Jean Cyr Yombi

Amplification-Based DNA Analysis in the Diagnosis of Prosthetic Joint Infection.

Microbiological cultures are moderately sensitive for diagnosing prosthetic joint infection (PJI). This study was conducted to determine whether amplification-based DNA methods applied on intraoperative samples could enhance PJI diagnosis compared with culture alone in routine surgical practice. Revision arthroplasty was performed for suspected PJI (n = 41) and osteoarthrosis control (n = 28) patients, and a diagnosis of PJI was confirmed in 34 patients. Amplification by polymerase chain reaction was performed on both 16S ribosomal DNA universal target genes and femA Staphylococcus-specific target genes. Species identification was achieved through amplicon sequencing. Amplification of the femA gene led to subsequent testing for methicillin resistance by amplification of the mecA gene. Microbiological and molecular assays identified a causative organism in 22 of 34 patients (64.7%) and in 31 of 34 patients (91.2%), respectively. In 18 of the 22 culture-positive patients, molecular and microbiological results were concordant for bacterial genus, species, and/or methicillin resistance. Bacterial agents were identified only by molecular methods in nine PJI patients, including seven who were receiving antibiotics at the time of surgery and one with recent but not concomitant antibiotherapy. DNA-based methods were found to effectively complement microbiological methods, without interfering with existing procedures for sample collection, for the identification of causative pathogens from intraoperative PJI samples, especially in patients with recent or concomitant antibiotherapy.

Antiretrovirals and the kidney in current clinical practice: Renal pharmacokinetics, alterations of renal function and renal toxicity

Assessment of renal function in HIV-positive patients is of increasing importance in the context of ageing and associated comorbidities. Exposure to nephrotoxic medications is widespread, and several commonly used antiretroviral drugs have nephrotoxic potential. Moreover, specific antiretrovirals inhibit renal tubular transporters resulting in the potential for drug–drug interactions as well as increases in serum creatinine concentrations, which affect estimates of glomerular filtration rate in the absence of changes in actual glomerular filtration rate. This review explores the effects of antiretroviral therapy on the kidney and offers an understanding of mechanisms that lead to apparent and real changes in renal function.

Influence of host genetic factors on efavirenz plasma and intracellular pharmacokinetics in HIV-1-infected patients

BACKGROUND Efavirenz (EFV) is characterized by interindividual pharmacokinetic variability causing inconsistent clinical responses. Previous studies have identified some possible genetic determinants of the variability in plasma concentrations. However, their impact on EFV intracellular pharmacokinetics remains mostly unexplored. AIMS To confirm previous observations concerning the influence of genetic polymorphisms on EFV plasma concentrations and to assess their effect on the intracellular pharmacokinetics of EFV. MATERIALS & METHODS EFV concentrations in plasma ([EFV](Cmin)) and in peripheral blood mononuclear cells ([EFV](CC)) were determined in 50 HIV-infected patients. Subjects were genotyped for 13 polymorphisms in 5 different genes (CYP2A6, CYP2B6, CYP3A5, UGT2B7 and ABCB1). Relationships between genetic status and [EFV](Cmin), [EFV](CC) or EFV accumulation in peripheral blood mononuclear cells (EFV accumulation ratio or accumulation ration [AR]) were then evaluated. RESULTS CYP2B6 allelic status was associated with differences in [EFV](Cmin) but also in [EFV](CC). Patients carrying at least one mutated allele showed significantly higher [EFV](Cmin) and [EFV](CC) than homozygous wild-type (mutated homozygous [m/m] >heterozygous [wt/m]>homozygous wild-type [wt/wt], p<0.001). ABCB1 rs3842T>C was significantly associated with higher EFV AR (p = 0.032). Finally, the ABCB1 3435C>T SNP was associated with a lower increase in CD4-cell count after EFV therapy initiation. CONCLUSION Our study corroborates previous findings indicating that knowledge of CYP2B6 genetic status should be taken into account for an EFV treatment. Our results also constitute the first demonstration of the significant influence of CYP2B6 genetic polymorphisms on [EFV](CC) and suggest that ABCB1 SNPs may also influence the clinical impact of EFV treatment.

