title: Antibiotic susceptibility among Staphylococcus epidermidis isolated from prosthetic joint infections, with focus on doxycycline.
abstract: In recent years, coagulase-negative staphylococci such as Staphylococcus epidermidis have gained importance as nosocomial pathogens, especially in immunocompromised patients and prosthetic joint infections (PJIs). These infections are often long lasting and difficult to treat due to the production of bacterial biofilm and the transformation of the bacteria into a stationary growth phase. Rifampicin is able to penetrate the biofilm, but to reduce the risk of development of rifampicin resistance it should be used in combination with an additional antibiotic. In this study we used Etest to investigate the antimicrobial susceptibility of 134 clinical isolates of S. epidermidis obtained from PJIs to six oral antibiotics: doxycycline, rifampicin, linezolid, fusidic acid, clindamycin, and ciprofloxacin. We also performed synergy testing on doxycycline in combination with each of the remaining antibiotics. Ninety-three (69%) of the 134 isolates were susceptible to doxycycline, 94/134 (70%) to rifampicin, 56/134 (42%) to clindamycin, 25/134 (19%) to ciprofloxacin, 81/134 (60%) to fusidic acid, and 100% to linezolid. Thirty-two (80%) of the 40 isolates not fully susceptible to rifampicin were susceptible to doxycycline. Doxycycline in combination with each of the other investigated antibiotics exerted an additive effect on nearly half of the isolates, with the exception of clindamycin, which displayed an even higher percentage of additive effect (69%). To conclude, as the majority of the S. epidermidis isolates were susceptible to doxycycline, this antimicrobial agent may provide a potential alternative for combination therapy together with rifampicin.
authors.affiliation: Department of Laboratory Medicine, Clinical Microbiology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors.forename: Tarza
authors.initials: T
authors.lastname: Hamad
authors.affiliation: Department of Laboratory Medicine, Clinical Microbiology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Hellmark
authors.affiliation: Department of Infectious Diseases, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Åsa
authors.initials: Å
authors.lastname: Nilsdotter-Augustinsson
authors.affiliation: Department of Laboratory Medicine, Clinical Microbiology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Söderquist
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002939:Ciprofloxacin / Q000494:pharmacology / Q000627:therapeutic use; D002981:Clindamycin / Q000494:pharmacology / Q000627:therapeutic use; D003428:Cross Infection; D004318:Doxycycline / Q000494:pharmacology* / Q000627:therapeutic use; D024901:Drug Resistance, Multiple, Bacterial; D005672:Fusidic Acid / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007595:Joint Prosthesis / Q000382:microbiology*; D000069349:Linezolid / Q000494:pharmacology / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D016459:Prosthesis-Related Infections / Q000188:drug therapy / Q000382:microbiology*; D012293:Rifampin / Q000494:pharmacology / Q000627:therapeutic use; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013212:Staphylococcus epidermidis / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D002981:Clindamycin; D005672:Fusidic Acid; D002939:Ciprofloxacin; D000069349:Linezolid; D004318:Doxycycline; D012293:Rifampin
keywords: Etest; Implant infection; doxycycline; prosthetic joint infection; synergy testing