Antibiotic treatment insufficient for established septic arthritis. Staphylococcus aureus experiments in rabbits

Longitudinal study of the interplay between the skin barrier and facial microbiome over 1 year

Skin is a diverse ecosystem that provides a habitat for microorganisms. The skin condition and the skin microbiome interact each other under diverse environmental conditions. This study was conducted on 10 study participants for a one-year, from September 2020 to August 2021, to investigate the variability of skin microbiome and skin biophysical parameters [TEWL, hydration, and elasticity (R5)] according to season, and to understand the interplay between skin microbiome and skin characteristics. We identified that Cutibacterium, Corynebacterium, Staphyloccocus, unclassified genus within Neisseriaceae, and Streptococcus were major skin microbial taxa at the genus level, and fluctuated with the seasons. Cutibacterium was more abundant in winter, while Corynebacterium, Staphylococcus, and Streptococcus were more abundant in summer. Notably, Cutibacterium and skin barrier parameter, TEWL, exhibited a co-decreasing pattern from winter to summer and showed a significant association between Cutibacterium and TEWL. Furthermore, functional profiling using KEGG provided clues on the impact of Cutibacterium on the host skin barrier. This study enhances our understanding of the skin microbiome and its interplay with skin characteristics and highlights the importance of seasonal dynamics in shaping skin microbial composition.

Failure rates in surgical treatment in adults with bacterial arthritis of a native joint: a systematic review of 8,586 native joints

INTRODUCTION

Most adult cases of bacterial-septic-arthritis of a native joint are effectively managed with a single surgical debridement, but some cases may require more than one debridement to control the infection. Consequently, this study assessed the failure rate of a single surgical debridement in adults with bacterial arthritis of a native joint. Additionally, risk factors for failure were assessed.

MATERIALS AND METHODS

The review protocol was registered on PROSPERO (CRD42021243460) before data collection and conducted in line with the 'Preferred Reporting Items for Systematic Reviews and Meta-Analyses' (PRISMA) guidelines. Multiple libraries were systematically searched to identify articles including patients reporting on the incidence of failure (i.e. persistence of infection requiring reoperation) of the treatment of bacterial arthritis. The quality of individual evidence were assessed using the Quality in Prognosis Studies (QUIPS) tool. Failure rates were extracted from included studies and pooled. Risk factors for failure were extracted and grouped. Moreover, we evaluated which risk factors were significantly associated with failure.

RESULTS

Thirty studies (8,586 native joints) were included in the final analysis. The overall pooled failure rate was 26% (95% CI 20 to 32%). The failure rate of arthroscopy and arthrotomy was 26% (95% CI 19 to 34%) and 24% (95% CI 17 to 33%), respectively. Seventy-nine potential risk factors were extracted and grouped. Moderate evidence was found for one risk factor (synovial white blood cell count), and limited evidence was found for five risk factors (i.e. sepsis, large joint infection, the volume of irrigation, blood urea nitrogen-test, and blood urea nitrogen/creatinine ratio).

CONCLUSION

A single surgical debridement fails to control bacterial arthritis of a native joint in approximately a quarter of all adult cases. Limited to moderate evidence exists that risk factors associated with failure are: synovial white blood cell count, sepsis, large joint infection, and the volume of irrigation. These factors should urge physicians to be especially receptive to signs of an adverse clinical course.

