Antibiotic resistance pattern among nonfermenting gram-negative bacteria isolated from clinical specimens during 2007-2008 in Kerman, IRAN

Razavi, Mojdeh; Mansouri, Shahla; Norouzi, Fatemeh

year 4, Issue 4 (Winter 2011) Iran J Med Microbiol 2011, 4(4): 7-13 | Back to browse issues page

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Razavi M, Mansouri S, Norouzi F. Antibiotic resistance pattern among nonfermenting gram-negative bacteria isolated from clinical specimens during 2007-2008 in Kerman, IRAN. Iran J Med Microbiol 2011; 4 (4) :7-13
URL: http://ijmm.ir/article-1-21-en.html

Antibiotic resistance pattern among nonfermenting gram-negative bacteria isolated from clinical specimens during 2007-2008 in Kerman, IRAN

Mojdeh Razavi¹

, Shahla Mansouri

², Fatemeh Norouzi¹

1- Department of Microbiology, Islamic Azad University, Qum branch
2- Department of Microbiology, School of Medicine, Kerman University of Medical Sciences

Abstract: (32345 Views)

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Background: Nonfermenting Gram-Negative Bacteria (NFGNB) are opportunistic pathogens responsible for many nosocomial infections. The most prevalent NFGNB species are Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia. These bacteria expressed high level of resistance to antibiotics usually through the most general mechanism of resistance by production of Extended-Spectrum β-lactamases (ESBLs). The present study was conducted to determine the prevalence rate of NFGNB, their antibiotic resistances and ESBLs production during 2007-2008 in Kerman.

Material and Methods: A total of 110 NFGNB isolates from hospitalized patients and outpatients (Afzali Poor, Bahonar, and Shafa hospitals) were collected during 2007-2008 in Kerman. The isolates were identified by biochemical methods as 93 isolates (84.5%) of Pseudomonas aeruginosa, 11 isolates (10%) of Stenotrophomonas maltophilia and 6 isolates (5.5%) of Acinetobacter baumannii. The minimum inhibitory concentrations (MICs) of the isolates to 11 common antibiotics were determined using agar dilution method. These isolates are capable of producing β-lactamase, and they were determined using nitrocefin disks. The ESBL producing isolates were detected by DCDT method (double disk test & combined disk test).

Results: P. aeruginosa was the most common isolate among all isolated NFGNB. Resistance to cefotaxime, ceftizoxime, nalidixic acid, amoxicillin, cephalexin, for all the isolates was very high (74-100%), whereas the lowest rate of resistance was observed against imipenem, ceftazidime and ciprofloxacin with the rate of 0.9%, 13.6% and 24.5% respectively. β-lactamase production was positive for 50 (45.5%) of the isolate and 47.2% of the isolate were ESBL producers. Antibiotic resistance, β-lactamase and ESBL production were more common in Acinetobacter baumannii isolates.

Conclusion: NFGNB, especially Acinetobacter baumannii , showed high antibiotic resistance to common drugs. Ceftazidime and imipenem are still useful antibiotics and they can be used for the treatment of infections caused by these bacteria.