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P2037 In vitro antibacterial activity of tigecycline against anaerobic hospital isolates;comparison of two methods in France: a multicentre study
In vitro susceptibility: tigecycline
S587
Conclusion: MICs of TIG obtained by both methods (A and B) appeared identical or very similar. The susceptibility zone diameter breakpoint recommended in France by using the 15 mg TIG disks could be 22 mm for all species. However, for Enterobacteriaceae, except Proteus, Morganella and Providencia showing a poor susceptibility to TIG, MICs should be determined on isolates with zone diameter <22 mm.
P2037 In vitro antibacterial activity of tigecycline against anaerobic hospital isolates; comparison of two methods in France: a multicentre study L. Dubreuil, L. Calvet, V. Jarlier, J. Cavallo, M. Chomarat, H. Drugeon, M. Kitzis, C. Soussy, C. Lascols, M. Roussel-Delvallez, C. Muller-Serieys, R. Leclercq, J. Rolain, A. Dubanchet (Lille, Paris, Saint-Mand´e, Lyon, Nantes, Cr´eteil, Caen, Marseilles, FR) Objectives: The aim of the study was to compare the MICs of tigecycline (TIG) by agar dilution (A) using the Clinical Laboratory Standards Institute (CLSI) M11 A6 method and a disk-diffusion test using the Comit´e de l’Antibiogramme de la Soci´ete Fran¸caise de Microbiologie (CA-SFM) method and to propose zone diameter breakpoints for clinical categorisation in France. Methods: MICs of TIG were determined by the reference agar method M11A6 against 230 strains collected in 10 university hospitals in France in 2006. Antibiograms were performed with 15 mg disks, according to the CA-SFM method on Brucella blood agar. An internal quality control was carried out with B. fragilis ATCC25285, B. thetaiotaomicron ATCC 29741 and Eggerthella lenta ATCC 43055. Results: Results for TIG are shown in the table. By disk-diffusion test the range for the inhibition zones were 28−41 mm for GPAC, 21−37mm for clostridia (with exception of C. perfringens inhibition zone 14−35 mm), and 11−40 mm for the B. fragilis group. Considering the 4 mg/L CLSI breakpoint, the susceptibility zone diameter breakpoint recommended in France by using the 15 mg TIG disks could be ? 21 mm for all species except C. perfringens. MIC should be determined on isolates with zone size diameter <20 mm.
Bacterial species
Bacteroides fragilis (84) Bacteroides thetaiotaomicron (14) Other Bacteroides (19) All Bacteroides of the fragilis group (117) Prevotella spp. (4) C. perfringens (48) C. difficile (18) Other clostridia (6) Finegoldia magna (13) Micromonas micros (10) Other GPAC: Gram-positive cocci (14) All Gram-positive anaerobes (109) All anaerobes (230)
MIC (mg/L) Range
MIC50 MIC90
0.06−16 0.06−16 0.06−2 0.06−16 0.06–0.125 0.06−2 0.06–0.25 0.06−0.5 0.06−0.5 0.06−0.5 0.06−0.5 0.06−2 0.06−16
0.5 2 0.25 0.5 ND 0.5 0.125 0.5 0.125 0.125 0.125 0.125 0.25
2 16 1 2 ND 1 0.25 0.5 0.25 0.25 0.25 1 2
Conclusion: Categorisation by disk-diffusion test remains difficult for anaerobes. Among the B. fragilis group, resistance to metronidazole or imipenem could not be detected, but decreased susceptibility to metronidazole (4.3%) was observed. TIG 4 mg/L inhibited 111/117 strains of the B. fragilis group meanwhile TIG 2 mg/L was able to inhibit all Gram-positive anaerobes. Thus, at a concentration of 4 mg/L, TIG inhibited 97.3% of the investigated strains.
P2038 In vitro activity of tigecycline against linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates A. Stylianakis, A. Koutsoukou, S. Tsiplakou, S. Sardiniari, A. Vourtsi, I. Merianos (Athens, GR) Objectives: The purpose of our study was to evaluate the in vitro activity of tigecycline against linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. Methods: We examined 18 non duplicated linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. These isolates were recovered from blood cultures of ICU patients of our hospital during a 12 months time period. The identification and the susceptibility testing of the isolates were performed by the automated VITEK 2 system (boiM´erieux, France). The susceptibility testing for tigecycline was performed by Kirby-Bauer disk diffusion method and done by direct colony suspension according to CLSI guidelines. Paper disks containing tigecycline at 15 mg per disk were used (Becton-Dickinson, USA). The determination of tigecycline and linezolid MIC values was performed by using E-test strips according to the manufacturer’s guidelines (ABBiodisk, Sweden). Isolates with an inhibition zone diameter of 19 mm and with an MIC level 0.5 mg/L were considered as susceptible to tigecycline. (MIC-susceptibility limits determined by EUCAST). Isolates with an MIC level 8 mg/L were considered as resistant to linezolid. Results: All the Staphylococcus cohnii ssp. urealiticum clinical isolates were resistant to linezolid with an MIC level 24 mg/L. The tigecycline was found absolute active to all the examined linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. The inhibition diameter zones for tigecycline were found of 22 mm and the tigecycline-MIC levels of 0.125 mg/L. Conclusion: Tigecycline is absolute active to all linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. This new glycycline is consisted an alternative option for treatment of infections caused by these isolates. Clinical laboratories should be routinely testing tigecycline susceptibility in all clinically significant Staphylococci; so that any changes to the current status may be detected as soon as possible.
