Antimicrobial resistance among respiratory pathogens in Spain: latest data and changes over 11 years (1996-1997 to 2006-2007)

Abstract

A nationwide multicenter susceptibility surveillance study (Susceptibility to the Antimicrobials Used in the Community in España [SAUCE] project), SAUCE-4, including 2,559 Streptococcus pneumoniae, 2,287 Streptococcus pyogenes, and 2,736 Haemophilus influenzae isolates was carried out from May 2006 to June 2007 in 34 Spanish hospitals. Then, the results from SAUCE-4 were compared to those from all three previous SAUCE studies carried out in 1996-1997, 1998-1999, and 2001-2002 to assess the temporal trends in resistance and the phenotypes of resistance over the 11-year period. In SAUCE-4, on the basis of the CLSI breakpoints, penicillin (parenteral, nonmeningitis breakpoint) and cefotaxime were the antimicrobials that were the most active against S. pneumoniae (99.8% and 99.6%, respectively). Only 0.9% of isolates had a penicillin MIC of > or = 2 microg/ml. In S. pyogenes, nonsusceptibility to erythromycin was observed in 19.4% of isolates. Among the H. influenzae isolates, a beta-lactamase-positive prevalence of 15.7% was found. A statistically significant temporal decreasing trend over the 11-year period was observed for nonsusceptibility (from 60.0% to 22.9%) and resistance (from 36.5% to 0.9%) to penicillin and for the proportion of erythromycin-resistant isolates of S. pneumoniae of the macrolide-lincosamide-streptogramin B (MLS(B)) phenotype (from 98.4% to 81.3%). A similar trend was observed for the prevalence of ampicillin resistance (from 37.6% to 16.1%), beta-lactamase production (from 25.7% to 15.7%), and beta-lactamase-negative ampicillin resistance (BLNAR) in H. influenzae (from 13.5% to 0.7%). Among erythromycin-resistant isolates of S. pyogenes, a significant increasing trend in the prevalence of MLS(B) was observed (from 7.0% to 35.5%). SAUCE-4 confirms a generalized decline in the resistance of the main respiratory pathogens to the antimicrobials as well as a shift in their resistance phenotypes.

FIG. 1.

Temporal trends in penicillin resistance, erythromycin resistance, and ciprofloxacin resistance in S. pneumoniae in Spain (percentage of clinical isolates). Symbols: solid line with filled triangles, nonsusceptibility to penicillin; dashed line with open squares, resistance to erythromycin; solid lines with filled diamonds, resistance to penicillin (MIC ≥ 2 μg/ml); dashed lines with open circles, resistance to ciprofloxacin. SAUCE-1, 1996-1997; SAUCE-2, 1998-1999; SAUCE-3, 2001-2002; SAUCE-4, 2006-2007. P < 0.001 for all comparisons of SAUCE-4 with previous SAUCE studies.

FIG. 2.

Temporal trends in erythromycin resistance and the MLS_B phenotype in S. pyogenes in Spain (percentage of clinical isolates). Symbols: dashed line with squares, percentage of erythromycin-resistant isolates with the MLS_B phenotype; solid line with diamonds, resistance to erythromycin. SAUCE-1, 1996-1997; SAUCE-2, 1998-1999; SAUCE-3, 2001-2002; SAUCE-4, 2006-2007. P < 0.001 for comparisons of SAUCE-4 with SAUCE-3.

FIG. 3.

Temporal trends in prevalence of resistance to ampicillin and phenotypes of resistance in H. influenzae in Spain (percentage of clinical isolates). Symbols: solid line with diamonds, resistance to ampicillin; dashed line with squares, β-lactamase production; dashed line with triangles, BLNAR (ampicillin MIC ≥ 2 μg/ml). In SAUCE-4, there were 134 isolates (4.9%) with mutations in the ftsI gene exhibiting ampicillin MICs between 0.5 and 1 μg/ml and amoxicillin-clavulanate MICs of ≥2 μg/ml. SAUCE-1, 1996-1997; SAUCE-2, 1998-1999; SAUCE-3, 2001-2002; SAUCE-4, 2006-2007. P < 0.001 for all comparisons of SAUCE-4 with previous SAUCE studies.