Probabilistic chemotherapy in knee and hip replacement infection: the place of linezolid

Prosthetic joint infection (PJI) can occur with a wide range of microorganisms and clinical features. After replacement surgery of prosthetic joint, prescription of probabilistic broad-spectrum antimicrobial therapy is usual, while awaiting microbial culture results. The aim of our study was to describe the antibiotic susceptibility of microorganisms isolated from hip and knee PJI. The data were collected to determine the best alternative to the usual combination of piperacillin-tazobactam (TZP) or cefotaxime (CTX) and vancomycin (VAN). Based on a French prospective, multicenter study, we analyzed microbiological susceptibility to antibiotics of 183 strains isolated from patients with confirmed hip or knee PJI. In vitro susceptibility was evaluated: TZP+VAN, TZP+linezolid (LZD), CTX+VAN, and CTX+LZD. We also analyzed resistance to different antibiotics commonly used as oral alternatives. Among the 183 patients with PJI, 62 (34%) had a total knee prosthesis, and 121 (66%) a hip prosthesis. The main identified bacteria were Staphylococcus aureus (32.2% of isolates), coagulase-negative staphylococci (27.3%), Enterobacteriaceae (14.2%), and Streptococcus (13.7%). Infections were polymicrobial for 28 (15.3%) patients. All combinations were highly effective: CTX+VAN, CTX+LZD, TZP+VAN, and TZP+LZD (93.4%, 94%, 98.4%, and 98.9% of all cases respectively). Use of LZD instead of VAN in combination with a broad-spectrum beta-lactam covers almost all of the bacteria isolated in PJI. This association should be considered in probabilistic chemotherapy, as it is particularly easy to use (oral administration and no vancomycin monitoring)

DPO multiplex PCR as an alternative to culture and susceptibility testing to detect Helicobacter pylori and its resistance to clarithromycin

<p>Abstract</p> <p>Background</p> <p>Macrolide resistance in <it>Helicobacter pylori </it>is the major risk factor for treatment failure when using a proton pump inhibitor-clarithromycin containing therapy. Macrolide resistance is due to a few mutations on the 23S ribomosal subunit encoded by the 23S rRNA gene. The present study aimed at investigating the performance of the dual priming oligonucleotide (DPO)-PCR kit named Seeplex^®ClaR-<it>H. pylori </it>ACE detection designed to detect <it>H. pylori </it>and two types of point mutations causing clarithromycin resistance in <it>H. pylori</it>.</p> <p>Methods</p> <p>The performance of Seeplex^®ClaR-<it>H. pylori </it>ACE detection was evaluated on 127 gastric biopsies in comparison to conventional bacterial culture followed by the determination of susceptibility to clarithromycin by E-test, as well as by an in-house real-time PCR using a fluorescence resonance energy transfer (FRET) technology.</p> <p>Results</p> <p>Considering culture as the reference test, the sensitivity of DPO-PCR and real-time FRET-PCR was 97.7% and 100% while specificity was 83.1% and 80.7%, respectively. However, both PCR were concordant in detecting 14 <it>H. pylori </it>positive cases which were negative by culture. Globally, E-test and DPO-PCR were concordant with regard to clarithromycin susceptibility in 95.3% of the cases (41/43), while real-time FRET-PCR and DPO-PCR were concordant in 95% (57/60).</p> <p>Conclusion</p> <p>The DPO-PCR is an interesting tool to detect <it>H. pylori </it>on gastric biopsies and to study its susceptibility to clarithromycin in laboratories that cannot perform real-time PCR assays.</p

Multicentre prospective evaluation of histological and molecular criterion for diagnosis of prosthetic-joint infection

