The etiologic diagnosis of infectious discitis is improved by amplification-based DNA analysis

A Rare Case of Streptococcus cristatus Spondylodiscitis Identified by Bacterial 16S rRNA Polymerase Chain Reaction Sequencing: A Case Report and a Review of the Literature

We report here a rare case of spondylodiscitis due to Streptococcus cristatus in a healthy 66-year-old male. Due to an abscess causing neurological deficit, which required immediate surgical intervention, a PCR targeting 16S rRNA was performed on the surgical samples as all blood and tissue cultures remained negative. This molecular assay allowed for the identification of this rare Streptococcus, a member of the mitis group and commensal of the oral cavity, whose pathogenicity remains uncertain although it has been seldom reported in cases of human infections, mostly bacteremia and endocarditis. Notably, our case is distinguished by the absence of comorbidities, although the patient's history was compatible with a dental portal of entry. This case illustrates once more that 16S rRNA PCR can be of great help for documenting the causative pathogen in osteoarticular infections when cultures remain inconclusive. We reviewed in this article the data regarding osteoarticular infections due to S. cristatus and discussed the role of molecular technique in the diagnosis of spondylodiscitis.

Next-generation sequencing (NGS) to determine microbiome of herniated intervertebral disc

BACKGROUND CONTEXT

There is apparent causality between chronic infection of the intervertebral disc and its degenerative process. Although disc is considered a sterile tissue, collected samples of uninfected patients sent to culture testing resulted positive.

PURPOSE

The purpose of this study was to analyze the microbiome of the intervertebral disc by using and validating the next-generation sequencing (NGS) molecular test, controlled with tissue culture and clinical presentation of patients.

STUDY DESIGN/SETTING

Prospective study of consecutive patients in a hospital.

PATIENT SAMPLE

Patients with lumbar disc herniation undergoing open microdiscectomy aging 18 to 65 years.

OUTCOME MEASURES

NGS, tissue culture METHODS: Subjects undergoing open decompression surgery for lumbar disc herniation were consecutively included and clinically followed for one year. Three samples of the excised herniated disc fragment were sent to tissue culture and another sample of the disc was sent to NGS test for microbiome analysis. Control samples of the ligamentum flavum and deep muscle were collected and sent to culture.

RESULTS

A total of 17 patients were included. All patients presented negative cultures of the removed disc samples, as well as negative cultures of muscle and yellow ligament. None of the patients evolved to clinical infection one year after surgery, nor presented significant alteration of laboratory markers. NGS mapped a mean of 14,645 (range 6,540 to 27,176) DNA sequences for each disc sample of each patient. There were a total of 45 different bacteria genera remnants with different amount of DNA sequences detected. There was a mean of 8 (range 3-17) different bacterial elements in each sample of intervertebral disc. Three bacteria were present in all disc samples (Herbaspirillum, Ralstonia, and Burkolderia). Although there were a considerable mean number of bacterial sequences mapped in each disc sample, the amount of sequences related to bacteria was low. Cutibacterium acnes elements was not found in any disc microbiome analysis.

CONCLUSIONS

NGS has been proven to adequately determine bacterial DNA presence within the intervertebral disc. C. acnes was not isolated in culture neither in microbiome analysis of patients with lumbar disc herniation. We cannot confirm disc sterility since, even if it does not cause infection, there is bacterial or remnant DNA in herniated discs.

Diagnosis of vertebral osteomyelitis

Native vertebral osteomyelitis (NVO) is a potentially fatal infection which has seen a gradual increase in its incidence over the past decades. The infection is insidious, presenting with symptoms of back pain. Fever is present in about 60 % of patients. Prompt diagnosis of NVO is important to prevent the development of complications. Numerous laboratory and imaging tools can be deployed to accurately establish the diagnosis. Imaging techniques such as magnetic resonance, nuclear imaging, and computed tomography are essential in diagnosing NVO but can also be useful in image-guided biopsies. Laboratory tools include routine blood tests, inflammatory markers, and routine culture techniques of aspirated specimens. Recent advances in molecular techniques can assist in identifying offending pathogen(s). In this review, we detail the arsenal of techniques that can be utilized to reach a diagnosis of NVO.

Serum and Synovial Biomarkers for the Diagnosis of Implant-Associated Infection After Orthopedic Surgery

Implant-associated infection is one of the most devastating complications following orthopedic surgery. Early identification is crucial for treatment. Currently, however, a reliable diagnostic tool is lacking, partly due to disparate bacteria colonies (virulent vs non-virulent), difficulty in distinguishing infection from inflammatory disease, and highly diverse diagnostic thresholds and testing methods. Given the importance of biomarkers in the initial screening for the infection, an extensive effort has been made to develop serum and synovial biomarkers. In this review, the authors summarize the results from the most relevant studies to provide comprehensive information on biomarkers for the diagnosis of implant-associated infection. [Orthopedics. 2021;44(2):e158-e166.].

