Occurrence and mechanisms of resistance to b-lactam antibiotics in multiresistant Acinetobacter spp. clinical isolates

Abstract number: 1733_1154

Sodomova E., Michalkova-Papajova D., Gottwaldova B., Rovna D.

Objectives: The aim of the study was to determine the occurrence and mechanisms of resistance to b-lactam antibiotics in multiresistant clinical isolates of the genus Acinetobacter.

Methods: Clinical isolates included in the study (n = 111) were obtained from University Hospital Ruzinov, Bratislava (Slovakia) and identified by NEFERMtest24 (Pliva-Lachema, Czech Republic). Resistance to antimicrobial agents was determined by standard disk diffusion method according to NCCLS. The production of ESBL was detected by combination disk method with disk combinations: ceftazidime (30 mg) and ceftazidime-clavulanic acid (30/10 mg), cefotaxime (30 mg) and cefotaxime-clavulanic acid (30/10 mg), cefepime (30 mg) and cefepime-clavulanic acid (30/10 mg). The presence of the genes coding for TEM- and SHV-type b-lactamases was determined by PCR.

Results: In the set of 111 Acinetobacter spp. isolates 100.0% were resistant to mezlocillin, 81.1% to ticarcillin, 99.1% to piperacillin, 99.1% to carbenicillin, 35.1% to ampicillin-sulbactam, 55.9% to piperacillin-tazobactam, 64.0% to ticarcillin-clavulanic acid, 81.1% to ceftazidime, 47.7% to cefepime, 100.0% to cefoperazone, 91.9% to cefotaxime, 91.0% to ceftriaxone, 94.6% to ceftizoxime, 91.9% to moxalactam, 0.0% to imipenem, 20.7% to meropenem, 73.9% to aztreonam, 96.4% to gentamicin, 55.0% to amikacin, 15.3% to tobramycin, 20.7% to netilmicin, 96.4% to tetracycline, 72.1% to doxycycline, 74.8% to minocycline, 98.2% to ciprofloxacin, 91.9% to levofloxacin, 99.1% to lomefloxacin, 99.1% to norfloxacin, 80.2% to ofloxacin, 92.8% to gatifloxacin, 99.1% to chloramphenicol, 77.5% to trimethoprim-sulfamethoxazole and 90.1% to sulfonamides. In the presence of cloxacillin (inhibitor of class C cephalosporinases, 200 mg/mL) at least 5 mm increase in a zone diameter in 67.6% of the isolates for ceftazidime, 82.9% for cefotaxime and 17.1% for cefepime was observed. Only one isolate (0.9%) was detected as ESBL-producer. The presence of the genes coding for TEM-type b-lactamases was determined in all clinical isolates tested, but the presence of the genes coding for SHV-type b-lactamases was determined only in two clinical isolates (1.8%).

Conclusion: Most of the Acinetobacter spp. clinical isolates (91.0%) were resistant to 20 or more from 33 antimicrobial agents tested. Only imipenem was effective to all isolates. The production of b-lactamases contributed to frequent occurrence of resistance to b-lactam antibiotics.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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