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Streptococcus mitis is the closest relative of the major human pathogen S. pneumoniae. The 2,15 Mb sequence of the Streptococcus mitis B6 chromosome, an unusually high-level beta-lactam resistant and multiple antibiotic resistant strain, has now been determined to encode 2100 genes. The accessory genome is estimated to represent over 40%, including 75 mostly novel transposases and IS, the prophage phiB6 and another seven phage related regions. Tetracycline resistance mediated by Tn5801, and an unusual and large gene cluster containing three aminoglycoside resistance determinants have not been described in other Streptococcus spp. Comparative genomic analyses including hybridization experiments on a S. mitis B6 specific microarray reveal that individual S. mitis strains are almost as distantly related to the B6 strain as S. pneumoniae. Both species share a core of over 900 genes. Most proteins described as pneumococcal virulence factors are present in S. mitis B6, but the three choline binding proteins PcpA, PspA and PspC, and three gene clusters containing the hyaluronidase gene, ply and lytA, and the capsular genes are absent in S. mitis B6 and other S. mitis as well and confirm their importance for the pathogenetic potential of S. pneumoniae. Despite the close relatedness between the two species, the S. mitis B6 genome reveals a striking X-alignment when compared with S. pneumoniae.

The polysaccharide capsule of Streptococcus pneumoniae is one of the most important virulence factors responsible for human infections and in mouse infection models as well. Larvae of Manduca sexta were used as an alternative animal model in order to test the impact of the pneumococcal capsule on virulence in the insect host. The unencapsulated S. pneumoniae strain R6 was able to cause disease and induce killing in the larvae, and similar results were obtained with related commensal species. However, using the same dose of S. pneumoniae, encapsulated strains including the type 2 D39 strain, the progenitor of R6, and genetically unrelated S. pneumoniae strains of serotype 2, 4, 6B, 23F and 19A, all had increased virulence potential compared to the R6 strain. Between 20 and 70% of the larvae were affected after 96 h compared to 12% observed with R6. Two type 6B S. pneumoniae strains were more virulent compared to the other strains. S. pneumoniae R6 transformants producing the type 6B capsule showed a similar elevated disease potential, confirming the contribution of the pneumococcal polysaccharide capsule to virulence in M. sexta.

The peptide SpiP of Streptococcus pneumoniae regulates the induction of a complex signal transduction system spiR1spiR2spiH. Distinct alleles of spiP and the receptor histidine protein kinase gene spiH were recognized in different pneumococcal clones. The spi system in strain KNR7/87 is adjacent to a bacteriocin gene cluster encoding putative double glycine-type bacteriocins, immunity proteins, and translocator proteins. A direct repeat element upstream of the spiR1 promoter and another three potential transcription start sites within the bacteriocin cluster indicate that SpiP functions as an inducing peptide for bacteriocin synthesis in S. pneumoniae.

Abstract The peptide SpiP of Streptococcus pneumoniae regulates the induction of a complex signal transduction system spiR1spiR2spiH. Distinct alleles of spiP and the receptor histidine protein kinase gene spiH were recognized in different pneumococcal clones. The spi system in strain KNR7/87 is adjacent to a bacteriocin gene cluster encoding putative double glycine-type bacteriocins, immunity proteins, and translocator proteins. A direct repeat element upstream of the spiR1 promoter and another three potential transcription start sites within the bacteriocin cluster indicate that SpiP functions as an inducing peptide for bacteriocin synthesis in S. pneumoniae.

The genome sequences of two strains of Streptococcus pneumoniae, one of the major human pathogens, are currently available: that of the nonencapsulated laboratory strain R6, the origin of which dates back to the early 20th century, and of the serotype 4 TIGR strain isolated recently. The two genomes are not only different in size (2 versus 2.16Mb) but differ also by approximately 10% of their genes, many of which being organized in large clusters. Their strain-specific genes and gene clusters are described here. The R6 genome contains 69kb organized in six large regions that are absent from the TIGR strain, which in turn contains an extra 157kb in twelve clusters compared to R6. In addition, the TIGR strain contains 13 clusters of 4kb and larger that are not shared by a variety of genetically different S. pneumoniae strains. Many regions bear signs of gene transfer events such as the presence of insertion sequences, transposable elements, and putative site-specific integrases/recombinases. Three strain-specific regions are devoted to genes encoding proteins with the cell wall anchor motif LPXTG which are important for the interaction with host cells and appear to be highly variable, similar to cell wall-associated choline-binding proteins.

Penicillin resistance in pneumococci is mediated by modified penicillin-binding proteins (PBPs) that have decreased affinity to β-lactams. In high-level penicillin-resistant transformants of the laboratory strain Streptococcus pneumoniae R6 containing various combinations of low-affinity PBPs, disruption of the fib locus results in a collapse of PBP-mediated resistance. In addition, crosslinked muropeptides are highly reduced. The fib operon consists of two genes, fibA and fibB, homologous to Staphylococcus aureus femA/ B which are also required for expression of methicillin resistance in this organism. FibA and FibB belong to a family of proteins of Gram-positive bacteria involved in the formation of interpeptide bridges, thus representing interesting new targets for antimicrobial compounds for this group of pathogens.

