Genotypic and Phenotypic Characterization, Antibiotic Resistance and Virulence Patterns of <i>Staphylococcus aureus</i> Isolated form Goat Mastitis

Abstract

Objective: To determine the phenotypic and genotypic characterization of the virulence and antimicrobial susceptibility of S. aureus.

Design: Descriptive study

Samples: 175 raw goat milk samples

Procedures: A total of 88 S. aureus strains was isolated from goat with mastitis in north-west cost of Egypt. PCR technique was used to  detect genes coding some virulence and antimicrobial properties while phenotypic antimicrobial susceptibility was determined by the  disc diffusion method.

Results: Most S. aureusisolates were resistant to amoxycillin (89.7%), penicillin G (88.5%), and ampicillin (86%) while were less resistant to  other members of β-lactam group as cefoxitin (17.2%) and ceftriaxone (10.3%).The lowest resistant rates were toward fluroquinolone  group members; ciprofloxacin, levofloxacin and ofloxacin in rates 1.2%, 2.3% and 4.5%, respectively. Tetracycline showed the highest level  of phenotypic resistance (34.6%) and prevalence of a tetK gene (39.1%). The virulence factors, spa and coa exhibited prevalence rate  of 6.9% and 8%, respectively with significant relationship between them.

Conclusion and Clinical relevance: The problem of  antimicrobial resistance needs strict measures to limit the indiscriminate use of antibiotics and concerted research efforts to limit the  spread of resistant bacteria, which will negatively affect human health and control of the infectious diseases in both humans and animals.