P2039 Evaluation of tigecycline in vitro activity against panresistant Klebsiella pneumoniae clinical isolates A. Stylianakis, A. Koutsoukou, S. Tsiplakou, V. Garavella, M. Taxtatzis, I. Merianos (Athens, GR) Objectives: The purpose of our study was to evaluate the in vitro activity of tigecycline against panresistant Klebsiella pneumoniae clinical isolates. Methods: We examined 68 non duplicated panresistant Klebsiella pneumoniae isolates recovered from blood cultures, bronchoalveolar excretions and pus and urine samples derived from ICU-patients of our hospital during a one year-time period. The identification of the isolates and the susceptibility testing were performed by the automated VITEK 2 system (boiM´erieux, France). The susceptibility testing for tigecycline was performed by Kirby-Bauer disk diffusion method and done by direct colony suspension according to CLSI guidelines. Paper disks containing tigecycline at 15 mg per disk were used (Becton-Dickinson, USA). The determination of tigecycline-MIC values was performed by E-test strips according to the manufacturer’s guidelines (AB-Biodisk, Sweden). Isolates with an inhibition zone diameter of 19 mm and with an MIC level 1 mg/L were considered as susceptible to tigecycline (MIC-susceptibility limits determined by EUCAST). Results: All the Klebsiella pneumoniae clinical isolates were resistant to aminoglycosides, b-lactams, carbapenems, monobactames, furanes, cinolones and colistin. The tigecycline was found absolute active to all the examined isolates. The inhibition diameter zones were found of 21 mm and the MIC levels of 0.5 mg/L Conclusion: Tigecycline is absolute active to panresistant Klebsiella pneumoniae isolates and holds great promise as a therapeutic agent to combat or limit desperate infections caused by these panresistant isolates.
S587
Conclusion: MICs of TIG obtained by both methods (A and B) appeared identical or very similar. The susceptibility zone diameter breakpoint recommended in France by using the 15 mg TIG disks could be 22 mm for all species. However, for Enterobacteriaceae, except Proteus, Morganella and Providencia showing a poor susceptibility to TIG, MICs should be determined on isolates with zone diameter <22 mm.
P2037 In vitro antibacterial activity of tigecycline against anaerobic hospital isolates; comparison of two methods in France: a multicentre study L. Dubreuil, L. Calvet, V. Jarlier, J. Cavallo, M. Chomarat, H. Drugeon, M. Kitzis, C. Soussy, C. Lascols, M. Roussel-Delvallez, C. Muller-Serieys, R. Leclercq, J. Rolain, A. Dubanchet (Lille, Paris, Saint-Mand´e, Lyon, Nantes, Cr´eteil, Caen, Marseilles, FR) Objectives: The aim of the study was to compare the MICs of tigecycline (TIG) by agar dilution (A) using the Clinical Laboratory Standards Institute (CLSI) M11 A6 method and a disk-diffusion test using the Comit´e de l’Antibiogramme de la Soci´ete Fran¸caise de Microbiologie (CA-SFM) method and to propose zone diameter breakpoints for clinical categorisation in France. Methods: MICs of TIG were determined by the reference agar method M11A6 against 230 strains collected in 10 university hospitals in France in 2006. Antibiograms were performed with 15 mg disks, according to the CA-SFM method on Brucella blood agar. An internal quality control was carried out with B. fragilis ATCC25285, B. thetaiotaomicron ATCC 29741 and Eggerthella lenta ATCC 43055. Results: Results for TIG are shown in the table. By disk-diffusion test the range for the inhibition zones were 28−41 mm for GPAC, 21−37mm for clostridia (with exception of C. perfringens inhibition zone 14−35 mm), and 11−40 mm for the B. fragilis group. Considering the 4 mg/L CLSI breakpoint, the susceptibility zone diameter breakpoint recommended in France by using the 15 mg TIG disks could be ? 21 mm for all species except C. perfringens. MIC should be determined on isolates with zone size diameter <20 mm.