Mini Review Therapeutic Strategies Targeting for Biofilm and Bone Infections

Bone infection results in a complex inflammatory response and bone destruction. A broad spectrum of bacterial species has been involved for jaw osteomyelitis, hematogenous osteomyelitis, vertebral osteomyelitis or diabetes mellitus, such as Staphylococcus aureus (S. aureus), coagulase-negative Staphylococcus species, and aerobic gram-negative bacilli. S. aureus is the major pathogenic bacterium for osteomyelitis, which results in a complex inflammatory response and bone destruction. Although various antibiotics have been applied for bone infection, the emergence of drug resistance and biofilm formation significantly decrease the effectiveness of those agents. In combination with gram-positive aerobes, gram-negative aerobes and anaerobes functionally equivalent pathogroups interact synergistically, developing as pathogenic biofilms and causing recurrent infections. The adhesion of biofilms to bone promotes bone destruction and protects bacteria from antimicrobial agent stress and host immune system infiltration. Moreover, bone is characterized by low permeability and reduced blood flow, further hindering the therapeutic effect for bone infections. To minimize systemic toxicity and enhance antibacterial effectiveness, therapeutic strategies targeting on biofilm and bone infection can serve as a promising modality. Herein, we focus on biofilm and bone infection eradication with targeting therapeutic strategies. We summarize recent targeting moieties on biofilm and bone infection with peptide-, nucleic acid-, bacteriophage-, CaP- and turnover homeostasis-based strategies. The antibacterial and antibiofilm mechanisms of those therapeutic strategies include increasing antibacterial agents’ accumulation by bone specific affinity, specific recognition of phage-bacteria, inhibition biofilm formation in transcription level. As chronic inflammation induced by infection can trigger osteoclast activation and inhibit osteoblast functioning, we additionally expand the potential applications of turnover homeostasis-based therapeutic strategies on biofilm or infection related immunity homeostasis for host-bacteria. Based on this review, we expect to provide useful insights of targeting therapeutic efficacy for biofilm and bone infection eradication.

Medical versus surgical treatment in native hip and knee septic arthritis

OBJECTIVE

Antibiotic treatment and arthroscopic or open drainage is the gold standard for septic arthritis. Full recovery takes time after surgery and hospital stay is longer than for arthrocentesis at the bedside. We aimed to evaluate the effectiveness of arthrocentesis (medical approach) versus a surgical approach.

METHOD

We retrospectively included 97 cases of native joint arthritis (hip and knee) between 2010 and 2017. The primary outcome was treatment failure of medical and surgical approaches (defined as surgical intervention within 7 days following diagnosis). Risk factors of failure were identified by univariable and multivariable logistic regression.

RESULTS

We included 72 cases of knee arthritis, of which 43 and 29 were treated medically and surgically, respectively; 25 cases of hip arthritis, of which 8 and 17 were treated medically and surgically, respectively. Failure was observed in 39.2% of cases in the medical group and in 30.4% in the surgical group (P=0.2) (37.5% vs. 52.9% and 39.5% vs. 17.2% for hip and knee, respectively). The univariate analysis identified age and male sex as risk factors for failure (P=0.048 and P=0.02, respectively), but only age was independently associated with failure (P=0.04). Hospital length of stay was 12 days shorter in the medical group (21 vs. 33 days, P=0.02), sequelae were less frequent and less important in the medical group (31.7% vs. 60%).

CONCLUSION

The medical treatment seems to be as effective as the surgical treatment for native joint septic arthritis with a shorter hospital stay and better functional outcome. Further prospective studies are warranted.

Evaluation of the effect of intraperitoneal etanercept administration on oxidative stress and inflammation indicators in the kidney and blood of experimental sepsis-induced rats

INTRODUCTION:

Sepsis is an important cause of mortality and morbidity, and inflammatory response and oxidative stress play major roles underlying its pathophysiology. Here, we evaluated the effect of intraperitoneal etanercept administration on oxidative stress and inflammation indicators in the kidney and blood of experimental sepsis-induced rats.

METHODS:

Twenty-eight adult Sprague Dawley rats were classified into Control (Group 1), Sepsis (Group 2), Sepsis+Cefazolin (Group 3), and Sepsis+Cefazolin+Etanercept (Group 4) groups. Kidney tissue and serum samples were obtained for biochemical and histopathological investigations and examined for the C reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), triggering receptor expressed on myeloid cells (TREM), and malondialdehyde (MDA) levels.

