AUDIT OF ANTIBIOTIC RESISTANCE IN INFECTED HIP ARTHROPLASTY

Abstract

Introduction: In patients presenting with an infected hip arthroplasty first-line antibiotics at our institution are Flucloxacillin and Fucidic Acid. It was observed that many patients needed their antibiotic regime changed once sensitivities became known. This was because of resistance to the first-line antimicrobial agents. This raised the question ‘How frequent is Flucloxacillin and Fucidic acid resistance in prosthetic hip infection and is there a more appropriate first-line antibiotic?’

Method: A computerised search of the Belfast Orthopaedic Information System (BOIS) identified all cases of infected hip arthroplasty from October 2001 to April 2005. All microbiology results of these patients were obtained and analysed to determine the infecting organism, sensitivity and resistance to Flucloxacillin, Fucidic acid and Teicoplanin.

Results: BOIS identified forty cases of infected hip arthroplasty, 35 primary arthroplasties and 5 revision arthroplasties. Of the 40 patients 36 had positive cultures, 3 had no growth and there was missing data on one patient. Flucloxacillin sensitivity occurred in 25% of patients with 58% resistance. With regard to Fucidic Acid sensitivity was 47 % with 44% resistance. There were no cases of Teicoplanin resistance. Teicoplanin sensitivity occurred in 78% of patients and with analysis by organism susceptibility sensitivity would measure 92% (8% were not tested against Teicoplanin).

Discussion: Flucloxacillin resistance is greater than sensitivity in infected hip arthroplasty in this study group. Fucidic Acid sensitivity and resistance are roughly equal. There are no cases of Teicoplanin resistance in our study population and with analysis with respect to the causative organism Teicoplanin sensitivity reaches 92%. It could be suggested therefore that the first-line agents of Flucloxacillin and Fucidic acid are inappropriate and that Teicoplanin may be a better choice.