This study assesses a novel bile solubility test and MALDI-TOF for the differentiation of Streptococcus pneumoniae from other mitis group streptococci, including differentiation of S. pneumoniae from Streptococcus pseudopneumoniae. Eighty-four species verified mitis group isolates were subjected to our bile solubility test (which measures and calculates the differences of absorbance in the test tube containing 10% sodium deoxycholate versus a blank control tube, after incubation for 10 minutes at 36 degrees C using a spectrophotometer) and MALDI-TOF MS (both the standard result output and by visual spectra evaluation). Applying a calculated optimal cut-off absorbance-value of 2.1, differentiated S. pneumoniae from all but one other mitis group streptococci (one S. mitis isolate generated an OD-value above 2.1). MALDI-TOF score value identification identified correctly 46 S. pneumoniae and 4 S. pseudopneumoniae but misidentified 16 other mitis group strains. Visual spectra evaluation correctly identified all S. pneumoniae and S. pseudopneumoniae strains but misidentified 13 other mitis group strains. The bile solubility test based on spectrophotometric reading described in this study can differentiate S. pneumoniae from other Streptococcus species. Combining the bile solubility test and the MALDI-TOF spectra results provide a correct identification of all S. pneumoniae and S. pseudopneumoniae isolates.

Ninety-seven animal, human, and dairy Streptococcus porcinus or Streptococcus pseudoporcinus isolates in the CDC Streptococcus strain collection were evaluated based on DNA-DNA reassociation, 16S rRNA and rpoB gene sequencing, conventional biochemical and rapid ID 32 STREP identification methods, and antimicrobial susceptibility testing to determine their taxonomic status, characteristics for species differentiation, antimicrobial susceptibility and relevance of clinical source. Nineteen of the 97 isolates (1 human, 18 swine) were identified as S. porcinus. The remaining 72 human isolates and 6 dairy isolates were identified as S. pseudoporcinus. The use of 16S rRNA or rpoB gene sequencing was required to differentiate S. porcinus from S. pseudoporcinus. The human and dairy S. pseudoporcinus isolates were biochemically distinct from each other as well as distinct by 16S rRNA and rpoB gene sequencing. Therefore, we propose the subspecies denominations S. pseudoporcinus subsp. hominis subsp. nov. for the human isolates and S. pseudoporcinus subsp. lactis subsp. nov. for the dairy isolates. Most strains were susceptible to the antimicrobials tested, with the exception of tetracycline. Two strains of each species were also resistant to clindamycin and erythromycin and carried the erm(A) (S. pseudoporcinus) or the erm(B) (S. porcinus) genes. S. porcinus was identified from a single human isolate recovered from a wound in an abattoir worker. S. pseudoporcinus was primarily isolated from the genitourinary tract of women, but was also associated with blood, placental, and wound infections. Isolates reacting with group B antiserum and demonstrating wide beta hemolysis should be suspected of being S. pseudoporcinus and not S. agalactiae.

Several of the more recently proposed new species of Enterococcus are nearly identical based on 16S rDNA sequence analysis and phenotypic traits. In the present study, DNA-DNA reassociation experiments, in conjunction with sequencing of the 16S rRNA and rpoB genes, provided evidence that "Enterococcus sanguinicola" and Enterococcus thailandicus actually represent the same species. In contrast, Enterococcus caccae and Enterococcus silesiacus, two other species with nearly identical 16S rRNA gene sequences were confirmed as separate species.

OBJECTIVE: Because 7-valent pneumococcal conjugate vaccine (PCV7) is highly efficacious, pneumococcal infections in vaccinated children raise concerns about immunologic disorders. We characterized a case series of US children in whom invasive pneumococcal infections developed despite vaccination. STUDY DESIGN: We reviewed invasive (sterile site) pneumococcal infections in children aged <5 years who had received ≥1 PCV7 dose as identified from October 2001 to February 2004 through national passive surveillance and the Centers for Disease Control and Prevention's Active Bacterial Core surveillance. Vaccine serotype infections were considered breakthrough cases; the subset of breakthrough cases occurring in children who completed an age-appropriate vaccination series were considered PCV7 failures. RESULTS: We identified 753 invasive infections; 155 infections (21%) were breakthrough cases, predominantly caused by serotypes 6B (n = 50, 32%) and 19F (n = 45, 29%). The proportion of breakthrough cases decreased with the increasing number of PCV7 doses received (P < .001, X(2) for linear trend). Children with co-morbid conditions accounted for 31% of breakthrough infections. Twenty-seven cases (4%) were classified as vaccine failures. Most failures (71%) occurred in children who were vaccinated according to catch-up schedules; 37% had co-morbid conditions. CONCLUSION: Invasive pneumococcal infections identified in vaccinated U.S. children were primarily caused by disease resulting from serotypes not covered with PCV7, rather than failure of the vaccine. Incomplete vaccination and co-morbid conditions likely contribute to breakthrough vaccine-type pneumococcal infections.