Pharmacokinetics of Telavancin at Fixed Doses in Normal-Body-Weight and Obese (Classes I, II, and III) Adult Subjects.

A recommended total-body-weight (TBW) dosing strategy for telavancin may not be optimal in obese patients. The primary objective of this study was to characterize and compare the pharmacokinetics (PK) of telavancin across four body size groups: normal to overweight and obese classes I, II, and III. Healthy adult subjects (n = 32) received a single, weight-stratified, fixed dose of 500 mg (n = 4), 750 mg (n = 8), or 1,000 mg (n = 20) of telavancin. Noncompartmental PK analyses revealed that subjects with a body mass index (BMI) of ≥40 kg/m2 had a higher volume of distribution (16.24 ± 2.7 liters) than subjects with a BMI of <30 kg/m2 (11.71 ± 2.6 liters). The observed area under the concentration-time curve from time zero to infinity (AUC0-∞) ranged from 338.1 to 867.3 mg · h/liter, with the lowest exposures being in subjects who received 500 mg. AUC0-∞ values were similar among obese subjects who received 1,000 mg. A two-compartment population PK model best described the plasma concentration-time profile of telavancin when adjusted body weight (ABW) was included as a predictive covariate. Fixed doses of 750 mg and 1,000 mg had similar target attainment probabilities for efficacy as doses of 10 mg/kg of body weight based on ABW and TBW, respectively. However, the probability of achieving a target area under the concentration-time curve from time zero to 24 h of ≥763 mg · h/liter in association with acute kidney injury was highest (19.7%) with TBW-simulated dosing and lowest (0.4%) at the 750-mg dose. These results suggest that a fixed dose of 750 mg is a safe and effective alternative to telavancin doses based on TBW or ABW for the treatment of obese patients with normal renal function and Staphylococcus aureus infections. (This study has been registered at ClinicalTrials.gov under identifier NCT02753855.).

Phase I Study To Evaluate the Pharmacokinetics, Safety, and Tolerability of Two Dosing Regimens of Oral Fosfomycin Tromethamine in Healthy Adult Participants.

The pharmacokinetics (PK), safety, and tolerability of two repeated dosing regimens of oral fosfomycin tromethamine were evaluated in 18 healthy adult subjects. Subjects received 3 g every other day (QOD) for 3 doses and then every day (QD) for 7 doses, or vice versa, in a phase I, randomized, open-label, two-period-crossover study. Serial blood (n = 11) and urine (n = 4 collection intervals) samples were collected before and up to 24 h after dosing on days 1 and 5, along with predose concentrations on days 3 and 7. PK parameters were similar between days 1 and 5 within and between dosing regimens. The mean (± standard deviation [SD]) PK parameters for fosfomycin in plasma on day 5 during the respective QOD and QD dosing regimens were as follows: maximum concentration of drug in serum (Cmax) = 24.4 ± 6.2 versus 23.8 ± 5.6 µg/ml, time to Cmax (Tmax) = 2.2 ± 0.7 versus 2.0 ± 0.4 h, apparent volume of distribution (V/F) = 141 ± 67.9 versus 147 ± 67.6 liters, apparent clearance (CL/F) = 21.4 ± 8.0 versus 20.4 ± 5.3 liters/h, renal clearance (CLR) = 7.5 ± 4.1 versus 7.3 ± 3.5 liters/h, area under the concentration-time curve from 0 to 24 h (AUC0-24) = 151.6 ± 35.6 versus 156.6 ± 42.5 µg · h/ml, and elimination half-life (t1/2) = 4.5 ± 1.1 versus 5.0 ± 1.7 h. Urine concentrations peaked at approximately 600 µg/ml through the 0- to 8-h urine collection intervals but displayed significant interindividual variability. Roughly 35 to 40% of the 3-g dose was excreted in the urine by 24 h postdose. No new safety concerns were identified during this study. The proportion of diarrhea-free days during the study was significantly lower with the QD regimen than with the QOD regimen (61% versus 77%; P < 0.0001). Further studies to establish the clinical benefit/risk ratio for repeated dosing regimens of oral fosfomycin tromethamine are warranted. (This trial is registered at ClinicalTrials.gov under registration no. NCT02570074.).

