Neisseria gonorrhoeae. Colony variation I

Prolonged survival of Neisseria gonorrhoeae in a new liquid medium

Despite substantial improvements in solid culture media for gonococci and the development of liquid media for the short-term growth of the organism, we know of no study of the long-term survival of Neisseria gonorrhoeae in liquid medium. A new liquid medium for N. gonorrhoeae formulated in this laboratory is simple, efficient, and promising. It will support growth and sustain inoculated colony types for periods of up to 3 weeks. Moreover, it has been used successfully for the primary isolation of gonococci from patients. From the evidence at present available, we believe that this medium will find a useful place in gonococcal research.

Bacterial hemagglutination by Neisseria gonorrhoeae

Direct bacterial hemagglutination was investigated with 20 clinical isolates of Neisseria gonorrhoeae. The hemagglutination tests were performed by both a macrotechnique with glass slides and a microtechnique with autotrays. Only organisms from form type 1 or 2 colonies caused hemagglutination. There was no statistical difference at a 10% or higher level in hemagglutination powers of type 1 and type 2 organisms, of male urethral and female cervical isolates, and of the eight major human blood types (ABO-Rh). Of seven erythrocyte species tested, only human cells were agglutinated. D-Mannose did not prevent the agglutination. Rabbit antigonococcal serum and high-titer antigonococcal human sera inhibited the hemagglutination. The results suggest the pili are the mediators of hemagglutination and that their specific agglutination of human erythrocytes may be a correlate of their adherence to human mucosal cells in natural infection. Also, although the procedure is presently insensitive, it is possible to detect human antigonococcal antibody by inhibition of direct bacterial hemagglutination.

A new colonial type of N. gonorrhoeae

A new variant of Neisseria gonorrhoeae, designated Type 1(1), is described. Colonies of the new type resemble those of Types 1 and 2 in physical characteristics but are granular with a slightly crenated edge and are a deeper gold in colour. The virulence of Type 1(1) in the chick embryo is in keeping with that of Types 1 and 2 but is significantly different from Types 3, 4, and 5. Type 1(1) could be maintained in the laboratory for 6 months, provided that daily selective subcultures were performed. In the absence of this, Type 1(1) reverted to Type 5. It was also possible to preserve the stability of Type 1(1) for long periods by immersion in liquid nitrogen. Pili have been demonstrated on the new type.

Acquired and natural immunity to gonococcal infection in chimpanzees

Despite the fact that gonorrhea is our most common reportable infectious disease, little is known about natural and acquired resistance to Neisseria gonorrhoeae. With the chimpanzee model, which mimics human gonococcal infection in signs, symptoms, and host response, a natural resistance to gonococcal challenge was found. One aspect of this natural resistance became evident when the cervix and oral pharynx resisted more gonococci than the urethra. Natural resistance was also shown when environmental factors were found to influence resistance to gonococcal pharyngitis. In addition to natural resistance a postinfection-acquired immunity to the gonococcus was demonstrated. Following gonococcal pharyngitis, this anatomical location successfully resisted more gonococci than were initially resisted. Similarly, more gonococci were successfully resisted in rechallenging the urethra. These findings are related to the clinic situation and suggest possible new approaches to gonorrhea control.

Neisseria gonorrhoeae auxotyping: differentiation of clinical isolates based on growth responses on chemically defined media

A system is described for differentiating clinïcal isolates of Neisseria gonorrhoeae based on their growth or absence of growth on a set of 11 chemically defined agar media. The complete medium, NEDA, contains all of the compounds required for gonococcal growth; but isolates differ in their ability to grow on NEDA from which selected compounds are individually omitted. The differential compounds include L-proline, L-arginine, L-ornithine, L-methionine, hypoxanthine, uracil, thiamine, and thiamine pyrophosphate. A distinctive pattern of growth responses on the standard media defines an auxotype. Twenty auxotypes were found among a group of 251 gonococci which were isolated from patients examined in the clinics of one city during a 3-month span of time. Another collection of 74 strains from several different countries yielded two additional auxotypes. The stability of the nutritional requirements on which the auxotyping depends was verified in two ways. Cultures isolated from different anatomic sites of a patient or from sexual partners represented the same auxotype, as did cultures which were repeatedly isolated from cases of presumptive treatment failures. Also, the auxotypes of gonococci remained the same after numerous subcultures. The reproducibility of results and the variety and number of auxotypes indicate the potential value of the auxotyping system as an epidemiological tool.