A study of 435 strains of Staphylococcus pyogenes with reference to factors which may contribute to pathogenicity

Abstract

IN an orthopaedic hospital there is a range of staphylococcal infections varying in site and severity, some remaining localised in the skin, others entering the blood stream and setting up abscesses in bone and elsewhere. This study was undertaken to find out whether strains which cause the more severe infections in man, particularly those MATERIALS AND NETHODS Strains were originally selected by the slide method of Cadness-Graves et al. (1943), but all were subeequently tested on plttsms-ww plates. Human plasme from blood rejected by the blood bank wa8 mixed Coagduae teekr. J . PATE. BACL-VOL. Ispm (1954) 431 43% C. H. LACK AND D . Q. WAILLING Spertruin with nutrient agar in a concentration of 12-15 per cent.(v/v) of plasma a t a temperature of 46" C. The mixture was poured into Petri dishes and spotinoculated. Coagulaae production was indicated by the development of opacity around spots after over-night incubation. All slide-positive strains were also plate-positive. One hundred of these strains were ah0 tested by Fisk's tube method (Fisk, 1940) and found t o be tube-positive. Fibrinolysin tests. A human plasma-agar mixture similar to that deeclribed above wm heated at 56" C. for 20 minutes before pouring. This produced an opaque medium and fibrinolysh was judged by the zone of clearing around colonies after 48 hours' incubation (Christie and Wilson, 1941). Separation of fibrinolysis by plmmin from that by protease was made by incorporating soya-bean trypsin inhibitor in the medium. This inhibited fibrinolysis by p h r n i n but not by staphylococcal protease.

Studies of Staphylococcal Infections. I. Virulence of Staphylococci and Characteristics of Infections in Embryonated Eggs *

“…In addition, strains of staphylococci, lethal to embryonated eggs, have been studied which fail to produce a-hemolysin either in vivo or in vitro (31). A similar situation is found in human infections where a-hemolysin, although produced by most staphylococci isolated from human infections, is not a prerequisite for human pathogenicity (42,43). Other exotoxins may be equally or more important than a-hemolysin in this experimental system, and attempts are in progress to delineate their role and the exact cause of death of the embryo.…”

Lysogenic Conversion of Staphylococci to Loss of -Toxin

“…Kinase was demonstrated by the production of a clear zone on nutrient agar plates containing heated (20 min., 56') rabbit plasma (Lack & Wailling 1954). Soya bean trypsin inhibitor did not decrease the zone.…”

The Clinical Evaluation of Staphylococcal Anti-Alpha Haemolysin Titres in Patients' Sera

“…They all produced hyaluronidase, although it has been shown that virulent strains may not produce hyaluronidase (Schwabacher, Cunliffe, Williams, and Harper, 1945). Lack (1956) has suggested that hyaluronidase may not act as a " spreading factor " but, by depolymerizing hyaluronic acid in connective tissue, it is removing a potential inhibitor. All the strains produced a haemolysin.…”