Recognition and management of bacterial arthritis

Real time monitoring of Staphylococcus aureus biofilm sensitivity towards antibiotics with isothermal microcalorimetry

Biofilm-associated infections with Staphylococcus aureus are difficult to treat even after administration of antibiotics that according to the standard susceptibility assays are effective. Currently, the assays used in the clinical laboratories to determine the sensitivity of S. aureus towards antibiotics are not representing the behaviour of biofilm-associated S. aureus, since these assays are performed on planktonic bacteria. In research settings, microcalorimetry has been used for antibiotic susceptibility studies. Therefore, in this study we investigated if we can use isothermal microcalorimetry to monitor the response of biofilm towards antibiotic treatment in real-time. We developed a reproducible method to generate biofilm in an isothermal microcalorimeter setup. Using this system, the sensitivity of 5 methicillin-sensitive S. aureus (MSSA) and 5 methicillin-resistant S. aureus (MRSA) strains from different genetic lineages were determined towards: flucloxacillin, cefuroxime, cefotaxime, gentamicin, rifampicin, vancomycin, levofloxacin, clindamycin, erythromycin, linezolid, fusidic acid, co-trimoxazole, and doxycycline. In contrast to conventional assays, our calorimetry-based biofilm susceptibility assay showed that S. aureus biofilms, regardless MSSA or MRSA, can survive the exposure to the maximum serum concentration of all tested antibiotics. The only treatment with a single antibiotic showing a significant reduction in biofilm survival was rifampicin, yet in 20% of the strains, emerging antibiotic resistance was observed. Furthermore, the combination of rifampicin with flucloxacillin, vancomycin or levofloxacin was able to prevent S. aureus biofilm from becoming resistant to rifampicin. Isothermal microcalorimetry allows real-time monitoring of the sensitivity of S. aureus biofilms towards antibiotics in a fast and reliable way.

Infectious arthritis and the temporomandibular joint. A review

OBJECTIVE

Microorganisms can cause acute infectious arthritis, chronic infectious arthritis, or reactive inflammatory arthritis. The aim of this study is to perform a narrative review of the pathophysiology, etiology, and diagnostic features of infectious arthritis and TMJ infectious arthritis.

METHODS

A search of the literature was performed using Medline, Scielo, Embase, and Google Scholar databases. The terms employed for the search were "Temporomandibular Joint Disorders" and "Infectious Arthritis"; or "Septic Arthritis"; or "Bacterial, Fungal, or Viral Arthritis." Over three hundred articles were screened for eligibility.

RESULTS

The selected articles were utilized to perform a narrative review of the general aspects of infectious arthritis and infectious arthritis affecting the TMJ.

CONCLUSION

Infectious arthritis is a rare, yet very morbid, form of arthritis. Understanding general aspects of joint infections and specific features of TMJ infectious arthritis is imperative for an adequate diagnosis.

Targeting intracellular Staphylococcus aureus to lower recurrence of orthopaedic infection

Staphylococcus aureus is often found in orthopaedic infections and may be protected from commonly prescribed antibiotics by forming biofilms or growing intracellularly within osteoblasts. To investigate the effect of non-antibiotic compounds in conjunction with antibiotics to clear intracellular and biofilm forming S. aureus causing osteomyelitis. SAOS-2 osteoblast-like cell lines were infected with S. aureus BB1279. Antibiotics (vancomycin, VAN; and dicloxacillin, DICLOX), bacterial efflux pump inhibitors (piperine, PIP; carbonyl cyanide m-chlorophenyl hydrazone, CCCP), and bone morphogenetic protein (BMP-2) were evaluated individually and in combination to kill intracellular bacteria. We present direct evidence that after gentamicin killed extracellular planktonic bacteria and antibiotics had been stopped, seeding from the infected osteoblasts grew as biofilms. VAN was ineffective in treating the intracellular bacteria even at 10× MIC; however in presence of PIP or CCCP the intracellular S. aureus was significantly reduced. Bacterial efflux pump inhibitors (PIP and CCCP) were effective in enhancing permeability of antibiotics within the osteoblasts and facilitated killing of intracellular S. aureus. Confocal laser scanning microscopy (CLSM) showed increased uptake of propidium iodide within osteoblasts in presence of PIP and CCCP. BMP-2 had no effect on growth of S. aureus either alone or in combination with antibiotics. Combined application of antibiotics and natural agents could help in the treatment of osteoblast infected intracellular bacteria and biofilms associated with osteomyelitis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1086-1092, 2018.

Acute hematogenous septic arthritis of the knee in adults

PURPOSE OF STUDY

To evaluate the factors associated with acute hematogenous septic arthritis of the knee in adults and to assess the outcome after open knee arthrotomy.

METHODS

We performed a prospective evaluation of 26 adult patients with acute nongonococcal septic arthritis of the knee presenting within 7 days. All patients underwent open knee arthrotomy, and final evaluation by means of Knee society score of the affected knee was compared with the contra lateral normal knee.

