The impact of antibiotic pre-treatment on diagnostic yield of CT-guided biopsy for spondylodiscitis: A multi-centre retrospective study and meta-analysis.

INTRODUCTION: Patients with suspected spondylodiscitis often undergo CT-guided biopsy to identify a causative microbiological organism. Antibiotic pre-treatment has been postulated as a cause for a negative biopsy, although previous clinical studies have been heterogenous with a meta-analysis suggesting no effect. The aim of this study was to assess the impact of antibiotic pre-treatment on microbiological yield. METHODS: Retrospective review of consecutive adult patients undergoing CT-guided biopsy for suspected spondylodiscitis in two tertiary centres between 2010 and 2016. Demographic, procedural and clinical data were collected. Antibiotic pre-treatment was ascertained from patient drug charts. RESULTS: Over the 6-year period, 104 biopsies in 104 patients were included. 51% had a positive microbiological yield at CT-guided biopsy, with the most common isolated organism being Staphylococcus aureus (10.6%). Over two thirds of patients (69.3%) were off antibiotics at time of biopsy. There was no significant difference in microbiological yield in those patients on versus off antibiotics (48.2% vs 54.2%, P = 0.55). 10.6% patients had a final diagnosis of Mycobacterium tuberculosis spondylodiscitis, and this organism was significantly associated with a positive microbiological yield (90.9% vs 46.2%, P = 0.01). There was an inverse association between the presence of fever and sepsis with positive microbiological yield. CONCLUSIONS: CT-guided biopsy in suspected spondylodiscitis obtains a positive microbiological yield in about half of patients. This was significantly higher in patients diagnosed with tuberculosis spondylodiscitis, but there was no significant difference with antibiotic pre-treatment. Therefore, antibiotic pre-treatment should not preclude clinicians from pursuing a microbiological sample through CT-guided biopsy.

Five-year experience of corneal scrapes at Wellington Eye Department, New Zealand.

AIM: To determine the causative organisms of bacterial keratitis in Wellington and to identify the antibiotic sensitivities of each bacterium isolated. These results will then be compared with certain patient characteristics and clinical outcomes. METHODS: Corneal scrapes collected between 2001 and 2005 were retrospectively analysed and collated on a database. Corneal scrapes were collected by an ophthalmologist and processed by trained microbiological staff. RESULTS: 34 scrapes were collected; there was a positive Gram-stain in 38% of cases. A positive culture was obtained in 85% of scrapes. The commonest Gram-negative organism was Moraxella spp. (12.5%). The commonest Gram-positive organism was coagulase-negative Staphylococci (25%). The Gram-negative and Gram-positive bacteria were all sensitive to chloramphenicol. Ocular surface disease was the most common risk factor. CONCLUSION: Our study shows similarities and differences with other ophthalmology centres around the World, this emphasises the recognised regional variation of bacterial keratitis. The two most important points to be taken from our results are: an accurate database for recording corneal scrape details and a protocol for testing antibiotic sensitivities and resistance needs to be established in Wellington; and a future study needs to be carried out on the next five years of corneal scrapes.