The Clinical And Basic Research Of Hospital-acquired Pneumonia In The Elderly Due To Achromobacter Xylosoxidans

1.Objective:(1) To research the clinical features, antibiotics-resistant phenotypes andtherapy the of Achromobacter xylosoxidans infections in the elderly patients in PLAGeneral Hospital, a retrospective analysis of hospital-acquired pneumonia (HAP)caused by Achromobacter xylosoxidans during2008-2011was performed.(2)To acquirethe Allele type and ST, the clinical strains of Achromobacter xylosoxidans isolated fromthe sputum specimens were examined by MLST.(3)Associated with theantibiotics-resistant phenotypes,the type of intergon and the genes cassettes wereanalysed by using PCR.2.Methods:(1)28cases were analyzed, including the general conditions, medicationhistory, underlying diseases, clinical features,microbiology test, and outcome,etc.(2)Logging into the PubMLST data base and analysing the housekeeping genes by usingPCR compared with the public information.(3) To analyse the distribution of the type ofthe intergon and the genes cassettes which may be associated with antibiotics-resistantphenotypes,the PCR was used.3.Results:(1)Hospital-acquired Pneumonia in the elderly due to Achromobacterxylosoxidans often occurred in patients complicated with underlying diseases. Beforeinfected with Achromobacter xylosoxidans, most of the patients had been experiencedintubation and received broad-spectrum antibiotics.Fever and the higher WBC levelaccounted for60.7%(17/28) and32.1%(9/28).However, the increase of neutrophils waspredominant(89.3%) and the increase of CRP accounted for85.7%(24/28)．In drugsensitive test,the resistant rate to amikacin and gentamicin was attained to100.0%andthe resistant rate to aztreonam was approached to90.0%．The more effective antibioticswere as followings：trimethoprim and sulfame-thoxazole (82.1%)，cefoperazone andsulbactam (83.3%)，piperacillin and tazobactam (89.3%)．The initial use of antibioticsincluded carbapenems (46.4%), quinolones (42.9%), piperacillin/β-lactamase inhibitors (21.4%) and the3rd generation cephalosporins/β-lactamase inhibitors (21.4%)．24patients (85.7%) got better，and4patients (14.3%) died in30days.(2) The total STs istwelve,including eleven news.The blaOXA-114was detected by PCR in all theAchromobacter xylosoxidans.(3)15strains presented a890bp amplicon and it wasshown that these strains contains class I intergon. Neither intII nor intIII was detected.Three different fragments were detected. A band of534bp were found in2strains andDNA sequencing shown genes cassettes aadB on the intI,which contributes to theresistance of the aminoglycoside.A band of993bp were found in1strains and DNAsequencing shown that there were two genes cassettes including dfrA17and aacA4onthe intI,which contributes to the resistance of the trimethoprim and aminoglycoside.11strains which were detected at a band of993bp shown that there were two genescassettes including aadB and aacA2on the intI,which contributes to the resistance ofaminoglycoside.A band of2220bp were analysised and the result revealed thatblaPSE-1+aac(6’)-II+aadB located in the intI.4. Conclusions:(1) The clinical features of hospital-acquired pneumonia in the elderlydue to Achromobacter xylosoxidansis nontypical. β-lactams/β-lactamase inhibitors areeffective in the treatment of elderly patients who suffered from HAP caused byAchromobacter xylosoxidans.(2)Hospital-acquired pneumonia in the elderly due toAchromobacter xylosoxidans did not show intensely correspondence either in time or inarea.The ST=N8strains show the resistance to the broad-spectrum antibiotics,especiallythe β-lactam antibiotics and the carbapenems antibiotics.The diversity of theblaOXA-114was confirmed by using PCR.（3）Compared with other organisms, the intIwas highly detected in Achromobacter xylosoxidans. However,neither int2nor int3wasconfirmed.In the varied areas,there were six different drug gene cassettes whichassociated with antibiotics-resistant phenotypes.