Serological diagnosis of Staphylococcus aureus osteomyelitis

We have evaluated serological tests for the diagnosis of Staphylococcus aureus osteomyelitis. Antiteichoic acid antibodies were elevated in 17 of 23 patients with acute and 16 of 46 with chronic S. aureus osteomyelitis but in none of 33 patients infected with other gram-positive or gram-negative bacteria. Immunoglobulin G antibodies to S. aureus were elevated in 12 of 23 patients with acute and 22 of 47 with chronic S. aureus osteomyelitis, in 2 of 12 infected with other gram-positive bacteria, and in 4 of 21 with other gram-negative bacteria. Assays for S. aureus antibodies may be useful for identifying patients with S. aureus bacteremia complicated by metastatic sites of infection in bone and for identifying the etiological agents in patients with negative or mixed cultures or from whom cultures are not readily available. Prospective studies are needed to test these hypotheses.     

Bacterial adherence and glycocalyx formation in osteomyelitis experimentally induced with Staphylococcus aureus

A surgical procedure allowed the placement of a silicone rubber catheter in the marrow cavity of the tibia of a rabbit and also allowed the introduction of a sclerosing agent (sodium morrhuate) and cells of Staphylococcus aureus. Osteomyelitis developed in 60% of the animals so treated, and the infecting microorganism was recovered from the infected tibias of the animals that developed this disease. All blood cultures taken 24 h after the infection were negative for S. aureus. Radiological findings consisted of osteolytic changes, the occurrence of sequestration and periosteal reactions, and sclerosis in the infected bones. Sections of bone prepared for histological examination confirmed the diagnosis of osteomyelitis. Transmission and scanning electron microscopy of samples of bone marrow, bone chips, and the catheters taken from the infected tibiae revealed gram-positive cocci embedded in a very extensive matrix of ruthenium red-staining glycocalyx adhering to the bone and the implanted catheter. It is proposed that this extensive glycocalyx served a protective function for the bacteria and was important in bacterial adherence and thus played an important role in bacterial persistence and the development of osteomyelitis in these rabbits.     

Emergence of a clinical daptomycin-resistant Staphylococcus aureus isolate during treatment of methicillin-resistant Staphylococcus aureus bacteremia and osteomyelitis

The emergence of a clinically daptomycin-resistant Staphylococcus aureus isolate occurred during treatment of methicillin-resistant S. aureus bacteremia and probable vertebral osteomyelitis. The breakthrough isolate was indistinguishable from pretreatment daptomycin-susceptible isolates by pulsed-field gel electrophoresis. Daptomycin nonsusceptibility was confirmed by MIC and time-kill curve analyses.     

抗生素骨水泥链置入在慢性骨髓炎行病灶清除后的感染控制

目的探讨慢性骨髓炎在采用抗生素骨水泥链进行治疗后的感染控制。方法将我院收治的50例慢性骨髓炎患者随机分为研究组和对照组,病灶清除后,分别给予患者抗生素骨水泥链置入处理和闭合灌洗引流术,观察患者的平均住院时间、平均手术次数以及治愈率。结果研究组21例患者平均住院时间为(65±4.2)d;平均手术次数为(2.3±1.2)次;患者的治愈率为85.7%。对照组29例患者平均住院时间为(103±2.5)d;平均手术次数为(2.8±1.4)次;患者治愈率为55.2%。2组比较差异具有统计学意义(P0.05)。结论抗生素骨水泥链治疗慢性骨髓炎具有良好效果,减少患者的住院时间和手术次数,提高治愈率,病灶清除后的感染控制效果好。     

Enterotoxin production by Staphylococcus aureus strains isolated from cases of chronic osteomyelitis.

Of 264 Staphylococcus aureus strains selected at random from 3,978 strains isolated from chronic osteomyelitis patients, 79 were found to produce enterotoxin. A majority of the strains (65%) were nontypable by phages belonging to the international phage set for human strain typing. The significance of these strains and their circulation among the population is discussed, especially from the standpoint of their possible role in the development of osteomyelitis.     

骨搬移术治疗慢性骨髓炎致下肢长骨骨缺损中的并发症研究

目的 探讨使用骨搬移术治疗慢性骨髓炎所致下肢长骨骨缺损中的并发症发生情况。方法 回顾性分析武汉市第三医院于2015年3月至2017年4月期间接收的32例慢性骨髓炎致下肢长骨骨缺损应用骨搬移术治疗的患者手术操作及术后并发症发生情况,并对相关并发症行相关性研究,踝关节功能受限与搬移方向、软组织条件以及治疗时间行相关性分析,对线不良与外固定类型、骨缺损部位以及骨缺损长度行相关性分析。结果 32例慢性骨髓炎致下肢长骨骨缺损应用骨搬运技术治疗后,踝受限18例,对线不良12例,其中同时并发踝关节受限及对线不良9例,2例无明显并发症恢复良好。同时对踝受限行相关分析,发现踝受限与搬移方向、软组织条件以及治疗时间并无相关性;对线不良与外固定类型、骨缺损部位以及骨缺损长度无相关性。结论 应用骨搬移术治疗慢性骨髓炎所致下肢长骨骨缺损效果良好,尽管有相关并发症,但是只要经过合理的处理,对患者疾病的康复有重要意义,为患者带来更好的康复治疗。     

Antibody response to Staphylococcus aureus surface proteins in rabbits with persistent osteomyelitis after treatment with demineralized bone implants.

