Bacterial osteomyelitis in veterinary orthopaedics: Pathophysiology, clinical presentation and advances in treatment across multiple species

Meat Inspection Decisions Regarding Pig Carcasses Affected by Osteomyelitis at the Slaughterhouse: From Etiopathogenesis to Total Condemnation Criteria

Osteomyelitis is a significant cause of total carcass condemnation in pigs at the slaughterhouse. The decision for total condemnation of a pig carcass for osteomyelitis is often based on traditional perceptions of the risk of pyaemia, leading to controversy among Official Veterinarians (OV) in the industry. This review aims to provide a more comprehensive understanding of the etiopathogenesis of osteomyelitis in pigs, the microorganisms involved, and the risk factors. It also highlights the urgent need for a more uniform method to evaluate osteomyelitis cases, which could significantly reduce economic losses in the industry. Lesions originating from tail-biting, tail docking, castration, teeth resection, and raw management are described as risk factors for osteomyelitis. Osteomyelitis is caused by the entry of pathogens into the animal's bloodstream through an open wound. Trueperella monocytogenes, Staphylococcus aureus, and Streptococcus spp. are the most described pathogens. At slaughter, OVs condemn carcasses with osteomyelitis due to pyaemia. Signs of acute disease are essential to identify pyaemia cases. In chronic cases, total carcass condemnation can be avoided depending on the number of lesions and vertebrae affected. A clear overall image of the problem would help authorities in various countries adopt a more homogenous approach.

Integrating multi-wet laboratory diagnostics to study staphylococci in animals in Uganda

BACKGROUND

Several diagnostic environments in Uganda lack real-time, robust and high-throughput technologies for comprehensive typing of microbes, which is a setback to infectious disease surveillance. This study combined various wet laboratory diagnostics to understand the epidemiology of pathogenic staphylococci isolated from animals in Uganda and the implications for global health security priorities.

METHODS

A retrospective study was conducted employing records and pathogenic staphylococci (from animals) archived at the Central Diagnostic Laboratory (CDL), Makerere University, Uganda, between January 2012 and December 2019. The bacteria were speciated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and tested for virulence factors [beta lactamases, lecithinase, deoxyribonuclease (DNase), haemolysins] and resistance to ten antimicrobials of clinical and veterinary relevance. Tetracycline and methicillin resistance genes were also tested.

RESULTS

The prevalent diseases were mastitis in cattle and skin infections in dogs. Of the 111 staphylococci tested by MALDI-TOF MS, 79 (71.2%) were Staphylococcus aureus, 27 (24.3%) were Staphylococcus pseudintermedius and 5 (4.5%) were Staphylococcus schleiferi. All these strains expressed haemolysins. The prevalence of strains with lecithinase, penicillinase, cephalosporinase and DNase was 35.9% (14/39), 89.7% (35/39), 0.0% (0/39) and 87.2% (34/39), respectively. Staphylococci were primarily resistant to early penicillins (over 80%), tetracycline (57.7%), and chloramphenicol (46.2%). Minimal resistance was noted with cloxacillin (0.0%), ciprofloxacin (9.6%), and cefoxitin (3.8%). The prevalence of multidrug resistance (MDR) was 78.8% for general staphylococci, 82.2% for S. aureus, 73.1% for S. pseudintermedius, and 60.0% for S. schleiferi. Multidrug resistant staphylococci were significantly more prevalent in the cattle isolates than in the dog isolates (P < 0.05). The prevalence of methicillin-resistant staphylococci (MRS) tested by resistance to cefoxitin and mecA carriage was 3.8%. These four strains were all isolated from dog skin infections. The tetK gene was the most predominant (35.4%), followed by tetM (25.0%).

CONCLUSION

In resource-constrained settings, the approach of integrated diagnostics promises sustainable disease surveillance and the addressing of current capacity gaps. The emergence of MRS (zoonotic bacteria) in companion animals creates a likelihood of reduced treatment options for related human infections, a threat to global health.