Bacterial species
Bacteroides fragilis (84) Bacteroides thetaiotaomicron (14) Other Bacteroides (19) All Bacteroides of the fragilis group (117) Prevotella spp. (4) C. perfringens (48) C. difficile (18) Other clostridia (6) Finegoldia magna (13) Micromonas micros (10) Other GPAC: Gram-positive cocci (14) All Gram-positive anaerobes (109) All anaerobes (230)
MIC (mg/L) Range
MIC50 MIC90
0.06−16 0.06−16 0.06−2 0.06−16 0.06–0.125 0.06−2 0.06–0.25 0.06−0.5 0.06−0.5 0.06−0.5 0.06−0.5 0.06−2 0.06−16
0.5 2 0.25 0.5 ND 0.5 0.125 0.5 0.125 0.125 0.125 0.125 0.25
2 16 1 2 ND 1 0.25 0.5 0.25 0.25 0.25 1 2
Conclusion: Categorisation by disk-diffusion test remains difficult for anaerobes. Among the B. fragilis group, resistance to metronidazole or imipenem could not be detected, but decreased susceptibility to metronidazole (4.3%) was observed. TIG 4 mg/L inhibited 111/117 strains of the B. fragilis group meanwhile TIG 2 mg/L was able to inhibit all Gram-positive anaerobes. Thus, at a concentration of 4 mg/L, TIG inhibited 97.3% of the investigated strains.
P2038 In vitro activity of tigecycline against linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates A. Stylianakis, A. Koutsoukou, S. Tsiplakou, S. Sardiniari, A. Vourtsi, I. Merianos (Athens, GR) Objectives: The purpose of our study was to evaluate the in vitro activity of tigecycline against linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. Methods: We examined 18 non duplicated linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. These isolates were recovered from blood cultures of ICU patients of our hospital during a 12 months time period. The identification and the susceptibility testing of the isolates were performed by the automated VITEK 2 system (boiM´erieux, France). The susceptibility testing for tigecycline was performed by Kirby-Bauer disk diffusion method and done by direct colony suspension according to CLSI guidelines. Paper disks containing tigecycline at 15 mg per disk were used (Becton-Dickinson, USA). The determination of tigecycline and linezolid MIC values was performed by using E-test strips according to the manufacturer’s guidelines (ABBiodisk, Sweden). Isolates with an inhibition zone diameter of 19 mm and with an MIC level 0.5 mg/L were considered as susceptible to tigecycline. (MIC-susceptibility limits determined by EUCAST). Isolates with an MIC level 8 mg/L were considered as resistant to linezolid. Results: All the Staphylococcus cohnii ssp. urealiticum clinical isolates were resistant to linezolid with an MIC level 24 mg/L. The tigecycline was found absolute active to all the examined linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. The inhibition diameter zones for tigecycline were found of 22 mm and the tigecycline-MIC levels of 0.125 mg/L. Conclusion: Tigecycline is absolute active to all linezolid-resistant Staphylococcus cohnii ssp. urealiticum clinical isolates. This new glycycline is consisted an alternative option for treatment of infections caused by these isolates. Clinical laboratories should be routinely testing tigecycline susceptibility in all clinically significant Staphylococci; so that any changes to the current status may be detected as soon as possible.
P2039 Evaluation of tigecycline in vitro activity against panresistant Klebsiella pneumoniae clinical isolates A. Stylianakis, A. Koutsoukou, S. Tsiplakou, V. Garavella, M. Taxtatzis, I. Merianos (Athens, GR) Objectives: The purpose of our study was to evaluate the in vitro activity of tigecycline against panresistant Klebsiella pneumoniae clinical isolates. Methods: We examined 68 non duplicated panresistant Klebsiella pneumoniae isolates recovered from blood cultures, bronchoalveolar excretions and pus and urine samples derived from ICU-patients of our hospital during a one year-time period. The identification of the isolates and the susceptibility testing were performed by the automated VITEK 2 system (boiM´erieux, France). The susceptibility testing for tigecycline was performed by Kirby-Bauer disk diffusion method and done by direct colony suspension according to CLSI guidelines. Paper disks containing tigecycline at 15 mg per disk were used (Becton-Dickinson, USA). The determination of tigecycline-MIC values was performed by E-test strips according to the manufacturer’s guidelines (AB-Biodisk, Sweden). Isolates with an inhibition zone diameter of 19 mm and with an MIC level 1 mg/L were considered as susceptible to tigecycline (MIC-susceptibility limits determined by EUCAST). Results: All the Klebsiella pneumoniae clinical isolates were resistant to aminoglycosides, b-lactams, carbapenems, monobactames, furanes, cinolones and colistin. The tigecycline was found absolute active to all the examined isolates. The inhibition diameter zones were found of 21 mm and the MIC levels of 0.5 mg/L Conclusion: Tigecycline is absolute active to panresistant Klebsiella pneumoniae isolates and holds great promise as a therapeutic agent to combat or limit desperate infections caused by these panresistant isolates.