Linezolid resistance has dominantly been mediated by mutations in 23S rRNA or ribosomal protein L4 genes. Recently, cfr has demonstrated the ability to produce a phenotype of resistance to not only oxazolidinones, but also other antimicrobial classes (phenicols, lincosamides, pleuromutilins, and streptogramin A). We describe the first detection of cfr-mediated linezolid resistance in Staphylococcus aureus and Staphylococcus epidermidis recovered from human infection cases monitored during the 2007 LEADER Program.

Two strains of Raoultella planticola and one of Raoultella ornithinolytica showing carbapenem resistance were recovered from patients hospitalized in New Jersey and Ohio. All patients had received previous antimicrobial treatment, including carbapenems. These strains harbored bla KPC-2 and bla KPC-3 . Carbapenemase genes were embedded in isoforms of Tn4401 and were plasmidic and chromosomal in location.Raoultella species are gram-negative aerobic bacilli belonging to the Enterobacteriaceae family that are closely related to Klebsiella spp. (7). These environmental organisms, infrequently causing human infections, appear to have pathogenicity similar to that of Klebsiella pneumoniae (8). The first human Raoultella spp. invasive infection was described in 1984, and bloodstream infections have been reported, though rarely (1). Studies have shown that 0.2 to 19.0% of isolates initially identified as Klebsiella spp. were Raoultella spp. by 16S rRNA analysis and that the prevalence of these organisms in clinical settings can vary geographically (8).(This work was presented at the 19th European Conference of Clinical Microbiology and Infectious Diseases, Helsinki, Finland, 2009.) A total of 7,248 Enterobacteriaceae isolates collected in medical centers from North America, Latin America, and Europe during 2008 were susceptibility tested by the reference broth microdilution method and interpretation criteria (3, 4). Isolates displaying imipenem and/or meropenem MICs of Ն2 g/ml were tested with the modified Hodge test (MHT) using imipenem and meropenem disks (4) and multiplex PCRs for the detection of carbapenemase-encoding genes, including bla IMP , bla VIM , bla KPC, bla SME , and bla GES variants and bla IMI , bla NMC-A , and bla .Among 134 (1.8% overall) isolates that were nonsusceptible to carbapenems, three (2.2%) Raoultella isolates from bloodstream infections were observed. MHT was positive for all three strains, and PCRs were positive for bla KPC . Sequencing of 16S rRNA revealed that two isolates were R. planticola (from Ohio and New Jersey) and one was R. ornithinolytica (from New Jersey). The isolates from New Jersey were detected in the same hospital and harbored bla , whereas the strain from Ohio carried bla KPC-2 . The clinical histories of the patients presenting infections with KPC-producing Raoultella spp. are summarized below. Case 1. An 83-year-old female patient was admitted to a hospital (Ohio) with a diagnosis of community-acquired bacterial pneumonia in May 2008. Sputum, paracentesis, and blood cultures were negative. Urine culture grew Escherichia coli, and the patient received courses of moxifloxacin, ceftriaxone, azithromycin, and meropenem. The patient was discharged and returned after 3 weeks with respiratory complaints. A tracheal-aspirate specimen grew a multidrug-resistant A. baumannii strain, and blood culture grew an enteric-like gram-negative bacillus (R. planticola). The patient subsequently died.Case 2. The patient was a 64-year-old man admitted to a hospital (New Jersey) in Septe...

BackgroundHost factors and complications have been associated with higher mortality in infective endocarditis (IE). We sought to develop and validate a model of clinical characteristics to predict 6‐month mortality in IE.Methods and ResultsUsing a large multinational prospective registry of definite IE (International Collaboration on Endocarditis [ICE]–Prospective Cohort Study [PCS], 2000–2006, n=4049), a model to predict 6‐month survival was developed by Cox proportional hazards modeling with inverse probability weighting for surgery treatment and was internally validated by the bootstrapping method. This model was externally validated in an independent prospective registry (ICE‐PLUS, 2008–2012, n=1197). The 6‐month mortality was 971 of 4049 (24.0%) in the ICE‐PCS cohort and 342 of 1197 (28.6%) in the ICE‐PLUS cohort. Surgery during the index hospitalization was performed in 48.1% and 54.0% of the cohorts, respectively. In the derivation model, variables related to host factors (age, dialysis), IE characteristics (prosthetic or nosocomial IE, causative organism, left‐sided valve vegetation), and IE complications (severe heart failure, stroke, paravalvular complication, and persistent bacteremia) were independently associated with 6‐month mortality, and surgery was associated with a lower risk of mortality (Harrell's C statistic 0.715). In the validation model, these variables had similar hazard ratios (Harrell's C statistic 0.682), with a similar, independent benefit of surgery (hazard ratio 0.74, 95% CI 0.62–0.89). A simplified risk model was developed by weight adjustment of these variables.ConclusionsSix‐month mortality after IE is ≈25% and is predicted by host factors, IE characteristics, and IE complications. Surgery during the index hospitalization is associated with lower mortality but is performed less frequently in the highest risk patients. A simplified risk model may be used to identify specific risk subgroups in IE.

We studied three clinical isolates of Candida spp. (one C. tropicalis isolate and two C. glabrata isolates) from patients with invasive candidiasis. The first isolate emerged during echinocandin treatment, while the others emerged after the same treatment. These strains harbored an amino acid substitution in Fksp never linked before with reduced echinocandin susceptibility in C. tropicalis or in C. glabrata. The molecular mechanism of reduced susceptibility was confirmed using a 1,3-␤-D-glucan synthase inhibition assay.

In this prospective, multinational cohort of patients with S. aureus PVIE, EVS was not associated with reduced 1-year mortality. The decision to pursue EVS should be individualized for each patient, based upon infection-specific characteristics rather than solely upon the microbiology of the infection causing PVIE.