In vitro interference of beta-lactams with biofilm development by prevalent community respiratory tract isolates.
Interference of cefditoren (CDN) and amoxicillin/clavulanic acid (AMC) with biofilm production was studied using 11 Streptococcus pneumoniae isolates with minimum inhibitory concentrations (MICs) ranging from 0.015microg/mL to 0.5microg/mL for CDN and from 0.06microg/mL to 2microg/mL for AMC (except for one isolate with an AMC MIC of 8microg/mL) and 5 Haemophilus influenzae isolates with MICs of 0.03-0.06microg/mL for CDN and 0.5-16microg/mL for AMC. Slime production was assessed in antibiotic-free medium and with 0.03microg/mL CDN or 1/0.5microg/mL AMC by measuring the optical density at 450nm (OD(450)). Significantly lower mean OD(450) values were obtained for S. pneumoniae with antibiotics compared with controls (CDN, 0.088 vs. 0.118, P=0.003; and AMC, 0.095 vs. 0.112, P=0.003), with significant correlation between both antibiotics (r=0.752; P=0.008). Percent reduction in OD(450) values was higher for CDN compared with AMC (24.02% vs. 15.92%; P=0.008). For H. influenzae, significantly lower mean OD(450) values were obtained with CDN compared with controls (0.083 vs. 0.096; P=0.043) but not with AMC (0.086 vs. 0.095; P=0.08). Comparing percent reductions in S. pneumoniae versus H. influenzae for each antibiotic, no differences were found for AMC (15.92% vs. 9.40%; P=0.36), with a tendency for CDN (24.02% vs. 13.79%; P=0.069). Different beta-lactams may have different capabilities of interfering with S. pneumoniae biofilm development when tested under the same experimental conditions.
Maestre
J R
JR
Microbiology Department, Hospital Central de la Defensa Gómez-Ulla, Gta. del Ejército s/n, 28007 Madrid, Spain.
Mateo
M
M
Méndez
M L
ML
Aguilar
L
L
Gimenez
M J
MJ
Alou
L
L
Coronel
P
P
Granizo
J J
JJ
Prieto
J
J
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D005838:Genotype; D006193:Haemophilus influenzae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D012137:Respiratory System / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000382:microbiology; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology*; D047090:beta-Lactams / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D047090:beta-Lactams