Diagnosis Of Persistent Infection Research Articles

Development and application of a simple recombinase polymerase amplification assay for rapid point-of-care detection of feline herpesvirus type 1

Feline herpesvirus type 1 (FHV-1) is a highly contagious pathogen of domestic cats and other members of the family Felidae. Point-of-care diagnosis of persistent infection in cats is essential for control of its spread. A recombinase polymerase amplification (RPA) assay (RPA-LFD-FHV) combined with a lateral flow dipstrip (LFD) was developed that uses human body heat for incubation. Sensitivity was evaluated by testing a serial dilution of a control plasmid, and specificity was evaluated by testing related viruses. Swab samples from cats with suspected infection were tested by RPA-LFD-FHV, and the results were compared to those obtained by PCR to evaluate its clinical performance. The RPA-FLD-FHV assay was carried out successfully within 20 min, using body heat for incubation. The RPA-FLD-FHV had a detection limit of 103 copies of the FHV-1 gD gene, which was lower than that of PCR, which was 104 copies. The assay could detect templates of FHV-1 but not those of other feline and canine viruses. Viruses in boiled samples could be efficiently detected by the RPA-FLD-FHV. Thirty-one out of the 80 samples were positive by the RPA-FLD-FHV assay, whereas only 27 were positive by PCR. DNA sequencing confirmed that the four samples that were positive by RPA-FLD-FHV but negative by PCR were indeed positive. These results indicate that RPA-FLD-FHV is applicable for clinical use. The RPA-FLD-FHV assay is a simple, rapid, and reliable method for point-of-care diagnosis of FHV-1 infection.

Diagnosis of Persistent Infection in Prosthetic Two-Stage Exchange: Evaluation of the Effect of Sonication on Antibiotic Release from Bone Cement Spacers.

Introduction: When treating periprosthetic joint infection with a two-stage procedure, antibiotic-impregnated spacers can be used in the interval between prosthetic removal and reimplantation. In our experience, cultures of sonicated spacers are most often negative. The objective of the study was to assess whether that sonication causes an elution of antibiotics, leading to elevated antibiotic concentrations in the sonication fluid inhibiting bacterial growth and thus causing false-negative cultures.Methods: A prospective monocentric study was performed from September 2014 to March 2016. Inclusion criteria were a two-stage procedure for prosthetic infection and agreement of the patient to participate in the study. Spacers were made of gentamicin-containing cement to which tobramycin and vancomycin were added. Antibiotic concentrations in the sonication fluid were determined by mass-spectometry (LC-MS).Results: 30 patients were identified (15 hip and 14 knee and 1 ankle arthroplasties). No cases of culture positive sonicated spacer fluid were observed in our serie. In the sonication fluid median concentrations of 13.2µg/ml, 392 µg/ml and 16.6 µg/ml were detected for vancomycin, tobramycin and gentamicin, respectively. According to the European Committee on antimicrobial susceptibility testing (EUCAST), these concentrations released from cement spacer during sonication are higher than the minimal inhibitory concentrations (MICs) for most bacteria relevant in prosthetic joint infections.Conclusion:Spacer sonication cultures remained sterile in all of our cases. Elevated concentrations of antibiotics released during sonication could explain partly negative-cultured sonicated spacers. Indeed, the absence of antibiotic free interval during the two-stages can also contribute to false-negative spacers sonicated cultures.

Diagnostic Utility of Histological Analysis for Detecting Ongoing Infection During Two-Stage Revision Arthroplasty in Patients With Inflammatory Arthritis

