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PubMed2004

"Streptococcus milleri" endocarditis caused by Streptococcus anginosus.

Unlike other viridans streptococci, members of the "Streptococcus milleri group" are often associated with abscess formation, but are only rare causes of infective endocarditis. Although it has been shown that almost all S. intermedius isolates and most S. constellatus isolates, but only 19% of S. anginosus isolates, were associated with abscess formation, no report has addressed the relative importance of the 3 species of the "S. milleri group" in infective endocarditis. During a 5-year period (April 1997 through March 2002), 6 cases of "S. milleri" endocarditis (out of 377 cases of infective endocarditis), that fulfil the Duke's criteria for the diagnosis of infective endocarditis, were encountered. All 6 "S. milleri" isolates were identified as S. anginosus by 16S ribosomal RNA (rRNA) gene sequencing. Three patients had underlying chronic rheumatic heart disease and 1 was an IV drug abuser. Five had monomicrobial bacteremia, and 1 had polymicrobial (S. anginosus, S. mitis, Granulicatella adiacens, and Slackia exigua) bacteremia. Two patients died. None of the 6 isolates were identified by the Vitek system (GPI) or the API system (20 STREP) at >95% confidence. All 6 isolates were sensitive to penicillin G (MIC 0.008-0.064 microg/mL), cefalothin, erythromycin, clindamycin, and vancomycin. Accurate identification to the species level, by 16S rRNA gene sequencing, in cases of bacteremia caused by members of the "S. milleri group", would have direct implication on the underlying disease process, hence guiding diagnosis and treatment. Infective endocarditis should be actively looked for in cases of monomicrobial S. anginosus bacteremia, especially if the organism is recovered in multiple blood cultures.

Adult↗
PubMed2005

Dissemination of the superantigen encoding genes seeL, seeM, szeL and szeM in Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus.

Bacterial superantigens are one of the major virulence factors produced by Streptococcus pyogenes and Staphylococcus aureus. The two novel superantigen encoding genes seeM and seeL were described for S. equi subsp. equi which is known as the causative agent of strangles in equids. In the present study previously characterized S. equi subsp. equi strains and strains of various other animal pathogenic streptococcal species and subspecies were investigated for the presence of the superantigen encoding genes seeM and seeL by polymerase chain reaction. According to these studies seeL and seeM appeared to be a constant characteristic of all investigated S. equi subsp. equi strains. Surprisingly, one S. equi subsp. zooepidemicus strain (S.z. 122) was also positive for both genes. The species identity of this S. equi subsp. zooepidemicus strain could additionally be confirmed by sequencing the 16S rRNA gene and the 16S-23S rDNA intergenic spacer region. The superantigen encoding genes could not be found among additionally investigated S. equi subsp. zooepidemicus strains or among strains of seven other streptococcal species. The seeL and seeM genes of the S. equi subsp. equi strain S.e. CF32 and the genes szeL and szeM of the S. equi subsp. zooepidemicus strain S.z. 122 were cloned and sequenced. A sequence comparison revealed a high degree of sequence homology between seeL, szeL, speL and seeM, szeM and speM, respectively. The superantigenic toxins L and M seemed to be widely distributed virulence factors of S. equi subsp. equi, rare among S. equi subsp. zooepidemicus but did not occur among a number of other animal pathogenic streptococcal species.

Animals↗
PubMed1999

Streptococcus equi but not Streptococcus zooepidemicus produces potent mitogenic responses from equine peripheral blood mononuclear cells.

Streptococcus equi causes equine strangles. The acute disease has many of the hallmarks of an acute response including high fever, elevated plasma fibrinogen and neutrophilia, affects known to be mediated by proinflammatory cytokines. The objective of this study was to screen-culture supernatants from equine clinical isolates of S. equi and S. zooepidemicus for stimulation of mitogenic responses by horse peripheral blood mononuclear cells. Mitogenicity comparable to that of concanavalin A was detected in culture supernatants of S. equi strains but not in those of S. zooepidemicus. Mitogenicity was neutralised by Proteinase K and a post-strangles convalescent serum, and evidence for the presence of both thermo-resistant and thermo-labile mitogenic factors was obtained. Release of proteinaceous immunogenic mitogens in combination with the antiphagocytic protein SeM unique to S. equi may therefore contribute to some of the severe clinical manifestations of acute strangles in the horse.

