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.
Four different solvente viz., acetone, diethylether, methanol and ethanol have been used to obtain crude extracts from S. johnstonü and the efficiency of the solvente is tested using gram-positive and gram-negative bacteria. The diethyl-ether extract exhibited Optimum antibacterial activity äs compared with the rest. Six differently preserved samples viz., frozen, shade dried, sun dried, oven dried, fresh and semi-fresh, were extracted with diethyl-ether and the extracts tested against gram-positive and gram-negative bacteria. Shade dried samples exhibited Optimum activity when compared with other seaweed samples.In another experiment, lipids from samples preserved äs listed above were extracted into Chloroform: methanol (2: l v/v) and the extract divided into two fractions. These two fractions were tested for their antibacterial acitivity against gram-positive and gram-negative bacteria. The fraction from a shade dried sample obtained using diethyl-ether äs the solvent exhibited a higher antimicrobial activity than the fraction extracted by solvent benzene.Botanica Marina / Vol. XXIX / 1986 / Fase. 6 Copyright © 1986 Walter de Gruyter · Berlin · New York and suitable solvent and to determine which type of preserved algal sample is best for achieving Optimum antibacterial activity against gram-positive and gramnegative test-bacteria. Material and MethodsThe seaweed samples were collected during low water of spring tides. Only healthy, fully grown plants still submerged under water during low tides were collected. The seaweed samples were cleaned with many changes of fresh seawater to remove epiphytes, Shells etc. attached to the algae and then dried under shade. The dried samples were brought to the laboratory and thoroughly washed first with sterile seawater Brought to you by | University of Arizona Authenticated Download Date | 6/1/15 6:18 AM
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