Characterization of Imipenem Unsusceptible Pseudomonas Aeruginosa Isolates from Inpatients without Carbapenem Treatment

Objective To identify the risk factors for imipenem resistance development and transmission of clinical Pseudomonas aeruginosa isolates.Methods Thirty-seven imipenem unsusceptible Pseudomonas aeruginosa isolates collected from patients in absence of carbapenem treatment were characterized by antimicrobial susceptibility test,pulsed field gel electrophoresis(PFGE)and carbapenem resistant mechanism analysis.Results Before the collection of imipenem unsusceptible Pseudomonas aeruginosa isolates,the average time of patients treated with more than one antimicrobial(20.0±9.5 days,n=16)was significantly longer than those treated with only one antimicrobial(12.6±4.4 days,n=21;t-test,Welch,t=-2.9004,P<0.01).And 32 isolates showed resistance to more than 3 classes of antimicrobials.Six PFGE clusters were identified and 26 isolates were grouped into one dominant cluster(C2).An ISpa1328 sequence insertion in oprD was detected in 33 isolates and the function of efflux was observed in all 37 isolates in the presence of a wide spectrum efflux inhibitor.Conclusions Our data demonstrated that exposure to non-carbapenem drug classes,especially fluoroquinolones andβ-lactams,may be important risk factors for the spread of carbapenem resistant Pseudomonas aeruginosa.

Detection of the Relationship between Imipenem Susceptible and Non-Susceptible Clinical Isolates of Acinetobacter Baumannii by Repetitive Element PCR-Mediated DNA Fingerprinting in an Egyptian Hospital

In this work, the authors aimed to detect the clonal relatedness of the isolated imipenem-susceptible and non-susceptible Acenitobacter baumanii. This study was conducted from September 2008 through August 2009 in Aboelreech-Elmounira paediatric-Cairo University-teaching hospital in Egypt. All the isolated acenitobacter species were identified by standard laboratory procedures. The clonal relationship of the A. baumanii （the most common detected clinical type） was studied by biotyping and AST and then confirmed using rep-PCR with primers aimed at repetitive extragenic palindromic sequences and enterobacterial repetitive intergenic consensus sequences. A total of 100 A. baumanii isolates out of 104 acenitobacter species were recovered from different clinical samples. Sixty two percent of the isolates were resistant to imipenem. The resulting rep-PCR patterns oftheA, baumanii strains revealed 8 clones, 3 clones found in the imipenem resistant group, and 5 clones in imipenem sensitive group with statistically significant clonal distribution in both groups （P-value 0.00）. Clonality was proved in imipenem resistant group with an alarming predominance of clone 1 representing 80.6% of IMP-R isolates. In accordance the prevalence of resistant acenitobacter strains seems to be correlated with inappropriate antibiotic use. These results call for strict compliance of coordinated strategy of infection control measures and judicious use of antimicrobials which is likely to effectively deal with this serious public health issue.