Cefepime free minimum concentration to minimum inhibitory concentration (fCmin/MIC) ratio predicts clinical failure in patients with Gram-negative bacterial pneumonia

Cefepime is an antibiotic commonly used in nosocomial infections. The objective of this study was to elucidate the relationship between cefepime exposure and clinical outcome in patients with Gram-negative bacterial pneumonia. A previously published population pharmacokinetic model of cefepime was validated in 12 adult patients with normal renal function by measuring plasma concentrations at steady-state. Additionally, clinical outcomes for 33 patients with Gram-negative bacterial pneumonia who received cefepime monotherapy were determined. The free minimum concentration (fCmin) to MIC ratio for each patient was determined by conditioning the validated pharmacokinetic model using patient-specific creatinine clearance (CLCr), dosing regimen and cefepime MIC of the organism isolated, and was subsequently correlated with clinical failure. Classification and regression tree (CART) analysis was used to determine the most significant drug exposure breakpoint. Mean±S.D. CLCr and cefepime Cmin in the 12 patients were 87.5±21.2mL/min and 6.2±3.8mg/L, respectively. In comparison, the Cmin predicted by the pharmacokinetic model was 5.8mg/L using a CLCr of 90mL/min. MICs of organisms ranged from 0.5mg/L to 8mg/L. Percent time free drug above MIC of 100% was achieved in 32/33 patients, but 12 patients experienced clinical failure. CART analysis determined patients with an fCmin/MIC≥2.1 had a significantly lower risk of clinical failure (OR=0.11, 95% CI 0.02-0.67; P=0.017). The fCmin/MIC ratio is a useful predictor of clinical failure in Gram-negative bacterial pneumonia. The clinical utility of fCmin/MIC in therapeutic drug monitoring should be further explored.

Combination Therapy With Vancomycin and Ceftaroline for Refractory Methicillin-resistant Staphylococcus aureus Bacteremia: A Case Series

PURPOSE

Although vancomycin has been the mainstay of therapy for methicillin-resistant Staphylococcus aureus (MRSA) infections, its effectiveness has been challenged. Combination therapy may be used for patients with persistent MRSA bacteremia refractory to initial therapy. Studies have reported in vitro synergy between vancomycin and ceftaroline; however, clinical experience with this therapy is limited. Here, we report our experience with 5 cases of vancomycin-refractory MRSA bacteremia treated with the combination of vancomycin and ceftaroline.

METHODS

Between January 2014 and August 2016, 5 patients were identified who received vancomycin and ceftaroline combination therapy due to persistent bacteremia or deterioration of their clinical status on vancomycin alone (despite a vancomycin MIC within the susceptible range).

FINDINGS

Five patients presented with MRSA bacteremia secondary to endocarditis (n = 2), epidural abscess (n = 2), or left iliopsoas abscess (n = 1). Four of the 5 patients experienced microbiologic cure, and 1 patient transitioned to palliative care.

IMPLICATIONS

This case series serves to describe additional clinical experience with vancomycin and ceftaroline combination therapy. This combination may be considered when vancomycin monotherapy does not lead to microbiological and/or clinical improvement in patients with metastatic MRSA bacteremia. Additional studies are warranted to further define its role in salvage therapy for persistent MRSA bacteremia.

Corticosteroid use in ARDS and its application to evolving therapeutics for coronavirus disease 2019 (COVID-19): A systematic review

