title: New susceptibility breakpoints in antimicrobial resistance rates of invasive pneumococcal strains.
abstract: OBJECTIVE
  To evaluate the impact of new penicillin susceptibility breakpoints on resistance rates of pneumococcal strains collected from children with pneumonia.
  
  
  METHODS
  Pneumococcal strains collected from patients admitted with pneumonia were isolated at the clinical analysis lab of Hospital de Clínicas de Uberlândia, Uberlândia, Brazil, and sent to Instituto Adolfo Lutz, São Paulo, Brazil, for further identification, serotyping and determination of antimicrobial susceptibility.
  
  
  RESULTS
  From April 1999 to December 2008, 330 strains of pneumococcus were sent to Instituto Adolfo Lutz; of these, 195 (59%) were collected from patients with pneumonia. One hundred strains collected from patients < or = 12 years old were analyzed. The patients' age ranged from 1 to 12.6 years old (with mean age of 2.4 and median of 1.7 years). Forty-seven patients were male. The strains were isolated from blood (42%) and pleural fluid (58%). There were 35 oxacillin-resistant strains: according to the criteria defined by the Clinical and Laboratory Standards Institute (CLSI) in 2007 [minimum inhibitory concentration (MIC) < or = 0.06 microg/mL for susceptibility (S), 0.12 to 1 microg/mL for intermediate resistance (IR), and > or = 2 microg/mL for full resistance (FR)], 22 strains had IR and 11 strains had FR. According to the current breakpoints defined by the CLSI in 2008 (< or = 2 microg/mL for S, 4 microg/mL for IR and > or = 8 microg/mL for FR), only one strain had IR to penicillin. There was resistance to co-trimoxazole (80%), tetracycline (21%), erythromycin (13%), clindamycin (13%), and ceftriaxone (one strain simultaneously resistant to penicillin).
  
  
  CONCLUSIONS
  When the new breakpoints for in vitro susceptibility were applied, penicillin resistance rates dropped 97%, from 33 to 1%.
authors.affiliation: Faculdade de Medicina, Universidade Federal de Uberlândia (UFU), Uberlândia, MG, Brazil.
authors.forename: Paula Carolina Bejo
authors.initials: PC
authors.lastname: Wolkers
authors.forename: Orlando Cesar
authors.initials: OC
authors.lastname: Mantese
authors.forename: Alan de
authors.initials: Ad
authors.lastname: Paula
authors.forename: Vivieni Vieira Prado
authors.initials: VV
authors.lastname: Almeida
authors.forename: Paula Augusta Dias Fogaça de
authors.initials: PA
authors.lastname: Aguiar
authors.forename: Jackelline Rodrigues
authors.initials: JR
authors.lastname: Alvares
authors.forename: Samanta Cristine Grassi
authors.initials: SC
authors.lastname: Almeida
authors.forename: Maria Cristina de Cunto
authors.initials: MC
authors.lastname: Brandileone
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000145:classification / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D010406:Penicillins / Q000145:classification / Q000494:pharmacology*; D035422:Pleural Cavity / Q000382:microbiology; D011018:Pneumonia, Pneumococcal / Q000097:blood / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins