Identification of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) causing hospital-acquired infections in Suez Canal University Hospitals, Egypt by detection of its major virulence determinants

Abstract

Background: Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is emerging in hospitals, worldwide.

Method: In Suez Canal University Hospitals (SCUH), we documented CA-MRSA causing hospital acquired- (HA-) sepsis, by polymerase chain reaction (PCR) amplification of CA-MRSA major virulence determinant genes, namely: Panton-Valentine leukocidin "pvl", accessory regulator "agr" I and III, and staphylococcal cassette chromosome mec "SCCmec" genes IV and V. Antibiograms were determined by disk diffusion and minimum inhibitory concentration (MIC).

Results: Methicillin resistant staphylococcus aureus was detected in 90 hospital acquired infections (HAIs), including bacteremia, pneumonia, osteomyelitis, soft tissue infections, and meningitis. Pvl gene, characterizing CA-MRSA, was detected in 24/90 MRSA strains (26.7%). Pvl+ve strains were subtyped into SCCmec gene type II (8.3%), type IV (75%), type V (8.3%), and 8.3% were non-typeable. They showed only agr group I (62.5%), and III (37.5%). Co-trimoxazole resistance was detected in 41.6% of CA-MRSA. Only 12.5% of CA-MRSA strains were susceptible to all non-beta-lactam drugs. There was no statistical correlation between SCCmec or agr groups, and co-trimoxazole resistance in CA-MRSA; nor between SCCmec types and agr groups.

Conclusion: Community aquired-MRSA is emerging in all wards of SCU hospitals, causing HAI, mostly soft tissue infections. The classical antibiogram of CA-MRSA is no longer prevailing. Diagnosis of CA-MRSA should rely upon detection of pvl gene, rather that clinical and antibiogram-profiles. The name "CA-MRSA" is no longer satisfactory to describe such strains in hospital settings; instead, Pvl+ve MRSA is more accurate and reliable term to use.