Determination of cycloserine in human plasma by high-performance liquid chromatography with fluorescence detection, using derivatization with p-benzoquinone.

A new method for determining cycloserine in plasma samples is described. This method is based on the derivatization of cycloserine with p-benzoquinone, a reaction that takes place at the same time as the process of plasma deproteinization due to the presence of ethanol as solvent in the solution of the derivatization reagent. Four derivatives are obtained from this reaction. The main derivative is well correlated with the cycloserine concentration. The ratio between the volumes of the plasma sample and the reagent solution is 1:2 for a p-benzoquinone concentration of 1000 microg/mL. Elution from a C18 column was isocratic, using a mobile phase containing (v/v) 85% aqueous 0.1% formic acid solution, and 15% (v/v) of a mixture of methanol and acetonitrile (1:1), with a flow-rate of 1 mL/min, at 25 degrees C. Determinations by fluorescence detection were achieved with excitation at 381 nm and emission at 450 nm, with a detection limit of 10 ng/mL for an injection volume of 5 microL. This method was validated and applied to the determination of cycloserine in blood plasma samples of several healthy volunteers.

Effect of viral preinfection upon cell adherence in some staphylococcus strains from specific infections or carriers.

The adherence of bacteria to eukaryote cells has been largely investigated as an essential step in the occurrence of bacterial infection. Some clinical and epidemiological studies have revealed the frequent association of certain viral infections with bacterial infections originating in the same ecological niche. Therefore, we investigated the effect of the viral preinfection (ADV4) of some cultivated cells (HEp-2 and IC.SK-27) upon the adherence of staphylococcus to these cells. The analysis of cell adherence within the mentioned conditions, estimated by flow cytometry, allowed of the following conclusions: 1. bacterial adherence to cultivated and virally preinfected cells is augmented by the viral preinfection, and its value on a given cell substrate may characterize a bacterial strain; 2. bacterial adherence to the investigated cell substrates does not correlate with the origin of the tested staphylococcus strains (infections or carriers) and some cell lines can differentiate bacterial strains depending upon the ecological niche or inside it.

[The demonstration of the production of "slime"--a marker of pathogenicity in coagulase-negative staphylococci]. / Evidentiera producerii de "slime"--marker de patogenitate pentru stafilococii coagulaza negativi.

The authors tested for "slime" elaboration 48 S. epidermidis s.s. strains; 24 of these strains were isolated from bloodstream infections and 24 from resident cutaneous microbiota. The semiquantitative method of Christensen was used for testing "slime" elaboration. The predictive value of the positive test of "slime" elaboration was 92% in this study.

[The antibiotic resistance of Staphylococcus aureus strains isolated in units with an elevated nosocomial risk and in outpatient facilities in 1995]. / Rezistenta la antibiotice a unor tulpini de Staphylococcus aureus izolate din unitati cu risc nosocomial ridicat si din ambulatorii în anul 1995.

Antibiotic susceptibility testing in 231 strains of S. aureus isolated from patients highly exposed to the nosocomial risk and from patients treated in ambulatories for staphylococcal infections revealed significant discrepancies in respect to the incidence of multiple resistant strains and dispersion of resistance phenotypes. MRSA incidence rose to 58-85% in hospital boards, that indicated an "alarm state" which requests the supply of the efficient antibiotic. The 27.18% of MRSA between the strains isolated in ambulatories points to the risk of spreading this strains abroad the community and into the hospital boards and requests the monitoring of the chemotherapy in such of health carry units and of the antibiotic "automedication".

[Staphylococcus saprophyticus isolated in blood cultures from normal-weight newborn infants with septic arthritis]. / Staphylococcus saprophyticus izolat din hemoculturi provenind de la nou-nascuti normoponderali cu artrite septice.

The paper deals with the identification of some Staphylococcus saprophyticus strains received by the Staphylococcus National Reference Centre, in the Cantacuzino Institute, Bucharest, Romania. The strains were isolated from blood cultures pre-elevated in a maternity in Bucharest from normoponderal newborns with septic arthritis. Recent data from literature concerning the infections caused by coagulase negative staphylococci in general, with special reference to those cause by S. saprophyticus are presented. The identification scheme used in the Cantacuzino Institute and the minimal microbiological diagnosis tests of S. saprophyticus recommended to the clinical laboratories by the International Society for the Taxonomy of Staphylococci and Micrococci are also described.

Susceptibility to bacteriophages of Staphylococcus aureus strains received at the National Reference Centre for Staphylococci in Romania 1978-1992.

In order to determine the distribution among lytic groups of Staphylococcus aureus strains circulating in Romania 18,539 strains were phage typed in the National Reference Centre for Staphylococci between 1978 and 1992. Strains susceptible to group II phages prevailed, representing 28.28% of all phage typed strains. The distribution on lytic groups differed in terms of the type of the clinical isolate. The results are statistically analysed and compared with those obtained in Romania by Popovici et al. between 1966 and 1978 as well as with those reported for other geographical areas by other authors.