A rabbit model was used to study the effect of allogeneic demineralized bone powder (DBP) implants on the persistence of Staphylococcus aureus osteomyelitis. Thirty-one rabbits with chronic osteomyelitis of the tibia established by day 21, were started on systemic antibiotics followed by either no additional treatment or debridement plus either DBP (with or without supplemental antibiotics) or supplemental antibiotics only. On day 21, cultures showed a mean of 2 x 10(4) CFU/mg of debrided osseous material. By day 70, the treatment most effective in clearing infection was found in animals treated with supplemental antibiotics only (mean of 142 +/- 116 CFU/mg). In contrast, infection persisted at a 7- to 10-fold-higher level in animals receiving DBP with and without supplemental antibiotics; these results suggest that DBP contributed to persistence of infection. Longitudinal sera were tested again staphylococcal sonic extracts by immunoblot. Detection of numerous probe-positive bands indicated complex but remarkably similar antibody responses among infected animals. Antibodies attached directly to the cell surfaces of staphylococci as shown by immunogold and blocked the binding of organisms to HEp-2 and human fetal lung cells in a radioadherence assay. Antibodies could be absorbed out by intact organisms and were unreactive by immunoblot against antigens derived from cells pretreated with pronase, proteinase K, or lysostaphin. These results indicate that the major response was directed against staphylococcal cell surface proteins. Surprisingly, only one major band (molecular weight, approximately 12,000) was detected when a homologous in vivo antigen preparation was studied by immunoblot. Antibody reactive against this peptide did not appear to react with staphylococci grown in vitro.     

Emerging pathogenetic mechanisms of the implant-related osteomyelitis by Staphylococcus aureus

Implant-related osteomyelitis is a severe and deep infection of bone that arises and develops all around an implant. Staphylococcus aureus is the first cause of osteomyelitis, whether implant-related or not. Bone is an optimal substratum for S. aureus, since this bacterium expresses various adhesins by which can adhere to bone proteins and to the biomaterial surfaces coated with the proteins of the host extracellular matrix. S. aureus is able not only to colonize bone tissues, but also to invade and disrupt them by entering bone cells and inducing cell death and osteolysis. Here we illustrate the pathogenetic mechanisms that can explain how the osteomyelitis sets in and develops around an implant.     

A rat model of Staphylococcus aureus chronic osteomyelitis that provides a suitable system for studying the human infection

Chronic osteomyelitis was produced by inoculating Staphylococcus aureus into rat tibia. The infection was characterised grossly by bone deformation and histopathologically by inflammation and the presence of coccal organisms sequestered within the bone tissue. Further observations by scanning electronmicroscopy demonstrated bacteria in microcolonies surrounded by dehydrated amorphous material that was considered to be glycocalyx. Transmission electronmicroscopy, when aided by antibody stabilisation, revealed extensive glycocalyx production within the tibia. These findings indicate that the rat model of chronic S. aureus osteomyelitis mimics the human infection with respect to the sessile mode of growth of bacteria within the bone. Serum antibody levels were assayed by ELISA and immunoblotting procedures. After an initial increase, ELISA titres remained relatively stable, apparently indicating the establishment of chronic osteomyelitis, whereas in immunoblotting an increase in titre over the course of infection was observed. Whole-cell ELISA revealed less subtle differences in antibody titre than did immunoblotting with cell-wall antigen. We found that mid-range antigens, including an antigen implicated as protein A, featured prominently in the immune response in this model of infection.     

Osteoblasts express the inflammatory cytokine interleukin-6 in a murine model of Staphylococcus aureus osteomyelitis and infected human bone tissue

Staphylococcus aureus is the single most common cause of osteomyelitis in humans. Incidences of osteomyelitis caused by S. aureus have increased dramatically in recent years, in part due to the appearance of community-acquired antibiotic resistant strains. Therefore, understanding the pathogenesis of this organism has become imperative. Recently, we have described the surprising ability of bone-forming osteoblasts to secrete a number of important immune mediators when exposed to S. aureus in vitro. In the present study, we provide the first evidence for the in vivo production of such molecules by osteoblasts during bacterial infection of bone. These studies demonstrate the expression of the key inflammatory cytokine interleukin-6 by osteoblasts in organ cultures of neonatal mouse calvaria, and in vivo using a mouse model that closely resembles the pathology of trauma-induced staphylococcal osteomyelitis, as determined by confocal microscopic analysis. Importantly, we have established the clinical relevancy of these findings in infected human bone tissue from patients with S. aureus-associated osteomyelitis. As such, these studies demonstrate that bacterial challenge of osteoblasts during bone diseases, such as osteomyelitis, induces cells to produce inflammatory molecules that can direct appropriate host responses or contribute to progressive inflammatory damage.     

