Identification and Molecular Characterization of Methicillin Resistant Staphylococcus Aureus Obtained From Raw Dairy Milk and Human Blood

Abstract

Staphylococcus aureus (S. aureus) is a unique microorganism among Staphylococcus spp notoriously recognized globally for its clinical importance in causing clinical or subclinical bovine mastitis in livestock. In humans, it causes food poisoning, toxic shock syndrome, scalded skin disease and bacteraemia as an invasive complication, which may result to osteomyelitis, endocarditis, boils, cellulitis, pneumonia and thrombophlebitis among others. The dissemination of S. aureus and its variant methicillin resistant S. aureus (MRSA) between different animal species has been documented in many developed countries especially in regions of high dairy farming, pointing out livestock associated MRSA (LAMRSA), community affiliated MRSA (CA-MRSA) and hospital affiliated MRSA (HAMRSA) which may freely be transmissible between domesticated and wild animals, poultry and humans. The aims of this study included: isolation and identification of S. aureus from blood of human patients and raw cow milk, determinination of antimicrobial susceptibility (AST) patterns of S. aureus from human blood and raw dairy milk from selected farms in peri-urban Nairobi, to determine and compare resistant phenotypes of S. aureus strains isolated from milk against those isolated from blood of human patients and to determine the various genetic determinants for MRSA strains and therafter undertake sequencing g of resistant genotypes. The study used convenience sampling strategy, in a one off sampling process employing inclusion and exclusion criteria. The samples were collected between November 2016 and October2017. A total of 353 milk samples and 142 human blood samples were collected.........................................................................