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PubMed2005

[Severe Streptococcus agalactiae infection of the diabetic foot. A deleterious role of Streptococcus agalactiae?].

INTRODUCTION: Screening strategies among pregnant women have decreased the incidence of group B Streptococcus, which causes severe neonatal infections. The incidence of these infections has increased among diabetic patients, however. OBJECTIVES: To specify the characteristics of diabetic foot infections in which surgical samples have isolated one or several germs including group B Streptococcus, study its risk factors and determine its course. MATERIALS AND METHODS: We retrospectively evaluated the records of all patients admitted to the University Hospital of Geneva from January 1999 through October 2004, with diagnoses of severe foot infection (+/- osteomyelitis) documented during surgery. RESULTS: Twenty-five severe diabetic foot infections were identified, 21 with osteomyelitis. The most common risk factors were age older than 60 years (n=10), chronic renal failure (n=7), severe arteriopathy (n=6), and immune depression (n=2). Most lesions were classified as grade 3 or 4 of Wagner's classification. 80% of the surgical samples were polymicrobial. Blood cultures were positive in 4 patients, one in septic shock. Half the patients (n=13) underwent amputation, despite initially appropriate antibiotic treatment. No patients died but 3 relapsed. CONCLUSION: Group B streptococcal foot infections often occur in fragile patients with immune depression or severe arterial disease. Despite intensive antibiotic therapy and adequate debridement, amputation is often required in diabetic patients because of severe damage to the tissue and poor vascularization.

Adult↗
PubMedDate not supplied

[Streptococcus agalactiae infective endocarditis].

Streptococcus agalactiae infective endocarditis Streptococcus agalactiae is an unusual cause of infectious endocarditis. We describe the clinical characteristics, therapy and evolution of this infection in four patients diagnosed between 1996 and 2003. All four cases had native valve involvement and vegetations. All the patients had severe aortic failure and three of them also developed heart failure. Valve replacement surgery was performed in all four cases. Mortality was 50%. Infectious endocarditis due to S. agalactiae is very aggressive. Early surgery should be considered to prevent valve destruction and serious complications.

Adult↗
PubMed2006

Transport of multidrug resistance substrates by the Streptococcus agalactiae hemolysin transporter.

Streptococcus agalactiae (group B streptococcus [GBS]) causes neonatal sepsis, pneumonia, and meningitis, as well as infections of the bovine udder. The S. agalactiae hemolysin is regarded as an important virulence factor, and hemolysin expression is dependent on the cyl gene cluster. cylA and cylB encode the ATP binding and transmembrane domains of a typical ATP binding cassette (ABC) transporter. The deduced proteins contain the signature sequence of a multidrug resistance (MDR) transporter, and mutation of the genes results in a nonhemolytic and nonpigmented phenotype. To further elucidate the function of the putative transporter, nonpolar deletion mutants of cylA were constructed. These mutants are nonhemolytic and can be complemented by the transporter genes. Wild-type strain and nonhemolytic cylA and cylK deletion mutants were exposed to known substrates of MDR transporters. Mutation of cylA significantly impaired growth in the presence of daunorubicin, doxorubicin, and rhodamine 6G and resulted in a decreased export of doxorubicin from the cells. The mutation of cylK, a gene of unknown function located downstream from cylA, caused a loss of hemolysis but had no effect on the transport of MDR substrates. Furthermore, the hemolytic activity of the wild-type strain was inhibited by reserpine in a dose-dependent manner. We conclude that CylAB closely resembles an ABC-type MDR transporter and propose that the GBS hemolysin molecule represents a natural substrate of the transporter.

Anti-Bacterial Agents↗
PubMed2003

Subtractive hybridization identifies a novel predicted protein mediating epithelial cell invasion by virulent serotype III group B Streptococcus agalactiae.

