Microbiology and management of joint and bone infections due to anaerobic bacteria

Clinical pointers in Prevotella septic arthritis of the hip: a case report

BACKGROUND

Infective arthritis is an orthopaedic surgical emergency. Staphylococcus aureus remains the commonest causative bacteria across all age groups. Prevotella spp. as a cause of infective arthritis is extremely rare.

CASE REPORT

We present our case of a 30-year-old African male patient who presented with mild signs of infective arthritis of the left hip. His risk factors were his background retroviral disease, intravenous drug abuse, and a previous episode of left hip arthrotomy which healed expectantly with intervention. The current presentation was treated with arthrotomy of the hip, fluid lavage, and skeletal traction based on our clinical findings and the rarity of the presentation was seen to be mobilising non-weight bearing with crutches, and pain-free on the left hip.

CONCLUSION

A high index of suspicion for Prevotella Septic Arthritis (PSA) should be exercised when treating infective arthritis patients with background joint arthropathies, and intravenous drug abuse, especially in individuals with significant immunosuppression and/or recent tooth extraction. Fortunately, although rare an entity, good outcomes can be expected with early diagnosis and classic treatment principles of joint decompression and lavage as well as guided antibiotic therapy.

Clinical relevance of occult infections in spinal pseudarthrosis revision

Background

Occult infections in spinal pseudarthrosis revisions have been reported in the literature, but the relevance of such an infection on patient outcomes is unknown. We aimed to elucidate clinical outcomes and re-revision risks between patients with and without occult infections in spinal revision surgery for pseudarthrosis.

Methods

In this matched case-control study, we identified 128 patients who underwent thoracolumbar revision surgery from 2014–2019 for pseudarthrosis of the spine. Among them, 13 (10.2%) revealed an occult infection (defined by at least two positive intraoperative tissue samples with the same pathogen), and nine of these 13 were available for follow-up. We selected 18 of the 115 controls using a 2:1 fuzzy matching based on fusion length and length of follow-up. The patients were followed up to assess subsequent re-revision surgeries and the following postoperative patient-reported outcome measures (PROMs): overall satisfaction, Oswestry Disability Index, 5-level EQ-5D, and Short Form 36.

Results

Patient characteristics, surgical data, and length of follow-up were equal between both study groups. The rate of re-revision free survival after the initial pseudarthrosis revision surgery was higher in the occult infection group (77.8%) than the non-infectious controls (44.4%), although not significantly (0.22). The total number of re-revision surgeries, including re-re-revisions, was thirteen (in ten patients) in the control and two (in two patients) in the occult infection group (p = 0.08) after a median follow-up of 24 months (range 13-75). Four cases in the control group underwent re-revision for pseudarthrosis compared to none in the infected group. Satisfactory scores were recorded in all PROMs, with similar scores between the two groups.

Conclusions

The presence of an occult infection accompanying spinal pseudarthrosis revision was not inferior to non-infected pseudarthrosis revisions in a matched, small sample size cohort study. This may be explained due to the possibility of targeted treatment of the identified cause of pseudarthrosis.

Femoral osteomyelitis caused by oral anaerobic bacteria with mixed bacteremia of Campylobacter rectus and Parvimonas micra in a chronic periodontitis patient: a case report

Background

Campylobacter rectus is a gram-negative rod, and Parvimonas micra is a gram-positive coccus, both of which are oral anaerobes that cause chronic periodontitis. Chronic periodontitis can cause bacteremia and systemic diseases, including osteomyelitis. Hematogenous osteomyelitis caused by anaerobic bacteria is uncommon, and to date, there have been no reports of mixed bacteremia with C. rectus and P. micra. Here, we report the first case of osteomyelitis of the femur caused by anaerobic bacteria with mixed bacteremia of C. rectus and P. micra caused by chronic periodontitis.

Case presentation

A 75-year-old man with chronic periodontitis, hyperuricemia, and benign prostatic hyperplasia was admitted to the hospital with a fracture of the left femur. The patient had left thigh pain for 4 weeks prior to admission. Left femoral intramedullary nail fixation was performed, and a large amount of abscess and necrotic tissue was found intraoperatively. The cultures of abscess specimens were identified as P. micra, Fusobacterium nucleatum, and C. rectus. C. rectus and P. micra were also isolated from blood cultures. C. rectus was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16 S ribosomal RNA sequencing. Sulbactam-ampicillin was administered for approximately 1 month, after which it was replaced by oral clavulanic acid-amoxicillin for long-term suppressive treatment.

Conclusions

Only five cases of bloodstream infection with C. rectus have been reported, and this is the first report of mixed bacteremia with P. micra. Clinicians should consider that chronic periodontitis caused by rare oral anaerobic bacteria can cause systemic infections, such as osteomyelitis.

A case of Escherichia coli and Peptoniphilus species mixed osteomyelitis successfully identified by MALDI TOF-MS with a review of the literature

BACKGROUND

Peptoniphilus species are Gram-positive anaerobic cocci that are commensals of the human vagina and gut.

METHODS AND RESULTS

We describe a case of mixed Escherichia coli and Peptoniphilus spp. osteomyelitis identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry as Peptoniphilus harei and present a short literature review.

CONCLUSION

To our knowledge, only six cases of P. harei osteomyelitis have been reported to date.

Sonication Fluid Isolation of Peptoniphilus asaccharolyticus After Total Hip Arthroplasty

Peptoniphilus asaccharolyticus is a gram-positive anaerobic coccus found on the skin, vagina, and gut, where it acts as an opportunistic pathogen or as part of polymicrobial infections of chronic wounds or diabetic ulcers. We present a case of a 68-year-old woman who was diagnosed with a late prosthetic hip arthroplasty infection caused by P. asaccharolyticus and isolated from sonication fluid cultures. Despite the fact that evidence is scarce, its role and pathogenicity in more severe infections should not be underestimated.

