Laboratory diagnosis of central nervous system infections with herpes simplex virus by PCR performed with cerebrospinal fluid specimens.

Until recently, the laboratory diagnosis of central nervous system (CNS) infections with herpes simplex virus (HSV) has been limited by poor sensitivity and/or specificity. We assessed the diagnostic utility of PCR for detection of HSV in over 2,100 specimens referred to the Mayo Clinic from August 1993 to May 1996. DNA extracted from cerebrospinal fluid (CSF) samples with IsoQuick was amplified by PCR with oligonucleotide primers directed to the DNA polymerase gene of HSV, yielding a 290-bp amplicon. HSV DNA was detected in 150 (135 by gel electrophoresis, 15 by Southern blotting only) of 2,106 (7.1%) specimens. PCR-positive CNS disease occurred in patients ranging in age from 13 days to 89 years; 59% of the cases occurred in patients between the ages of 30 and 69, and 21 (14%) of the patients were infants. Genotype analysis was not routinely performed; however, amplification of a 335-bp product within the thymidine kinase gene of HSV revealed 13 positions within a span of 80 nucleotides that accurately identified the two serotypes of the virus according to 14 reference strains. We conclude that PCR detection of HSV DNA in CSF specimens should be considered an emerging "gold standard" for the laboratory diagnosis of CNS infections with this virus.

Leclercia adecarboxylata infections: case report and review.

Leclercia adecarboxylata has been rarely isolated from environmental and clinical specimens. On review of the world literature, we found two reports of L. adecarboxylata infection: one report described a patient with hepatic cirrhosis, and the other described a child dependent on total parenteral nutrition. L. adecarboxylata was isolated from five infected patients who were evaluated at our institution. Three patients had lower-extremity wound infections in which L. adecarboxylata was part of a mixed microbial growth. One patient had pneumonia due to multiple bacteria, including L. adecarboxylata, which were isolated from sputum. L. adecarboxylata was isolated from the blood of one patient with neutropenia and from the blood of the two patients reported in the literature. All patients except one had fever and leukocytosis. L. adecarboxylata isolates were susceptible to all the antimicrobials tested. L. adecarboxylata is most frequently isolated as part of a mixed microbial growth. Its role in these infections is not clear. However, the organism caused bacteremia in three patients.

The esg locus of Myxococcus xanthus encodes the E1 alpha and E1 beta subunits of a branched-chain keto acid dehydrogenase.

The esg locus of Myxococcus xanthus appears to control the production of a signal that must be transmitted between cells for the completion of multicellular development. DNA sequence analysis suggested that the esg locus encodes the E1 decarboxylase (composed of E1 alpha and E1 beta subunits) of a branched-chain keto acid dehydrogenase (BCKAD) that is involved in branched-chain amino acid (BCAA) metabolism. The properties of an esg::Tn5 insertion mutant supported this conclusion. These properties include: (i) the growth yield of the mutant was reduced with increasing concentrations of the BCAAs in the medium while the growth yield of wild-type cells increased, (ii) mutant extracts were deficient in BCKAD activity, and (iii) growth of the mutant in media with short branched-chain fatty acids related to the expected products of the BCKAD helped to correct the mutant defects in growth, pigmentation and development. The esg BCKAD appears to be involved in the synthesis of long branched-chain fatty acids since the mutant contained reduced levels of this class of compounds. Our results are consistent with a model in which the esg-encoded enzyme is involved in the synthesis of branched-chain fatty acids during vegetative growth, and these compounds are used later in cell-cell signalling during development.