Group B Streptococcus agalactiae bacteria (group B streptococci [GBS]) are the most common cause of serious bacterial infection in newborn infants. The majority of serotype III-related cases of neonatal disease are caused by a genetically related subgroup of bacteria, restriction fragment digest pattern (RDP) type III-3, suggesting that these strains possess unique genes contributing to virulence. We used genomic subtractive hybridization to identify regions of genomic DNA unique to virulent RDP type III-3 GBS strains. Within one of these III-3-specific regions is a 1,506-bp open reading frame, spb1 (surface protein of group B streptococcus 1). A mutant type III GBS strain lacking Spb1 was constructed in virulent RDP type III-3 strain 874391, and the interactions of the wild-type and spb1 isogenic mutant with a variety of epithelial cells important to GBS colonization and infection were compared. While adherence of the spb1 isogenic mutant to A549 respiratory, C2Bbe1 colonic, and HeLa cervical epithelial cells was slightly lower than that of the 874391 strain, invasion of the Spb1(-) mutant was significantly reduced with these cell lines compared to what was seen with 874391. The defect in epithelial invasion was corrected by supplying spb1 in trans. These observations suggest that Spb1 contributes to the pathogenesis of neonatal GBS infection by mediating internalization of virulent serotype III GBS and confirm that understanding of the population structure of bacteria may lead to insights into the pathogenesis of human infections.

Amino Acid Sequence↗
PubMed1979

Surface protein of a Streptococcus agalactiae isolate.

A Streptococcus agalactiae isolate of bovine origin was cultured in broth; log-phase cells were washed and radioiodinated and subsequently extracted at low pH in the presence of a nonionic detergent. A protein antigen was purified from concentrated extract by ultracentrifugation, gel filtration, and ion-exchange chromatography. The molecular weight of the protein was estimated at 31,800. The agglutinogenic character of the protein indicated its localization at the cell surface.

Antigens, Bacterial↗
PubMed2006

Use of a serotype-specific DNA microarray for identification of group B Streptococcus (Streptococcus agalactiae).

Group B Streptococcus (GBS; Streptococcus agalactiae) is an important cause of sepsis and meningitis. Nine GBS serotypes, based on capsular polysaccharide (CPS) antigens, have been described. Their distribution varies worldwide and needs to be monitored to understand the epidemiology of GBS disease and inform the development of vaccines. In this study, we sequenced cpsH of GBS serotype II (cpsHII) and compared it with that of the other eight serotypes to identify serotype-specific regions. We then developed a DNA microarray based on the cpsH gene and used it to test 88 GBS isolates-9 serotype reference strains and 79 clinical isolates-and 7 other bacterial and fungal species which are commonly present in the vagina flora. The microarray was shown to be specific and reproducible. This is the first report of a microarray which can identify the nine GBS serotypes. The use of a microarray has advantages over traditional serotyping methods and will be of practical value in both reference and diagnostic laboratories.

Bacterial Capsules↗
PubMed2001

Hyaluronan binding and degradation by Streptococcus agalactiae hyaluronate lyase.

Streptococcus agalactiae hyaluronate lyase is a virulence factor that helps this pathogen to break through the biophysical barrier of the host tissues by the enzymatic degradation of hyaluronan and certain chondroitin sulfates at beta-1,4 glycosidic linkages. Crystal structures of the native enzyme and the enzyme-product complex were determined at 2.1- and 2.2-A resolutions, respectively. An elongated cleft transversing the middle of the molecule has been identified as the substrate-binding place. Two product molecules of hyaluronan degradation were observed bound to the cleft. The enzyme catalytic site was identified to comprise three residues: His(479), Tyr(488), and Asn(429). The highly positively charged cleft facilitates the binding of the negatively charged polymeric substrate chain. The matching between the aromatic patch of the enzyme and the hydrophobic patch of the substrate chain anchors the substrate chain into degradation position. A pair of proton exchanges between the enzyme and the substrate results in the cleavage of the beta-1,4 glycosidic linkage of the substrate chain and the unsaturation of the product. Phe(423) likely determines the size of the product at the product release side of the catalytic region. Hyaluronan chain is processively degraded from the reducing end toward the nonreducing end. The unsulfated or 6-sulfated regions of chondroitin sulfate can also be degraded in the same manner as hyaluronan.

Amino Acid Sequence↗
PubMed1997

Streptococcus agalactiae mastitis: a review.