A CASE OF NEONATAL OSTEOMYELITIS

Acute hematogenous osteomyelitis of neonatal origin is very rare in clinical studies. Early diagnosis and treatment are important to decrease the morbidity. The aim is to provide a reference case for medical practitioners for early diagnosis and treatment of cases like this with symptoms, signs, blood investigations, radiological studies and blood culture outcomes. There have not been any adverse sequelae after effective antibiotic therapy. Timely diagnosis and management of neonatal osteomyelitis are of significant importance.

Medicated Hydroxyapatite/Collagen Hybrid Scaffolds for Bone Regeneration and Local Antimicrobial Therapy to Prevent Bone Infections

Microbial infections occurring during bone surgical treatment, the cause of osteomyelitis and implant failures, are still an open challenge in orthopedics. Conventional therapies are often ineffective and associated with serious side effects due to the amount of drugs administered by systemic routes. In this study, a medicated osteoinductive and bioresorbable bone graft was designed and investigated for its ability to control antibiotic drug release in situ. This represents an ideal solution for the eradication or prevention of infection, while simultaneously repairing bone defects. Vancomycin hydrochloride and gentamicin sulfate, here considered for testing, were loaded into a previously developed and largely investigated hybrid bone-mimetic scaffold made of collagen fibers biomineralized with magnesium doped-hydroxyapatite (MgHA/Coll), which in the last ten years has widely demonstrated its effective potential in bone tissue regeneration. Here, we have explored whether it can be used as a controlled local delivery system for antibiotic drugs. An easy loading method was selected in order to be reproducible, quickly, in the operating room. The maintenance of the antibacterial efficiency of the released drugs and the biosafety of medicated scaffolds were assessed with microbiological and in vitro tests, which demonstrated that the MgHA/Coll scaffolds were safe and effective as a local delivery system for an extended duration therapy—promising results for the prevention of bone defect-related infections in orthopedic surgeries.

First case of periprosthetic joint infection due to Clostridioides difficile in China

Background

Clostridioides difficile usually causes intestinal infections. However, a 75-year-old lady had a periprosthetic joint infection due to this microorganism. We report a C. difficile infection of a prosthetic hip joint. Such an infection is rarely reported around the world.

Case presentation

The elder female patient presented with a 2-year history of right hip pain with movement restriction. Her right leg was shorter than another. The skin around the right hip joint was red and swollen without sinus. Her lab test result showed elevator ESR and CRP. Her X-ray film showed a massive bone defect. The patient had a total hip arthroplasty 16years ago and had a revision 5 years ago. During this hospitalization, her cultures of the synovial fluid and tissue repeatedly grew C. difficile. She improved following two-stage revision surgery and antibiotic treatment. The patient has no recurrence of infection after a one-year follow-up.

Conclusion

A rapid and accurate sample collection is significant for culture results, making an outstanding contribution to the successful treatment.

Isolated Septic Arthritis of the Hip Due to Fusobacterium Nucleatum in An Immunocompetent Adult: A Case Report and Review of the Literature

Introduction:

Hip septic arthritis is more common in children than in adults. Staphylococcus aureus and Streptococcus spp. are commonly found in association with septic joints. In contrast, Fusobacterium nucleatum septic arthritis in adults is extremely rare. To the best of our knowledge, only five cases have been reported in the literature in English, and three of them were cases of periprosthetic joint infection. We report a rare case of hip septic arthritis due to F. nucleatum in an immunocompetent adult.

Case Presentation:

A 56-year-old Asian man with a history of bilateral Perthes’ disease and mild alcoholic liver disease presented to our hospital complaining of worsening right hip pain and difficulty in walking for the previous 3 weeks. On presentation, his temperature was 38.7°C, and laboratory results showed a white blood cell count of 19 200 cells/µL and a C-reactive protein level of 43.56 mg/dL. Hip movements were limited due to pain. Contrast-enhanced computed tomography and magnetic resonance imaging showed fluid retention, suggesting infection. F. nucleatum was detected in the culture test from joint aspirate. Surgical drainage was performed 3 times in combination with antibiotherapy. Finally, we performed two-stage total hip arthroplasty, and the post-operative course was uneventful without implant loosening or infection relapse.

Conclusion:

The patient had a history of Perthes’ disease and had hip osteoarthritis, which may have contributed to the development of hip septic arthritis. We treated this rare case of hip septic arthritis due to F. nucleatum with two-stage revision surgery and antibiotherapy. Clinicians should be aware that F. nucleatum could be the etiologic agent of hip septic arthritis in an immunocompetent patient.

Occult infection in pseudarthrosis revision after spinal fusion

BACKGROUND CONTEXT

Pseudarthrosis after attempted spinal fusion is yet not sufficiently understood and presents a surgical challenge. Occult infections are sometimes observed in patients with pseudarthrosis and no inflammatory signs of infection. The prevalence of such occult infection and its association with patient demographics and inflammatory markers are largely unknown.

PURPOSE

To determine the prevalence of unexpected low-grade infection in spinal pseudarthrosis revision surgery, and to evaluate whether such infection is associated with patient demographics and inflammatory markers.

STUDY DESIGN

Retrospective observational study.

PATIENT SAMPLE

One-hundred-and-twenty-eight patients who underwent thoracolumbar revision surgery due to presumed aseptic pseudarthrosis after spinal instrumentation.

OUTCOME MEASURES

Culture-positive infections or noninfectious pseudarthrosis.

METHODS

Samples were routinely taken for microbiological examination from all adults (n=152) who underwent revision surgery for presumed aseptic thoracolumbar pseudarthrosis between 2014 and 2019. A full intraoperative microbiological workup (at least three intraoperative tissue samples) was done for 128 (84%) patients, and these patients were included in further analyses. Patient characteristics, medical history, inflammatory markers, and perioperative data were compared between those with and without microbiologically-confirmed infection based on samples obtained during pseudarthrosis revision.