Mechanobiology of bacterial biofilms: Implications for orthopedic infection

Postoperative bacterial infections are prevalent complications in both human and veterinary orthopedic surgery, particularly when a biofilm develops. These infections often result in delayed healing, early revision, permanent functional loss, and, in severe cases, amputation. The diagnosis and treatment pose significant challenges, and bacterial biofilm further amplifies the therapeutic difficulty as it confers protection against the host immune system and against antibiotics which are usually administered as a first-line therapeutic option. However, the inappropriate use of antibiotics has led to the emergence of numerous multidrug-resistant organisms, which largely compromise the already imperfect treatment efficiency. In this context, the study of bacterial biofilm formation allows to better target antibiotic use and to evaluate alternative therapeutic strategies. Exploration of the roles played by mechanical factors on biofilm development is of particular interest, especially because cartilage and bone tissues are reactive environments that are subjected to mechanical load. This review delves into the current landscape of biofilm mechanobiology, exploring the role of mechanical factors on biofilm development through a multiscale prism starting from bacterial microscopic scale to reach biofilm mesoscopic size and finally the macroscopic scale of the fracture site or bone-implant interface.

Effects of storage up to 1 year on the in vitro antimicrobial activity of preformulated antibiotic-impregnated calcium sulfate beads

OBJECTIVE

To compare antimicrobial activity as demonstrated by the zone of inhibition (ZOI) produced by antibiotic-impregnated calcium sulfate (CaSO4) beads after storage for 0, 3, 6, 9, and 12 months.

STUDY DESIGN

Controlled laboratory study.

SAMPLE POPULATION

Three-millimeter diameter CaSO4 beads impregnated with vancomycin (125 mg/mL), or amikacin (250 mg/mL), or without antibiotic (control).

METHODS

Calcium sulfate beads were created at the onset of the study. Individual beads were separated in sterile containers and stored in a closed cabinet at room temperature and humidity for 0, 3, 6, 9, or 12 months until testing. The ZOI against methicillin-resistant Staphylococcus pseudintermedius, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa was recorded with serial replating on a fresh lawn of bacteria every 24 h until beads failed to produce a ZOI. The ZOIs and their changes were compared with mixed-effects linear models. Eluted concentrations of vancomycin measured with high-performance liquid chromatography were reported.

RESULTS

At 24 h, ZOIs were comparable regardless of time since formulation, except vancomycin against P. aeruginosa, which failed to generate a ZOI. The daily changes of ZOI and duration of activity of antibiotics did not vary between storage length (p > .05). There was no consistent change in eluted drug concentration between storage length of beads.

CONCLUSION

Light protected storage at room temperature for up to 12 months did not impair the in vitro activity of antibiotic-impregnated CaSO4 beads, as demonstrated through ZOIs.

CLINICAL SIGNIFICANCE

When stored correctly, antibiotic-impregnated CaSO4 beads can be used at least up to 12 months after formulation.

Osteomyelitis in Pig Carcasses at a Portuguese Slaughterhouse: Association with Tail-Biting and Teeth Resection

Osteomyelitis is the leading cause of total carcass condemnation in finishing pigs in Portugal, causing significant economic losses in swine production. The present study sought to determine a possible link between osteomyelitis in pig carcasses, pre-slaughter factors, and concomitant post-mortem inspection findings. For this purpose, meat inspection data were collected from 100,489 finishing pigs slaughtered in a northern Portuguese abattoir. Information regarding total carcass condemnation, slaughter season, origin, sex, tail-biting lesions, and husbandry invasive procedures (tail docking and teeth resection) was collected. The main cause of total carcass condemnation was osteomyelitis (61.03%). A total of 36.16% of osteomyelitis cases were present in the anterior region and 52.20% in the posterior region. In the anterior region, 94.78% of osteomyelitis cases were in the mandibular bone. Pigs with clipped teeth and carcasses with pleurisies were associated with a higher occurrence of osteomyelitis (p = 0.00262 and p < 0.0001, respectively). Second- and third-grade tail-biting lesions were also linked to a higher occurrence of osteomyelitis (p = 0.00128 and p < 0.0001, respectively). Slaughter inspection and monitoring procedures should be revised to better assess welfare factors and correlate management practices with the occurrence of osteomyelitis in pig carcasses.