Animals↗
PubMed1999

Detection of virulent strains of Streptococcus suis type 2 and highly virulent strains of Streptococcus suis type 1 in tonsillar specimens of pigs by PCR.

We developed a PCR assay for the rapid and sensitive detection of virulent Streptococcus suis type 2 and highly virulent S. suis type 1 in tonsillar specimens from pigs. The PCR primers were based on the sequence of the gene encoding the EF-protein of virulent S. suis type 2 strains (MRP+EF+) and highly virulent S. suis type 1 strains (MRP(s)EF+) and of the EF protein of weakly virulent S. suis type 2 strains (MRP+EF). The latter strains give rise to larger PCR products than the virulent strains of S. suis type 1 and 2. A positive control template was included in the assay to identify false negative results. The PCR was evaluated using tonsillar specimens from herds known (or suspected) to be infected and herds without an S. suis history. The results obtained with the PCR assay were compared with the results obtained with a newly developed bacteriological examination. In this bacteriological examination we were able to identify the EF-positive strains directly in the tonsillar specimens. From the 99 tonsils examined, 48 were positive in the PCR and 51 negative. All specimens from which EF-positive S. suis strains were isolated were also positive in the PCR assay. Three samples were positive in the PCR, but negative by bacteriological examination. The results demonstrated that the PCR is a highly specific and sensitive diagnostic tool for the detection of pigs carrying virulent strains of S. suis type 2 and highly virulent strains of type 1. Application of the assay may contribute to the control of S. suis infections.

Animals↗
PubMed1997

Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus pyogenes. The Argentinian Streptococcus Study Group.

Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.

Anti-Bacterial Agents↗
PubMed1990

Immunochemical characterization of type i carbohydrate antigen of "Streptococcus milleri" (Streptococcus anginosus).

Type-specific carbohydrate antigen of the serotype i "Streptococcus milleri" was extracted with trichloroacetic acid from purified cell walls of the type strain K39K. The extracts were then purified by chromatography on DEAE-Sephadex A-25 and Sephadex G-100 columns. The purified serotype i carbohydrate antigen produced a single precipitin band against its homologous type-specific antiserum, which fused with the band produced by the autoclaved extract of the type strain cells. The serotype i antigen was a polysaccharide composed of rhamnose, galactose and glucose in a molar ratio of 1.6:6.8:1.0. The quantitative precipitin inhibition test with various haptenic sugars showed that galactose as well as lactose produced the greatest inhibition, which suggested that a galactose in terminal beta linkage is the immunodeterminant of the serotype i-specific antigen. Galactose was detected in the autoclaved extracts from cells of all the 15 serotype i strains tested.

Antigens, Bacterial↗
PubMed1997

Distribution of capsular types and penicillin-resistance of strains of Streptococcus pneumoniae causing systemic infections in Argentinian children under 5 years of age. Streptococcus pneumoniae Working Group.

Streptococcus pneumoniae (SPN) is the most common cause of invasive infections in children, with high levels of mortality in developing countries. An increase in frequency of penicillin-resistant strains is reported in most parts of the world. A study was undertaken in Argentina and 5 other countries of the region, to determine the type distribution and penicillin resistance rate of SPN isolated from invasive infections in children less than 5 years old. Between June 1994 and March 1996, a total of 505 SPN isolated from sterile sites were collected from 15 hospitals located in 9 cities of different geographic areas. Clinical and epidemiological data from 443 children were analyzed. Sixty five percent SPN were isolated from children less than 2 years old. Pneumonia was the clinical diagnosis in 58% of the cases, meningitis in 22%, and sepsis in 10.6%. Isolates were recovered from blood (51.2%), pleural fluid (22.7%), CSF (20.7%), and other sterile sites (5.4%). Thirty different pneumococcal capsular types were identified and the 10 most frequent in descending order were: 14, 5, 1, 6A/6B, 7F, 9V, 19F, 19A, 16F y 23F, representing 89.3% of the total. Overall, 13.1% of isolates showed intermediate resistance to penicillin while 11.3% showed high resistance. Lethality was 8.8%, without correlation with penicillin-resistance and/or type. These result should be used in selecting the optimal combination of specific types for a conjugate vaccine, useful in children less than 2 years old and for considering therapeutic strategies for invasive pneumococcal infections.