Pharmacokinetics and Dialytic Clearance of Ceftazidime-Avibactam in a Critically Ill Patient on Continuous Venovenous Hemofiltration.

Ceftazidime-avibactam administered at 1.25 g every 8 h was used to treat multidrug-resistant Pseudomonas aeruginosa bacteremia in a critically ill patient on continuous venovenous hemofiltration (CVVH). Prefiltration plasma drug concentrations of ceftazidime and avibactam were measured at 0, 1, 2, 4, 6, and 8 h along with postfiltration and ultrafiltrate concentrations at h 2 and h 6. Plasma pharmacokinetic parameters of ceftazidime and avibactam, respectively, were as follows: maximum plasma concentration (Cmax), 61.10 and 14.54 mg/liter; minimum plasma concentration (Cmin), 31.96 and 8.45 mg/liter; half-life (t1/2), 6.07 and 6.78 h; apparent volume of distribution at the steady state (Vss), 27.23 and 30.81 liters; total clearance at the steady state (CLss), 2.87 and 2.95 liters/h; area under the concentration-time curve from 0 to 8 h (AUC0-8), 347.87 and 85.69 mg · h/liter. Concentrations of ceftazidime in plasma exceeded the ceftazidime-avibactam MIC (6 mg/liter) throughout the 8-h dosing interval. Mean CVVH extraction ratios for ceftazidime and avibactam were 14.44% and 11.53%, respectively, and mean sieving coefficients were 0.96 and 0.93, respectively. The calculated mean clearance of ceftazidime by CVVH was 1.64 liters/h and for avibactam was 1.59 liters/h, representing 57.1% of the total clearance of ceftazidime and 54.3% of the total clearance of avibactam. Further data that include multiple patients and dialysis modes are needed to verify the optimal ceftazidime-avibactam dosing strategy during critical illness and CVVH.

Clinical use of the polymyxins: the tale of the fox and the cat.

BACKGROUND: There is a need to identify practice patterns of polymyxin use, quantify gaps in knowledge, and recognize areas of persistent confusion. METHODS: A structured electronic survey was distributed to physicians, pharmacists and microbiologists. Demographic information was obtained, along with data regarding availability, stewardship principles, therapeutic usage, dosing, microbiological testing, and knowledge, attitudes and beliefs regarding the polymyxins. RESULTS: In total, there were 420 respondents with a median of 8 (interquartile range 4-15) years of experience in infectious diseases (52.5%) and critical care (35%). Of the respondents who reported that only one polymyxin was available for use, 17.1% used polymyxin B. Over half (52.5%) of the respondents utilized a loading dose very often/always, and 66.8% dosed both polymyxins in milligrams, with the most common doses of colistin and polymyxin B being 2.5 mg/kg twice daily (60.3%) and 1.5 mg/kg twice daily (65%), respectively, for patients with normal renal function. Polymyxins were most often used for respiratory infections (63%) in combination with a carbapenem (63.6%). Approximately 85% of respondents reported their knowledge level to be fair, good or very good, although 34.9% answered two of the three knowledge questions incorrectly. More than 70% of respondents agreed that confusion exists in all surveyed areas of polymyxin use. Almost all respondents (91.2%) agreed that a polymyxin guideline would be a helpful resource. CONCLUSIONS: This survey revealed objective and subjective variability in the use and perception of the polymyxins, and identified several areas in which they were being used contrary to the available evidence. The information provided herein lays the framework to harmonize clinical practice, guide future research and shape consensus guidelines.

Impact of Clinical and Laboratory Standards Institute breakpoint changes on susceptibility rates of cephalosporins in uncomplicated urinary tract infections caused by Enterobacteriaceae.

