The Association between Gut Microbiota and Osteoarthritis: Does the Disease Begin in the Gut?

Some say that all diseases begin in the gut. Interestingly, this concept is actually quite old, since it is attributed to the Ancient Greek physician Hippocrates, who proposed the hypothesis nearly 2500 years ago. The continuous breakthroughs in modern medicine have transformed our classic understanding of the gastrointestinal tract (GIT) and human health. Although the gut microbiota (GMB) has proven to be a core component of human health under standard metabolic conditions, there is now also a strong link connecting the composition and function of the GMB to the development of numerous diseases, especially the ones of musculoskeletal nature. The symbiotic microbes that reside in the gastrointestinal tract are very sensitive to biochemical stimuli and may respond in many different ways depending on the nature of these biological signals. Certain variables such as nutrition and physical modulation can either enhance or disrupt the equilibrium between the various species of gut microbes. In fact, fat-rich diets can cause dysbiosis, which decreases the number of protective bacteria and compromises the integrity of the epithelial barrier in the GIT. Overgrowth of pathogenic microbes then release higher quantities of toxic metabolites into the circulatory system, especially the pro-inflammatory cytokines detected in osteoarthritis (OA), thereby promoting inflammation and the initiation of many disease processes throughout the body. Although many studies link OA with GMB perturbations, further research is still needed.

The Great Masquerader - TB Osteoarthritis

OBJECTIVES

TB arthritis is a rarely reported entity in Western literature and its ability to masquerade as many other diseases makes it difficult to diagnose. We report an interesting case of TB arthritis of the ankle.

METHODS

We present a 44 year-old diabetic Chinese male with a recent history of worsening pain, swelling, and redness in his left foot with an abscess and X-ray findings consistent with Charcot foot.

RESULTS

At first, the presentation was believed to be Charcot's foot with MSSA osteomyelitis but after the wound culture and bone biopsy were both positive for Mycobacterium tuberculosis as well, the diagnosis of tuberculous arthritis was confirmed.

CONCLUSIONS

While the prevalence of TB and other diseases is low in the majority of the United States, we still need to be aware of such diseases in populations with increasing migration and be cognizant of the potential impact of a patient's background on a diagnosis is critical to properly diagnosing and treating patients. Vascular surgeons may be seeing patients with abscesses of the lower extremities and may miss the diagnosis if cultures for TB are not sought.

The causal role of gut microbiota in development of osteoarthritis

OBJECTIVE

There is considerable evidence for relationship between gut microbiota and osteoarthritis (OA), but no studies have investigated their causal relationship.

METHOD

This study utilized large-scale genome-wide association studies (GWAS) summary statistics to evaluate the causal association between gut microbiota and OA risk. Specifically, two-sample Mendelian randomization (MR) approach was used to identify the causal microbial taxa for OA. Comprehensively sensitive analyses were performed to validate the robustness of results and novel multivariable MR analyses were further conducted to ensure the independence of causal association. Reverse-direction MR analyses were performed to rule out the possibility of reverse associations. Finally, enrichment analyses were used to investigate the biofunction.

RESULTS

After correction, three microbial taxa were identified to be causally associated with diverse joint OA (P_FDR < 0.100), namely Methanobacteriaceae family for knee OA (P_FDR = 0.043) and any OA (P_FDR = 0.028), Desulfovibrionales order for knee OA (P_FDR = 0.045) and Ruminiclostridium5 genus for knee OA (P_FDR = 0.063). In addition, we also identified five suggestive microbial taxa that were significant with three different methods under the nominal significance (P < 0.05). Sensitive analysis excluded the influence of heterogeneity and horizontal pleiotropy and multivariable MR analysis ruled out the possibility of horizontal pleiotropy of BMI. GO enrichment analysis illustrates the protective mechanism of the identified taxa against OA.

CONCLUSIONS

This study found that several microbial taxa were causally associated with diverse joint OA. The results enhanced our understanding of gut microbiota in the pathology of OA.

Taxonomic changes in the gut microbiota are associated with cartilage damage independent of adiposity, high fat diet, and joint injury

Lipodystrophic mice are protected from cartilage damage following joint injury. This protection can be reversed by the implantation of a small adipose tissue graft. The purpose of this study was to evaluate the relationship between the gut microbiota and knee cartilage damage while controlling for adiposity, high fat diet, and joint injury using lipodystrophic (LD) mice. LD and littermate control (WT) mice were fed a high fat diet, chow diet, or were rescued with fat implantation, then challenged with destabilization of the medial meniscus surgery to induce osteoarthritis (OA). 16S rRNA sequencing was conducted on feces. MaAslin2 was used to determine associations between taxonomic relative abundance and OA severity. While serum LPS levels between groups were similar, synovial fluid LPS levels were increased in both limbs of HFD WT mice compared to all groups, except for fat transplanted animals. The Bacteroidetes:Firmicutes ratio of the gut microbiota was significantly reduced in HFD and OA-rescued animals when compared to chow. Nine novel significant associations were found between gut microbiota taxa and OA severity. These findings suggest the presence of causal relationships the gut microbiome and cartilage health, independent of diet or adiposity, providing potential therapeutic targets through manipulation of the microbiome.

The microbiome mediates epiphyseal bone loss and metabolomic changes after acute joint trauma in mice

OBJECTIVE

To compare the early responses to joint injury in conventional and germ-free mice.

DESIGN

Post-traumatic osteoarthritis (PTOA) was induced using a non-invasive anterior cruciate ligament rupture model in 20-week old germ-free (GF) and conventional C57BL/6 mice. Injury was induced in the left knees of n = 8 GF and n = 10 conventional mice. To examine the effects of injury, n = 5 GF and n = 9 conventional naïve control mice were used. Mice were euthanized 7 days post-injury, followed by synovial fluid recovery for global metabolomic profiling and analysis of epiphyseal trabecular bone by micro-computed tomography (μCT). Global metabolomic profiling assessed metabolic differences in the joint response to injury between GF and conventional mice. Magnitude of trabecular bone volume loss measured using μCT assessed early OA progression in GF and conventional mice.

RESULTS

μCT found that GF mice had significantly less trabecular bone loss compared to conventional mice, indicating that the GF status was protective against early OA changes in bone structure. Global metabolomic profiling showed that conventional mice had greater variability in their metabolic response to injury, and a more distinct joint metabolome compared to their corresponding controls. Furthermore, differences in the response to injury in GF compared to conventional mice were linked to mouse metabolic pathways that regulate inflammation associated with the innate immune system.

CONCLUSIONS

These results suggest that the gut microbiota promote the development of PTOA during the acute phase following joint trauma possibly through the regulation of the innate immune system.

