S U M M A R YAttempts to study quantitatively the phagocytosis of gonococci from urethral pus failed because of the small numbers of organisms and technical difficulties. However, gonococci from chambers implanted subcutaneously in guinea pigs, which were similar to gonococci from urethral pus in their resistance to killing by human serum, were obtained in sufficient quantities for comparison in phagocytosis tests with the in vitro grown strain from which they were derived.Microscopic and viable counts of gonococci in phagocytes showed that in vivo grown organisms (strain BSV) were readily phagocytosed by human polymorphonuclear phagocytes. There was little difference between BSV organisms and the in vitro grown organisms (strain BS) in resistance to ingestion. There was, however, a marked difference in the intracellular survival of strains BSV and BS during the first hour of phagocytosis. Whereas BSV organisms survived well, many BS organisms were killed. Subsequently, strain BSV and the survivors of the strain BS inoculum responded similarly to the intracellular bactericidins. These results were supported by electron microscopy of infected phagocytes.Resistance of gonococci in vivo to ingestion and digestion by human phagocytes seem to be important facets of the pathogenesis of gonorrhoea. INTRODUCTIONStrongly staining gonococci are seen both extracellularly and intracellularly in urethral pus from patients with gonorrhoea. The presence of extracellular organisms suggests overloading of phagocytic capacity and indicates that some gonococci in vivo may resist phagocytosis. However, the presence of intracellular organisms shows that phagocytosis occurs and, further, that gonococci may resist the intracellular bactericidins. Thus resistance to ingestion and digestion by polymorphonuclear phagocytes (PMN phagocytes), the predominant cell type in urethral pus, would be important in acute infection; and survival inside the fewer mononuclear phagocytes (MN phagocytes) could be important in chronic infection.Pilated (Dilworth et al., 1975). Thus, resistance to ingestion appears to be correlated with the virulence for man of the Kellogg types, but whether or not pili are responsible for the resistance is still a matter of dispute (Swanson et al., 1974).With regard to resistance to intracellular killing, appreciable numbers of a pilated, small-colony-forming strain of gonococcus (BS) resembling Kellogg type 2 survived and multiplied within human buffy-coat phagocytes (predominantly PMN phagocytes) over I 5 h and also survived for at least 6 h in the few MN phagocytes that could be separated from the buffy coat (Veale et al., I 976). A non-pilated, large-colony-forming strain (AL) resembling Kellogg type 4 survived at a much lower level than the BS strain and was destroyed in 10 to 12 h (Veale et al., 1976). Thus, with strains BS and AL, resistance to digestion could be correlated with infectivity for guinea-pig chambers (Veale et al., 1975) and, by analogy with the Kellogg types, with potential virulence for man. These...

S U M M A R YPhagocytes obtained from fresh human buffy coat (predominantly polymorphonuclear phagocytes) or from human buffy coat which had been incubated on a glass surface for I to 3 days (predominantly mononuclear phagocytes) were allowed to ingest gonococci, and then incubated with penicillin. More intracellular gonococci were killed at high than at low penicillin concentrations, indicating that penicillin penetrated the phagocytes. This was supported by autoradiography experiments with radiolabelled penicillin.A pilated, small-colony-forming gonococcal strain survived and multiplied for at least 15 h in polymorphonuclear phagocytes which were incubated with penicillin at the optimum concentration for killing the extracellular bacteria but not the intracellular ones ; whereas a non-pilated, large-colony-forming strain survived for only 10 h. The former strain survived for at least 6 h in similar experiments with mononuclear phagocytes. Intracellular survival and growth may be an important facet of the pathogenicity of gonococci.

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