Caroline Loïez

Outcome and predictors of treatment failure in total hip/knee prosthetic joint infections due to Staphylococcus aureus.

The results of the present study suggest that ASA score ≤ 2 and use of rifampin-combination therapy are two independent factors associated with favorable outcome of patients treated for total hip or knee prosthetic infections due to S. aureus.

Detection of Yersinia pestis in Sputum by Real-Time PCR

ABSTRACT A 5′ nuclease PCR assay for detection of the Yersinia pestis plasminogen activator (pla) gene in human respiratory specimens with simulated Y. pestis infection was developed. An internal positive control was added to the reaction mixture in order to detect the presence of PCR inhibitors that are often found in biological samples. The assay was 100% specific for Y. pestis. In the absence of inhibitors, a sensitivity of 102 CFU/ml of respiratory fluid was obtained. When inhibitors were present, detection of Y. pestis DNA required a longer sample treatment time and an initial concentration of bacteria of at least 104 CFU/ml. The tests total turnaround time was less than 5 h. The assay described here is well suited to the rapid diagnosis of pneumonic plague, the form of plague most likely to result from a bioterrorist attack.

Cost-Effectiveness of Switch to Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Routine Bacterial Identification

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) allows instant identification of microorganisms by analyzing their total protein content ([1][1]-[3][2]). In September 2009, we switched from conventional biochemical techniques (mainly Vitek 2 and API strips

Tolerability of prolonged linezolid therapy in bone and joint infection: protective effect of rifampicin on the occurrence of anaemia?

BACKGROUND Linezolid therapy has shown high rates of clinical success in patients with osteomyelitis and prosthetic joint infections caused by Gram-positive cocci. Recent studies have demonstrated that linezolid/rifampicin combination therapy prevents the emergence of rifampicin-resistant mutations in vitro. However, linezolid/rifampicin combination-related haematological and neurological toxicities have not been evaluated. OBJECTIVES To assess the tolerability of prolonged linezolid/rifampicin combination therapy compared with other linezolid-containing regimens in patients with bone and joint infections. METHODS We reviewed the medical records of 94 patients who had received linezolid for >4 weeks after bone and joint infections. Anaemia was defined as a ≥2 g/dL reduction in haemoglobin, leucopenia as a total leucocyte count <4 × 10(9)/L, and thrombocytopenia as a reduction in platelet count to <75% of baseline. RESULTS Anaemia was less frequent among patients on linezolid/rifampicin combination therapy than among patients on linezolid alone or in combination with other drugs (9.3%, 44% and 52%, respectively; P<0.01). In multivariate analysis, age and treatment group were independently associated with anaemia. Thrombocytopenia was reported in 44% of patients on linezolid/rifampicin combination therapy, in 48% of patients on linezolid alone and in 57.7% of patients on other linezolid-containing regimens. Age was the only variable associated with thrombocytopenia (P=0.019) in univariate analysis. CONCLUSIONS Linezolid/rifampicin combination therapy was associated with a significantly reduced incidence of anaemia among patients with bone and joint infections, but it did not have an effect on thrombocytopenia and peripheral neuropathy rates. Linezolid/rifampicin combination therapy was not associated with poor clinical outcomes.

Performances of VITEK 2 Colorimetric Cards for Identification of Gram-Positive and Gram-Negative Bacteria

ABSTRACT The purpose of this study was to evaluate the new VITEK 2 identification cards that use colorimetric reading to identify gram-positive and gram-negative bacteria (GP and GN cards, respectively) in comparison to fluorimetric cards (ID-GPC and ID-GNB, respectively). A total of 580 clinical isolates and stock collection strains belonging to 116 taxa were included in the study. Of the 249 gram-positive strains tested with both the ID-GPC and GP cards, 218 (87.5%) and 235 (94.4%) strains were correctly identified (to the genus and species level), respectively. Of the 331 gram-negative strains tested with the ID-GNB and GN cards, 295 (89.1%) and 321 (97%) strains were correctly identified, respectively. Another focus of the study was to apply the percentages of correct identifications obtained in this study to the list of bacteria isolated in our laboratory (32,739 isolates) in the year 2004. We obtained 97.9% correct identifications with the colorimetric cards and 93.9% with fluorescent cards.