RESULTS

The average duration of symptoms at the time of presentation was 3.9 days. Staphylococcus aureus was the commonest bacteria isolated in 17 (65.4 %) patients. The average duration of follow-up in our study was 18.5 months. In our study, Knee society score decreases as the age of the patient advances (P < 0.05) and also it was found to be low (P < 0.05) in the affected knee as compared to contra lateral normal knee.

CONCLUSION

Our study shows that age of the patient at presentation is critical as it shows significant reduction in knee score. This explains that the septic arthritis may contribute to the progression of age-related degeneration of the knee joint. There appears to be no definite contributing factors or conditions associated with acute hematogenous septic arthritis of the knee in adults, although further study may be warranted regarding this matter.

Treatment of septic knee arthritis: comparison of arthroscopic debridement alone or combined with continuous closed irrigation-suction system

BACKGROUND

Arthroscopic debridement has been widely adapted as initial treatment for septic knee arthritis. Although isolated cases of arthroscopic debridement combined with irrigation-suction systems have been reported, a comparison of two techniques has not been performed, to our knowledge. The purpose of this study was to compare the two methods of treatment.

METHODS

From January 1996 to December 2008, 39 patients with 39 septic knee arthritis treated in our institution were retrospectively analyzed. Nineteen knees were initially treated with arthroscopic debridement alone (group I), and 20 knees were initially treated with arthroscopic debridement combined with continuous closed irrigation-suction system (group II). The clinical presentation, laboratory and microbiologic findings, hospital course, and clinical outcomes were compared between the two groups.

RESULTS

The mean delay between the onset of the symptoms and treatment had a significant effect on the clinical outcomes. When the comparison included all the patients in the series, no significant difference between the two groups was found with regard to the number of operation procedures required or the length of the hospital stay. However, when the comparison was separated from the initial stage of infection, it was found that in stage II infection, patients had fewer reoperations and in stages II and III infection, a shorter hospital stay in group II than in group I (p < 0.05). There was no significant difference in the functional results between the two groups.

CONCLUSIONS

The early diagnosis and aggressive initiation of treatment carried the success of therapy in septic knee arthritis. Arthroscopic debridement combined with continuous closed irrigation-suction system is an effective treatment for patients with septic knee arthritis; these patients had fewer operations and a shorter hospital stay than did patients who had received arthroscopic debridement alone.

Results of treatment of septic knee arthritis: a retrospective series of 40 cases

We studied a consecutive series of 40 patients presenting a septic knee arthritis, with a mean age of 49 +/- 20 (range 19-81) years. The aetiologies were: 18 postoperative arthritis, 12 haematogenous infections, 7 arthritis following aspiration or infiltration, and 3 articular wounds. The most common organisms were Staphylococcus aureus and epidermidis (23 cases). Surgical procedures consisted in 20 arthroscopic debridements, 6 open debridements, 14 synovectomies. According to Gächter's classification, there were 8 stage I, 18 stage II, 11 stage III and 3 stage IV cases. Fifteen patients had to be reoperated after the index procedure at our institution: one open debridement, six open synovectomies, one open arthrolysis, one arthrodesis and six total knee arthroplasties (TKA). Final examination was performed after 22 +/- 26 (range 12-96) months. All cases were considered free of infection. Good functional result was present by 19/33 cases (excluding arthrodesis and TKA). The delay between the onset of symptoms and surgery was the major prognostic factor of success (P=0.023). This delay was correlated with Gächter's staging of the intra-articular lesions. The diagnosis of septic knee arthritis must be suspected at the early stage of the disease, and diagnostic joint aspiration must be immediately performed when the diagnosis is suspected. We suggest that the treatment should be more aggressive than generally advocated. Needle aspiration should be only performed at the very early stages. Arthroscopic debridement should be the routine treatment. Synovectomy should be considered even as a primary procedure when significant synovial hypertrophy is present (Gächter stage III and IV) or when a more conservative treatment did not lead to a fast improvement.

Detection of bacterial DNA in synovial fluid from horses with infectious synovitis

Standard culturing techniques are often unrewarding in confirming diagnosis of synovial infection in the equine patient. Several human studies report the use of sensitive polymerase chain reaction (PCR) techniques for the detection of bacterial involvement in acute synovitis. However, successful extraction of bacterial DNA directly from clinical samples from horses without prior culture has not been reported yet. The goal of this study was to develop a sensitive and reliable method for molecular detection and identification of bacterial species in synovial fluid from horses with infectious synovitis. Synovial fluid samples from 6 horses with culture confirmed synovial infection were used for broad range 16S rRNA gene PCR. Synovial aspirates of 2 healthy horses were used as negative controls. Following extraction and purification of synovial fluid DNA, all samples were processed by touchdown PCR. Amplicons were detected by reverse line blot hybridisation and visualised with chemiluminescence. Pathogen-specific detection of 16S rRNA gene sequences was successful in all 6 synovial fluid samples. No bacterial DNA was detected in the aspirates from the negative control horses using touchdown PCR followed by 25 additional cycles of amplification. The identity of the pathogens was confirmed by DNA sequencing of the amplicons. It can be concluded that broad range 16S rRNA gene PCR followed by reverse line blot hybridisation is a promising technique for detection of bacterial DNA in synovial fluid samples. Further research should aim at the detection of bacterial DNA in synovial fluid samples suspected of infection but having negative culture results. When the 16S PCR proves to be reliable and more sensitive than standard culturing techniques, it may become a powerful tool in the diagnosis of synovial infection.