Facile fabrication of linezolid/strontium coated hydroxyapatite/graphene oxide nanocomposite for osteoporotic bone defect

Hydroxyapatite (HAp) coatings currently have limited therapeutic applications because they lack anti-infection, osteoinductivity, and poor mechanical characteristics. On the titanium substrate, electrochemical deposition (ECD) was used to construct the strontium (Sr)-featuring hydroxyapatite (HAp)/graphene oxides (GO)/linezolid (LZ) nanomaterial coated with antibacterial and drug delivery properties. The newly fabricated nanomaterials were confirmed by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis and morphological features were examined by scanning electron microscope (SEM) analysis. The results reveal multiple nucleation sites for SrHAp/GO/LZ composite coatings due to oxygen-comprising moieties on the 2D surface of GO. It was shown to be favorable for osteoblast proliferation and differentiation. The elastic modulus and hardness of LZ nanocomposite with SrHAp/GO/LZ coatings were increased by 67 % and 121 %, respectively. An initial 5 h burst of LZ release from the SrHAp/GO/LZ coating was followed by 14 h of gradual release, owing to LZ's physical and chemical adsorption. The SrHAp/GO/LZ coating effectively inhibited both S. epidermidis and S. aureus, and the inhibition lasted for three days, as demonstrated by the inhibition zone and colony count assays. When MG-63 cells are coated with SrHAp/GO/LZ composite coating, their adhesion, proliferation, and differentiation greatly improve when coated with pure titanium. A novel surface engineering nanomaterial for treating and preventing osteoporotic bone defects, SrHAp/GO/LZ, was shown to have high mechanical characteristics, superior antibacterial abilities, and osteoinductivity.

Microbial Colonization of Explants after Osteosynthesis in Small Animals: Incidence and Influencing Factors

Despite recent advancements in antibiotics, hygienic measures, and peri-operative systemic antibiotics, post-operative infections in osteosynthesis remain prevalent and continue to be among the most common surgical complications, leading to delayed fracture healing, osteomyelitis, implant loosening, and loss of function. Osteosynthesis implants are routinely utilized in veterinary medicine and the current study investigates the microbial colonization of implants following osteosynthesis in small animals, along with its incidence and influencing factors. The results are analyzed in regard to correlations between infection, patient, disease progression, and radiographic images, as well as other factors that may promote infection. Seventy-one explants from sixty-five patients were examined and evaluated for microbial colonization. Factors like body weight and age, location and type of plate and additional injuries like lung lesions, the surgeon's experience, or the number of people present during the surgical procedure seem to influence the development of an infection. Of the animals, 60% showed osteolytic changes and 73.3% of those with dysfunctional mobility had an implant infection. Microorganisms were detected in almost 50% of the explants, but a clinically relevant infection was only present in five patients (7.3%), suggesting that the presence of microorganisms on an implant does not necessarily lead to treatment complications.

Reconstructive surgery with an autologous bone graft in a dog with presumptive chronic non-bacterial osteomyelitis

A 15-year-old Cocker Spaniel was referred to for the evaluation of left forelimb lameness. Radiographic and computed tomography examinations revealed osteolysis of the proximal left third, fourth and fifth metacarpal bones and pathological fractures of the proximal left fourth metacarpal bone. Histopathological examination via bone biopsy did not provide a definitive diagnosis, and the owner elected limb-sparing surgery. The fourth metacarpal bone and digits were amputated. Subsequently, autologous bone grafts were performed on the lytic area of the third and fifth metacarpal bones. The dog showed improvement in gait 7 weeks after reconstructive surgery. Chronic non-bacterial osteomyelitis (CNO) was diagnosed by exclusion. To the best of our knowledge, CNO has not been previously reported in dogs.

Osteomyelitis by Microsporum canis and Staphylococcus spp. in cat (Felis catus) - case report

BACKGROUND

Staphylococcus spp and Microsporum canis are zoonotic microorganisms which can cause infections and systemic diseases. The bone infection is usually caused by invasion of pathogen through the hematologic route. Mixed osteomyelitis caused by bacteria and fungi is rare, and to date, there have been no reports of mixed osteomyelitis with Staphylococcus spp. and Microsporum canis.

CASE PRESENTATION

This essay reports an atypical presentation of mixed osteomyelitis (Staphylococcus spp. and Microsporum canis) in a domestic cat. A 15-month-old female Persian cat was presented to a veterinary service; the main complaint was the appearance of a nodule in the mandibular ventral rostral region. A radiographic exam performed on the animal showed proliferative and osteolytic bone lesions. The patient was submitted to a biopsy for histopathological evaluation, along with bacterial and fungal cultures. Results showed mixed osteomyelitis by Staphylococcus spp. and Microsporum canis. Microbial Sensitivity Test was performed to choose a more suitable treatment. Two surgical procedures were executed to resect and curette the lesion, and treatments with anti-inflammatory, antibiotic, and antifungal drugs were established, showing a positive clinical evolution. After 8 months of treatment, the patient's owner moved to a different city, and the animal was seen by other veterinarians, who followed along with the same treatment. However, due to complications and a diminishing quality of life over 4 years of diagnosis, the patient was euthanized.

