title: Effect of penicillin G every three weeks on oral microflora by penicillin resistant Viridans Streptococci.
abstract: BACKGROUND
  Benzathine penicillin G every 3 weeks is the standard protocol for secondary prophylaxis for recurrent rheumatic fever.
  
  
  OBJECTIVE
  Assess the effect of Benzathine penicillin G on Streptococcus sanguinis and Streptococcus oralis in patients with cardiac valvular disease due to rheumatic fever receiving secondary prophylaxis.
  
  
  METHODS
  Oral streptococci were evaluated before (baseline) and after 7 days (day 7) with Benzathine penicillin G in 100 patients receiving routine secondary rheumatic fever prophylaxis. Saliva samples were evaluated for colony count and presence of S. sanguinis and S. oralis. Chewing-stimulated saliva samples were serially diluted and plated onto both nonselective and selective 5% sheep blood agar containing penicillin G. The species were identified using conventional biochemical tests. Minimal inhibitory concentrations were determined with the Etest.
  
  
  RESULTS
  No statistical differences were found in the presence of S. sanguinis comparing baseline and day 7 (p = 0.62). However, the existing number of positive cultures of S. oralis on day 7 after Benzathine penicillin G presented a significant increase compared to baseline (p = 0.04). No statistical difference was found between baseline and day 7 concerning the number of S. sanguinis or S. oralis CFU/mL and median minimal inhibitory concentrations.
  
  
  CONCLUSIONS
  This study showed that Benzathine penicillin G every 3 weeks did not change the colonization by S. sanguinis, but increased colonization of S. oralis on day 7 of administration. Therefore, susceptibility of Streptococcus sanguinis and Streptococcus oralis to penicillin G was not modified during the penicillin G routine secondary rheumatic fever prophylaxis.
authors.affiliation: Universidade de São Paulo, São Paulo, SP, Brazil. drandreaguiar@yahoo.com.br
authors.forename: André Andrade de
authors.initials: AA
authors.lastname: Aguiar
authors.forename: Roney Orismar
authors.initials: RO
authors.lastname: Sampaio
authors.forename: Jorge Luiz de Mello
authors.initials: JL
authors.lastname: Sampaio
authors.forename: Guilherme Sobreira
authors.initials: GS
authors.lastname: Spina
authors.forename: Ricardo Simões
authors.initials: RS
authors.lastname: Neves
authors.forename: Luiz Felipe Pinho
authors.initials: LF
authors.lastname: Moreira
authors.forename: Max
authors.initials: M
authors.lastname: Grinberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D002648:Child; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009055:Mouth / Q000382:microbiology*; D010400:Penicillin G / Q000008:administration & dosage*; D010403:Penicillin Resistance / Q000187:drug effects*; D012213:Rheumatic Fever / Q000517:prevention & control; D018709:Statistics, Nonparametric; D013997:Time Factors; D034363:Viridans Streptococci / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D010400:Penicillin G