• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1345-1351
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• 2011

Vancomycin therapy failure due to the emergence of tolerance in pneumococci is increasing. The molecular mechanism of tolerance is not clear, but lytA and $pep^{27}$ are known to be involved. Our aim was to evaluate the expression of both genes in vancomycin-tolerant Streptococcus pneumoniae (VTSP) strains. Eleven VTSP strains from a total of 309 clinical isolates of S. pneumoniae from 1997 to 2006 were classified according to the criteria of Liu and Tomasz. All VTSP strains were evaluated for susceptibility according to CLSI criteria, serotype by the Quellung test, and clonality by PFGE. The expressions of lytA and $pep^{27}$ were analyzed in different growth phases by RT-PCR with and without vancomycin. Eighty-two percent of VTSP strains showed resistance to penicillin, and 100% were sensitive to vancomycin and cefotaxime. The most frequent serotypes of VTSP strains were 23F (4/11) and 6B (3/11). Clonal relationship was observed in only two strains. No significant changes were observed in $pep^{27}$ expression in the three phases of growth in VTSP strains with and without vancomycin. Interestingly, $pep^{27}$ expression in the stationary phase in the non-tolerant reference strain R6 was significantly higher. However, no significant differences in lytA expression were observed between VTSP and R6 strains during the phases of growth analyzed. The absence of changes in $pep^{27}$ expression in VTSP strains in the stationary phase may be related to their ability to tolerate high antibiotic concentrations, and thus, they survive and remain in the host under the antibiotic selective pressure reflected in therapeutic failure.

• Pediatric Infection and Vaccine
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• v.13 no.2
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• pp.99-105
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• 2006

Purpose : The serotyping results of the Quellung reaction was compared with the newly developed multiplex latex assay and the sensitivity of the Quellung reaction was compared. Methods : We checked the serotypes of 35 samples obtained from patients treated at Yonsei University Medical Center using the multiplex latex bead method and compared the results with the serotypes previously obtained via the Quellung reaction. Results : A decrease in the mean fluorescence was detected in the samples tested with the multiplex assay. Seventeen samples out of the 27 samples agreed to the results of the Quellung assay. We were only able to confirm the concordance of 11 serotypes out of 14 serotypes available. Conclusion : The Quellung reaction is time consuming procedure and prone to errors even with expertise in the procedure, and other alternate methods in serotyping have been investigated to overcome these problems. The newly developed multiplex latex bead assay can test more samples at the same time and has a higher degree of sensitivity. A large scale trial is required to test the sensitivity of the new assay across various serotypes along with efforts to increase the sensitivity of the Quellung assay. The preliminary data suggests that this method may be widely used.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.62-65
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• 2003

A procedure to increase the stability of 6B capsular polysaccharide on microbead surface in the mutibead assay, a serotyping method for Streptococcus pneumoniae, was studied. Pneumococcal capsular polysaccharide 6B was conjugated to bvine serum albumin (BSA), and the coating efficiency and the stability of the 6B-BSA complex was measured. The 6B-BSA complex showed about 200-fold higher coating efficiency to polystyrene surface than 6B polysaccharide. And the stability of the 6B- BSA to be used in the multibead assay for 30 days after coating.

• Clinical and Experimental Pediatrics
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• v.55 no.11
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• pp.424-429
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• 2012

Purpose: Methods for quick and reliable detection of Streptococcus pneumoniae are needed for the diagnosis of pneumococcal disease and vaccine studies. This study aimed to show that sequential multiplex polymerase chain reaction (PCR) is more efficient than conventional culture in achieving S. pneumoniae -positive results. Methods: Nasopharyngeal (NP) secretions were obtained from 842 pediatric patients admitted with lower respiratory infections at Severance Children's Hospital in Korea between March 2009 and June 2010. For identification and serotype determination of pneumococci from the NP secretions, the secretions were evaluated via multiplex PCR technique with 35 serotype-specific primers arranged in 8 multiplex PCR sets and conventional bacteriological culture technique. Results: Among the results for 793 samples that underwent both bacterial culture and PCR analysis for pneumococcal detection, 153 (19.3%) results obtained by PCR and 81 (10.2%) results obtained by conventional culture technique were positive for S. pneumoniae. The predominant serotypes observed, in order of decreasing frequency, were 19A (23%), 6A/B (16%), 19F (11%), 15B/C (5%), 15A (5%), and 11A (4%); further, 26% of the isolates were non-typeable. Conclusion: As opposed to conventional bacteriological tests, PCR analysis can accurately and rapidly identify pneumococcal serotypes.

• Pediatric Infection and Vaccine
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• v.2 no.2
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• pp.194-199
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• 1995

Most boys afflicted with panhypogammaglobulinemia, also known as X-linked agammaglobulinemia, remain healthy during the first 6 to 12 months of life because of protection by maternally transmitted IgG antibodies. Thereafter, they repeatedly acquire infections with high-grade pathogens, such as pneumococci, streptococci, and hemophilus unless given antibiotics or immunoglobulin replacement therapy. We experienced a case of panhypogammaglobulinemia in a 4 years old boy. He had been suffered from recurrent upper respiratory tract infection, otitis media and pneumonia since late infancy. He was admitted due to right pleural effusion with pneumonia, and streptococcus pneumoniae was isolated from pleural fluid and blood cultures. His immune status revealed panhypogammaglobulinemia and deficiency in mature B lymphocyte. He was treated with appropriate antibiotics therapy, but showed poor responses. He was transferred to department of thoracic surgery, and received minithoracotomy (decortication) operation. He was successfully treated with operation, antibiotics, and IV gammaglobulin infusions. Now he is being followed with periodic IV gammaglobulin replacement therapy.