RESULTS:

The levels of TNF-α, TREM, and MDA in serum and kidney samples were significantly higher in rats from sepsis group than in rats from control group (p < 0.05). Group 3 showed a significant reduction in serum levels of TNF-α, CRP, and TREM as compared with Group 2 (p < 0.05). Serum TNF-α, CRP, TREM, and MDA levels and kidney TNF-α and TREM levels were significantly lower in Group 4 than in Group 2 (p < 0.05). Serum TNF-α and TREM levels in Group 4 were significantly lower than those in Group 3, and histopathological scores were significantly lower in Group 3 and Group 4 than in Group 2 (p < 0.05). Histopathological scores of Group 4 were significantly lower than those of Group 3 (p < 0.05).

CONCLUSIONS:

Etanercept, a TNF-α inhibitor, may ameliorate sepsis-induced oxidative stress, inflammation, and histopathological damage.

Neutralization of MMP-2 and TNFR1 Regulates the Severity of S. aureus-Induced Septic Arthritis by Differential Alteration of Local and Systemic Proinflammatory Cytokines in Mice

Despite advancement in the field of antibiotics septic arthritis remains a serious concern till date. Staphylococcus aureus is the most common bacterium that causes septic arthritis. Severity of this disease is directly correlated with chronic inflammation induced by proinflammatory cytokines like TNF-α, interleukin (IL)-1β, IL-6, and induction of matrix metalloproteinases (MMPs) including MMP-2. The objective of our study was to evaluate the role of MMP-2 and tumor necrosis factor receptor 1 (TNFR1) in the pathogenesis of S. aureus infection-induced septic arthritis. Mice were infected with live S. aureus (5 × 10⁶ cells/ml) followed by administration of MMP-2 inhibitor and TNFR1 antibody. Arthritis index showed highest reduction in severity of arthritis in mice treated with both MMP-2 inhibitor and TNFR1 antibody after infection. Combined neutralization of MMP-2 and TNFR1 led to marked diminution in bacterial count in the combined group. Lowest levels of pro inflammatory cytokines like TNF-α, IL-1β, IL-6, and IFN-γ were observed in both serum and synovial tissues indicating maximum protection in S. aureus arthritis during combination treatment. Increment in the level of IL-10 in the combination group could be positively correlated with the recovery of arthritis. Similarly, expressions of COX-2 and iNOS, markers of acute inflammation were also significantly reduced in the combination group due to resolution of inflammation. Levels of O2^.- and NO also showed a significant fall in case of the group treated with MMP-2 inhibitor and TNFR1 antibody both. Neutralization of both MMP-2 and TNFR1 caused rapid decline in recruitment of neutrophil and macrophages in the synovial tissues as evident from reduced MPO and MCP-1 levels, respectively, compared to other groups. Overall, it can be suggested that administration of MMP-2 inhibitor and TNFR1 antibody in combination is protective against the severity of inflammation and cartilage destruction associated with S. aureus infection-induced septic arthritis by altering the levels of cytokines.

Patient Factors Associated With Methicillin-Resistant Staphylococcus aureus Septic Arthritis in Children

Staphylococcus aureus is the most common causative organism in pediatric septic arthritis, with methicillin-resistant Staphylococcus aureus (MRSA) being responsible for a significant portion of these infections. Early identification and initiation of proper treatment may improve outcomes by minimizing potential morbidity. The purpose of this study was to identify variables obtained on initial patient presentation associated with MRSA septic arthritis. Sixteen factors were retrospectively evaluated in 109 consecutive pediatric patients diagnosed with culture-confirmed septic arthritis. Graphical and logistical regression analyses were employed to determine factors independently predictive of MRSA septic arthritis. Twenty-seven (25%) patients had MRSA and 82 (75%) had non-MRSA septic arthritis. C-reactive protein of 13.7 mg/L or greater, duration of symptoms of 4 days or more, heart rate of 126 beats per minute or greater, and absolute neutrophil count of 8.72×10³ cells/µL or greater were associated with MRSA septic arthritis. Ultimately, 98% of patients with 1 or no risk factors had non-MRSA and 96% of patients with MRSA septic arthritis had 2 or more positive risk factors. Elevated C-reactive protein, duration of symptoms, heart rate, and absolute neutrophil count are predictive of MRSA infection in the setting of pediatric septic arthritis and can be obtained on initial evaluation. In patients for whom there is concern for MRSA infection, this may guide more expedient treatment, such as early initiation of contact precautions and appropriate antibiotic therapy before culture results become available. [Orthopedics. 2018; 41(2):e277-e282.].

