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

Abstract

Streptococcus criceti is a cariogenic organism that belongs to the mutans streptococci. Of the four S. criceti strains, strain OMZ 61 has been identified as being resistant to erythromycin. Antimicrobial susceptibility testing showed that strain OMZ 61 is also resistant to azithromycin, josamycin and clindamycin but susceptible to tetracycline and tiamulin. DNA hybridization analysis of the 23S rRNA genes revealed that the hybridization patterns in strain OMZ 61 differed from those in the other three strains. We further analyzed the nucleotide sequences of a ribosomal RNA operon, the rrnD operon, and the rpsJ−rpsQ region including rplC and rplD genes for ribosomal proteins L3 and L4, respectively, in the four strains studied. Nucleotide sequence analysis indicated that strain OMZ 61 contains an A-to-G substitution at nucleotide position 2059, equivalent to Escherichia coli numbering 2058, in a 23S rRNA gene (rrlD) and a G-to-A substitution at nucleotide position 439 in the rplC gene, suggesting an amino acid residue change at position 147 from valine to isoleucine, whereas no mutation in the rplD gene was found. DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism analysis showed that most or all of the 23S rRNA genes in strain OMZ 61 contain the A2059G mutation. These findings suggest that the resistance to erythromycin, azithromycin, josamycin and clindamycin in strain OMZ 61 is conferred by alterations in 23S rRNA and/or ribosomal protein L3. This is the first description of mutations in the 23S rRNA and rplC genes in mutans streptococci.

Antimicrobial Susceptibility Pattern of Helicobacter heilmannii and Helicobacter ailurogastricus Isolates

“…Similarly, point mutations in these ribosomal protein encoding genes have also been associated with acquired resistance to macrolides in Streptococcus criceti , S. pneumoniae , E. coli, and Brachyspira spp. [ 43 , 44 , 45 , 46 ]. Cross-resistance to more than one macrolide has been described in several bacterial species, such as Mycobacterium sp.…”

Comparative transcriptional profiling of tildipirosin-resistant and sensitive Haemophilus parasuis

“…RpsJ acts as general target of tigecycline adaption and a marker for alterations in antibiotic resistance in bacteria; the V57L mutation in rpsJ might cause weaker binding of tigecycline to 16S rRNA, leading to tigecycline resistance 45–48 . In RplD , encoding the ribosomal protein L4, it has also been found that the A2059G mutation confers resistance to macrolides and lincosamides 12, 49–51 . Other genes relative to ribosomes, encoding ribosomal proteins, are also concerned with resistance.…”