Browsing by Subject "Bacterial Infections"

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    Gentamicin pharmacokinetics and pharmacodynamics during short-daily hemodialysis
    (S. Karger AG, 2012) Decker, Brian S.; Mohamed, Ahmed N.; Chambers, Mary; Kraus, Michael A.; Moe, Sharon M.; Sowinski, Kevin M.; Department of Medicine, IU School of Medicine
    BACKGROUND/AIMS: Gentamicin pharmacokinetics have not been described in patients undergoing short-daily hemodialysis (SDHD). The aim of this study is to describe gentamicin pharmacokinetics and dialytic clearance (Cl(dial)) in SDHD patients and simulate gentamicin exposure after six dosing regimens to help guide future dosing. METHODS: Six anuric patients undergoing SDHD were enrolled. Patients received intravenous infusion of 2 mg/kg gentamicin on day 1 after the first HD session followed by HD sessions on days 2, 3, and 4. Blood samples for determination of gentamicin concentrations were serially collected. Gentamicin pharmacokinetic parameters and Cl(dial) and interindividual variability terms (IIV) were estimated using NONMEM VII. Influence of patient weight on systemic clearance (Cl(s)) and central volume of distribution (V(c)) and influence of urea removal estimates on Cl(dial) were assessed. The model was used to simulate gentamicin concentrations after six dosing regimens including pre- and postdialysis as well as daily and every-other-day dosing. RESULTS: A two-compartment model with first-order elimination from central compartment described gentamicin pharmacokinetics. Population estimates for Cl(s) and Cl(dial) were 7.6 and 134 ml/min, respectively. Patient weight was statistically significantly associated with Cl(s) and V(c). Predialysis every-other-day regimens were as effective (C(max) ≥8 mg/l and AUC(48 h) ≥140 mg·h/l) and less toxic (C(min) <2 mg/l and AUC(48 h) <240 mg·h/l) than postdialysis regimens. CONCLUSIONS: Estimated gentamicin Cl(dial) is higher than previous estimates with thrice-weekly regimens. Predialysis every-other-day dosing may be recommended during SDHD.
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    Similarities and seasonal variations in bacterial communities from the blood of rodents and from their flea vectors
    (Nature Publishing Group, 2015-07) Cohen, Carmit; Toh, Evelyn; Munro, Daniel; Dong, Qunfeng; Hawlena, Hadas; Department of Microbiology and Immunology, IU School of Medicine
    Vector-borne microbes are subject to the ecological constraints of two distinct microenvironments: that in the arthropod vector and that in the blood of its vertebrate host. Because the structure of bacterial communities in these two microenvironments may substantially affect the abundance of vector-borne microbes, it is important to understand the relationship between bacterial communities in both microenvironments and the determinants that shape them. We used pyrosequencing analyses to compare the structure of bacterial communities in Synosternus cleopatrae fleas and in the blood of their Gerbillus andersoni hosts. We also monitored the interindividual and seasonal variability in these bacterial communities by sampling the same individual wild rodents during the spring and again during the summer. We show that the bacterial communities in each sample type (blood, female flea or male flea) had a similar phylotype composition among host individuals, but exhibited seasonal variability that was not directly associated with host characteristics. The structure of bacterial communities in male fleas and in the blood of their rodent hosts was remarkably similar and was dominated by flea-borne Bartonella and Mycoplasma phylotypes. A lower abundance of flea-borne bacteria and the presence of Wolbachia phylotypes distinguished bacterial communities in female fleas from those in male fleas and in rodent blood. These results suggest that the overall abundance of a certain vector-borne microbe is more likely to be determined by the abundance of endosymbiotic bacteria in the vector, abundance of other vector-borne microbes co-occurring in the vector and in the host blood and by seasonal changes, than by host characteristics.