CONCLUSION

Given the above, mixed osteomyelitis is difficult to treat and can cause losses of life quality resulting death, especially in infections where M. canis is the agent causing the disease. Bacterial osteomyelitis is more frequently reported. But the lack of investigation of microorganisms other than bacteria, such as fungal cases, may imply in underdiagnosed cases. Treatment of osteomyelitis can be difficult considering the difficulties in isolating the pathological agent, resistance to the drug used, prolonged treatment time, and cost.

Biofilm formation by Staphylococcus pseudintermedius on titanium implants

Osteomyelitis often involves Staphylococcus spp. as the isolated genus in domestic animal cases. Implant-related infections, frequently associated with biofilm-forming microorganisms like staphylococci species, necessitate careful material selection. This study assessed biofilm formation by Staphylococcus pseudintermedius on titanium nuts used in veterinary orthopaedic surgery. Biofilm quantification employed safranin staining and spectrophotometric measurement, while bacterial counts were determined in colony-forming units (CFU). Scanning Electron Microscopy (SEM) evaluated the biofilm morphology on the surface of titanium nuts. All samples had CFU counts. Absorbance values that evidence biofilm formation were observed in seven of the eight samples tested. SEM images revealed robust bacterial colonization, and significant extracellular polymeric substance production, and the negative control displayed surface irregularities on the nut. Whole genome sequencing revealed accessory Gene Regulator (agr) type III in six samples, agr IV and agr II in two each. Genes encoding hlb, luk-S, luk-F, siet, se_int, and the icaADCB operon were identified in all sequenced samples. Other exfoliative toxins were absent. Biofilm formation by S. pseudintermedius was detected in all samples, indicating the susceptibility of orthopaedic titanium alloys to adhesion and biofilm formation by veterinary species. The biofilm formation capacity raises concerns about potential post-surgical complications and associated costs.

Vertebral Osteosarcoma in Two Cats-Diagnosis, Treatment, and Outcome

In this case report, we describe the diagnosis, treatment, and outcome of two feline cases of vertebral osteosarcoma. Case 1: A 6-year-old female neutered domestic longhaired cat was presented with progressive paraparesis, ataxia, and spinal hyperesthesia. MRI of the thoracolumbar spinal cord and vertebral column revealed a strongly contrast-enhancing mass lesion originating from the dorsal lamina and spinous process of T13. The lesion caused extradural compression of the spinal cord. Surgical debulking was performed, and the histopathological evaluation of surgical biopsies was consistent with vertebral osteosarcoma. The cat was paraplegic with intact nociception post-surgery. Subsequently, the cat recovered ambulation while remaining mildly ataxic and paraparetic at long-term follow-up. Post-operative chemotherapy was started with doxorubicin. CT scans at 2, 4, 9, 13, and 20 months post-surgery showed no signs of local recurrence or metastasis. Case 2: A 15.5-year-old male neutered domestic shorthaired cat was presented with progressive paraparesis, tail paresis, and spinal hyperesthesia. Radiographs and CT scan of the lumbar vertebral column showed a large mass originating from the dorsal lamina and spinous process of L6, suggestive of neoplasia, with severe compression of the spinal cord. Surgical debulking was performed, and the histopathological evaluation was consistent with vertebral osteosarcoma. Post-operative chemotherapy was started with doxorubicin. Seven months post-surgery, the patient was neurologically normal with no signs of metastatic disease. This case report highlights the possibility of good outcomes after the surgical treatment of feline vertebral osteosarcoma supplemented with post-surgical chemotherapy.

Anti-Staphylococcal Activity of Ligilactobacillus animalis SWLA-1 and Its Supernatant against Multidrug-Resistant Staphylococcus pseudintermedius in Novel Rat Model of Acute Osteomyelitis

