[Analysis of the drug-resistance of Pseudomonas aeruginosa and the use of antibiotics in burn wards].

OBJECTIVE: To study changes in the drug-resistance of Pseudomonas aeruginosa (PA) and the use of antibiotics in burn wards so as to optimize the use of antibiotic in the future.

METHODS: Bacteria were isolated from specimens of blood, venous catheter, stool, sputum, urine, wound tissue from 5717 patients hospitalized in our burn wards within the duration of January 2005 to December 2009. The number of specimens examined and positive rates of bacteria were calculated. Changes in constituent ratio of cocci and bacilli, spectrum of bacteria, the drug-resistance rate of PA, and the usage of antibiotics were analyzed. The number of specimens examined, constituent ratio of cocci and bacilli, drug-resistance rate were processed with chi-square test. Bivariate correlation analysis was performed between the usage of antibiotics and the drug-resistance rate.

RESULTS: (1) The number of specimens examined showed no statistical difference during the five years (with rates from 73.2% to 76.1%, χ(2) = 5.583, P > 0.05), while constituent ratio of cocci and bacilli showed statistical difference (with ratios from 105:134 to 169:126, χ(2) = 14.806, P < 0.01). The positive rates of bacteria were increasing in the five years. (2) One thousand six hundred and seventy-five strains were identified during the five years from different kinds of specimens, with 29 from blood, 39 from venous catheter, 3 from stool, 157 from sputum, 13 from urine, and 1434 from wound tissue. Among them, Staphylococcus aureus accounted for 28% to 42%, PA accounted for 10% to 25%, Acinetobacter baumannii accounted for 10% to 19%, and they were the predominant strains. (3) The difference among drug-resistance rates of PA to each kind of 12 antibiotics during the five years were statistically significant (with χ(2) values from 47.911 to 308.095, P values all below 0.01). The drug-resistance rates of PA to some antibiotics showed downward trend in the former four years, including amikacin, ceftazidime, and imipenem/cilastatin, but it rebounded in the fifth year. (4) There was descending trend in usage of cefoperazone/sulbactam and levofloxacin, but vancomycin was always used widely. (5) Drug-resistance rates of PA to 7 antibiotics, including amikacin, imipenem/cilastatin, and ciprofloxacin, etc., were positively correlated with usage of various antibiotics (with r values from 0.879 to 0.978, P < 0.05 or P < 0.01).

CONCLUSIONS: In our burn wards, drug-resistant PA was prevalent. Disinfection and isolation measures, appropriate use of antibiotics, etc. can reduce PA infection.