Comparative Molecular and Microbiologic Diagnosis of Bacterial Endocarditis

Sequencing of 16S rDNA, and of sodAint and rpoBint in some cases, was applied to DNA from heart valves of 46 patients (36 with definite and 10 with possible endocarditis). Sequence-based identifications were compared with those obtained with conventional methods. Among the 36 definite cases, 30 had positive blood cultures and 6 had negative cultures. Among the 30 positive cases, sequencing of 16S rDNA permitted identification of species (18), genus (8), or neither (4); sodAint and rpoBint sequencing was necessary for species identification in 8 cases. Species identifications were identical in only 61.5%, when conventional techniques and DNA sequencing were used. In five of the six blood culture–negative endocarditis cases, sequencing identified Bartonella quintana (3), B. henselae (1), and Streptococcus gallolyticus (1). Our results demonstrate a clear benefit of molecular identification, particularly in cases of blood culture–negative endocarditis and of possible endocarditis, to confirm or invalidate the diagnosis. Moreover, in 19.4% of the definite cases, the improvement in species identification by sequencing led to improved patient management

Fluoroquinolone Resistance Associated with Target Mutations and Active Efflux in Oropharyngeal Colonizing Isolates of Viridans Group Streptococci

Oropharyngeal samples from 60 hospitalized patients (30 fluoroquinolone [FQ]-treated and 30 non-FQ-treated patients) and 30 untreated nonhospitalized healthy control subjects yielded 20 isolates of viridans group streptococci with reduced susceptibility to FQ, mostly from the hospitalized patients. An efflux phenotype was commonly encountered, expressed either alone or with topoisomerase mutations. Interspecies transfer of the efflux phenotype was demonstrated via transformation of Streptococcus pneumoniae R6 with DNA from S. mitis and S. oralis

Case of Indolent Endocarditis Due to Pseudomonas stutzeri with Genetic Evidence of Relapse after 4 Years▿

Pseudomonas stutzeri, a gram-negative bacterium, is a common inhabitant of soil and water. We report an unusual case of a relapse of infective endocarditis due to P. stutzeri 4 years after the initial episode. The identity of the strains was proven by genomic analysis

Hip Prosthesis Infection Due to Mycobacterium wolinskyi

Mycobacterium wolinskyi, first described in 1999, is a rapidly growing mycobacterium related to the Mycobacterium smegmatis group. Only eight cases of infection due to this microorganism have been reported, including three cases of bone infection. Here, we present the first case of a joint prosthesis infection cured with the combination of surgery and prolonged antibiotic therapy. The microorganism was identified by biochemical tests and 16S rRNA and Hsp65 gene sequence analysis

Molecular Diagnosis of Kingella kingae Pericarditis by Amplification and Sequencing of the 16S rRNA Gene▿

Kingella kingae is a fastidious gram-negative bacillus that is considered an emerging pathogen in pediatric settings but remains less common in adults. Here we describe a case of pericarditis in an immunocompetent adult host. The microorganism was identified directly from the clinical sample by molecular techniques, i.e., 16S rRNA gene amplification and sequencing

Postoperative Mediastinitis Due to Finegoldia magna with Negative Blood Cultures▿

We report a case of Finegoldia magna (formerly known as Peptostreptococcus magnus) mediastinitis following coronary artery bypass in a 50-year-old patient. Even if staphylococci remain the main causative organism of postoperative mediastinitis, the responsibility of anaerobic bacteria must be considered in cases of fever and sternal drainage with negative blood cultures

Dolosigranulum pigrum Causing Nosocomial Pneumonia and Septicemia▿

We report a case of non-ventilator-associated nosocomial pneumonia and septicemia due to Dolosigranulum pigrum, a rare gram-positive opportunistic pathogen. The organism was isolated from bronchoalveolar lavage fluid and blood of a debilitated patient. D. pigrum was identified after 16S rRNA gene sequencing

Outbreak of Methicillin-Resistant Staphylococcus aureus with Reduced Susceptibility to Glycopeptides in a Parisian Hospital

Epidemiological relationships were investigated between 40 methicillin-resistant Staphylococcus aureus (MRSA) strains with decreased glycopeptide susceptibility isolated from November 1998 to March 1999 from 39 patients (17 infected and 22 colonized patients) in nine wards of the Broussais Hospital, Paris, France. Reduced glycopeptide susceptibility was readily detected on brain heart infusion (BHI) agar containing 6 μg of teicoplanin per ml and on gradient plates, but not by the standard disk diffusion method. The MICs of vancomycin and teicoplanin, determined on BHI agar, were 4 and 8 to 32 μg/ml, respectively (standard antibiotic dilution), and 4 to 8 and 8 to 32 μg/ml, respectively (E-test). All strains were resistant to macrolides, aminoglycosides, tetracycline, rifampin, sulfonamides, and pefloxacin, showed reduced susceptibility to fusidic acid and fosfomycin, and were susceptible to trimethoprim and chloramphenicol. Pulsed-field gel electrophoresis and lysotyping revealed that a multidrug-resistant MRSA clone with decreased susceptibility to glycopeptides has been discretely endemic since at least 1996 in our institution, where it was responsible for an outbreak in November and December 1998