Argentina↗
PubMed2005

Characterization of erythromycin-resistant Streptococcus pneumoniae in Korea, and In Vitro activity of telithromycin against erythromycin-resistant Streptococcus pneumoniae.

To characterize the phenotypes and genotypes of erythromycin-resistant clinical isolates of Streptococcus pneumoniae in Korea and to evaluate the in vitro activity of telithromycin against these erythromycin-resistant isolates, we tested a total of 676 isolates of S. pneumoniae collected from 1997 to 2002 in a tertiary hospital in Seoul, Republic of Korea. MICs for erythromycin and telithromycin were determined by the agar dilution method. The macrolide resistance phenotypes of erythromycin-resistant isolates were determined by the erythromycin- clindamycin-rokitamycin triple disk (ECRTD) and MIC induction tests, whereas their macrolide resistance genotypes were determined by PCR for the erm(B), erm(A), subclass erm(TR), and mef genes. To discriminate between mef(A) and mef(E), PCR-restriction fragment length polymorphism (RFLP) analyses were performed. Of the 676 S. pneumoniae isolates, 459 (67.9%) were resistant to erythromycin. Of the 459 erythromycin-resistant isolates, 343 (74.7%) were assigned to the cMLS phenotype, 48 (10.4%) to the iMcLS phenotype, 4 (0.9%) to the iMLS phenotype, and 64 (14.0%) to the M phenotype. The erm(B) gene was detected in 251 (54.6%) isolates, the mef gene was detected in 64 (14.0%), and both the erm(B) and mef genes were detected in 144 (31.4%) isolates. All of the mef genes detected were identified as mef(E). Of the 459 erythromycin- resistant isolates, all but one were susceptible to telithromycin. The MIC(50)/MIC(90) to telithromycin of isolates carrying erm(B), mef(E), and both genes was 0.06/0.5 microg/ml, 0.03/0.125 microg/ml, and 0.5/1.0 microg/ml, respectively. Although the MICs of telithromycin for the erythromycin-resistant isolates varied according to genotype, telithromycin was very active against these erythromycin-resistant S. pneumoniae.

Anti-Bacterial Agents↗
PubMed1995

Human endocarditis due to nutritionally variant streptococci: streptococcus adjacens and Streptococcus defectivus.

Streptococcus adjacens and S. defectivus are two recently individualized species of viridans streptococci. Both species were previously designated as nutritionally variant streptococci and characterized by their growth as small satellite colonies supported by 'helper' bacteria, or requiring complex media enriched with cysteine or with pyridoxal. Structural abnormalities were observed under these conditions and balanced growth can be obtained only with a semi-chemically defined medium, in which the cells are morphologically normal and exhibit a parietal chromophore. The two species are primarily isolated from the oral cavity, or from intestinal and genito-urinary tracts. They are likely to be responsible for most blood-culture-negative endocarditis and account for more than 4% of streptococcal strains isolated from blood cultures during this disease. Cases of endocarditis caused by these bacteria exhibit much higher rates of failure, relapse and mortality than those due to other viridans streptococci. The slow growth rate of the bacteria and the production of large amounts of exopolysaccharide in vivo may account for the difficulties encountered in treatment and suggest that a longer course of antimicrobial therapy may be required for successful cures. Results obtained from experimental models of endocarditis confirmed the efficacy of vancomycin as an alternative therapy in patients when a combination of penicillin and aminoglycoside is ineffective or contraindicated.

Animals↗
PubMed2003

Group B streptococcus (Streptococcus agalactiae) pyogenic arthritis in nonpregnant adults.