• The Journal of the Korean Society for Microbiology
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• v.35 no.2
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• pp.109-115
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• 2000

FtsH is a membrane-bound, ATP-dependent metalloprotease that is involved in a variety of cellular functions including the regulation of responses to heat and stress shock. Previously, we had cloned and sequenced pneumococcal ftsH gene whose deduced amino acid sequence was very similar to those of several gram-positive bacteria and Escherichia coli, except for the N-terminal domain that was responsible for membrane anchoring. In order to better understand the role of Streptococcus pneumoniae FtsH, we expressed pneumococcal ftsH gene in Escherichia coli. When it was expressed from a strong promoter, $P_{tac}$, a considerable amount of the recombinant FtsH was produced, although the prolonged induction resulted in not only accumulation of breakdown products but also ceasing of the further growth of E. coli host. This indicated that the expression of the exogenous ftsH gene was tightly regulated since the excessive FtsH appeared detrimental to bacterial cells. In Western blotting, the pneumococcal FtsH protein, whether native or recombinant, was reactive to anti-E. coli FtsH serum. The observation that FtsH proteins were well conserved throughout the bacterial kingdom and its expression level was fine-tuned suggests an important role for this protein in the stress adaptation which may be related to infecting process by pneumococci.

• Molecules and Cells
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• v.19 no.3
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• pp.365-374
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• 2005

To find potential targets of novel antimicrobial agents, we identified essential genes of Streptococcus pneumoniae using comparative genomics and allelic replacement mutagenesis. We compared the genome of S. pneumoniae R6 with those of Bacillus subtilis, Enterococcus faecalis, Escherichia coli, and Staphylococcus aureus, and selected 693 candidate target genes with > 40% amino acid sequence identity to the corresponding genes in at least two of the other species. The 693 genes were disrupted and 133 were found to be essential for growth. Of these, 32 encoded proteins of unknown function, and we were able to identify orthologues of 22 of these genes by genomic comparisons. The experimental method used in this study is easy to perform, rapid and efficient for identifying essential genes of bacterial pathogens.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.5 no.1
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• pp.83-87
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• 2002

Primary peritonitis usually refers to a bacterial infection of the peritoneal cavity without a demonstrable intra-abdominal source. Most cases occur in children with ascites resulting from nephrotic syndrome or cirrhosis. Rarely, it may occur in previously healthy children less than 7years of age, usually a girl. Distinguishing primary peritonitis from appendicitis may be impossible in patients without a history of nephrotic syndrome or cirrhosis. Accordingly, the diagnosis of primary peritonitis is made only at laparotomy. We report one case of primary pneumococcal peritonitis in a 27-month-old female who underwent explorative laparotomy to discover the cause of suspicious intestinal perforation and mechanical ileus. Later, pneumococci were cultured in blood and gram-positive diplococci were isolated from the pus of peritoneal cavity.

• Molecules and Cells
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• v.21 no.1
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• pp.82-88
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• 2006

The global pattern of growth-dependent gene expression in Streptococcus pneumoniae strains was evaluated using a high-density DNA microarray. Total RNAs obtained from an avirulent S. pneumoniae strain R6 and a virulent strain AMC96-6 were used to compare the expression patterns at seven time points (2.5, 3.5, 4.5, 5.5, 6.0, 6.5, and 8.0 h). The expression profile of strain R6 changed between log and stationary growth (the Log-Stat switch). There were clear differences between the growth-dependent gene expression profiles of the virulent and avirulent pneumococcal strains in 367 of 1,112 genes. Transcripts of genes associated with bacterial competence and capsular polysaccharide formation, as well as clpP and cbpA, were higher in the virulent strain. Our data suggest that late log or early stationary phase may be the most virulent phase of S. pneumoniae.

• Biomolecules & Therapeutics
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• v.18 no.3
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• pp.271-279
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• 2010

Streptococcus pneumoniae is the major pathogen that frequently causes serious infections in children, the elderly and immunocompromised patients. S. pneumoniae is known to produce reactive oxygen species (ROS) and S. pneumoniae-produced ROS is considered to play a role in pneumococci pathogenesis. SIGN-R1 is the principal receptor of capsular polysaccharides (CPSs) of S. pneumoniae. However, there is a considerable lack of knowledge about the protective role of SIGN-R1 against S. pneumoniae-produced ROS in SIGN-$R1^+$ macrophages. While investigating the protective role of SIGN-R1 against ROS, we found that SIGN-R1 intimately bound to peroxiredoxin-1 (Prx-1), one of small antioxidant proteins in vitro and in vivo. This interaction was increased with ROS generation which was produced by stimulating SIGN-R1 with dextran, a polysaccharide ligand of SIGN-R1. Also, SIGN-R1 crosslinking with 22D1 anti-SIGN-R1 antibody increased Prx-1 in vitro or in vivo. These results suggested that SIGN-R1 stimulation with CPSs of S. pneumoniae increase the expression level of Prx-1 through ROS and its subsequent interaction to SIGN-R1, providing an important antioxidant role for the host protection against S. pneumoniae.