抗生素骨水泥结合膜诱导技术治疗胫骨骨髓炎的临床研究

目的观察研究使用抗生素骨水泥抗感染并形成诱导膜,采用膜诱导自体骨或结合异体骨材料移植技术治疗胫骨骨髓炎及其术后骨缺损的临床效果。方法自2010年9月~2015年9月手术治疗15例胫骨骨髓炎患者,一期病变切除,抗生素骨水泥植入,外固定支架固定,6~8周诱导膜形成后二期手术取出骨水泥,自体骨或结合异体骨材料移植,采用膜诱导技术修复骨缺损促进骨质愈合。结果随访12~52月,15例患者感染无复发,骨折均获愈合,功能恢复良好。结论采用抗生素骨水泥膜诱导自体骨或结合异体骨材料移植技术治疗胫骨骨髓炎及其术后骨缺损可以取得良好的治疗效果。     

Antibody response to teichoic acid and peptidoglycan in Staphylococcus aureus osteomyelitis.

An enzyme-linked immunosorbent assay was used to evaluate the immunoglobulin G (IgG) response to Staphylococcus aureus crude teichoic acid (TA) and peptidoglycan (PG) in both rabbits and patients with osteomyelitis. In rabbits with experimental S. aureus osteomyelitis, elevated levels of IgG to TA were present in 13/18 (72%) of the serum samples obtained at 4 and 10 weeks postinfection. In contrast, only 5/18 (28%) of these sera were found to be positive for antibodies to PG. Of a total of 39 patients with confirmed S. aureus osteomyelitis (11 acute, 28 chronic), IgG to TA was elevated in 17 (44%), whereas antibodies to PG were found to be increased in only 1 (3%). Cross-reacting antibodies to S. aureus TA were detected in only 1/18 (6%) of the patients with osteomyelitis caused by organisms other than S. aureus. These studies indicate that IgG to TA is more prevalent than IgG to PG in patients with staphylococcal osteomyelitis. Although these results are encouraging, a larger number of patients is required for an adequate evaluation of the TA enzyme-linked immunosorbent assay for the diagnosis and management of suspected S. aureus osteomyelitis.     

Ultrastructural studies of adherence of Staphylococcus aureus in experimental acute hematogenous osteomyelitis.

A model of acute hematogenous osteomyelitis initiated by injection of Staphylococcus aureus into 29-day-old chickens was used. Transmission electron microscopy showed that the bacteria adhered to exposed cartilage matrix in the metaphyseal region of long bones but not to adjacent vascular linings or to erythrocytes. It is proposed that the combination of exposure of growth plate cartilage during normal bone growth and the ability of S. aureus to adhere to this cartilage is the mechanism for initiation of infection which proceeds to an osteomyelitic abscess.     

Capsule-negative Staphylococcus aureus induces chronic experimental mastitis in mice

Staphylococcus aureus capsular polysaccharides (CP) have been shown to enhance staphylococcal virulence in numerous animal models of infection. Although serotype 5 CP (CP5) and CP8 predominate among S. aureus isolates from humans, most staphylococcal isolates from bovines with mastitis in Argentina are capsule negative. This study was designed to evaluate the effects of CP5 and CP8 expression on the pathogenesis of experimental murine mastitis. Lactating mice were challenged by the intramammary route with one of three isogenic S. aureus strains producing CP5, CP8, or no capsule. Significantly greater numbers of acapsular mutant cells were recovered from the infected glands 12 days after bacterial challenge compared with the encapsulated strains. Histopathological analyses revealed greater polymorphonuclear and mononuclear leukocyte infiltration and congestion in the mammary glands of mice infected with the encapsulated strains compared with the acapsular mutant, and the serotype 5 strain elicited more inflammation than the serotype 8 strain. In vitro experiments revealed that the acapsular S. aureus strain was internalized by MAC-T bovine epithelial cells in significantly greater numbers than the CP5- or CP8-producing strain. Taken together, the results suggest that S. aureus lacking a capsule was able to persist in the murine mammary gland, whereas encapsulated strains elicited more inflammation and were eliminated faster. Loss of CP5 or CP8 expression may enhance the persistence of staphylococci in the mammary glands of chronically infected hosts.