Distribution and drug resistance of bacterial pathogens isolated from orthopedic wounds during 2008 and 2012

Abstract

Objective To investigate the distribution and drug resistance of bacterial pathogens isolated from orthopedic wounds. Methods Data of bacterial strains isolated from orthopedic wounds in the Third Hospital of Hebei Medical University from January 2008 to December 2012 were retrospectively analyzed. Strains were identified by using French bioMerieux Vitek32 identification system, and the drug susceptibility was tested by Kirby-Bauer method. Chi-square test for linear trend was performed to reveal the changes of distribution and drug resistance of the strains. Results A total of 2 456 bacterial strains were isolated, with 1 652 (67.26%) gram-negative bacilli, 777 (31.64%) gram-positive cocci, 26 (1.06%) fungi, and 1 (0.04%) gram-positive bacillus. The top five pathogens were Staphylococcus aureus (666 strains, 27.12%), Pseudomonas aeruginosa (606 strains, 24.67%), Acinetobacter baumannii (355 strains, 14.45%), Escherichia coli (188 strains, 7.65%) and Enterobacter cloacae (187 strains, 7.61%). The positive rate of Acinetobacter baumannii was on the rise during 2008 and 2012 (χ2=35.266, P<0.01). The rates of pan-drug resistant strains in Acinetobacter baumannii and Pseudomonas aeruginosa were 6.20% (22/355) and 0.17% (1/606), respectively. The rates of extended-spectrum β-lactamases positive strains in Escherichia coli and Klebsiella pneumoniae were 39.89% (75/188) and 29.23% (19/65), respectively. The rates of methicillin-resistant strains in Staphylococcus aureus and coagulase-negative Staphylococcus were 40.69% (271/666) and 52.38% (22/42), respectively. The rate of vancomycin-intermediate strains in Enterococci was 3.70% (2/54). The positive rate of methicillin-resistant Staphylococcus aureus was on the rise during 2008 and 2012 (χ2=18.317, P<0.01). Staphylococcus aureus were sensitive to teicoplanin, vancomycin and linezolid; Resistance rates to rifampicin and amikacin were 11.29%-33.33%; Resistance rates to penicillins and erythromycin were 76.80%-100.00%; Resistance rates to cefazolin, cefuroxime, cefoxitin, amikacin and levofloxacin were on the rise (P<0.05); And resistance rates to sulfamethoxazole (28.11%-48.35%) were on the decline in the same period (P<0.01). Resistance rates of Pseudomonas aeruginosa to imipenem, meropenem and sulfamethoxazole were on the rise (P<0.05); Resistance rates to ciprofloxacin, levofloxacin, amikacin, gentamicin and piperacillin/tazobactam were on the decline (P<0.05); Resistance rates to cefoperazone/sulbactam were the lowest (9.15%-20.51%). Resistance rates of Acinetobacter baumannii to imipenem, meropenem, levofloxacin, piperacillin/tazobactam, sulfamethoxazole were on the rise (P<0.01); Resistance rates to cefoperazone/sulbactam were the lowest (11.86%-19.70%). Escherichia coli and Enterobacter cloacae were sensitive to imipenem and meropenem, and the resistance rates to cefoperazone/sulbactam and piperacillin/tazobactam were low (0-14.29%); Resistance rates of Escherichia coli to piperacillin, cefepime, amikacin, levofloxacin, cefoperazone/sulbactam were on the decline (P<0.05); Resistance rates of Enterobacter cloacae to cefoxitin were on the rise (P<0.01), while the resistance rates to piperacillin, ceftazidime, cefoperazone, ceftriaxone, levofloxacin were on the decline (P<0.05). Conclusion During 2008 and 2012, the predominant bacterial pathogens of orthopedic wound in patients of the Third Hospital of Hebei Medical University are Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli and Enterobacter cloacae, and most strains are multiple drug resistant. Key words: Hospital, orthopedic; Wound infection; Pathogen; Drug resistance