Pathological features of experimental gonococcal infection in mice and guinea pigs

Abstract

The histopathological and immunofluorescent findings in tissues within and surrounding artificially created subcutaneous tissue cavities infected with Neisseria gonorrhoeae for 1 to 30 days were studied in mice and guinea pigs. Findings in the tissue cavities of the animal models were similar to the findings of disseminated gonococcal infection in humans. These similarities included an intense persistent polymorphonuclear leukocytic response with tissue necrosis, hemorrhage into the early lesion, a perivascular leukocytic response in adjacent tissue, difficulty in detecting large numbers of discrete morphologically typical gonococci by the tissue Gram stain and direct fluorescent antibody techniques, a decrease in the number of identifiable gonococci with duration of the infection, and moderate amounts of extracellular and intracellular immunofluorescent gonococcal debris. Studies into the pathogenesis of the animal infections may enhance our understanding of the pathogenic mechanism(s) associated with gonococcal infection in humans.There have been several recent reports on the survival ofNeisseria gonorrhoeae in artificially created tissue cavities in the subcutis of small laboratory animals (1, 2, 5). These animal models are now being used extensively to study the virulence and immunology of gonococcal infections (1-3, 5, 13). However, the pathological features of experimental infection have received little attention (3). For this reason, we report the histopathological and immunofluorescent findings in mouse and guinea pig tissues within and surrounding subcutaneous tissue cavities infected with gonococci for 1 to 30 days.MATERIALS AND METHODS Animals. (i) Guinea pigs. Adult Hartley strain guinea pigs (Cavia porcellus) weighing at least 750 g were used. Plastic 2-ml droptainer bottles without tops (Dougherty Bros. Co., Buena, N.J.) were surgically implanted into the subcutis along the dorsolateral flank of each animal. Prior to implantation, four elliptical openings were cut into the sides and a round opening was made in the bottom of each bottle (Fig. 1). At least 2 weeks was allowed between surgical implantation and bacterial challenge for the purpose of creating a connective tissue-lined cavity for the accumulation of tissue fluids.(ii) Mice. Adult, pathogen-free, ICR/Cds Swiss mice (Mus musculus) were used. Silicone rubber tubing (2-cm lengths, 3.2-mm inner diameter) (New Brunswick Scientific Co., New Brunswick, N.J.) was surgically implanted into the subcutis along the dorsolateral aspect of the back. At least 2 weeks was allowed between surgical implantation and bacterial challenge.N. gonorrhoeae. Isolate B, colony type 1 (7) N.gonorrhoeae, was initially obtained from a patient with gonococcal urethritis. This gonococcus was grown on GC base medium supplemented with Iso-VitaleX (Baltimore Biological Laboratories, Baltimore, Md.) (GCB medium) in a candle extinction jar for 18 h at 36.5 C. Cells were removed from GCB medium with sterile, cotton-tipped applicators and were suspended in Eagle minimal essenti...

Experimental animal infections with Mycoplasma hominis and Ureaplasma urealyticum

“…The other U. urealyticum isolate (26) infected five of six mice and one of six guinea pigs whose challenge inoculum contained viable mycoplasmas. The time period during which this mycoplasma isolate could be recovered from the mice ranged from 1 day to more than 4 months, and the guinea pig infections lasted 4 weeks, after which the animal spontaneously expelled its chamber.…”

“…The subcutaneous implantation of open chambers was first described in 1959 (8), and such chambers began to be used in infectious disease studies about a decade later (1,2,3). The technique used in this study is a modification of these earlier procedures (4,17,27).…”

Characterization of the immune response in subcutaneous chambers of guinea pigs immunized with a ribosomal preparation from Neisseria gonorrhoeae

“…Infection of guinea pig s.c. chambers with N. gonorrhoeae has been widely used as an animal model for gonorrhea. Several investigators, using live or Formalin-killed whole gonococci, have actively protected guinea pigs against experimental N. gonorrhoeae infection (2,7,13,15,23), and the sera from such immunized guinea pigs are capable of passively protecting (1,20). The outer membrane complex from gonococci has also been used as a protective immunogen in gonococcal infections in guinea pigs (5,6).…”

Vertebrate and Invertebrate Animal and New In Vitro Models for Studying Neisseria Biology

“…This in vivo study demonstrated how an intracellular stage enables the gonococcus to evade the innate immune response. The histopathological findings in tissues within and surrounding these chambers infected with gonococci were examined for up to 30 days in mice and guinea pigs [ 104 ]. The pathological findings are similar to those of disseminated gonococci infection (DGI) in humans, with polymorphonuclear neutrophil (PMNL) influx into the chamber and adjacent tissues, tissue necrosis and haemorrhage, accompanied by a steady decrease in the presence of gonococci [ 104 ].…”