A novel intraoperative technique seeding morselized bone tissue into pediatric blood culture bottles improves microbiological diagnosis in patients with foot and ankle osteomyelitis

BACKGROUND

Osteomyelitis, particularly cases involving the foot and ankle, is a challenging situation that frequently leads to amputations and major sequelae. Targeted antibiotics treating an identified pathogen are key to a successful outcome; however, traditional culture methods for bone tissue have poor sensitivity. This study prospectively compared a novel method for obtaining and processing infected bone tissue with the standard technique.

METHODS

107 patients presenting with a diagnosis of osteomyelitis of the foot and ankle between 2008 and 2017 were prospectively included. Diagnosis was done according to clinical, laboratory and imaging findings. We obtained paired samples of bone tissue from all patients; they were processed through a usual culture method (UCM), but they were also morselized and seeded into pediatric blood culture bottles (PBCBs). We compared the culture yield and the number of agents detected using both the McNemar and the Mann-Whitney tests, respectively.

RESULTS

We studied 107 patients (63 with diabetic foot infection and 44 with nondiabetic osteomyelitis). The causative agent was identified in 60.7% of cases using the UCM and in 97.2% of cases using PBCBs (p < 0.001). We detected a mean of 1.05 ± 1.03 bacteria using the UCM and 1.67 ± 0.92 bacteria using PBCBs (p < 0.01).

CONCLUSION

Cultures using morselized bone seeded in PBCBs identified the causative agent in a significantly larger percentage than the UCM. Additionally, this method identified a larger number of pathogen agents. A better agent identification method has advantages such as identifying more specific antibiotic treatment in these cases.

Spinal Infections: An Update

Spinal infection poses a demanding diagnostic and treatment problem for which a multidisciplinary approach with spine surgeons, radiologists, and infectious disease specialists is required. Infections are usually caused by bacterial microorganisms, although fungal infections can also occur. The most common route for spinal infection is through hematogenous spread of the microorganism from a distant infected area. Most patients with spinal infections diagnosed in early stages can be successfully managed conservatively with antibiotics, bed rest, and spinal braces. In cases of gross or pending instability, progressive neurological deficits, failure of conservative treatment, spinal abscess formation, severe symptoms indicating sepsis, and failure of previous conservative treatment, surgical treatment is required. In either case, close monitoring of the patients with spinal infection with serial neurological examinations and imaging studies is necessary.

Benefits of Polymerase Chain Reaction Combined With Culture for the Diagnosis of Bone and Joint Infections: A Prospective Test Performance Study

Background

The microbiological diagnosis of bone and joint infections (BJI) currently relies on cultures, and the relevance of molecular methods is still debated. The aim of this study was to determine whether polymerase chain reaction (PCR) could improve the etiological diagnosis of BJI.

Methods

A prospective study was conducted during a 4-year period at Lariboisiere University Hospital (Paris, France), including patients with suspicion of infectious spondylodiscitis, septic arthritis, prosthetic joint infections, and respective noninfected groups. Clinical and radiological data were collected at inclusion and during follow-up. All samples were analyzed by conventional cultures and 16S ribosomal deoxyribonucleic acid (rDNA) gene (16S-PCR). Specific cultures and PCR targeting Mycobacterium tuberculosis were also performed for spondylodiscitis samples. Case records were subsequently analyzed by an independent expert committee to confirm or invalidate the suspicion of infection and definitively classify the patients in a case or control group. The sensitivity of the combination of culture and PCR was compared with culture alone.

Results

After expert committee analysis, 105 cases of BJI cases and 111 control patients were analyzed. The most common pathogens of BJI were staphylococci (30%), M tuberculosis (19%), and streptococci (14%). Adding PCR enhanced the sensitivity compared with culture alone (1) for the diagnosis of M tuberculosis spondylodiscitis (64.4% vs 42.2%; P < .01) and (2) for nonstaphylococci BJI (81.6% vs 71.3%; P < .01). It is interesting to note that 16S-PCR could detect BJI due to uncommon bacteria such as Mycoplasma and fastidious bacteria.

Conclusions

Our study showed the benefit of 16S-PCR and PCR targeting M tuberculosis as add-on tests in cases of suspected BJI.

Evaluation of Challenges in Diagnosis of Spontaneous Subacute Pyogenic Spondylodiscitis in Immunocompetent Patients: Experiences from a Tertiary Care Center

Study Design

Prospective clinical study.

Purpose

We evaluated the challenges faced during diagnosis and management of patients with subacute pyogenic discitis and discussed various clues in clinical history, radiologic and hematologic parameters of these patients that helped in establishing their diagnosis.

Overview of Literature

Present literature available shows that in patients with subacute spondylodiscitis and infection with less virulent organisms, the clinical picture often is confusing and the initial radiologic and hematologic studies do not contribute much toward establishing the diagnosis.

Methods

Demographic pattern, predisposing factors, clinical presentation, comorbidities, microbiology, treatment, neurologic recovery, and complications of 11 patients were prospectively reviewed regarding their contribution toward the conformation of diagnosis of subacute pyogenic discitis.

