Bacteriological And Genetic Study On Extended-spectrum Beta-lactamases And Bacteriocins Of Klebsiella Isolated From Hilla City, Iraq  

Abstract Category: Science
Course / Degree: Ph.D
Institution / University: College of Science/Babghdad University, Iraq
Published in: 2005

Dissertation Abstract / Summary:

The present study included 298 samples (89 environmental and 209 clinical samples) collected from different sites in one of the Middle Euphrates areas during the period from January to July 2003. Clinical samples were collected from the main three hospitals in Hilla (Teaching hospital, Margan hospital, Maternity and pediatric hospital), in addition to General Health Lab, and some private laboratories in Hilla, Iraq Results of morphological and biochemical characterization tests revealed that a total of 88 isolates were belonged to genus Klebsiella. All Klebsiella isolates were identified to the level of subspecies for the first time in Iraq. It was found that 84 isolates belonged to K. pneumoniae and only four isolates were K.oxytoca. However, K.pneumoniae subsp. pneumoniae was predominant (87%), followed by K. pneumoniae subsp. ozaenae (9.5 %) and K. pneumoniae subsp. rhinoscleromatis (3.5 %). Results of primary screening of β- Lactam resistant isolates showed that 65 Klebsiella strains (73.8 % ) were resistant to both ampicillin and amoxicillin, of which only 38 ( 58.4 % ) gave positive results with rapid iodometric method used for the detection of β- lactamase enzyme .Such ratio indicates that the enzymatic resistance was prevalent among β- lactam resistant Klebsiella isolates. All 38 β- lactamase- producing Klebsiella isolates were tested for their antibiotic resistance against 21 antibiotics. They were found to be resistant, to least , 8 antibiotics. Hence, all these resistant isolates were considered multidrug resistant, when 100 % of them were resistant to penicillin , ampicillin, and amoxicillin. For third generation cephalosporins, more than 73 % of Klebsiella isolates were resistant to ceftizoxime and 50 % to cefotaxime, but they showed very low level of resistance to ceftazidime (18.4 %) and ceftriaxone (34.2 % ). Results also showed that Klebsiella isolates were highly resistant to gentamycin (81.5 % ), tetracycline (63.1 % ), and erythromycin (52.6 % ) but they were highly sensitive to rifampin. Klebsiella isolates were also tested for their ability to produce Extended-Spectrum Beta-lactamases ( ESBLs ) using three methods. Determination of Minimum inhibitory concentration ( MIC ) with and without clavulanate was the most accurate method for detection of ESBL- producing isolates, while the disk approximation was the least accurate method in detecting such enzymes. MICs of ESBL-producer isolates against 8 β-lactam antibiotics showed that all 8 ESBL- producing Klebsiella isolates were highly resistant for both ampicillin and amoxicillin. They were also resistant to ceftazidime, ceftizoxime, and ceftriaxone but not for cefotaxime. The high MIC results ( from 64 to >128 μg/ml ) of Klebsiella isolates in the present study suggest that ESBL enzymes are endemic in the area of the study. Results of detection of klebocin production by klebsiella isolates showed that 62.5 % of them were klebocin-producers . It was also found that brain heart infusion agar medium supplemented with 5 % glycerol was the best culture medium used for detection of klebocin-producing isolates and cup assay was the best method used for such purpose. Results also revealed that klebocins of Klebsiella isolates had a broad antimicrobial spectrum and active, in addition to Klebsiella strains, on many pathogenic species of Gram-negative and some Gram-positive bacteria. Agarose gel electrophoresis of DNA samples of some selected Klebsiella isolates showed that they harbor plasmid bands different in size and position. Results of conjugation experiments revealed that genes encoding for the production of klebocin and resistance to penicillin, ampicillin, amoxicillin, expanded-spectrum β- lactam antibiotics, tetracycline, refampin, and erythromycin were located on conjugative plasmids whereas genes encoding for resistance to cephalothin, cefazolin, cephalexin, and gentamycin could be located on the chromosome because they did not transfer from donor to recipient cells by conjugation.

Dissertation Keywords/Search Tags:
Klebsiella pneumoniae, ESBL, Bacteriocin, Iraq

This Dissertation Abstract may be cited as follows:
Al-Charrakh A.H. (2005). Bacteriological and Genetic Study on Extended-Spectrum Beta-Lactamases and Bacteriocins of Klebsiella isolated from Hilla city, Iraq. Ph.D thesis. College of Science,Baghdad University, Iraq

Submission Details: Dissertation Abstract submitted by Alaa Al-Charrakh from Iraq on 28-Jun-2012 21:17.
Abstract has been viewed 3160 times (since 7 Mar 2010).

Alaa Al-Charrakh Contact Details: Email: ahani67@gmail.com

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