Osteomyelitis caused by staphylococcal infection is a serious complication of orthopedic surgery. Staphylococcus pseudintermedius is the main causative agent of osteomyelitis in veterinary medicine. Methicillin-resistant S. pseudintermedius (MRSP) has been reported in companion animals, especially dogs. Multidrug-resistant S. pseudintermedius is an emerging pathogen and has acquired antibiotic resistance against various commercial antimicrobial agents. New antimicrobial compounds are urgently needed to address antibiotic resistance, and the development of novel agents has become an international research hotspot in recent decades. Antimicrobial compounds derived from probiotics, such as bacteriocins, are promising alternatives to classical antibiotics. In this study, the antibacterial activities of Ligilactobacillus animalis SWLA-1 and its concentrated cell-free supernatant (CCFS) were evaluated in vitro and in vivo. The CCFS of this bacterium showed no toxicity against osteoblast and myoblast cells in vitro, while significantly inhibiting the multidrug-resistant S. pseudintermedius KUVM1701GC strain in a newly established rat model. The CCFS significantly inhibited multidrug-resistant staphylococci both in vitro and in vivo. This suggests that CCFS derived from L. animalis SWLA-1 has potential as an alternative to classic antibiotics for staphylococcal infections in dogs.

Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine

Indications for implant removal after fracture healing are still under debate in both human and veterinary medicine. Although hardware removal is a common procedure, it should not be undertaken lightly. Intra and post-operative complications are common and a thorough evaluation of the risks and benefits should be performed. This review aimed to collect and summarise published data on the indications for implant removal in small animals, compare the collected data with human and equine medicine, and investigate the existence of guidelines for this purpose. There is no international consensual agreement for implant removal after fracture healing, neither in small animals nor in human orthopaedics. Decision-making processes are still controversial in some scenarios, thus clear evidence-based protocols for implant removal are needed.

Osteomyelitis caused by Aspergillus terreus complex in a dog: a case report

BACKGROUND

In dogs, the most frequently reported mycosis associated with Aspergillus spp. are respiratory infections. Systemic aspergillosis is uncommon, with reported cases been associated with several Aspergillus species. Aspergillus terreus species complex are ubiquitous organisms, unfrequently associated with local or systemic disease in animals and humans, and treatment of osteomyelitis caused by this species is usually unfavorable.

CASE PRESENTATION

This case report describes the case of a 5-year-old dog, referred to the Veterinary Hospital of the Faculty of Veterinary Medicine of the University of Lisbon, Portugal, with a history of lameness of the right thoracic limb. Radiographs and CT scan revealed two different lesions on right humerus and radio, which were biopsied. The samples collected were submitted to cytological and histopathological evaluation and bacterial and mycological culture. Environmental samples, including of the surgery room and of the biopsy needle were also evaluated for the presence of fungi. Regarding biopsy samples, bacterial culture was negative, but mycological analysis originated a pure culture of a fungal species later identified as Aspergillus terreus by Sanger sequencing. Results were compatible with histopathologic examination, which revealed periosteal reaction and invasion of hyphae elements. Also, mycological analysis of both environmental samples evaluated were negative. The virulence profile of the fungal isolate was phenotypically characterized using specific media, allowing to reveal its ability to produce several enzymes involved in its pathogenicity, namely lipase, hemolysin and DNAse, corresponding to a Virulence Index (V. Index.) of 0.43. The patient was submitted to itraconazole therapy for 8 weeks. After 3 weeks, the patient showed significant clinical improvement, and after 6 weeks no radiographic signs were observed.

CONCLUSIONS

Antifungal therapy with itraconazole can contribute to the remission of canine infections promoted by Aspergillus terreus complex with a relevant V. Index.

The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections

Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.

Microbiological aspects of osteomyelitis in veterinary medicine: drawing parallels to the infection in human medicine

Osteomyelitis is a challenging infectious disease affecting humans and animals. It is difficult to diagnose because, in many cases, symptoms are non-specific and, for example in implant-related cases, can appear long time after surgery. In addition to this, it is also difficult to treat due to the need to find the appropriate antibiotic regime and delivery system to reach the site of infection and to avoid development of bacterial resistance. The central purpose of this review is to compare the microbiological aspects of osteomyelitis in human and veterinary medicine, with the aim of improving the microbiological diagnosis and treatment of this infection in animals. Furthermore, the study of osteomyelitis in animals may help to improve the development of animal models for testing new treatments in humans. Host factors and underlying conditions have been studied mainly in humans, although aspects as immunodeficiency have been described in some veterinary cases. Even when Staphylococcus aureus is still considered the most prevalent causing microorganism, this prevalence should be reviewed using molecular diagnostic techniques, and this could affect treatment options. New approaches to treatment include local delivery of antibiotics using different biomaterials, antimicrobial photodynamic therapy, and new antimicrobial compounds. We would like to remark the need of large, high-quality clinical trials and of the development of guides for the diagnosis and treatment of osteomyelitis in different animal species.

