Attempts to demonstrate a polysaccharide capsule in Neisseria gonorrhoeae

Abstract

Reimann, K., Heise, H. 8t Blom, J. Attempts to demonstrate a polysaccharide capsule in Neisseria gonorrhoeae. APMIS 96: [135][136][137][138][139][140] 1988.The presence or absence of a polysaccharide capsule on the human pathogen Neisseria (N.) gonorrhoeae is still a topic of controversy. For this reason we compared the results obtained by light microscopy (dry India ink-Fuchsin stain) and electron microscopy (Alcian blue-lanthanum nitrate stain) of encapsulated strains of N. meningitidis and Streptococcus (S.) pneumoniae and of non-encapsulated strains of S. pneumoniae and Escherichia (E.) coli with those obtained using the same methods on strains of pilliated and non-pilliated N. gonorrhoeae. After staining with India ink-Fuchsin no capsules could be demonstrated on any of the N. gonorrhoeae strains studied. If present the capsules on these cells are too delicate to be identified by light microscopy. After treatment with Alcian blue-lanthanum nitrate sections of cells of N. meningitidis and S. pneumoniae generally showed the presence of a capsular layer. Sections of cells of the non-encapsulated strain of S. pneumoniae which possess C (common)-polysaccharide also showed surface associated capsule-like material. Similarly the surface of the cells of the E. coli strain showed material which appeared to be tufts of pili and/or M (mucoid)-antigen. In experiments where the N. gonorrhoeae cells were harvested as early as after six hours of growth a capsule-like material was demonstrated on cells of all strains studied.

Demonstration of Polysaccharide Capsule in Campylobacter jejuni Using Electron Microscopy

“…Both whole bacteria (10) and thin sections (2,5,6,7,14) were used successfully. To avoid disturbing fragile capsular material, bacteria are often fixed and stained directly on agar plates, followed by thin-section analyses (7,14). Ruthenium red dye has also been used for staining bacterial CPS, for example, in Vibrio parahaemolyticus (4,5).…”

“…As in strain G1, a capsule was detected in wild-type strain X but not in the X kpsM::kan mutant (data not shown). The use of kpsM mutants in both cases was essential in eliminating the possibility of false-positive results due to a potential of Alcian blue to form aggregates and interact with other molecules on the cell surface (14).…”

“…A number of different approaches to stabilize capsules for EM visualization have been used, in- cluding treatment with antibodies, different dyes, and chemical cross-linking (2). Alcian blue has been used for staining capsules in several bacterial species, including Klebsiella pneumoniae (2), Neisseria gonorrhoeae (6,14), Bordetella bronchiseptica (10), Pasteurella multocida (5), and Haemophilus pleuropneumoniae (7). Both whole bacteria (10) and thin sections (2,5,6,7,14) were used successfully.…”

“…Alcian blue has been used for staining capsules in several bacterial species, including Klebsiella pneumoniae (2), Neisseria gonorrhoeae (6,14), Bordetella bronchiseptica (10), Pasteurella multocida (5), and Haemophilus pleuropneumoniae (7). Both whole bacteria (10) and thin sections (2,5,6,7,14) were used successfully. To avoid disturbing fragile capsular material, bacteria are often fixed and stained directly on agar plates, followed by thin-section analyses (7,14).…”

Functional characterization of the gonococcal polyphosphate pseudo-capsule

“…However, the absence of the region A in the capsule cluster of N. gonorrhoeae, responsible for the polysaccharide synthesis, precludes such possibility [7]. To this purpose, several groups attempted to demonstrate the evidence of capsular material through electron microscopy, producing inconsistent results [7][8][9][10][11][12]. Noegel and Gotschlich in 1983, isolated high molecular weight polyphosphate (polyP) located outside the cytoplasmic membrane of N. gonorrhoeae and proposed a possible role as capsule-like material [13].…”