Osteoarthritis year in review 2020: biology

This year in review about osteoarthritis biology highlights a selection of articles published between the 2019 and 2020 Osteoarthritis Research Society International (OARSI) World Congress meetings, within the field of osteoarthritis biology. Highlights were selected from PubMed searches covering osteoarthritis (OA) cartilage, subchondral bone, synovium and aging. Subsequently, a personal selection was based on new and emerging themes together with common research topics that were studied by multiple groups. Themes discussed include novel insights into the inflammatory changes during OA, with a number of noteworthy publications concerning the role of macrophages in healthy and osteoarthritic joints. Next, the application of mesenchymal stem cells as OA-dampening therapy is discussed, including possible ways to improve their efficacy by pre-treatment. Other significant themes including treatment of OA with metformin, enhancing autophagy to alleviate OA and the involvement of the gastro-intestinal microbiome in development of OA symptoms and structural damage are discussed. An effort was made to connect the seemingly distant topics from which the overarching conclusion can be drawn that over the last year promising breakthroughs have been achieved in further understanding the biology of OA development and that new therapeutic possibilities have been explored.

The Role of Chitosan and Graphene Oxide in Bioactive and Antibacterial Properties of Acrylic Bone Cements

Acrylic bone cements (ABC) are widely used in orthopedics for joint fixation, antibiotic release, and bone defect filling, among others. However, most commercially available ABCs exhibit a lack of bioactivity and are susceptible to infection after implantation. These disadvantages generate long-term loosening of the prosthesis, high morbidity, and prolonged and expensive treatments. Due to the great importance of acrylic bone cements in orthopedics, the scientific community has advanced several efforts to develop bioactive ABCs with antibacterial activity through several strategies, including the use of biodegradable materials such as chitosan (CS) and nanostructures such as graphene oxide (GO), with promising results. This paper reviews several studies reporting advantages in bioactivity and antibacterial properties after incorporating CS and GO in bone cements. Detailed information on the possible mechanisms by which these fillers confer bioactive and antibacterial properties to cements, resulting in formulations with great potential for use in orthopedics, are also a focus in the manuscript. To the best of our knowledge, this is the first systematic review that presents the improvement in biological properties with CS and GO addition in cements that we believe will contribute to the biomedical field.

Gut microbiota and osteoarthritis management: An expert consensus of the European society for clinical and economic aspects of osteoporosis, osteoarthritis and musculoskeletal diseases (ESCEO)

The prevalence of osteoarthritis (OA) increases not only because of longer life expectancy but also because of the modern lifestyle, in particular physical inactivity and diets low in fiber and rich in sugar and saturated fats, which promote chronic low-grade inflammation and obesity. Adverse alterations of the gut microbiota (GMB) composition, called microbial dysbiosis, may favor metabolic syndrome and inflammaging, two important components of OA onset and evolution. Considering the burden of OA and the need to define preventive and therapeutic interventions targeting the modifiable components of OA, an expert working group was convened by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) to review the potential contribution of GMB to OA. Such a contribution is supported by observational or dietary intervention studies in animal models of OA and in humans. In addition, several well-recognized risk factors of OA interact with GMB. Lastly, GMB is a critical determinant of drug metabolism and bioavailability and may influence the response to OA medications. Further research targeting GMB or its metabolites is needed to move the field of OA from symptomatic management to individualized interventions targeting its pathogenesis.

Intraosteoblastic activity of levofloxacin and rifampin alone and in combination against clinical isolates of meticillin-susceptible Staphylococcus aureus causing prosthetic joint infection

BACKGROUND

Staphylococcus aureus may invade and persist intracellularly in prosthetic joint infections (PJIs). Despite optimized treatments with levofloxacin plus rifampin, the intracellular reservoir may lead to infection relapse. This study assessed the intracellular activity of levofloxacin and rifampin in an in-vitro model of human osteoblastic infection.

METHODS

Ten meticillin-susceptible S. aureus strains were used to infect osteoblastic MG63 cells. Osteoblasts were challenged with rifampin and levofloxacin at cortical and cancellous bone concentrations. Efficacy was measured as the intracellular counts of colony-forming units (log₁₀CFU) compared with untreated controls. The emergence of small colony variants (SCVs) was determined, and the results were stratified according to the patient's prognosis (six cured and four with persistence/relapse).

RESULTS

All regimes led to a significant decrease in CFU count compared with controls (1-2 log₁₀CFU). Levofloxacin was the most effective treatment at both cortical and cancellous bone concentrations (-2.4 to -1.9 log₁₀CFU, respectively). The addition of rifampin to levofloxacin did not improve performance (-1.9 log₁₀CFU for cortical concentration and -1.8 log₁₀ CFU for cancellous concentration). An increase in SCVs was observed in the presence of rifampin. The efficacy of antimicrobials was higher and the formation of SCVs was lower against strains belonging to PJIs with a favourable outcome.

CONCLUSIONS

Levofloxacin plus rifampin had good intracellular activity against S. aureus. However, from the intracellular perspective, the addition of rifampin to levofloxacin showed no benefit but could account for an increased number of SCVs.

Validation of a novel molecular diagnostic panel for pediatric musculoskeletal infections: Integration of the Cepheid Xpert MRSA/SA SSTI and laboratory-developed real-time PCR assays for clindamycin resistance genes and Kingella kingae detection

BACKGROUND

Pathogen detection in pediatric patients with musculoskeletal infections relies on conventional bacterial culture, which is slow and can delay antimicrobial optimization. The ability to rapidly identify causative agents and antimicrobial resistance genes in these infections may improve clinical care.

METHODS

Convenience specimens from bone and joint samples submitted for culture to Children's Hospital Colorado (CHCO) from June 2012 to October 2016 were evaluated using a "Musculoskeletal Diagnostic Panel" (MDP) consisting of the Xpert MRSA/SA SSTI real-time PCR (qPCR, Cepheid) and laboratory-developed qPCRs for Kingella kingae detection and erm genes A, B, and C which confer clindamycin resistance. Results from the MDP were compared to culture and antimicrobial susceptibility testing (AST) results.

RESULTS

A total of 184 source specimens from 125 patients were tested. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the Xpert MRSA/SA SSTI compared to culture and AST results were 85%, 98%, 93%, and 95% respectively for MSSA and 82%, 100%, 100%, and 99% for MRSA. Compared to phenotypic clindamycin resistance in S. aureus isolates, the erm A, B, and C gene PCRs collectively demonstrated a sensitivity, specificity, PPV, and NPV of 80%, 96%, 67%, and 98%. In comparison to clinical truth, Kingella PCR had a sensitivity, specificity, PPV, and NPV of 100%, 99.5%, 100%, and 100%.

CONCLUSIONS

This novel MDP offers a rapid, sensitive, and specific option for pathogen detection in pediatric patients with musculoskeletal infections.

