Comparison of synonymous codon distribution patterns of bacteriophage and host genomes.
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Synonymous codon usage patterns of bacteriophage and host genomes were compared. Two indexes, G + C base composition of a gene (fgc) and fraction of translationally optimal codons of the gene (fop), were used in the comparison. Synonymous codon usage data of all the coding sequences on a genome are represented as a cloud of points in the plane of fop vs. fgc. The Escherichia coli coding sequences appear to exhibit two phases, "rising" and "flat" phases. Genes that are essential for survival and are thought to be native are located in the flat phase, while foreign-type genes from prophages and transposons are found in the rising phase with a slope of nearly unity in the fgc vs. fop plot. Synonymous codon distribution patterns of genes from temperate phages P4, P2, N15 and lambda are similar to the pattern of E. coli rising phase genes. In contrast, genes from the virulent phage T7 or T4, for which a phage-encoded DNA polymerase is identified, fall in a linear curve with a slope of nearly zero in the fop vs. fgc plane. These results may suggest that the G + C contents for T7, T4 and E. coli flat phase genes are subject to the directional mutation pressure and are determined by the DNA polymerase used in the replication. There is significant variation in the fop values of the phage genes, suggesting an adjustment to gene expression level. Similar analyses of codon distribution patterns were carried out for Haemophilus influenzae, Bacillus subtilis, Mycobacterium tuberculosis and their phages with complete genomic sequences available. (+info)
Ketolide treatment of Haemophilus influenzae experimental pneumonia.
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The MICs of HMR 3004 and HMR 3647 at which 90% of beta-lactamase-producing Haemophilus influenzae isolates were inhibited were 4 and 2 micrograms/ml, respectively. Both HMR 3004 and HMR 3647 were active against beta-lactamase-producing H. influenzae in a murine model of experimental pneumonia. As assessed by pulmonary clearance of H. influenzae, HMR 3004 was more effective (P < 0.05) than was azithromycin, ciprofloxacin, clarithromycin, erythromycin A, pristinamycin, or HMR 3647 in this model. (+info)
Evolutionary relationships among diverse bacteriophages and prophages: all the world's a phage.
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We report DNA and predicted protein sequence similarities, implying homology, among genes of double-stranded DNA (dsDNA) bacteriophages and prophages spanning a broad phylogenetic range of host bacteria. The sequence matches reported here establish genetic connections, not always direct, among the lambdoid phages of Escherichia coli, phage phiC31 of Streptomyces, phages of Mycobacterium, a previously unrecognized cryptic prophage, phiflu, in the Haemophilus influenzae genome, and two small prophage-like elements, phiRv1 and phiRv2, in the genome of Mycobacterium tuberculosis. The results imply that these phage genes, and very possibly all of the dsDNA tailed phages, share common ancestry. We propose a model for the genetic structure and dynamics of the global phage population in which all dsDNA phage genomes are mosaics with access, by horizontal exchange, to a large common genetic pool but in which access to the gene pool is not uniform for all phage. (+info)
Comparative activity of quinupristin/dalfopristin and RPR 106972 and the effect of medium on in-vitro test results.
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Quinupristin/dalfopristin and RPR 106972 were active in vitro against a wide range of aerobic Gram-positive organisms including Enterococcus faecium. However, most isolates of Enterococcus faecalis were resistant or of intermediate sensitivity. Against Staphylococcus aureus quinupristin/dalfopristin was more active but for all other species the range of activity of the two drugs was the same or RPR 106972 was more active. RPR 106972 was also more active against the respiratory pathogens Haemophilus influenzae and Moraxella catarrhalis. Quinupristin/dalfopristin MICs for isolates of H. influenzae (1-8 mg/L) clustered around the breakpoint. There were differences in the quality of growth, but little difference in MICs or zone diameters was obtained on three different media: Mueller-Hinton (MHA), Iso-Sensitest (ISA), and Diagnostic Sensitivity Test (DST) agars. The addition of blood to the medium increased MICs 2- to 4-fold, with MHA showing the greatest increase, and reduced zone diameters around quinupristin/dalfopristin discs by 3-4 mm, with the greatest effect on ISA. (+info)
Candidate bacterial conditions.
