRIS). Dexmedetomidine unreliably provides adequate sedation at doses currently approved by the FDA, though upward titration of dexmedetomidine coupled with rescue benzodiazepines and/or fentanyl appears to be safe and comparable to benzodiazepines in the achievement of light to moderate Richmond Agitation Sedation Scale (RASS) goals. Clinicians should closely monitor patients receiving dexmedetomidine for hemodynamic-altering bradycardia. Strategies that promote frequent patient assessment with corresponding sedative dose minimization have demonstrated the benefits of limiting oversedation. Implementation of a sedation protocol requires careful consideration of ICU resources and staffing such that efforts made are sustainable and will be safe and effective for the patient population affected.

Hospital resource utilization and costs of inappropriate treatment of candidemia.

STUDY OBJECTIVES: To evaluate the impact of inappropriate therapy--defined as delayed antifungal therapy beyond 24 hours from culture collection, inadequate antifungal dosage, or administration of an antifungal to which an isolate was considered resistant--on postculture hospital length of stay and costs, and to evaluate the relationship between modifiable risk factors, including failure to remove a central venous catheter, antifungal delay, and inadequate dosage, for an additive effect on hospital length of stay and costs. DESIGN: Single-center retrospective cohort study. SETTING: 1250-bed academic medical center. PATIENTS: One hundred sixty-seven consecutive adult patients admitted between January 2004 and May 2006 with culture-confirmed Candida bloodstream infections that occurred within 14 days of hospital admission and who received at least one dose of antifungal treatment. MEASUREMENTS AND MAIN RESULTS: Patients were stratified according to appropriateness of antifungal therapy. Appropriate therapy was defined as initiation of an antifungal to which the isolated pathogen was sensitive in vitro within 24 hours of positive culture collection, in addition to receipt of an adequate dose as recommended by the Infectious Diseases Society of America and the antifungal package insert. Postculture length of stay was the primary outcome and hospital costs the secondary outcome. An evaluation of modifiable risk factors was performed separately. Data were analyzed for 167 patients (22 in the appropriate therapy group and 145 in the inappropriate therapy group). Postculture length of stay was shorter in the appropriate therapy group (mean 7 vs 10.4 days, p=0.037). This correlated with total hospital costs that were lower in the appropriate therapy group (mean $15,832 vs $33,021, p<0.001.) A graded increase in costs was noted with increasing number of modifiable risk factors (p=0.001). CONCLUSION: Inappropriate therapy for Candida bloodstream infection occurring within 14 days of hospitalization was associated with prolonged postculture length of stay and increased costs. A rise in costs, but not length of stay, was noted with increasing modifiable risk factors.

Assessment of an alternative meropenem dosing strategy compared with imipenem-cilastatin or traditional meropenem dosing after cefepime failure or intolerance in adults with neutropenic fever.

STUDY OBJECTIVE: To compare clinical outcomes of patients receiving an alternative dosage of meropenem with those of patients receiving imipenem-cilastatin or the traditional dosage of meropenem after failure of or intolerance to cefepime for treatment of febrile neutropenia. DESIGN: Retrospective, single-center cohort study. SETTING: 1250-bed urban academic medical center. PATIENTS: One hundred twenty-seven adults with neutropenic fever who received either imipenem-cilastatin or meropenem; imipenem-cilastatin was the preferred carbapenem until September 1, 2006, after which meropenem became the formulary carbapenem. MEASUREMENTS AND MAIN RESULTS: Of the 127 patients, 40 received imipenem-cilastatin 500 mg every 6 hours between September 1, 2005, and August 31, 2006; 87 patients received meropenem between September 1, 2006, and August 31, 2007: 29 received a traditional dosage of meropenem 1 g every 8 hours, and 58 received an alternative dosage of meropenem 500 mg every 6 hours. Primary outcomes of time to defervescence (median 3 vs 2 vs 3 days), need for additional antibiotics (20% vs 17% vs 14%), and time to receipt of additional antibiotics (median 5 vs 2 vs 1 days) were not significantly different among the imipenem-cilastatin, traditionally dosed meropenem, and alternatively dosed meropenem groups, respectively. In addition, significant differences in secondary outcomes, which were treatment duration (median 10 vs 8 vs 8 days), seizure rate (0% vs 0% vs 0%), in-hospital mortality (5% vs 7% vs 7%), and 30-day mortality (13% vs 7% vs 14%), were not identified among the three groups, respectively. CONCLUSION: The alternative meropenem dosage of 500 mg every 6 hours yielded similar patient outcomes, including time to defervescence, need for additional antibiotics, duration of therapy, and mortality, when compared with the traditional meropenem dosage and imipenem-cilastatin in adults with febrile neutropenia. In addition, no adverse effects on clinical outcomes were observed with the alternative dosage of meropenem.