JAC Advance Access originally published online on June 11, 2007
Journal of Antimicrobial Chemotherapy 2007 60(2):323-327; doi:10.1093/jac/dkm209
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Influence of the ß-lactam resistance phenotype on the cefuroxime versus cefditoren susceptibility of Streptococcus pneumoniae and Haemophilus influenzae recovered from children with acute otitis media
1 Spanish National Reference Pneumococcal Laboratory, Instituto de Salud Carlos III, ctra. Majadahonda-Pozuelo Km. 2, 28220 Majadahonda, Madrid, Spain 2 Microbiology Department, School of Medicine, Univ. Complutense, Avda. Complutense s/n, 28040 Madrid, Spain 3 Granadatos SL, c/Demetrio de la Guerra 4, 28223 Pozuelo de Alarcón, Madrid, Spain 4 Scientific Department, Tedec-Meiji Farma S.A., Madrid, Spain
Received 10 April 2007; returned 24 April 2007; revised 7 May 2007; accepted 14 May 2007
* Corresponding author. Tel: +34-91-8223664; E-mail: afenoll{at}isciii.es
Objectives: To study the influence of resistance phenotypes (based on sentinel antibiotics: penicillin and amoxicillin with/without clavulanate) on the cefuroxime versus cefditoren susceptibility of Streptococcus pneumoniae and Haemophilus influenzae recovered from children with acute otitis media.
Methods: Middle ear isolates (193 S. pneumoniae and 114 H. influenzae) received in the Spanish Reference Laboratory (Instituto de Salud Carlos III) were tested. Antimicrobial susceptibility to penicillin, amoxicillin with/without clavulanate, cefuroxime and cefditoren was determined by agar dilution using Mueller–Hinton agar supplemented with 5% sheep blood for S. pneumoniae and Haemophilus Test Medium for H. influenzae. Strains were classified according to penicillin susceptibility (S. pneumoniae) or ß-lactamase production (H. influenzae).
Results: The decrease in penicillin susceptibility of S. pneumoniae (from the susceptible to the resistant category) decreased amoxicillin and cefuroxime susceptibility rates from 100% to 34% and 0%, respectively. All pneumococcal strains were inhibited by 0.5 mg/L cefditoren, including those from penicillin-resistant serotypes 14, 23F, 6B and 9V with higher amoxicillin versus penicillin MICs. Susceptibility rates of ß-lactamase-positive H. influenzae strains were 93.8% and 85.4% to amoxicillin/clavulanate and cefuroxime, respectively. Resistance to amoxicillin/clavulanate (MIC 
8/4 mg/L) was 12.1% (8 out of 66) and 6.3% (3 out of 48) in ß-lactamase-negative and -positive strains, respectively. All H. influenzae strains were inhibited by 
0.06 mg/L cefditoren.
Conclusions: Susceptibility to sentinel ß-lactams cannot predict activity of other members of the group. The addition of clavulanic acid to amoxicillin does not guarantee 100% coverage of H. influenzae, regardless of ß-lactamase production.
Keywords: antimicrobial susceptibility , paediatric isolates , middle ear isolates , amoxicillin resistance
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. Torrico, L. Aguilar, N. Gonzalez, M. J. Gimenez, O. Echeverria, F. Cafini, D. Sevillano, L. Alou, P. Coronel, and J. Prieto Influence of TEM-1 {beta}-Lactamase on the Pharmacodynamic Activity of Simulated Total versus Free-Drug Serum Concentrations of Cefditoren (400 Milligrams) versus Amoxicillin-Clavulanic Acid (2,000/125 Milligrams) against Haemophilus influenzae Strains Exhibiting an N526K Mutation in the ftsI Gene Antimicrob. Agents Chemother., October 1, 2007; 51(10): 3699 - 3706. [Abstract] [Full Text] [PDF]
|
|