Streptococcus agalactiae continues to be a major cause of subclinical mastitis in dairy cattle and a source of economic loss for the industry. Veterinarians are often asked to provide information on herd level control and eradication of S. agalactiae mastitis. This review collects and collates relevant publications on the subject. The literature search was conducted in 1993 on the Agricola database. Articles related to S. agalactiae epidemiology, pathogen identification techniques, milk quality consequences, and control, prevention, and therapy were included. Streptococcus agalactiae is an oblique parasite of the bovine mammary gland and is susceptible to treatment with a variety of antibiotics. Despite this fact, where state or provincial census data are available, herd prevalence levels range from 11% (Alberta, 1991) to 47% (Vermont, 1985). Infection with S. agalactiae is associated with elevated somatic cell count and total bacteria count and a decrease in the quantity and quality of milk products produced. Bulk tank milk culture has, using traditional milk culture techniques, had a low sensitivity for identifying S. agalactiae at the herd level. New culture methods, using selective media and large inocula, have substantially improved the sensitivity of bulk tank culture. Efficacy of therapy on individual cows remains high. Protocols for therapy of all infected animals in a herd are generally successful in eradicating the pathogen from the herd, especially if they are followed up with good udder hygiene techniques.

Animals↗
PubMed2002

Complete genome sequence and comparative genomic analysis of an emerging human pathogen, serotype V Streptococcus agalactiae.

The 2,160,267 bp genome sequence of Streptococcus agalactiae, the leading cause of bacterial sepsis, pneumonia, and meningitis in neonates in the U.S. and Europe, is predicted to encode 2,175 genes. Genome comparisons among S. agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes, and the other completely sequenced genomes identified genes specific to the streptococci and to S. agalactiae. These in silico analyses, combined with comparative genome hybridization experiments between the sequenced serotype V strain 2603 V/R and 19 S. agalactiae strains from several serotypes using whole-genome microarrays, revealed the genetic heterogeneity among S. agalactiae strains, even of the same serotype, and provided insights into the evolution of virulence mechanisms.

Amino Acid Sequence↗
PubMed1999

Low prevalence of the immunoglobulin-A-binding beta antigen of the C protein among Streptococcus agalactiae isolates causing neonatal sepsis.

Streptococcus agalactiae (Group B streptococcus, GBS) is the most important pathogen causing neonatal sepsis. The role of bacterial proteins contributing to pathogenicity in GBS infections has not yet been clearly determined, but the C protein complex has been suggested to be involved in both virulence and protective immunity. The aim of this study was to assess the prevalence of GBS strains bearing the gene encoding for the beta antigen of the C protein among clinical isolates from 68 neonates with sepsis, 45 newborns colonized without clinical signs of infection, and 50 isolates from pregnant women. The prevalence of the beta antigen gene in all three groups was low (24% vs. 19% vs. 22%) [corrected], and the differences between groups were not statistically significant. Clinical characteristics and cytokine plasma levels did not differ between septic patients with beta antigen-positive and -negative strains. The beta-antigen gene was not found among serotype III isolates, which accounted for roughly half of all the strains isolated. Thus, polymerase chain reaction (PCR) analysis based on the beta antigen gene seems not helpful for distinguishing invasive from colonizing GBS strains. A vaccine based on peptide antigens from the beta antigen of the C protein would most probably not provide protection against the majority of GBS isolates. When analyzing the PCR products of the C protein beta antigen gene by DNA sequencing, a genetic heterogeneity was observed, revealing small repetitive genetic elements within the amplified fragment, an observation that should be studied further.

Antigens, Bacterial↗
PubMed1984

Cystine antagonism of the antibacterial action of lactoperoxidase-thiocyanate-hydrogen peroxide on Streptococcus agalactiae.

Cystine reduction in Streptococcus agalactiae, resulting in sulfhydryl formation, may account for antagonism of the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide when cystine is present in excess of the amount needed for maximum growth. Accumulation of cystine by S. agalactiae and its reduction to form sulfhydryl compounds were demonstrated. The reduction of cystine appeared to occur by a couple reaction between glutathione reductase and glutathione-disulfide transhydrogenase activity, both of which were found in the supernatant fraction from cell homogenates. NADPH-specific glutathione reductase activity was found in the pellet and supernatant fractions from cell homogenates. Two sulfhydryls were formed for each mole of NADPH used during cystine reduction. The information presented offers a plausible explanation of how cystine, when present in excess of growth needs, may be reduced to generate sulfhydryl compounds which neutralize the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide on S. agalactiae.

