Serum bactericidal activity of three different dosing regimens of colistin with implications for optimum clinical use.

Although colistin methanesulfonate (CMS) has been used extensively in critically ill patients infected with multidrug-resistant organisms, the optimum dosing regimen remains to be determined. Herein, we examined the pharmacokinetics of three different dosing regimens of CMS, 3 million units every 8 h (regimen A), 4.5 million units every 12 h (regimen B), 9 million units every 24 h (regimen C) and evaluated the bactericidal activity of serum containing various concentrations of colistin against Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 1 microg/ml. the means +/- SE serum C(max )of colistin for regimens A, B, and C were 3.34+/-0.35, 2.98+/-0.27, and 5.63+/-0.87 microg/ml, respectively. All serum samples containing colistin >4 microg/ml (serum concentration/MIC >4) eliminated P. aeruginosa whereas only 40% of samples containing colistin <4 microg/ml resulted in complete bacterial killing. these findings indicate that the currently used dosing regimens might not provide the most effective therapy with CMS and justify administering larger dosages in longer intervals.

Molecular epidemiology of hepatitis C virus (HCV) in Greece: temporal trends in HCV genotype-specific incidence and molecular characterization of genotype 4 isolates.

This study aimed to estimate the overall HCV genotype distribution and to reconstruct the HCV genotype-specific incidence in Greece during the recent decades. It also focused at the identification of genotype 4 subtype variability in Greek isolates. A total of 1686 chronically infected HCV patients with detectable serum HCV RNA by RT-PCR, belonging to different risk groups were studied. Amplified products from the 5'-noncoding region were typed using a commercially available assay based on the reverse hybridization principle. The HCV genotype-specific incidence was estimated using a previously described back calculation method. HCV genotype 1 was the most prevalent (46.9%) followed by genotype 3 (28.1%), 4 (13.2%), 2 (6.9%) and 5 (0.4%). A high prevalence of genotype 1 (66.3%) in haemophilia patients was recorded whereas HCV genotype 3 was found mainly among patients infected by I.V. drug use (58.2%). Data on the temporal patterns of HCV genotype-specific incidence in Greece revealed a moderate increase (1.3-1.6 times) for genotypes 1 and 4, and a decrease (1.5 times) for genotype 2 from 1970 to 1990, whereas there was a sharp (13-fold) increase for genotype 3. The molecular characterization of 41 genotype 4 HCV isolates belonging to various risk groups revealed that, subtype 4a was the most frequently detected (78%). Phylogenetic comparison of the Greek 4a isolates with all HCV-4a isolates reported worldwide so far revealed a topology which does not discriminate Greek isolates from the others. HCV-4 does not represent a recent introduction in Greece.

The effect of adherence to therapy on sustained response in daily or three times a week interferon alpha-2b plus ribavirin treatment of naive and nonresponder chronic hepatitis C patients.

The aim was to demonstrate adherence to treatment has been suggested to enhance rates of sustained response in patients with hepatitis C. In this study, we evaluated the effect of drug dosage reduction or the duration of the expected therapy in patients treated with interferon (IFN)-alpha2b plus ribavirin. Virologic response rates were re-analysed according to compliance to therapy in (i) 301 naive and (ii) 142 nonresponders to previous IFN therapy treated with either IFN 5 MU TIW for 8 weeks followed by IFN 3 MU TIW for 40 weeks plus ribavirin or IFN 3 MU QD for 16 weeks followed by IFN 3 MU TIW for 24 weeks plus ribavirin. Patients were separated into those who adhered to > or =80% of their intended treatment schedule (dose of both drugs and duration) and those who did not. Compliance to treatment resulted in significantly higher response rates in both groups of patients: 43.93% compared with 6.90% of noncompliant naive patients and 30.77% compared with 10.53% of nonresponder patients. Compliance to treatment was found to have a similar effect when the results were analysed according to HCV genotype. Our findings suggest that compliance to treatment for > or =80% of the intended treatment schedule results in significantly higher sustained response rates in both naive and nonresponder patients. Consequently, every effort should be made to improve patient adherence to therapy.

Antibodies against hepatitis C virus among renal transplant patients in Greece.

To evaluate the prevalence of hepatitis C virus (HCV) infection in Greek renal transplant (RT) patients and its association with abnormal liver function tests (LFTs), serum anti-HCV was determined (Ortho-ELISA test system) in 206 RT and 245 haemodialysis patients (HD) as controls. The prevalence (10.2%) of anti-HCV in RT patients was significantly higher (P < 0.0001) than in the Greek general population (0.7%) and lower (P < 0.0001) than in the HD patients (23.8%), and was not related to the patients' age, post-transplant time or pre-transplant HD time. None of the anti-HCV RT patients was HBsAg+, whereas 13 (62%) and 12 (57%) of them were anti-HBsAg+ and anti-HBc+, respectively. The incidence of abnormal LFTs in anti-HCV+ HBsAg- and anti-HCV- HBsAg+ RT patients was similar. Our findings indicate that: (a) the prevalence of serum anti-HCV in the Greek RT population is high, although considerably lower than in HD pts; (b) anti-HCV+ RT patients have a high incidence of abnormal LFTs, comparable to that seen in HBsAg+ RT patients; and (c) in a substantial proportion of anti-HCV+ RT patients there is evidence of previous HBV infection.