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Antimicrobial susceptibilities of Gram positive bacteria and antibiotic consumption in a Greek tertiary hospital, 20012008

Abstract number: R2157

Objective: To examine differences in antibiotic susceptibility of Gram positive bacteria and in antibiotic consumption in a Tertiary Hospital, within 7 years of operation.

Methods: All clinical samples from inpatients. Identification and susceptibility testing, using the Wider® semi-automated system with CLSI breakpoints. Antibiotic consumption expressed as Defined Daily Doses (DDD) per patient-day.

Results: 841 and 413 isolates identified during 2008 and 2001, respectively.

Methicillin Resistant S. aureus (MRSA) rates were significantly higher in 2008 (56.5%, 74/131 isolates) than in 2001 (36.6%, 15/41; p = 0.026). The proportion of community-acquired strains among MRSA also increased in 2008 (32.4%, 24/74 vs. 26.3%, 4/15 in 2001). One MRSA in 2008 had reduced susceptibility to Vancomycin (MIC=8); and 1 to Linezolid (MIC > 4). No such strains were found in 2001.

S. aureus resistance increased for Penicillin (121/131 isolates, 92.4% in 2008 vs. 30/40, 75% in 2001; p < 0.01), Erythromycin (53.8% vs. 35.9%; p < 0.05) and Clindamycin (42% vs. 32.5%).

Among hospital strains (>48 hours from admission) Coagulase-Negative Staphylococci (CoNS) resistance to Methicillin increased in 2008 (81%, 222/274 isolates vs. 72.4%, 121/167 in 2001; p < 0.04). CoNS in 2008 had high rates of non-susceptibility to several antibiotics tested (ranging from 47.1% for Cotrimoxazole to 92.3% for Penicillin). 4 CoNS strains were non-susceptible to Vancomycin in 2008, and 1 in 2001. All CoNS were susceptible to Linezolid.

Non-susceptibility rates of Enterococcus sp. hospital strains increased for Amoxycillin/Clavulanate (37.4%; 49/131 isolates in 2008 vs. 22.2%; 14/63 in 2001, p = 0.035), Erythromycin (87.8% vs. 82.5%) and Rifampicin (70.3% vs. 64.8%). 2/192 Enterococci in 2008 were resistant to Vancomycin (VRE) and Teicoplanin (VanA phenotype). 9/192 Enterococci in 2008 had MIC geqslant R: gt-or-equal, slanted2 to Linezolid.

There was only 1 S. pneumoniae isolate (non-CNS) with Penicillin MIC=2 in 2008; all S. pneumoniae isolated in 2001 had MICleqslant R: less-than-or-eq, slant;0.12.

Consumption of wide-spectrum antibiotics increased by 28.8% (17.9 DDD/100 hospital-days in 2008 vs. 13.9 in 2001). Consumption of anti-MRSA antibiotics also increased (1.94 in 2008 vs. 1.64 in 2001).

Conclusion: Within 7 years, there was a marked increase of non-susceptibility rates of Gram-positive bacteria, including MRSA. This paralleled the increased consumption of wide-spectrum antibiotics and of antibiotics with activity against multi-resistant Gram-positive bacteria.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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