Implantable drug delivery systems for the treatment of osteomyelitis

Osteomyelitis is an infection of the bone tissue and bone marrow which is becoming increasingly difficult to treat due to the infection causing pathogens associated. Staphylococcus aureus is one of the main bacteria that causes this infection, which has a broad spectrum of antibiotic resistance making it extremely difficult to treat. Conventional metal implants used in orthopaedic applications often have the drawback of implant induced osteomyelitis as well as the requirement of a second surgery to remove the implant once it is no longer required. Recently, attention has been focused on the design and fabrication of biodegradable implants for the treatment of bone infection. The main benefit of biodegradable implants over polymethylmethacrylate (PMMA) based non-degradable systems is that they do not require a second surgery for removal and so making degradable implants safer and easier to use. The main purpose of a biodegradable implant is to provide the necessary support and conductivity to allow the bone to regenerate whilst themselves degrading at a rate that is compatible with the rate of formation of new bone. They must be highly biocompatible to ensure there is no inflammation or irritation within the surrounding tissue. During this review, the latest research into antibiotic loaded biodegradable implants will be explored. Their benefits and drawbacks will be compared with those non-degradable PMMA beads, which is the stable material used within antibiotic loaded implants. Biodegradable implants most frequently used are based on biodegradable natural and synthetic polymers. Implants can take the form of many different structures; the most commonly fabricated structure is a scaffold. Other structures that will be explored within this review are hydrogels, nanoparticles and surface coatings, all with their own benefits/drawbacks.

Osteomyelitis associated with Bartonella henselae infection in a young cat

Case summary

A 1-year-old male intact domestic shorthair cat was evaluated for acute onset non-weightbearing left forelimb lameness and generalized peripheral lymphadenopathy. CT identified a monostotic aggressive bone lesion with an incomplete fracture of the left radial metaphysis. Bone aspirates yielded osteoblasts with minimal nuclear atypia. Abdominal ultrasound revealed a nodular spleen and lymphadenopathy; cytologically, both contained lymphoid hyperplasia. A urine histoplasma antigen test was negative. Bartonella henselae and Mycoplasma haemominutum DNA was amplified by PCR from peripheral blood. Indirect immunofluorescence documented strong B henselae immunoreactivity, with lower Bartonella vinsonii subspecies berkhoffii and Bartonella koehlerae antibody titers. After the administration of doxycycline and pradofloxacin for suspected Bartonella-induced osteomyelitis, lameness resolved rapidly. Six-week post-treatment radiographs identified healing of the affected bone, and Bartonella species enrichment blood culture was negative. B henselae antibody titers decreased four-fold over a year, supporting seroreversion.

Relevance and novel information

B henselae is a flea-transmitted, host-adapted species, not previously implicated as a cause of osteomyelitis in cats. B henselae subclinical bacteremia is highly prevalent among cats; however, bacteremia has been associated with lymphadenopathy and febrile illness in cats. This report describes a unique clinical presentation in association with B henselae infection in a cat.

[Severe chronic osteomyelitis of the os ileum in an alpaca - Diagnostic and pathological findings]

A 5.5-year-old alpaca mare was referred to the University Clinic for Ruminants due to a lameness in the right hind limb. Six months prior to presentation, the mare had been treated with systemic antibiotics resulting in resolution of the initial lameness. At the time there had been no indication of an inciting trauma. Clinical examination revealed an approx. 2 × 2 cm large, fluctuating, neither excessively warm nor painful mass caudal to the right tuber coxae fixed to the underlying tissue. In addition, a moderate, mixed lameness with a predominant proportion of the swinging leg component was present in the right hind limb. Subsequently, sonographic examination of the right gluteal region was performed, revealing severe alterations of bone contour in the area of the right hip joint. Radiographic assessment of the pelvis was carried out for further clarification. Based on the clinical finding of a fistula in the right gluteal region as well as the results of the radiologic examination, a long-standing infected fracture of the right iliac bone accompanied by high-degree, irregularly calcified callus formation and low to moderate osteomyelitis in the fracture area was diagnosed. The patient was euthanized in consequence of the grave prognosis. Computed tomographic examination of the pelvis and the lumbar spine in the L3-L6 area was undertaken in order to further document the extent of the pathological changes. For final clarification, patho-histological examination as well as a microbiologic analysis of the abscess exudate were performed.The presented case shows the importance of clinical as well as orthopedic examinations, as the individual animal frequently only exhibits minimal clinical signs despite the presence of severe changes.