Spontaneous tibiotalar arthrodesis as a complication of acute tibial osteomyelitis due to Panton-Valentine leukocidin-producing Staphylococcus aureus: a case report

Introduction

Strains of Panton-Valentine leukocidin-producing Staphylococcus aureus producing a new pattern of disease have emerged worldwide. Infection with these bacteria typically presents as a life-threatening infection of soft tissues and bones, and may cause potentially devastating consequences.

Case presentation

We report a case of osteoarticular infection caused by Panton-Valentine leukocidin-producing Staphylococcus aureus. A 12-year-old Caucasian girl presented with acute osteomyelitis of the tibia associated with toxic shock syndrome, which was complicated by an unexpected spontaneous ankle arthrodesis.

Conclusions

Osteoarticular infections due to Panton-Valentine leukocidin-producing Staphylococcus aureus appear to be severe, and are characterized by their tendency to evolve towards serious complications. This case highlights the need for early and aggressive surgical procedures in conjunction with appropriate antimicrobial therapy and regular long-term follow-up.

Arthroscopic washout of the ankle for septic arthritis in a three-month-old boy

There is no report of athroscopic treatment for septic arthritis of the ankle in infants. We report a case of successful management of septic arthritis of the ankle in a three-month-old boy by arthroscopic washout. Arthroscopic washout may be a useful treatment for septic arthritis in young infants when performed early after onset.

The combination of a tumor necrosis factor inhibitor and antibiotic alleviates staphylococcal arthritis and sepsis in mice

BACKGROUND

Despite advances in medical practices, in recent decades permanent reductions in joint function have not been achieved, and the high mortality rate of patients with staphylococcal septic arthritis has not substantially improved.

METHODS

We evaluated the effects of a combined tumor necrosis factor (TNF) inhibitor and antibiotic therapy on the course of Staphylococcus aureus arthritis and sepsis in mice.

RESULTS

Treatment with the combination of a TNF inhibitor and an antibiotic resulted in a quicker relief of clinical arthritis in mice with septic arthritis, compared with an antibiotic monotherapy. Both histopathologically verified synovitis and the extent of joint destruction were reduced by this combined treatment. Importantly, anti-TNF treatment significantly improved the survival rate of mice with S. aureus sepsis and staphylococcal enterotoxin shock syndrome; this effect might be the result of a partial restoration of the hemostatic balance between coagulation and fibrinolysis. Finally, we demonstrated that anti-TNF treatment downregulates high-mobility group protein B1 in staphylococcal enterotoxin shock syndrome.

CONCLUSIONS

Thus, simultaneous systemic TNF inhibition and antibiotic therapy has beneficial effects on the outcome of S. aureus arthritis and sepsis in a mouse model, suggesting that the combination of a TNF inhibitor and antibiotics represents a novel therapeutic strategy for the treatment of staphylococcal infections.