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This article provides background information on bacterial diseases and discusses those that are candidates for elimination or eradication. Only one disease, neonatal tetanus, is a strong candidate for elimination. Others, including Haemophilus influenzae b infection, leprosy, diphtheria, pertussis, tuberculosis, meningococcal disease, congenital syphilis, trachoma and syphilis are important causes of morbidity and mortality in industrialized and developing countries. For all these diseases, eradication/elimination is not likely because of the characteristics of the disease and limitations in the interventions. (+info)
Antibiotic strategies for developing countries: experience with acute respiratory tract infections in Pakistan.
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The Pakistan program for control of acute respiratory tract infections (ARIs) adopted the standard ARI-case-management strategy of the World Health Organization and recommended co-trimoxazole for the management of nonsevere pneumonia. Reports in that country of high in vitro antimicrobial resistance of Streptococcus pneumoniae and Haemophilus influenzae to co-trimoxazole prompted the program to reevaluate its treatment policy. Two community-based studies during 1991-1993 showed in vivo efficacy of co-trimoxazole in 92% and 91% of children with nonsevere pneumonia. A third double-blind trial showed co-trimoxazole and oral amoxicillin to be equally effective in vivo in cases of nonsevere pneumonia, despite high in vitro resistance. Country-wide surveillance from 1991 to 1994 revealed 78.3%-79.9% in vitro resistance to co-trimoxazole among S. pneumoniae isolates and 59.5%-61.0% among H. influenzae isolates. Co-trimoxazole is still recommended by the Pakistan ARI control program. The fact that amoxicillin is three times more expensive and must be administered more frequently is a big impediment to recommending it as a first-line drug for nonsevere pneumonia. (+info)
Outer membrane protein profiles of paired nasopharyngeal and middle ear isolates of nontypable Haemophilus influenzae from Mexican children with acute otitis media.
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We studied nontypable Haemophilus influenzae (NTHi) isolates from simultaneous cultures of nasopharyngeal exudates (NEs) and middle ear fluids (MEFs) obtained by tympanocentesis from 57 children with acute otitis media (AOM). Preparations of outer membrane proteins (OMPs) from 14 pairs of NTHi strains recovered from NEs and MEFs from 10 children with unilateral AOM and four with bilateral AOM were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The NTHi subtypes were determined by comparing the OMP profiles of the isolated strains with those of eight reference NTHi subtypes. Of the 14 pairs, 10 (71%) were identical, and one (8%) was different; three strains isolated from NEs (21%) did not correspond to any of the reference subtypes (nonsubtypable). Subtypes 4, 6, 5, 3, and 8 were isolated in the present study, thereby showing that their distribution is similar to that of subtypes isolated from children with AOM in the United States and suggesting that common otogenic strains are widely distributed in North America. (+info)
Identification of Haemophilus influenzae Rd transformation genes using cassette mutagenesis.
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Genes required for natural transformation of Haemophilus influenzae Rd were identified by a cassette mutagenesis protocol consisting of the following steps: random insertional mutagenesis, phenotypic screening, sequencing of genome sequence tags from the DNA flanking the insertion in the selected mutants and comparison of genome sequence tags to genomic sequence data. The cassette mutagenesis screen for transformation genes resulted in five distinct mutant classes, two of which have been identified in previous studies. Insertions in the three newly identified loci interrupted genes with predicted protein products homologous to a type IV pilin-like protein biogenesis operon, drug-efflux transporters and a phospholipid-biosynthesis enzyme. The most significant finding of this screen is the requirement for type IV pilin-like proteins in genetic transformation of H. influenzae. These surface structures are utilized for DNA uptake in a number of Gram-positive and Gram-negative bacteria, and appear to be the common component among the systems for DNA binding. (+info)