Breakpoint changes may impact cephalosporin susceptibility rates in uncomplicated urinary tract infections (uUTIs). Applying the ≤16-mg/L breakpoint to urine cultures from adult women in an academic health system resulted in cefazolin being the most active uUTI antimicrobial, with 86.9% susceptibility, compared to levofloxacin (80%), nitrofurantoin (76.5%), and sulfamethoxazole-trimethoprim (72.6%).

Effectiveness of Probiotic for Primary Prevention of Clostridium difficile Infection: A Single-Center Before-and-After Quality Improvement Intervention at a Tertiary-Care Medical Center.

OBJECTIVETo evaluate probiotics for the primary prevention of Clostridium difficile infection (CDI) among hospital inpatients.DESIGNA before-and-after quality improvement intervention comparing 12-month baseline and intervention periods.SETTINGA 694-bed teaching hospital.INTERVENTIONWe administered a multispecies probiotic comprising L. acidophilus (CL1285), L. casei (LBC80R), and L. rhamnosus (CLR2) to eligible antibiotic recipients within 12 hours of initial antibiotic receipt through 5 days after final dose. We excluded (1) all patients on neonatal, pediatric and oncology wards; (2) all individuals receiving perioperative prophylactic antibiotic recipients; (3) all those restricted from oral intake; and (4) those with pancreatitis, leukopenia, or posttransplant. We defined CDI by symptoms plus C. difficile toxin detection by polymerase chain reaction. Our primary outcome was hospital-onset CDI incidence on eligible hospital units, analyzed using segmented regression.RESULTSThe study included 251 CDI episodes among 360,016 patient days during the baseline and intervention periods, and the incidence rate was 7.0 per 10,000 patient days. The incidence rate was similar during baseline and intervention periods (6.9 vs 7.0 per 10,000 patient days; P=.95). However, compared to the first 6 months of the intervention, we detected a significant decrease in CDI during the final 6 months (incidence rate ratio, 0.6; 95% confidence interval, 0.4-0.9; P=.009). Testing intensity remained stable between the baseline and intervention periods: 19% versus 20% of stools tested were C. difficile positive by PCR, respectively. From medical record reviews, only 26% of eligible patients received a probiotic per the protocol.CONCLUSIONSDespite poor adherence to the protocol, there was a reduction in the incidence of CDI during the intervention, which was delayed ~6 months after introducing probiotic for primary prevention.Infect Control Hosp Epidemiol 2018;765-770.

Immunologic and Virologic Outcomes of Obese and Nonobese Incarcerated Adults on Antiretroviral Therapy for HIV Infection.

BACKGROUND: Obesity is common among patients with HIV. The objective of this study was to characterize response to antiretroviral therapy (ART) in a cohort of obese incarcerated adults compared to a nonobese cohort. METHODS: A retrospective matched cohort study was conducted in an HIV telemedicine clinic. Patients with body mass index (BMI) >30 kg/m2 who received the same ART with >95% adherence for at least 6 months were matched to nonobese patients by age, gender, ART, CD4 count, and viral load at baseline. RESULTS: Twenty pairs were included, with an average BMI of 24 kg/m2 in the nonobese cohort and 35 kg/m2 in the obese cohort. No difference was observed in the proportion of patients who achieved virologic suppression or the change in CD4 count from baseline to 6 to 12 months. CONCLUSION: This study revealed no differences in immunologic recovery or virologic suppression between obese and nonobese patients in an adult correctional population.

Economic Barriers in the Treatment of Clostridium difficile Infection With Oral Vancomycin.

Vancomycin is an increasingly important option for the treatment of Clostridium difficile infection, but economic barriers to its use remain significant in the outpatient setting. Generic vancomycin capsules are still inexplicably expensive and not universally covered by insurers. This report highlights the potential adverse consequences of cost-related nonadherence to vancomycin therapy and the challenges that clinicians face when prescribing oral vancomycin.

