Haemagglutination of twitching Streptococcus sanguis

Among 86, mostly twitching, polarly fimbriated strains of Streptococcus sanguis, 55 agglutinated guinea pig erythrocytes (GPE) after cultivation in Todd-Hewitt broth (TH), and 21 strains agglutinated GPE only after growth in TH with 10% horse serum (THS). Two of the positive strains were non-twitching and unfimbriated. Ten strains failed to haemagglutinate. Among 5 twitching strains belonging to the 10043 group, 3 agglutinated GPE after growth in TH and 2 only after growth in THS. Among 35 non-twitching strains of alpha-haemolytic streptococci, only 6 agglutinated GPE after growth in TH, and among 8 negative strains which were tested after growth in THS, only 1 agglutinated GPE. Tests using 6 different kinds of erythrocytes (guinea pig, rabbit, sheep, horse, chicken, human) revealed that differences between these were slight only. The results do not indicate that there is an absolute association between twitching and haemagglutination in S. sanguis. The haemagglutination of S. sanguis was not mannose-sensitive.     

Streptococcus sanguis bacteremia and colorectal cancer

We report a patient, a 30-year-old male Japanese-Brazilian migrant construction worker, suffering from excessive daytime sleepiness for at least 6 months. Electroencephalogram recordings during his waking states showed that 10-Hz and 60-microV alpha activity was present prominently in the occipital regions. From the multiple sleep latency test, it was found that stages 1-2 NREM sleep episodes appeared repetitively without any REM episodes, and that the mean sleep latency was 10.2 min. These findings support the diagnosis that this patient suffers from subwakefulness syndrome.     

Isomalto-oligosaccharide-containing lipoteichoic acid of Streptococcus sanguis. Basic structure

The lipoteichoic acid of Streptococcus sanguis DSM 20567 and of DSM 20068 was isolated by phenol/water extraction and hydrophobic-interaction chromatography. The preparations from both strains have an identical structure: a 1,3-linked poly(glycerophosphate) chain phosphodiester-linked to Glc-(alpha 1-2)Glc(alpha 1-3)acyl2Gro as the lipid anchor. The chain is substituted with D-alanine ester and glycosyl residues which comprise mono-, di-, tri- and tetra-alpha-D-glucopyranosyl residues with (1-6) interglycosidic linkages. The glycosylglycerols were released with 48% (by mass) hydrofluoric acid, separated and characterized by a combination of chemical procedures and modern techniques of 1H-NMR and 13C-NMR spectroscopy. The alpha-isomalto-oligosaccharides add a novel motif to lipoteichoic-acid chain substituents. 1H-NMR and 13C-NMR spectroscopy also provided a detailed picture of the basic glycosylated poly(1,3-glycerophosphate) diglucosylglycerol. It proved a single unbranched chain structure, provided evidence for the chain length, the extent of glycosylation, the structure of the lipid anchor and the site of attachment of the poly(glycerophosphate) chain on the lipid anchor. Owing to its unique glycosyl substituents the lipoteichoic acid may serve as a taxonomic marker for the redefined species S. sanguis (formerly S. sanguis type I).     

Killing of Streptococcus sanguis in biofilms using a light-activated antimicrobial agent

The aim of this study was to determine whether Streptococcus sanguis, when in a biofilm, could be killed using a light-activated antimicrobial agent. Biofilms were grown on hydroxyapatite, irradiated with up to 12.2 J of light from a gallium aluminium arsenide laser in the presence of aluminium disulphonated phthalocyanine (AlPcS2) and survivors enumerated. No significant decrease in the viable count was found when either the AlPcS2 or the laser light was used alone. There was a light dose related decrease in the viable counts of irradiated AlPcS2-treated biofilms. No viable streptococci were detectable following irradiation with 12.2 J of laser light.     