Staphylococcus aureus and Acinetobacter baumannii Inhibit Osseointegration of Orthopedic Implants

Bacterial infections routinely cause inflammation and thereby impair osseointegration of orthopedic implants. Acinetobacter spp., which cause osteomyelitis following trauma, on or off the battlefield, were, however, reported to cause neither osteomyelitis nor osteolysis in rodents. We therefore compared the effects of Acinetobacter strain M2 to those of Staphylococcus aureus in a murine implant infection model. Sterile implants and implants with adherent bacteria were inserted in the femur of mice. Bacterial burden, levels of proinflammatory cytokines, and osseointegration were measured. All infections were localized to the implant site. Infection with either S. aureus or Acinetobacter strain M2 increased the levels of proinflammatory cytokines and the chemokine CCL2 in the surrounding femurs, inhibited bone formation around the implant, and caused loss of the surrounding cortical bone, leading to decreases in both histomorphometric and biomechanical measures of osseointegration. Genetic deletion of TLR2 and TLR4 from the mice partially reduced the effects of Acinetobacter strain M2 on osseointegration but did not alter the effects of S. aureus. This is the first report that Acinetobacter spp. impair osseointegration of orthopedic implants in mice, and the murine model developed for this study will be useful for future efforts to clarify the mechanism of implant failure due to Acinetobacter spp. and to assess novel diagnostic tools or therapeutic agents.

Chondroblastic Osteosarcoma Associated with Previous Chronic Osteomyelitis Caused by Serratia liquefaciens in a German Shepherd Dog

Development of bone tumors as a result of chronic osteomyelitis represents a relatively rare and late complication in humans and animals. We described a malignant transformation (chondroblastic osteosarcoma) in a 7-year-old German shepherd with a history of polyostotic osteomyelitis caused by Serratia liquefaciens when the dog was 15 months old. The tumor developed in the right humeral diaphysis, one of the sites of polyostotic osteomyelitis. To the best of our knowledge this is the first report of polyostotic osteomyelitis caused by Serratia liquefaciens in dogs.

Osteomyelitis in cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) hospitalized for rehabilitation: 25 cases (2008-2018)

OBJECTIVE

To characterize osteolytic lesions in cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) hospitalized for rehabilitation and describe methods used for the management of such lesions.

ANIMALS

25 stranded, cold-stunned Kemp's ridley sea turtles hospitalized between 2008 and 2018.

PROCEDURES

Medical records of sea turtles with a diagnosis of osteolytic lesions were reviewed retrospectively to obtain the date of diagnosis, clinical signs, radiographic findings, microbial culture results, hematologic and plasma biochemical data, cytologic and histologic findings, antimicrobial history, time to first negative culture result, treatment duration, and outcome.

RESULTS

Lesions were identified radiographically a median of 50 days after admission and were located within epiphyses or metaphyses of various appendicular joints. Lesions were associated with periarticular swelling (n = 24), lameness (16), lethargy (2), and hyporexia (2). Bacterial culture yielded growth of single organisms (n = 16), multiple organisms (2), or no growth (6). Significant differences in hematologic and biochemical data were detected between the times of diagnosis and convalescence. Cytologic and histologic findings characterized the lesions as osteomyelitis leading to septic arthritis. Sixteen sea turtles were managed medically, and 8 were managed medically and surgically. Surgery resulted in rapid improvement in joint mobility and overall clinical status. Most (22/25 [88%]) sea turtles survived and were released after long-term management.

CONCLUSIONS AND CLINICAL RELEVANCE

During rehabilitation, cold-stunned Kemp's ridley sea turtles may be affected by osteomyelitis. Medical management based on antimicrobial susceptibility testing was effective for most turtles. Long term management efforts in turtles are justified by high survival rate.

A case of canine Salmonella spp. osteomyelitis with secondary fracture following dog bite

An immature canine was attacked by another dog in a kennel facility and sustained multiple wounds to the lateral right forelimb and cranial right lateral thoracic region. General surgical and antimicrobial therapies were instituted immediately. The patient battled with recurrent infections and subsequent delayed healing. After approximately 35 days from the initial injury, the patient became acutely lame and febrile. The persistently open wounds were cultured and returned positive for Salmonella spp. Within the following days, the patient became painful, and the lameness progressed significantly. Radiographs confirmed pathologic humeral fracture, and the patient was referred for specialty evaluation. Zoonotic preventative protocols were adopted at the specialty facility upon arrival. Complete forequarter limb amputation was curative in this patient.

