P0541 Paper Poster Session Management of bone and joint infections

Emergence of rifampin-resistant Staphylococcus spp. in implant-associated infections

Anca Negru1, Raluca Mihailescu2, Remulus Catana*3, Daniela Munteanu4, Olga Dorobat5, Alexandru Rafila6, Emilia Capraru2, Mariana Radut2, Vlad Predescu2, Marius Niculescu7, Rodica Marinescu8, Olivera Lupescu9, Adrian Streinu-Cercel3, Victoria Arama10, Daniela Talapan6

1National Institute for Infectious Diseases "Prof. Dr. Matei Bals", Adults 3, ,

2National Institute for Infectious Diseases “prof. Dr. Matei Balş”, Bucharest, Romania

3Carol Davila University of Medicine and Pharmacy, National Institute for Infectious Diseases “prof. Dr. Matei Balş”, Bucharest, Romania

4National Institute for Infectious Diseases “prof. Dr. Matei Balş”, Bucharest, Bangladesh

5National Institute for Infectious Diseases "Prof. Dr. Matei Balș", Bucharest, Romania

6Carol Davila University of Medicine and Pharmacy, National Institute for Infectious Diseases "Prof. Dr. Matei Balș", Bucharest, Romania

7Clinical Hospital , Bucharest, Romania

8Carol Davila University of Medicine and Pharmacy, Clinical Hospital Colentina, Clinical Hospital Colentina, Bucharest, Romania

9Carol Davila University of Medicine and Pharmacy, Emergency Clinical Hospital, Bucharest, Romania

10Prof. Dr. Matei Bals Institute , Bucharest, Romania

Background:Implant-associated infections (IAI) are correlated with high morbidity and their management remains a challenge, especially when microorganisms are resistant to antibiotics with good anti-biofilm activity. Staphylococcal IAI, the most prevalent ones, require a rifampin-including regimen, besides an adequate surgical strategy. The aim of this study was to evaluate the prevalence of rifampin-resistant staphylococci in infections occurring on medical devices.

Material/methods:A prospective 3-year study conducted in the National Institute of Infectious Diseases Prof. Dr. Matei Balș, Bucharest included the sonicated implants, which were sent from regional centers. No antibiotics were administered at least 14 days prior to the explantation surgery. Sonication at 40 kHz was performed on BactoSonic® ultrasonic bath (Bandelin, Germany). The sonicate fluid was cultured on aerob and anaerob media and incubated for 7 and 14 days, respectively. Bacteria indentification and antibiotic susceptibility tests were performed using by Vitek®2 Compact automated system (Healthcare, BioMérieux, USA) according to EUCAST breakpoints. Equivocal susceptibility results were retested with E-tests (BioMérieux, Marcy-l'Étoile, France). Results:Among the 102 sonicated devices, 51 staphylococci strains were isolated from 40 patients: 26 S. aureus and 25 coagulase-negative staphylococci (CoNS): 17 S. epidermidis, 2 S. haemolyticus, 3 S. hominis, 2 S. capitis, and 1 S. simulans. These microorganisms were involved in either monobacterial (n=21) or polybacterial (n=19) infections. There were 75 orthopaedic implants, 10 breast implants and 17 other devices. There were 30 methicillin-resistant strains, among which 14 were S. aureus strains. Rifampin resistance was found in 13 (25.5%) staphylococci of which 6 were S. aureus strains.

Conclusions:Staphylococcus spp are the most frequent bacteria involved in implant-associated infections. The problematic part of antibiotic therapy approach is raised by the emergence of rifampin- resistant staphylococci, as rifampin has an excellent activity against staphylococcal biofilm. A prevalence of 25% of staphylococcal strains resistant to rifampin narrows dramatically the therapeutical possibilities for implant-associated infections. Judicious use of antibiotics together with optimal surgical interventions are needed to avoid increasing antibiotic resistance.