Data regarding the use of corticosteroids for treatment of acute respiratory distress syndrome (ARDS) are conflicting. As the coronavirus disease 2019 (COVID‐19) pandemic progresses, more literature supporting the use of corticosteroids for COVID‐19 and non‐COVID‐19 ARDS have emerged. Glucocorticoids are proposed to attenuate the inflammatory response and prevent progression to the fibroproliferative phase of ARDS through their multiple mechanisms and anti‐inflammatory properties. The purpose of this systematic review was to comprehensively evaluate the literature surrounding corticosteroid use in ARDS (non‐COVID‐19 and COVID‐19) in addition to a narrative review of clinical considerations of corticosteroid use in these patient populations. OVID Medline and EMBASE were searched. Randomized controlled trials evaluating the use of corticosteroids for COVID‐19 and non‐COVID‐19 ARDS in adult patients on mortality outcomes were included. Risk of bias was assessed with the Risk of Bias 2.0 tool. There were 388 studies identified, 15 of which met the inclusion criteria that included a total of 8877 patients. The studies included in our review reported a mortality benefit in 6/15 (40%) studies with benefit being seen at varying time points of mortality follow‐up (ICU survival, hospital, and 28 and 60 days) in the COVID‐19 and non‐COVID‐19 ARDS studies. The two non‐COVID19 trials assessing lung injury score improvements found that corticosteroids led to significant improvements with corticosteroid use. The number of mechanical ventilation‐free days significantly were found to be increased with the use of corticosteroids in all four studies that assessed this outcome. Corticosteroids are associated with improvements in mortality and ventilator‐free days in critically ill patients with both COVID‐19 and non‐COVID‐19 ARDS, and evidence suggests their use should be encouraged in these settings. However, due to substantial differences in the corticosteroid regimens utilized in these trials, questions still remain regarding the optimal corticosteroid agent, dose, and duration in patients with ARDS.

Clinical Outcomes in Patients With Gram-Negative Infections Treated With Optimized Dosing Cefepime Over Various Minimum Inhibitory Concentrations

BACKGROUND

The Clinical and Laboratory Standards Institute (CLSI) revised cefepime interpretive criteria, introducing the susceptible dose-dependent category for Enterobacteriaceae with a minimum inhibitory concentration (MIC) of 4 to 8 μg/mL in 2014. Limited clinical data support these new categories. This study compares outcomes of patients treated with standard and high-dose cefepime across various MICs.

METHODS

We retrospectively reviewed cases of pneumonia or bacteremia caused by gram-negative organisms treated with adequate doses of cefepime for ≥48 hours. Outcomes were compared for MICs of ≤2 (low), 4 (medium), and 8 μg/mL (high). The primary end point was clinical failure, the secondary end point was microbiological failure.

RESULTS

Ninety cases met the inclusion criteria: 46, 25, and 19 patients with low, medium, or high MIC, respectively. Multivariate logistic regression revealed that the medium (odds ratio [OR]: 9.13, P < .01) and high (OR: 6.79, P = .01) MIC groups had increased clinical failure.

CONCLUSION

Cefepime therapy, even at CLSI-recommended doses, had an increased risk of clinical failure for gram-negative pathogens with MICs of 4 or 8 μg/mL. This finding suggests that higher dosing regimens (2 g every 8 hours or 1 g every 6 hours) may be necessary to treat serious gram-negative infections with elevated MICs.

Single Dose of Sodium Zirconium Cyclosilicate Versus Sodium Polystyrene Sulfonate in Hospitalized Patients With Hyperkalemia

BACKGROUND

Sodium zirconium cyclosilicate (SZC) is an inorganic zirconium silicate compound that selectively exchanges potassium for hydrogen and sodium. "Once" doses of SZC (with option to redose) in patients with hyperkalemia in hospitalized settings have not been evaluated. We hypothesized that a once dose of SZC would be non-inferior to sodium polystyrene sulfonate (SPS) in reducing serum potassium.

OBJECTIVE

The objective of our study is to evaluate the effect of a "once" dose of SZC when compared with SPS in reducing serum potassium levels.

METHODS

This was a retrospective analysis of patients who received either a "once" dose of SZC or single or repeated doses of SPS for hyperkalemia. The primary endpoint was mean absolute reduction in the first serum potassium value at least 4 hours after administration. The secondary efficacy endpoints were the rate of additional potassium-lowering therapies and the rate of normokalemia within 48 hours. Safety endpoints were the incidence of electrolyte abnormalities, hypoglycemia, hypertension, hypotension, and colonic necrosis.