Listeria infections associated with infliximab: case reports

Infliximab is a human-murine chimeric monoclonal antibody directed against tumor necrosis factor α (TNFα). Infliximab and other TNF blockers are used to treat inflammatory diseases such as rheumatoid arthritis (RA). TNF blockers are suspected to play a key role in some infections. We report here two cases of Listeria monocytogenes sepsis associated with infliximab treatment for RA. The first patient developed a terminal ileitis and a bacteraemia after three doses of infliximab; the second RA patient presented a bacteraemia associated with a prosthetic joint arthritis of the left hip, both related to Listeria. Those two cases occurred in a population of 518 patients treated with TNF blockers in our hospitals since the year 2000. Those events are of particular interest because of the severity of the infection, because the treatment differs from other infections, and because that, in the rheumatology unit, septic arthritis can mimic RA symptoms. They enhance the likelihood for this drug to increase the risk for infections with germs like Listeria.

Prevalence and epidemiology of HIV type 1 drug resistance among newly diagnosed therapy-naive patients in Belgium from 2003 to 2006.

This study is the first prospective study to assess the prevalence, epidemiology, and risk factors of HIV-1 drug resistance in newly diagnosed HIV-infected patients in Belgium. In January 2003 it was initiated as part of the pan-European SPREAD program, and continued thereafter for four inclusion rounds until December 2006. Epidemiological, clinical, and behavioral data were collected using a standardized questionnaire and genotypic resistance testing was done on a sample taken within 6 months of diagnosis. Two hundred and eighty-five patients were included. The overall prevalence of transmitted HIV-1 drug resistance in Belgium was 9.5% (27/285, 95% CI: 6.6-13.4). Being infected in Belgium, which largely coincided with harboring a subtype B virus, was found to be significantly associated with transmission of drug resistance. The relatively high rate of baseline resistance might jeopardize the success of first line treatment as more than 1 out of 10 (30/285, 10.5%) viruses did not score as fully susceptible to one of the recommended first-line regimens, i.e., zidovudine, lamivudine, and efavirenz. Our results support the implementation of genotypic resistance testing as a standard of care in all treatment-naive patients in Belgium.

Validation and clinical application of a high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of 10 anti-retrovirals in human peripheral blood mononuclear cells.

This paper reports the validation of a liquid chromatography tandem mass spectrometry (LC-MS/MS) method that allows the quantification of 10 antiretroviral (ARV) drugs in peripheral blood mononuclear cells (PBMCs) using 6 different isotopic internal standards (IS) and its clinical application. PBMCs are isolated from blood by density gradient centrifugation and drugs are extracted with a 60% methanol (MeOH) solution containing the 6 IS. The cell extract is then injected in the HPLC system and analytes are separated on a Symmetry Shield RP18 2.1 mm x 50 mm column. The different molecules are then detected by MS/MS in electrospray positive or negative ionisation modes and data are recorded using the multiple reaction monitoring (MRM) mode. Calibration curves are constructed in the range of 0.25-125 ng/ml of cell extract by a 1/x(2) weighted quadratic regression. The regression coefficients obtained are always greater than 0.99 and back calculated values always comprised in the range of +/-15% from their nominal concentration. Mean extraction recoveries are greater than 80% for all analytes and the method is accurate and precise with CV and bias lower than 9.4%. The lower limits of quantification (LLOQ) of the different drugs range from 0.0125 to 0.2 ng/ml of cell extract. This method was successfully applied to a cohort of 98 HIV-infected patients treated with Kaletra (400/100 mg of lopinavir/ritonavir (LPV/RTV) twice a day, n=48) or with Stocrin (600 mg once a day, n=50) and has been tested for cellular quantification of tipranavir (TPV) in 2 patients treated with Aptivus (500 mg twice a day). The patients treated by Kaletra showed mean cell-associated concentrations (CC) of 1819.0 and 917.2 ng/ml, for LPV and RTV, respectively. Patients treated with Stocrin showed mean CC of 2388.11 ng/ml while both patients under Aptivus showed TPV CC of 4322.7 and 1078.0 ng/ml, respectively. This method can be used to analyze ARV drug concentrations within the target tissue.

