Investigation of extended-spectrum beta-lactamase in Klebsiellae pneumoniae and Escherichia coli from China.

Extended-spectrum beta-lactamases (ESBLs) are an increasing cause of resistance to third-generation cephalosporins in Enterobacteriaceae. However, they have not been well studied in China. We investigated the prevalence, resistance, and probable gene type of ESBLs using MICs testing and polymerase chain reaction in 559 Klebsiellae pneumoniae and 427 Escherichia coli isolates collected from patients in Huashan Hospital from 1 January to 31 December 1999. The incidence of ESBL-producing strains was 51% among Klebsiellae pneumoniae (285/559) and 23.6% among Escherichia coli (101/427), most of which were collected from patients in intensive care unit and neurosurgical ward. PFGE showed that some epidemic ESBL-producing strains were present in the ICU, especially among ESBL-producing Klebsiellae pneumoniae. The major source of ESBL-producing Klebsiellae pneumoniae and Escherichia coli was sputum specimen (63.5%) and urine (64.3%), respectively. These strains were resistant to most beta-lactams (including the third-generation cephalosporins and monobactams) and non-beta-lactams (such as fluoroquinolones, aminoglycosides, tetracycline, and chloramphenicol), all or most ESBL producers were susceptible to imipenem, cefmetazole and beta-lactam/clavulanic acid. TEM was the main type of beta-lactamases and the CTX-M type of ESBLs was common in these isolates. Some ESBL-producing Escherichia coli and most ESBL-producing Klebsiellae pneumoniae produced more than one type of beta-lactamase. These data confirm that ESBL producers are common among hospital strains of Escherichia coli and Klebsiellae pneumoniae in China. It is important to monitor such strains closely and prevent their spread.