First Case of Osteomyelitis Caused by “Staphylococcus pettenkoferi”

ABSTRACT “Staphylococcus pettenkoferi” (proposed name) was identified as an unusual agent of osteomyelitis in a diabetic foot infection. The phenotypical tests used failed to give a good identification. Molecular 16S rRNA gene and rpoB sequencing allowed us to correctly identify this new species of coagulase-negative staphylococcus responsible for this chronic infection.

Paracoccus yeei: a new unusual opportunistic bacterium in ambulatory peritoneal dialysis.

Paracoccus yeei was identified as the etiologic agent of peritonitis in an ambulatory peritoneal dialysis patient. While the old biochemical identification kits are not able to identify this species, the new colorimetric VITEK 2 GN card correctly identified this isolate in 7hours. Its identity was confirmed by sequencing of the 16S rRNA gene.

Molecular diagnosis of arthritis due to streptobacillus moniliformis.

Streptobacillus moniliformis was identified as etiologic agent of arthritis utilizing a 16S rDNA molecular kit in our clinical laboratory. With the increasing of human contacts with rat as pet, this method would appear suitable to identify fastidious Gram-negative rod involved in arthritis specially when the clinical context is not evocative.

Usefulness of Real-Time PCR for the Diagnosis of Sepsis in ICU-Acquired Infections

Real-time PCR methods are able to rapidly detect a wide panel of microorganisms. These methods are of interest in critically ill patients to determine the presence of bacteria in the blood and other biological samples, especially in those patients with prior antimicrobial treatment. In intensive care unit (ICU), the LightCycler SeptiFast (LC-SF) Test provides 1.5 to 2 fold higher positivity rate compared with conventional blood cultures. Although identification of the bacterium by LC-SF is rapid and sensitive, susceptibility test could not be performed using this technique, except the methicillin- resistance for Staphylococci. The conventional cultures remain necessary for samples in ICU because of the high incidence of multidrug-resistant bacteria and the need for antimicrobial susceptibility of the bacterium to treat the patient correctly. A negative result for a Gram positive or negative bacterium allows deescalating the initial antimicrobial treatment, and decreasing the pressure of selection. Moreover, it is necessary to understand and interpret a DNA signal knowing that a dead bacterial material may be detected in a patient without any infection. What is the clinical relevance of bacterial DNA present in the blood and does the DNAemia found reflect true infection? Cost-effectiveness of the real-time PCR should be determined. Meanwhile, this test should be restricted to severe clinical situations, especially ICU patients with severe sepsis. In the future, real-time PCR tests should include more pathogens and antimicrobial resistant targets.

An unusual case of prosthetic joint infection due to Arcanobacterium bernardiae

A 78-year-old man was admitted to the orthopaedic ward of the Centre Hospitalier Régional Universitaire for a haematoma of the left thigh which had appeared after a fall and 3 weeks of insidious pain. Medical history included a left total hip prosthesis because of a work accident 27 years previously. Examination revealed that his left hip prosthesis had worked loose, which was probably responsible for the fall. Laboratory data included a blood leukocyte count of 9.3610 l, with 73 % polymorphonuclear leukocytes, and a Creactive protein level of 18 mg l. The haematoma was drained surgically and the prosthesis was removed and replaced by a spacer. During the intervention, four biopsies (haematoma, muscle, femur and acetabulum) were performed. Gram stain of the haematoma and the femur biopsy smears showed Gram-positive bacilli. As the patient was apyretic, blood cultures were not performed. A combination of linezolid and cefotaxime was started until the microbiological results were available.