Bacteriological relevance of linezolid vs. vancomycin in postoperative empirical treatment of osteoarticular infections: a retrospective single-center study

BACKGROUND

In 2015, our center replaced vancomycin with linezolid for the postoperative empirical treatment of osteoarticular infections (OAI).

OBJECTIVES

To assess the bacteriological relevance of linezolid for orthopedic postoperative probabilistic antibiotic therapy.

METHODS

Analysis of an observational cohort of patients empirically treated with a combination of linezolid and piperacillin/tazobactam during the immediate postoperative stage for an OAI between July 1^st 2015 and July 1^st 2016, in a French reference center.

RESULTS

Seventy-seven of 126 patients who received a probabilistic postoperative combination of linezolid with piperacillin/tazobactam had microbiological proof of infection. Sixty-six of 77 OAI involved material, including an osteosynthesis in 45 cases (68%) and prosthesis in 21 cases (32%). Infection was due to Gram-positive bacteria in 62 cases (80.5%), mostly S. aureus (n=32, 41.6%), and S. epidermidis (n=14, 18.2%) accounting for 74.2% of Gram-positive bacteria. Among 14 OAI due to S. epidermidis, 11 (78.6%) were due to methicillin-resistant strains. All the S. aureus and S. epidermidis strains were susceptible to linezolid (MICs ≤ 4 mg/L), except in one patient previously treated with linezolid who was infected with a linezolid-resistant S. epidermidis strain (MIC > 256 mg/L).

CONCLUSION

Linezolid can be used empirically in postoperative antibiotic therapy of OAI before obtaining definitive microbial results. Although linezolid resistance is rare in this population, previous oxazolidinone treatment should be documented before initiation of probabilistic postoperative treatment to highlight potential linezolid resistance.

Characterization of Staphylococcus caprae Clinical Isolates Involved in Human Bone and Joint Infections, Compared with Goat Mastitis Isolates

Staphylococcus caprae is an emerging microorganism in human bone and joint infections (BJI). The aim of this study is to describe the features of S. caprae isolates involved in BJI (H for human) compared with those of isolates recovered in goat mastitis (A for animal). Fourteen isolates of each origin were included. Identifications were performed using a Vitek 2 GP ID card, tuf gene sequencing, and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) Vitek MS. Molecular typing was carried out using pulsed-field gel electrophoresis (PFGE) and DiversiLab technology. The crystal violet method was used to determine biofilm-forming ability. Virulence factors were searched by PCR. Vitek MS technology provides an accurate identification for the two types of isolates compared to that of gold-standard sequencing (sensitivity, 96.4%), whereas the Vitek 2 GP ID card was more effective for H isolates. Molecular typing methods revealed two distinct lineages corresponding to the origin despite few overlaps: H and A. In our experimental conditions, no significant difference was observed in biofilm production ability between H and A isolates. Nine isolates (5 H isolates and 4 A isolates) behaved as weak producers while one A isolate was a strong producer. Concerning virulence factors, the autolysin atlC and the serine aspartate adhesin (sdrZ) genes were detected in 24 isolates (86%), whereas the lipase gene was always detected, except in one H isolate (96%). The ica operon was present in 23 isolates (82%). Fibrinogen-binding (fbe) or collagen-binding (cna) genes were not detected by using primers designed for Staphylococcus aureus or Staphylococcus epidermidis, even in low stringency conditions. Although S. caprae probably remains underestimated in human infections, further studies are needed to better understand the evolution and the adaptation of this species to its host.

Clinical and epidemiological characteristics of septic arthritis of the hip, 2006 to 2012, a seven-year review

OBJECTIVE

To epidemiologically characterize the population treated at our orthopedic clinic with a diagnosis of septic arthritic of the hip between 2006 and 2012.

METHODS

Fifteen patients diagnosed with septic arthritis of the hip between 2006 and 2012 were retrospectively evaluated. The patients' clinical and epidemiological characteristics were surveyed; a sensitivity profile relating to the microorganisms that caused the infections and the complications relating to the patients' treatment and evolution were identified.

RESULTS

Septic arthritis was more common among males. Most diagnoses were made through positive synovial fluid cultures, after joint drainage was performed using the Smith-Petersen route. Among the comorbidities found, the most prevalent were systemic arterial hypertension, diabetes mellitus, and human immunodeficiency virus. The pathological joint conditions diagnosed prior to joint infection were osteoarthrosis and developmental dysplasia of the hip. The infectious agent most frequently isolated was Staphylococcus aureus. From the clinical and laboratory data investigated, 53.33% of the cases presented with fever, and all except one patient presented with increased measures in inflammation tests. Gram staining was positive in only 26.66% of the synovial fluid samples analyzed. Six patients presented with joint complications after treatment was administered.

CONCLUSION

S. aureus is the most common pathogen in acute infections of the hip in our setting. Factors such as clinical comorbidities are associated with septic arthritis of the hip. Because of the relatively small number of patients, given that this is a condition of low prevalence, there was no statistically significant correlation in relation to worse prognosis for the disease.

Clinical characteristics, microbiology, and outcomes of prosthetic joint infection in Taiwan

BACKGROUND

Prosthetic joint infection (PJI) after total knee or hip replacement is a devastating complication associated with substantial morbidity and economic cost. The incidence of prosthetic joint infection is increasing as the use of mechanical joint replacement increases. The treatment approach to prosthetic joint infection is based on different clinical situations such as a patient's comorbidities, epidemic microbiology data, and surgical procedures. The aim of our study was to understand clinical characteristics of prosthetic joint infection, the microbiology of the prosthetic joint infection, and the outcomes of different treatment strategies during 2006-2011.

METHODS

We retrospectively collected cases of prosthetic joint infection in the National Taiwan University Hospital between January 1, 2006 and December 31, 2011. The patients' characteristics, microbiology, outcomes, and factors associated with treatment success were recorded.

RESULTS

One hundred and forty-four patients were identified as having PJI. Of these, 92 patients were entered into per-protocol analysis. Staphylococcus aureus was the most common causative organism (29.9%), followed by coagulase-negative Staphylococci (16.7%), and Enterococci (9.7%). The overall treatment success rate was 50%. Patients who received a two-stage revision had a better outcome, compared to patients who underwent other types of surgeries (70% vs. 32.7%, respectively; p < 0.001). In multivariate analysis, the two-stage revision was significantly associated with treatment success (odds ratio = 3.923, 95% confidence interval = 1.53-10.04).

CONCLUSION

Our study demonstrates that Staphylococcus aureus was the most common causative organisms in PJI. Performing two-stage revisions was significantly associated with a better outcome.

