Haemolysis by urinary Escherichia coli and virulence in mice

Abstract

PLATE XVIIISUMMARY. The influence of haemolysin production on virulence was studied in an experimental mouse model. Urinary strains of Escherichia coli can be divided into three virulence groups by determining their kinetics in the mouse kidney after intravenous injection. Virulent strains of groups I1 and I11 were more often haemolytic than avirulent group-I strains. Haemolytic virulent strains often caused haemoglobinuria in the mice, and killed the mice more rapidly than did non-haemolytic virulent strains. No relationship was found between a-haemolytic activity and virulence in wild-type haemolytic strains. When haemolysin production was reduced or eliminated by treatment with actinomycin-D or rifampicin, six out of seven group-I1 strains tested gave the same results as avirulent group-I strains. However, the kinetics in the mouse kidney of four haemolytic group-I11 strains tested was not changed after reduction or elimination of haemolysin production; only a small decrease in toxicity was observed. It is concluded that haemolysin production by E. coli is a decisive virulence factor in most of the mouse-nephropathogenic group-I1 strains, but not in the virulent group-I11 strains.

Correlation between electrophoretic types B1and B2of carboxylesterase B and host-dependent factors inEscherichia colisepticaemia

“…The type B2 could be considered as a molecular marker of virulence, but it is not known whether esterase type B2 contributes directly or indirectly to the disease process or whether it is only associated with virulence factors. To evaluate this association, we have correlated types B1 and B2 with a-haemolysin and MRHA, which have been well documented as virulence factors (Hagberg et al 1981;Van den Bosch et al 1981;Welch et al 1981; Gadeberg, Orskov & Rhodes, 1983;Hacker et al 1983;Cavalieri, Bohach & Snyder, 1984) and considered to be genotypically linked (Berger et al 1982;Low et al 1984). The proportion of type B1 strains and type B2 strains producing a MRHA were comparable in septicaemia (28 and 68 %, respectively) to those found in an earlier study (30 and 70°%, respectively) (Goullet & Picard, 1986b).…”

“…some 0 and K antigens (Orskov et al 1977; Orskov & Orskov, 1985), resistance to serum bactericidal activity (Taylor, 1983;Cross et al 1986), virulence to mice and to chicken embryo (Minshew et al 1978; Van den Bosch, De Graaff & MacLaren, 1979; Bosch, Emody & Ketyi, 1982), aerobactin production (Carbonetti et al 1986), a-haemolysin production (Van den Bosch et al 1981;Welch et al 1981;Cavalieri, Bohach & Snyder, 1984) and mannose resistant haemagglutinin (Evans et al 1980;Hagberg et al 1981;Vaisanen et al 1981). However, these infections not only depend on the intrinsic properties of the strains but also on various hostdependent factors, such as susceptibility linked to an underlying disease (Singer, * Author for reprints.…”

“…The proportion of isolates having type B2 was found to be significantly higher in extra-intestinal invasive strains (40 %) than in commensal intestinal strains (7 %) (Goullet & Picard, 1986b). Moreover, the B2 strains were characterized by frequent production of x-haemolysin and a mannose-resistant haemagglutinin (Goullet & Picard, 1986b) which are believed to be the main virulence factors of invasive bacterial strains (Hagberg et al 1981; Van den Bosch et al 1981;Welch et al 1981; Gadeberg, Orskov & Rhodes, 1983;Hacker et al 1983;Cavalieri, Bohach & Snyder, 1984 (Kreger et al 1980 (Kreger et al 1980) recording rapidly fatal (leukaemia) and ultimately fatal diseases (i.e. cancer, cirrhosis, severe diabetes).…”

Escherichia coliin extra-intestinal infections

“…Em6dy et al (1980) could not demonstrate a substantial difference between cultures producing haemolysin and their non-haemolytic derivatives in mice, and van den Bosch et al (1981) also reported that haemolysin was not an important virulence factor in the extremely virulent group III strains which had a more general virulence for mice.…”

“…However, strains of some 0: K: H serotypes within these 0 groups are more often haemolytic than others (Vahlne, 1945;Sj6stedt, 1946). Van den Bosch et al (1981) studied the influence on virulence of haemolysin production in the experimental mouse model mentioned above, which involves intravenous injection of the bacteria (van den Bosch, de Graaf & MacLaren, 1979). They concluded that haemolysin production was a decisive virulence factor in most of the mouse nephropathogenic strains, called group II strains, since 6 out of 7 strains became avirulent after elimination of the ability to produce haemolysin.…”