Cystine↗
PubMed1997

Cloning and characterization of a novel macrolide efflux gene, mreA, from Streptococcus agalactiae.

A strain of Streptococcus agalactiae displayed resistance to 14-, 15-, and 16-membered macrolides. In PCR assays, total genomic DNA from this strain contained neither erm nor mef genes. EcoRI-digested genomic DNA from this strain was cloned into lambda Zap II to construct a library of S. agalactiae genomic DNA. A clone, pAES63, expressing resistance to erythromycin, azithromycin, and spiramycin in Escherichia coli was recovered. Deletion derivatives of pAES63 which defined a functional region on this clone that encoded resistance to 14- and 15-membered, but not 16-membered, macrolides were produced. Studies that determined the levels of incorporation of radiolabelled erythromycin into E. coli were consistent with the presence of a macrolide efflux determinant. This putative efflux determinant was distinct from the recently described Mef pump in Streptococcus pyogenes and Streptococcus pneumoniae and from the multicomponent MsrA pump in Staphylococcus aureus and coagulase-negative staphylococci. Its gene has been designated mreA (for macrolide resistance efflux).

Amino Acid Sequence↗
PubMed2005

Epidemiology of Streptococcus agalactiae colonization in Germany.

Streptococcus agalactiae can cause severe pneumonia, sepsis and meningitis in neonates and remains one of the most prevalent causes of invasive neonatal infections. Maternal transmission of S. agalactiae during delivery can be prevented by prenatal screening and peripartal antibiotic prophylaxis. Implementation of CDC guidelines for group B streptococci (GBS) disease prevention resulted in a significant decline of invasive neonatal S. agalactiae infections in the USA. Similar national guidelines were issued in 2000 for Germany. However, the epidemiology of S. agalactiae colonization in Germany has not been investigated for more than 15 years and the impact these guidelines will have is therefore unknown. To assess colonization rates in Germany, we cultured vaginal and rectal swabs for S. agalactiae from pregnant and non-pregnant adult patients in the region of Aachen and Munich. Swabs were cultivated in selective broth medium for 24h and subsequently plated on blood agar plates according to the CDC recommendations. Colonies negative for catalase and pyrrolidonyl aminopeptidase were further differentiated by the CAMP test and a DNA probe specific for S. agalactiae. Rectal or vaginal colonization of S. agalactiae was found in 34 (16%) of 210 pregnant patients and in 41 (16%) of 250 non-pregnant women. S. agalactiae was found only in rectal swabs in 4% of pregnant and non-pregnant patients. For further characterization of the strains capsular serotypes and major surface protein antigens were determined by Ouchterlony immunodiffusion and PCR. Among the 75 different patient isolates serotype III was the most prevalent with 21 (28%) isolates, followed by 16 (21%) isolates of serotype II, 13 (17%) isolates of serotype Ia, 12 (16%) of serotype V, 11 (15%) of serotype Ib and only 2 (3%) isolates of serotype IV. The vast majority of all strains harbored genes for the major surface protein antigens, the alpha-C-protein or alpha-C-protein like antigens like Alp2-4, epsilon and Rib. These data show that S. agalactiae colonization is common in Germany and strict adherence to the guidelines for the preventions of GBS disease will result in peripartal antibiotic prophylaxis in up to 20% of all deliveries.

Bacterial Capsules↗
PubMed1999

Lmb, a protein with similarities to the LraI adhesin family, mediates attachment of Streptococcus agalactiae to human laminin.

Streptococcus agalactiae is a leading cause of neonatal sepsis and meningitis. Adherence to extracellular matrix proteins is considered an important factor in the pathogenesis of infection, but the genetic determinants of this process remain largely unknown. We identified and sequenced a gene which codes for a putative lipoprotein that exhibits significant homology to the streptococcal LraI protein family. Mutants of this locus were demonstrated to have substantially reduced adherence to immobilized human laminin. The nucleotide sequence of the gene was subsequently designated lmb (laminin binding) and shown to be present in all of the common serotypes of S. agalactiae. To determine the role of Lmb in the adhesion of S. agalactiae wild-type strains to laminin, a recombinant Lmb protein harboring six consecutive histidine residues at the C terminus was cloned, expressed, and purified from Escherichia coli. Preincubation of immobilized laminin with recombinant Lmb significantly reduced adherence of the wild-type strain O90R to laminin. These results indicate that Lmb mediates the attachment of S. agalactiae to human laminin, which may be essential for the bacterial colonization of damaged epithelium and translocation of bacteria into the bloodstream.

