Open AccessRegional Profiling for Determination of Genotype Diversity of Mastitis-Specific Staphylococcus aureus Lineage in Canada by Use of Clumping Factor A, Pulsed-Field Gel Electrophoresis, and spa Typing
Author(s) -
Kamaleldin B. Said,
Johanne Ismaïl,
Jennifer Campbell,
Michael R. Mulvey,
Anne–Marie Bourgault,
Serge Messier,
Xin Zhao
Publication year - 2010
Publication title -
journal of clinical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.349
H-Index - 255
eISSN - 1070-633X
pISSN - 0095-1137
DOI - 10.1128/jcm.01768-09
Subject(s) - genotype , typing , biology , pulsed field gel electrophoresis , mastitis , staphylococcus aureus , microbiology and biotechnology , dna profiling , gel electrophoresis , genetics , bacteria , gene , dna
One of the major concerns in global public health and the dairy industry is the emergence of host-specific virulentStaphylococcus aureus strains. The high degree of stability of the species genome renders detection of genetic microvariations difficult. Thus, approaches for the rapid tracking of specialized lineages are urgently needed. We used clumping factor A (clfA ) to profile 87 bovine mastitis isolates from four regions in Canada and compared the results to those obtained by pulsed-field gel electrophoresis (PFGE) andspa typing. Twenty-five pulsotypes were obtained by PFGE with an index of discrimination of 0.91. These were assigned to six PFGE lineage groups A to F and sevenspa types, including two novel ones. Group A had 48.3% of the isolates and group D had 43.7% of the isolates, while only 8% of the isolates were variable. The results of antimicrobial susceptibility testing indicated that all isolates were sensitive to methicillin and the non-beta-lactam antibiotics, while three isolates were resistant to penicillin and one isolate was resistant to tetracycline. All isolates had theclfA gene and belonged to 20clfA repeat types with an index of discrimination of 0.90. The dominantclfA types, types X, Q, C, and Z, formed 82% and 43% of PFGE groups A and D, respectively, and had copy numbers that varied only within a narrow range of between 46 and 52 copies, implying clonal selection. The rest were variable and region specific. Furthermore, the dominant groups contained subpopulations in different regions across Canada. Sequence information confirmed the relatedness obtained by the use ofclfA repeat copy numbers and other methods and further revealed the occurrence of full-repeat deletions and conserved host-specific codon-triplet position biases at 18-bp units. Thus, concordant with the results of PFGE andspa typing,clfA typing proved useful for revealing the clonal nature of the mastitis isolate lineage and for the rapid profiling of subpopulations with comparable discriminatory powers.