Effect of intraarticular propolis in an experimental septic arthritis model

To evaluate the efficacy and safety of intraarticular propolis compared with systemic antibiotic treatment in an experimental septic arthritis model. Thirty-two rabbits were infected intraarticularly by Staphylococcus aureus. The rabbits were randomly divided into four groups, including a control group and three experimental groups. Drainage was the only procedure performed in group I (control group). The animals were treated with daily intramuscular cefazolin sodium (75 mg/kg) for 7 days in group II. In group III, intraarticular ethanolic extract of propolis (0.5 mg/ml) was injected to the infected knees under sterile conditions on days 7, 14, and 21 after drainage. In group IV, the rabbits received both intramuscular cefazolin sodium as in group II and intraarticular ethanolic extract of propolis as in group III. After 8 weeks, the animals were killed and joint histopathological and scanning electron microscopic parameters were assessed. The best clinical score was obtained in group IV. There were statistically significant differences among all the groups (P<0.05). The highest total score of the histological examination was found in group I and the best total score was obtained in group IV. There were statistically significant differences among the groups when we evaluated the scores of the parameters as loss of chondrocytes, loss of matrix, and pannus in-growth (P<0.05). But there was no significant difference among the groups for the scores of cloning of the chondrocytes (P>0.05). The highest scanning electron microscopy score was found in group I and the best score was obtained in group IV. Our results confirm the safety and efficacy of intraarticular propolis and synergistic effect of propolis when used with cefazolin in an experimental septic arthritis model.

Severe musculoskeletal infection variant in Lemierre's syndrome

Lemierre's syndrome is a severe complication of Fusobacterium necrophorum oropharyngeal infection associated with metastatic foci of infection, internal jugular vein thrombosis, and septicemia. Musculoskeletal manifestations include isolated or multifocal septic arthritis, soft tissue abscesses, pyomyositis, and osteomyelitis. This article describes a case of a variant of Lemierre's syndrome in a 17-year-old girl, demonstrating a relentless case of limb infection refractory to multiple surgical debridements and broad-spectrum and targeted antibiotics. The patient had F. necrophorum within a peritonsillar abscess and multiple foci within her right lower extremity. Overall, she required 12 surgical procedures and 14 weeks of antibiotic therapy to resolve the infection. Further unique findings in this case include the presence of a recent lateral meniscus tear with associated hemarthrosis treated with a short course of oral steroids prior to the diagnosis of septic arthritis. Knee arthroscopy with lysis of adhesions and manipulation at 6 months postinfection demonstrated significant chondral damage. Outcome at >2-year follow-up revealed pain-free activities of daily living and the ability to return to competitive, club-level collegiate softball. Clinically relevant findings illustrated in this case include potential development of antibiotic resistance within Fusobacterium genus with little to no response to several surgical debridements and broad-spectrum and targeted antibiotics, and development of multifocal, ipsilateral septic arthritis and soft tissue abscesses and pyomyositis in the context of steroid use and recent intra-articular knee injury.

Prospective evaluation of a shortened regimen of treatment for acute osteomyelitis and septic arthritis in children

BACKGROUND

We present the findings of a prospective, bi-center study to establish the appropriate duration of antibiotic therapy for acute, uncomplicated bone and joint infections in children. Historically, patients have been treated with prolonged courses of intravenous and oral therapy. Our hypothesis was that children could be safely treated with 3 days of high-dose intravenous therapy followed by 3 weeks of oral therapy.

METHODS

We prospectively collected data from children presenting to Birmingham Children's Hospital and The Royal Children's Hospital, Melbourne who fitted our diagnostic criteria for septic arthritis and osteomyelitis over a 52-month period. Inclusion criteria for entry into the database were children <or=16 years of age who had no underlying disease or medical therapy predisposing to infection, and who had symptoms for less than 14 days before presentation. They were all started on intravenous antibiotics and a predetermined treatment algorithm was followed. All patients with septic arthritis also underwent joint washout. The patients were converted to oral antibiotics once they improved clinically and hematologically. Regular outpatient follow-up continued for 1 year with blood tests and x-rays.