Adhesins, Bacterial↗
PubMed1999

Identification of genetic determinants for the hemolytic activity of Streptococcus agalactiae by ISS1 transposition.

Streptococcus agalactiae is a poorly transformable bacterium and studies of molecular mechanisms are difficult due to the limitations of genetic tools. Employing the novel pGh9:ISS1 transposition vector we generated plasmid-based mutant libraries of S. agalactiae strains O90R and AC475 by random chromosomal integration. A screen for mutants with a nonhemolytic phenotype on sheep blood agar led to the identification of a genetic locus harboring several genes that are essential for the hemolytic function and pigment production of S. agalactiae. Nucleotide sequence analysis of nonhemolytic mutants revealed that four mutants had distinct insertion sites in a single genetic locus of 7 kb that was subsequently designated cyl. Eight different open reading frames were identified: cylX, cylD, cylG, acpC, cylZ, cylA, cylB, and cylE, coding for predicted proteins with molecular masses of 11, 33, 26, 11, 15, 35, 32, and 78 kDa, respectively. The deduced amino acid sequence of the protein encoded by cylA harbors a conserved ATP-binding cassette (ABC) motif, and the predicted proteins encoded by cylA and cylB have significant similarities to the nucleotide binding and transmembrane proteins of typical ABC transporter systems. Transcription analysis by reverse transcription-PCR suggests that cylX to cylE are part of an operon. The requirement of acpC and cylZABE for hemolysin production of S. agalactiae was confirmed either by targeted mutagenesis with the vector pGh5, complementation studies with pAT28, or analysis of insertion elements in naturally occurring nonhemolytic mutants.

Animals↗
PubMed1999

Properties and distribution of the putative R3 protein of Streptococcus agalactiae.

Strain-variable Streptococcus agalactiae (group B streptococci; GBS) proteins exposed at the bacterial cell surface are important markers in GBS serotyping. These proteins include the c proteins c(alpha) and c(beta) and the R proteins R1 through R4, of which R1 and R4 have been studied most extensively. This study presents the characteristics of a protein which was expressed by a capsular antigen type V GBS strain shown by means of polyclonal and monoclonal antibody testing. Examination of a number of reference and prototype strains by fluorescent antibody testing and Western blotting provided evidence that the serotype V-derived protein was the R3 protein of GBS, previously defined on the basis of immunoprecipitation assays. The putative R3 protein formed ladder-like banding patterns on Western blotting with polypeptides in the 30 kDa to > or = 140 kDa range, was destroyed by pepsin digestion, and partially degraded by trypsin digestion. The protein was expressed by 10 (6.5%) of 153 clinical GBS strains tested, the expression being restricted to isolates of the capsular antigen types II, III, and V. Some isolates expressed both the c(beta) and the R3 protein. Expression in combination with c(alpha) or R4 protein synthesis was not detected. Inclusion of the anti-R3 monoclonal antibody among antibody reagents for GBS serotyping will enhance the discriminatory power of this typing method.

Animals↗
PubMed2006

[Antimicrobial susceptibilities and serotype distribution of Streptococcus agalactiae strains isolated from pregnant women].

Streptococcus agalactiae (Group B streptococcus, GBS) is an important cause of neonatal morbidity and mortality. The aim of this study was to determine the serotype distribution and antibiotic susceptibility patterns of GBS isolated from pregnant women. A total of 671 pregnant women were screened for vaginal carriage of GBS, and vaginal colonization rate was found to be 14.6%. All GBS isolates were susceptible to penicillin, vancomycin, chloramphenicol and ofloxacin. The rates of GBS resistance to tetracycline, erythromycin and clindamycin were 81.6%, 24.5% and 19.4%, respectively. The serotype distribution of GBS isolates was as follows in order of frequency; serotype III (33.7%), serotype Ib (24.5%), serotype V (18.4%), serotype Ia (7.1%), serotype IV (3.1%) and serotype II (2%). Eleven GBS isolates could not be serotyped by the antisera set used in the study.

Anti-Infective Agents↗