Changes of bacterial spectrum and drug resistance in patients with posttraumatic bone infection / 中华创伤杂志

ABSTRACT

Objective To investigate the bacterial spectrum and drug resistance of bone infection after multiple hospitalizations.Methods A retrospective case series study was conducted on 95 patients with bone infection due to injuries admitted in the General Hospital of Shenyang Military Area from January 2009 to December 2016.There were 76 males and 34 females,with an average age of 47 years (range,17-94 years).Bacterial culture and drug sensitivity tests were performed in 246 specimens of the infection secretions and infected tissues.The bacterial species and drug resistance data of all the specimens were statistically analyzed.The numbers and ratios of Gram-positive bacteria and Gram negative bacteria were counted according to the changes of hospitalization frequency,and the changes of drug resistance of Staphylococcus aureus after repeated hospitalizations were also recorded.Results A total of 110 pathogenic bacteria were isolated,and mixed infection was found in 19％ of the bacteria.There were 61 Gram-positive bacteria (55.5％),including 35 Staphylococcus aureus [seven methicillin-resistant staphylococcus (MRSA) strains],accounting for 57％ of Gram-positive strains.Other Gram positive bacteria were mainly Enterococcus faecalis and Staphylococcus epidermidis.There were 48 Gram-negative bacteria (43.6％),including 12 Pseudomonas aeruginosa strains,accounting for 25％ of Gram-negative strains,nine Klebsiella pneumoniae strains,accounting for 19％ of the Gramnegative strains.Staphylococcus aureus had a resistance rate to penicillin of 82％,and the major Gram positive bacteria (Staphylococcus aureus,Enterococcus faecalis,Staphylococcus epidermidis) were all highly sensitive to vancomycin and linezolid.The major Gram-negative bacteria (Pseudomonas aeruginosa,Klebsiella pneumoniae,Escherichia coli,Acinetobacter baumannii) were highly resistant to the second generation of cephalosporins and were sensitive to carbapenem antibiotics.In 95 bone infection patients,the ratio of Gram positive bacteria to Gram negative bacteria increased from 0.98 at the first admission to 3 after repeated hospitalizations,and the ratio change was statistically significant (P ＜0.05).After multiple hospitalizations,the drug resistance of Staphylococcus aureus to gentamicin,ciprofloxacin,levofloxacin,and tetracycline increased gradually.The resistance rate to penicillin was even up to 100％.Conclusions The mixed infection of bone infection is common,among which Staphylococcus aureus and Staphylococcus epidermidis are the main Gram-positive pathogenic bacteria,Pseudomonas aeruginosa and Klebsiella pneumoniae are the main Gram negative pathogenic bacteria.The proportion of Gram-positive bacteria infection increased after multiple hospitalizations and became the major pathogenic bacteria.Penicillin should be avoided in the treatment of Staphylococcus aureus infection in multiple hospitalizations,and gentamicin and ciprofloxacin should be used with caution.Vancomycin or linezolid which is more sensitive is a better option.