Results

Mean age at presentation was 46.0 years with average preoperative Oswestry Disability Index and Visual Analog Scale scores of 83.4 and 7.18, respectively. Mean follow-up duration was 12.0 months. The most common site of infection was the lumbar spine, followed by the thoracic spine (n=1). Infective organisms were isolated in only 45% of cases. Staphylococcus aureus was the most common causative organism isolated.

Conclusions

Diagnosing subacute spondylodiscitis in a patient presenting with subacute low backache poses a diagnostic challenge. Clinical and radiologic picture are deceiving, and bacteriologic results often are negative, further complicating the picture. A detailed medical history along with clinical, radiologic, and biochemical parameters prevents missing the diagnosis. Serial serum Creactive protein and alkaline phosphatases were more reliable blood parameters in cases of subacute presentation.

Diagnostics and antibiotic therapy for spondylodiscitis

Purpose. Spondylodiscitis as a rare disease has increased in recent years; there are only a few recommendations regarding the diagnostics and treatment. The objective of this retrospective study was to characterise these patients and identify factors for a favourable healing process - with an emphasis on antibiotic therapy.Methodology. Findings/treatment regimens for all patients with spondylodiscitis treated at a tertiary care hospital in 2012/2013 were recorded. The patients were classified into two groups, depending on the healing process.Results. Fifty-seven patients met the clinical/radiological criteria for spondylodiscitis. The main symptom was massive back pain, combined with a moderate CRP elevation (median 96 mg l^-1), and occasionally fever (39 %). CT-guided aspiration - in addition to blood cultures - improved the detection rate for the causative pathogen from 49 to 82 %. Thirty patients had a favourable clinical course; 25 had an unfavourable clinical course (prolonged clinical course, recurrence, death). Pathogen-specific antibiotic therapy had a decisive effect on the clinical course: initial high-dose intravenous therapy for at least 14 days was associated significantly more often with a favourable clinical course (90 vs 30 % after 24 months, P<0.001). Fourteen days after the start of treatment, marked pain reduction and a CRP reduction of at least 50 % were good prognostic parameters and markers of effective antibiotic therapy.Conclusion. Pathogen detection and establishment of an optimal antibiotic regimen are cornerstones of successful conservative therapy for spondylodiscitis. Targeted initial intravenous therapy for at least 14 days with a bactericidal antibiotic leads to a better clinical course.

Spondylodiscitis revisited

Spondylodiscitis may involve the vertebral bodies, intervertebral discs, paravertebral structures and spinal canal, with potentially high morbidity and mortality rates.

A rise in the susceptible population and improved diagnosis have increased the reported incidence of the disease in recent years.

Blood cultures, appropriate imaging and biopsy are essential for diagnosis and treatment.

Most patients are successfully treated by conservative means; however, some patients may require surgical treatment.

Surgical indications include doubtful diagnosis, progressive neurological deficits, progressive spinal deformity, failure to respond to treatment, and unresolved pain.

Cite this article: EFORT Open Rev 2017;2:447–461. DOI: 10.1302/2058-5241.2.160062

Pyogenic Vertebral Osteomyelitis: Clinical Features, Diagnosis, and Treatment

Pyogenic vertebral osteomyelitis (PVO) may result in neurological deficits and sequelae, so early diagnosis and appropriate treatment are critical. Many previous studies on PVO exist, but our paper has aimed to comprehensively summarize the clinical aspects of PVO. Through review of the vast literature on the clinical research of PVO an overview of the clinical characteristics, diagnostic methods, treatment and prognosis is provided.

Ribosomal PCR assay of excised intervertebral discs from patients undergoing single-level primary lumbar microdiscectomy

PURPOSE

To determine the presence of infectious microorganisms in the herniated discs of immunocompetent patients, using methodology that we hoped would be of higher sensitivity and specificity than has been reported in the past. Recent studies have demonstrated a significant rate of positive cultures for low virulent organisms in excised HNP samples (range 19-53%). These studies have served as the theoretical basis for a pilot trial, and then, a well done prospective randomized trial that demonstrated that systemic treatment with antibiotics may yield lasting improvements in a subset of patients with axial back pain. Whether the reported positive cultures in discectomy specimens represent true positives is as yet not proven, and critically important if underlying the basis of therapeutic approaches for chronic low back pain.

METHODS

This consecutive case series from a single academic center included 44 patients with radiculopathy and MRI findings of lumbar HNP. Patients elected for lumbar microdiscectomy after failure of conservative management. All patients received primary surgery at a single spinal level in the absence of immune compromise. Excised disc material was analyzed with a real-time PCR assay targeting the 16S ribosomal RNA gene followed by amplicon sequencing. No concurrent cultures were performed. Inclusion criteria were as follows: sensory or motor symptoms in a single lumbar nerve distribution; positive physical examination findings including positive straight leg raise test, distributional weakness, and/or a diminished deep tendon reflexes; and magnetic resonance imaging of the lumbar spine positive for HNP in a distribution correlating with the radicular complaint.

RESULTS

The PCR assay for the 16S rRNA sequence was negative in all 44 patients (100%). 95% CI 0-8%.

