year 2, Issue 2 (Summer 2008)
Iran J Med Microbiol 2008, 2(2): 49-54 |
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Abbasi S, Mansouri S. Accuracy of identification and susceptibility tests of gram negative bacilli performed routinely by clinical laboratories compared to the standard procedures in Kerman. . Iran J Med Microbiol 2008; 2 (2) :49-54
URL: http://ijmm.ir/article-1-120-en.html
URL: http://ijmm.ir/article-1-120-en.html
1- Department of Microbiology, Medical Sciences University of Kerman
2- Department of Microbiology, Medical Sciences University of Kerman , shmansouri_1000@yahoo.com
2- Department of Microbiology, Medical Sciences University of Kerman , shmansouri_1000@yahoo.com
Abstract: (28746 Views)
Background and aim: Gram–negative rods are the most common bacterial isolates in clinical laboratories
around the word. Quick and accurate identification of these bacteria is a key to the effective therapeutic
intervention and optimal clinical out come of infections caused by these bacteria. Multiple drug resistance
gram-negative bacteria (MDR) are on increase and are reported frequently. Since in many clinical
laboratories the standard antibiogram tests are not performed and very few tests are used for identification .
The aim of this study was to evaluate the accuracy of identification and the susceptibility tests of gram
negative bacilli performed by clinical laboratories compared to the standard procedures in Kerman.
Materials and Methods: This study was performed on 948 clinical isolates reported to have the MDR phenotypes by disk diffusion method. The isolates were identified to species level by conventional biochemical tests. Sensitivity of the isolates to antibacterial agents and the Minimum Inhibitory concentration (MIC) of the isolates were determined using agar dilution method. For statistical analysis, X2 test was used.
Results: The rate of isolation of MDR bacteria by agar dilution methods was 76% of those reported by disk diffusion methods. For all antibiotics disk diffusion showed higher rate of resistance compared with agar dilution. The difference in case of tetracycline, gentamicin, ciprofloxacin, amoxicillin and cephalosporins (ceftizoxime, ceftazidime) and trimethoprime-sulfamethoxazole were significant (P=0.002). In the centers under study lower rate was reported for the isolation of Enterobacter spp and citrobacter spp ,while Escherichia coli and Klebsiella spp were reported more than their actual presence.
Conclusion: These results showed that the laboratory reports were relatively accurate. However since higher rate of bacterial resistance were reported by the disk diffusion methods, in case of serious and life threatening infections suitable drug for treatment should be confirmed by more sensitive tests. In the absence of suitable and low cost detection kits for the identification of gram negative bacilli, inaccurate identifications is an avoidable, therefore immediate action to design the accurate and low cost kits for the identification of these bacteria is recommended in the country.
Materials and Methods: This study was performed on 948 clinical isolates reported to have the MDR phenotypes by disk diffusion method. The isolates were identified to species level by conventional biochemical tests. Sensitivity of the isolates to antibacterial agents and the Minimum Inhibitory concentration (MIC) of the isolates were determined using agar dilution method. For statistical analysis, X2 test was used.
Results: The rate of isolation of MDR bacteria by agar dilution methods was 76% of those reported by disk diffusion methods. For all antibiotics disk diffusion showed higher rate of resistance compared with agar dilution. The difference in case of tetracycline, gentamicin, ciprofloxacin, amoxicillin and cephalosporins (ceftizoxime, ceftazidime) and trimethoprime-sulfamethoxazole were significant (P=0.002). In the centers under study lower rate was reported for the isolation of Enterobacter spp and citrobacter spp ,while Escherichia coli and Klebsiella spp were reported more than their actual presence.
Conclusion: These results showed that the laboratory reports were relatively accurate. However since higher rate of bacterial resistance were reported by the disk diffusion methods, in case of serious and life threatening infections suitable drug for treatment should be confirmed by more sensitive tests. In the absence of suitable and low cost detection kits for the identification of gram negative bacilli, inaccurate identifications is an avoidable, therefore immediate action to design the accurate and low cost kits for the identification of these bacteria is recommended in the country.
Type of Study: Original Research Article |
Subject:
Medical Bacteriology
Received: 2013/11/15 | Accepted: 2013/11/15 | ePublished: 2013/11/15
Received: 2013/11/15 | Accepted: 2013/11/15 | ePublished: 2013/11/15
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