Properties Of Strains of Staphylococcus Aureus in the 94, 96 Complex

Abstract

PHAGES 94 and 96 were introduced into the basic set of phages for typing strains of Staphylococcus aureus after they were shown to be useful in identifying otherwise untypable strains of this organism (Subcommittee on phage-typing of staphylococci, 1975). Phage 94, of serological group A, was isolated in the United States in 1971 (Blouse et al., 1973), and phage 96, a serological group-B phage, in New Zealand by Mrs J. Markham about 1 year later. Although the phages were isolated at different times in different parts of the world and are serologically distinct, they tend to have a rather similar range of lytic activity, and staphylococci that are sensitive to these phages are usually resistant to other basic-set phages. Such strains account for between 9 and 10% of all isolates typed at the Staphylococcus Reference Laboratory, Colindale, at present. We have examined a number of them and find that most have, as reported here, some rather distinctive properties. This suggests that they form a homogeneous group of strains with a possible common origin. MATERIALS AND METHODS Strains of Staphylococcus aureus.Over 200 strains of staphylococci of the 94,96 complex were examined. They included the propagating strains (PS) for the basic-set typing phages 94 and 96 and for phages 14,15,16 and 17. The remainder were strains sent to this laboratory for routine phage typing and represented isolates collected during 1973 to 1975 from 40 different hospitals. All were lysed by phage 94 or phage 96 or by both, and were resistant to lysis by other basic-set phages. Strains used as indicators of lysogenicity were the PS for the 22 basic-set phages and three additional " polyvalent " strains (nos. 1030, 18042 and W57) which are sensitive to most staphylococcal phages.Phage typing was performed according to Blair and Williams (1961). In addition to the 23 phages in the current basic set, five phages showing variable activity against strains susceptible to phages 94 and 96 were tested against a selection of strains. These were phage 47A (no. NCTC8407), which was included in the basic set until the early 1950's, and four phages-nos. 14, 15, 16 and 17-isolated in the Netherlands and kindly supplied by Dr N. van Leeuwen.Tests for lysogenicity. Three-hour cultures in nutrient broth (Oxoid no. 2) were exposed to 0.5 pg of mitomycin C per ml for 30 min. at 37°C. The cultures were then centrifuged, the supernates discarded, and the cells resuspended in the original volume of nutrient broth. After a further 2 h at 37"C, the cultures were centrifuged and the supernates spotted on to nutrient-agar plates which had been flooded with broth cultures of indicator strains.Mutagen treatment. Two mutagens were used-ethyl methane sulphonate (EMS) and N-methyl-N'-nitroso-N-nitroguanidine (NG).

Enterotoxin production by Staphylococcus aureus isolates from cases of septicaemia and from healthy carriers

“…The phage-group I1 septicaemia isolates, apart from a single strain, were non-enterotoxigenic, as found by Bergdoll (1985). Asheshov et al (1977) reported that SEB was produced by > 50% of phage-group V isolates, which also did not produce any other enterotoxin. In this report, 66.6% of the phage-group V septicaemia strains produced SEB only (table I).…”

Clonal study of enterotoxin-B producing strains ofStaphylococcus aureus

“…Responsible mainly for food poisoning, it has also been associated with toxic shock [4][5][6]. The properties of SEB-producing strains (SEB+) are well documented; Asheshov and co-workers [7] demonstrated that the strains in the 94/96 phage complex were very often SEB+; Melconian and colleagues [8] observed that these strains were lysed mainly by phages of groups II and V; and Dornbusch and Hallander [9] have demonstrated a relationship between oxacillin resistance and toxin production. Recently, Lee and colleagues [10] have shown that TS-associated strains produced either TSST-1, enterotoxin B or, exceptionally, both; they have also shown that SEB+ strains belonged to the same zymotype, suggesting a clonal origin.…”

Enterotoxins and toxic-shock syndrome toxin-1 in non-enteric staphylococcal disease

“…Hallander and Laurell [6] found an excess of SEB producing strains in post mortem material. Schlievert [7] showed that SEB could be related to nonmenstrual toxic shock syndrome and we demonstrated that Group V strains could be the source of this toxin [8,9]. Recently, German workers confirmed that the SEB producers in post-mortem specimens type with group V [10].…”