Summary

Introduction: Acinetobacter species can cause health care-associated infections in patients who are treated in intensive care units of hospitals. The aim of this study was to determine the antibiotic resistance rates of Acinetobacter species that induce health care-associated infections among intensive care unit patients in a state hospital during the period 2008-2011.

Materials and Methods: Clinical samples obtained from intensive care unit patients were cultured by regular methods. The identification and antibiotic susceptibility tests were performed using the BD Phoenix 100 system, BD Phoenix NMIC/ID-82 Id+ADT (Becton Dickinson, Belgium).

Results: During the study period a total of 320 Acinetobacter strains were isolated. Colistin and tigecycline were found to be the most effective antimicrobial agent against Acinetobacter species. When the resistance rates were compared between 2008 and 2011, significant increases were observed for imipenem, meropenem, ceftazidime, trimethoprim-sulfamethoxazole, and ampicillin- sulbactam; a significant decrease was observed for tobramycin. No statistically significant changes were observed for amikacin, cefepime, ceftriaxone, piperacillin-tazobactam, and gentamicin.

Conclusion: High antibiotic resistance rates of Acinetobacter species induce health care- associated infections in intensive care unit patients. It is important to undertake bacteriologic surveillance in hospitals to ascertain the common microorganisms and their antibiotic resistance rates.

Keywords:

Acinetobacter, antibiotic resistance, health care-associated infection, nosocomial

Introduction

In this study, it was aimed to determine the antibiotic resistance rates of Acinetobacter strains isolated from clinical specimens of ICU patients and the distribution of these ratios during the period 2008-2011.

Methods

A prospective and active surveillance was performed among patients treated in a state hospital ICU between 2008 and 2011. The diagnosis of health careassociated infection was based on the Centers for Disease Control and Prevention (CDC) criteria[7]. A total of 320 Acinetobacter spp. isolated from the patients who had health care-associated infection in the ICU and the antibiotic resistance of the isolates were investigated in the study. The samples were inoculated on 5% sheep blood agar and EMB agar. The identification and antibiotic susceptibility tests were performed using the BD Phoenix 100 system, BD Phoenix NMIC/ID-82 Id+ADT (Becton Dickinson, Belgium). Strains defined as Acinetobacter spp. were evaluated for resistance to antimicrobials. Statistical analysis was performed with the Statistical Package for the Social Sciences (SPSS) for Windows (SPSS Inc., Chicago, IL, USA) program and the non-parametric chi-square test.

Results

Table 1: The distribution of the Acinetobacter strains

Table 2: The distribution of the samples (%)

We determined the antibiotic resistance rates for a four-year average as follows: 93.4% for ceftazidime, 93.2% for cefepime, 93.1% for ceftriaxone, 92.6% for ciprofloxacin, 91.4% for gentamicin, 89.4% for ampicillin- sulbactam, 88.9% for piperacillin-tazobactam, 88.9% for amikacin, 84.5% for tetracycline, 87.9% for trimethoprim-sulfamethoxazole, 68.5% for meropenem, 67.6% for cefoperazone-sulbactam, 65.8% for imipenem, 37% for tobramycin, 2.5% for colistin, and 10% for tigecycline (Figure 1).

Figure 1: Antibiotic resistance rates of Acinetobacter strains (%).

The annual distribution of these ratios is shown in Table 3. When the resistance rates were compared between 2008 and 2011, significant increases were observed for imipenem (p< 0.001), meropenem (p< 0.001), ceftazidime (p< 0.001), trimethoprim-sulfamethoxazole (p< 0.01), and ampicillin-sulbactam (p< 0.05). Further, significant increases were observed for cefoperazone-sulbactam between 2009 and 2011. Although a significant decrease was observed for tobramycin (p< 0.001), we found no statistically significant changes for amikacin, cefepime, ceftriaxone, piperacillin-tazobactam, and gentamicin (Table 3).

Table 3: Antibiotic resistance rates of Acinetobacter strains between years 2008-2011 (%)

Discussion

Table 4: Antibiotic resistance rates of Acinetobacter strains isolated from various ICU patients (%)

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