Abstract
Aim
This study quantified changes in the microbiology of osteomyelitis in a single specialist centre within the UK. The rate of infection with multi-drug-resistant (MDR) bacteria was measured over a ten year period in 388 patients.
Method
Patients with confirmed osteomyelitis who received curative surgery from 2013–2017 were included (n=222). Microbiology was compared to patients from a cohort between 2001–2004, using the same diagnostic criteria (n=166).1 The proportion of MDR bacterial pathogens2 from deep tissue culture in these cohorts were compared. Pathogens were analysed according to aetiology and the presence of metal-work.
Results
Both cohorts had similar baseline characteristics. A median of five tissue samples were submitted for each patient. The proportions of specific pathogens remained unchanged between the two cohorts, with the exception of a decrease in the proportion of coagulase-negative Staphylococcus (CoNS) (12.7% vs 5.3%, p<0.05). Although the overall proportion of Staphylococcus aureus remained similar, the rate of MRSA infection decreased in the 2013–2017 cohort when compared to the 2001–2004 cohort (30.7% vs. 10.5% of Staphylococcus aureus, p<0.05). However, the proportion of MDR Enterococcus, Pseudomonas and Enterobacteriaceae did not differ between the two cohorts (37.3% vs. 35.7%).
There were no differences in microbiology of the 2013–2017 cohort that related to presence of metal-work or aetiology of infection. A higher proportion of haematogenous osteomyelitis were culture-negative compared to other aetiologies (37.1% versus 20.3%).
Conclusions
In this UK centre over the past 10 years, rates of MRSA osteomyelitis have fallen by two thirds, which is in line with the reducing rate of MRSA bacteraemia nationally. However, the proportion of other MDR bacteria remained unchanged. A decrease in the proportion of CoNS may reflect improved sampling technique and culture. Furthermore, this study demonstrated that classification by aetiology or the presence of metal-work does not predict the pathogen in adults with chronic osteomyelitis.
