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Pathogen identification in 84 Patients with post-traumatic osteomyelitis after limb fractures.

BACKGROUND
Chronic osteomyelitis is a serious complication of orthopedic trauma. Residual bacteria after incomplete debridement and/or bacterial colonization, bacterial biofilm formation, and generation of antibiotic-resistant bacterial strains in the microtubule system of compact bones due to irrational use of antibiotics often make the condition more prolonged, recurrent, and refractory. The passive immunotherapy targeting the protein components of bacteria has become an area of intense research interest, for which identifying the bacterial isolates in different areas at different time points remains a key step. Few multicenter randomized controlled trials have investigated the epidemiological data of pathogens in different areas, and there is a lack of timely and dynamic data that can inform clinical treatment.


METHODS
A total of 5,268 patients with limb fractures were treated in our center from January 1, 2012, to December 31, 2015, among whom 108 were diagnosed with post-traumatic osteomyelitis (PTO) based on clinical manifestations, imaging findings, and pathology. Bacteria cultures showed positive results in 84 patients. The clinical manifestations (including the infection site) were analyzed. The distribution and drug resistance of pathogens were analyzed and summarized based on the M-100-S22 protocol [Clinical and Laboratory Standards Institute® (CLSI) 2012, USA].


RESULTS
The incidence of PTO in limbs was 2.1% (n=108), and the bacterial cultures were positive in 84 patients (84/108, 77.8%). The infection sites included the tibia and fibula (n=40, 47.6%), femur (n=20, 23.8%), ulna and radium (n=11, 13.1%), humerus (n=5, 6%), patella (n=5, 6%), and calcaneus (n=3, 3.6%). In total, 104 of the following bacterial strains were identified: 56 strains of gram-positive bacteria (53.9%), among which Staphylococcus aureus (n=39, 37.5%) and Staphylococcus epidermis (n=6, 5.8%) were the most dominant bacteria, with both being sensitive to ampicillin, quinupristin, linazolamide, tigarycline, nitrofurantoin, and vancomycin; 48 strains of gram-negative bacteria (46.1%), among which Escherichia coli (n=16, 15.4%) and Enterobacter cloacae (n=11, 10.6%) were the most common bacteria, with both being sensitive to thiomycin; mixed infections were detected in 18 cases (21.4%).


CONCLUSIONS
The incidence of PTO in the Zunyi area is similar to the national level. The most common site of infection is the lower extremity. Bacterial infections (mainly infection caused by a single bacterial type) were observed in 77.8% of the cases. Staphylococcus aureus is the most common pathogenic bacteria, followed by Escherichia coli and Enterobacter cloacae. The antibiotic-resistant bacteria have characteristic distributions in different regions.