RESULTS

The microbiological workup confirmed infection in 13 of 128 cases (10.2%). The predominant pathogen was Cutibacterium acnes (46.2%), followed by coagulase-negative staphylococci (38.5%). The presence of infection was associated with the body mass index (30.9±4.7 kg/m² [infected] vs. 28.2±5.6 kg/m² [controls], p=.049), surgery in the thoracolumbar region (46% vs. 18%, p=.019), and a slightly higher serum C-reactive protein level on admission (9.4±8.0 mg/L vs. 5.7±7.1 mg/L, p=.031). Occult infection was not associated with age, sex, prior lumbar surgeries, number of fused lumbar levels, American Society of Anesthesiologist score, Charlson Comorbidity Index, presence of diabetes mellitus, and smoking status.

CONCLUSIONS

Occult infections were found in 10% of patients undergoing pseudarthrosis revision after spinal fusion, even without preoperative clinical suspicion. Occult infection was associated with higher body mass index, fusions including the thoracolumbar junction, and slightly higher C-reactive protein levels. Intraoperative microbiological samples should be routinely obtained to exclude or identify occult infection in all revision surgeries for symptomatic pseudarthrosis of the spine, as this information can be used to guide postoperative antibiotic treatment.

Revisiting the important role of magnetic resonance imaging (MRI) in long bone acute osteomyelitis: A case report of methicillin resistant Staphylococcus aureus acute tibial osteomyelitis with conventional radiography, computed tomography, and MRI

The tibia is an atypical site of osteomyelitis (OM) in adults, and patients with this infection experience a significant degree of morbidity as well as the need for prolonged aggressive antibiotic therapy. The early diagnosis of OM remains challenging, and often relies on imaging modalities which are of variable sensitivity. We present a case of a 49-year-old male with a methicillin resistant Staphylococcus aureus (MRSa) left tibial OM, contiguous left knee septic arthritis, and concurrent bacteraemia. Eight days after the onset of pain in the left knee and lower limb, conventional radiography and computed tomography (CT) imaging had only subtleties of a soft tissue collection and a knee effusion. A MRI demonstrated significant involvement of his tibial bone with a collection, from which surgical specimens confirmed MRSa. This case demonstrates the difficulty of diagnosing early acute OM with conventional radiography and CT imaging, even after a week of symptoms in the affected limb. Given the poor sensitivity of conventional radiography and CT in the diagnosis of early acute OM, this case report illustrates how MRI is the imaging modality of choice in this setting.

Metagenomic Next-Generation Sequencing Improves Diagnosis of Osteoarticular Infections From Abscess Specimens: A Multicenter Retrospective Study

Background: We conducted this retrospective study to reveal the accuracy of metagenomic next-generation sequencing (mNGS) for diagnosing osteoarticular infections from fresh abscess specimens obtained from patients in an HIV-naive population.

Methods: We retrospectively analyzed hospital records at three participating TB-specialized hospitals for patients admitted with suggestive diagnoses of osteoarticular tuberculosis between January 2018 and August 2019. Abscess specimens obtained from each patient were tested via pathogen culture, GeneXpert Mycobacterium tuberculosis (MTB)/rifampicin (RIF), and mNGS assay.

Results: A total of 82 abscess samples were collected from patients with osteoarticular infections, including 53 cases with (64.6%) bacterial, 21 (25.6%) with mycobacterial, 7 (8.5%) with fungal, and 1 (1.2%) with actinomycetal organisms detected. Analysis of mNGS assay results identified potential pathogens in all cases, with M. tuberculosis complex (MTBC) most frequently isolated, followed by Staphylococcus aureus and Brucella melitensis. Conventional culture testing identified causative pathogens in only 48.4% of samples, a significantly lower rate than the mNGS pathogen identification rate (100%, p < 0.01). Culture-positive group specimens yielded significantly greater numbers of sequence reads than did culture-negative group specimens (p < 0.01). Of patients receiving surgical interventions and mNGS-guided treatment, 76 (92.7%) experienced favorable outcomes by the time of follow-up assessment at 3 months post-treatment. Notably, MTBC detection in two patients experiencing treatment failure suggests that they had mixed infections with MTBC and other pathogens.

Conclusion: Results presented here demonstrate that mNGS has a greater pathogen detection rate in osteoarticular infections than conventional culture-based methods.

Trends in antimicrobial resistance among bacteria causing septic arthritis in adults in a single center: A 15-years retrospective analysis

Septic arthritis (SA) is commonly associated with Staphylococcal or Streptococcal infections. Overtime, there has been a global increase in the distribution of antimicrobial resistance within both Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria such as extended-spectrum beta-lactamase (ESBL) positive Enterobacteriacea. The aim of this study was to determine whether this change in epidemiology similarly affected the distribution of resistant pathogens causing SA. The study was conducted at the Shaare Zedek Medical Center in Jerusalem, Israel. All adult patients diagnosed with SA during 2002-2016 were included in the cohort. Antimicrobial resistance trends were examined over three periods: 2002-2009, 2010-2013, and 2014-2016. Of 85 patients with SA, mean age of patients was 66.8 (± 20.3) years, with male predominance (n = 62, 66%). Most SA cases involved native knee joints and more than 85% (n = 80) were acquired in the community. The most common isolates were S. aureus (n = 38, 45%) and beta-hemolytic streptococci (n = 13, 15%). MRSA SA was diagnosed in 8% of all SA cases (n = 7). An increasing, although non-significant trend in MRSA SA was observed during the study period (p = 0.3). Gram-negative infections were uncommon (n = 14). No ESBL-positive or carbapenem-resistant Enterobacteriacea were detected. Over a 15-year study period, no significant increase in resistant pathogens causing SA was observed. In the era of antibiotic stewardship, these results strengthen our practice of administering narrow-spectrum antimicrobials empirically for SA. However, our findings cannot be generalized to regions with higher rates of MRSA in the community.

