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Oral lactam activity against recent (November2008June2009) penicillin non-susceptible serotype19A Streptococcus pneumoniae isolates in Spain

Abstract number: P1679

Fenoll A., Aguilar L., Gimenez M.J., Vicioso M.D., Robledo O., Granizo J.J., Coronel P.

Objective: To explore susceptibility to oral b-lactams vs. cefotaxime of penicillin (PEN) non-susceptible serotype 19A isolates since in Spain this serotype has significantly increased in last years after introduction of the 7-valent pneumococcal conjugate vaccine, with significant reduction in PEN susceptibility.

Methods: 268 successive PEN non-susceptible (MIC geqslant R: gt-or-equal, slanted0.12 mg/l) serotype 19A isolates received from November 2008 to June 2009 in the Spanish Reference Pneumococcal Laboratory were tested. Susceptibility was determined by agar dilution following CLSI, using Mueller-Hinton agar supplemented with 5% sheep blood, incubating under 5% CO2 atmosphere. CLSI breakpoints (oral for PEN and cefuroxime; non-meningitis for amoxicillin and cefotaxime) were used.

Results: MIC50, MIC90 (mg/l), range and percentage (%) of susceptible (S), intermediate (I) and resistant (R) isolates are shown in the table.

Conclusions: Cefditoren exhibited the highest intrinsic activity in terms of MIC50 and MIC90, with values four times lower than those of cefotaxime. Non-susceptibility (intermediate + resistant) rates to oral b-lactams with current CLSI breakpoints were high, ranging from 33.2% for amoxicillin to 98.9% for cefaclor.

 MIC50MIC90Range%S%I%R
PEN120.12–8-75.025.0
Amoxicillin18leqslant R: less-than-or-eq, slant0.06–3266.88.624.6
Cefaclorgeqslant R: gt-or-equal, slanted32geqslant R: gt-or-equal, slanted321–geqslant R: gt-or-equal, slanted321.11.197.8
Cefuroxime480.12–geqslant R: gt-or-equal, slanted3225.417.956.7
Cefpodoxime240.06–1625.410.164.6
Cefdinir480.06–1624.61.573.9
Cefditoren0.250.50.03–2***
Cefotaxime120.06–885.111.93.0
*No CLSI breakpoints available.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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