We analyzed the cases of pyogenic arthritis from group B streptococcus (GBS), or, in nonpregnant adults diagnosed in the Hospital Universitari de Bellvitge, a 1,000-bed tertiary care teaching hospital in Barcelona, Spain, during a 10-year period, and we reviewed the available literature to summarize the experience with this infectious entity. From the database of our institution, which does not attend pediatric, obstetric, or burn patients, we collected all microbiologically proven cases of infectious arthritis seen from January 1992 to December 2001. We excluded patients with infection limited to spine; patients with prosthetic joint infection; patients undergoing articular surgery during the year before diagnosis; and those with tuberculous, brucellar, or fungal arthritis. Of a total of 112 patients identified, GBS was the causative organism in 11 (10%) cases. We reviewed the literature using a MEDLINE search (1972-2001), and found 64 additional cases. Of the 75 patients, 34 (45%) were men and 41 (55%) women, with ages ranging from 20 to 87 years (mean age, 57.9 +/- 14.9 yr); 37 patients (49%) were over 60 years. Sixty-eight percent (51/75) of the patients presented with monoarthritis, while in 32% (24/75) more than 1 joint was involved. The most common location was the knee (36%), followed by the shoulder (25%). In 66% (43/65) of cases, bacteremia was documented. In 64% (47/74) of patients, a systemic predisposing factor for infection was noted; the most common conditions were diabetes mellitus, malignancies, and chronic liver diseases. In 31% (23/75) of patients, a concomitant infectious process due to the same microorganism was found, mainly vertebral osteomyelitis and urinary tract infection. Penicillin was the main antibiotic used after bacterial identification; surgical drainage was performed in 36% (27/75) of cases. The overall mortality rate was 9% (7/75). GBS is now a significant causative agent of pyogenic arthritis in nonpregnant adults. In this population, joint infection by GBS is a disease that mainly affects aged patients with underlying medical illnesses; polyarticular involvement, bacteremia, and the presence of a concomitant infectious process are frequent conditions. The case-fatality rate is substantial.

Adult↗
PubMed2004

Macrorestriction analysis of Streptococcus agalactiae (group B Streptococcus) isolates from Malaysia.

Streptococcus agalactiae or group B streptococci (GBS) often colonize the gastrointestinal and urogenital tracts of women, who may transmit these organisms to their offspring during the birth process. Using PFGE analysis, the genetic diversity of GBS was studied for strains isolated from pregnant women and their newborn infants in a teaching hospital. A total of 48 different PFGE profiles were obtained from 123 strains, with one profile (S1) appearing to be predominant among both groups studied. There was good overall correlation between the profiles obtained for strains from mother-infant pairs and for strains isolated from different body sites in the same individual. Occasional discrepancies seen in related body sites and among mother-infant pairs suggest concurrent carriage of different strains in the same individual as well as the possibility of an environmental source of organism for the neonate. The overall results demonstrated that many variants of GBS strains occur in Malaysia.

Electrophoresis, Gel, Pulsed-Field↗
PubMed1997

Identification of the common antigenic determinant shared by Streptococcus pneumoniae serotypes 35A and 20 capsular polysaccharides--structural analysis of the Streptococcus pneumoniae serotype 35A capsular polysaccharide.

The specific polysaccharide antigen of Streptococcus pneumoniae serotype 35A was shown, by a combination of one- and two-dimensional NMR methods and chemical analyses, to be a high-molecular-mass polymer composed of D-galactose, D-glucose, mannitol, and phosphate (3:1:1:1). The pentasaccharide repeating unit is polymerized through phosphate diester linkages to give the structure, [formula in text] O-Acetyl substituents are present at positions 5 and 6 of the 3)-beta-D-Galf residue and at position 2 of the 6)-beta-D-Galf residue. The capsular polysaccharides of S. pneumoniae serotypes 20 and 35A both contain the disaccharide unit -->3)-beta-D-Galf-(1-->3)-beta-D-Glcp-(1--> which is the probable structural determinant responsible for the serological cross reactivity of the two polysaccharides.

Bacterial Capsules↗
PubMed2004

Multiplex polymerase chain reaction for identification and differentiation of Streptococcus equi subsp. zooepidemicus and Streptococcus equi subsp. equi.

The closely related streptococcal species Streptococcus equi subsp. zooepidemicus and S. equi subsp. equi were identified by polymerase chain reaction using oligonucleotide primers designed according to species-specific parts of the superoxide dismutase A encoding gene sodA. A further differentiation of both subspecies could be performed by amplification of the genes seeH and seeI encoding the exotoxins SeeH and SeeI, respectively, which could be detected for S. equi subsp. equi but not for S. equi subsp. zooepidemicus. A further simplification of the identification and differentiation of both subspecies was conducted by sodA-seeI multiplex polymerase chain reaction.