Microbiological profile of chronic osteomyelitis with special reference to anaerobic osteomyelitis in a tertiary care hospital of coastal Karnataka

Chronic osteomyelitis is a relapsing, persistent, low-grade inflammation of bone caused by various infectious agents. The present study, conducted over a two-year period, on specimens received from cases of chronic osteomyelitis was, to determine the frequency of isolation of aerobic and anaerobic bacteria and to analyse their antimicrobial susceptibility pattern. Specimens were processed for Gram stain, aerobic and anaerobic culture, and were identified according to standard techniques. Significant growth was observed in 102/204 specimens, in which aerobic growth was observed in 62 (60.8%) and anaerobic in 40 (39.2%). Resistance to metronidazole and clindamycin was observed in 6.7% and 30% of the anaerobic isolates, respectively. None of these were resistant to meropenem. A significant proportion of anaerobic isolates were found to be resistant to commonly used empirical drugs, such as clindamycin, thus necessitating a need for routine anaerobic susceptibility testing.

Clostridium perfringens as an unusual cause of a prosthetic joint infection following total knee arthroplasty

Prosthetic joint infections are a serious complication of prosthetic joint implantations. These infections are generally caused by gram-positive, aerobic pathogens, however anaerobic organisms have been rarely implicated. We describe the case of an adult male who developed a Clostridium perfringens prosthetic joint infection four weeks following a right total knee arthroplasty. The patient had recently had a revision of a vascular graft, and there was initial concern for infectious graft involvement. Our case highlights a successful management pathway that included staged surgical revisions and extended courses of clindamycin and metronidazole, which ultimately spared any vascular complications.

Bacterial resistance trends among intraoperative bone culture of chronic osteomyelitis in an affiliated hospital of South China for twelve years

Background

The purpose of this study was to gather temporal trends on bacteria epidemiology and resistance of intraoperative bone culture from chronic ostemyelitis at an affiliated hospital in South China.

Method

Records of patients with chronic osteomyelitis from 2003 to 2014 were retrospectively reviewed. The medical data were extracted using a unified protocol. Antimicrobial susceptibility testing was carried out by means of a unified protocol using the Kirby-Bauer method, results were analyzed according to Clinical and Laboratory Standards Institute definitions.

Result

Four hundred eighteen cases met our inclusion criteria. For pathogen distribution, the top five strains were Staphylococcus aureus (27.9%); Pseudomonas aeruginosa (12.1%); Enterobacter cloacae (9.5%); Acinetobacter baumanii (9.0%) and Escherichia coli (7.8%). Bacterial culture positive rate was decreased significantly among different year-groups. Mutiple bacterial infection rate was 28.1%. One strain of Staphylococcus aureus was resistant to linezolid and vancomycin. Resistance of Pseudomonas aeruginosa stains to Cefazolin, Cefuroxime, Cefotaxime, and Cefoxitin were 100% nearly. Resistance of Acinetobacter baumanii stains against Cefazolin, Cefuroxime were 100%. Ciprofloxacin resistance among Escherichia coli isolates increased from 25 to 44.4%. On the contrary, resistance of Enterobacter cloacae stains to Cefotaxime and Ceftazidime were decreased from 83.3 to 36.4%.

Conclusions

From 2003 to 2014, positive rate of intraoperative bone culture of chronic osteomyelitis was decreased; the proportion of Staphylococcus aureus was decreased gradually, and our results indicate the importance of bacterial surveilance studies about chronic osteomyelitis.

Validation and Retrospective Clinical Evaluation of a Quantitative 16S rRNA Gene Metagenomic Sequencing Assay for Bacterial Pathogen Detection in Body Fluids

Next-generation sequencing-based 16S rRNA gene metagenomic sequencing (16S MG) technology has tremendous potential for improving diagnosis of bacterial infections given its quantitative capability and culture-independent approach. We validated and used a quantitative 16S MG assay to identify and quantify bacterial species in clinical samples from a wide spectrum of infections, including meningitis, septic arthritis, brain abscess, intra-abdominal abscess, soft tissue abscess, and pneumonia. Twenty clinical samples were tested, and 16S MG identified a total of 34 species, compared with 22 species and three descriptive findings identified by culture. 16S MG results matched culture results in 75% (15/20) of the samples but detected at least one more species in five samples, including one culture-negative cerebrospinal fluid sample that was found to contain Streptococcus intermedius. Shotgun metagenomic sequencing verified the presence of all additional species. The 16S MG assay is highly sensitive, with a limit of detection of 10 to 100 colony-forming units/mL. Other performance characteristics, including linearity, precision, and specificity, all met the requirements for a clinical test. This assay showed the advantages of accurate identification and quantification of bacteria in culture-negative and polymicrobial infections for which conventional microbiology methods are limited. It also showed promises to serve unmet clinical needs for solving difficult infectious diseases cases.

Fusobacterium nucleatum prosthetic hip infection: Case report and review of the literature of unusual anaerobic prosthetic joint infection

The anaerobic Gram-negative rod Fusobacterium nucleatum is an oral commensal and periodontal pathogen that has been associated with a wide variety of infections, yet it is extremely rare to be associated with prosthetic joint infection. After an exhaustive literature review, only two cases of prosthetic joint infection by F. nucleatum have been previously reported. To our knowledge, the case we report on here is the first combined with periprosthetic abscess and related with hemochromatosis. We therefore sought to provide a comprehensive literature review of case reports or series of less commonly encountered anaerobic microorganisms isolated from prosthetic joint infections.

