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  Table of Contents  
Year : 2013  |  Volume : 31  |  Issue : 4  |  Page : 415-416

Occurrence and characterisation of CTX-M enzymes in Enterobacteriaceae isolated from intensive care units of a Turkish University hospital

1 Department of Medical Microbiology, Hacettepe University, Ankara, Turkey
2 Faculty of Medicine, School of Health Services, Medical Laboratory Program, Hacettepe University, Ankara, Turkey

Date of Submission18-Dec-2012
Date of Acceptance26-Jul-2013
Date of Web Publication25-Sep-2013

Correspondence Address:
K Eser
Department of Medical Microbiology, Hacettepe University, Ankara
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0255-0857.118881

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How to cite this article:
Eser K, Ergin A, Hascelik G. Occurrence and characterisation of CTX-M enzymes in Enterobacteriaceae isolated from intensive care units of a Turkish University hospital. Indian J Med Microbiol 2013;31:415-6

How to cite this URL:
Eser K, Ergin A, Hascelik G. Occurrence and characterisation of CTX-M enzymes in Enterobacteriaceae isolated from intensive care units of a Turkish University hospital. Indian J Med Microbiol [serial online] 2013 [cited 2020 Dec 3];31:415-6. Available from:

Dear Editor,

We have performed the molecular analysis of extended spectrum beta-lactamases (ESBL) in particular CTX-M genes and antibiotic resistance integrons among Klebsiella pneumoniae,  Escherichia More Details coli and Enterobacter spp. strains isolated from patients in intensive care units (ICUs). Randomly selected nonduplicate 117 isolates of E. coli, Klebsiella spp. and Enterobacter spp. were collected from patients admitted to the ICUs of Hacettepe University Hospital through 7 years.

Antimicrobial susceptibility testing was performed by agar dilution method in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. [1] ESBL production was detected by combined disk diffusion. Polymerase chain reaction (PCR) method was used to detect blaTEM , blaSHV , blaCTX-M genes. [2],[3] Sequencing of all positive blaCTX-M isolates were determined. PCR amplification was performed for the detection of class 1 integron cassettes. [4]

Among 117 isolates, frequency of ESBL was found as 41 (35.0%) by combined disk diffusion method. Among 41 ESBL positive isolates, 35 (85.4%) had blaTEM , 33 (80.5%) blaSHV and 20 (48.8%) blaCTX-M . Analysis of nucleotide sequences of blaCTX-M showed that 20 isolates of K. pneumoniae and E. coli and Enterobacter spp. harboured blaCTX-M-3 and blaCTX-M-15 [Table 1]. Class 1 integron was identified in 69.9% of all isolates. Of 41 ESBL positive isolates, 20 were found to produce CTX-M type ESBL and all these also carried class 1 integron, suggesting an association between integrons and ESBL carriage among Enterobacteriaceae. We have no clear reason for the existence of CTX-M-3 and -15 among isolates but indiscriminate use of cephalosporins and quinolones or unrestricted policy of antimicrobial usage might be the causative factors. It is notable that E. coli and K. pneumoniae with CTX-M-3 and CTX-M-15 enzymes in our hospital are the most frequent CTX-M types resembling CTX-Ms widely reported from Poland which have spread through whole Europe. [5]
Table 1: Frequency of bla genes among 41 ESBL positive isolates

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Resistance rates of all antibiotics studied were high, leaving carbapenems as the last choice of drug in the treatment of ESBL producing gram-negative nosocomial infections. These results indicate that as ESBL production and rates of resistance to many antibiotics are high in ICUs. This consequence highlights the value of restriction policies in antibiotic use for an appropriate therapy of infections caused by ESBL producers.

 ~ Acknowledgments Top

This study was supported by a grant of Hacettepe University Scientific Researches Unit, Ankara Turkey (Project No. 03D06101001) and a grant of the Scientific and Technological Research Council of Turkey (Project No. SBAG-AYD-328).

 ~ References Top

1.Clinical and Laboratory Standards Institute (CLSI). Performance standards for antimicrobial susceptibility testing. 21 st informational supplement: M100-S21 2011.  Back to cited text no. 1
2.Edelstein M, Pimkin M, Palagin I, Edelstein I, Stratchounski L . Prevalence and molecular epidemiology of CTX-M extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae in Russian hospitals. Antimicrob Agents Chemother 2003;47:3724-32.  Back to cited text no. 2
3.Paterson DL, Hujer KM, Hujer AM, Yeiser B, Bonomo MD, Rice LB, et al. International Klebsiella Study Group. Extended spectrum beta-lactamases in Klebsiella pneumoniae bloodstream isolates from seven countries: Dominance and widespread prevalence of SHV and CTX-M-type beta-lactamases. Antimicrob Agents Chemother 2003;47:3554-60.  Back to cited text no. 3
4.Martinez-Freijo P, Fluit AC, Schmitz FJ, Grek VS, Verhoef J, Jones ME. Class 1 integrons in Gram-negative isolates from different European hospitals and association with decreased susceptibility to multiple antibiotic compounds. J Antimicrob Chemother 1998;42:689-96.  Back to cited text no. 4
5.Livermore DM, Canton R, Gniadkowski M, Nordmann P, Rossolini GM, Arlet G, et al. CTX-M: Changing the face of ESBLs in Europe. J Antimicrob Chemother 2007;59:165-74.  Back to cited text no. 5


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