DEVELOPMENT OF RAPID ANTIGEN DETECTION TEST FOR METHICILLIN RESISTANT Staphylococcus aureus INFECTION

Abstract

Methicillin resistant Staphylococcus aureus (MRSA) detection is a challenge to any clinical microbiology laboratory and demands implementation of strict protocols for active screening. This study aims to determine the validity of rapid immunochromotographic (ICT) test for detection compared with the gold standard method. Duplicate swabs were collected from nasal or ear. First swab used for conventional culture and Cefoxitin disk sensitivity. From each culture positive, pure colony were obtained, DNA extracted and conventional polymerase chain reaction for mecA detection were done. The second swab was processed for lateral flow test that constructed in Department of Microbiology laboratory/College of Medicine/ Al-Nahrain University. Monoclonal capture anti-PBP2a (test line) and goat anti-mouse IgG antibodies (control line) were applied on each nitrocellulose membrane. Gold-in-a-BoxTM conjugation kit (40nm. 15OD) conjugated monoclonal anti- PBP2a were adsorbed in conjugate pad. Then assembled in the test cassette. Serially diluted Methicillin resistance S. aureus (1-108cfu/ml) and Methicillin sensitive S. aureus also used in concentration 108 (cfu/ml). Bacterial cells treated with lysozyme for 30 minutes and distilled water were loaded on a strip and visually evaluated after 30 min. The minimum detection limit of the immunochromatography test was 103cfu/ml. Furthermore, based on comparison of 82 culture positive of different clinical swabs, the specificity and sensitivity of this assay were 100% and 97.1% respectively. While, in comparison with mecA PCR detection the specificity and sensitivity of this assay were 100% and 93.03% respectively. However, the procedure used in this study was less complicated and gives the results within 1hour. This study recommends using of Rapid pbp2a as a new tool for the detection of MRSA directly from clinical samples.