[Restriction fragment length polymorphism of coagulase gene of methicillin-resistant Staphylococcus aureus can be used as an epidemiological marker]

Coagulase-negative variants of methicillin-resistant Staphylococcus aureus subsp. aureus strains isolated from hospital specimens

At the Department of Clinical Bacteriology of Medical University of Warsaw, S. aureus strains displaying negative reactions in the coagulase tube-test were isolated with a relatively high frequency from clinical specimens. As many as seventeen of such strains all from different patients were isolated during 1994 among MRSA strains. Despite coagulase negativity all strains were positive in tests for clumping factor (CF), protein A and thermonuclease. Biochemical characteristics, phage patterns and antibiotic resistance characteristics of these strains were tested. Most of the coagulase-negative strains possessed a heterogenous type of methicillin resistance. Apart from methicillin most of them were resistant to many other antimicrobials. All were resistant to gentamicin, tetracyclines and macrolide-lincosamide-streptogramine B. An occurrence of coagulase-negative S. aureus strains may lead to problems in their identification and the necessity of an application of other methods like CF, protein A or biochemical reactions.

The genome of Staphylococcus aureus: a review

The genome of Staphylococcus aureus consists of a single circular chromosome (2.7-2.8 mbp) plus an assortment of extrachromosomal accessory genetic elements: conjugative and nonconjugative plasmids, mobile elements (IS, Tn, Hi), prophages and other variable elements. Plasmids (1-60 kbp) are classified into 4 classes and there are 15 known incompatibility groups. Mobile elements of the genome (0.8-18 kbp) appear in the chromosome or in plasmids of classes II and III. Prophages (45-60 kbp) are integrated in the bacterial chromosome, and they are UV- or mitomycin-inducible. Temperate bacteriophages of S. aureus are members of the Siphoviridae and the serological groups A, B and F occur most frequently. In the paper presented, the characteristics of chromosome, plasmids, transposons and other genetic elements of S. aureus genome are given and an alphabetical list of known genes of this species is included.