Zafar Hussain

Comparison of community-associated and health care-associated methicillin-resistant Staphylococcus aureus in Canada: results of the CANWARD 2007-2009 study.

This study assessed the demographics, antimicrobial susceptibility, and molecular epidemiology of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and health care-associated MRSA (HA-MRSA) in Canadian hospitals between 2007 and 2009. Among 3589 S. aureus, 889 (24.8%) were MRSA; 224 (25.2%) were CA-MRSA genotypes and 644 (72.4%) were HA-MRSA genotypes. The prevalence of CA-MRSA genotypes increased from 19.5% in 2007 to 31.9% in 2009 (P < .001). CMRSA10/USA300 (73.7%) was the predominant CA-MRSA epidemic type; the most common HA-MRSA epidemic type was CMRSA2/USA100/800 (83.5%). CA-MRSA genotypes carried SCCmec type IVa (98.2%) and were largely agr type I (73.2%). Most HA-MRSA genotypes were SCCmec type II (81.2%) and agr type II (83.4%). Panton-Valentine leukocidin was detected in 201/224 (89.7%) CA-MRSA genotypes and 3/644 (0.5%) HA-MRSA genotypes. An increase in vancomycin minimum inhibitory concentration (MIC) was observed in HA-MRSA genotypes overall, with 1.3% (4/305) of strains in 2007 and 4.6% (7/152) in 2009 exhibiting vancomycin MICs of 2 μg/mL. No MRSA resistance occurred with linezolid, daptomycin, or tigecycline. In conclusion, CA-MRSA genotypes represented 25.2% of all MRSA and continue to increase in prevalence in Canadian hospitals.

Comparison of susceptibility results of anaerobic organisms determined by agar dilution method and Sceptor Anaerobe MIC/ID Micro Broth Dilution Panels.

A commercial broth microdilution system (Sceptor Anaerobe MIC/ID, BBL) for susceptibility testing of anaerobic bacteria was compared to a reference agar dilution system. Of the 172 organisms tested, only 7% failed to grow sufficiently for testing in the Sceptor system. In 1,590 antibiotic/organism combinations, 86.7% of the Sceptor results were identical or within one doubling dilution of the reference system. In 91.9% of the cases, interpretation of the results was same in both systems. Two hundred and twelve MIC values, however, differ by greater than or equal to 2 log2 dilution from the reference system. Due to this reduced correlation in the actual MIC values with the reference results, further studies are warranted before the Sceptor system can be recommended for routine use.