Pathway for uptake and degradation of X-prolyl tripeptides in Streptococcus mutans VA-29R and Streptococcus sanguis ATCC 10556

The growth of Streptococcus mutans and Streptococcus sanguis in the oral environment requires that these micro-organisms be able to degrade salivary proteins and to assimilate the resulting peptides as an amino nitrogen source. Our research is aimed at the definition of the proteolytic enzyme systems in these oral streptococci which allow them to utilize such substrates. In the present work, the nature of the hydrolytic activity expressed by S. mutans VA-29R and S. sanguis ATCC 10556 against X-Pro4-nitroanilide and X-Pro-Y tripeptide substrates was investigated. This activity was predominantly associated with a cytoplasmic dipeptidyl peptidase which preferentially catalyzes the release of an N-terminal dipeptide from substrates in which proline is the penultimate residue. These streptococci also possess a second cytoplasmic peptidase, pepD, which catalyzes the hydrolysis of X-Pro dipeptides. We found that Gly-Pro-Ala or Ala-Pro-Gly were transported into the bacterial cells only when an energy source such as glucose was present. Peptide uptake was time-dependent, and selective exodus of peptide-derived amino acids from the bacterial cells occurred during peptide uptake. Results from these studies provide evidence that S. mutans VA-29R and S. sanguis ATCC 10556 possess a pathway for the complete degradation of X-Pro tripeptides. Transport of the peptides into cells prior to hydrolysis provides an efficient way by which all amino acids of a peptide may be obtained at an energy expense equivalent to that associated with the transport of just one amino acid. In light of the abundance of proline in salivary polypeptides, this degradative pathway could be an important component in the proteolytic pathway for salivary polypeptide utilization in these oral streptococci.     

The effect of fluoride on Streptococcus sanguis 7863 IgA1 protease production and activity

Fluoride was found to affect the production of the bacterial IgA1 protease but to have no effect on IgA1 protease activity. The concentrations of fluoride that do affect Streptococcus sanguis growth and IgA1 protease production are higher than those normally seen in vivo under normal circumstances. The concentrations of fluoride in dental plaque following use of a fluoride rinse or dentifrice would be sufficient to reduce Strep. sanguis IgA1 protease production.     

Resistance to antibiotics of Streptococcus pneumoniae strains

Streptococcus pneumoniae strains are exhibiting increasing rates of antibiotics resistance. A rapid increase of resistance was seen not only to penicillin but also other antimicrobial agents and therefore this paper describes the study of resistance and multiresistance of pneumococci to 7 antibiotics: penicillin (P), erythromycin (E), clindamycin (CC), tetracycline (T), co-trimoxazole (SXT), cefotaxime (CTX) and vancomycin (Va), using the disk-diffusion technique according to NCCLS procedure. We tested a total of 218 S. pneumoniae strains isolated from various materials: from sputum (54), noses (117), throats (28) and different swabs specimens (19). The overall percentage of resistant isolates to penicillin was 3.7%, to erythromycin--4.1%, to clindamycin--10.6%, to tetracycline--17.4%, to co-trimoxazole--15.6%, to cefotaxime--2.3%. In the sputum was most the monoresistant strains (66.7%). The multiresistance was highest in the penicillin resistant pneumococci. With the exception of vancomycin, the number of resistant strains to non-beta-lactam antibiotics (erythromycin, clindamycin, tetracycline, co-trimoxazole) was higher in penicillin-resistant strains compared with penicillin susceptible isolates. All isolates were susceptible to vancomycin.     

In vitro studies of the effect of antiseptic-containing mouthwashes on the formation and viability of Streptococcus sanguis biofilms

The aims of this study were to evaluate the growth of Streptococcus sanguis on hydroxyapatite, bovine enamel and polytetrafluoroethylene substrata in a constant depth film fermentor, and to determine the effects of three antimicrobial-containing mouthwashes on biofilm formation and bacterial viability on hydroxyapatite and enamel. There was little difference in the final cell density (5 x 10(4) cfu mm-2) of the Strep. sanguis biofilm on the three substrata. When hydroxyapatite-grown biofilms were exposed to the mouthwashes for 1 min, the one containing triclosan (T) proved the most effective. The chlorhexidine-containing mouthwash (CX) also achieved significant kills. The T-containing mouthwash was the most effective at killing biofilms grown on enamel. Pre-treatment of hydroxyapatite with CX, cetylpyridium chloride (CPC) or T for 1 min resulted in undetectable biofilm formation after 8 h. After 8 h of growth, only biofilms grown on enamel discs pre-treated with CX showed a reduction in the number of viable organisms. In conclusion, the results of this study have shown that while growth of Strep. sanguis on hydroxyapatite and enamel were similar, the ability of antimicrobial agents to prevent the accumulation of viable bacteria depended on the nature of the substratum.     

