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Antimicrobial Agents and Chemotherapy, June 2006, p. 2098-2105, Vol. 50, No. 6
0066-4804/06/$08.00+0     doi:10.1128/AAC.00198-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Antimicrobial Susceptibility of Invasive Streptococcus pneumoniae Isolates in Portugal over an 11-Year Period

Antibiotic Resistance Unit, Centre of Bacteriology, National Institute of Health Dr. Ricardo Jorge, Lisbon, Portugal

Received 14 February 2006/ Returned for modification 20 March 2006/ Accepted 31 March 2006

This national surveillance study presents the in vitro activities of the main antimicrobial agents against 1,331 S. pneumoniae isolates as tested by an agar dilution method according to the guidelines of the Clinical and Laboratory Standards Institute (formerly NCCLS). The strains were isolated in several regions of Portugal from cases of invasive disease over an 11-year period (1994 to 2004). This study shows that the percentage of penicillin-nonsusceptible strains increased from 12% in 1994 to 28.5% in 2000. Then the rate declined to 17.7% in 2003 but increased again to 23.2% in 2004. Nevertheless, the rate of highly resistant isolates declined consistently, to 0.9% in 2001 to 2004. Ceftriaxone- and cefotaxime-nonsusceptible isolates became less frequent, from 4% and 8%, respectively, in 1994 to 1% in 2004. The macrolide-lincosamide-streptogramin B phenotype was the predominant macrolide phenotype found. The increase in the percentage of isolates that were only nonsusceptible to erythromycin (3.7% in 1994 to 1998 to 9.1% in 2002 to 2004) was similar to that for isolates with coresistance to penicillin and erythromycin (3.3% in 1994 to 1998 to 9.1% in 2002 to 2004). The nonsusceptibility to ciprofloxacin increased during recent years, from 0.5% in 2002 to 3.5% in 2004. Multidrug resistance also increased in recent years: from 7.9% in 2002 to 15.6% in 2004. The increasing use of macrolides could be causing the increase in penicillin and multidrug resistance, due to the coresistance to macrolides. The use of penicillin to treat empirical invasive pneumococci infections may need to be reconsidered.

This article has been cited by other articles:

• Dias, R., Felix, D., Canica, M. (2008). Diversity of Penicillin Binding Proteins among Clinical Streptococcus pneumoniae Strains from Portugal. Antimicrob. Agents Chemother. 52: 2693-2695 [Full Text]