Orthopedic infections caused by obligatory anaerobic Gram-negative rods: report of two cases

Anaerobic bone and joint infections are uncommon, although the number of anaerobic infections is presumably underestimated because of difficulties with isolation and identification of obligate anaerobes. This study describes two cases of complicated Bacteroides fragilis peri-implant infection of the lumbar spine, infection of the hip and osteomyelitis. Bacteria were identified with the use of a mass spectrometer, VITEK MS system. Drug susceptibility was performed with the use of E-test. The EUCAST breakpoints were used for interpretation with B. fragilis ATCC 25285 as a control. In the two described cases clinical samples were collected for microbiological examination intraoperatively and simultaneously empirical treatment was applied. B. fragilis was isolated in monoculture or in a combination with other bacteria. The treatment was continued according to the susceptibility tests. In a case one clindamycin failure was observed and clindamycin resistance of the isolate was likely due to inadequate time of therapy. Difficulties in collecting an adequate samples and culturing anaerobic bacteria cause that not all infections are properly recognized. In a successful therapy, identification and determination of the susceptibility of the pathogen are essential as well as an appropriate surgical debridement.

Treatment for sternoclavicular joint infections: a multi-institutional study

BACKGROUND

Sternoclavicular joint (SCJ) infections are rare and difficult to manage. Surgery is necessary for treatment.

METHODS

A retrospective chart review of the university hospital and Veterans Administration (VA) hospitals of all patients treated for SCJ infections since 2001 was conducted. Fifteen [15] patients were identified and evaluated for the types of infections, risk factors, treatments and survival.

RESULTS

All 15 patients were symptomatic including: pain [13], erythema [9], purulent drainage [3], fever greater than 38.3 °C [2], and leukocytosis [9]. The associated medical problems included: diabetes mellitus (DM), hypertension (HTN) and renal failure. All patients underwent intraoperative joint resection. Sixty-seven percent (67%) of intraoperative wound cultures grew staphylococcus aureus. Fourteen patients were discharged on intravenous antibiotics. The follow-up ranged between 1 week-11 months. Thirteen patients are currently alive without infection. Two patients died: 1 of sepsis and 1 of unknown causes after discharge.

CONCLUSIONS

Symptomatic SCJ infections require surgical intervention. The most common organism was staphylococcus aureus.

The first human clinical case of chronic osteomyelitis caused by Clostridium hydrogeniformans

We present the first case report of osteomyelitis due to Clostridium hydrogeniformans in a previously healthy 18-year-old male. He was admitted to our hospital because of an open contaminated fracture of the right arm after being blown into a drain in a motorbike accident. He underwent surgical debridement and treatment course of cefazolin. Although he responded well to these initial treatments, subcutaneous abscess and ulnar osteomyelitis developed 1 month after discharge. Second debridement was performed and specimens were collected from both the abscess and bone tissues. Only anaerobic culture showed a gas-producing Gam-positive rod. Conventional methods and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry could not accurately identify this organism. However, 16S rRNA gene sequence analysis determined the isolate as C. hydrogeniformans with 99.79% homology. The patient recovered after 90 days of antibiotic treatment, and had no evidence of recurrence. Anaerobic bacteria are more common as causative pathogens in osteomyelitis related to traumatic wounds and Clostridium spp. are particularly associated with open fractures, which is consistent with our case. Although the epidemiology and clinical characteristics of C. hydrogeniformans infection is poorly understood because of the limitations of currently available conventional methods of identification, clinicians need to consider this organism as a causative pathogen in a patient with osteomyelitis in traumatic wounds, especially contaminated by sewer water.

16S rRNA analysis provides evidence of biofilms on all components of three infected periprosthetic knees including permanent braided suture

Bacterial biofilms are the main etiological agent of periprosthetic joint infections (PJI); however, it is unclear if biofilms colonize one or multiple components. Because biofilms can colonize a variety of surfaces, we hypothesized that biofilms would be present on all components. 16S ribosomal RNA (rRNA) gene sequencing analysis was used to identify bacteria recovered from individual components and non-absorbable suture material recovered from three PJI total knee revision cases. Bray-Curtis non-metric multidimensional scaling analysis revealed no significant differences in similarity when factoring component, material type, or suture versus non-suture material, but did reveal significant differences in organism profile between patients (P < 0.001) and negative controls (P < 0.001). Confocal microscopy and a novel agar encasement culturing method also confirmed biofilm growth on a subset of components. While 16S sequencing suggested that the microbiology was more complex than revealed by culture contaminating, bacterial DNA generates a risk of false positives. This report highlights that biofilm bacteria may colonize all infected prosthetic components including braided suture material, and provides further evidence that clinical culture can fail to sufficiently identify the full pathogen profile in PJI cases.

Clinical features of anaerobic orthopaedic infections

Some patient populations and types of orthopaedic surgery could be at particular risk for anaerobic infections. In this retrospective cohort study of operated adult patients with infections from 2004 to 2014, we assessed obligate anaerobes and considered first clinical infection episodes. Anaerobes, isolated from intra-operative samples, were identified in 2.4% of 2740 surgical procedures, of which half (33/65; 51%) were anaerobic monomicrobial infections. Propionibacterium acnes, a penicillin and vancomycin susceptible pathogen, was the predominantly isolated anaerobe. By multivariate analysis, the presence of fracture fixation plates was the variable most strongly associated with anaerobic infection (odds ratio: 2.1, 95% CI: 1.3-3.5). Anaerobes were also associated with spondylodesis and polymicrobial infections. In contrast, it revealed less likely in native bone or prosthetic joint infections and was not related to prior antibiotic use. In conclusion, obligate anaerobes in our case series of orthopaedic infections were rare, and mostly encountered in infections related to trauma with open-fracture fixation devices rather than clean surgical site infection. Anaerobes were often co-pathogens, and cultures most frequently recovered P. acnes. These observations thus do not support changes in current practices such as broader anaerobe coverage for perioperative prophylaxis.

