Aims: Maternal vaginal Group B Streptococcus (GBS) colonization is considered a risk factor for preterm delivery and, consequently, neonatal infections. Previous studies have portrayed the important roles of these virulence factors, including hemolytic pigment, hyaluronidase (HylB), serine-rich protein (Srr) and bacterial surface adhesion of GBS (BsaB) in mediating GBS colonization and intrauterine ascending infection, causing preterm delivery. This study aimed to investigate the association between mRNA expression of virulence genes in GBS isolates obtained from symptomatic pregnant women and preterm delivery. Methodology and results: GBS isolates were obtained from high vaginal swabs of 40 symptomatic pregnant women of gestational age of less than 37 weeks. RNA was extracted from these GBS isolates and RT-qPCR was performed to determine the relative mRNA expression of GBS virulence genes, including CylE (encode enzyme required for the biosynthesis of the hemolytic pigment), HylB, Srr-1 and BsaB. Socio-demographic details and obstetric history were not found to be associated with the delivery outcomes of these women. The GBS isolates from symptomatic pregnant women who delivered prematurely showed a higher expression of CylE gene and a trend towards an elevated expression of HylB gene compared to women with term delivery. Meanwhile the expression of both Srr-1 and BsaB genes was similar between symptomatic pregnant women who had term or preterm delivery. Conclusion, significance and impact of study The results suggest that following vaginal colonization, both CylE and HylB genes are likely to contribute to intrauterine ascending infection and inflammation, leading to preterm delivery in humans. These virulence factors may be targeted for the pre-clinical stages of vaccine development or therapeutic intervention.
Streptococcus agalactiae--isolation & ; purification ; Pregnant Women

OBJECTIVETo establish a simple and rapid method to detect Streptococcus mutans and streptococcus sobrinus simultaneously in human saliva.

METHODSChromosomal DNA from the bacteria was obtained by the extraction method with phenol-chloroform. A nested PCR method with two sets of primers specific for portions of the glucosyltransferase genes (gtfB of S. mutans and gtfI of S. sobrinus), was optimized to detect S. mutans and S. sobrinus from standard strains, clinical strains and directly in human saliva.

RESULTSThe first process of nested PCR was capable of amplifying DNA fragments specific for these species from chromosomal DNA extracted from 10(5) CFU cells of standard and clinical strains, or from 1 ml clinical saliva samples containing 10(5) CFU cells of either species. a second process of nested PCR, using the first PCR product as a template with new internal primers to detect 10(3) CFU of either streptococcal species in 1ml saliva samples.

CONCLUSIONNested PCR could detect S. mutans and S. sobrinus rapidly and simply in human saliva. This finding would be important to studies of elucidation the role of these two streptococcal species in the etiology of dental caries.

Humans ; Polymerase Chain Reaction ; Saliva ; microbiology ; Streptococcus mutans ; genetics ; isolation & purification ; Streptococcus sobrinus ; genetics ; isolation & purification

OBJECTIVETo observe the dynamic changes of oral microflora early colonized in infants.

METHODSThe oral swab samples for the study were taken in 1 day, 1, 3, 6, 9, 12 months after birth from 12 healthy neonates. By choosing suitable diluted concentration, the samples were incubated aerobically, facultative anaerobically and anaerobically. The strains were identified by observing colony characteristics, Gram staining and biochemical tests.

RESULTSS. salivarius was the most frequent microflora, followed by S. mitis, S. sanguis, S. gordonii and S. mutans occurred in oral cavity after tooth eruption. Veillonella spp. can be detected in oral cavity of 1-month-old babies, A. odontolyticus was isolated from 8.3% infants of more than 3 months old. L. acidophilus maintained the lower prevalence in oral cavity of babies. Leptotrichia buccalis and Capnocytophaga spp. occurred in oral cavity of some dentate infants.

CONCLUSIONS. solivarius and S. mitis are predominant species in oral cavity of the infants, Veillonella spp. is the first and the most anaerobic species appeared in oral cavity of healthy babies. A. odontolyticus is the first actinomyces detected in oral cavity. With the increasing months, kind and amount of microflora increase dramatically.

