Detection of Capsular Antigen Production in Unencapsulated Strains of Staphylococcus aureus

Abstract

Of 91 compact-type strains of Staphylococcus aureus in regular serum soft agar (SSA), 82 converted diffuse-type growth in serum soft agar (pH adjusted to 6.0). With the addition of four different rabbit anticapsular sera (anti-type A, B, C, and D sera) in low pH (6.0) SSA, 21 strains of S. aureus showed compact-type colonial morphologies. Eleven, one, and one strains of S. aureus reacted singly with rabbit anticapsular sera types A, B, and C, respectively, and no strain reacted with rabbit anticapsular type D. Eight of these strains reacted with both rabbit anticapsular sera types A and B. When the ability to absorb the converting activities of the antisera (changes of colonial morphologies of anticapsular sera in SSA) was quantitatively tested, 7-to 27-fold of these organisms were capable of absorbing the activities compared with the Smith diffuse organisms. These results suggest that even unencapsulated S. aureus strains are capable of producing capsular substance, although the capability is quantitatively different from strain to strain.on August 1, 2020 by guest http://iai.asm.org/ Downloaded from

Application of Fluorescent Antibody for Detecting Capsular Substances in Staphylococcus aureus

“…The FA technique has confirmed the results of capsular typing obtained with the SAA technique in spite of the fact that encapsulated strains were regarded generally as exceptional among the staphylococci. These results matched the findings obtained by electronmicroscopy (Yoshida & Minegishi 1975). The relationship of capsular-type to biochemical and immunological properties of cell wall teichoic acid preparations reported by Ohtomo et al (1976) agree with these findings especially those obtained with unencapsulated strains.…”

“…Furthermore, much emphasis has been given to production of a capsular substance by Staph. aureus strains (Ekstedt & Yoshida 1969;Yoshida et al 1969;Yoshida et al 1970;Yoshida 1970;Yoshida et al 1974;. The FA technique has confirmed the results of capsular typing obtained with the SAA technique in spite of the fact that encapsulated strains were regarded generally as exceptional among the staphylococci.…”

“…Wiley & Maverakis (1968) found a 46% incidence of anti-capsular antibody in mice. Yoshida & Minegishi (1975) showed specificities of anticapsular rabbit sera related to capsular-type in the demonstration of capsule and capsular production even in unencapsulated strains of Staph. aureus by electronmicroscopy.…”

“…Strains exhibiting biological properties such as negative clumping factor reaction, diffuss-type growth in the SSA and phase non-typability were regarded as encapsulated according to the criterion described by Witte (1957) and Yoshida & Minegishi (1975). The value of the capsular swelling phenomenon had been neglected by Mudd & DeCourcy (1 965) who designated it as an extracellular peripheral precipitin reaction.…”

“…aureus by the serum-soft agar (SSA) technique. With a modification of this technique, Yoshida et al (1974) found evidence that capsular substance was produced even in so-called unencapsulated strains of Staph. aureus.…”