Characteristics and outcome of 16 periprosthetic shoulder joint infections

PURPOSE

Shoulder arthroplasties are increasingly performed, but data on periprosthetic joint infections (PJI) in this anatomical position are limited. We retrospectively investigated the characteristics and outcome of shoulder PJI after primary arthroplasty from 1998 to 2010 in a single centre.

METHODS

Periprosthetic joint infection was defined as periprosthetic purulence, presence of sinus tract or microbial growth. A Kaplan-Meier survival method was used to estimate relapse-free survival of prosthesis.

RESULTS

From 1,571 primary shoulder prostheses, we evaluated 16 patients with a PJI at different stages, i.e, early (n = 4), delayed (n = 6) and late (n = 6) infections. The median patient age was 67 (range 53-86) years, and 69 % were females. The most commonly isolated microorganism was Propionibacterium acnes in 38 % of patients (monobacterial in four and polymicrobial in two patients). In 14 of the 16 patients, surgical interventions consisting of debridement and implant retention (6 patients), exchange (7) and explantation (1) were performed. Four patients had a relapse of infection with P. acnes (n = 3) or Bacteroides fragilis (n = 1). The relapse-free survival of the prosthesis was 75 % (95 % confidence interval 46-90 %) after 1 and 2 years, 100 % in six patients following the treatment algorithm for hip and knee PJI and 60 % in 10 patients not followed up. All but one of the relapses were previously treated without exchange of the prosthesis.

CONCLUSIONS

As recommended for hip and knee PJI, we suggest treating shoulder PJI with a low-grade infection by microorganisms such as P. acnes with an exchange of the prosthesis. Cohort studies are needed to verify our results.

Osteoarticular infection by Candida albicans in an infant with cystic fibrosis

Invasive candidiasis is rare in children after the neonatal period, but can occur in children with (secondary) immunodeficiency with a damaged gastrointestinal or skin barrier, or when receiving antibiotics. A 10-month-old girl was diagnosed as suffering from cystic fibrosis (CF) when showing failure to thrive, pulmonary symptoms and hypoproteinaemia. At that time, Candida albicans was identified from blood culture and treated intravenously with liposomal amphotericin B for 13 days. Six weeks later, the girl presented with osteoarticular infection of the left knee caused by C. albicans. The infection showed insufficient response to therapy with liposomal amphotericin B, but the patient recovered after therapy with fluconazole and flucytosine. Follow-up over 4 years revealed no sequelae. In conclusion, invasive Candida infections may occur in patients with CF, and preventive measures might be considered in patients at risk. In the case of an invasive infection, prolonged treatment with a combination of antifungal drugs may be required.

Clinical features of group B Streptococcus prosthetic joint infections and molecular characterization of isolates

Twelve group B Streptococcus (GBS) prosthetic joint infection (PJI) cases are reported. The mean patient age was 55 years. Eleven infections were caused by GBS alone. The associated isolates belonged to phylogenetic lineages different from those that cause neonatal meningitis. The clinical outcome was favorable for the eight patients for whom follow-up data were available.

Osteoarthritis in the neonate: risk factors and outcome

OBJECTIVES

The aim of this study was to identify the clinical, radiological, and bacteriological features, risk factors, and outcome of neonates with bone and joint infections.

STUDY DESIGN

Observational, retrospective, and analytical study of 77 patients less than 2 months of age, admitted to a tertiary neonatal intensive care unit (NICU) with the diagnosis of bone or joint infection, based on clinical, radiological, and microbiological criteria.

RESULTS

Seventy-seven patients with 99 acute osteoarthritis foci in a 16 year period were included in the study. Risk factors for infection could be identified in 69% of the patients. The hip was the most frequent. Staphylococcus aureus was the main isolated microorganism. Twenty-nine infants (38%) had sequelae. Hip involvement, culture positive, and Staphylococcus aureus isolation were risk factors associated with sequelae.

CONCLUSION

Osteoarticular infection is unusual in the neonate; however it is associated with an elevated incidence of sequelae. This mandates for a high degree of suspicion to diagnose this potentially disabling entity.

[Tarsal osteoarthritis: a rare localisation of tuberculosis]

We report the case of a 39-year-old woman with an uneventful medical history who presented an inflammatory left foot with no notion of trauma or fever. The plain x-ray and magnetic resonance imaging demonstrated talonavicular and subtalar osteoarthritis. A surgical biopsy with excision of inflammatory and necrotic tissue and removal of a fistular tract was performed. Histology revealed the presence of granulomas with caseous central necrosis suggesting tuberculosis of the bone. The diagnosis was confirmed when bacteriology samples grew Mycobacterium tuberculosis. Antituberculosis drugs were administered for twelve months. At 24 months, the patient presents a painful stiff rear foot after the development of secondary talonavicular degeneration. This case illustrates a particular clinical presentation of tuberculosis. This diagnosis should be considered in the presence of atypical bony lesions with a chronic course. Early diagnosis enables proper therapeutic management. Useful diagnostic imaging techniques include plain x-rays, computed tomography, and magnetic resonance imaging. Certain diagnosis is based on bacteriological and histological examinations.

Induction of multiple matrix metalloproteinases in human dermal and synovial fibroblasts by Staphylococcus aureus: implications in the pathogenesis of septic arthritis and other soft tissue infections

Infections of body tissue by Staphylococcus aureus are quickly followed by degradation of connective tissue. Patients with rheumatoid arthritis are more prone to S. aureus-mediated septic arthritis. Various types of collagen form the major structural matrix of different connective tissues of the body. These different collagens are degraded by specific matrix metalloproteinases (MMPs) produced by fibroblasts, other connective tissue cells, and inflammatory cells that are induced by interleukin-1 (IL-1) and tumor necrosis factor (TNF). To determine the host's contribution in the joint destruction of S. aureus-mediated septic arthritis, we analyzed the MMP expression profile in human dermal and synovial fibroblasts upon exposure to culture supernatant and whole cell lysates of S. aureus. Human dermal and synovial fibroblasts treated with cell lysate and filtered culture supernatants had significantly enhanced expression of MMP-1, MMP-2, MMP-3, MMP-7, MMP-10, and MMP-11 compared with the untreated controls (p < 0.05). In the S. aureus culture supernatant, the MMP induction activity was identified to be within the molecular-weight range of 30 to >50 kDa. The MMP expression profile was similar in fibroblasts exposed to a combination of IL-1/TNF. mRNA levels of several genes of the mitogen-activated protein kinase (MAPK) signal transduction pathway were significantly elevated in fibroblasts treated with S. aureus cell lysate and culture supernatant. Also, tyrosine phosphorylation was significantly higher in fibroblasts treated with S. aureus components. Tyrosine phosphorylation and MAPK gene expression patterns were similar in fibroblasts treated with a combination of IL-1/TNF and S. aureus. Mutants lacking staphylococcal accessory regulator (Sar) and accessory gene regulator (Agr), which cause significantly less severe septic arthritis in murine models, were able to induce expression of several MMP mRNA comparable with that of their isogenic parent strain but induced notably higher levels of tissue inhibitors of metalloproteinases (TIMPs). To our knowledge, this is the first report of induction of multiple MMP/TIMP expression from human dermal and synovial fibroblasts upon S. aureus treatment. We propose that host-derived MMPs contribute to the progressive joint destruction observed in S. aureus-mediated septic arthritis.

