The Effects of Fasting and Massive Diarrhea on Absorption of Enteral Vancomycin in Critically Ill Patients: A Retrospective Observational Study

Purpose

Although vancomycin (VCM) is not absorbed from healthy intestinal mucosa, elevations in the serum VCM concentrations have been reported in some cases. The aims of this study are to evaluate the necessity of therapeutic drug monitoring (TDM) during enteral VCM administration in critically ill patients.

Materials and methods

In this retrospective study, we enrolled 19 patients admitted to our intensive care unit who were treated with enteral VCM from December 2006 to January 2014. Clinical factors were compared between two groups: Group E whose serum concentrations were detectable, and Group N whose concentrations were below the detection limit of the VCM assay.

Results

Group E comprises 7 patients, and Group N comprises 12 patients. The fasting duration in Group E was significantly longer compared with that in Group N (17 vs. 8 days, p = 0.023). Furthermore, there was a significant correlation between the serum VCM concentrations and the fasting duration (r = 0.79, p < 0.0001), and the amount of diarrhea (r = 0.46, p = 0.046). No difference was observed in the amount of diarrhea at the time of TDM (Group E; 1,850 mL vs. Group N; 210 mL, p = 0.055) and in the Sequential Organ Failure Assessment subscore for the renal system at the time of TDM (Group E; 4.0 vs. Group N; 1.5, p = 0.068).

Conclusion

Long durations of fasting and massive diarrhea were associated with elevations in the serum VCM concentrations, which suggested that TDM might be necessary during enteral VCM administration in critically ill patients.

Trial registration

UMIN Clinical Trials Registry identifier UMIN000016955.

Oncogenic signaling by Kit tyrosine kinase occurs selectively on the Golgi apparatus in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are caused by gain-of-function mutations in the Kit receptor tyrosine kinase. Most primary GIST patients respond to the Kit inhibitor imatinib, but this drug often becomes ineffective because of secondary mutations in the Kit kinase domain. The characteristic intracellular accumulation of imatinib-sensitive and -resistant Kit protein is well documented, but its relationship to oncogenic signaling remains unknown. Here, we show that in cancer tissue from primary GIST patients as well as in cell lines, mutant Kit accumulates on the Golgi apparatus, whereas normal Kit localizes to the plasma membrane (PM). In imatinib-resistant GIST with a secondary Kit mutation, Kit localizes predominantly on the Golgi apparatus. Both imatinib-sensitive and imatinib-resistant Kit (Kit(mut)) become fully auto-phosphorylated only on the Golgi and only if in a complex-glycosylated form. Kit(mut) accumulates on the Golgi during the early secretory pathway, but not after endocytosis. The aberrant kinase activity of Kit(mut) prevents its export from the Golgi to the PM. Furthermore, Kit(mut) on the Golgi signals and activates the phosphatidylinositol 3-kinase–Akt (PI3K–Akt) pathway, signal transducer and activator of transcription 5 (STAT5), and the Mek–Erk pathway. Blocking the biosynthetic transport of Kit(mut) to the Golgi from the endoplasmic reticulum inhibits oncogenic signaling. PM localization of Kit(mut) is not required for its signaling. Activation of Src-family tyrosine kinases on the Golgi is essential for oncogenic Kit signaling. These results suggest that the Golgi apparatus serves as a platform for oncogenic Kit signaling. Our study demonstrates that Kit(mut)’s pathogenicity is related to its mis-localization, and may offer a new strategy for treating imatinib-resistant GISTs.

Veno-arterial extracorporeal membrane oxygenation for Streptococcus pyogenes toxic shock syndrome in pregnancy

Streptococcal toxic shock syndrome (STSS), an invasive Streptococcus pyogenes (Group A streptococcus) infection with hypotension and multiple organ failure, is quite rare in pregnancy but is characterized by rapid disease progression and high fatality rates. We present a case of STSS with infection-induced cardiac dysfunction in a pregnant woman who was treated with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). A 24-year-old multiparous woman in the third trimester had early symptoms of high fever and diarrhea 1 day prior to admission to the hospital emergency department. On admission, she had multiple organ failure including circulatory failure. Due to fetal distress, emergency Cesarean section was carried out and transferred to intensive care units. She had refractory circulatory failure with depressed myocardial contractility with progressive multiple organ failure, despite receiving significant hemodynamic supports including high-dose catecholamine. Thus, VA-ECMO was initiated 18 h after intensive care unit admission. Consequently, ECMO provided extra time to recover from infection and myocardial depression. She was successfully weaned from VA-ECMO on day 7 and was discharged home on day 53. VA-ECMO can be a therapeutic option for refractory circulatory failure with significant myocardial depression in STSS.