A new colonial type of N. gonorrhoeae

Gonococcal color and opacity variants: virulence for chicken embryos

Previous studies have noted that the prevalence of certain gonococcal colony types is influenced by the physiological state of the human host. Consequently eight different gonococcal strains were passed on clear typing medium, and opaque (Op) and transparent (Tr) variants of heavily pilated (P++) bacteria were selected. P++Op and P++Tr were injected into 11-day-old chicken embryos, and the resulting mortality was determined. In every case the Tr variants were more lethal to the embryos than were the Op variants (P = 0.01). P++Tr were stable in vivo, but chicken embryos injected with P++Op strains developed bacteremia with P++Tr organisms. However, chicken blood was not bactericidal for either colonial variant. These results indicate that transparent pilated bacteria may be more virulent than opaque pilated bacteria and that in vivo selection of transparent forms occurs.

Attachment role of gonococcal pili. Optimum conditions and quantitation of adherence of isolated pili to human cells in vitro

Gonoccocal pili facilitate attachment of virulent Neisseria gonorrhoeae to human cells. To characterize this attachment function, purified gonococcal pili isolated from four strains possessing antigenically distinct pili were radiolabeled with 125I and used to measure the attachment of pili to various human cells in vitro. Human buccal and cervical-vaginal mucosal epithealial cells, fallopian tube mucosa, and sperm bound pili in greater numbers per micrometer2 of surface area (1--10) than fetal tonsil fibroblasts, HeLa M cells, erythrocytes, or polymorphonuclear leukocytes. This cell specificity of attachment suggests a greater density of membrane pili binding sites on cells similar or identical to cells from natural sites of infection. The pili binding sites were quantitated as 1 X 10(4) per cervical-vaginal squamous cell. Pili of all antigenic types attached equally to a given cell type, implying that the attachment moiety of each pilus was similar. Attachement of gonoccocal pili to human cells occurred quickly with saturation of presumed receptor sites within 20--60 min. Attachment was temperature dependent (37 degrees greater than 20 degrees greater than 4 degrees C), and pH dependent (3.5 less than 4.5 less than 5.5 less than 7.5). Attachment was inhibited by antibody to pili (homologous pili Ab greater than heterologous Ab). The extent of possible protection against gonococcal infection due to inhibition of pili-mediated attachment might prove limited as a result of the considerable antigenic heterogeneity among pili and the observation that blockage of pili attachment is maximal only with antibody to pili of the infecting strain.

Studies on gonococcus infection. XIII. Occurrence of color/opacity colonial variants in clinical cultures

Colonial variants of Neisseria gonorrhoeae differing in color and opacity characteristics are distributed differently between male urethral and female cervical cultures. Colonial characteristics of cultures isolated from female cervices differ with time of isolation within the menstrual cycle and use of oral contraceptives. These differences may reflect selective forces in the ecology of the cervix, particularly proteolytic enzymes in cervical mucus and menstrual blood. Cycle changes in the characteristics of gonococci isolated from females may have implications for pathogenesis of gonococcal infections and immune response to the gonococcus.

Isolation and characterization of a rough colony type of Neisseria gonorrhoeae

A new colony type of Neisseria gonorrhoeae was detected in the primary cultures from 8 of 180 men with gonococcal urethritis. This colony type contrasts with those previously described by having a rough and irregular surface. In six of the eight cases, the rough form predominated. The distinctive morphology of the rough colony variant could be maintained indefinitely by selective subculture. By electron microscopy, organisms taken from rough colonies of each of the eight isolates were piliated. Antimicrobial susceptibilities of type 1 and rough clones derived from the same patients were identical for ampicillin, penicillin, tetracycline, and spectinomycin. After inoculation of rough colonies into subcutaneous chambers in mice and guinea pigs, type 1 colonies predominated in cultures of material obtained from the chambers. This new piliated colony type of N. gonorrhoeae may provide an opportunity to investigate factors other than pili that contribute to gonococcal virulence.

Pili as a mediator of the attachment of gonococci to human erythrocytes

Isolated pure gonococcal pili were found capable of producing direct agglutination of human erythrocytes. Four different strains of gonococci were compared, and hemagglutination was produced by isolated pili or piliated gonococci but not by nonpiliated gonococci of each strain. Pili from each of the four strains were antigenically distinguishable using antisera specific for pili to agglutinate piliated gonococci, form precipitin lines in Ouchterlony immunodiffusion, or inhibit hemagglutination caused by purified pili or piliated gonococci. However, these tests also demonstrate some shared antigenicity among pili. Shared antigens among the four pili types were quantitated at less than or equal to 2.5% by radioimmunoassay. Inhibition of hemagglutination was most marked with antiserum to the homologous pili type. Inhibition of hemagglutination by antiserum to heterologous pili suggested that shared antigens on pili from B and 2686 strains of gonococci are located near the erythrocyte attachment moiety of B strain pili and removed from the attachment moiety of 2686 strain pili. These results suggest that antigenic heterogeneity of pili will prove an important factor in any efforts to use pili as a vaccine for gonorrhea.

Cultivation of type 1 N. Gonorrhoeae in liquid media

The effect of CO2 concentration on the growth and colonial stability of Type 1 Neisseria gonorrhoeae has been investigated. Carbon dioxide at a concentration of 16 per cent in air above flasks incubated in a shaker was effective in supporting growth and 100 per cent colonial stability of Types 1, 1', 2, and 4. Lower CO2 tensions increased the generation time of the strains and were less effective in maintaining the stability of virulent variants. Of several liquid media tested, Enriched Single Phase medium, which consists of Difco GC medium base (devoid of agar and starch) to which Lankford supplement and "Isovitalex" have been added, was the most suitable for use with small inocula.