Detection of DNA from a range of bacterial species in the knee joints of dogs with inflammatory knee arthritis and associated degenerative anterior cruciate ligament rupture

Mixtures of bacterial nucleic acids can often be detected in synovial joints affected with arthritis. We investigated the potential role of such mixtures of bacterial nucleic acids in the pathogenesis of arthritis in a naturally occurring canine model. Dogs with a common inflammatory knee arthritis in which associated pathological degenerative anterior cruciate ligament (ACL) rupture often develops were studied. Synovial biopsies were obtained from 43 dogs with the naturally occurring ACL rupture arthropathy, 12 dogs with normal knees and intact ACL, and 16 dogs with normal knees and experimentally induced ACL rupture. Using PCR, specimens were tested for Borrelia burgdorferi OspA and p66 gene sequences. Broad-ranging 16S rRNA primers were also used; 'panbacterial' PCR products were cloned and multiple clones were sequenced for bacterial identification. Synovium was also studied histologically. The presence of bacterial DNA within the synovium was significantly associated with the naturally occurring ACL rupture arthropathy (p<0.05); knee joints from 37% of these dogs were PCR-positive. Mixtures of bacterial DNA were common and often included environmental bacteria; predominant organisms included Borrelia burgdorferi and Stenotrophomonas maltophilia. DNA from environmental bacteria was only found in dogs with the naturally occurring ACL rupture arthopathy; joints from 33% of affected dogs contained such bacterial DNA. Synovial inflammation developed in dogs with both naturally occurring and experimentally induced ACL rupture, when compared with intact ACL controls (p<0.01). These results indicate that mixtures of DNA derived from environmental bacteria are commonly found in the knee joint of a naturally occurring canine arthropathy, often in association with a recognized joint pathogen. Our results also suggest that knee instability alone is not responsible for this finding and have led us to hypothesize that mixtures of bacterial DNA are an important causative factor in the pathogenesis of inflammatory arthritis in this canine model.

Is osteoarthritis an infection-associated disease and a target for chemotherapy?

The treatment of osteoarthritis (OA) continues to be a challenge, and current treatment modalities are disappointing. New approaches in therapy may be developed as a result of evidence of the involvement of inflammatory cytokines in the progression of OA. Cotrimoxazole (sulfamethoxazole/trimethoprim) was noted to have anti-inflammatory properties and has been used in the therapy of several autoimmune diseases. Analyzing our own and world experience, we propose that OA and degenerative joint and spine disease might be infection-associated diseases and a target for sulfamethoxazole/trimethoprim therapy.

Distribution of Mycoplasma pneumoniae and Mycoplasma salivarium in the synovial fluid of arthritis patients

By use of a very sensitive nested PCR method targeting part of the strongly conserved mycoplasmal 16S RNA genes, Mycoplasma pneumoniae was found in the synovial fluid of 19/24 (79%) of rheumatoid arthritis patients, 6/6 (100%) of patients with nonrheumatoid inflammatory arthritis, and 8/10 (80%) of osteoarthritis patients attending the rheumatology clinic for drainage of joint effusions. It was not found in the synovial exudates of 13 people attending the orthopedic clinic with traumatic knee injuries or undergoing surgery for knee replacement. However, M. pneumoniae was detected in 2/4 synovial biopsy specimens from orthopedic patients with traumatic knee injuries. M. pneumoniae was associated with the increased synovial fluids found in arthritic flares but was not found in the synovial fluids of trauma patients. Mycoplasma salivarium occurred sporadically. Mycoplasma fermentans had previously been isolated from patients with inflammatory cellular infiltrates, such as rheumatoid arthritis, but it was not detected for osteoarthritic patients from either clinic. It is possible that these organisms may contribute to chronic inflammation within the joints.

Synovial inflammation in active rheumatoid arthritis and psoriatic arthritis facilitates trapping of a variety of oral bacterial DNAs

OBJECTIVE

To investigate the presence of oral bacterial DNAs in serum and synovial fluid (SF) of patients with active rheumatoid arthritis (RA) and psoriatic arthritis (PsA).

METHODS

Serum and SF samples from 16 RA patients, 14 PsA patients, and 9 osteoarthritis (controls) patients were extracted for oral bacterial DNA. This was used in a checkerboard DNA-DNA-hybridization set up, to identify 40 different bacteria.

RESULTS

Mean number +/- standard deviation (SD) of oral bacterial species in sera were 6.2 (3.2) in the RA group (p = 0.004) and 5.4 (2.7) in the PsA group (p = 0.009) compared to 2.1 (1.7) in the controls. Periodontitis associated species Porphyromonas gingivalis and Prevotella nigrescens were exclusively detected in RA and PsA. Mean number (+/- SD) of oral bacterial species in SF were 14.0 (6.8) in the RA (p = 0.001) and 19.4 (7.1) in the PsA group (p < 0.001) compared to 4.0 (1.7) in controls. P. gingivalis, Tannerella forsythensis and Prevotella intermedia were exclusively identified in RA and PsA SF. Higher means of DNAs were found in RA SF compared to RA serum (p < 0.001), and in PsA SF compared to PsA serum (p < 0.001). Higher concentrations of bacterial DNAs were found in RA and PsA compared to controls.

CONCLUSION

Higher variety and concentrations of oral bacterial DNAs were found in SF compared to serum of RA and PsA patients. These findings indicate that synovial inflammation in RA and PsA may favor trapping of oral bacterial DNAs, suggesting a perpetuating effect of oral pathogens in joint disease.

Severe osteoarticular infection associated with Panton-Valentine leukocidin-producing Staphylococcus aureus

We report here a case of osteoarticular infection associated with Panton-Valentine leukocidin-producing Staphylococcus aureus. The 3-year-old child presented osteoarthritis associated with toxic shock syndrome, which was complicated by thrombosis, pneumonia, and diaphysitis, despite appropriate antibiotic treatment. Osteitis associated with toxinogenic S. aureus is rarely described. This case highlights the need of early and aggressive surgical treatment, in addition to appropriate antimicrobial therapy.

