Aim. Toxin-antitoxin (TA) systems are small genetics elements found in the majority of bacteria which encode a toxin causing bacterial growth arrest and an antitoxin counteracting the toxic effect. In Salmonella and E. coli, TA systems were shown to be involved in the formation of persisters. Persisters are a bacterial subpopulation with low growth rate and high tolerance to antibiotics. They could be responsible for antibiotic treatment failure in chronic infections and relapses, notably in bone and joint infections (BJI) caused by Staphylococcus aureus. Currently, two type II TA system families were described in S. aureus, mazEF and axe/txe, but their physiological roles are not well described. In this work, we studied the importance of mazEF in the intracellular survival of S. aureus inside osteoblasts, one of the mechanisms considered in the chronicity of S. aureus BJI. Methods. Using an ex vivo model of intracellular infection of human osteoblast-like cells (MG-63), two strains of S. aureus HG003 wild type and its isogenic mutant HG003 ΔmazEF were compared in terms of : i) internalization and intracellular survival by lysostaphin protective assay and ii) cytotoxicity by quantifying LDH in the culture supernatant, 24h and 48h after infection. Results. The comparison of the two strains revealed that HG003 ΔmazEF had a lower capacity to be internalized by osteoblasts compared to the wild type (p=0.02). However, intracellular survival was greater for HG003 ΔmazEF compared to the wild type 24h and 48h post-infection (p=0.02 and 0.001 respectively). Concerning the bacteria-induced cell death, HG003 ΔmazEF appeared to be less cytotoxic than the wild type strain at 24h post infection (p=0.007) whereas no more differences could be observed after 48h. This delayed cytotoxicity with HG003 ΔmazEF was also observed after incubation of culture supernatants with osteoblasts during 8 hours, suggesting that the differences observed could be caused by a secreted molecule. Conclusions. Our results suggest that the mazEF system could be involved in S. aureus BJI physiopathology regulating cytotoxicity and persistence in osteoblasts. Our prospect is to identify the target of the mazF toxin which could be a therapeutic target

Intramuscular injections of botulinum neuro toxin A (BoNT-A) have been a cornerstone in the treatment of spasticity for the last two decades. In India, the treatment is now offered to children with spastic cerebral palsy (CP). However, despite its use, the evidence for its functional effects is limited and inconclusive. The objective of this study is to determine whether BoNT-A makes walking easier in children with CP. We hypothesize that injections with BoNT-A will not reduce energy cost during walking, improve walking capacity, reduce pain or improve self-perceived performance and satisfaction. Between the period of 2012 and 2014, 35 children with spastic CP less than 10 years of age were included. The patients were classified according to their gross motor function classification system (GMFCS) and their pre-and post-injection gait analysis were performed. Spasticity assessed by Modified Ashworth Score [MAS]. Trained parents were utilised for the post injection physiotherapy as these children will be more complaint to them. GMFCS and MAS scoring done every three months till one year follow up. Therapeutically, effect was found in 90% of the patients, an average duration of the medical effect was 6–12 months. The improvement in GMFC functional score in serial measurements was seen in these patients though some deterioration in spasticity scores at one year. Despite mild recurrence in spasticity, majority maintained independent (42%) or assisted ambulation (48%) at one year. No major side effects occurred. Botox may prove a useful adjuvant in conservative management of the spasticity of cerebral palsy. Apart from being very cost effective in these financially deprived populations, successful management with these injections may allow delay of surgical intervention until the child is older and at less risk of possible complications, including the need for repeated surgical procedures

