OBJECTIVE To survey the hospital infection of Acinetobacter baumannii in an ICU during one week's time,and study its antibiotic resistance pattern and homogeneity.METHODS The antibiotic resistance patterns of 17 A.baumannii strains were obtained by K-B method,and their homogeneity information was determined using random amplified polymorphic DNA(RAPD).RESULTS Twelve strains of A.baumannii were isolated from the ICU,among which 3 were isolated from patients,and 9 were isolated from the surface of facilities in the ICU.Eleven strains were found to be multi-antibiotic resistant,and their resistance patterns were the same with the 5 strains from patients.RAPD results showed that the 3 strains from patients and 8 strains from the environment had the same genotype.CONCLUSIONS A small outbreak of a genotype of A.baumannii infection happens in the ICU.

OBJECTIVE To find out the situation of bacteriological contamination of oxygen humidified fluid in the hyperbaric oxygen chamber in Nanfang Hospital and take appropriate measures accordingly to provide valuable reference for avoiding possibly resulting hospital infection.METHODS Before and after beginning periodically changing oxygen humidified fluid,the humidifying fluid in the oxygen humidifiers of three hyperbaric oxygen chambers in this hospital was sampled once a season.The samples were analyzed with bacteria counting and identification.RESULTS The average amount of bacteria in the samples before and after changing oxygen humidified fluid was(7.9 ? 104) CFU/ml and(2.8 ? 103) CFU/ml,respectively.Identified bacteria were conditioned pathogens,including Chryseobacterium,Acinetobacter baumannii,Escherichia coli,Pseudomonas aeruginosa,Candida albicans,etc.Among them the frequency of Chryseobacterium was the highest.The results had no correlation with the changing of seasons.CONCLUSIONS Hyperbaric oxygen chamber should be disinfected periodically,the humidified fluid should be changed every day,and the amount of bacteria in it should lower than 103 CFU/ml.

OBJECTIVE To study the characteristics of pathogens and risk factors of ventilator-associated pneumonia(VAP) in our hospital to determine the prevention and treatment strategies. METHODS Prospective observation was performed in all the ventilator-related patients in 2004. RESULTS Seventy eight events of ventilator-related pneumonia among 56 cases occurred from all the 202 ventilator-related patients,the infection incidence was 98/1000VDs.The revealed important risk factors were oldness,coma,tracheotomy,use of H-2 receptor inhibitors,and prolonged mechanical ventilation.64.8% of the pathogens were G-bacilli,among which Pseudomonas aeruginosa contributed majority accounting for 22.7%,fungi accounting for 20.5%.There was wide resistance to antibiotics in G+ pathogens,including all of the isolated Staphylococcus. CONCLUSIONS VAP is caused predominantly by G-bacteria,fungi,and multiple predisposing factors.The combined treatment is necessary for control of VAP.

Objective To study phylogenies, epidemiology and genetic environment of CTX-M type of ESBLs produced by Escherichia coli and Klebsiella pneumoniae isolated from nine hospitals in Guangzhou. Methods The phylogenies of CTX-M type of ESBLs were analyzed by PCR Genetic environment of CTX-M-15 encoding gene (bla_(CTX-M-15)) were investigated by conjugation test and plasmid analysis. The clonal relationship of strains producing CTX-M-15 was determined by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). Results A total of 361 ESBLs-producing isolates of Escherichia coli and Klebsiella pneumoniae were collected. 67.3% of ESBLs strains were detected to produce CTX-M-type ESBLs, and the commonest genotypes in Escherichia coli and Klebsiella pneumoniae were CTX-M-14 (35.4% and 28.3%), CTX-M-15(21.5% and 26.1%) EBIC-PCR products of all CTX-M-15-producing strains show 39 strains of Escherichia coli were classified into 27 genotypes while 43 strains of Klebsiella pneumoniae were divided into 30 genotypes. Furthermore, the genotypes of CTX-M-55, CTX-M-19, CTX-M-27, with ceftazidime-hydrelyzing activity, were detected in this study. The great majority of bla_(CTX-M-15) genes were found to locate on a 65 000 bp-conjugative plasmid, and there was no blaTEM-1, bla_(OXA-1), blaDSA-1 or aac (6')-Ib-cr gene coexisted on the plasmid, ISEcp1-like insertion sequences, relative to mobilization of bla_(CTX-M-15) gene, were detected in all bla_(CTX-M-15) positive strains, and the distances between the end of ISEcp1-like insertion sequences and the start cedon of bla_(CTX-M-15) were equal, with 48 base pairs. Conclusion CTX-M-14 is still the most common genotype of ESBLs in Guangzhou, but high prevalence of CTX-M-15 ESBLs hydrolyzing ceftazidime already appears in south China.