Nontyphoidal Salmonella causing focal infections in patients admitted at a Spanish general hospital during an 11-year period (1991–2001)

In focal infections (FI) caused by nontyphoidal Salmonella serotypes and recorded at a Spanish hospital 1991-2001, clinical and microbiological features were analyzed. Thirty-five revised episodes were related to infections of the digestive (10), urinary (10), pulmonar (4), vascular (4), osteoarticular (3) and central nervous (3) systems, and with a submaxillary lymph node. At least 16 episodes were associated with previous or concomitant gastroenteritis, 19 with primary or secondary bacteremia, and 18 with underlying diseases of different severity. Eighteen patients were male and 14 female (data were not available for three patients), while 1, 4, 12 and 15 patients were, respectively, categorized as children, young adults, senior adults and elderly. Sources of Salmonella strains were urine (13), blood (11), purulent abscess (8), cerebrospinal fluid (3), peritoneal fluid, pleural fluid, wound exudates, aneurism (2 of each), ascitic fluid, sputum, tracheal aspirate, needle aspirate, bone and lymph node (1 of each) samples. Only 28 Salmonella strains involved in FIs were available for further analysis. They were discriminated into 6 serotypes, and into 13 XbaI macrorestriction, 6 virulence, 11 antimicrobial resistance, 5 integron and 10 plasmid profiles. Broadly, the pattern of serotype distribution of salmonellas involved in FIs matched that of those causing gastroenteritis, with the pandemic Enteritidis and Typhimurium (18 and 6 strains, respectively) being clearly predominant. Within serotype, the same lineages (as revealed by XbaI-macrorestriction analysis as well as R- and V-profiles) were represented in both disease groups, with host-related factors apparently playing a more critical role than the individual strain in the outcome of the disease.

[Preliminary data concerning cross-reacting anticardiolipin antibodies as potential inhibiting endotoxin activity factors]

In analyzed synovial fluids, suspected for endotoxin presence, the presence of endotoxin done was proved by LAL-test in 21 synovial fluids /42%/ and in 12 of 20 /60%/ the presence of endotoxin inhibiting substances /IS/ was proved. Because many parameters /like presence CIC, anti-LPS, KDO/ indicates that in the group of LAL-negative /IS/ - positive synovial fluids the presence of endotoxin is very possible, IS have been removed /by heating to 100 degrees C/ and after that the endotoxin activity was shown in about 27% of synovial fluids. Additional analysis of the Cohn fraction /prepared by ammonium sulfate precipitation/ confirmed the presence in the gamma and alpha and beta fractions a weak IS activity /in a dose dependent manner. No IS activity, have been shown yet in the fraction of affinity purified aCl antibodies.

Sporothrix schenckii type 3D (mtDNA-RFLP): Report of an osteoarticular case

Sporotrichosis is a frequent subcutaneous mycosis in Mexico and lymphocutaneous cases are the most common type. Extracutaneous or disseminated forms are exceptional and are usually seen in immunosuppressed hosts. We report the case of a 74-year-old immunocompetent male with osteoarticular involvement. The isolated Sporothrix schenckii was classified as type 3D according to restriction fragment length polymorphism analysis of the mitochondrial DNA (mtDNA-RFLP).

[Tuberculous osteoarthritis of the foot in the diabetic: not unrecognize this diagnostic trap. About one case]

Osteoarticular tuberculosis is the fourth leading extrapulmonary localization of tuberculosis. The disease has a progressive course and is often diagnosed in the stage of bone destruction, causing an important diagnostic problem in diabetics with nervous osteoarthropathy. We report the case of a 23-year-old patient with multicomplicated diabetes type 1, treated for pulmonary tuberculosis who consulted after a trauma distended the left ankle. Bone biopsy was performed because of the diagnostic doubt between diabetes and infectious osteoarthropathy. Pathology reported active tuberculosis. Osteoarticular tuberculosis is still a severe disease because of the functional prognosis that requires early diagnosis, a difficult task in some conditions particularly in the diabetic where the disease may mimic nervous osteoarthropathy. Bone biopsy should be performed if there is a doubt.

Sporothrix schenckii infection presented as monoarthritis: report of two cases and review of the literature

Septic arthritis demands early diagnosis and correct treatment if the function of the joint is to be restored. Sometimes, as in fungal infection, signs and symptoms may be mild and the diagnosis delayed. Nevertheless, the outcome of fungal arthritis is severe and usually causes joint disability. The authors report two patients with chronic monoarthritis due to Sporothrix schenckii infection diagnosed by synovial fluid cultures. Their clinical presentation, laboratory and image findings, and their treatment and follow-up are analyzed and compared to previously reported cases. These cases illustrate the differential diagnosis of monoarthritis in immunocompetent adults and picture clinical features that could lead to early diagnosis and proper treatment.

Bacterial aetiology of acute osteoarticular infections in children

AIM

To study the bacterial aetiology of acute osteoarticular infections in children and to analyse the efficiency of culture methods.

METHODS

Bacteriological data of 407 cases of clinically suspected osteoarticular infections affecting 406 children hospitalized in an orthopaedic surgery department between 1999 and 2002 were retrospectively reviewed.

RESULTS

Bacterial cultures from clinical specimens were positive in 74 cases (18%): 38 cases of septic arthritis and 36 cases of bone infections (osteitis, osteomyelitis or osteoarthritis). The use of liquid medium bottles to grow bacteria from articular fluids increased the rate of positive cultures compared to the use of standard solid media (p = 0.0001). The most commonly recovered pathogen was Staphylococcus aureus (44%) followed by Kingella kingae (14%), Streptococcus pyogenes (10%) and Streptococcus pneumoniae (10%). K. kingae was most frequently isolated among children under 36 mo of age (p = 0.0003), whereas S. aureus was most frequently isolated among children over 36 mo (p = 0.0015).

CONCLUSION

By improving our culture method, we observed a recrudescence of isolation of K. kingae, but S. aureus remains the main pathogen isolated from osteoarticular infections in children. This finding is useful for the adaptation of a probabilistic antibiotic treatment of these infections.

Clonal relationship of recent invasive Haemophilus influenzae serotype f isolates from Denmark and the United States

Surveillance performed after the introduction of general Haemophilus influenzae serotype b (Hib) vaccination in Denmark identified 13 cases of invasive bacteraemic H. influenzae serotype f (Hif) disease in adults over a period of 7 years. Bacteraemic respiratory tract infections accounted for 61 % of cases, but meningitis, epiglottitis and osteoarthritis were also seen. Recent Danish isolates were compared to recent American isolates, historical Hif strains and non-Hif invasive strains. Results of conventional serotyping were confirmed by PCR detection of the serotype-f-specific cap and bexA gene sequences. Multilocus enzyme electrophoresis typing revealed that recent Danish and American isolates belonged to a single Hif clone, which may be undergoing expansion. The need for accurate serotyping of H. influenzae to enable reliable monitoring for Hib replacement by other capsular types is emphasized.