RESULTS

Our database included 70 consecutive, eligible children aged 2 weeks to 14 years. Staphylococci were the only organisms isolated in cases of osteomyelitis, whereas Streptococcal infection was more prevalent in patients with septic arthritis. Using our treatment protocol, we found that 59% of children could be converted to oral therapy after 3 days of intravenous therapy and 86% after 5 days. The median duration of inpatient stay was 5 days. We established that 3 weeks of oral therapy was appropriate for those patients who received 5 days or less intravenous treatment. We have identified temperature and C-reactive protein as the best quantitative means of monitoring response to therapy. All patients were clinically, hematologically, and radiologically normal before discharge 1 year post-presentation.

CONCLUSIONS

We have found that a shortened course of intravenous and oral antibiotic therapy is effective in the management of acute uncomplicated bone and joint sepsis in children.

Protective effects of intermittent hydrostatic pressure on osteoarthritic chondrocytes activated by bacterial endotoxin in vitro

The role of continuous passive motion (CPM) in the management of septic arthritis and inflammatory arthritis remains of interest. CPM produces cyclic variations in intraarticular pressure that facilitates transport of fluid, nutrients, and solutes within and/or across the joint and stimulates chondrocyte metabolism. However, the precise mechanisms mediating the responses of chondrocytes to joint motion remain unclear. This study tested the hypothesis that dynamic mechanical loading counteracts effects of bacterial lipopolysaccharide (LPS), an inflammatory mediator, on chondrocyte metabolism. Intermittent hydrostatic pressure (IHP) (10 MPa for 4 h) was applied to human chondrocytes pretreated with LPS (1 microg/ml for 18 h). LPS activation of chondrocytes decreased mRNA signal levels of type II collagen by 67% and aggrecan by 56% and increased nitric oxide by 3.1-fold, monocyte chemotactic protein-1 mRNA signal levels by 6.5-fold, and matrix metalloproteinase-2 mRNA signal levels by 1.3-fold. Application of IHP to LPS-activated chondrocytes decreased nitric oxide synthase mRNA signal levels and nitric oxide levels in the culture medium. Exposure of LPS-activated chondrocytes to IHP upregulated type II collagen and aggrecan mRNA signal levels by 1.7-fold, relative to chondrocytes activated by LPS and maintained without loading. In addition, application of IHP decreased the upregulation in signal levels of monocyte chemotactic factor-1 and matrix metalloproteinase-2 following LPS activation by 45% and 15%, respectively. These data show that mechanical loading counteract effects of inflammatory agents, such as bacterial LPS, and suggest that postinfection sequelae are influenced by the presence or absence of joint loading.

Acute septic arthritis

Acute septic arthritis may develop as a result of hematogenous seeding, direct introduction, or extension from a contiguous focus of infection. The pathogenesis of acute septic arthritis is multifactorial and depends on the interaction of the host immune response and the adherence factors, toxins, and immunoavoidance strategies of the invading pathogen. Neisseria gonorrhoeae and Staphylococcus aureus are used in discussing the host-pathogen interaction in the pathogenesis of acute septic arthritis. While diagnosis rests on isolation of the bacterial species from synovial fluid samples, patient history, clinical presentation, laboratory findings, and imaging studies are also important. Acute nongonococcal septic arthritis is a medical emergency that can lead to significant morbidity and mortality. Therefore, prompt recognition, rapid and aggressive antimicrobial therapy, and surgical treatment are critical to ensuring a good prognosis. Even with prompt diagnosis and treatment, high mortality and morbidity rates still occur. In contrast, gonococcal arthritis is often successfully treated with antimicrobial therapy alone and demonstrates a very low rate of complications and an excellent prognosis for full return of normal joint function. In the case of prosthetic joint infections, the hardware must be eventually removed by a two-stage revision in order to cure the infection.