Pyogenic arthritis of native joints due to Bacteroides fragilis: Case report and review of the literature

Pyogenic arthritis of native joints due to Bacteroides fragilis seems to be an infrequent disease. We analyzed the cases diagnosed in a tertiary hospital during a 22-year period and reviewed the literature to summarize the experience with this infectious entity.In our institution, of 308 patients with pyogenic arthritis of native joints, B fragilis was the causative organism in 2 (0.6%) cases. A MEDLINE search (1981-2015) identified 19 additional cases.Of the 21 patients available for review (13 men and 8 women, with a mean age, of 54.4 ± 17 years), 19 (90%) presented a systemic predisposing factor for infection; the most common associated illness was rheumatoid arthritis (8 patients). Bacteremia was documented in 65% (13/20) of cases. In 5 patients (24%), 1 or more concomitant infectious process was found. Metronidazole was the most frequently used antibiotic. Surgical drainage was performed in 11 cases (52%). The overall mortality rate was 5%.Pyogenic arthritis of native joints due to B fragilis is an infrequent disease that mainly affects elderly patients with underlying medical illnesses and in whom bacteremia and the presence of a concomitant infectious process are frequent conditions.

Infections caused by Tissierella praeacuta: A report of two cases and literature review

Herein we report two cases of infections caused by Tissierella praeacuta and a review of the literature. The first case was a septic pseudarthrosis of the left femur after multiple fractures. Two per-operative samples were positive with T. praeacuta. The patient was successfully treated by piperacillin - tazobactam and metronidazole. The second case was a bacteremia in a patient suffering from pyonephrosis and a hepatic abscess. The treatment was meropenem. No relapses were observed in both cases. Identification of the strains using MALDI-TOF coupled to mass spectrometry (MS) (Beckman coulter, France) was inconclusive in the two cases. Identification by 16S rRNA sequencing was then performed. This bacterium was susceptible to beta-lactams, chloramphenicol, rifampicine and metronidazole.

Effects of intra-articular SHINBARO treatment on monosodium iodoacetate-induced osteoarthritis in rats

BACKGROUND

SHINBARO is a refined herbal formulation used to treat inflamed lesions and bone diseases. This study aimed to investigate the anti-osteoarthritic activities of intra-articular administration of SHINBARO and determine its underlying molecular mechanism in a monosodium iodoacetate (MIA)-induced osteoarthritis rat model.

METHODS

Male Sprague-Dawley rats received a single intra-articular injection of MIA into the infrapatellar ligament of the right knee. Subsequently, the rats were treated with normal saline, SHINBARO, and diclofenac once daily for 21 days. Rats treated with normal saline, but not MIA, comprised the control group. Histological changes in the femur of the MIA-induced osteoarthritis rat model were observed by micro-computed tomography scanning and staining with hematoxylin and eosin, and safranin-O fast green. Serum levels of PGE2 and anti-type II collagen antibodies in the MIA-induced osteoarthritis rat model were measured using commercial kits. Protein levels of inflammatory enzymes (iNOS, COX-2), pro-inflammatory cytokines (TNF-α, IL-1β), and inflammatory mediators (NF-κB, IκB) in cartilaginous tissues were determined by western blot analysis.

RESULTS

Intra-articular administration of SHINBARO (IAS) at 20 mg/kg remarkably restrained the decrease in bone volume/total volume, being 28 % (P = 0.0001) higher than that in the vehicle-treated MIA group. IAS (2, 10, and 20 mg/kg) treatment significantly recovered the mean number of objects values with increased percentage changes of 13.5 % (P = 0.147), 27.5 % (P = 0.028), and 44.5 % (P = 0.031), respectively, compared with the vehicle-treated MIA group. The serum level of PGE2 in the IAS group at 20 mg/kg was markedly inhibited by 60.6 % (P = 0.0007) compared with the vehicle-treated MIA group, and the anti-collagen type II antibody level in the IAS group was reduced in a dose-dependent manner. IAS (20 mg/kg) effectively suppressed the induction of inflammation-mediated enzymes (iNOS and COX-2) and pro-inflammatory cytokines (TNF-α and IL-1β). IAS treatment also downregulated the NF-κB level and increased the IκB-α level in the MIA- induced osteoarthritis rat model.

CONCLUSION

SHINBARO inhibited PGE2 and anti-type II collagen antibody production and modulated the balance of inflammatory enzymes, mediators, and cytokines in the MIA-induced osteoarthritis rat model.

Septic arthritis due to Clostridium ramosum

OBJECTIVES

Clostridium species are anaerobic bacilli that are rarely reported as etiologic agents of infectious arthritis. Previous cases of arthritis caused by Clostridium ramosum have not been reported. We describe the first 2 cases of C. ramosum arthritis.

METHODS

We reviewed the etiology of arthritis in our hospital during the previous 15 years.

RESULTS

Both patients had underlying immunocompromising conditions and their infections involved a joint with preexisting disease: patient 1 had rheumatic arthritis and a prosthetic joint; patient 2, chronic renal failure on dialysis and hip osteoarthritis. The infection was hematogenously acquired and the course was indolent but destructive in both the cases. Management included open arthrotomy and resection arthroplasty. The infection had a persisting and relapsing course, and prolonged antibiotic treatment was required. In the literature review, we found 55 previous cases of arthritis caused by Clostridium species between 1966 and 2014; Clostridium perfringens was the most common infecting species; the infection was traumatically acquired in most of the cases. A total of 15 patients have been described with infections caused by C. ramosum; none had septic arthritis. The majority were elderly or immunocompromised adults. Proper collection, transportation and processing of clinical specimens is essential for diagnosing clostridial infections. More information about the best management of clostridial arthritis are needed.