Actinomyces ; isolation & purification ; Colony Count, Microbial ; Female ; Humans ; Infant ; Infant, Newborn ; Longitudinal Studies ; Male ; Mouth ; microbiology ; Mouth Mucosa ; microbiology ; Saliva ; microbiology ; Streptococcus ; classification ; isolation & purification ; Streptococcus mitis ; isolation & purification ; Streptococcus mutans ; isolation & purification ; Streptococcus sanguis ; isolation & purification ; Veillonella ; isolation & purification

The optimal site for the isolation of beta-hemolytic streptococci (BHS) from throat cultures was investigated in 164 healthy elementary school children. All throat cultures were streaked onto duplicate blood agar plates (BAP), one of which was taken from the tonsillar fossae and the other from the posterior pharynx. BHS were isolated in cultures from 56 (34.2%) of the children. BHS were more frequently recovered from the tonsillar fossae than from the posterior pharynx (54 vs. 47; both sites, 45; tonsillar fossae only, 9; posterior pharynx only, 2; P<0.0001). There were significantly more numerous colonies in the tonsillar fossae than in the posterior pharynx (p<0.01). To conclude, the tonsillar fossae are more optimal sites of throat cultures to isolate BHS than the posterior pharynx.
Bacteriological Techniques ; Child ; Humans ; Pharynx/*microbiology ; Streptococcus/*isolation & purification

China ; epidemiology ; Humans ; Streptococcal Infections ; epidemiology ; Streptococcus suis ; isolation & purification

To determine the carrier rate of beta-hemolytic streptococci (BHS), throat cultures were taken from healthy elementary school children in four separate areas of Korea from 1992 to 1995, including Inje, Nonsan, Seoul and Chinju. The strains of Streptococcus pyogenes had been serotyped with anti-T, -OF and -M sera. The isolation rates of BHS and S. pyogenes ranged from 14.1-32.4% and 10.9-18.5% respectively. More than half of the carriers showed heavy growth of BHS. M78 (48.6%) and M28 (22.2%) were most common in Inje, M12 (23.6%) and M5 (20.3%) in Nonsan, M12 (48.8%) and M5 (14.6%) in Seoul, and M12 (26.3%) and M22 (14.5%) in Chinju, respectively. About 15% of school children were positive for S. pyogenes in throat cultures, and the distribution of serotypes varied according to geographical regions.
Carrier State ; Child ; Child, Preschool ; Female ; Human ; Male ; Pharynx/microbiology* ; Schools ; Serotyping* ; Streptococcus pyogenes/isolation & purification* ; Streptococcus pyogenes/classification*

PURPOSE: Erythromycin-resistant beta-hemolytic streptococci (BHS) has recently emerged and quickly spread between and within countries throughout the world. In this study, we evaluate the antimicrobial susceptibility patterns and erythromycin resistance mechanisms of BHS during 2003-2004. MATERIALS AND METHODS: The MICs of seven antimicrobials were determined for 204 clinical isolates of BHS from 2003 to 2004. Resistance mechanisms of erythromycin-resistant BHS were studied by the double disk test as well as by polymerase chain reaction (PCR). RESULTS: Compared with our previous study, resistance among Streptococcus pyogenes isolates to a variety of drugs decreased strikingly: from 25.7% to 4.8% in erythromycin; 15.8% to 0% in clindamycin; and 47.1% to 19.0% in tetracycline. The prevalent phenotypes and genotypes of macrolide-lincosamide-streptograminB (MLSB) resistance in Streptococcus pyogenes isolates have been changed from the constitutive MLSB phenotype carrying erm(B) to the M phenotype with mef(A) gene. In contrast with Streptococcus pyogenes, resistance rates to erythromycin (36.7%), clindamycin (43.1%), and tetracycline (95.4%) in Streptococcus agalactiae isolates did not show decreasing trends. Among the Streptococcus dysgalactiae subsp. equisimilis isolates (Lancefield group C, G), resistance rates to erythromycin, clindamycin, tetracycline and chloramphenicol were observed to be 9.4%, 3.1%, 68.8%, and 9.4%, respectively. CONCLUSION: Continual monitoring of antimicrobial resistance among large-colony-forming BHS is needed to provide the medical community with current data regarding the resistance mechanisms that are most common to their local or regional environments.
Anti-Bacterial Agents/*pharmacology ; Drug Resistance, Multiple, Bacterial ; Erythromycin/*pharmacology ; Genes, Bacterial ; Genotype ; Hospitals ; Humans ; Incidence ; Korea ; Microbial Sensitivity Tests ; Streptococcus/*drug effects/genetics/isolation & purification ; Streptococcus agalactiae/drug effects/genetics/isolation & purification ; Streptococcus pyogenes/drug effects/genetics/isolation & purification

OBJECTIVETo investigate the relationship between genotypic diversity of Streptococcus mutans (Sm) and deciduous teeth caries in Xinjiang Uygur autonomous region.