The pathogenicity factors of Streptococcus pneumoniae strains causing meningitis

Pneumococcal meningitis was registered in St. Petersburg in 1985-1991, morbidity rate being 1.7-2.3 cases per 100,000 children, including 7.4-19.8 cases among children under 1 year. Two thirds of the pneumococcal strains isolated in cases of meningitis belonged to serovars 19, 1, 6, 15 and 2. The comparative study of pneumococcal strains revealed that the presence of capsules, pneumolysin, high hyaluronidase activity or belonging to serovars 1 and 2 (irrespective of their hyaluronidase titers) were the most important factors contributing to the development of generalized infection. The role of such a factor as virulence for mice is not yet clear.     

Virulent strains of Streptococcus suis serotype 2 and highly virulent strains of Streptococcus suis serotype 1 can be recognized by a unique ribotype profile

The ribotype profiles of 42 different Streptococcus suis strains were studied. These strains belonged to five serotypes and differed in their virulence for pigs as well as in the expression of the muramidase-released protein and the extracellular protein factor. For the ribotyping, chromosomal DNAs were digested with EcoRI and were hybridized with a 1,066-bp ribosomal DNA probe. The hybridization patterns showed genetic heterogeneity within and between the serotypes. Pathogenic strains of serotype 2 and highly pathogenic strains of serotype 1 could be recognized by their unique ribotype profiles. Nonpathogenic strains showed a high degree of genetic heterogeneity. Moreover, by comparing the 16S ribosomal DNA sequences of a number of S. suis strains, we were able to design two DNA probes which specifically hybridized with S. suis strains.     

Involvement of alpha 2-adrenoreceptors and G proteins in the modulation of platelet secretion in response to Streptococcus sanguis

In the presence of plasma, human platelets secrete the contents of their dense granules and then aggregate in response to certain strains of Streptococcus sanguis. After 2 to 5 min of incubation with streptococci, platelets from fast-responding donors will begin to aggregate. Slow responders aggregate after a longer delay. Platelets may secrete after a short (fast responder) or long (slow responder) delay because of differences in the basal levels or responses to potentiating catecholamines. To test this hypothesis in vitro, endogenous basal catecholamine levels in platelets and plasma from fast and slow responders were analyzed by HPLC with electrochemical detection. The total basal concentration of epinephrine in platelets plus plasma was fourfold higher in fast responders, with the platelet compartment showing the greatest difference. The basal affinity of alpha 2-adrenoreceptors in platelets from both groups was similar when estimated using a specific antagonist, [3H]-yohimbine. Platelets from all donors showed decreased alpha 2-adrenoreceptor affinity in the presence of low (2 nM), but not higher (10 nM), concentrations of added epinephrine. Platelets in the two groups were then compared for secretion of ATP. More ATP was secreted after a shorter delay from fast responding platelets, which was mimicked in slow responders by adding physiologically attainable levels (40 nM) of epinephrine. Addition of the alpha 2-antagonist, phentolamine (10 microM), to the platelets of slow and fast responders completely inhibited or reduced secretion by one third, respectively. Therefore, alpha 2-adrenoreceptors modulate the secretory response of platelets to cells of S. sanguis.(ABSTRACT TRUNCATED AT 250 WORDS)     

IgA protease produced by Streptococcus sanguis and antibody production against IgA protease in patients with Beh?et's disease

The production of IgA protease in twelve strains of Streptococcus sanguis isolated from patients with Behcet's disease (BD) was examined. Protease activity was detected in 10 out of 12 strains. The protease was purified from one representative strain, S. sanguis 113-20, by employing Rotofor and DEAE-Sephacel chromatography. The molecular mass of the purified protease was approximately 100 kDa, and it cleaved the proline-threonine site of the IgA. Both IgG and IgA titers against the cells (113-20) and the purified IgA protease in the sera of BD patients and healthy controls, 36 each, were assayed. The IgG titers against the cells and protease were not significant in the BD patients or controls, but the IgA titers against the cells and protease in the BD patients were significantly higher than those of the controls. These data indicate that the BD patients are infected with IgA protease-producing S. sanguis strains, which cause an increase of IgA titer against these organisms and IgA protease antigen. Since the organisms can proliferate in BD patients for a long period of time (years), it seems that IgA antibodies cannot effectively eliminate the organisms.     