Objectives: This multicenter prospective study was performed to assess the contribution of broad range PCR diagnosis in prosthetic-joint infection (PJI). Methods: Adult patients treated for PJI at 7 centers were included between December 2010 and March 2012. Six per-operative samples were obtained for each patient, 5 for conventional cultures and 16S rRNA gene real-time PCR followed by sequencing, and 1 for histopathological classification according to Morawietz. Cultures and PCR were performed in a highly standardized manner, with 3 quality controls of PCR analyses. An infection was considered as proved (3 criteria: per-operative, bacteriological and histological), probable (clinical or bacteriological criterium), or excluded (no criterium). Molecular criterium for predicting PJI was determined using the bacteriological one as reference (&gt;=1 positive sample for virulent organism, and &gt;=3 positive samples for coagulase-negative staphylococci (CoNS) and P. acnes). Results: 299 patients were included, 264 with suspicion of sepsis (S) and 35 as controls (C). The 264 S presented with acute (19%), or chronic suspicion of PJI (81%). Infection was proved or probable in 212/264 S (80%), with the bacteriological criterium in 189/212 S (89%). Out of these, 156 (83%) had monomicrobial and 33 (17%) polymicrobial infections. The isolated pathogens were S. aureus (40%), CoNS (25%), streptococci (14%), Gram-Negative rods (10%), and anaerobes 8%. Histology results were not available for 55 patients, leaving 244 patients available for analysis. Histological findings of infection (Morawietz types II or III) were present in 128/169 (76%) proved or probable infections, in 3 patients without any other criterium, and were absent in excluded infections (n=42) and controls (n=29). PCR results were not analysable for 32 patients (S=28, C=4), leaving 267 patients (S=236, C=31) available for analysis. Molecular criterium of infection was present in 63/68 (93%) proved infections, 83/124 (67%) probable infections, 3/42 excluded infections, 0/2 histological criterium alone and 2/31 controls. Molecular criterium of infection was absent in 34/189 (18%) culture-positive S, and present in 8/23 culture-negative S (8 patients treated with antibiotics). Conclusions: According to this multicenter prospective study, 16S rRNA gene real-time PCR is less susceptible than culture for diagnosis of PJI. Molecular analysis could be recommended in culture-negative patients who were receiving antibiotics

Evaluation of 16S rRNA gene PCR sensitivity and specificity for diagnosis of prosthetic joint infection: a prospective multicenter cross-sectional study

There is no standard method for the diagnosis of prosthetic joint infection (PJI). The contribution of 16S rRNA gene PCR sequencing on a routine basis remains to be defined. We performed a prospective multicenter study to assess the contributions of 16S rRNA gene assays in PJI diagnosis. Over a 2-year period, all patients suspected to have PJIs and a few uninfected patients undergoing primary arthroplasty (control group) were included. Five perioperative samples per patient were collected for culture and 16S rRNA gene PCR sequencing and one for histological examination. Three multicenter quality control assays were performed with both DNA extracts and crushed samples. The diagnosis of PJI was based on clinical, bacteriological, and histological criteria, according to Infectious Diseases Society of America guidelines. A molecular diagnosis was modeled on the bacteriological criterion (≥ 1 positive sample for strict pathogens and ≥ 2 for commensal skin flora). Molecular data were analyzed according to the diagnosis of PJI. Between December 2010 and March 2012, 264 suspected cases of PJI and 35 control cases were included. PJI was confirmed in 215/264 suspected cases, 192 (89%) with a bacteriological criterion. The PJIs were monomicrobial (163 cases [85%]; staphylococci, n = 108; streptococci, n = 22; Gram-negative bacilli, n = 16; anaerobes, n = 13; others, n = 4) or polymicrobial (29 cases [15%]). The molecular diagnosis was positive in 151/215 confirmed cases of PJI (143 cases with bacteriological PJI documentation and 8 treated cases without bacteriological documentation) and in 2/49 cases without confirmed PJI (sensitivity, 73.3%; specificity, 95.5%). The 16S rRNA gene PCR assay showed a lack of sensitivity in the diagnosis of PJI on a multicenter routine basis

Assessment of the automated multiplex-PCR Unyvero i60 ITI cartridge system to diagnose prosthetic joint infection: a multicentre study

OBJECTIVES: Prosthetic joint infections (PJI) are responsible for significant morbidity and mortality and their number continues to rise. Their management remains complex, especially the microbiological diagnosis. Besides \u27homemade\u27 tests developed by several teams, new molecular biology methods are now available with different analytical performance and usability. METHODS: We studied the performances of one of these tests: ITI multiplex PCR (mPCR) by the Curetis company and compared it to either \u27optimized\u27 culture or 16S rRNA PCR. We performed a retrospective multicentre study to assess the contributions of mPCR in the diagnosis of PJI. We randomly selected 484 intraoperative specimens among 1252 of various types (biopsy, bone, tissue around the prosthesis, synovial fluid) from 251 patients in seven different hospitals. Each sample was treated according to the recommendations of the manufacturer. RESULTS: In all, 154 out of 164 (93.9%) samples negative in culture were negative with the mPCR. Among the 276 positive samples in culture, 251 (90.9%) were monomicrobial, of which 119 (47.4%) were positive with the mPCR, and 25 (9.1%) were polymicrobial, of which 12 (48%) were positive with the mPCR. The concordance rate of mPCR with culture was 58.1% (53.6%-62.7%) and the concordance rate with 16S rRNA PCR was 70.1% (65.5%-74.6%). CONCLUSION: This new standardized molecular test showed a lack of detection when the bacterial inoculum was low (number of positive media per sample and number of colonies per media) but can be useful when patients have received antibiotic therapy previously