BackgroundSurgeons often rely on intra-operative histology (frozen sections [FS]) to determine the next step in surgical management during the second stage (re-implantation surgery) of 2-stage revision arthroplasty. The purpose of the study is to assess the accuracy of permanent sections (PS) and FS in the diagnosis of persistent infection during re-implantation in patients with an inflammatory arthritis. MethodsFrom 2001 to 2016, 47 planned second-stage revision total hip arthroplasty and total knee arthroplasty in patients with inflammatory arthritis were identified. Revisions were classified as having persistent infection if they were Musculoskeletal Infection Society positive at the time of second stage. PS or FS was considered to be positive for infection when at least one of the specimens demonstrated an acute inflammation. Receiver operating characteristic analysis was performed to obtain the diagnostic parameters. ResultsThere were 9 (19%) persistent infections. Both PS and FS had very high specificity (PS = FS = 94.7%). Sensitivity of PS was higher than FS, although not statistically significant (PS = 88.9%, FS = 55.6%, P = .083). Overall, PS had a better diagnostic utility than FS (area under the curve: PS vs FS = 0.92 vs 0.75, P = .045). Four specimens had discrepancies between PS and FS histology. In all 4 instances, the specimens were read as positive (infected) by PS, but negative by FS. ConclusionHistological analysis is recommended at the time of re-implantation surgery even in patients with inflammatory arthritis. PS had a better diagnostic utility than FS suggesting that areas of acute inflammation may be scattered and may not always be captured in the specimens taken for FS.

Diagnosis Of Persistent Infection In Prosthetic Two-Stage Exchange: PCR analysis of Sonication fluid From Bone Cement Spacers.

Introduction: When treating periprosthetic joint infections with a two-stage procedure, antibiotic-impregnated spacers are used in the interval between removal of prosthesis and reimplantation. According to our experience, cultures of sonicated spacers are most often negative. The objective of our study was to investigate whether PCR analysis would improve the detection of bacteria in the spacer sonication fluid.Methods: A prospective monocentric study was performed from September 2014 to January 2016. Inclusion criteria were two-stage procedure for prosthetic infection and agreement of the patient to participate in the study. Beside tissues samples and sonication, broad range bacterial PCRs, specific S. aureus PCRs and Unyvero-multiplex PCRs were performed on the sonicated spacer fluid.Results: 30 patients were identified (15 hip, 14 knee and 1 ankle replacements). At reimplantation, cultures of tissue samples and spacer sonication fluid were all negative. Broad range PCRs were all negative. Specific S. aureus PCRs were positive in 5 cases. We had two persistent infections and four cases of infection recurrence were observed, with bacteria different than for the initial infection in three cases.Conclusion: The three different types of PCRs did not detect any bacteria in spacer sonication fluid that was culture-negative. In our study, PCR did not improve the bacterial detection and did not help to predict whether the patient will present a persistent or recurrent infection. Prosthetic 2-stage exchange with short interval and antibiotic-impregnated spacer is an efficient treatment to eradicate infection as both culture- and molecular-based methods were unable to detect bacteria in spacer sonication fluid after reimplantation.

Two-stage Revision Arthroplasty for Management of Chronic Periprosthetic Hip and Knee Infection

In North America, two-stage revision arthroplasty is the treatment of choice for chronic periprosthetic infection of the hip and knee. Controversy exists regarding the diagnosis of persistent infection, cement spacer design, and duration of antibiotic therapy. Erythrocyte sedimentation rate and C-reactive protein tests have no clear cutoff values for detecting infection before reimplantation of hardware, and aspiration for microbial culture can yield false-negative results. Mobile spacers are as effective as static spacers for eradicating infection, but mobile spacers provide better interim function and may help to make the second stage of surgery technically easier. Some articulating spacer designs have fewer reports of spacer dislocation and fracture than do others. Although prolonged antibiotic therapy has been the standard of care for two-stage procedures, some have suggested that a short course of antibiotics is just as effective. When infection persists despite antibiotic therapy, the second stage of revision arthroplasty should be delayed until the first stage of the procedure is repeated.

Laboratory diagnosis of persistent human chlamydial infection

Diagnostic assays for persistent chlamydial infection are much needed to conduct high-quality, large-scale studies investigating the persistent state in vivo, its disease associations and the response to therapy. Yet in most studies the distinction between acute and persistent infection is based on the interpretation of the data obtained by the assays developed to diagnose acute infections or on complex assays available for research only and/or difficult to establish for clinical use. Novel biomarkers for detection of persistent chlamydial infection are urgently needed. Chlamydial whole genome proteome arrays are now available and they can identify chlamydial antigens that are differentially expressed between acute infection and persistent infection. Utilizing these data will lead to the development of novel diagnostic assays. Carefully selected specimens from well-studied patient populations are clearly needed in the process of translating the proteomic data into assays useful for clinical practice. Before such antigens are identified and validated assays become available, we face a challenge of deciding whether the persistent infection truly induced appearance of the proposed marker or do we just base our diagnosis of persistent infection on the presence of the suggested markers. Consequently, we must bear this in mind when interpreting the available data.

