Investigation of an outbreak of gram-negative bacteremia among hematology-oncology outpatients.

OBJECTIVE: To identify risk factors associated with an outbreak of gram-negative bacteremia (GNB). SETTING: A university hospital. PATIENTS: Hematology-oncology outpatients. DESIGN: Retrospective case-control study. RESULTS: Thirty-eight patients developed GNB; 13 patients experienced more than one episode, and eight blood cultures grew more than one gram-negative organism. The most frequently isolated organisms were Stenotrophomonas maltophilia, Klebsiella pneumoniae, Acinetobacter baumannii, and Acinetobacter johnsonii. When the GNB patients (cases) were compared with randomly selected hematology-oncology patients (controls), central venous catheter (CVC) self-care (71% vs 39%; P=.02), and duration of recent hospital stay (median, 15 vs 4 days; P=.01) were identified as risk factors. In a logistic regression model, duration of recent hospital stay was the only risk factor significantly associated with GNB (odds ratio, 1.05; 95% confidence interval, 1.01-1.08; P<.02). CONCLUSIONS: Hematology-oncology patients providing their own CVC care who have recently been hospitalized for more than 2 weeks may be at increased risk of GNB. CVCs should be protected from possible environmental contamination in hematologyoncology patients. Patients providing their own CVC care should undergo continued rigorous education regarding proper CVC care.

Concentrations of biotin metabolites in human milk.

Because estimates of the biotin requirement for infants currently are based on the biotin concentration in human milk, we sought to determine whether inactive biotin metabolites are present. Samples were collected for 7 weeks post partum from 15 healthy women. Biotin and the inactive metabolites bisnorbiotin and biotin sulfoxide were measured by means of a high-performance liquid chromatography avidin-binding assay. At 8 days post partum the proportion of biotin was 44%, bisnorbiotin 48%, and biotin sulfoxide 8%. Although biotin content increased post partum (p < 0.003), the metabolites remained an important portion of the total providing evidence that accurate measurement of biotin in human milk requires an assay that is specific for biotin.

Biotin status assessed longitudinally in pregnant women.

This study assessed biotin nutritional status longitudinally during pregnancy as judged by urinary excretion of biotin and biotin metabolites and by serum concentration of biotin. 3-Hydroxyisovaleric acid excretion was also assessed because increased excretion of that acid reflects decreased tissue activity of the biotin-dependent enzyme, methylcrotonyl-CoA carboxylase. Thirteen women provided untimed urine samples during both early and late pregnancy. Twelve nonpregnant women served as controls. Biotin and metabolites were determined by a combined HPLC/avidin-binding assay. 3-Hydroxyisovaleric acid was determined by gas chromatography/mass spectrophotometry. Significance of changes from early to late pregnancy was tested by paired t test; to compare nonpregnant controls with early and late pregnancy, ANOVA was used. During early pregnancy, biotin excretion was not significantly different than controls; however, 3-hydroxyisovaleric acid excretion was significantly increased relative to controls (P < 0.0001) and was greater than the upper limit of normal in 9 of 13 women. From early to late pregnancy, biotin excretion decreased in 10 of 13 women (P < 0.01); by late pregnancy, biotin excretion was less than normal in six women. During late pregnancy, 3-hydroxyisovaleric acid remained significantly increased relative to controls (P < 0.0001). Serum concentrations of biotin were significantly greater than those of controls during early pregnancy (P < 0.0001) and decreased in each woman from early to late pregnancy (P < 0.0001). These data provide evidence that biotin status decreases during pregnancy.