Characterization of <i>Streptococcus criceti</i> insertion sequence IS<i>Scr1</i>

Abstract

A novel insertion sequence element of the IS982 family, ISScr1, was previously identified in Streptococcus criceti strain E49 as a disrupted paaB gene encoding an antigen I/II homologous protein. In this study, we identified two divergent inserted regions of ISScr1 in S. criceti E49 by inverse polymerase chain reaction, the gene-walking method, and screening of the partial plasmid library. Nucleotide sequence analysis indicated the possible explanation that transposition generated 8-and 9-bp direct repeat sequences. DNA hybridization analysis revealed that an identical hybridization pattern to ISScr1 was observed in the four S. criceti strains studied and that at least three copies of ISScr1 were preserved in S. criceti strains. In addition, we found different susceptibility to erythromycin and diverse agglutination properties induced by dextran in S. criceti. Furthermore, DNA hybridization analysis showed that no ISScr1-like copy was detected in the other 14 strains of oral streptococci tested.

Molecular characterization of the dextran-binding lectin B gene <i>dblB</i> of <i>Streptococcus criceti</i> in <i>Streptococcus mutans</i> strain GS-5 with mutations in both <i>gbpC</i> and <i>spaP</i> genes

“…The agglutination assay was performed by modifying a method described previously (Tamura et al, 2012). Bacterial cells cultured anaerobically at 37°C for 16 h in BHI broth were washed three times with phosphate-buffered saline (PBS).…”

“…However, it is not known how dextran-induced agglutination occurs in S. criceti. Furthermore, dextran-induced agglutination ability varies in S. criceti strains: agglutination-positive strains are HS-6 T and OMZ 61, and agglutination-negative strains are E49 and HS-1 (Tamura et al, 2012). dblA and dblB genes encoding 1,093-and 1,717-amino-acid proteins, respectively, have been identified in strain HS-6 T (Kojima et al, 2012), but nucleotide sequences of the dblA and dblB genes have not been determined in strains E49, HS-1 or OMZ 61.…”

“…Our previous work showed that dextran-induced agglutination-negative strains were S. criceti strains E49 and HS-1 and S. sobrinus OMZ 65 (Tamura et al, 2012). In other non-agglutinating strains of S. sobrinus, changes in the dblB gene have been identified: strain OMZ 176, which possesses truncated DblA (584 residues) and DblB (254 residues), has mutations comprising a single adenine nucleotide insertion in the dblA gene and a 736-nucleotide deletion in dblB; and strain B-13N, which produces DblA (1,270 residues) but lacks DblB, shows replacement of the dblB gene by an IS1548-like sequence (Sato et al, 2009).…”

Identification of A2059G 23S rRNA and G439A <i>rplC</i> gene mutations in <i>Streptococcus criceti</i> strain OMZ 61, a strain resistant to azithromycin, josamycin and clindamycin

“…Recently, it has been proposed from genomic analysis that S. criceti and S. downei be grouped into a clade distinct from the mutans group (Richards et al, 2014). In a previous study using four S. criceti strains, we found that strains HS-6 T , HS-1 and E49 were susceptible to erythromycin, but strain OMZ 61 was resistant to the antibiotic (Tamura et al, 2012). Strain OMZ 61 was isolated from a high-sucrose diet-fed rat, and was subsequently habituated to erythromycin by serial passage in broth containing increasing levels of erythromycin, up to 1,000 μg/ml (Guggenheim et al, 1965).…”

“…As we previously observed that only strain OMZ 61 showed resistance to erythromycin (14-membered-ring group) among the four S. criceti strains studied (Tamura et al, 2012), we further examined other antibiotics including the 15-and 16-membered-ring macrolides azithromycin and josamycin, respectively, and clindamycin (Table 2). There were marked differences in the MICs of azithromycin, josamycin and clindamycin for the four strains: OMZ 61 exhibited high resistance (MICs: 2000, > 80 and 7.36 μg/ml, respectively), but the others were susceptible (MICs: 0.40, 0.20 and 0.015−0.030 μg/ml, respectively).…”