Construction of recombination-deficient strains of Streptococcus gordonii by disruption of the recA gene

Degenerate oligonucleotide primers were used in a polymerase chain reaction (PCR) to amplify a region of the recA sequence of Streptococcus gordonii Challis. The resulting PCR fragment was cloned into the suicide vector pAM6199 and introduced into strain Challis, giving rise to recombination-deficient strains in which the recA gene was specifically inactivated.     

Dual mechanisms of twitching during sleep in neonatal rats.

Twitches of the limbs during REM sleep in adult mammals result from descending motor activation from the brainstem. In contrast, many spontaneous movements in embryos appear similar to REM-related twitches and result from the local firing of spinal motor neurons. To determine which mechanism produces twitches in neonates, we analyzed twitching in 5- and 8-day-old rat pups that had spinal cords transected in the lower thoracic region. This transection separated motor units controlling forelimb movements from motor units controlling hindlimb movements. Spinal transection did not significantly affect the amount of forelimb twitching. In contrast, the amount of hindlimb twitching in transected pups was reduced by only 35%–50%. Given that hindlimb twitching was not eliminated by spinal transection, it is concluded that there are 2 independent mechanisms producing twitches at these ages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Right hemidiaphragmatic twitching: a complication of bipolar atrial pacing

A patient with an atrioventricular sequential pacemaker developed rhythmic contractions of the right hemidiaphragm. This was found to be the result of right phrenic nerve stimulation, which was directly related to the wide distance between the poles of an ELA atrial lead when pacing in bipolar mode. Pole separation in current atrial leads is discussed.     

Evidence of recombination and an antigenically diverse immunoglobulin A1 protease among strains of Streptococcus pneumoniae

The genetic relationships among 114 isolates of Streptococcus pneumoniae representing mainly nine serotypes that frequently cause severe childhood disease in Northern Europe were examined by use of multilocus enzyme electrophoresis. A comparison was made of the corresponding antigenic variations of excreted immunoglobulin A1 (IgA1) proteases detected by enzyme neutralization assays. Allelic variation at 13 gene loci among 70 electrophoretic types disclosed a comparatively low mean genetic diversity per locus (H = 0.319). In contrast, IgA1 proteases showed extensive antigenic diversity as 17 different inhibition types were distinguished. A lack of overall clonality was apparent from the linkage equilibrium of alleles harbored by 28 isolates chosen to represent the genetic diversity of the study population. However, certain clones, such as those marked by identical electrophoretic type, serotype, and IgA1 protease type, persisted for a sufficiently long time to enable clonal spread between distant geographic areas. Among clonally related isolates, examples illustrating a shift of capsular serotype or IgA1 protease type supported the view that recombination occurs in vivo in corresponding genes. In conclusion, over time, horizontal genetic exchange appears to be sufficiently frequent to disrupt the clonal structure otherwise generated by binary fission in natural populations of S. pneumoniae. The clonal instability combined with considerable antigenic heterogeneity renders the pneumococcal IgA1 protease less attractive as a potential component of future vaccines.     

Mechanisms of the spread of penicillin resistance in Streptococcus pneumoniae strains causing meningitis in children in France

The molecular epidemiology of penicillin-resistant Streptococcus pneumoniae strains causing meningitis in children was studied in France. Typing procedures included analysis of total DNA polymorphism by random amplification of polymorphic DNA, restriction fragment length polymorphism (RFLP) analysis of the ribosomal RNA gene regions, and pulsed-field gel electrophoresis. Penicillin-binding protein (PBP) genes pbp2b and pbp2x were studied by RFLP analysis and DNA sequencing in selected cases. Statistical analysis of the data by factorial analysis of correspondence established that the emergence of penicillin-resistant pneumococci in this pathology is the result of the spread of two highly resistant closely related clusters and a cluster of serotype 23 strains with an intermediate level of resistance, the spread of genes confering high resistance to penicillin between the two highly resistant clusters, and complex genetic events involving the pbp genes in a heterogeneous population of strains leading to an intermediate level of resistance.     