Osteoarticular mycobacterial infections in patients with the human immunodeficiency virus

OBJECTIVE

Data about the characteristics of patients with the human immunodeficiency virus (HIV) and concomitant mycobacterial skeletal infection are scarce. Thus, our aim was to describe this condition in a cohort of 11 patients.

METHODS

A review of the records of 11 HIV-positive individuals with microbiological confirmation of mycobacterial osteoarticular infection was conducted. The studied data included: age, sex, risk factor for the HIV days between the onset of symptoms and diagnosis, evidence of previous tuberculosis, location of the infection, isolated organism, diagnostic method, laboratory data (erythrocyte sedimentation rate, haemoglobin, leukocyte count), number of CD4+ lymphocytes, anti-retroviral therapy, treatment and outcome.

RESULTS

Eight patients were men and 3 were women. The median age was 34.2 years (range 20-46 years). Previous tuberculosis was present in 5 cases. Mean days between the onset of symptoms and diagnosis was 124 (range 20-365 days). Infections involved the knee (4 cases), spine (3 cases), hip (2 cases), elbow (1 case) and tibia (1 case). ESR was frequently elevated. The CD4 count ranged from 0.03 to 0.779 x 10(9)/l (mean 0.245 x 10(9)/l). M. tuberculosis was the responsible organism in 9 cases, Mycobacerium tuberculosis plus Staphylococcus aureus in one case and M. Kansasii in one case. Patients received specific treatments with good results. Surgery was necessary in 4 cases. No deaths occurred. Four patients were anti-retroviral naive at the moment the diagnosis was made. The remainder 8 were on zidovudine therapy.

CONCLUSION

The immunologic status of patients with HIV and concomitant mycobacterial skeletal infections is quite variable. The outcome of this condition seems to be good.

Osteoarticular involvement of brucellosis and HLA-B27 antigen frequency in Turkish patients

The aim of the present study is to investigate a possible association between osteoarticular involvement of brucellosis and HLA-B27 antigen. Standard microtoxicity technique method was used for detection of HLA-B27 antigen in 78 patients with brucellosis and 100 healthy donors. Osteoarticular complications were defined in 25 of 78 patients (32.1%). Overall frequency of HLA-B27 in the study group was 14.1% (11/78) and 16% (4/25) in patients with osteoarticular involvement, while it was 8% (8/100) in the control group. Although HLA-B27 frequency in osteoarticular group was slightly higher than both of the other two groups, there was no significant difference (p > 0.05). Conclusively, we could say that further studies including a larger number of patients with osteoarticular involvement of brucellosis may need to be performed in order to find a possible association.

Mycobacterium chelonae osteoarthritis in a Kemp's ridley sea turtle (Lepidochelys kempii)

A stranded Kemp's ridley sea turtle (Lepidochelys kempii) was rescued and treated at the National Aquarium in Baltimore (Maryland, USA) for inappetence and epidermal appendicular and plastral lesions. After 4 mo of care, the turtle developed a swollen left elbow joint. Within 1 mo of initial swelling, osteolytic lesions developed in the proximal radius and ulna. The elbow joint was surgically debrided, flushed, and cultured. The incision dehisced 10 days after surgery. Mycobacterium chelonae was cultured from the left elbow joint and from a skin nodule of the dorsum of the right front flipper. The turtle was euthanized due to apparent systemic infection with M. chelonae. Mycobacterium chelonae was isolated from cultures taken at necropsy of the lung, liver, spleen, kidney, and pericardium. Osteoarthritic infections with M. chelonae have not been reported in reptiles. Additionally, primary osteoarthritic diseases of synovial joints are uncommon in reptilian species. Due to the paucity of reports of mycobacterial diseases in sea turtles, the continued documentation of these cases will increase knowledge and understanding in caring for these endangered animals.

A swollen joint: why all the fuss?

Acute arthritis may be a potential medical emergency. An infected joint causes rapid cartilaginous destruction and risk of future osteoarthritis. Prompt attention to the historical clues and potential causative organisms ensures appropriate therapy. Numerous microbes have been identified as the causative agent in septic arthritis, and various populations have distinct susceptibilities to these specific organisms. One broad classification of septic arthritis is differentiating gonococcal and nongonococcal organisms. This classification is important, as not only do the organisms differ, but the age of the patient and the portal of entry also differ. Aspiration of synovial fluid is paramount for proper diagnosis and management of septic arthritis. In addition, the timely administration of properly chosen antibiotic agents is essential for reducing morbidity and mortality.

HLA-B*39 allele confers susceptibility to osteoarticular complications in human brucellosis

OBJECTIVE

To determine the contribution of HLA gene polymorphism toward susceptibility to osteoarticular focal forms of human brucellosis.

METHODS

A total of 57 patients with brucellosis, of whom 23 had osteoarticular complications, and 73 healthy volunteers were genotyped for HLA class I and class II antigens by a polymerase chain reaction-sequence specific primer technique.

RESULTS

The HLA-B*39 allele was present in significantly more patients with osteoarticular complications than in the other patients (35% vs 3%; p = 0.0006, OR 15.684, 95% CI 3.453-71.231), or in the controls.

CONCLUSION

The increased presence of the HLA-B39 genotype in patients with brucellosis with clinical osteoarticular manifestations suggests that this genotype confers susceptibility to developing severe osteoarticular focal forms of the disease.

Detection of anti-Proteus antibodies in sera of patients with rheumatoid arthritis

This study was carried out to determine increased level of antibodies to certain bacteria in rheumatoid arthritis (RA) patients. Fifty RA patients and 25 each of those suffering from osteoarthritis (OA) and healthy controls were tested for antibodies to somatic ('O) and flagellar ('H') antigens of Proteus mirabilis, Escherichia coli, and for antibodies to 'O' antigen of Klebsiella pneumoniae by standard tube agglutination method. Anti-Proteus antibodies against 'O' and 'H' antigens could be demonstrated in 70% and 64% RA cases respectively, and were statistically significant. Antibodies could be demonstrated against E. coli 'O' and 'H' antigens in 86% and 92% RA cases respectively, and were statistically significant. Against K. pneumoniae 'O' antigen, no antibody could be demonstrated in any of RA and OA cases, and healthy controls. Of the 50 RA patients, 30 had raised CRP levels. Antibodies against P. mirabilis and E. coli antigens appeared to be independent from CRP. Thus a specific elevation in the immune response to P. mirabilis and E. coli has been demonstrated in patients with RA from India.