Signal transduction pathways and apoptosis in bacteria infected chondrocytes

The mechanism underlying chronic destructive arthropathy after pyogenic arthritis is not clear. This study evaluated the role of apoptosis in Staphylococcus aureus infected human articular chondrocytes and investigated the signal transduction pathways activated by bacterial infection. Chondrocytes cultured in monolayer were challenged with bacteria for 6 h and were analyzed after incubation for 2, 18, and 24 h. Chondrocytes showed morphologic and biochemical evidences of apoptosis after infection and the following incubation period. Although treatment with extensive washing and vancomycin could ameliorate the amount of apoptosis from 31% to 15% at 2 h, from 48% to 23% at 18 h, and from 58% to 33% at 24 h, the infected samples with treatment still had higher amount of apoptosis than the un-infected controls (ANOVA P < 0.001). Accompanying with the increasing amount of apoptosis, the caspase activity was upregulated in bacteria infected samples and remained high in samples with treatment (ANOVA P < 0.05). Signal transduction pathways activated by bacterial infection were assessed by co-transfection technique. After infection, the c-Jun N-terminal kinase, extracellular signal-regulated kinase, and cyclic AMP-dependent protein kinase activities were elevated by 7.6-, 7.3-, and 3.2-fold, respectively, compared to the uninfected controls. The data support the hypothesis that human chondrocytes will undergo apoptosis after infection by a single organism. Apoptosis and activated intracellular kinase activities may be related to the pathogenesis of post-infectious destructive arthropathy.

Outcome of Staphylococcus aureus-triggered sepsis and arthritis in IL-4-deficient mice depends on the genetic background of the host

Disruption of the IL-4 gene in two inbred mouse strains revealed a dual role of IL-4 in Staphylococcus aureus sepsis and arthritis depending on the host's genetic background. IL-4 was protective in 129SV mice, since 5 days after S. aureus inoculation IL-4(-/-) mice displayed 70% mortality as compared to survival of all 129SV wild-type counterparts. On the other hand, IL-4 was detrimental in C57BL/6 mice, since survival of IL-4(-/-) C57BL/6 mice was increased, as compared to wild-type controls, due to decreased staphylococcal growth. Altogether, our results show the dual role of IL-4 in S. aureus sepsis and arthritis, depending on the genetic background of the host.

Treatment of staphylococcal septic arthritis in rabbits by systemic antibiotics and intra-articular corticosteroids

OBJECTIVE

To assess the effect of intra-articular corticosteroids added to systemic antibiotics in experimental septic arthritis.

METHODS

Rabbits were injected intra-articularly by Staphylococcus epidermidis. Rabbits received no additional treatment and served as control (group 1), were treated with systemic antibiotics (group 2), or treated with systemic antibiotics and intra-articular corticosteroids (group 3). After 15 days animals were killed and joint histopathological-histochemical parameters were assessed.

RESULTS

All rabbits survived the experiment. The treated groups (2-3) had lower histological-histochemical scores in comparison with the untreated group (1). Group 3 had significantly lower scores in joint sections in comparison with group 2: (mean (SD) 6.5 (1.4) v 4.0 (1.0), p = 0.001 and 7.4 (2.6) v 4.2 (2.2), p = 0.01), because of lower damage expressed in clustering of chondrocytes, pannus formation, proteoglycan depletion, and synovitis.

CONCLUSION

Addition of local corticosteroids to systemic antibiotics in septic arthritis seems to be harmless, and improves joint histological-histochemical parameters in this experimental setting.

Staphylococcal septic arthritis: antibiotic and nonsteroidal anti-inflammatory drug treatment in a rabbit model

