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Prevalence and epidemiology of antibiotic resistance in Pseudomonas aeruginosa isolated from low respiratory tract of patients hospitalised in intensive care units from 5 Belgian hospitals, 20042008

Abstract number: P1502

Riou M., Carbonnelle S., Avrain L., Glupczynski Y., De Vos D., Pirnay J.-P., Simon A., Pierard D., Jacobs F., Dediste A., Van Bambeke F., Tulkens P.

Objectives:Pseudomonas aeruginosa (PA) is a major cause of nosocomial infections, with one of its preferential "niches" in respiratory tract of patients in ICU. Our objective was to evaluate the level of resistance of PA towards commonly used antibiotics in this setting.

Methods: 138 first, non-duplicate isolates were collected from 5 hospitals over the last 4 years from ICU patients with a suspicion of nosocomial pneumonia (confirmed in most cases by retrospective analysis of medical records). MICs of 5 commonly used antibiotics plus ticarcillin and aztreonam (as efflux reporters) were determined by geometric microdilution in cation-adjusted Muller-Hinton broth. Susceptibility was assessed according to EUCAST Breakpoints (BP).

Results: Based on EUCAST breakpoints, and using a 20% resistance cut-off, only amikacin could be considered effective globally as well as in each individual hospital. Meropenem was globally effective, but resistance exceeded the cut-off in 3/5 hospitals. Gentamicin, aztreonam, ciprofloxacin and cefepime were globally ineffective, with resistance exceeding 40% for cefepime in 2 hospitals (cefepime-resistant isolates were also often resistant to other antibiotics [GEN, 24%; AMK; 8%; ATM, 27%; MEM, 20%; and CIP, 20%]).

Conclusion: The level of antibiotic resistance in Pseudomonas aeruginosa (including cross-resistance, as illustrated for cefepime) in the ICU surveyed is critically limiting therapeutic options, but in variable way that justifies early and careful assessment of susceptibilities for ensuring appropriate therapy. Efflux-mediated resistance seems also very prevalent and will need appropriate diagnostic approaches.

 GlobalH1 (n = 12)H2 (n = 30)H3 (n = 18)H4 (n = 22)H5 (n = 56)
 MIC50/90I/R (%)aMIC50/90I/R (%)aMIC50/90I/R (%)aMIC50/90I/R (%)aMIC50/90I/R (%)aMIC50/90I/R (%)a
GEN2/640.0/252/640.0/252/640.0/304/640.0/332/320.0/272/80.0/20
AMK4/169.4/8.04/80.0/8.34/3213/138/1611/5.64/3218/148/83.6/5.4
MEM1/160.0/101/425/8.32/166.7/371/417/5.61.0/164.5/271/1616/27
FEP8/640.0/464/320.0/3316/640.0/7012/640.0/446/640.0/368/640.0/37
CIP0.25/87.2/220.25/88.3/250.4/166.7/370.25/1611/330.19/80.0/140.19/168.9/16.1
             
TIC64/5120.0/87.032/2560.0/78128/2560.0/8364/2560.0/8048/5120.0/9164/5120.0/90
ATM12/3267/306.0/3267/3316/3267/3316/3256/3316/12864/368/3275/23
aEUCAST breakpoints: gentamicin (GEN): Sleqslant R: less-than-or-eq, slant4, R>4; amikacin (AMK): Sleqslant R: less-than-or-eq, slant8, R>16; meropenem (MEM): Sleqslant R: less-than-or-eq, slant2, R>8; cefepime (FEP): Sleqslant R: less-than-or-eq, slant8, R>8; ciprofloxacin (CIP): Sleqslant R: less-than-or-eq, slant0.5, R>1; ticarcillin (TIC): Sleqslant R: less-than-or-eq, slant16, R>16: aztreonam [ATM]: Sleqslant R: less-than-or-eq, slant1, R>16.
Figures in bold indicate situations (global or per hospital) in which resistance to a clinically-used given antibiotic exceeds 20% of isolates.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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