[Imaging of osteoarticular tuberculosis]

PURPOSE

and methods. To perform an illustrated and educational review of musculoskeletal tuberculosis.

RESULTS

As the incidence of musculoskeletal tuberculosis still increases, a review appears justified. The following four main presentations are detailed and illustrated, by emphasizing the value of both CT and MR imaging: a) spine tuberculosis (~ 50%) commonly involves two adjacent vertebral bodies with usual large paravertebral abscesses. The following lesions are highly suggestive of tuberculosis: solitary vertebral involvement, solitary epidural abscess with or without erosive spondylitis; b) osteo-arthritis: peripherally located erosions at synovial insertions with gradual narrowing of the joint space are highly suggestive; c) osteomyelitis: unusual, may involve any bones; d) tenosynovitis and bursitis.

CONCLUSION

Imaging studies are essential for diagnosis and to assess the extent of musculo-skeletal tuberculosis.

The prevalence of Mycoplasma fermentans in patients with inflammatory arthritides

OBJECTIVES

To search for evidence that Mycoplasma fermentans is involved in the pathogenesis of some forms of human arthritis by testing for the presence of mycoplasmal DNA in joint material.

METHODS

M. fermentans DNA was detected by the identification of a 104-base pair amplification product of the polymerase chain reaction (PCR).

RESULTS

M. fermentans DNA was detected in synovial fluid samples from six (17%) of 35 patients with rheumatoid arthritis (RA) and 18 (21%) of 85 patients with seronegative arthritis. These detection rates were significantly greater than in samples from patients with osteoarthritis or crystal synovitis, none of 26 of these being positive.

CONCLUSIONS

M. fermentans could be involved in the pathogenesis of some forms of inflammatory arthritis and this possibility is worthy of further study.

Expression of natural peptide antibiotics in human articular cartilage and synovial membrane

In view of frequent present use of invasive procedures on limb joints, it is astonishing that articular joint inflammation is a rare event. We questioned whether antimicrobial peptides play a role in protecting human articular cartilage and synovial membrane against inflammatory agents. Our results implicate defensins in the protection of human articular joints against pathogens.

Effect of intra-articular administration of hyaluronan and cortisone on secondary osteoarthritis of the infected rabbit's knee

Hyaluronan is known to play an important role in the healing of degenerative osteoarthritis. But there is no clear consensus how it effects on osteoarthritis compare to cortisone. The purpose of the research was to determine the comparative effects of hyaluronan and cortisone on the healing of degenerative osteoarthritis. A rabbit model used in which a degenerative osteoarthritis were created in the articular cartilage by the inoculation of Staphylococcus Aureus (S. Aureus). The rabbits divided into two groups namely injected with hyaluronan (group A) and cortisone (group B) at days 20, 23 and 26. After hyaluronan and cortisone injections for treatment of osteoarthritis at day of 25 and 35 six rabbits (each of three injected with hyaluronan and cortisone) and at day 50 (six of injected with hyaluronan and five of cortisone) were sacrified. In biopsies obtained from these knees both articular cartilage degeneration and inflammation around the joint were examined by light microscopy. It was seen that the histopathologic findings were consistent with active chronic inflammation at day 10, followed by chronic inflammation. At day 5 of treatment the degeneration decreased (60%) in group A, and clinical findings disappeared after day 9 of treatment. At day 15 of hyaluronan treatment the degeneration degree regressed and at day 30 absolutely healed (all except one). In group B, at day 5 of treatment, the clinical findings disappeared and the healing rate was 72%. At day 15 of cortisone treatment, the degeneration slightly increased and at day 30 the degeneration degree increased more than that day of 15. The results showed that cortisone is effective in the treatment of cartilage degeneration and inflammation early in the course of the septic arthritis whereas the therapeutic effect of hyaluronan is higher late in the course of the disease. Further studies are required in order to understand the effectiveness of the combined or consecutive use of these drugs in degenerative osteoarthritis.

A 4-year study of the mycological aspects of Kashin-Beck disease in Tibet

In order to clarify the association between mycotoxin-producing fungi in food and Kashin-Beck disease (KBD), we examined the occurrence and contamination levels of fungi in samples of barley grain, from KBD-affected families and from unaffected families in endemic areas. A control area without the occurrence of KBD served as reference. The first results obtained in 1995 showed that total mesophilic fungal contamination of barley grain was consistently higher in families with KBD. Trichothecium roseum (Pers) Link ex gray, Dreschlera Ito and Alternaria Nees ex Fr. were the three most common fungi significantly associated with KBD. In 1996 we again observed a significant difference between affected and non-affected families, especially with Trichothecium roseum and Ulocladium Preuss. On this basis, measures to prevent KBD were suggested and a preventive program has been set up since 1998 in 20 new villages.

The prevalence of mycotoxins in Kashin-Beck disease

Mycotoxins are naturally occurring toxic chemical compounds produced by fungi infesting agricultural crops both during their growth and storage. Such secondary metabolites, when ingested, can produce toxic syndromes in humans. As it has been suggested that mycotoxins might be involved in the development of Kashin-Beck disease (KBD), we undertook a survey of barley grains of KBD-affected families and non-affected families in that country. We found, by thin layer chromatography, a hitherto unknown metabolite of Alternaria sp. This was especially common on the barley grains of KBD-affected families.

Reverse transcriptase-PCR analysis of bacterial rRNA for detection and characterization of bacterial species in arthritis synovial tissue

Onset of rheumatoid arthritis (RA) is widely believed to be preceded by exposure to some environmental trigger such as bacterial infectious agents. The influence of bacteria on RA disease onset or pathology has to date been controversial, due to inconsistencies between groups in the report of bacterial species isolated from RA disease tissue. Using a modified technique of reverse transcriptase-PCR amplification, we have detected bacterial rRNA in the synovial tissue of late-stage RA and non-RA arthritis controls. This may be suggestive of the presence of live bacteria. Sequencing of cloned complementary rDNA (crDNA) products revealed a number of bacterial sequences in joint tissue from each patient, and from these analyses a comprehensive profile of the organisms present was compiled. This revealed a number of different organisms in each patient, some of which are common to both RA and non-RA controls and are probably opportunistic colonizers of previously diseased tissue and others which are unique species. These latter organisms may be candidates for a specific role in disease pathology and require further investigation to exclude them as causative agents in the complex bacterial millieu. In addition, many of the detected bacterial species have not been identified previously from synovial tissue or fluid from arthritis patients. These may not be easily cultivable, since they were not revealed in previous studies using conventional in vitro bacterial culture methods. In situ hybridization analyses have revealed the joint-associated bacterial rRNA to be both intra- and extracellular. The role of viable bacteria or their nucleic acids as triggers in disease onset or pathology in either RA or non-RA arthritis controls is unclear and requires further investigation.