Aim. The aim of this study was to gain insight into the in vivo expression of virulence and metabolic genes of Staphylococcus aureus in a prosthetic joint infection in a human subject. Method. Deep RNA sequencing (RNA-seq) was used for transcriptome profile of joint fluid obtained from a patient undergoing surgery due to acute S. aureus prosthetic joint infection. The S. aureus gene expression in the infection was compared with exponential culture of a S. aureus isolate obtained from the same sample using EdgeR. In addition, the genome of the isolate was sequenced on Miseq, assembled in CLC genomics workbench and annotated by MaGe. Moreover, using nuclear magnetic resonance (NMR) spectroscopy we analysed the metabolites in the joint fluid and in the culture supernatants to determine the biochemical composition of the environments. Results. Antibiotic susceptibility testing by disk diffusion (EUCAST) demonstrated that the strain was susceptible to β-lactams (penicillin and cefoxitin) and macrolides (erythromycin and roxitromycin). This was indirectly confirmed by the annotated genome, because of absence of known resistant genes. The patient showed no signs of improvement during 2-days treatment with antibiotics (different β-lactams and gentamicin) prior to the surgery. The RNA-seq data indicated that the strategy employed by S. aureus to survive and proliferate in the host during antibiotic treatment involved overexpression of various enzymes related to cell-wall synthesis and multidrug efflux pumps. Interestingly, these efflux pumps are only known to be related to fluoroquinolone resistance. Many of the genes encoding virulence factors were upregulated, including toxins and superantigen-like proteins, hemolysins, and immune evasion proteins. A number of chaperones and stress related genes were overexpressed indicating a stress response. Furthermore, the RNA-seq data provided clues of the potential major nutrient sources for the pathogen in vivo. Several amino acid degradation pathways were highly upregulated, e.g. arginine, histidine. Additional carbon sources included N-acetylneuraminate and purine/pyrimidine deoxyribonucleosides as indicated by the upregulation of the genes involved in the degradation pathways of these compounds and higher concentration of these substances in the joint fluid compared to culture supernatants. Conclusions. Our results show that the gene expression pattern of S. aureusin vivo is vastly different from that of an in vitro grown exponential culture, indicating that the pathogen adapts to host environmental conditions by altering gene expression. Finally our study emphasizes the importance of in vivo study in elucidating pathogenesis of S. aureus in prosthetic joint infections

There is no mathematical relationship between the internal diameter of the femoral metaphysis and diaphysis. Unless an infinite number of monolithic stems are available with variable metaphyseal and diaphyseal diameters, which is not economically possible, even in virgin cases, the surgeon has to decide if the stem is going to fit in the metaphysis or the diaphysis. It is not possible to match both. In revision cases with a hollowed out metaphysis, the situation is much worse. As it is obviously easier to fit the diaphysis, this is what stems such as the AML and Wagner stem have done. They completely ignore the metaphysis and obtain fixation in the diaphysis. This is all well and good, but it means that the proximal femur is unloaded, like an astronaut in space. While, there will be some recovery due to removal of the toxins and local muscle pull, it will be incomplete. Furthermore, should sepsis occur, one is faced with the horror of removing a distally fixed implant. Clearly, if proximal fixation, i.e. above the level of lesser trochanter could reliably be achieved, this would be preferable in terms of proximal loading leading to bone recovery and ease of removal should it be required. The only way that proximal loading can be achieved is if the metaphyseal and diaphyseal parts of the component can be varied infinitely. This clearly can only be achieved by using a modular stem. The concern with modularity always has been fretting at the sleeve-stem locking mechanism with release of metal ions. The stem, which I have been using for the last 25 years, is the SROM stem. Fretting and ion release had never been an issue. As the components are made of a relatively soft titanium alloy, it is likely that the sleeve and the stem cold weld, thus, eliminating any movement and eliminating friction. I have a follow-up of roughly 120 revision cases with a minimum follow-up of 5 years and a maximum follow-up of 22 years. I have no loosening in easy revision cases where a primary stem was used. I have had some loosenings in extremely difficult revision situations where a long bowed stem was required, but even then, the loosening rate is less than 3%. I use this stem in primary situations, i.e. in about 80% of all the primaries I have done. This means I have done roughly 1500 cases or more. Other than some late infections, I have never, ever had any stem loosening in a simple case. Obviously, I have had loosenings in some cases, where we have been doing fancy shortening or de-rotation osteotomies, but none in simple primary cases. I would, therefore, suggest that the surgeon, if he wishes to use this stem, please try it out on some simple primary cases. The ability to vary distal and proximal internal diameters and proximal geometry makes for easy surgery. I have been using this stem for 25 years and continue to use it in all my primary noncemented cases. I believe in the adage of “train hard and fight easy.” I think that surgeons should not get themselves into a situation where they are forced in a difficult case to use something they have never seen before

External fixation is widely used in orthopaedic and trauma surgery. Infections around pin or wire sites, which are usually localised, non-invasive, and are easily managed, are common. Occasionally, more serious invasive complications such as necrotising fasciitis (NF) and toxic shock syndrome (TSS) may occur.

We retrospectively reviewed all patients who underwent external fixation between 1997 and 2012 in our limb lengthening and reconstruction programme. A total of eight patients (seven female and one male) with a mean age of 20 years (5 to 45) in which pin/wire track infections became limb- or life-threatening were identified. Of these, four were due to TSS and four to NF. Their management is described. A satisfactory outcome was obtained with early diagnosis and aggressive medical and surgical treatment.

Clinicians caring for patients who have external fixation and in whom infection has developed should be aware of the possibility of these more serious complications. Early diagnosis and aggressive treatment are required in order to obtain a satisfactory outcome.

Cite this article: Bone Joint J 2015;97-B:1296–1300.