BORS-OP1: IS THERE A BENEFIT FROM IMMEDIATE BROTH CULTURE OF INTRA-OPERATIVE MUSCULOSKELETAL SPECIMENS?

Abstract

The diagnosis of musculoskeletal infection is an ongoing problem. Multiple specimens and histology peri-operatively have been used to increase the accuracy of the diagnosis. However, to determine antibiotic resistance profiling it is essential to grow bacteria from the patient. The aim of this prospective study was to evaluate whether there is an increase in the rate of isolation of micro-organisms from musculoskeletal tissue samples sent directly in broth culture or whether there is an over-diagnosis due to false positive contaminants.

Samples were taken from patients undergoing planned orthopaedic surgery (some with and some without suspected infection). Each specimen was harvested with separate instruments. The specimens were placed into universal containers without broth according to our standard protocol and also into containers with broth. These samples were cultured and the results analysed for any difference in culture growth. A total of 72 specimens were taken in the operating theatre (36 in broth, 36 without broth). The results of culture were compared to a diagnosis of infection from clinical and histological data.

Overall there were 24 true positive samples in the study (sensitivity of 66.7%) and 32 true negative samples (specificity of 88.9%). The isolation of bacteria from the culture of samples sent in broth had a sensitivity of 77.8% and a specificity of 83.3%. Whereas, the sensitivity and specificity of musculoskeletal specimens sent without broth were 55.6% and 94.4%, respectively.

The results of the study show that there is an increase in the rate of isolation of micro-organisms from musculoskeletal tissue samples sent directly in broth culture, compared to specimens sent without broth. However, the broth samples resulted in a higher rate of false positives. This study concludes that placing musculoskeletal specimens directly in broth in the operating theatre for culture improves the rate of microbiologial diagnosis. However, a larger study with more patients would be of use to confirm this.