CONCLUSIONS

Based on the data presented here, there does not appear to be a significant underlying rate of bacterial disc infection in immunocompetent patients presenting with radiculopathy from disc herniation.

Pathogen Identification in Suspected Cases of Pyogenic Spondylodiscitis

Pyogenic spinal infection continues to represent a worldwide problem. In approximately one-third of patients with pyogenic spondylodiscitis, the infectious agent is never identified. Of the cases that lead to organismal identification, bacteria are more commonly isolated from the spine rather than fungi and parasites. This study applied universal prokaryotic 16S rRNA PCR as a rapid diagnostic tool for the detection of bacterial agents in specimens from patients suspected of pyogenic spondylodiscitis. Gram and Ziehl-Neelsen staining were used as a preliminary screening measure for microbiologic evaluation of patient samples. PCR amplification targeting 16S rRNA gene was performed on DNA extracted from 57 cases including specimens from epidural abscesses, vertebral, and disc biopsies. Positive samples were directly sequenced. MRI findings demonstrated that disc destruction and inflammation were the major imaging features of suspected pyogenic spondylodiscitis cases, as 44 cases showed such features. The most common site of infection was the lumbar spine (66.7%), followed by thoracic spine (19%), the sacroiliac joint (9.5%), and lumbar-thoracic spine (4.8%) regions. A total of 21 samples amplified the 16S rRNA-PCR product. Sanger sequencing of the PCR products identified the following bacteriological agents: Mycobacterium tuberculosis (n = 9; 42.9%), Staphylococcus aureus (n = 6; 28.5%), Mycobacterium abscessus (n = 5; 23.8%), and Mycobacterium chelonae (n = 1; 4.8%). 36 samples displayed no visible 16S rRNA PCR signal, which suggested that non-bacterial infectious agents (e.g., fungi) or non-infectious processes (e.g., inflammatory, or neoplastic) may be responsible for some of these cases. The L3–L4 site (23.8%) was the most frequent site of infection. Single disc/vertebral infection were observed in 9 patients (42.85%), while 12 patients (57.15%) had 2 infected adjacent vertebrae. Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) inflammatory markers were noted in majority of the patients. In conclusion, microbiological methods and MRI findings are vital components for the proper diagnosis of pyogenic spondylodiscitis. Our findings suggest that molecular methods such as clinical application of 16S rRNA PCR and sequencing may be useful as adjunctive diagnostic tools for pyogenic spondylodiscitis. The rapid turnaround time of 16S rRNA PCR and sequencing submission and results can potentially decrease the time to diagnosis and improve the therapeutic management and outcome of these infections. Although S. aureus and M. tuberculosis were the most common causes of pyogenic spinal infections in this study, other infectious agents and non-infectious etiologies should be considered. Based on study results, we advise that antibiotic therapy should be initiated after a definitive etiological diagnosis.

Spontaneous corynebacterium spondylodiskitis in an immunocompetent patient: A case report and literature review

BACKGROUND

Spontaneous Corynebacterium spondylodiskitis is an unusual diagnosis of spondylodiskitis, especially in healthy patients without any significant past medical history.

MATERIALS AND METHODS

We describe the case of a 78-year-old man with progressive low back pain for 3 months, irradiating down the lower limbs through L5 and S1 root pathways, associated with distal muscle weakness in both lower limbs. He had no history of trauma or medical problems. Laboratory investigation revealed elevated serum C-reactive protein (CRP) and erythrocyte sedimentation rate, without leukocytosis. The magnetic resonance findings demonstrated an extensive L5-S1 spondylodiskitis and L4-L5 anterolisthesis. Prior to spinopelvic fixation and posterolateral fusion, a substantial debridement was performed. The obtained tissue samples were submitted to pathological and microbiological studies, which identified Corynebacterium infection.

RESULTS

One month after surgery, the pain diminished dramatically and the CRP titer diminished significantly.

CONCLUSION

Although cases are very rare, spontaneous Corynebacterium spondylodiskitis, with substantial invasion of the spine, may develop in patients lacking any history of medical or surgical problems.

Comparison of synovial fluid culture and 16S rRNA PCR in dogs with suspected septic arthritis

OBJECTIVE

To prospectively compare the sensitivity and specificity of 16S rRNA PCR with culture for identifying the causative organism in synovial fluid obtained from dogs with suspected septic arthritis.

METHODS

Synovial fluid cytology, PCR analysis and aerobic, anaerobic and Mycoplasma culture of samples from the affected joints of 18 dogs presenting with suspected septic arthritis were performed. Synovial fluid samples from the corresponding contralateral joints of 7 dogs were also analysed as negative controls.

RESULTS

There was no significant difference between the sensitivity of bacterial detection via culture (63.2%) versus PCR (73.7%) of synovial fluid (P=0.728) or between culture and combined PCR and culture (89.5%) of synovial fluid (P=0.124). The specificity of PCR (42.9%) was significantly lower than culture specificity (100%) (P=0.07).

CONCLUSION

Although 16S PCR may hold potential as an ancillary diagnostic test for identifying the causative organism in dogs with septic arthritis, our study failed to demonstrate improved accuracy compared with traditional synovial fluid culture.