METHODSIsolates of Sm were obtained from 17 caries-free and 17 caries-active Uygur preschool children aged from 3 to 5 years. A total of 143 isolates were subcultured, biochemically characterised and identified by polymerase chain reaction (PCR) as Sm and Streptococcus sobrinus (Ss). Then the Sm isolates were genotyped by arbitrarily primed-PCR (AP-PCR).

RESULTSA total of 81 Sm isolates from caries-active subjects and 62 isolates from caries-free subjects were identified by PCR and forty distinct genotypes identified from 143 clinical isolates. In seventeen caries-active group, 9 children had only 1 genotype, 5 children had 2 genotypes, 3 children had 3 genotypes. In seventeen caries-free group, 14 children had only 1 genotype, 3 children had more than 2 genotypes. The Spearman correlation test showed a strong association between genotypic diversity and caries experience (r = 0.342, P < 0.05).

CONCLUSIONSIsolates of Sm in caries-active Uygur preschool children show apparent more genetic diversity than those in caries-free children. The genotypes of isolates might be related to differences in caries susceptibility.

Child, Preschool ; China ; ethnology ; Dental Caries ; ethnology ; microbiology ; Genetic Variation ; Genotype ; Humans ; Polymerase Chain Reaction ; Streptococcus mutans ; genetics ; isolation & purification ; Streptococcus sobrinus ; isolation & purification

OBJECTIVETo isolate and identify Streptococcus mutans (Sm) and Streptococcus sobrinus (Ss) in dental plaque of children with high dmft and no caries by selective medium, biochemical methods and arbitrarily primed-polymerase chain reaction (AP-PCR).

METHODSA total of 401 3-4-year-old children from seven kindergartens were recruited using cluster sampling and their dental caries status were examined. From 30% of children with the highest dmft score (dmft >/= 5), 20 children were chosen randomly as test group and 20 age and gender-matched caries-free children were selected as control. Plaque samples were collected from buccal surfaces of the molars and plated onto TYCSB plate. Sm and Ss were primarily identified by colony morphology and biochemical characteristics. Then chromosomal DNA of the strains was isolated and Sm or Ss were confirmed by AP-PCR.

RESULTSThe proportion positive for Sm and Ss in children with high dmft was 100% and 40% respectively while that in caries-free children was 75% and 5% by AP-PCR analysis. The differences were statistically significant between the two groups.

CONCLUSIONSThe proportions positive for Sm and Ss detected by AP-PCR method were significantly higher in children with high dmft than in caries-free children and it is a risk factor for high dmft in deciduous teeth harboring Sm and Ss.

Child, Preschool ; Dental Caries ; microbiology ; Dental Plaque ; microbiology ; Female ; Humans ; Male ; Streptococcus mutans ; genetics ; isolation & purification ; Streptococcus sobrinus ; genetics ; isolation & purification

Lysins are murein hydrolases produced by bacteriophage that act on the cell wall of host bacteria to release progeny phages. Research indicated that lysins could kill bacteria effectively and specifically in vitro. To prepare recombinant bacteriophage lysin of Streptococcus (PlyC) and analyze its biological activity, we obtained two genes of PlyC named PlyCA and PlyCB by PCR amplification and inserted them into pET-32a(+), then transformed the recombinant expression vectors pET-32a(+)-PlyCA and pET-32a(+)-PlyCB into E. coli BL21(DE3) respectively. After induction with 0.7 mmol/L IPTG at 30 degrees C for 7 h, PlyCA and PlyCB were successfully expressed, SDS-PAGE analysis determined that they all constituted above 30% of the total cell proteins. After Ni(2+)-NTA affinity chromatography, the purity was more than 95%. With the denaturation and protein refolding, we gained the recombinant PlyC. To determine its biological activity, we adopted turbidimetry and plate count method. Before and after lysin treatment, the cell morphology was studied by scanning electron microscopy (SEM). The results showed that the recombinant PlyC could specifically cleavage Streptococcus pyogenes (group A beta-hemolytic streptococci). Under the incubation time of 60 min with 4 microg/mL PlyC in Streptococcus pyogenes dilution which OD600 was 0.56, the germicidal effect was up to 99.6%, while SEM observations showed that cell wall cracked and presented cell debris. This finding laid the foundation for the further study and achieving an effective treatment for streptococcal infection.
Bacteriolysis ; Enzymes ; biosynthesis ; genetics ; isolation & purification ; Escherichia coli ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; Streptococcus pyogenes ; drug effects