Comparison of E test with standard broth microdilution for determining antibiotic susceptibilities of penicillin-resistant strains of Streptococcus pneumoniae

We compared the E test (AB Biodisk North America, Inc., Culver City, Calif.) with the National Committee for Clinical Laboratory Standards broth microdilution method for the determination of MICs of penicillin and cefotaxime for 108 isolates of Streptococcus pneumoniae. The E test was performed following manufacturer's recommendations with Mueller-Hinton blood agar, and the broth microdilution procedure was performed with lysed horse blood-supplemented Mueller-Hinton broth. The microdilution method classified 26 isolates as highly penicillin resistant (MIC, > or = 2 micrograms/ml), 33 as intermediately resistant to penicillin (MIC, > or = 0.1 < 2.0 micrograms/ml), and 49 as susceptible to penicillin (MIC, < 0.1 micrograms/ml). Discordant results obtained with the E test for penicillin susceptibility testing compared with broth microdilution occurred for 19 of the 108 isolates tested. Cefotaxime MICs for 90% of isolates found highly resistant, intermediately resistant, and susceptible to penicillin by broth microdilution were 2.0, 0.5, and 0.06 micrograms/ml, respectively. There were 16 susceptibility category changes when the E test was used to determine cefotaxime MICs. All of the discrepancies in the penicillin and cefotaxime MICs determined by the E test occurred at the susceptibility category breakpoints, and all represented differences of only one twofold dilution factor. Properly performed and controlled, the E test should be a reliable quantitative procedure for more accurately predicting the susceptibility of S. pneumoniae to several antibiotics.     

Antimicrobial resistance and serotype distribution of Streptococcus pneumoniae strains causing childhood infections in Bangladesh, 1993 to 1997

Three hundred sixty-two Streptococcus pneumoniae strains were isolated from children under 5 years of age at Dhaka Shishu (Children) Hospital from 1993 to 1997. The strains were isolated from blood (n = 105), CSF (n = 164), ear swab (n = 61), eye swab (n = 20), and pus (n = 12). Of the 362 isolates, 42 (11.6%) showed intermediate resistance (MIC, <0.1 microgram/ml) and only 4 (1.1%) showed complete resistance (MIC, >2.0 microgram/ml) to penicillin. Penicillin resistance exhibited a strong relationship with serotype 14; 47.8% of the penicillin-resistant strains belonged to this type. A remarkably high (64.1%) resistance to co-trimoxazole was observed, along with a significant increase during the time period studied; there was no relationship to capsular type. By way of contrast, penicillin resistance did not show any significant change during the study period. Resistance to chloramphenicol (2.2%) and erythromycin (1.1%) was rare. The high resistance to co-trimoxazole and its increasing trend demand elucidation of the clinical impact of pneumonia treatment by this antimicrobial and reconsideration of the World Health Organization recommendation for co-trimoxazole administration to children with community-acquired pneumonia at the health care worker level in Bangladesh.     

Hypervariability generated by natural selection in an extracellular complement-inhibiting protein of serotype M1 strains of group A Streptococcus

In many countries, M1 strains of the human pathogenic bacterium group A Streptococcus are the most common serotype recovered from patients with invasive disease episodes. Strains of this serotype express an extracellular protein that inhibits complement [streptococcal inhibitor of complement (Sic)] and is therefore believed to be a virulence factor. Comparative sequence analysis of the 915-bp sic gene in 165 M1 organisms recovered from diverse localities and infection types identified 62 alleles. Inasmuch as multilocus enzyme electrophoresis and pulsed-field gel electrophoresis previously showed that most M1 organisms represent a distinct streptococcal clone, the extent of sic gene polymorphism was unexpected. The level of polymorphism greatly exceeds that recorded for all other genes examined in serotype M1 strains. All insertions and deletions are in frame, and virtually all nucleotide substitutions alter the amino acid sequence of the Sic protein. These molecular features indicate that structural change in Sic is mediated by natural selection. Study of 70 strains recovered from two temporally distinct epidemics of streptococcal infections in the former East Germany found little sharing of Sic variants among strains recovered in the different time periods. Taken together, the data indicate that sic is a uniquely variable gene and provide insight into a potential molecular mechanism contributing to fluctuations in streptococcal disease frequency and severity.