Early Surgical Intervention of Peritoneal Dialysis Catheter-Related Pseudomonas Peritonitis

We present two cases of peritoneal dialysis (PD) catheter-related Pseudomonas peritonitis that were poorly responsive to treatment guidelines of antibiotics and early catheter removal, and uncommonly complicated with ongoing intractable infections. An emergency exploratory laparotomy with extensive intraoperative peritoneal lavage and drainage was performed. The patients recovered dramatically and were transferred to hemodialysis permanently. These unusual cases show the possibility of persistent intra-abdominal infection that may extend extra-abdominally. Early diagnosis of persistent infection, timely surgical intervention, and concept of source control are of utmost importance.

Persistent infection with bovine viral diarrhea virus in an alpaca

A 2.5-month-old female alpaca that had been born prematurely was examined because of moderate mucopurulent nasal discharge and high rectal temperature. In addition to pyrexia and clinical signs of disease of the upper portion of the respiratory tract, the cria had inappetence and was in an unthrifty condition. Hematologic abnormalities included low WBC count, low hemoglobin concentration, and low PCV. Samples of blood were submitted for bovine viral diarrhea virus (BVDV) isolation and serologic evaluation. Other adults and newborn crias in the herd were similarly examined. Bovine viral diarrhea virus was detected in the cria, and a diagnosis of persistent infection with BVDV was made at 5.5 months of age. Persistent BVDV infection was suspected in another cria born into the herd but was not identified in any of the adult alpacas. Despite several treatments with antimicrobials, no permanent improvement of the cria's condition was achieved. Because of the poor prognosis, the owners requested euthanasia of the cria; BVDV was isolated from specimens of multiple organs collected at necropsy. To date, BVDV infection in New World camelids has not been regarded as a major disease entity. Findings in the cria of this report illustrate that some strains of BVDV readily infect alpacas. Clinical description of the disease plus clinicopathologic findings suggest that persistent BVDV infection may be greatly overlooked as a cause of chronic anemia and failure to thrive in alpacas.

Bovine Viral Diarrhea Virus in Alpaca: Abortion and Persistent Infection

An alpaca herd in eastern Ontario experienced vague signs of illness, including anorexia and lethargy in 9 animals, 2.5 months after the addition of a chronically ill cria and his dam to the farm. Subsequently 2 alpaca had early pregnancy loss; one aborted at 5.5 months gestation and the other at 7 months gestation. Seventeen were found to have serum antibody to bovine viral diarrhea virus (BVDV), with highest titers to BVDV type 1. The fetus that was aborted at 5.5 months gestation, 3 months after the clinical outbreak, was found to be positive for BVDV on immunohistochemical staining, and noncytopathic BVDV type 1b was isolated. Of the 13 cria born alive that season, a single male underweight alpaca cria, born 9 months after the clinical illnesses, was infected with BVDV type 1b. The cria was positive for BVDV at birth, at 3 and 26 days of age and continued to be positive for noncytopathic BVDV using virus isolation, nested reverse transcription PCR, antigen detection ELISA, and immunohistochemical staining until euthanasia at 46 days of age. The cria remained serum antibody negative to both BVDV type 1 and type 2. A diagnosis of persistent infection was made. This is the first report describing persistent infection with BVDV in an alpaca cria.

Persistent parvovirus B19 infections in humans

Persistent B19 infection may be frequent in man and responsible for a variety of chronic diseases. Clinical and in vitro observations suggest that persistence is the result of a balance over time among virus, target cells, and the immune system. Practically, the diagnosis of persistent infection will require molecular rather than immunologic studies, since inability to produce antibody to virus may be the fundamental defect leading to chronicity