CONCLUSIONS

We describe the first 2 cases of septic arthritis caused by C. ramosum. They shared several pathogenic and clinical features. The possibility of anaerobic arthritis should always be considered when collecting diagnostic specimens. An increasing number of clostridial arthritis cases are likely to be diagnosed in future years.

Diagnosing pelvic osteomyelitis beneath pressure ulcers in spinal cord injured patients: a prospective study

There is no consensus on a diagnostic strategy for osteomyelitis underlying pressure ulcers. We conducted a prospective study to assess the accuracy of multiple bone biopsies and imaging to diagnose pelvic osteomyelitis. Patients with clinically suspected osteomyelitis beneath pelvic pressure ulcers were enrolled. Bone magnetic resonance imaging (MRI) and surgical bone biopsies (three or more for microbiology and one for histology per ulcer) were performed. Bacterial osteomyelitis diagnosis relied upon the association of positive histology and microbiology (at least one positive culture for non-commensal microorganisms or three or more for commensal microorganisms of the skin). From 2011 to 2014, 34 patients with 44 pressure ulcers were included. Bacterial osteomyelitis was diagnosed for 28 (82.3%) patients and 35 (79.5%) ulcers according to the composite criterion. Discrepancy was observed between histology and microbiology for 5 (11.4%) ulcers. Most common isolates were Staphylococcus aureus (77.1%), Peptostreptococcus (48.6%) and Bacteroides (40%), cultured in three or more samples in 42.9% of ulcers for S. aureus and ≥20% for anaerobes. Only 2.8% of ulcers had three or more positive specimens with coagulase-negative staphylococci, group B Streptococcus, and nil with enterococci and Pseudomonas aeruginosa. Staphylococcus aureus, Proteus and group milleri Streptococcus were recovered from one sample in 22.8%, 11.4% and 11.4% of ulcers, respectively. Agreement was poor between biopsies and MRI (κ 0.2). Sensitivity of MRI was 94.3% and specificity was 22.2%. The diagnosis of pelvic osteomyelitis relies on multiple surgical bone biopsies with microbiological and histological analyses. At least three bone samples allows the detection of pathogens and exclusion of contaminants. MRI is not routinely useful for diagnosis.

Clostridial Infections in Children: Spectrum and Management

Clostridia can cause unique histotoxic syndromes produced by specific toxins (e.g., gas gangrene and food poisoning) as well as non-syndromic infections (e.g., abscess, local infections, and blood born infection). Clostridia can also be recovered from various body sites as part of polymicrobial aerobic-anaerobic infection. These include intra-abdominal (peritonitis and abscess), biliary tract, female genital tract, abscess (rectal area and oropharyngeal), pleuropulmonary, central nervous system, and skin and soft-tissue infections. Clostridia were recovered from children with bacteremia of gastrointestinal origin, necrotizing enterocolitis, and sickle cell disease. They have also been isolated in acute and chronic otitis media, chronic sinusitis and mastoiditis, peritonsillar abscesses, and neonatal conjunctivitis. Early and aggressive surgical debridement, decompression, and drainage of affected tissues are critical to successful outcome of histotoxic infections. Effective antimicrobials include penicillin, clindamycin, chloramphenicol, third-generation cephalosporins, carbapenems, and vancomycin.

Ruminococcus gnavus total hip arthroplasty infection in a 62-year-old man with ulcerative colitis

We report the case of a total hip arthroplasty infection caused by Ruminococcus gnavus in a 62-year-old man with ulcerative colitis. The bacterium was perfectly identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Aseptic hip pneumarthrosis following modular total hip arthroplasty: a potential mimic of hip infection

Pneumarthrosis following total hip arthroplasty accompanied by acute hip symptoms is a potentially ominous finding suggesting infection with gas-forming bacteria, a medical emergency. We describe a case of a 61-year-old male presenting to the Emergency Department 43 months following a titanium/titanium (Ti/Ti) modular neck-stem total hip arthroplasty (MTHA) (Wright Medical Systems, Arlington, Tennessee) with acute presentation of hip symptoms and joint gas on radiographs proven to be aseptic hip pneumarthrosis. We review the imaging features of aseptic hip pneumarthrosis following MTHA which have not been elaborated on previously and suggest a less aggressive workup in select cases. We believe emergency radiologists should be aware of this unusual complication as it may mimic a septic hip which may entail an unnecessarily aggressive workup.

Identification of molecular mechanisms used by Finegoldia magna to penetrate and colonize human skin

Finegoldia magna is a Gram-positive anaerobic commensal of the human skin microbiota, but also known to act as an opportunistic pathogen. Two primary virulence factors of F. magna are the subtilisin-like extracellular serine protease SufA and the adhesive protein FAF. This study examines the molecular mechanisms F. magna uses when colonizing or establishing an infection in the skin. FAF was found to be essential in the initial adherence of F. magna to human skin biopsies. In the upper layers of the epidermis FAF mediates adhesion through binding to galectin-7 - a keratinocyte cell marker. Once the bacteria moved deeper into the skin to the basement membrane layer, SufA was found to degrade collagen IV which forms the backbone structure of the basement membrane. It also degraded collagen V, whereby F. magna could reach deeper dermal tissue sites. In the dermis, FAF interacts with collagen V and fibrillin, which presumably helps the bacteria to establish infection in this area. The findings of this study paint a clear picture of how F. magna interacts with human skin and explain how it is such a successful opportunistic pathogen in chronic wounds and ulcers.

Early infection of hip joint prosthesis by Clostridium difficile in an HIV-1 infected patient

Anaerobes are less frequently described as causative pathogen of prosthetic joint infection (PJI). We report the first case of early PJI after hip arthroplasty due to Clostridium difficile in a diabetic and HIV-1 infected patient with bacteremia. Our patient was successfully treated through surgical debridement and prosthesis retention combined with targeted antibiotic therapy.

