Journal of Isfahan Medical School

Journal of Isfahan Medical School

Determining the Patterns of Antimicrobial Susceptibility and the Distribution of blaCTX-M Genes in Strains of Acinetobacter Baumannii Isolated from Clinical Samples

Document Type : Original Article (s)

Authors
Somayeh Vafaei 1
Reza Mirnejad 2
Noor Amirmozafari 3
1 Department of Biology, Islamic Azad University, Science and Research Branch, Tehran, Iran
2 Assistant Professor, Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
3 Associate Professor, Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
Abstract
Background: Nowadays, multidrug resistant (MDR) Acinetobacter baumannii (A. baumannii) strains are as one of the problematic opportunistic pathogens, especially in intensive care units in the world. The purpose of current study was to define the antibiotic susceptibility patterns and detect the prevalence of producing strains of extended-spectrum β-lactamase (ESBL) and the appearance of betalactamase CTX-M-II enzymes in A. baumannii strains.Methods: This study was conducted in 3 major hospitals in Tehran, Iran, on 500 clinical samples during one year. After the identification of isolates in species, test sensitivity was carried out to 4 antibiotics by using the disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) guidelines; also minimum inhibitory concentrations (MIC) was determined for cefepime, cefotaxime and ceftazidime; and finally, to identify the producing strains of ESBL, phenotypic method of combined-disk was used and then, isolates were considered for presence of blaCTX-M-II gene by polymerase chain reaction (PCR) assay.Findings: 130 Acinetobacter species were isolated from the patients. The majority of isolates was from blood specimens and revealed the highest resistance to cefepime and ceftriaxone. The MIC of cefepime in 91%, for ceftazidime in 84%, and for cefotaxime in 80% of the studied isolates was more than 128 μg/ml. The results of the combined-disk test demonstrated that 20% of samples were ESBL positive. The PCR results showed that 19% of our isolates had bla CTX-M-II gene.Conclusion: Multidrug resistant (MDR) A. baumannii is widespread in Iran and is considered as hazard risk for hospitalized patients; also by virtue of the results of this survey, there are more significant mechanisms than ESBL bacteria such as secretory pumps and changes in purine resistance which causes more resistance, too, and should be consider.
Keywords
Acinetobacter baumannii
Extended-spectrum β-lactamase (ESBL)
Antibiogram
Combined-disk
CTX-M-II gene
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Journal of Isfahan Medical School
Volume 31, Issue 252 - Serial Number 252
July and August 2013
Pages 1443-1451

  • Receive Date 24 April 2013
  • Accept Date 06 April 2022