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.

Acanthamoeba keratitis and contact lens disinfecting solutions.

OBJECTIVES: To report cases of culture-proved Acanthamoeba keratitis in Greece over a 10-year period and to evaluate the effectiveness of the commonly used commercial contact lens disinfecting systems in clinical cases of Acanthamoeba keratitis. MATERIAL AND METHODS: During the years 1994-2004, 45 contact lens wearers and 3 non-contact lens wearers presenting with symptoms and signs of keratitis underwent corneal sampling. The scrapings obtained were inoculated directly onto appropriate culture media for bacteria, fungi and Acanthamoeba. All proved positive for Acanthamoeba. The contact lenses and contact lens disinfecting solutions (16 one-step 3% hydrogen peroxide and 3 multipurpose solutions) of 19/45 patients with culture-proven Acanthamoeba keratitis were cultured for bacteria, fungi and Acanthamoeba. RESULTS: Acanthamoeba was isolated from contact lenses and contact lens disinfecting solutions in all 19 cases of Acanthamoeba keratitis studied. CONCLUSIONS: The main risk factor for corneal infection in contact lens wearers is the use of contact lens disinfecting systems ineffective at killing Acanthamoeba cysts and trophozoites, as well as bacteria and fungi. Improvement or development of new contact lens disinfecting systems by manufacturers is needed to prevent Acanthamoeba keratitis.

Genotyping of pathogenic Acanthamoebae isolated from clinical samples in Greece--report of a clinical isolate presenting T5 genotype.

Amoebae belonging to the genus Acanthamoeba are potentially pathogenic to humans, causing mainly amoebic keratitis. Pathogenic ability of the 15 known Acanthamoeba genotypes is under investigation. We report that four out of five cases of amoebic keratitis studied in Greece, present T4 sequence type, while the remaining one presents T5 sequence type (Acanthamoeba lenticulata), which is the second most frequent genotype found among environmental samples. Thus, it is confirmed, for the first time to our knowledge, that A. lenticulata can cause keratitis. However the reason that it is under represented in clinical samples compared to environmental ones is unknown.

Coinfection of Schistosoma mansoni and Strongyloides stercoralis in a patient with variceal bleeding.

We report a case of hepatosplenic schistosomiasis with portal hypertension and variceal bleeding in an immigrant patient from Egypt, coinfected with Strongyloides stercoralis. The diagnosis was based on the following: (a) identification of Schistosoma mansoni ova in the stools and colonic biopsy specimens, (b) portal hypertension and esophageal varices with normal liver function and the absence of hepatic cirrhosis stigmata, (c) history of migration from an endemic area and (d) ultrasonographic findings of spleen and liver enlargement, fibrosed portal tracts, and normal lobular architecture of liver parenchyma. Hepatosplenic schistosomiasis should be suspected in any patient from an endemic area who has splenomegaly, portal hypertension, and esophageal varices bleeding in the absence of stigmata of liver cirrhosis and hepatic insufficiency. Coinfection with S. stercoralis could be attributed to common epidemiological features of the parasites and the patient's habits.

Clinical efficacy of sulbactam/ampicillin in pediatric infections caused by ampicillin-resistant or penicillin-resistant organisms.

Twenty-three children two months to 11 years old were treated with sulbactam/ampicillin or sulbactam/penicillin. Eleven had urinary tract infections (UTI), eight had pus-forming cervical adenitis, and four had lobar pneumonia. Pathogens were isolated from 18 patients: Escherichia coli from 10, Staphylococcus aureus from seven, and Klebsiella pneumoniae from one. All isolates were resistant to ampicillin or penicillin alone. Sulbactam (50 mg/kg per day) plus ampicillin (1:2 or 1:3 ratio) or penicillin (1:1.2 or 1:1.8 ratio) was given by intravenous bolus injection at 6-hr intervals for four to 11 days (mean duration, nine days). All pathogens were eradicated during treatment. Two patients with UTI relapsed after completion of treatment; the isolates were resistant to the combination. Clinical response was rapid and consistent with bacteriologic findings. Twenty-two of 23 children had a favorable clinical response. No systemic or local adverse effects were recorded. One child had eosinophilia and another had neutropenia at the end of treatment. Four children had slight and transient increases in hepatic transaminases. These results indicate that sulbactam/ampicillin may prove safe and effective for the treatment of non-life-threatening pediatric infections.

Enterobacter sepsis in infants and children due to contaminated intravenous fluids.

Sixty-three cases of nosocomial sepsis occurring from April through October 1981, in a 500-bed pediatric hospital, were traced to bacterial contamination of intravenous fluid produced by a single manufacturer. Two species of uncommon blood stream pathogens, Enterobacter cloacae and Enterobacter agglomerans contaminated the fluid. Infections with these organisms might have contributed to the death of four patients; two who were immunosuppressed, one who was asplenic and one premature infant. Epidemiologic and laboratory investigations identified the site of contamination to be within the screw-caps of the bottles containing the intravenous fluid. Contamination occurred during insertion of the intravenous fluid administration set into the bottle. The "epidemic" terminated when the hospital discontinued the use of infusion fluids from that manufacturer. We conclude that intravenous fluids should be examined during outbreaks of nosocomial bacteremia due to unusual pathogens.