RESULTS

A total of 260 patients were included in the analysis. The mean initial serum potassium was similar between groups (5.6 ± 0.4). The absolute serum potassium reduction was -0.88 ± 0.64 mEq/L and -0.75 ± 0.65 mEq/L with SZC and SPS, respectively. The "once" regimen of SZC demonstrated non-inferiority compared with SPS (P < 0.0001). The proportion of patients achieving normokalemia within 48 hours and the proportion of patients receiving additional potassium-lowering therapies did not differ between groups.

CONCLUSION AND RELEVANCE

The "once" dose regimen (with redose option) of SZC was non-inferior to the "once" or repeated dosing regimen of SPS with regard to absolute potassium reduction. There were no significant differences in the rate of additional potassium-lowering therapies and the rate of normokalemia at 48 hours. The incidence of hypertension was less common among patients who received SZC.

Does Switching Norepinephrine to Phenylephrine in Septic Shock Complicated by Atrial Fibrillation With Rapid Ventricular Response Improve Time to Rate Control?

BACKGROUND

Atrial fibrillation (AF) frequently develops during critical illness. In septic shock complicated by rapid AF, the use of phenylephrine may be advantageous secondary to its β-1 sparing properties. However, evidence supporting this strategy is lacking.

OBJECTIVE

The purpose of this study is to determine the clinical effect on rate control of transitioning norepinephrine to phenylephrine in septic shock patients who develop AF with a rapid ventricular response (RVR).

METHODS

A single-center retrospective study of septic shock patients admitted to the medical or surgical intensive care unit (ICU) who developed AF with RVR (heart rate >110 beats per minute [bpm]). Patients who were switched to phenylephrine were compared to those who remained on norepinephrine. The primary end point was sustained achievement of rate control. A time-varying Cox proportional hazards model was used to assess the primary end point.

RESULTS

A total of 67 patients were included in the study, of which 28 were switched to phenylephrine. Baseline characteristics were similar between groups. The unadjusted hazard ratio for achieving rate control was significant at 1.99 (95% confidence interval [CI]: 1.19-3.34; P < .01) for the phenylephrine group. The adjusted hazard ratio was 1.75 (95% CI: 0.86-3.53; P = .12). There were no statistically significant differences in mortality or ICU length of stay.

CONCLUSION

Our study suggests a potential clinical effect on achieving rate control when switching to phenylephrine cannot be excluded. It remains unclear if there is a benefit on mortality or length of stay outcomes in critically ill patients.

Extended Versus Short-Course Corticosteroid Taper Regimens in the Management of Chronic Obstructive Pulmonary Disease Exacerbations in Critically Ill Patients

BACKGROUND

Previous literature has suggested that a short course of corticosteroids is similarly effective as an extended course for managing an acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, there are limited data regarding the optimal corticosteroid regimen in critically ill patients and the dosing strategies remain highly variable in this population.

METHODS

This retrospective cohort study evaluated patients with AECOPD admitted to the intensive care unit within a 2-year period. Patients were divided into short-course (≤5 days) or extended-course (>5 days) corticosteroid taper groups. The primary end point was treatment failure, defined as the need for intubation, reintubation, or noninvasive mechanical ventilation. Secondary end points included the duration of mechanical ventilation, hospital and intensive care unit length of stay, and adverse events.

RESULTS

Of the 151 patients who met the inclusion criteria, 94 received an extended taper and 57 received a short taper. Treatment failure occurred in 3 patients, who were all in the extended taper group (P = .17). In a propensity score-matched cohort, the hospital length of stay was 7 days in the short taper group compared to 11 days in the extended taper group (P < .0001). No differences in adverse events were observed.

CONCLUSION

A short-course corticosteroid taper in critically ill patients with AECOPD is associated with reduced hospital length of stay and decreased corticosteroid exposure without increased risk of treatment failure. A prospective randomized trial is warranted.