Animals↗
PubMed1987

Streptococcus suis infections in Danish pigs and experimental infection with Streptococcus suis serotype 7.

During a two-year period, Streptococcus suis serotypes 1-8 were isolated from 108 pigs examined at the laboratory. S. suis serotypes 2 and 7 represented 75% of the isolates. S. suis serotype 7 was isolated more frequently than reported from other countries, and mostly from piglets less than 3 weeks of age. Experimental inoculation of 7-day-old piglets with S. suis serotype 7 provoked severe illness within a week in 6 out of 7 animals. By bacteriological and pathological examination it was found that S. suis serotype 7 was pathogenic to piglets, giving rise to septicemia with predilection for joints, serous membranes and meninges.

Animals↗
PubMed1987

Response of Streptococcus pyogenes to therapy with amoxicillin or amoxicillin-clavulanic acid in a mouse model of mixed infection caused by Staphylococcus aureus and Streptococcus pyogenes.

The response of Streptococcus pyogenes to amoxicillin or amoxicillin-clavulanic acid (Augmentin; Beecham Group) therapy of a mixed streptococcal-staphylococcal infection was studied in a surgical wound in mice. A superficial wound was produced on the backs of anesthetized mice, and a suture infected with S. pyogenes, Staphylococcus aureus, or a mixed inoculum of both organisms was inserted. Oral therapy was started 4 h after infection and continued for 3 days. Both amoxicillin and amoxicillin-clavulanic acid were effective in eliminating the streptococci from the pure wound infection. In contrast, amoxicillin failed to eliminate the streptococci from a mixed infection in which a beta-lactamase-producing strain of S. aureus was also present, wound counts reaching 10(7) streptococci per wound by 80 h, whereas amoxicillin-clavulanic acid reduced the count to less than 33 streptococci per wound by 24 h. Numbers of S. aureus were also reduced by amoxicillin-clavulanic acid therapy, controlling the infection, whereas amoxicillin was ineffective. Also of significance was the fact that successful therapy was achieved with blood and tissue concentrations of amoxicillin and clavulanic acid of the same order as those measured in humans. These results show that amoxicillin therapy failed to eliminate S. pyogenes from a wound infection in the presence of a beta-lactamase-producing strain of S. aureus and suggest the potential of amoxicillin-clavulanic acid in the treatment of mixed bacterial skin infections involving beta-lactamase-producing organisms.

Amoxicillin↗
PubMed1997

Emergence of vancomycin resistance in the genus Streptococcus: characterization of a vanB transferable determinant in Streptococcus bovis.

Streptococcus bovis NEM760 was isolated from a stool swab collected on admission from a patient as surveillance for vancomycin-resistant enterococci. Strain NEM760 was identified as S. bovis by conventional biochemical methods and partial sequence analysis of its 16S rRNA. This strain was resistant to a low level of vancomycin (MIC, 64 micrograms/ml) but was susceptible to teicoplanin (MIC, 1 micrograms/ml), and vancomycin induced resistance to both glycopeptides. The presence of a vanB-related gene in NEM760 was demonstrated in a PCR assay which enabled specific amplification of a 635-hp internal segment of vanB. Sequence analysis of the corresponding PCR product revealed that it was highly homologous (96% identity) to the prototype vanB sequence of Enterococcus faecalis V583. The VanB resistance of determinant of S. bovis NEM760 was transferred by conjugation to E. faecalis and Enterococcus faecium at a similar frequency of 2 x 10(-5) per donor. SmaI-digested genomic DNAs of independently obtained transconjugants of E. faecalis and E. faecium were analyzed by pulsed-field gel electrophoresis and Southern hybridization with a vanB DNA probe. The electrophoretic and hybridization patterns obtained with all transconjugants of the same species were indistinguishable and revealed vanB-containing chromosomal insertions of approximately 100 kb. These results suggest that the genes mediating VanB-type resistance in S. bovis NEM760 are part of large transferable genetic elements. The results presented in the report demonstrate for the first time the role of streptococci in the dissemination of vancomycin resistance among gram-positive bacteria.

Anti-Bacterial Agents↗