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In vitro susceptibility and pathogen prevalence data in complicated skin and skin-structure infections: results of the RELIEF study

Abstract number: R2288

Gyssens I.C., Dryden M., Kujath P., Nathwani D., Schaper N., Arvis P., Reimnitz P., Alder J., Hampel B.

Objectives: The choice of antimicrobial therapy in complicated skin and skin structure infections (cSSSIs) is complex due to the potential diversity of the pathogens present. In particular, cSSSIs are characterised by a high prevalence of Staphylococcus aureus, including methicillin (oxacillin [OXA])-resistant S. aureus (MRSA) both in hospital and community settings. Furthermore, in recent years, serious cSSSIs caused by multi-drug resistant pathogens – including non-fermentive Gram-negative bacilli and Enterobacteriaceae – have become more common. This has created the need for additional therapeutic agents such as broad spectrum fluoroquinolones. In the present study, we evaluated the antimicrobial activity of moxifloxacin (MXF) and commonly used antimicrobial agents against recent clinical bacterial isolates collected in the RELIEF study.

Methods: RELIEF was a double-dummy, double-blind, randomised controlled trial conducted from 2007 to 2008 in 15 countries, most in Europe. Acceptable culture specimens included skin biopsy, curettage of the wound base after debridement, tissue or bone biopsy, aspiration of purulent secretions including leading-edge needle aspiration. Clinically significant isolates (n = 1120) were recovered for processing from 603/803 patients in the ITT population who had at least one organism at isolated at baseline. Minimum inhibitory concentrations (MIC) values for MXF and amoxicillin/clavulanic acid (AMC), ceftazidime (CFZ), ceftriaxone (CRO), ertapenem (ERT), gentamicin (GEN), metronidazole (MET), OXA and piperacillin/tazobactam (PIP/TAZ) were determined using validated reference broth microdilution panels. Testing, incubation and MIC interpretation were performed according to CLSI guidelines.

Results: The most frequently isolated pathogens (found in geqslant R: gt-or-equal, slanted20 patients) were S. aureus (416/1120, 37.1%) of which 12% were methicillin resistant, Enterococcus faecalis (135/1120, 12.1%), E. coli (126/1120, 11.3%), Streptococcus pyogenes (73/1120, 6.5%), Bacteroides fragilis (50/1120, 4.5%), Streptococcus agalactiae (50/1120, 4.4%), Streptococcus equisimilis (31/1120, 2.8%), Acinetobacter baumannii (23/1120, 2.1%) and Pseudomonas aeruginosa (21/1120, 1.9%). MICs for the pathogens vs antimicrobial agents are shown in the Table.

Conclusion: MXF demonstrated good in vitro activity against most cSSSI pathogens. MXF MIC values were comparable with those of antimicrobial agents commonly used for the treatment of cSSSIs.

Table: MIC50/MIC90 (mg/L) for pathogens obtained from patients with cSSSIs

OrganismNMXFPIP/TAZAMCOXACROCFZGENERTMET
Gram-positive bacteria
MSSA3680.03/
0.06
1/
2
0.5/
1
0.25/
0.5
4/
4
8/
8
0.5/
1
0.12/
0.25
-
MRSA482/
4
16/
>128
8/
>32
>8/
>8
64/
>64
64/
>64
>32/
>32
2/
>32
-
S. pyogenes730.12/
0.25
leqslant R: less-than-or-eq, slant0.25/
leqslant R: less-than-or-eq, slant0.25
leqslant R: less-than-or-eq, slant0.06/
leqslant R: less-than-or-eq, slant0.06
-leqslant R: less-than-or-eq, slant0.06/
leqslant R: less-than-or-eq, slant0.06
0.12/
0.25
8/
8
leqslant R: less-than-or-eq, slant0.015/
leqslant R: less-than-or-eq, slant0.015
-
S. agalactiae500.12/
0.25
0.5/
0.5
0.12/
0.12
-0.12/
0.12
0.5/
1
32/
32
0.06/
0.06
-
S. equisimilis310.12/
0.25
leqslant R: less-than-or-eq, slant0.25/
leqslant R: less-than-or-eq, slant0.25
leqslant R: less-than-or-eq, slant0.06/
leqslant R: less-than-or-eq, slant0.06
-leqslant R: less-than-or-eq, slant0.06/
leqslant R: less-than-or-eq, slant0.06
0.25/
0.25
8/
>32
0.03/
0.03
-
E. faecalis1350.25/
16
4/
8
1/
1
->64/
>64
>64/
>64
16/
>32
8/
8
-
Gram-negative bacteria
E. coli1260.06/
16
2/
4
4/
16
-leqslant R: less-than-or-eq, slant0.06/
0.12
0.12/
0.25
0.5/
2
leqslant R: less-than-or-eq, slant0.015/
leqslant R: less-than-or-eq, slant0.015
-
  Non-ESBL1190.06/
2
2/
4
4/
16
-leqslant R: less-than-or-eq, slant0.06/
leqslant R: less-than-or-eq, slant0.06
0.12/
0.25
0.5/
2
leqslant R: less-than-or-eq, slant0.015/
leqslant R: less-than-or-eq, slant0.015
-
  ESBL716/
>32
2/
16
8/
16
->64/
>64
1/
16
16/
>32
0.03/
0.06
-
P. aeruginosa218/
>32
16/
>128
>32/
>32
->64/
>64
8/
64
8/
>32
8/
>32
-
A. baumannii232/
8
64/
>128
>32/
>32
->64/
>64
32/
>64
>32/
>32
4/
16
-
Anaerobes
B. fragilis510.5/
2
0.25/
1
------1/
1
- denotes not tested.

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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