Methicillin-Resistant Staphylococcus aureus Pneumonia in Critically Ill Trauma and Burn Patients: A Retrospective Cohort Study.

BACKGROUND: The timing and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in trauma patients are not well characterized. This information is critical for the selection of appropriate empiric antibiotics. The objective of this study was to determine the incidence of MRSA pneumonia in early-onset and late-onset pneumonia and to identify risk factors for MRSA in the trauma-burn intensive care unit (ICU). PATIENTS AND METHODS: We conducted a retrospective cohort study from January 2012 to March 2015 of patients in the trauma and burn ICU with clinical and microbiologic evidence of pneumonia. Demographics, injury type and severity, co-morbidities, antimicrobial agents, and MRSA nasal colonization at ICU admission were extracted from the medical record. A multi-variable exact logistic regression was performed to assess predictors of MRSA pneumonia. RESULTS: Eighty patients with 88 episodes of pneumonia were included in the cohort. Ten patients had MRSA pneumonia, an overall incidence of 11.4% of pneumonia episodes with a median onset of seven days. The proportion of MRSA pneumonia episodes was not significantly different in early-onset (<5 days) or late-onset pneumonia, and there were no statistically significant risk factors for developing MRSA pneumonia. The majority of patients with MRSA had at least one known risk factor including homelessness, substance abuse, and receipt of broad-spectrum antibiotic agents. CONCLUSIONS: The 11.4% overall incidence of MRSA pneumonia in this trauma-burn cohort was similar to what has been reported in other trauma populations, although MRSA was equally likely to be identified in early- and late-onset pneumonia. Our results suggest that risk factors other than duration of hospitalization may be important considerations in the decision to initiate MRSA-active empiric therapy for pneumonia in the trauma-burn ICU.

Nephrotoxicity Associated with Concomitant Use of Ledipasvir-Sofosbuvir and Tenofovir in a Patient with Hepatitis C Virus and Human Immunodeficiency Virus Coinfection.

Direct-acting antivirals (DAAs) have revolutionized the treatment of hepatitis C virus (HCV) infection, with superior efficacy and safety compared to interferon-based therapies. Despite these improvements, drug interactions with DAAs exist and may be clinically relevant in human immunodeficiency virus (HIV)-coinfected patients. We present a case of nephrotoxicity associated with concomitant use of tenofovir disoproxil fumarate (TDF) and ledipasvir-sofosbuvir (LDV-SOF). A 56-year-old woman with HIV infection who had been taking efavirenz/tenofovir/emtricitabine (EFV/TDF/FTC) for 6 years developed acute kidney injury 8 weeks after initiating LDV-SOF for the treatment of HCV infection. Her serum creatinine concentration peaked at 10 mg/dL, compared with her baseline concentration of 0.9-1 mg/dL. Kidney biopsy revealed acute tubular necrosis and acute interstitial nephritis. Both LDV-SOF and TDF were discontinued, and the patient's serum creatinine concentration decreased to 1.3 mg/dL over the following 6 weeks. We postulate that this adverse drug reaction may have been secondary to the known interaction between ledipasvir and TDF, which results in increased TDF exposure. Despite knowledge of this interaction, LDV-SOF is commonly prescribed in patients with HIV-HCV coinfection, as patients who received LDV-SOF- and TDF-containing regimens in trials have not demonstrated adverse clinical consequences related to this interaction. This case highlights the rare but potentially serious nephrotoxicity that can result from TDF toxicity and serves as a reminder to clinicians to implement close renal function monitoring in patients receiving both LDV-SOF and TDF. Clinicians prescribing LDV-SOF to HCV-HIV-coinfected patients receiving TDF should be cautious about use with concomitant nephrotoxic medications and monitor markers of tubular dysfunction, including urinary phosphorus excretion, and renal injury at baseline and week 4 of therapy. Tenofovir alafenamide and alternative DAAs may also have a role in the management of patients at high risk for renal adverse effects from TDF.