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

Abstract

Streptococcus pneumoniae is an important pathogen responsible for serious invasive diseases, including meningitis and septicemia. The spread of multidrug-resistant (MDR) pneumococci has become a worldwide problem, making treatment more difficult (18). Indeed, in addition to resistance to penicillin, resistance to other antibiotics, including erythromycin, tetracycline, and chloramphenicol, has emerged and is spreading (10).Since 1989, the National Institute of Health Dr. Ricardo Jorge reference laboratory has been continually monitoring the in vitro activity of antimicrobial agents against S. pneumoniae collected from invasive sources. This program for monitoring susceptibility to antibiotics in Portugal (ARSIP) provides a unique collection of Portuguese pneumococcal isolates. This national surveillance study reported that 4.6% of isolates were penicillin nonsusceptible in 1989, and this value remained generally stable until 1991 (6.4%) (32). Fully penicillin-resistant isolates (MIC of 2 g/ml) were reported for the first time in 1992 (0.8%) and made up 5.5% of isolates in the following year (32).Here, we describe the surveillance of pneumococci by the reference laboratory in Portugal. We report the in vitro activities of different antimicrobial agents used against S. pneumoniae isolated from invasive sources over 11 years (from 1994 to 2004). MATERIALS AND METHODSPatients and bacterial isolates. Between 1 January 1994 and 31 December 2004, the ARSIP survey conducted by the Antibiotic Resistance Unit (ARU) from the National Institute of Health Dr. Ricardo Jorge constantly monitored pneumococcal isolates from cases of invasive disease in various regions of Portugal. The national laboratory-based surveillance system collected 1,331 invasive pneumococcal strains, which were isolated in 24 bacteriology laboratories in hospitals and public health institutions. In the period 1994 to 1998, 12 hospitals participated in the study, and since 1999, 12 more hospitals have been added to the network. Isolates were included if they were nonrepetitive or consecutive blood, cerebrospinal fluid (CSF), or pleural fluid samples from patients with symptoms compatible with invasive pneumococcal disease. No changes were made to the methods of data collection during the study. Some isolates were from outpatients, but most were from patients hospitalized with communityacquired invasive pneumococci disease. Only one isolate per patient was considered. Patients over 15 years old were considered to be adults.Identification and serotyping. The isolates were sent at Ϫ20°C by hospital laboratories to the reference laboratory, ARU, in Trypticase soy broth (TSB; Oxoid, Basingstoke, England) containing 20% glycerol. On reception by the ARU, the purity of the pneumococcal isolate was checked using standard methods, and the isolate was then stored at Ϫ80°C in TSB containing 20% glycerol. Isolates were serotyped by dot blotting, the Quellung reaction, or both (11).Antimicrobial susceptibility testing. Susceptibility testing was performed by the aga...

Temporal Trends of Antimicrobial Resistance and Clonality of Invasive Streptococcus pneumoniae Isolates in Finland, 2002 to 2006

“…The highest antimicrobial nonsusceptibility prevalences were seen among pneumococci isolated from children less than 15 years old, particularly those less than 2 years of age. This may be explained by the high consumption of antimicrobials among young children, compared to other age groups (4), and is in accordance with studies from other countries (18,21).…”

“…Nevertheless, reduced ceftriaxone susceptibility (the meningitis breakpoint) was detected in 3 to 4% of the isolates, which warrants careful continuous surveillance in the future. In countries with high PEN R prevalence, such as Taiwan, the United States, and Spain, 6 to 9% of the pneumococci are nonsusceptible to ceftriaxone (9,33,58), while in countries with low PEN R prevalences, such as Italy, Hungary, and Portugal, the respective proportion is below 1% (18,27,39). However, comparing the studies is sometimes difficult because of differences in the representativeness of the isolates and the breakpoints used.…”

“…Levofloxacin-resistant isolates were rare (Յ0.5%) in this study. According to several studies, the fluoroquinolone resistance prevalence is Յ3% in most countries (18,23,49), although studies, for example, from Canada and Portugal indicate the increasing prevalence of fluoroquinolone resistance (1,24).…”

Risk Factors for Multidrug-Resistant Invasive Pneumococcal Disease in South Africa, a Setting with High HIV Prevalence, in the Prevaccine Era from 2003 to 2008

“…The frequency of multidrug resistance in this study is much higher than those reported previously among large numbers of systematically collected invasive pneumococcal isolates from South Africa up to 1998 (16,22,33) but lower than levels observed in an international multicenter survey using both limited invasive and respiratory isolates from South Africa in 2004 (14). The significant increase in multidrug resistance observed over the 6-year period of our study is consistent with trends reported in other prevaccine era studies (10,22,55), suggesting that the problem of MDR IPD is worsening.…”

Perfiles de resistencia a fluoroquinolonas en aislamientos clínicos de cocos Gram positivos provenientes de hospitales colombianos, 1994-2004

“…La prevalencia mundial de resistencia en S. pneumoniae a las fluoroquinolonas es inferior al 2% (3,5,6,(30)(31)(32)(33)(34). Sin embargo, algunos estudios reportan mayores prevalencias, como el realizado en Canadá que informó un incremento en la resistencia a ciprofloxacino de más del 1% en 1997 a 4,2% en el 2005 y a levofloxacina de 0,2 a 1,1% en el mismo periodo (23).…”