Disseminated Varicella Zoster Virus Infection in Adult Renal Transplant Recipients: Outcome and Risk Factors

BACKGROUND Disseminated varicella zoster virus (VZV) infection, whether due to primary infection or reactivation, may be life threatening in renal transplant recipients. The aims of this study were to assess the outcome of disseminated VZV infection in renal transplant recipients and to determine potential risk factors for mortality. METHODS A search of the English literature from 1985 to 2011 using PUBMED was performed. Reports involving renal transplant recipients younger than 16 years of age were excluded. RESULTS A total of 56 adult patients presenting with a disseminated cutaneous or visceral VZV infection was included. Seventy percent of cases occurred within 5 years after transplantation, and 89% within 10 years. Visceral complications including disseminated intravascular coagulation occurred in two thirds of patients. Mortality decreased significantly from 47% in the era before 1995 to 17% after 1995 (P = .04). Risk factors for mortality included visceral involvement, use of azathioprine as immunosuppressant, and longer time between transplantation and VZV infection. VZV seropositivity did not influence fatal outcome. CONCLUSION Disseminated VZV infection can be life threatening in renal transplant recipients with a global mortality rate of 30%. This rate seems to have decreased since 1995. Seropositive VZV patients with disseminated infection are not protected from fatal outcome.

Association between ABCC2 polymorphism and lopinavir accumulation in peripheral blood mononuclear cells of HIV-infected patients

AIM Lopinavir (LPV) is a potent protease inhibitor used in combination with low doses of ritonavir in the treatment of HIV-infected patients. LPV pharmacokinetics is characterized by a large interindividual variability requiring the use of therapeutic drug monitoring in different clinical situations. While the sources of this variability are still unknown, several genetic polymorphisms in biotransformation enzymes or transporter proteins involved in the metabolism and/or the distribution of LPV appear as good candidates. Therefore, the aim of the present study was to investigate the influence of selected genetic polymorphisms on LPV trough plasma concentrations ([LPV](Cmin)), LPV concentrations in peripheral blood mononuclear cells ([LPV](CC)) and the LPV accumulation ratio ([LPV](CC):[LPV](Cmin)). MATERIALS & METHODS A total of 53 patients receiving Kaletra((R)) (Abbott Laboratories, IL, USA) (LPV+ritonavir) were genotyped for 14 different polymorphisms in biotransformation enzymes and transporter proteins. [LPV](Cmin), [LPV](CC) and [LPV](CC):[LPV](Cmin) were compared according to the patients genotypes. RESULTS & CONCLUSION The 4544G>A (rs8187710)polymorphism in ABCC2 was associated with a higher accumulation of LPV in peripheral blood mononuclear cells of HIV-treated patients. As already observed in previous studies, ABCB1 or CYP3A5 polymorphisms had no impact on [LPV](Cmin) and we did not detect any influence of these polymorphisms on [LPV](CC) and its accumulation in mononuclear cells. In conclusion, this pilot study suggests, for the first time, that the 4544G>A polymorphism in ABCC2 could explain a significant part of the interindividual variability in LPV pharmacokinetics. Further investigations are needed to confirm this association and to explore its real pharmacodynamic impact.

Streptococcus gordonii septic arthritis: two cases and review of literature.

BackgroundDespite advances in antimicrobial and surgical therapy, septic arthritis remains a rheumatologic emergency that can lead to rapid joint destruction and irreversible loss of function. In adults, Staphylococcus aureus is the most common microorganism isolated from native joints. Streptococcus gordonii is a prominent member of the viridans group of oral bacteria and is among the bacteria most frequently identified as being primary agent of subacute bacterial endocarditis. To the best of our knowledge, Streptococcus gordonii has not yet been described as agent of septic arthritis.Case PresentationWe describe here two cases of septic arthritis due to Streptococcus gordonii. It gives us an opportunity to review epidemiology, diagnosis criteria and management of septic arthritis.ConclusionAlthough implication of S. gordonii as aetiologic agent of subacute endocarditis is well known, this organism is a rare cause of septic arthritis. In this case, the exclusion of associated endocarditis is warranted.

HIV-1 proviral resistance mutations: usefulness in clinical practice.

Transmitted HIV strains may harbour drug resistance mutations. HIV‐1 drug resistance mutations are currently detected in plasma viral RNA. HIV‐1 proviral DNA could be an alternative marker, as it persists in infected cells.