Preliminary gas chromatography with mass spectrometry determination of 3,5-dimethoxyphenol in biological specimens as evidence of taxus poisoning.

Taxus baccata is a widely distributed yew often associated with cases of fatal intoxication, which is related to the high amounts of cardiotoxic alkaloids, taxine A and taxine B, contained in its leaves. In this paper, a case of Taxus fatal poisoning, hypothesized by the forensic autopsy, has been confirmed by the application of both gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) techniques. A GC-MS method was used for the determination of the derivatized 3,5-dimethoxyphenol, a cyanogenic aglylactone considered as a marker of Taxus poisoning, being present in all species of Taxus. The detection by LC-MS-MS of taxine B and isotaxine B in the biological specimens confirmed the absorption of cardiotoxic alkaloids and allowed to established the cause of death as the ingestion of Taxus baccata leaves.

Capillary gas chromatographic determination of spermidine in diet integrators.

Biogenic polyamines, among which is spermidine (SPD, NH2-(CH2)4-NH-(CH2)3-NH2), are ubiquitous polycationic molecules that have a definitive role in many biological processes, such as nucleic acid metabolism, protein synthesis and cell growth. SPD is present in diet integrators because it seems to favour the hair growth. This work describes a capillary gas chromatographic (CGC) method for the quantitative determination of SPD in diet integrators using cadaverine internal standard (IS), a methyl siliconic capillary column and flame-ionization detector (FID). Diet tablets, containing SPD, are pulverized; an aliquot of powder is treated with an alkaline aqueous solution and added with IS. The suspension is extracted with diethyl ether containing ethyl chloroformate (ECF). The ether extracts, evaporated to dryness and reconstituted in ethyl acetate were analyzed in CGC/FID. Derivatives of polyamines with ECF were characterized in CGC/MS too. Validation has considered specificity, linearity, precision and accuracy of analytical method; this parameters are valid for the quantitative determination of SPD in diet integrators.

Etiology of children's diarrhea in Montevideo, Uruguay: associated pathogens and unusual isolates.

We studied microorganisms associated with infant diarrhea in a group of 256 children admitted to a public pediatric hospital in Montevideo, Uruguay. Diagnostic procedures were updated to optimize detection of potential pathogens, which were found in 63.8% of cases, and to be able to define their characteristics down to molecular or antigenic type. Coinfection with two or more agents was detected in more than one-third of positive studies. Escherichia coli enteric virotypes, especially enteropathogenic E. coli (EPEC), were shown to be prevalent. Rotavirus, Cryptosporidium, Campylobacter (mainly Campylobacter jejuni), and Shigella flexneri were also often identified. Enterotoxigenic E. coli, Salmonella, and Giardia lamblia were sporadically recognized. Unusual findings included two enteroinvasive E. coli strains, one Shigella dysenteriae 2 isolate, and a non-O:1 Vibrio cholerae culture. EPEC bacteria and S. flexneri (but not Salmonella) showed unusually frequent antimicrobial resistance, especially towards beta-lactam antibiotics, which is the subject of ongoing work.

Three-year assessment of methicillin-resistant Staphylococcus aureus clones in Latin America from 1996 to 1998.

Four hundred ninety-nine methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from 1996 to 1998 from 22 hospitals in five countries of Latin America-Argentina, Brazil, Chile, Uruguay and Mexico-were examined for antimicrobial susceptibility and clonal type in order to define the endemic clones in those hospitals. The hybridization of ClaI restriction digests with the mecA- and Tn554-specific DNA probes combined with pulsed-field gel electrophoresis of chromosomal SmaI digests (ClaI-mecA::ClaI-Tn554::PFGE clonal types) documented not only the predominance and persistence of the Brazilian clone (XI::B::B) in Brazil (97%) and Argentina (86%) but also its massive dissemination to Uruguay (100%). Moreover, a close relative of the Brazilian clone (XI::kappa::B) was highly represented in Chile (53%) together with a novel clone (47%) (II::E'::F) resistant to pencillin, oxacillin, ciprofloxacin, chloramphenicol, clindamycin, erythromycin, and gentamicin. A unique clonal type (I::NH::M) was detected in Mexico among pediatric isolates and was resistant to penicillin, oxacillin, and gentamicin only. This study clearly documented the very large capacity for geographic expansion and the persistence of the Brazilian clone, contributing not only to the increasing uniformity of the MRSA in South America but worldwide as well.

Determination of trimethoprim-sulfamethoxazole resistance in Streptococcus pneumoniae by using the E test with Mueller-Hinton agar supplemented with sheep or horse blood may be unreliable. The Pneumococcal Study Group.

An international, multicenter study compared trimethoprim-sulfamethoxazole MICs for 743 Streptococcus pneumoniae isolates (107 to 244 isolates per country) by E test, using Mueller-Hinton agar supplemented with 5% defibrinated horse blood or 5% defibrinated sheep blood, with MICs determined by the National Committee for Clinical Laboratory Standards broth microdilution reference method. Agreement within 1 log2 dilution and minor error rates were 69.3 and 15.5%, respectively, on sheep blood-supplemented agar and 76.9 and 13.6%, respectively, with horse blood as the supplement. Significant interlaboratory variability was observed. E test may not be a reliable method for determining the resistance of pneumococci to trimethoprim-sulfamethoxazole.

Capsular type distribution and susceptibility to antibiotics of Streptococcus pneumoniae clinical strains isolated from Uruguayan children with systemic infections. Pneumococcus Study Group.

Children under 24 months of age are at high risk for serious infection with Streptococcus pneumoniae but they do not elicit effective immune responses to the currently available capsular polysaccharide vaccines. A polysaccharide protein conjugated vaccine involving the most frequent types has become an urgent need. To produce such a vaccine for Latin America, information on type distribution is required. Recently, Uruguay was 1 of the 6 countries in Latin America where surveillance for invasive pneumococcal infections in children under the age of 5 years was carried out. Seventy percent of the 182 invasive S. pneumoniae isolates were recovered from patients under 24 months of age, and 19% were recovered from infants under 6 months. The 7 most frequent types were 14, 5, 1, 6B, 3, 7F, and 19A; representing 80% of invasive isolates. Twenty-one types were identified, 16 in pneumonia and 14 in meningitis. Resistance to penicillin increased during the study period, from 29% in 1994, to 40% in 1995-1996, mainly because of the spread of type 14 strains resistant to penicillin and trimethoprim/sulphamethoxazol (89% of resistant isolates). The high proportion of systemic pneumococcal infections recorded in patients under 24 months of age and the increasing resistance of these agents to first-choice antibiotics point to an urgent need for a capsular polysaccharide protein conjugated vaccine.