Emergence of vancomycin intermediate resistance in community-acquired methicillin-resistant Staphylococcus aureus

Abstract number: R2371

Tzampaz E., Protonotariou E., Antachopoulos C., Meletis G., Roilides E., Sofianou D.

Objectives: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is well recognised as an important pathogen that causes predominantly skin and soft-tissue infections and infrequently life-threatening infections, mostly among children. Vancomycin (VA) is the drug of choice for the treatment of these infections. We describe the isolation of a CA-MRSA with intermediate resistance to VA from a 4-year old girl admitted to the hospital with sepsis and severe multifocal infections including pericarditis, pleural effusions, septic arthritis and osteomyelitis. She was initially treated with combination of VA and clindamycin and had a long complicated course.

Methods: Three CA-MRSA strains were isolated from blood, wound and pericardial pus. Bacterial identification and initial susceptibility testing was performed with the VITEK2 automated system. MICs of vancomycin, teicoplanin, erythromycin, clindamycin, daptomycin, linezolid and tigecycline were determined by E-test. All isolates were subjected to PCR in order to identify the presence of Staphylococcal Cassette Chromosome type IV (SCCmecIV), Panton-Valentine leukocidin (PVL) and Van A and B genes.

Results: Susceptibility testing results demonstrated that two isolates had intermediate susceptibility to VA (MIC, 3 mg/L). All three were susceptible to erythromycin, clindamycin (both MIC, leqslant R: less-than-or-eq, slant0.25 mg/L), teicoplanin (MIC, 1–1.5 mg/L), daptomycin (MIC, 0.19–0.25 mg/L), linezolid (MIC, 2 mg/L) and tigecycline (MIC, 0.25–0.38 mg/L). According to the updated CLSI and EUCAST interpretive criteria the isolates recovered from blood and wound fluid are considered as VISA. All isolates carried SCCmecIV and PVL genes. No isolate was positive for Van genes.

Conclusions: The emergence of VISA in CA-MRSA is of great concern. These isolates are not easily detected with routine laboratory antimicrobial testing. As outcome of severe staphylococcal infections depends on the rapid and appropriate therapy, investigation for the presence of VISA in cases of CA-MRSA infections is warranted.

Session Details

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