A Retrospective Analysis of the Management of Postoperative Discitis: A Single Institutional Experience

Study Design

Retrospective study.

Purpose

The aim of the study was to study the impact and outcome of conservative management and surgical intervention in cases of postoperative discitis.

Overview of Literature

Postoperative discitis is a rare but often misdiagnosed cause of failed back syndrome. There is paucity of literature regarding management guidelines of postoperative discitis.

Methods

The study was carried out over a period of 6 years. Eighteen patients with postoperative discitis were included in the study.

Results

Conservative management with antibiotics, analgesics and bed rest were started in all the study cases. Posterior transpedicular fixation after re-exploration debridement and curettage of disc space granulation tissue was conducted in five patients in whom conservative management failed.

Conclusions

Early diagnosis and appropriate management is the key to effective treatment of postoperative discitis. Conservative management leads to excellent results in majority of cases. Surgical intervention with posterior interbody fusion and debridement is helpful when conservative treatment fails.

Actinomyces and related organisms in human infections

Actinomyces israelii has long been recognized as a causative agent of actinomycosis. During the past 3 decades, a large number of novel Actinomyces species have been described. Their detection and identification in clinical microbiology laboratories and recognition as pathogens in clinical settings can be challenging. With the introduction of advanced molecular methods, knowledge about their clinical relevance is gradually increasing, and the spectrum of diseases associated with Actinomyces and Actinomyces-like organisms is widening accordingly; for example, Actinomyces meyeri, Actinomyces neuii, and Actinomyces turicensis as well as Actinotignum (formerly Actinobaculum) schaalii are emerging as important causes of specific infections at various body sites. In the present review, we have gathered this information to provide a comprehensive and microbiologically consistent overview of the significance of Actinomyces and some closely related taxa in human infections.

Escherichia coli Vertebral Osteomyelitis Diagnosed According to Broad-range 16S rRNA Gene Polymerase Chain Reaction (PCR)

Identifying the causative agent of pyogenic osteomyelitis is often challenging, especially when antibiotics are administered before a biopsy. We herein present a case of osteomyelitis in the cervical vertebrae presenting with progressive paralytic symptoms, in which we successfully identified Escherichia coli from a biopsy specimen using broad-range 16S rRNA gene polymerase chain reaction (PCR) even though sensitive antibiotics had been used for more than 50 days before the biopsy. Broad-range 16S rRNA gene PCR is a useful diagnostic method, especially when prebiopsy antibiotics are unavoidably used for a clinically unstable state.

Complementarity between targeted real-time specific PCR and conventional broad-range 16S rDNA PCR in the syndrome-driven diagnosis of infectious diseases

Molecular tools have shown an added value in the diagnosis of infectious diseases, in particular for those caused by fastidious intracellular microorganisms, or in patients receiving antibiotics before sampling. If 16S rDNA amplification had been gradually implemented in microbiology laboratories, specific real-time polymerase chain reaction (PCR) would have permitted an increase in the sensitivity of molecular methods and a reduction of contamination. Herein, we report our experience in the diagnosis of infectious diseases over two years, during which 32,948 clinical samples from 18,056 patients were received from France and abroad. Among these samples, 81,476 PCRs were performed, of which 1,192 were positive. Molecular techniques detected intracellular microorganisms in 31.3 % of respiratory samples, 27.8 % of endocarditis samples and 51.9 % of adenitis samples. Excluding intracellular bacteria, 25 % of the positive samples in this series were sterile in culture. Conventional broad-range PCR permitted the identification of fastidious and anaerobic microorganisms, but specific real-time PCR showed a significant superiority in the diagnosis of osteoarticular infections, in particular for those caused by Kingella kingae and Staphylococcus aureus, and for endocarditis diagnosis, specifically when Streptococcus gallolyticus and Staphylococcus aureus were involved. The sensitivity of conventional broad-range PCR was 62.9 % concerning overall diagnoses for which both techniques had been performed. These findings should lead microbiologists to focus on targeted specific real-time PCR regarding the clinical syndrome. Finally, syndrome-driven diagnosis, which consists of testing a panel of microorganisms commonly involved for each syndrome, permitted the establishment of 31 incidental diagnoses.

First report of spondylodiscitis due to vancomycin heteroresistant Staphylococcus capitis in immunocompetent host

We report a successfully treated case of spondylodiscitis and bloodstream infection due to vancomycin heteroresistant Staphylococcus capitis, in an adult immunocompetent patient with multiple antibiotics intolerance. S. capitis is rarely involved in osteomyelitis and, to our knowledge, this is the first report of vancomycin heteroresistance phenomenon in an S. capitis strain causing spondylodiscitis.

