| Recent years, the number of nosocomial infections due to opportunistic pathogens has been raised with the increasing use of antibiotics and invasive diagnostic and treatmental measures, of which Flavobacterium was given great attention because of its high resistance to many β-lactam antibiotics such as the third generation cephalosporins, aminoglycosides and carbapenems. Although Flavobacterium-caused infections only accounted for 0.4%-0.8% of the total nosocomial infections, the mortality rate of pneumonia caused by it in neonates and children reached as high as 55%-75%. Flavobacterium has apparently become an important kind of nosocomial pathogen and been a part of subjects of surveillancing and controlling the nosocomial infections. The previous studies have shown that , besides outer membrane permeability decrease that prevented the antibiotics from entering the cells, producing beta-lactamases (bla) which can hydrolyze β-lactam　antibiotics was the main reason of Flavobacterium resistant to cephalosporins and carbapenems. Since the nosocomial infections caused by Flavobacterium only emerged recently, the study on its resistance to antibiotics was still in the beginning stage. Since 1999, there have been a few abroad reports about Flavobacterium producing extended-spectrum β-lactamases (ESBLs) and metallo- enzymes, however, the domestic studies on Flavobacterium- caused nosocomial infections were mostly case reports. In this study, 6 clinical strains of Flavobacterium isolated from nosocomial infections during 2001-2002 in Southwest Hospital were as targets of investigation. Based on the results of susceptibilities to antibiotics used clinically, the strains producing β-lactamase were examined by Kirby-Bauer test. The gene encodedβ-lactamase in the bacteria producing β-lactamases was analyzed by polymerase chain reaction (PCR), gene sequencing and homology analyzing so as to uncover the occurrence and mechanism of resistance toβ-lactam　antibiotics in Flavobacterium. The study was divided into four parts: (1) susceptibility of clinical isolates of Flavobacterium to antibiotics and rough selection of the strains producingβ-lactamases.(2) PCR product analysis of β-lactamases in the clinical isolates of Flavobacterium. (3)analyzing the sequence and analogy of the PCR products of β-lactamase genes carried in the strains of Flavobacterium. (4) analysis of risk factors in nosocomial infections due to Flavobacterium and corresponding nursing interventions.1 Methods1.1 Susceptibility of Flavobacterium to antibiotics The minimum inhibitory concentrations (MICs) of the clinical strains of Flavobacterium were determined by Kirby-Bauer disc diffusion test and the agar dilution method. 1.2 Determination of Flavobacterium produced β-lactamases and ESBLs The stains producing β-lactamases were examined by Nitrocefin disc test and ESBLs-producing isolates were roughly selected by double-disc synergy method. 1.3 Analysis of β-lactamase gene of Flavobacterium Specific primers corresponding to genetic sequences of differentβ-lactamases were designed. With the chromosome and plasmid of the clinical isolates being template,PCR were performed to determine β-lactamase gene in the strains studied.1.4 Sequencing and homological analysis of β-lactamase gene of Flavobacterium PCR products of β-lactamase gene in Flavobacterium were sequenced and their homology were compared to the known β-lactamase gene counterparts reported in Genbank. 1.5 Nursing interventions for the Flavobacterial infection Nursing interventions in controlling Flavobacterial infections were discussed according to data of the patients from whom the strains in this study were collected and the reports in public press.2 Results2.1 The susceptibility of the clinical isolates of Flavobacterium to antibiotics All the 6 clinical strains of Flavobacterium were highly resistant to β-lactam and monobactam antibiotics such as Penicillin,Ampicillin,Cefoperazone,Ceftazidime,Ceftriaxone,Cefotaxime, Aztreo...
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