Abstract Penicillin resistance in pneumococci is mediated by modified penicillin-binding proteins (PBPs) that have decreased affinity to β-lactams. In high-level penicillin-resistant transformants of the laboratory strain Streptococcus pneumoniae R6 containing various combinations of low-affinity PBPs, disruption of the fib locus results in a collapse of PBP-mediated resistance. In addition, crosslinked muropeptides are highly reduced. The fib operon consists of two genes, fibA and fibB, homologous to Staphylococcus aureus femA/B which are also required for expression of methicillin resistance in this organism. FibA and FibB belong to a family of proteins of Gram-positive bacteria involved in the formation of interpeptide bridges, thus representing interesting new targets for antimicrobial compounds for this group of pathogens.

Highly penicillin- and cephalosporin-resistant Streptococcus mitis and Streptococcus oralis were isolated in Spain, Hungary, and Berlin. With chromosomal DNA of these strains, resistant transformants of Streptococcus pneumoniae were obtained that expressed low-affinity variants of penicillin- binding proteins (PBPs) 2x, 1a, 2a, and 2b in different combinations, depending on the selective conditions. The transformants had cefotaxime MICs of up to 6 µg/mL, and those with a low-affinity PBP 2b were highly deficient in penicillin-induced lysis. Sequence analysis of the pbp2x genes confirmed the presence of a global gene pool of penicillin resistance determinants shared by commensal and pathogenic streptococci.

A total of 320 horses were studied in this paper, both male and female, between two and 17 years of age, which were used for traction of wagons in the urban area of the municipality of Londrina (PR). These animals were kept, after their daily work, in abandoned areas or plots, in the outskirts of the urban area of the city. When these animals were attended by the veterinarians, between 1996 and 2005, none of them presented symptoms suggesting leptospirosis. The most frequent reasons for the visit were loss of weight, unwillingness for work, parasitism, laminess, and wounds. Microscopic Seroagglutination Test (SAM), with 22 Leptospira serovars, was performed in sera sample from all these animals. The aim of this study was to investigate the occurrence of antibodies against Leptospira spp. in horses from the urban area of Londrina (PR). From the samples tested, 214 (66.88%) were considered positive, with titers between 100 and 3200, being that 49 (22.90%) presented antibodies against a single serovar of Leptospira, and 165 (77.10%) samples presented antibodies against two or more serovars simultaneously, where in 88 (53.33%) it was possible to characterize the most likely probable serovar. Antibodies against the serovar Icterohaemorrhagiae were detected in 32 (23.36%) animals. Foram estudados 320 eqüinos, machos e fêmeas com idade entre dois a 17 anos, utilizados para tração de carroças na área urbana do município de Londrina (PR). Estes animais eram mantidos, após a jornada diária de serviço, em áreas ou terrenos baldios, localizados na periferia da área urbana do município. Por ocasião do atendimento, realizado entre 1996 e 2005, no Hospital Veterinário da Universidade Estadual de Londrina, nenhum dos animais apresentou sintomas sugestivos de leptospirose, sendo os motivos mais freqüentes, o emagrecimento, a indisposição para o trabalho, a verminose, problemas no sistema locomotor e feridas. A prova de soroaglutinação microscópica (SAM), com 22 sorovares de Leptospira, foi realizada em amostra de soro de todos os animais. O objetivo deste trabalho foi investigar a ocorrência de anticorpos contra Leptospira spp. em eqüinos da área urbana do município de Londrina. Foram consideradas positivas 214 (66,88%) amostras de soros com títulos entre 100 e 3200, sendo em 49 (22,90%) detectadas anticorpos contra um único sorovar de Leptospira e em 165 (77,10%) amostras com anticorpos contra dois ou mais sorovares simultâneamente, sendo em 88 (53,33%) destes caracterizado o sorovar mais provável. Anticorpos contra o sorovar Icterohaemorrhagiae foram detectados em 32 (23,36%) animais.

The genome sequences of two strains of Streptococcus pneumoniae, one of the major human pathogens, are currently available: that of the nonencapsulated laboratory strain R6, the origin of which dates back to the early 20th century, and of the serotype 4 TIGR strain isolated recently. The two genomes are not only different in size (2 versus 2.16 Mb) but differ also by approximately 10% of their genes, many of which being organized in large clusters. Their strain-specific genes and gene clusters are described here. The R6 genome contains 69 kb organized in six large regions that are absent from the TIGR strain, which in turn contains an extra 157 kb in twelve clusters compared to R6. In addition, the TIGR strain contains 13 clusters of 4 kb and larger that are not shared by a variety of genetically different S. pneumoniae strains. Many regions bear signs of gene transfer events such as the presence of insertion sequences, transposable elements, and putative site-specific integrases/recombinases. Three strain-specific regions are devoted to genes encoding proteins with the cell wall anchor motif LPXTG which are important for the interaction with host cells and appear to be highly variable, similar to cell wall-associated choline-binding proteins.