BACKGROUND: Small colony variants of Staphylococcus aureus tend to persist despite antimicrobial therapy, especially when involved in implant-associated infections. METHODS: We analyzed 5 cases of hip prosthesis-associated infections due to small colony variants, including their course prior to identification of the pathogen. Biopsy investigations included microbiological examination and, in 1 case, transmission electron microscopy to detect intracellular bacteria in nonprofessional phagocytes. A treatment concept was elaborated on the basis of a published algorithm and patients were managed accordingly. RESULTS: The patients' mean age was 62.2 years. All patients experienced treatment failures prior to isolation of small colony variants, despite as many as 3 surgical revisions and up to 22 months of antibiotics. Transmission electron microscopy performed on biopsy specimens from periprosthetic tissue revealed intracellular cocci in fibroblasts. All prostheses were removed without implanting a spacer, and antimicrobial agents were administered for 5.5-7 weeks. Reimplantation of the prosthesis was performed for 4 patients. Follow-ups were uneventful in all 5 cases. CONCLUSIONS: In the case of a poor response to adequate antimicrobial and surgical treatment in implant-associated staphylococcal infections, small colony variants should be considered and actively sought. In our case series, a 2-stage exchange without implantation of a spacer combined with antimicrobial therapy for an implant-free interval of 6-8 weeks was associated with successful outcome, with a mean follow-up of 24 months.
BACKGROUND: Small colony variants of Staphylococcus aureus tend to persist despite antimicrobial therapy, especially when involved in implant-associated infections. METHODS: We analyzed 5 cases of hip prosthesis-associated infections due to small colony variants, including their course prior to identification of the pathogen. Biopsy investigations included microbiological examination and, in 1 case, transmission electron microscopy to detect intracellular bacteria in nonprofessional phagocytes. A treatment concept was elaborated on the basis of a published algorithm and patients were managed accordingly. RESULTS: The patients' mean age was 62.2 years. All patients experienced treatment failures prior to isolation of small colony variants, despite as many as 3 surgical revisions and up to 22 months of antibiotics. Transmission electron microscopy performed on biopsy specimens from periprosthetic tissue revealed intracellular cocci in fibroblasts. All prostheses were removed without implanting a spacer, and antimicrobial agents were administered for 5.5-7 weeks. Reimplantation of the prosthesis was performed for 4 patients. Follow-ups were uneventful in all 5 cases. CONCLUSIONS: In the case of a poor response to adequate antimicrobial and surgical treatment in implant-associated staphylococcal infections, small colony variants should be considered and actively sought. In our case series, a 2-stage exchange without implantation of a spacer combined with antimicrobial therapy for an implant-free interval of 6-8 weeks was associated with successful outcome, with a mean follow-up of 24 months.
Authors: Parham Sendi; Reno Frei; Thomas B Maurer; Andrej Trampuz; Werner Zimmerli; Peter Graber Journal: J Clin Microbiol Date: 2010-03-24 Impact factor: 5.948
Authors: Aldona L Baltch; William J Ritz; Lawrence H Bopp; Phyllis Michelsen; Raymond P Smith Journal: Antimicrob Agents Chemother Date: 2008-03-10 Impact factor: 5.191
Authors: Hoang Anh Nguyen; Olivier Denis; Anne Vergison; Anne Theunis; Paul M Tulkens; Marc J Struelens; Françoise Van Bambeke Journal: Antimicrob Agents Chemother Date: 2009-02-02 Impact factor: 5.191