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Resistance pattern of Staphylococcus aureus clinical isolates from children

Abstract number: p804

Kyratsa  A., Kontekaki  E., Charalambaki  N., Zambou  A., Trikka-Graphakos  E.

Staphylococcus aureus is one of the three most common causes of nosocomial infections, while resistance to antimicrobials is gradually rising.

Objectives: 

To determine antibiotic resistance of S. aureus clinical isolates from children.

Methods: 

We studied retrospectively 124 strains of S. aureus isolated during the last 5 years (2000–2004). Twenty-nine strains were isolated from skin lesions, 25 wounds, 15 eye swabs, 14 ear swabs, 13 nose swabs, 16 blood cultures, 7 umbilical swab and 5 urine specimens. Processing and follow-up was based on conventional methods and identification was performed by Api-Staph (Biomerieux). Resistance of staphylococci was tested by Kirby–Bauer method and MICs to 10 antibiotics were determined by the agar dilution method, according to NCCLS guidelines. Detection of inducible resistance to clindamycin was tested with erythromycin-clindamycin 'D-zone' test. Moreover resistance to methicillin was tested with the following methods: (1) incorporation of oxacillin (6 mg/ml) in Muller–Hinton agar enriched with 4% Nacl, (2) Etest method (AB Biodisk,Solna,Sweden), (3) estimation of zone diameter around cefoxitin disc (30ìg) and (4) agglutination with monoclonal antibody against PBP2a protein (Biomerieux).

Results: 

Resistance of Staphylococcus aureus to methicillin (MRSA) with all methods was 12.7%. Resistance rates to antimicrobials was as follow: penicillin (87%), tetracycline (24.4%), erythromycin (10.4%), clindamycin (5.8%), fucidic acid (6.9%) and gentamycin (1.1%). Inducible resistance to clindamycin was detected in 5.8%. The most common resistance phenotype was oxacillin-tetracycline-fucidic acid. All specimens were sensitive to rifampicin, chloramphenicol, glycopeptides, streptogramines and oxazolidinones.

Conclusions: 

(1) Continuous increase of MRSA, necessitates the use of a combination of laboratory methods for accurate detection of methicillin resistance. (2) 'D-zone' test is a rapid and reliable method for detection of inducible resistance to clindamycin and can be used for discrimination of strains with genetic potential to develop resistance during treatment.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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