This study evaluated the effects of combining antibiotic therapy with the application of a nonsteroidal anti-inflammatory drug on the degradation of articular cartilage for an animal model of Staphylococcal septic arthritis. Rabbits were infected intra-articularly with Staphylococcus aureus. Antibiotic treatment started 18 hours after infection and continued for 7 days. Treatment with the nonsteroidal anti-inflammatory drug naproxen sodium started 24 hours before infection and continued for either 3 or 7 weeks. The cartilage matrix of uninfected and infected knees was quantified by analysis of glycosaminoglycan and collagen content. Three weeks after infection, the combined treatment of the nonsteroidal anti-inflammatory drug and antibiotics reduced the loss of glycosaminoglycan and collagen from the cartilage of the infected knee by 15 and 30%, respectively, compared with antibiotic treatment alone. Continuing treatment with naproxen sodium for 7 weeks reduced the loss of collagen by 50% when compared with antibiotic treatment alone. The longer period of treatment with naproxen sodium showed little further effect on the loss of glycosaminoglycan than that observed for the 3-week treatment. Treatment with this drug and antibiotics reduced swelling of the knee and levels of prostaglandin E2 in the synovial fluid. The data support the hypothesis that decreasing post-infectious inflammation by adding the drug to a standard antibiotic regimen reduces cartilage damage from Staphylococcal septic arthritis.

Arthroscopically assisted treatment of acute septic knees in infants using the Micro-Joint Arthroscope

Five infants with an acute hematogenous septic arthritis of the knee were treated with arthroscopically assisted drainage using the Micro-Joint Arthroscope (MJA; Linvatec, Largo, FL) combined with antibiotic therapy and early postoperative motion. The average patient age was 16 months (range, 4 to 24 months). No surgical or anesthetic complications occurred. All knees were clinically and radiologically normal at an average follow-up of 26 months.

Evaluation of treatment modalities for septic arthritis with histological grading and analysis of levels of uronic acid, neutral protease, and interleukin-1

We compared the effectiveness of antibiotics alone and in combination with arthroscopy, arthroscopy with debridement, arthrotomy, or needle aspiration for the treatment of septic arthritis. Each modality has its proponents, but, to our knowledge, no comparative studies have been conducted in animals. We used biochemical and histological analysis to compare these methods of treatment in an experimental model. The right hind knee of thirty goats was injected with 1 x 10(5) Staphylococcus aureus bacilli. The left hind knee was not inoculated and served as the normal control. Seventy-two hours after inoculation, a two-week course of treatment with intramuscular administration of cefuroxime sodium, either alone or in combination with another mode of treatment, was initiated in each of five groups. The cartilage was evaluated histologically with biochemical, enzymatic, and interleukin-1 analyses. Despite the early therapeutic intervention, on the average, there was a 25 per cent loss of uronic acid (t test, p < 0.001) and a 43 per cent increase in neutral protease activity (signed-rank test, p = 0.003) in the treatment groups. There were no significant intergroup differences with regard to the histochemical-histological rating or the levels of uronic acid, neutral protease, or interleukin-1.

Synovectomy for septic arthritis. Early versus late synovectomy studied in the rabbit knee

Thirty rabbits with established unilateral septic arthritis of the knee after inoculation with Staphylococcus aureus received cloxacillin 50 mg/kg x 2 i.m. and probenecid 250 mg x 1 p.o. from Day 3 to 21. In 26 knees, synovectomy was performed 3, 5, and 7 days after the inoculation, and four knees were not operated on. Further, synovectomy was performed in eight noninfected knees. The rabbits were killed 3 or 7 weeks after the operation, and the specimens were examined macroscopically and microscopically. All the cultures taken postoperatively and at killing were negative. Infected knees synovectomized on Day 3 differed, although marginally, 3 weeks postoperatively from the operated on, uninfected group; a minor loss of cartilage cellularity and glycosaminoglycans was observed, but there were no changes indicating arthrosis. At 7 weeks postoperatively, this difference was more pronounced. If synovectomy was performed at a later stage, increased destruction was observed: after 7 days of infection, all the knees presented cloning and vascular crossing of the tidemark, indicating arthrosis, which did not differ from those knees treated with only antibiotics. We conclude that synovectomy performed early in the course of infection may stop the destructive influence of enzymes and of the synovial membrane leading to irreversible changes in the cartilage.