ABSTRACT
Objective To investigate antibiotic resistance of Klebsiella pneumoniae and Escherichia coli in old patients with lower respiratory tract infections. Methods Kirby Bauer agar diffusion method was used to evaluate the drug sensitivity in 240 strains of Klebsiella pneumoniae and Escherichia coli isolated from patients with lower respiratory tract infection. Phenotypic confirmatory test recommended by NCCLS1999 was used to detect extended spectrum beta lactamases(ESBLs). Results The resistant rates of Klebsiella pneumoniae and Escherichia coli to 14 antibiotics in old patients and in non old patients with lower respiratory tract infections were amoxicillin 93 2% vs 87 3%, piperacillin 57 1% and 42 9%, cefuroxime 51 4% and 33 3%, cefotaxime 40 1% and 17 5%, ceftazidime 13 6% and 3 2%, ceftriaxone 39 0% and 17 5%, cefoperazone 37 3% and 15 9%, cefepime 10 2% and 3 2%, amikacin 47 5% and 34 9%, ciprofloxacin 54 2% and 38 1%, imipenem 0, cefoperazone/sulbactam 0, piperacillin/tazobactam 1 1% vs 0, and cefmetazole 9 6% and 4 8% respectively. Out of 240 clinical strains of Klebsiella pneumoniae and Escherichia coli, 78(32 5%) were considered ESBLs producers by phenotypic confirmatory test. The prevalence of ESBLs in old patients was 38 4%, which was much higher than that in non old patients(15 9%). The resistant rate of ESBLs producing strains to imipinem, cefoperazone/sulbactam, piperacillin/tazobactam and cefmetazole was the lowest, being 0, 0, 2 6% and 12 8%. Conclusions The resistant rates of Klebsiella pneumoniae and Escherichia coli to most antibiotics and the prevalence of ESBLs in old patients with lower respiratory tract infection were higher than that in non old patients. Imipinem, cefoperazone/sulbactam, piperacillin/tazobactam and cefmetazole were the effective antibiotics to infections caused by ESBLs producing strains.