Identification and detection of Mitis group streptococci, which contains Streptococcus pneumoniae, has been hampered by the lack of sensitive and specific assays. In this study we evaluated several... Show moreIdentification and detection of Mitis group streptococci, which contains Streptococcus pneumoniae, has been hampered by the lack of sensitive and specific assays. In this study we evaluated several biochemical and molecular assays for identification of S. pneumoniae and S. pseudopneumoniae and their distinction from other Mitis group streptococci using a collection of 54 isolates obtained by routine culture of 53 respiratory specimens from patients with community-acquired pneumonia. The combined results of the biochemical and molecular assays indicated the presence of 23 S. pneumoniae, two S. pseudopneumoniae and 29 other Mitis group streptococci isolates. The tube bile solubility test that is considered as gold standard for identification of S. pneumoniae showed concordant results with optochin susceptibility testing (CO(2) atmosphere) and a real-time multiplex PCR assay targeting the Spn9802 fragment and autolysin gene. Optochin susceptibility testing upon incubation in O(2) atmosphere, bile solubility testing by oxgall disk, matrix-assisted laser desorption ionization-time of flight mass spectrometry and sequence analysis of the tuf and rpoB genes resulted in several false positive, false negative or inconclusive results. The S. pseudopneumoniae isolates could only be identified by molecular assays and the multiplex real-time PCR assay was concluded to be most convenient for identification of S. pneumoniae and S. pseudopneumoniae. Using this method S. pneumoniae and S. pseudopneumoniae DNA could be detected in the respiratory samples from which they were isolated and in an additional 11 samples from which only other streptococci were isolated. Show less
Background Previously, we assessed selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) on survival and prevention of bacteraemia in patients in... Show moreBackground Previously, we assessed selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) on survival and prevention of bacteraemia in patients in intensive-care units. In this analysis, we aimed to assess effectiveness of these interventions for prevention of respiratory tract colonisation and bacteraemia with highly resistant microorganisms acquired in intensive-care units. Methods We did an open-label, clustered group-randomised, crossover study in 13 intensive-care units in the Netherlands between May, 2004, and July, 2006. Participants admitted to intensive-care units with an expected duration of mechanical ventilation of more than 48 h or an expected stay of more than 72 h received SOD (topical tobramycin, colistin, and amphotericin B in the oropharynx), SDD (SOD antibiotics in the oropharynx and stomach plus 4 days' intravenous cefotaxime), or standard care. The computer-randomised order of study regimens was applied by an independent clinical pharmacist who was masked to intensive-care-unit identity. We calculated crude odds ratios (95% Cl) for rates of bacteraemia or respiratory tract colonisation with highly resistant microorganisms in patients who stayed in intensive-care units for more than 3 days (ie, acquired infection). This trial is registered at http://isrctn.org, number ISRCTN35176830. Findings Data were available for 5927 (>99%) of 5939 patients, of whom 5463 (92%) were in intensive-care units for more than 3 days. 239 (13%) of 1837 patients in standard care acquired bacteraemia after 3 days, compared with 158 (9%) of 1758 in SOD (odds ratio 0.66,95% CI 0.53-0.82), and 124 (7%) of 1868 in SDD (0.48,0.38-0-60). Eight patients acquired bacteraemia with highly resistant microorganisms during SDD, compared with 18 patients (with 19 episodes) during standard care (0.41,0-18-0-94; rate reduction [RR] 59%, absolute risk reduction [ARR] 0.6%) and 20 during SOD (0.37,0.16-0-85; RR 63%, ARR 0.7%). Of the patients staying in intensive-care units for more than 3 days, we obtained endotracheal aspirate cultures for 881 (49%) patients receiving standard care, 886 (50%) receiving SOD, and 828 (44%) receiving SDD. 128 (15%) patients acquired respiratory tract colonisation with highly resistant microorganisms during standard care, compared with 74 (8%) during SDD (0.58, 0.43-0.78; RR 38%, ARR 5.5%) and 88 (10%) during SOD (0.65, 0.49-0.87; RR 32%, ARR 4.6%). Acquired respiratory tract colonisation with Gram-negative bacteria or cefotaxime-resistant and colistin-resistant pathogens was lowest during SDD. Interpretation Widespread use of SDD and SOD in intensive-care units with low levels of antibiotic resistance is justified. Show less