A Case of Septic Arthritis of the Wrist due to Finegoldia magna

Finegoldia magna (F. magna) has been described as one of the most frequent pathogens in the etiology of postoperative and prosthetic implant associated septic arthritis. In this report, we document our first experience with septic arthritis of the wrist caused by F. magna occurring in a joint with primary disease from prior trauma.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: a new possibility for the identification and typing of anaerobic bacteria

ABSTRACT: 

Anaerobic bacteria predominate in the normal flora of humans and are important, often life-threatening pathogens in mixed infections originating from the indigenous microbiota. The isolation and identification of anaerobes by phenotypic and DNA-based molecular methods at a species level is time-consuming and laborious. Following the successful adaptation of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the routine laboratory identification of bacteria, the extensive development of a database has been initiated to use this method for the identification of anaerobic bacteria. Not only frequently isolated anaerobic species, but also newly recognized and taxonomically rearranged genera and species can be identified using direct smear samples or whole-cell protein extraction, and even phylogenetically closely related species can be identified correctly by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Typing of anaerobic bacteria on a subspecies level, determination of antibiotic resistance and direct identification of blood culture isolates will revolutionize anaerobe bacteriology in the near future.

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.

Thiazolidinedione derivatives as novel agents against Propionibacterium acnes biofilms

AIMS

The aim of the present study was to determine the effect of two thiazolidinedione derivatives on Propionibacterium acnes biofilm formation in vitro and to assess their effect on the susceptibility of P. acnes biofilms towards antimicrobials.

METHODS AND RESULTS

The compounds were shown to have a moderate to strong antibiofilm activity when used in subinhibitory concentrations. These compounds do not affect P. acnes attachment but lead to increased dispersal of biofilm cells. This dispersal results in an increased killing of the P. acnes biofilm cells by conventional antimicrobials.

CONCLUSION

The antibiofilm effect and the effect on biofilm susceptibility of the thiazolidinedione-derived quorum sensing inhibitors were clearly demonstrated.

SIGNIFICANCE AND IMPACT OF THE STUDY

Propionibacterium acnes infections are difficult to treat due to the presence of biofilms at the infection site and the associated resistance towards conventional antimicrobials. Our results indicate that these thiazolidinedione derivatives can be promising leads used for the treatment of P. acnes infections and as anti-acne drugs.

Osteomyelitis: an overview of antimicrobial therapy

Osteomyelitis is an inflammatory bone disorder caused by infection, leading to necrosis and destruction of bone. It can affect all ages, involve any bone, become a chronic disease and cause persistent morbidity. Treatment of osteomyelitis is challenging particularly when complex multiresistant bacterial biofilm has already been established. Bacteria in biofilm persist in a low metabolic phase, causing persistent infection due to increased resistance to antibiotics. Staphylococcus aureus and Staphylococcus epidermidis are the most common causative organism responsible for more than 50% of osteomyelitis cases. Osteomyelitis treatment implies the administration of high doses of antibiotics (AB) by means of endovenous and oral routes and should take a period of at least 6 weeks. Local drug delivery systems, using non-biodegradable (polymethylmethacrylate) or biodegradable and osteoactive materials such as calcium orthophosphates bone cements, have been shown to be promising alternatives for the treatment of osteomyelitis. These systems allow the local delivery of AB in situ with bactericidal concentrations for long periods of time and without the toxicity associated with other means of administration. This review examines the most recent literature evidence on the causes, pathogeneses and pharmacological treatment of osteomyelitis. The study methodology consisted of a literature review in Google Scholar, Science Direct, Pubmed, Springer link, B-on. Papers from 1979 till present were reviewed and evaluated.

Post-traumatic bone and/or joint limb infections due to Clostridium spp

BACKGROUND

Clostridium spp. are saprophytic Gram-positive bacteria found in soil and capable of generating endospores. Spore germination occurs when environmental conditions are favorable. Clostridium spp. can cause infections of compound fractures and deep wounds contaminated from soil micro-organisms.

HYPOTHESIS

Clostridium spp. infections of traffic-related injuries are particularly severe events whose outcome is uncertain even with aggressive medical and surgical treatment.

MATERIALS AND METHODS

We retrospectively reviewed 12 patients (median age, 45 years) with Clostridium spp. bone and/or joint infections complicating compound limb fractures with soil contamination and extensive soft-tissue damage. Prophylactic amoxicillin-clavulanic acid therapy was administred, followed by emergency surgical wound debridment and lavage. Fracture fixation was performed immediately in nine patients (external in four and internal in five) or at a later time on three patients. The immediate outcome was unfavourable in all 12 cases, requiring early reoperation after a median of 10 days (range, 5-25 days).

RESULTS

Median time to Clostridium strain identification was 14.5 days (range, 5-160). All infections were polymicrobial. Surgical wound excision, hardware removal (in four cases), and antibiotic therapy produced a favourable outcome in one patient, with no recurrence after 2 years of follow-up; the outcome was unfavourable in 11 cases, with delayed fracture union, septic non-union, impaired healing, and/or chronic sinus tract drainage. Several second-line treatments were used in these 11 patients: intramedullary nailing without bone grafting in four patients, with three failures; decortication and grafting in two patients, with failure in both; nailing with decortication in one patient, who had a good outcome; and the induced membrane procedure described by Masquelet in four patients, all of whom had good outcomes. After a median follow-up of 24 months (range, 18-53 months), the bone infection had subsided in eight patients. The remaining four patients had septic non-union.

DISCUSSION

Clostridium spp. infections are particularly severe. The diagnosis is delayed and identification of the organism is challenging. The treatment is difficult and results in unfavorable outcomes in one-third of cases. The identification of Clostridium in specimens from an osteoarticular infection indicates a need for extremely extensive and aggressive surgical resection, as spore resistance may impair the in vivo efficacy of antimicrobial agents.

LEVEL OF EVIDENCE

IV (retrospective cohort study).