Determination of extended spectrum beta-lactamases, metallo-beta-lactamases and AmpC-beta-lactamases among carbapenem resistant Pseudomonas aeruginosa isolated from burn patients

Background: Pseudomonas aeruginosa is an important cause of morbidity and mortality in patients with burns. Method: A total of 214 nonduplicated burn wound isolates of P. aeruginosa were recovered from burn patients. Identification of carbapenem resistant isolates and their antimicrobial susceptibility pattern was carried out using the phenotypic methods. The presence of genes encoding extended spectrum beta-lactamases (ESBLs) and metallo-beta-lactamases (MBLs) enzymes were determined by PCR. The genetic relationships between carbapenem resistant isolates were determined by Random Amplified Polymorphic DNA (RAPD)-PCR. Results: Of 214 investigated P. aeruginosa isolates, 100 (46.7) were carbapenem resistant. All carbapenem resistant P. aeruginosa were resistant to imipenem, meropenem, ertapenem, carbenicillin, aztreonam, gentamicin and ciprofloxacin but susceptible to polymyxin B. Among 100 carbapenem resistant P. aeruginosa isolates, 3, 65 and 52 were identified as ESBLs, carbapenemase and AmpC overproduction positive isolates respectively. The most prevalent ESBLs and MBLs genes included bla(OXA-10) (97), bla(TEM) (61), bla(VIM) (55), bla(PER) (13), bla(IMP) (3) and bla(AIM) (1). RAPD analysis yielded 13 distinct profiles among 92 isolates. A dominant RAPD type was designated as A that consisting of 80 isolates. Conclusion: This is the first report of Adelaide IMipenmase (AIM) MBLs producing P. aeruginosa from Iran and also of the high prevalence of AmpC overproduction isolates. According to the results of current study, P. aeruginosa isolates producing OXA-10, TEM, VIM, PER and IMP beta-lactamases are frequent and the population structures of these isolates are highly similar. (C) 2014 Elsevier Ltd and ISBI. All rights reserved

Detection of AmpC-beta-lactamases producing isolates among carbapenem resistant P. aeruginosa isolated from burn patient

BACKGROUND AND OBJECTIVES: Pseudomonas aeruginosa is responsible for devastating nosocomial infections among severely burn patients. Class C of cephalosporinase (AmpC-beta-lactamases) is important cause of multiple beta-lactam resistance in P. aeruginosa. The aim of this study was to detect the AmpC-beta-lactamases producing isolates among carbapenem resistant P. aeruginosa isolated from burn patient. MATERIAL AND METHODS: a total of 100 isolates of carbapenem resistant P. aeruginosa isolates from different burn patients were investigated. Three phenotypic methods were selected for identification of the AmpC-beta-lactamases producing isolates. RESULTS: Fifty four isolates were AmpC producer as detected by AmpC disk test. Seventeen isolates were identified as AmpC producer using combined disk method. Fifty two isolates showed a twofold or threefold dilution difference between the minimum inhibitory concentration of imipenem or ceftazidime and the minimum inhibitory concentration of imipenem or ceftazidime plus cloxacillin. One isolate was identified as AmpC producer using three methods. Three isolates produced AmpC as detected by both AmpC disk test and combined disk methods and 19 isolates were found as AmpC producer using both AmpC disk test and minimum inhibitory concentration methods. Six isolates were AmpC producer as shown by the MICs of both imipenem and ceftazidime. CONCLUSION: According to the results of this study, AmpC- beta-lactamase looks to be the main mechanism of resistance of Pseudomonas aeruginosa to cephalosporins and carbapenems in the study hospital

Methane emissions abatement by multi-ion-exchanged zeolite A prepared from both commercial-grade zeolite and coal fly ash

The performance of multimetal-(Cu, Cr, Zn, Ni, and Co)-ion-exchanged zeolite A prepared from both a commercial-grade sample and one produced from coal fly ash in methane emissions abatement was evaluated in this study. The ion-exchange process was used to load the metal ions in zeolite A samples. The methane conversion efficiency by the samples was studied under various parameters including the amount of metal loading (7.3-19.4 wt%), reaction temperature (25-500°C), space velocity (8400-41 900 h-1), and methane concentration (0.5-3.2 vol %). At 500°C, the original commercial-grade zeolite A catalyzed 3% of the methane only, whereas the addition of different percentages of metals in the sample enhanced the methane conversion efficiency by 40-85%. Greater methane conversion was observed by increasing the percentage of metals added to the zeolite even though the BET surface area of the zeolite consequently decreased. Higher percentage methane conversion over the multi-ion-exchanged samples was observed at lower space velocities indicating the importance of the mass diffusion of reactants and products in the zeolite. Compared to the multi-ion-exchanged zeolite A prepared from the commercial-grade zeolite, the one produced from coal fly ash demonstrated similar performances in methane emissions abatement, showing the potential use of this low cost recycled material in gaseous pollutant treatment