Objective To investigate the genetic polymorphism of methicillin resistant Staphylococcus aureus ( MRSA) isolated from hospital acquired pneumonia. Methods Seventy-four hospitalized patients were diagnosed as noscomial MRSA pneumonia from January 2007 to January 2008 in Xinhua Hospital, Shanghai Jiaotong Univesity. The genes of MRSA were amplified by random amplified polymorphic DNA typing ( RAPD) assay in 82 clinical isolates from these patients. Results Two to 15 amplified DNA fragments were observed in agarose gel and they were classified into 11 genotypes. Genotypes Ⅲ, Ⅵ and Ⅶ ( 32. 56% , 30. 23% and 13. 95% , respectively) were mainly isolated from the ICU. Both independent genotypes and overlapping genotpyes with those from ICU were identified in isolates from the departments of geriatrics, emergency and respiratory medicine. Outbreak or cluster cases ( 48. 65% ) were found in 36 of the 74 patients while all outbreak cases occurred in the ICU. Conclusions Noscomial MRSA pneumonia is easy to disseminate and small-scale outbreak may occur especially in ICU. RAPD is valuable for identification and prevention of the spread of MRSA in hospital.
Objective To investigate the mutations of quinolone resistance determinational region ( QRDR) in fluoroquinolon-resistant Pseudomonas aeruginosa strains isolated from patients with nosocomial pneumonia. Methods Eight-four Pseudomonas aeruginosa strains isolated from patients with nosocomial pneumonia in Xinhua Hospital during January 2006 to December 2007, from whom fluoroquinolon-resistant resisitant ( case) and fluoroquinolon-susceptible ( control ) Pseudomona aeruginosa were identified. The mutation of QRDR was tested by restriction fragment length polymorphism ( RFLP) and gene sequencing.The relationship between QRDR mutations and clinical prescription was analyzed. Results Mutation in QRDR was found in 42 isolates among the 50 fluoroquinlon-resisitant isolates( 84. 0% ) , while no mutation was found in fluoroquinlon-susceptible isolates. The mutation in GyrB Ser464 was found in 34 isolates ( 68. 0% ) . There was statistical difference in the usage of β-lactams between the GyrB-Ser464-mutated group and the non-GyrB-Ser464-mutated group( OR = 11. 3, P = 0. 003 and OR = 3. 5, P = 0. 023) , also in the time of fluoroquinolon usage before isolated ( P = 0. 038) . Conclusions The mutation of QRDR is contributing to fluoroquindor-resisitance of Pseudomona aeruginosa, most of which lies in GyrB Ser464.Abuse of β-lactams and fluoroquinolon may be the risk factors of mutation in GyrB Ser464.
Objective To analyze the current drug resistance and risk factors of hospital acquired pneumonia( HAP) due to extended spectrumβ-lactamase ( ESBLs) producing Escherichia coli and Klebsiella pneumoniae, and to estimate the prevalence trend of ESBLs producing strains. Methods FromApril 2007 to January 2008, 140 patients of Xinhua Hospital with HAP due to E. coli and K. pnermoniae were enrolled.Among them, 88 patients were with ESBLs producing strains and 52 patients were with non-ESBLs producing strains. Risk factors were analyzed by comparing between these patients. The rate of drug resistance was determined by antibiotic sensitive test. Fifty-three ESBLs producing strains were genotyped by random amplified polymorphic DNA ( RAPD) . Results The rate of drug resistance of ESBLs producing strains washigher than that of non-ESBLs producing strains. ICU stay, use of third- and forth-generation cehpalosporin were found to be the independent risk factors by multivariate analysis with logistic regression. By RAPD, 37 ESBLs producing E. coli strains were divided into 27 types and 16 ESBLs producing K. pneumoniae strains were divided into 13 types. Conclusions ICU stay, use of third-generation and forth-generation cehpalosporin remain as major risk factors in the HAP due to ESBLs producing E. coli and K. pneumoniae.RAPD is an economic, quick and credible method for epidemic analysis