Biochemical and Molecular Identification of Type V MRSA among Students at a Small Southern University

Abstract

Staphylococcus aureus is a commensal organism of healthy individuals associated with the skin and mucosal membranes. Methicillin-resistant S. aureus (MRSA) has become a serious health concern due to its resistance to antibiotics. There are eight types of MRSA, with type V MRSA having its origins in India; few type V have been reported in the United States. This study was initiated to determine if type V is present in south Texas and to find out if the transmission of this uncommon type amongst students at Texas A&M University-Kingsville is possible. Through biochemical testing, seventy-eight out of 200 domestic students (39) and international students (39) were identified as carriers for S. aureus. Of those 78 students, 19 (25%) were positive for MRSA. Six (32%) of the 19 students were domestic and 13 (68%) were international. Polymerase chain reaction methodology was used to identify one type I, five type IV, and 10 type V MRSA isolates. Four isolates were determined to be “non-typable”. Two (33%) of the six domestic student MRSA isolates and eight (62%) of the 13 international student isolates were determined to be type V MRSA. A Pearson’s Chi-square test found a significant difference between the number of type V strain positive domestic students and international students (X2=4.08, df=1, p=0.043). There was no significant difference between the number of domestic and international students as carriers of S. aureus or MRSA. Additionally, health-care associated MRSA type I was isolated from a campus computer along with two type V community-associated MRSA strains, which suggests that indirect transmission may play a role in the spread of these pathogens. These results indicate that although type V MRSA is considered rare in the United States, it is probably more prevalent than suspected.