Vertebral discitis after laparoscopic resection rectopexy: a rare differential diagnosis

Vertebral discitis usually arises from haematogenous spread of pathogens to the discs and bones. Vertebral discitis can rarely occur as a complication after laparoscopic operations with fixating sutures on the promontory. We report the case of an 81-year-old woman who underwent a laparoscopic resection rectopexy because of rectal prolapse. Weeks after the operation, the patient developed lower back pain with radiation to both legs not responding to symptomatic therapy. Two months later, a magnetic resonance imaging of the lumbar spine showed vertebral osteomyelitis and discitis. A fixation on the promontory may be sufficiently traumatic to the spine to pave the way for subsequent infection. A high index of suspicion should be raised in patients with persistent, severe back pain. Anamnesis, imageing and an adequate specimen from the affected area for microbiological analysis are crucial for timely diagnosis and appropriate management involving targeted and prolonged antimicrobial therapy.

A Highly Rare Cause of Lumbar Spondylodiscitis with Epidural Abscess: Actinomyces israelii

Actinomyces species may lead to slowly progressive infection of almost any site once mucosal breakdown exists; hence, it has the name “great pretender.” Its diagnosis may be unthinkable unless proper cultures/histologies are taken. We describe a patient with lumbar spondylodiscitis and epidural abscess. This is an exceptional another disease by actinomycosis.

Systematic PCR detection in culture-negative osteoarticular infections

BACKGROUND

Identification of microorganisms is crucial for the successful treatment of osteoarticular infections. Molecular methods are more sensitive than culture-dependent methods but may suffer from lack of specificity.

METHODS

We studied a large series of 3840 bone and joint culture-negative samples collected from 2308 patients hospitalized in Marseille University Hospitals from November 2007 to October 2009. The samples were systematically cultured for 15 days, and conventional broad-range polymerase chain reaction (PCR) (16S rDNA and 18S rDNA) as well as real-time PCR assays targeting human Bglobin, Staphylococcus aureus, and Kingella kingae were realized on one culture-negative specimen.

RESULTS

Specimens from 741 patients (32.1%) tested positive by culture, including 38 in which bacteria grew only after 6 days of incubation. PCR was positive in 141 (9%) culture-negative specimens. Microorganisms identified by PCR were classified into 2 groups: fastidious bacteria (n = 35), mostly anaerobes in adult patients, and K. kingae in children; and nonfastidious bacteria (n = 106), mostly S. aureus (32.7%). A discrepancy between a positive PCR result for S. aureus and a negative culture were explained by previous antibiotherapy in 31.4% of cases. Our study highlights the usefulness of systematic 16S rDNA gene PCR for the diagnosis of bone and joint infections in culture-negative patients, thus enabling the administration of specific antibiotic treatments.

CONCLUSIONS

We recommend the use of conventional broad-range PCR for culture-negative bone and joint specimens, as well as S. aureus-specific PCR for adults and K. kingae-specific PCR for children. 18S rDNA PCR should be reserved only for specific cases.

Invasive Staphylococcus aureus infections in diabetes mellitus

Staphylococcus aureus, the most virulent of the many staphylococcal species, has remained a major cause of morbidity and mortality despite the availability of numerous effective anti-staphylococcal antibiotics. S. aureus causes disease through both toxin-mediated and non-toxin-mediated mechanisms. This organism is responsible for both healthcare associated and community-based infections ranging from relatively minor skin and soft tissue infections to severe life threatening systemic infections. Patients with diabetes mellitus are at increased risk of invasive S. aureus infections. This article focuses on the spectrum of invasive S. aureus infections and discusses the clinical features, investigations and management of these infections in patients with diabetes mellitus.

Duplex quantitative real-time PCR assay for the detection and discrimination of the eggs of Toxocara canis and Toxocara cati (Nematoda, Ascaridoidea) in soil and fecal samples

Background

Toxocarosis is a zoonotic disease caused by Toxocara canis (T. canis) and/or Toxocara cati (T. cati), two worldwide distributed roundworms which are parasites of canids and felids, respectively. Infections of humans occur through ingestion of embryonated eggs of T. canis or T. cati, when playing with soils contaminated with dogs or cats feces. Accordingly, the assessment of potential contamination of these areas with these roundworms eggs is paramount.

Methods

A duplex quantitative real-time PCR (2qPCR) targeting the ribosomal RNA gene internal transcribed spacer (ITS2) has been developed and used for rapid and specific identification of T. canis and T. cati eggs in fecal and soil samples. The assay was set up on DNA samples extracted from 53 adult worms including T. canis, T. cati, T. leonina, Ascaris suum (A. suum) and Parascaris equorum (P. equorum). The assay was used to assess the presence of T. cati eggs in several samples, including 12 clean soil samples spiked with eggs of either T. cati or A. suum, 10 actual soil samples randomly collected from playgrounds in Brussels, and fecal samples from cats, dogs, and other animals. 2qPCR results on dogs and cats fecal samples were compared with results from microscopic examination.

Results

2qPCR assay allowed specific detection of T. canis and T. cati, whether adult worms, eggs spiked in soil or fecal samples. The 2qPCR limit of detection (LOD) in spiked soil samples was 2 eggs per g of soil for a turnaround time of 3 hours. A perfect concordance was observed between 2qPCR assay and microscopic examination on dogs and cats feces.

