title: Osteoarticular infection caused by MDR Pseudomonas aeruginosa: the benefits of combination therapy with colistin plus β-lactams.
abstract: OBJECTIVE
  In the era of emergence of MDR Pseudomonas aeruginosa, osteoarticular infections (OIs) add more difficulties to its treatment. The role of β-lactams (BLs) is questioned and older drugs need to be reconsidered. The objective of this study was to describe our experience in the management of OIs caused by MDR P. aeruginosa and evaluate different therapeutic options.
  
  
  METHODS
  This was a retrospective analysis of a prospectively collected cohort (2004-13) of patients with OI caused by MDR P. aeruginosa. We created two groups: (i) Group A (more difficult to treat), prosthetic joint infections (PJIs) and osteoarthritis (OA) managed with device retention; and (ii) Group B (less difficult to treat), OA managed without device retention. Antibiotic treatment was administered according to clinician criteria: monotherapy/combined therapy; and BL used by intermittent bolus (IB)/continuous infusion.
  
  
  RESULTS
  Of 34 patients, 15 (44.1%) had PJI and 19 (55.9%) had OA (8 related to an orthopaedic device). Twenty-three cases (68%) were caused by XDR P. aeruginosa. The initial management included removal of an orthopaedic device in 14 cases, together with antibiotic [alone, 19 (55.9%; 4 colistin, 14 BL-IB and 1 BL continuous infusion); and in combination, 15 (44.1%; 5 BL-IB and 10 BL continuous infusion)]. The overall cure rate was 50% (39% and 63% in Groups A and B, respectively), ranging from 31.6% with monotherapy to 73.3% with combined therapy (P = 0.016), with special interest within Group A (cure rate with combined therapy 71.4%, P = 0.049). After rescue therapy, which included removal of remaining devices, the cure rate reached 85.3%.
  
  
  CONCLUSIONS
  We suggest that the BL/colistin combination is an optimized therapy for OI caused by MDR P. aeruginosa, together with an appropriate surgical treatment.
authors.affiliation: Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain albaribera@gmail.com.
authors.forename: Alba
authors.initials: A
authors.lastname: Ribera
authors.affiliation: Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Benavent
authors.affiliation: Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Lora-Tamayo
authors.affiliation: Microbiology Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain Ciber de Enfermedades Respiratorias ISCIII, Madrid, Spain.
authors.forename: Fe
authors.initials: F
authors.lastname: Tubau
authors.affiliation: Orthopaedic Surgery Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Pedrero
authors.affiliation: Orthopaedic Surgery Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Cabo
authors.affiliation: Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Ariza
authors.affiliation: Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Murillo
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D003091:Colistin / Q000494:pharmacology / Q000627:therapeutic use*; D024901:Drug Resistance, Multiple, Bacterial; D004359:Drug Therapy, Combination / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000188:drug therapy* / Q000382:microbiology; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000188:drug therapy* / Q000382:microbiology; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D012189:Retrospective Studies; D016896:Treatment Outcome; D047090:beta-Lactams / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D003091:Colistin