Estimation of creatinine clearance in end-stage liver disease.

BACKGROUND: Estimation of renal function in patients with end-stage liver disease (ESLD) is complicated by several factors. OBJECTIVE: To develop a practical and relatively inexpensive method for estimating creatinine production and clearance in patients with ESLD. METHODS: Serum creatinine concentrations and urinary excretion of creatinine were measured in 27 patients with moderate-to-severe liver disease with the goal of developing equations to predict creatinine clearance from serum creatinine. Subjects were studied during an initial evaluation for a liver transplant program. Two 24 hour urine specimens were collected along with 3 serum samples over a 2 day evaluation period. Serum and urine creatinine concentrations were determined using both a modified Jaffé (autoanalyzer) method and an HPLC method. The data were analyzed using nonlinear mixed-effects modeling. RESULTS: Considering both statistical criteria and physiological conventions through allometric scaling theory, creatinine clearance (mL/min) in males can be estimated as (80/serum creatinine) x (actual body weight/70)0.75. For females, the same equation is valid, but the result is multiplied by 0.661. A simplified equation without the exponent is presented, along with equations that are appropriate when an HPLC assay is used for greater specificity. CONCLUSIONS: These equations offer potential for improved estimation of creatinine clearance in patients with liver impairment; however, they need further validation using an independent group of subjects.

Severe cellulitis/myositis caused by Stenotrophomonas maltophilia.

OBJECTIVE: To present a case of cellulitis/myositis due to Stenotrophomonas maltophilia in the absence of trauma and to discuss a potentially novel treatment option. CASE SUMMARY: A 57-year-old white man, having undergone an allogeneic bone marrow transplant, developed myositis with S. maltophilia of the left soleus muscle; there had been no trauma. Risk factors for infection included neutropenia, prolonged hospitalization and intensive care unit stay, and broad-spectrum antibiotic exposure. The affected area of muscle was resected and the patient successfully treated with trimethoprim/sulfamethoxazole (TMP/SMX), ticarcillin/clavulanate, and aztreonam. DISCUSSION: In severe myositis/cellulitis caused by S. maltophilia, TMP/SMX is considered the drug of choice. However, bacteriostatic agents such as TMP/SMX are less than ideal in neutropenic patients. The combination of ticarcillin/clavulanate plus aztreonam has been shown to improve activity in vitro against this organism compared with TMP/SMX. This is likely due to inhibition of the 2 beta-lactamases this organism produces by clavulanate and aztreonam. In our study of clinical isolates of S. maltophilia, this combination reduced the minimum inhibitory concentration at 90% by 128-fold and was synergistic against 10 of 12 isolates tested in time-kill analysis. CONCLUSIONS: S. maltophilia is emerging as an important pathogen in patients with compromised immunity, leading to severe infections that are difficult to treat. Based on in vitro synergy studied, we recommend considering ticarcillin/clavulanate plus aztreonam as a potential treatment option in immunocompromised patients with S. maltophilia infection.