title: Breakthrough in penicillin resistance? Streptococcus pneumoniae isolates with penicillin/cefotaxime MICs of 16 mg/L and their genotypic and geographical relatedness.
abstract: OBJECTIVE
  To phenotypically and genotypically characterize 11 strains (isolated in four different centres) exhibiting penicillin MIC of 8-32 mg/L among isolates of the SPICE project. Nine isolates were from Romania (9/162; 5.56%) and two from Poland (2/305; 0.66%).
  
  
  METHODS
  In vitro susceptibility was determined in triplicate by microdilution (CLSI guidelines), and additionally, MICs of penicillin, cefotaxime and amoxicillin were confirmed in triplicate by agar dilution. Multilocus sequence typing (MLST), PFGE and gene amplification and sequencing were performed.
  
  
  RESULTS
  For the nine Romanian isolates, MICs were >/=16 mg/L for penicillin, cefotaxime and amoxicillin, >/=32 mg/L for cefuroxime and cefpodoxime, 4-8 mg/L for cefditoren and >/=128 mg/L for erythromycin and gentamicin. All isolates were non-susceptible to imipenem (MIC = 0.5-1 mg/L) and susceptible to levofloxacin (MIC = 0.5-1 mg/L) and vancomycin (MIC = 0.25-0.5 mg/L). These Romanian strains presented a new cluster in the 595-600 region of PBP2X (YSGIQL-->LSTPWF) conferring 98% homology with Streptococcus mitis PBP2X, with a new MurM allele (seven strains) with eight amino acid changes versus R6. PBP nucleotide sequences were highly conserved suggesting a common origin. Allelic profiles of two strains gave sequence type 321, three strains exhibited a single- and four a double-locus variance. MLST-predicted serotype was 23F in all but one strain (19F), but three strains were 19A by Quellung.
  
  
  CONCLUSIONS
  The multidrug high resistance (precluding adequate oral therapy in children), its origin, the prevalence found in Romania and the presence of non-vaccine (7-valent) serotypes should worry the medical community because of a possible clonal diffusion that would limit therapeutic alternatives.
authors.affiliation: Department of Medical Microbiology and Antimicrobial Chemotherapy, Fundación Jiménez Díaz, Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Soriano
authors.forename: Fabio
authors.initials: F
authors.lastname: Cafini
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Aguilar
authors.forename: David
authors.initials: D
authors.lastname: Tarragó
authors.forename: Luis
authors.initials: L
authors.lastname: Alou
authors.forename: Maria-Jose
authors.initials: MJ
authors.lastname: Giménez
authors.forename: Matilde
authors.initials: M
authors.lastname: Gracia
authors.forename: Maria-Carmen
authors.initials: MC
authors.lastname: Ponte
authors.forename: Denisa
authors.initials: D
authors.lastname: Leu
authors.forename: Marina
authors.initials: M
authors.lastname: Pana
authors.forename: Iwona
authors.initials: I
authors.lastname: Letowska
authors.forename: Asuncion
authors.initials: A
authors.lastname: Fenoll
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D002439:Cefotaxime / Q000494:pharmacology*; D002648:Child; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins / Q000235:genetics; D010406:Penicillins / Q000494:pharmacology*; D011008:Pneumococcal Infections / Q000382:microbiology*; D011044:Poland; D012383:Romania; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D002439:Cefotaxime