Conclusion

The newly developed 2qPCR assay can be useful for high throughput prospective or retrospective detection of T.canis and/or T. cati eggs in fecal samples as well as in soil samples from playgrounds, parks and sandpits.

Spondylodiscitis: update on diagnosis and management

Spondylodiscitis, a term encompassing vertebral osteomyelitis, spondylitis and discitis, is the main manifestation of haematogenous osteomyelitis in patients aged over 50 years. Staphylococcus aureus is the predominant pathogen, accounting for about half of non-tuberculous cases. Diagnosis is difficult and often delayed or missed due to the rarity of the disease and the high frequency of low back pain in the general population. In this review of the published literature, we found no randomized trials on treatment and studies were too heterogeneous to allow comparison. Improvements in surgical and radiological techniques and the discovery of antimicrobial therapy have transformed the outlook for patients with this condition, but morbidity remains significant. Randomized trials are needed to assess optimal treatment duration, route of administration, and the role of combination therapy and newer agents.

Development and validation of a real-time quantitative PCR assay for rapid identification of Bacillus anthracis in environmental samples

A real-time polymerase chain reaction (PCR) assay was developed for rapid identification of Bacillus anthracis in environmental samples. These samples often harbor Bacillus cereus bacteria closely related to B. anthracis, which may hinder its specific identification by resulting in false positive signals. The assay consists of two duplex real-time PCR: the first PCR allows amplification of a sequence specific of the B. cereus group (B. anthracis, B. cereus, Bacillus thuringiensis, Bacillus weihenstephanensis, Bacillus pseudomycoides, and Bacillus mycoides) within the phosphoenolpyruvate/sugar phosphotransferase system I gene and a B. anthracis specific single nucleotide polymorphism within the adenylosuccinate synthetase gene. The second real-time PCR assay targets the lethal factor gene from virulence plasmid pXO1 and the capsule synthesis gene from virulence plasmid pXO2. Specificity of the assay is enhanced by the use of minor groove binding probes and/or locked nucleic acids probes. The assay was validated on 304 bacterial strains including 37 B. anthracis, 67 B. cereus group, 54 strains of non-cereus group Bacillus, and 146 Gram-positive and Gram-negative bacteria strains. The assay was performed on various environmental samples spiked with B. anthracis or B. cereus spores. The assay allowed an accurate identification of B. anthracis in environmental samples. This study provides a rapid and reliable method for improving rapid identification of B. anthracis in field operational conditions.

Campylobacter fetus subspecies fetus spondylodiscitis

Campylobacter spp. are common causes of gastrointestinal infections. Campylobacter fetus is a much rarer pathogen in humans, and usually causes bacteraemia and systemic complications in patients with predisposing conditions. We report a case of spondylodiscitis caused by C. fetus subsp. fetus as revealed by vertebral biopsy culture. This identification was confirmed by sequencing the 16S rRNA gene and by phylogenetic analysis. Treatment consisted of 6 weeks antimicrobial therapy combined with a strict initial immobilization, followed by a re-education program. The patient's recovery was uneventful.

Cervical spondylodiscitis, osteomyelitis, and epidural abscess mimicking a vertebral fracture

BACKGROUND

Spinal vertebral fractures are common in elderly patients, especially after a significant fall. Neck tenderness or neurologic deficits after a fall should increase the suspicion of cervical spinal fracture.

CASE REPORT

A 75-year-old woman complained of 2 weeks of gradually increasing neck and right shoulder pain after a fall. She had an X-ray study that appeared to show an unstable C6-C7 fracture. A computed tomography scan of the neck revealed no fracture and was consistent with spondylodiscitis and osteomyelitis of C6 and C7, with an adjacent epidural abscess and mild cord compression.

CONCLUSION

It is important to consider this diagnosis in patients with a history of infective endocarditis who develop back pain, to minimize morbidity associated with this disorder.

Broad-range PCR as a supplement to culture for detection of bacterial pathogens in patients with a clinically diagnosed spinal infection

We aimed to evaluate broad-range PCR and subsequent sequencing compared to conventional culture in the diagnosis of spinal infection. The method was a prospective study of all patients admitted to Aarhus University Hospital for surgery during a 12-months period with a clinically diagnosed infection of the spine. Samples from patients undergoing surgery for non-infectious causes (malignancy etc.) were included as control group. Specimens were submitted to conventional culture and molecular investigation with 16S rRNA gene amplification and sequence analysis. 38 patients were included in the study (clinically diagnosed spinal infections=18; non-infectious diseases=20). The specificity was excellent for both culture and PCR (95% and 100%, respectively). A true culture positive result was obtained in 50% of patients (9/18) and 61% was positive (11/18) by broad-range PCR. When combined, culture and PCR allowed for a microbiological diagnosis in 72% of patients (13/18). A positive culture was found only in patients treated < or =7 d compared to < or =16 d for PCR. However, PCR and culture result were equally negatively affected by duration of treatment. The combination of culture and broad-range PCR substantially adds to the number of microbiological diagnoses obtained, and improves the clinician's opportunity to tailor therapy to individual patients.

