Cure of multidrug-resistant Acinetobacter baumannii prosthetic material-related orthopaedic infections with intravenous colistin

Abstract number: 1134_04_153

Kasiakou S., Fragoulis K., Tzagarakis G., Mistidis P., Kapaskelis A., Falagas M.

Background:  

Multidrug-resistant (MDR) Gram-negative bacteria, including Pseudomonas and Acinetobacter spp., are frequent causes of osteomyelitis, and septic arthritis now-a-days. For such infections, colistin has not been considered as an alternative to the conventional therapeutic intervention, mainly due to its reported in the old literature inadequate penetration in these tissues.

Methods:  

We describe two cases of MDR Acinetobacter baumannii prosthetic material-related orthopaedic infections which where successfully treated with intravenous colistin.

Results:  

A 53-year-old male was admitted with complicated left proximal femur fracture. He underwent surgical debridement of the necrotic tissues and external fixation of the femur. However, during the ensuing days his clinical condition worsened and he became febrile. A specimen culture obtained during consecutive surgical debridement grew an Acinetobacter baumannii strain. This strain exhibited sensitivity only to colistin (MIC 0.5 mg/l) and intermediate sensitivity to gentamicin, tobramycin, and meropenem. The patient received a bolus intravenous injection of colistin 1 million IU followed by 6 million IU per day continuous infusion for 36 days. His clinical condition gradually improved. The second case was a 37-year-old male who was admitted because of fractures of both left tibial condyles. He underwent surgical treatment, which consisted of an open reduction and internal fixation. However, he became febrile 7 days after his discharge and 5 days later he was readmitted to our hospital. Physical examination showed erythema and tenderness at the region of the left knee. The patient underwent surgical debridement of the affected area. A specimen obtained from the surgical site grew an Acinetobacter baumanii strain and a Staphylococcus lugdunensis strain. The Acinetobacter baumanii strain exhibited sensitivity to colistin and gentamicin and intermediate sensitivity to meropenem and tobramycin. Subsequently, the patient was given intravenous treatment with colistin 2 million IU q8h for 22 days, and vancomycin 1gr q12h for 13 days. The patient became afebrile and was discharged after 29 days of hospitalization. No serious colistin associated toxicity developed and no recurrence of the infection occurred on follow up in both patients.

Conclusion:  

Colistin may consider as a valuable therapeutic option in cases of prosthetic material-related orthopaedic infections due to MDR Acinetobacter baumannii strains.