Characterization of antimicrobial resistant bacterial pathogens recovered from cases of bovine mastitis with special reference to Staphylococcus aureus

Document Type : Original Article


1 Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62511, Egypt.

2 Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Cairo University, Egypt.

3 Animal Health Research Institute, Beni-Suef Branch, Beni-Suef, Egypt.


In the current study, a total of 20 and 78 milk samples were collected from animals
showed signs of clinical and subclinical mastitis, for isolation and identification of
different causative pathogens in some dairy farms of Beni-Suef Governorate, and
for investigation of in vitro sensitivity. The recovered microorganisms were
Staphylococcus species (n=79; 80.61%), Enterococcus spp. (n=28; 28.57%), CAMP
negative Streptococci, Pseudomonas aeruginosa (n=7; 7.14%), E. coli (n=3; 3.06%)
and Proteus vulgaris (n=1; 1.02%). Antibiogram profile for S. aureus showed that
the most effective drug was vancomycin and the least was penicillin. Trials were
done to detect biofilm production for recovered isolates of S. aureus (n=23) by the
use of a phenotypic method (Congo red agar, CRA) and genotypic methods
through determination of some biofilm related genes using PCR. All recovered S.
aureus isolates were seeded on the CRA media to detect the biofilm forming
ability. It has been found that all tested isolates showed a biofilm forming ability
either strong (13; 56.52%) or intermediate (10; 43.48%). The detection of some
biofilm associated genes (icaA, icaD and bap genes) using polymerase chain
reaction revealed that two (10.53%) isolates out of 19 were negative for all tested
genes, 16 (84.21%) isolates harbored both icaA and icaD gene, while only one
(5.26%) isolate had all tested genes.


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