Chronic osteomyelitis caused by Achromobacter xylosoxidans following orthopaedic trauma: A case report and review of the literature

Chronic otorrhea and osteomyelitis of the external auditory canal by Achromobacter xylosoxidans: an uncommon diagnosis

PURPOSE

Achromobacter xylosoxidans is an emerging pathogen mainly associated with resistant nosocomial infections. This bacteria had been isolated in the ear together with other pathogens in cultures from patients with chronic otitis media, but it had never been reported as a cause of osteomyelitis of the external auditory canal.

CASE PRESENTATION

We present a unique case of a healthy 81-year-old woman who presented with left chronic otorrhea refractory to topical and oral antibiotic treatment. Otomicroscopy revealed an erythematous and exudative external auditory canal (EAC) with scant otorrhea. The tympanic membrane was intact, but an area of bone remodeling with a small cavity anterior and inferior to the bony tympanic frame was observed. Otic culture isolated multi-drug-resistant A. xylosoxidans, only sensitive to meropenem and cotrimoxazole. Temporal bone computed tomography showed an excavation of the floor of the EAC compatible with osteomyelitis. Targeted antibiotherapy for 12 weeks was conducted, with subsequent resolution of symptoms and no progression of the bone erosion.

CONCLUSIONS

Atypical pathogens such as A. xylosoxidans can be the cause of chronic otitis externa. Early diagnosis and specific antibiotherapy can prevent the development of further complications, such as osteomyelitis. In these cases, otic cultures play an essential role to identify the causal germ. This is the first case of EAC osteomyelitis due to A. xylosoxidans reported to date.

Pathological Thoracic Vertebral Fractures Secondary to Achromobacter denitrificans: A Case Report

Vertebral fractures remain a diagnostic challenge nowadays. The first and most common diagnosis needed to be ruled out is osteoporosis. Other diagnoses to rule out involve pathological fractures. Pathological fractures are a group of pathologies that result in a spine fracture as part of an underlying disease process that affects the spine. This group includes Paget's disease, tumors, osteomyelitis, and vertebral compression fractures. Fractures secondary to vertebral osteomyelitis are presented as collapsed vertebral bodies secondary to bone destruction and the formation of lytic lesions. Clinical presentation includes severe back pain refractory to analgesic therapy, persistent unexplained fever, and leukocytosis without any other obvious focus of infection. In cases like the one presented here, early biopsy and culture should be performed on every patient that fits these criteria. However, as it presents unspecific symptoms most of the time, it is not suspected, and therefore it is associated with high morbidity and mortality.

Immunoinformatic Approach to Contrive a Next Generation Multi-Epitope Vaccine Against Achromobacter xylosoxidans Infections

Achromobacter xylosoxidans, previously identified as Alcaligenes xylosoxidans, is a rod-shaped, flagellated, non-fermenting Gram-negative bacterium that has the ability to cause diverse infections in humans. As a part of its intrinsic resistance to different antibiotics, Achromobacter spp. is also increasingly becoming resistant to Carbapenems. Lack of knowledge regarding the pathogen’s clinical features has led to limited efforts to develop countermeasures against infection. The current study utilized an immunoinformatic method to map antigenic epitopes (Helper T cells, B-cell and Cytotoxic-T cells) to design a vaccine construct. We found that 20 different epitopes contribute significantly to immune response instigation that was further supported by physicochemical analysis and experimental viability. The safety profile of our vaccine was tested for antigenicity, allergenicity, and toxicity against all the identified epitopes before they were used as vaccine candidates. The disulfide engineering was carried out in an area of high mobility to increase the stability of vaccine proteins. In order to determine if the constructed vaccine is compatible with toll-like receptor, the binding affinity of vaccine was investigated via molecular docking approach. With the in silico expression in host cells and subsequent immune simulations, we were able to detect the induction of both arms of the immune response, i.e., humoral response and cytokine induced response. To demonstrate its safety and efficacy, further experimental research is necessary.