Safety and feasibility of crushing sevelamer tablets for enteral feeding tube administration

WHAT IS KNOWN AND OBJECTIVE

Sevelamer is an insoluble polymer indicated for the management of hyperphosphatemia in patients with chronic kidney disease (CKD). The package inserts for both tablet formulations recommend the tablets be administered whole. Due to whole tablets being sometimes inadvertently crushed and the significantly increased cost of sevelamer packets, we evaluated the safety and feasibility of crushed sevelamer tablets for enteral feeding tube administration.

METHODS

A single-centre retrospective chart review was performed. All adult ICU patients prescribed sevelamer carbonate between 1 January 2015 and 31 July 2019 were included if they received at least one dose of a sevelamer tablet or packet, whereas they had an enteral feeding tube in place. The primary outcome was the incidence of an obstructed enteral feeding tube or need for replacement, as defined as the number of occurrences over the total numbers of doses administered. The secondary outcome was the change in phosphorus levels from time of sevelamer initiation to discontinuation or patient discharge.

RESULTS

A total of 14 obstructions were reported, four in the tablet arm and ten in the packet arm (0.4% tablet arm, 0.5% packet arm; P = .5931). Of these, four (29%) required tube replacement and were followed by sevelamer discontinuation. Two (14%) were documented to be due to increased tube feeds and esomeprazole. Six (43%) cases required tube replacement, but no issues arose upon continuation. Only one of the obstructions resulted in a recurrent tube occlusion.

WHAT IS NEW AND CONCLUSION

Sevelamer tablets may be crushed and administered via enteral feeding tubes, provided clear instruction on tablet preparation is included. Oral administration in dysphagic patients requires further evaluation with clear protocols for preparation and administration.

Safety and Feasibility of Opening Tamsulosin Capsules for Enteral Feeding Tube Administration

Purpose: Tamsulosin is formulated as sustained release beads within a capsule to prevent rapid absorption and associated hypotension. The package insert advises the capsule is swallowed whole; not crushed, chewed, or opened. To our knowledge, there are no current data on opening capsules for adults with enteral tube feeds. Given the unidentified safety and efficacy of administration via enteral tubes, alternative alpha blockers with less selectivity for alpha1A are often used. Methods: A single center retrospective chart review was conducted at two hospital sites. Adult patients that received at least one dose of tamsulosin or doxazosin while an enteral feeding tube was placed were included. Safety outcomes evaluated were the number of documented tube obstructions and incidence of medication associated hypotension. Results: 169 patients were included. Ten enteral feeding tube obstructions were reported, 4 of 110 (3.64%) in the tamsulosin arm and 6 of 59 (10.17%) in the doxazosin arm (RR .36, 95% CI .11 to 1.22, P = .099). At least 1 episode of medication associated hypotension occurred in 22 of 98 (22.45%) in the tamsulosin arm and 20 of 49 (40.82%) in the doxazosin arm (RR .55, 95% CI .33 to .91, P = .019). Conclusion: There was no statistically significant difference in the number of tube obstructions between patients receiving tamsulosin or doxazosin via enteral tube feeds. Patients receiving doxazosin were at increased risk of experiencing medication related hypotension. Tamsulosin capsules may be opened and administered via enteral feeding tubes if administered with content integrity intact.

Hyperamylasemia: a result of intracranial bleeding

The unexpected finding of hyperamylasemia in a patient with isolated head injury prompted a study of amylase levels in patients with various degrees of cranial trauma. None of seven patients with isolated maxillofacial trauma had hyperamylasemia. This group was studied to discount injury to salivary glands as a source of elevated amylase levels. Only one of ten patients with simple cranial injury without computerized tomographic (CT) scan evidence of intracranial bleeding had hyperamylasemia. Six of ten patients with CT scans positive for intracranial bleeding had hyperamylasemia. Isoamylase analysis showed that the source of the hyperamylasemia was varied. These results suggest a central neural control of serum amylase levels. The reliability of the serum amylase level as an indication of pancreatic trauma in a patient with concomitant head injury is questioned.