Development and validation of a triplex real-time PCR for rapid detection and specific identification of M. avium sub sp. paratuberculosis in faecal samples

A triplex real-time (TRT-PCR) assay was developed to ensure a rapid and reliable detection of Mycobacterium avium subsp. paratuberculosis (Map) in faecal samples and to allow routine detection of Map in farmed livestock and wildlife species. The TRT-PCR assay was designed using IS900, ISMAP02 and f57 molecular targets. Specificity of TRT-PCR was first confirmed on a panel of control mycobacterial Map and non-Map strains and on faecal samples from Map-negative cows (n=35) and from Map-positive cows (n=20). The TRT-PCR assay was compared to direct examination after Ziehl-Neelsen (ZN) staining and to culture on 197 faecal samples collected serially from five calves experimentally exposed to Map over a 3-year period during the sub-clinical phase of the disease. The data showed a good agreement between culture and TRT-PCR (kappa score=0.63), with the TRT-PCR limit of detection of 2.5 x 10(2)microorganisms/g of faeces spiked with Map. ZN agreement with TRT-PCR was not good (kappa=0.02). Sequence analysis of IS900 amplicons from three single IS900 positive samples confirmed the true Map positivity of the samples. Highly specific IS900 amplification suggests therefore that each single IS900 positive sample from experimentally exposed animals was a true Map-positive specimen. In this controlled experimental setting, the TRT-PCT was rapid, specific and displayed a very high sensitivity for Map detection in faecal samples compared to conventional methods.

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.

Usefulness of broad-range PCR for the diagnosis of osteoarticular infections

PURPOSE OF REVIEW

Conventional methods such as microbiological cultures may lack the sensitivity and specificity to establish definitive diagnosis of osteoarticular infections. Herein, we review the general principles and the usefulness of broad-range PCR to improve the etiological diagnosis of osteoarticular infections.

RECENT FINDINGS

Broad-range PCR followed by sequencing has been successfully developed to identify microorganisms involved in infections when patients have previously received antibiotics or in the presence of slow-growing or intracellular microorganisms. For osteoarticular infections, the studies have shown that the use of this molecular tool increased mainly the identification of Kingella kingae, anaerobic bacteria, and Streptococcus spp. However, it is very important to underline that the interpretation of this molecular tool is critical because of several pitfalls, including contamination causing false-positive results.

SUMMARY

Broad-range PCR followed by sequencing offers several advantages when used to complement culture results for the diagnosis of fastidious bacteria and for patients taking antibiotics. However, its use should be restricted mainly for culture-negative cases when infection is suspected on the basis of clinical signs and symptoms or inflammatory syndrome. Future developments will include the use of real-time PCR in a closed system and pathogen-specific PCR for the molecular diagnosis of osteoarticular infections.

Coagulase-negative Staphylococcus isolated from bloodculture: Causes or contaminants?

Introduction According to the results of different investigations, the opinion that isolate of coagulase-negative staphylococci by bloodcultures represents the blood infection in 10-12% patient. The aim of the work was to determine the number of patients with blood infection-sepsa induced coagulase-negative staphylococci isolated by bloodcultures. Material and methods: The research was done at the Institute for Public Health in Nis. The basic group consisted of 56 patients and coagulase-negative staphylococci were segregated form their bloodcultures. The growth of microorganisms was monitored by the computerized apparatus 'Bactec 9120'. Coagulase-negative staphylococci were identified by the standard microbiologic method and Vitec AMS system. Results Eight patients (14.28%) were found to have minimum two signs of blood infection. S. epidermis was isolated in four patients. S. saprophyticus was isolated in the patients on hemodialysis with implanted urinary catheter. S. capitis was isolated in the patients with infarctus miocardi. S. auricularis was isolated in child who was administered the immunosuppressive therapy before and during hospitalization due to an acute asthmatic attack. The isolate of S. simulans was cultivated from samples of the patients hospitalized due to the febrile state. Discussion A correct interpretation of coagulase-negative staphylococci findings in bloodcultures is an overriding part of medical treatment. The best laboratory indicators of the presence of coagulase-negative staphylococci in blood would be to segregate those of the same kind from two samples at the same time but from different anatomic sites in the presence of clinical signs of blood infection. Conclusion In the investigation conducted at the Public Health Institute-Nis, we determined that bloodcultures isolated coagulase-negative staphylococci represent the blood infection on 14.28% patient.

Veillonella parvula discitis and secondary bacteremia: a rare infection complicating endoscopy and colonoscopy?

We report a case of Veillonella parvula lumbar discitis and secondary bacteremia confirmed by molecular characterization of the 16S rRNA genes. Identification of the organism was essential for an appropriate choice of antimicrobial therapy following the failure of empirical flucloxacillin. Veillonella spp. are normal flora of the gastrointestinal tract, raising the possibility that an endoscopy and colonoscopy performed 8 weeks prior to presentation, during which small intestinal and rectal biopsies were obtained, was the portal of entry. This case highlights the importance of obtaining a microbiologic diagnosis, particularly in patients who previously have had procedures involving instrumentation.