Effect of implants of hydroxyapatite with tricalcium phosphates alloyed with Si on histomorphological and biochemical parameters in cases of bone defects of rabbits

Complex comminuted fractures are accompanied by development of bone defects and loss of reparative potential of the bone tissue in the region of the trauma. This brings the necessity of using implants with optimum osteoconductive and osteointegration properties. The objective of the study was determining the condition of biochemical bone markers and peculiarities of histomorphological changes under the influence of ceramic hydroxyapatite (HA) implants with various physical-chemical properties in the conditions of diaphyseal bone defects in rabbits. We composed control and experimental groups of rabbits with 10 individuals in each with diaphyseal bone defects (3 mm) of the radial bones formed under general anesthesia. In one experimental group, they were filled with granules of hydroxyapatite with α-tricalcium phosphate, and in the second group – with β-tricalcium phosphate, alloyed with Si. In the control rabbits, the defects healed under a blood clot. Blood was analyzed on the 3rd, 7th, 14th, 21st and 42nd days, and as reference we used biochemical parameters of blood of clinically healthy rabbits (n = 10). Bone biopsied materials were taken on days 21–42 under general anesthesia. When using hydroxyapatite with β-tricalcium phosphate, alloyed with Si, we determined early intensification of the levels of nitrogen oxide, angiogenesis and development of bone regenerate in conditions of shortening of inflammatory resorption phase, which was verified according to the level of tartrate-resistant acid phosphatase. According to the level of bone isoenzyme of alkaline phosphatase in the blood serum of animals of the control group, the reparative osteogenesis developed slowly and peaked on day 42, whereas in animals implanted with α-tricalcium phosphate, its development peaked peaked on days 14–42, and when using Si-alloy – on days 7–14. Histomorphologically, on the 21st day, in the case of replacement of bone defect with hydroxyapatite with α-tricalcium phosphate, coarse-fibered type of bone regenerate developed with no dense contact with the elements of the regenerate, while spongy bone trabeculae occurred when hydroxyapatite was applied with β-tricalcium phosphate alloyed with Si, and the control rabbits were observed to be in the stage of cartilaginous callus. On the 42nd day, under the influence of implants of hydroxyapatite with α-tricalcium phosphate, the spongy bone tissue transformed into compact tissue with further mineralization. With implants alloyed with Si, there occurred compact bone tissue, and bone regenerates of the control animals were regions of coarse-fibered and spongy bone tissue without dense contact with the parent bone. This study revealed that hydroxyapatite with β-tricalcium phosphate alloyed with Si had notable osteoinductive and osteointegrating properties, as indicated by early angiogenesis and osteoblast reaction, positive dynamics of the marker biochemical parameters with faster and better development of bone regenerate as spongy bone trabeculae.

Therapeutic potential of dalbavancin in a rat model of methicillin-resistant Staphylococcus aureus (MRSA)-osteomyelitis

Bacterial osteomyelitis is a major clinical challenge in human and veterinary patients. This infection is an infrequent but feared complication of orthopedic surgery and is mainly caused by methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to evaluate the efficacy of dalbavancin (dosed for either 7 or 14 days) in an MRSA-osteomyelitis tibial bone model. A total of 39 rats were included in the study. All animals received an inoculum of a clinical strain of MRSA (10⁶ colony-forming units [CFU]) injected into the proximal tibia under general anesthesia. Dalbavancin was injected intraperitoneally for 7 or 14 days in 13 animals each; the remaining 13 animals received saline solution. After treatment, the animals were sacrificed. Infected tibiae were recovered for histological evaluation and microbiological analysis (MRSA count per gram of bone). Rats that received dalbavancin showed a statistically significant reduction of MRSA counts compared with the control group: median 0 CFU/g bone (14 days of dalbavancin) vs. 70 CFU/g bone (7 days of dalbavancin) and 1600 CFU/g bone (control). Histological evaluation showed typical signs of osteomyelitis in the control group, whereas there were no signs of bone infection in 92% of the rats that received 14 days of dalbavancin. According to this model, dalbavancin seems to have good efficacy for treating serious Gram-positive bone infections, including those caused by MRSA.