Prospective comparative study of patients with culture proven and high suspicion of adult onset septic arthritis

OBJECTIVE

To investigate whether patients with acute septic arthritis (SA) diagnosed by positive synovial fluid (SF) culture (Newman grade A) have different clinical and serological features from those with sterile SF in whom there is nonetheless a high suspicion of SA (Newman grades B and C).

PATIENTS AND METHODS

A prospective 12 month multicentre hospital based study of adult patients with SA recruited 47 patients with culture positive SA and 35 patients with clinically suspected SA but sterile SF.

RESULTS

Patient demography, clinical and laboratory features at presentation were similar irrespective of the underlying diagnosis, SF culture, and the presence of prosthetic joints. Medical and surgical treatment and outcome were comparable in the two patient groups. Patients with both suspected and proven SA were more likely to be from the more socially deprived areas of our community (p<0.0001).

CONCLUSION

Patients in whom there is a high clinical suspicion of SA are comparable to those patients with SA with a positive SF culture and have similar morbidity and mortality on follow up. Therefore, if clinical suspicion of SA is high then it is correct to treat as SA in the absence of bacterial proof.

Inhibiting the inflammatory response in joint sepsis

PURPOSE: We created a rabbit model of infectious arthritis to test the effects of WRC-0470 (2-cyclohexylmethylidenehydarazinoadenosine), an adenosine analogue, and rolipram, a type IV phosphodiesterase inhibitor, on intra-articular white blood cell recruitment. Type of Study: Randomized trial involving mature rabbits. METHODS: Intra-articular injections ranging from 0 to 2,000 ng of Escherichia coli lipopolysaccharide (LPS) were tested as the infectious stimulus. The optimal LPS amount was determined based on synovial fluid analysis for white blood cell counts. A separate cohort of rabbits then received various intravenous concentrations of either rolipram, WRC-0470, or a combination of the 2 medications. Synovial fluid aspirations after a 6-hour incubation were analyzed for white blood cell counts. RESULTS: Intra-articular injections of 200 ng of LPS reproducibly generated an inflammatory response of 4,000 cells/mL of synovial fluid, establishing the use of this dose of LPS for our septic arthritis model. Following infusions of 10 µg/kg/min, the average white blood cell count dropped to 800 cells/mL for WRC-0470 (P <.01) and 1,225 cells/mL for rolipram (P <.05). A synergistic effect was seen with the combination of both medications at just 1.0 µg/kg/min, with a mean white blood cell count of 1,090 cells/mL (P <.01). CONCLUSIONS: Septic arthritis is a common clinical entity that frequently results in major long-term morbidity. Although bacteria can directly damage the articular surface, the cytokine-mediated immune response to the infection can exacerbate the insult by promoting the release of proteolytic enzymes by white blood cells. Currently, no established intervention exists that will decrease the inflammatory response to infectious challenges. Our study shows that WRC-0470 and rolipram effectively reduce the intra-articular recruitment of white blood cells in a septic arthritis model. Future investigations of these drugs will determine their ultimate degree of efficacy at limiting the joint destruction associated with septic arthritis.

Mechanisms of internalization of Staphylococcus aureus by cultured human osteoblasts

Staphylococcus aureus is an important bone pathogen, and evidence shows that this organism is internalized by chick osteoblasts. Here we report that S. aureus is internalized by human osteoblasts. Internalization was inhibited by monodansylcadaverine and cytochalasin D and to a lesser extent by ouabain, monensin, colchicine, and nocodazole. We propose that internalization occurs via a receptor-mediated pathway, requiring the participation of cytoskeletal elements, principally actin.

Bacterial arthritis in the elderly: an overview

The key to successful treatment of acute bacterial arthritis is early diagnosis and initiation of empirical antibacterial therapy. Treatment includes antimicrobial therapy, debridement of the infected joint and treatment of pain. Empirical antibacterial treatment should be re-evaluated as soon as the causative pathogen is identified from joint fluid and other cultures. Mobilisation with partial weight bearing is encouraged early during treatment. The outcome of properly treated bacterial arthritis in the elderly is generally favourable and at least 50% of patients may recover without developing secondary osteoarthritis.