Distribution and antibiotic resistance analysis of extended spectrum β-lactamases in older patients with hospital-acquired pulmonary infection

Objective To investigate the distribution and antibiotic resistance of the extended spectrum β-lactamases(ESBLs) in older patients with hospital-acquired pulmonary infection.Methods A total of 978 patients who were treated in Yangpu Geriatric Hospital and Shidong Hospital during Oct.2006 to Oct.2007 were studied,and 78 patients meeting the hospital acquired pneumonia(HAP) criterion were retrospectively analyzed.Results The incidence of HAP was 7.98%(78/978).The qualified sputum specimen bacterial positive rate was 61.9%(164/265).There were 39 strains of ESBLs bacteria,accounting for 31.7%(39/123)of the gram-negative bacteria.ESBLs-producing strains were positive in 51.5%(17/33) of Escherichia coli,45.2%(14/31) of Klebsiella pneumoniae,and 17.6%(3/17) of Proteus mirabilis isolates.ESBLs-producing Escherichia coli strains had a 90% resistant rates to Ampicillin Sodium,Piperacillin Ciprofloxacin,Cefuroxime,Cefotaxime,and Cefazolin,and had a resistance rate of 54.7% to Aztreonam,but had a lower resistance rate to Cefoxitin,Cefoperazone/Sulbactam,Piperacillin Sodium and Tazobactam Sodium,Cefoxitine,and Ceftazidime.ESBLs-producing Klebsiella pneumoniae had a 90% resistance rate to Ampicillin Sodium,Cefuroxime,and Cefazolin,a 80% resistance rate to Cefotaxine and Piperacillin,a resistance rate of 71.7% to Aztreonam,and lower resistance rates to Piperacillin/Tazobactam and Cefoxitin.Conclusions The ESBLs producing stains of Escherichia coli and Klebsiella pneumoniae are high in our cohort,and most of them are multiple drugs resistant.ESBLs-producing strains should be suspected when the isolated Escherichia coli and Klebsiella pneumoniae are resistant to third generation cephalosporin,such as Cefotaxime and Ceftriaxone.ESBLs-producing strains should also be suspected when Gram negative strains are sensitive to third generation cephalosporin,but failure in treatment occurs.(Shanghai Med J,2009,32: 876-880)