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The ability to form biofilms is a recognized trait of Stenotrophomonas maltophilia, but the extent of its clinical relevance is still unclear. The present multicenter prospective study (ANSELM) aims at investigating the association between biofilm formation and clinical outcomes of S. maltophilia infections. One hundred and nine isolates were collected from various geographical origins and stratified according to their clinical relevance. Biofilm formation was evaluated by the microtiter plate assay and correlated with microbiological and clinical data from the associated strains. Antibiotic susceptibility of the planktonic cells was tested by the disk diffusion technique, while antibiotic activity against mature biofilms was spectrophotometrically assessed. Most strains (91.7%) were able to form biofilm, although bloodborne strains produced biofilm amounts significantly higher than strains causing hospital- rather than community-acquired infections, and those recognized as "definite" pathogens. Biofilm formation efficiency was positively correlated with mechanical ventilation (p = 0.032), whereas a negative relationship was found with antibiotic resistance (r2 = 0.107; p < 0.001), specifically in the case of the pathogenic strains. Mature S. maltophilia biofilms were markedly more resistant (up to 128 times) to cotrimoxazole and levofloxacin compared with their planktonic counterparts, especially in the case of bloodborne strains. Our findings indicate that biofilm formation by S. maltophilia is obviously a contributing factor in the pathogenesis of infections, especially in deep ones, thus warranting additional studies with larger cohort of patients and isolates. [ABSTRACT FROM AUTHOR]

Introduction: The introduction of pneumococcal conjugate vaccine (PCV-7) has modified the epidemiology of invasive pneumococcal disease (IPD). Our aim was to investigate the epidemiological features of IPD before and after implementing the use of PCV-7., Methods: All invasive Streptococcus pneumoniae strains isolated in our hospital from 2000 to 2006 were included. Serotypes were identified and antibiograms were performed in all cases. Data obtained before (2000-2001) and after (2004-2006) authorization of PCV-7 use in Spain were compared., Results: There were 241 cases of IPD. None of the patients with IPD aged 2 years or younger had received PCV-7. PCV-7 coverage in children aged 5 or younger was about 48%. There was a non-significant increase in the incidence of IPD in children (from 53.8 to 57.8 cases/100 000 population), with no change in adults. When IPD incidence was adjusted by the number of blood samples collected, there was a non-significant decrease in both children and adults. Since PCV-7 came on the market, there has been a decrease in vaccine serotypes and an increase in non-vaccine serotypes. The emergent serotypes since that time include 3, 6A, 15, and 19A. Penicillin resistance decreased significantly (p<0.001) from the pre-vaccine period (87.3%) to 2003 (13.8%), and later rose from 2003 through 2006 (41.7%). Erythromycin resistance showed no changes during the study., Conclusions: The incidence of IPD in children aged 2 years and younger in Gran Canaria has not decreased despite the introduction of PCV-7. However, there has been a reduction in the number of cases related to vaccine serotypes and a significant decrease in penicillin resistance. In contrast, non-vaccine serotype IPD cases have increased. Universal vaccination and the use of new polyvalent vaccines may enhance these effects.

Background: Macrolide resistance in Streptococcus pneumoniae is coded by the ermB and mefA/E genes. The aim of this study was to determine the status of macrolide-resistance, the molecular mechanisms involved, the serogroup relationships, and the level of co-resistance in S. pneumoniae isolates from Gran Canaria and Lanzarote, in the Canary Islands, Spain., Methods: Macrolide resistance phenotypes were investigated in 261 S. pneumoniae clinical isolates over a two-year period (2004 and 2005). Genotypes were determined by PCR (detection of ermB and mefA/E genes)., Results: Overall macrolide resistance was 40.6% (106 isolates); 79.2% (84) of resistant isolates presented the MLSB phenotype (98.8% harbored the ermB gene), with a predominance of serogroup 19, and 20.8% (22) presented the M phenotype (77.3% displayed the mefA/E gene), all associated with serogroup 14. Worthy of note, the M phenotype was found in 8 invasive isolates from Lanzarote (80%) all from serogroup 14. The ermB and mefA/E genes were detected in 7 isolates belonging to serogroup 19. Absence of co-resistance was observed most frequently in serogroup 14 (66.7%). Co-resistance with penicillin G, tetracycline, and trimethoprim-sulfamethoxazole was associated with serogroup 19 (36.8%). Two isolates (0.8%) were resistant to telithromycin., Conclusion: The frequency of macrolide resistance mechanisms in the Canary Islands is different from that observed in the rest of Spain, particularly in Lanzarote, where 80% of isolates harbored the mefA/E gene and belonged to serogroup 14.