Molecular Characteristics of Community-Associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) Isolates from Clinical Specimens in Iraq

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infections have been recognized for decades as hospital acquired MRSA (HA-MRSA). Nowadays, MRSA is also recognized as a worldwide emerging community-associated pathogen. Community associated-MRSA (CA-MRSA) has been shown to be more virulent with a high degree of severity of disease when compared to HA-MRSA.

Objectives: The study was designed to assess the occurrence and the molecular detection of HA-MRSA and CA-MRSA isolates obtained from clinical specimens in Iraq.

Methods: HA-MRSA and CA-MRSA isolates were obtained from clinical specimens in three main hospitals in Hilla city/Iraq during the period, March to June 2011. MRSA isolates obtained primarily from clinical specimens of skin and soft tissue infections (SSTs) were subjected to genetic study. PCR was used for detection of genes responsible for methicillin resistance (mecA, SCCmec type IV) and genes responsible for toxin production (pvl, lukED). Statistical analysis was performed using chi-square (X2) test to assess intergroup significance, inpatients, and outpatients with respect to all genes used in present study.

Results: Out of 301 clinical samples, 24 MRSA isolates were obtained. All these MRSA isolates (100.0%) were mecA gene positive. Twenty three (95%) were found to be carrying SCCmec type IV, 19 (79%) had positive result for pvl toxin gene, and 20 (83%) had lukED toxin gene.

Conclusion: The majority of MRSA isolates belonged to SCCmec IV. pvl and lukED toxin genes are also found in the MRSA isolates among the CA-MRSA isolates