title: Antimicrobial susceptibility of invasive Streptococcus pneumoniae isolates in Portugal over an 11-year period.
abstract: 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 < or =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.
authors.affiliation: Antibiotic Resistance Unit, Centre of Bacteriology, National Institute of Health Dr. Ricardo Jorge, Lisbon, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Dias
authors.forename: Deolinda
authors.initials: D
authors.lastname: Louro
authors.forename: Manuela
authors.initials: M
authors.lastname: Caniça
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D002439:Cefotaxime / Q000627:therapeutic use; D002701:Chloramphenicol / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000627:therapeutic use; D002981:Clindamycin / Q000627:therapeutic use; D018432:Drug Resistance, Multiple; D004917:Erythromycin / Q000627:therapeutic use; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000627:therapeutic use; D010403:Penicillin Resistance / Q000235:genetics; D010406:Penicillins / Q000494:pharmacology* / Q000627:therapeutic use; D011159:Population Surveillance; D011174:Portugal / Q000453:epidemiology; D012189:Retrospective Studies; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D013752:Tetracycline / Q000627:therapeutic use; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use; D014640:Vancomycin / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D010406:Penicillins; D002981:Clindamycin; D002939:Ciprofloxacin; D004917:Erythromycin; D002701:Chloramphenicol; D014640:Vancomycin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D015242:Ofloxacin; D013752:Tetracycline; D002439:Cefotaxime