Molecular and phylogenetic study of Staphylococcus aureus isolated from human and cattle of Al-Qadisiyah Governorate, Iraq

Abstract

Aim: This study was designed to detect the prevalence of Staphylococcus aureus, to estimate the frequency of methicillin resistance gene (mecA), femA (specific gene for S. aureus), and lukS gene, and the prevalence of urinary tract infection (UTI) in human and bovine mastitis caused by S. aureus. Materials and Methods: A total of 102 cases of S. aureus were included in this study; 72 specimens were isolated from human with UTIs and 30 specimens were isolated from milk of cattle with acute mastitis. Diagnosis was done by VITEK 2 Compact after subculture and purification. All isolates were examined for the presence of mecA, femA, and lukS (Panton- Valentine leukocidin) using multiplex polymerase chain reaction. Results: Culture and biochemical evaluation of the samples revealed the presence of S. aureus, among which the genes mecA, femA, and lukS were positively detected in 68 (94.4%), 36 (50%), and 20 (27.7%) of S. aureus isolates from methicillin-resistant humans, respectively. In the same manner, the genes mecA, femA, and lukS were positively detected in 27 (90%), 14 (46.7%), and 11 (36.7%) of S. aureus isolates from methicillin-resistant cattle. Sequencing of partial order of femA gene isolated from human isolate and from cattle with mecA isolated from human revealed high sequence identity with the National Center for Biotechnology Information (NCBI)-Basic Local Alignment Search Tool. S. aureus isolates and the phylogenetic analysis showed that there was a significant genetic similarity (0.5 genetic change) between human and animals isolates, and then, the gene sequences were deposited into NCBI-Genbank accession numbers MG696860.1 for mecA and femA from human, MG696861.1 for mecA and femA from cattle, MK474469.1 for mecA and femA gene from human, and MG696862.1 for mecA and femA gene from cattle. Conclusion: The study represents the first report of genetic relationship between S. aureus from humans and cattle of Iraq. Therefore, it is essential to define the role of animals as an important source of the distribution of pathogen related to public health. The continuous monitoring of methicillin susceptibility pattern of S. aureus isolates that have high standards of infections might prevent methicillin-resistant S. aureus transmission in either direction between human and cattle, the risk of dairy milk on humans, or self-direction between the same species.