title: Differentiation of Staphylococcus aureus and Staphylococcus epidermidis by PCR for the fibrinogen binding protein gene.
abstract: Mastitis is one of the most common and burdensome diseases afflicting dairy animals. Among other causes of mastitis, staphylococci are frequently associated with clinical and subclinical mastitis. Although Staphylococcus aureus is the predominant species involved, Staphylococcus epidermidis and other coagulase-negative staphylococci are increasingly being isolated from cases of bovine mastitis. Although Staph. aureus and Staph. epidermidis can be easily differentiated based on their biochemical properties, such phenotypic identification is time consuming and laborious. This study aimed to rapidly identify Staph. aureus and Staph. epidermidis. Accordingly, a multiplex PCR was developed and we found that a single gene encoding the adhesin fibrinogen binding protein could be used to identify and differentiate the two species. Consequently, a multiplex reaction combining a triplex PCR for Staph. aureus and a duplex PCR for Staph. epidermidis was standardized, first using bacterial cultures and then with pasteurized milk spiked with live organisms or DNA extracted from the organisms. The test could specifically detect Staph. aureus and Staph. epidermidis even in the presence of a dozen other organisms. The limit of detection for detecting Staph. aureus and Staph. epidermidis separately was 10 to 100 cfu/mL for simplex PCR and 10(4)cfu/mL for multiplex PCR. Conversely, the limit was 10(6)cfu/mL by multiplex PCR for simultaneous detection of both the organisms when spiked into culture medium or pasteurized milk. Overnight enrichment enhanced the assay sensitivity 100-fold. The assay had a high diagnostic sensitivity and specificity. The application of the test was verified on 602 field isolates of staphylococci that had been characterized earlier by phenotypic methods. Importantly, 25 coagulase-negative isolates were identified as Staph. aureus by the multiplex PCR. The test could be adapted for use in clinical diagnostic laboratories.
authors.affiliation: Ella Foundation, Genome Valley, Turkapally, Shameerpet Mandal, Hyderabad 500078, India.
authors.forename: R
authors.initials: R
authors.lastname: Sunagar
authors.forename: S N
authors.initials: SN
authors.lastname: Deore
authors.forename: P V
authors.initials: PV
authors.lastname: Deshpande
authors.forename: A
authors.initials: A
authors.lastname: Rizwan
authors.forename: A D
authors.initials: AD
authors.lastname: Sannejal
authors.forename: S
authors.initials: S
authors.lastname: Sundareshan
authors.forename: D B
authors.initials: DB
authors.lastname: Rawool
authors.forename: S B
authors.initials: SB
authors.lastname: Barbuddhe
authors.forename: M K
authors.initials: MK
authors.lastname: Jhala
authors.forename: A S
authors.initials: AS
authors.lastname: Bannalikar
authors.forename: D M
authors.initials: DM
authors.lastname: Mugalikar
authors.forename: V J
authors.initials: VJ
authors.lastname: Kumari
authors.forename: K
authors.initials: K
authors.lastname: Dhanalakshmi
authors.forename: Y N
authors.initials: YN
authors.lastname: Reddy
authors.forename: P P
authors.initials: PP
authors.lastname: Rao
authors.forename: C
authors.initials: C
authors.lastname: Babra
authors.forename: J G
authors.initials: JG
authors.lastname: Tiwari
authors.forename: T K
authors.initials: TK
authors.lastname: Mukkur
authors.forename: P
authors.initials: P
authors.lastname: Costantino
authors.forename: J D
authors.initials: JD
authors.lastname: Wetherall
authors.forename: S
authors.initials: S
authors.lastname: Isloor
authors.forename: N R
authors.initials: NR
authors.lastname: Hegde
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D002417:Cattle; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics*; D008414:Mastitis, Bovine / Q000175:diagnosis / Q000382:microbiology; D008892:Milk / Q000382:microbiology; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary; D013211:Staphylococcus aureus / Q000235:genetics*; D013212:Staphylococcus epidermidis / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C089677:Fib protein, Staphylococcus aureus