The adherence of coagulase-negative staphylococci to smooth surfaces was assayed by measuring the optical densities of stained bacterial films adherent to the floors of plastic tissue culture plates. The optical densities correlated with the weight of the adherent bacterial film (r = 0.906; P less than 0.01). The measurements also agreed with visual assessments of bacterial adherence to culture tubes, microtiter plates, and tissue culture plates. Selected clinical strains were passed through a mouse model for foreign body infections and a rat model for catheter-induced endocarditis. The adherence measurements of animal passed strains remained the same as those of the laboratory-maintained parent strain. Spectrophotometric classification of coagulase-negative staphylococci into nonadherent and adherent categories according to these measurements had a sensitivity, specificity, and accuracy of 90.6, 80.8, and 88.4%, respectively. We examined a previously described collection of 127 strains of coagulase-negative staphylococci isolated from an outbreak of intravascular catheter-associated sepsis; strains associated with sepsis were more adherent than blood culture contaminants and cutaneous strains (P less than 0.001). We also examined a collection of 84 strains isolated from pediatric patients with cerebrospinal fluid (CSF) shunts; once again, pathogenic strains were more adherent than were CSF contaminants (P less than 0.01). Finally, we measured the adherence of seven endocarditis strains. As opposed to strains associated with intravascular catheters and CSF shunts, endocarditis strains were less adherent than were saprophytic strains of coagulase-negative staphylococci. The optical densities of bacterial films adherent to plastic tissue culture plates serve as a quantitative model for the study of the adherence of coagulase-negative staphylococci to medical devices, a process which may be important in the pathogenesis of foreign body infections.

Recent studies have indicated that the attachment of bacteria to mucosal surfaces is the initial event in the pathogenesis of most infectious diseases due to bacteria in animals and humans. An understanding of the mechanisms of attachment and a definition of the adhesive molecules on the surfaces of bacteria (adhesins) as well as those on host cell membranes (receptors) have suggested new approaches to the prevention of serious bacterial infections: (1) application of purified adhesion or receptor materials or their analogues as competitive inhibitors of bacterial adherence; (2) administration of sublethal concentrations of antibiotics that suppress the formation and expression of bacterial adhesins; and (3) development of vaccines against bacterial surface components involved in adhesion to mucosal surfaces. Progress has already been made in the development of antiadhesive vaccines directed against the fimbrial adhesins of several human bacterial pathogens.

Slime production is not a generally recognized feature of Staphylococcus epidermidis. In a recent outbreak of S. epidermidis intravascular catheterassociated sepsis, we noted that 63% of clinically implicated strains grew as a slimy film coating the culture tube walls when propagated in tryptic soy broth. Only 37% of randomly collected blood culture contaminants and skin isolates demonstrated a similar phenomenon (p < 0.05). Transmission electron micrographs of these coating bacteria showed them to be encased in an extracellular matrix that stained with alcian blue. Slime production was most evident in autoclaved media containing Casamino Acids and glucose supplementation (0.25% wt/vol). There were strain and media preparation variability of slime production in the presence of other carbohydrates. Some strains were not able to produce slime under any of the tested conditions. The production or nonproduction of slime did not influence growth rate. When grown in vitro, slime producers accumulated on the surface of intravascular catheters as macrocolonies, whereas non-slime, producers did not. Transmission and scanning electron micrographs showed slime producers to be encased in an adhesive layer on the catheter surface, whereas nonproducers were not encased. These results suggest that slime-mediated adherence may be a critical factor in the pathogenesis of S. epidermidis infections of medical devices.

The teichoic acids (TA) 1 of group A streptococci and other gram-positive bacteria are known to adsorb spontaneously to red blood cells (RBC) and a variety of other mammalian cells (1, 2). Such affinity of TA for cell membranes has been of special interest because (a) infections of TA can produce experimental nephritis (3) or arthritis (4) in laboratory animals by binding to tissue membranes and provoking local immunotoxic reactions; (b) it has been postulated (2) that TA may serve as a carrier of other streptococcal antigens and bind them to specific organ tissues where they could produce immunopathological lesions ; and (c) small amounts of TA may reside on the surface of virulent streptococci and, thereby, mediate their adherence to mucosal surfaces (5) . The component(s) responsible for TA binding to cell membranes, however, have not been clarified .The chemical composition and cell membrane affinity of streptococcal TA vary according to the method of extraction and purification . Matsuno and Slade (6) extracted TA with trichloroacetic acid (TCA) . This extract contained polyglycerolphosphate (PGP) and small amounts of alanine, hexoses, and hexosamines but was not able to sensitize RBC (7) . Jackson and Moskowitz (8) extracted TA with phenol . This extract contained PGP with relatively large amounts of ester-linked alanine, but no hexoses or hexosamines . In addition to alanine, Miller and Jackson (9) in preliminary studies observed the presence of small amounts of lipids in such TA preparations . Unlike the TCA extract, however, the phenol extract of TA was able to sensitize RBC spontaneously (8) .Similar observations were reported by Wicken, Knox, and Hewett (10-12) using Lactobacillus fermenti TA obtained by TCA and phenol extractions. Chorpenning and Stamper (13) reported that purified Bacillus subtilis TA obtained by phenol extraction was devoid of alanine and was capable of sensitizing RBC . In view of these studies, it was of interest to define more precisely the moieties of group A streptococcal TA involved in affinity for cell membranes in order to elucidate its possible role in pathogenesis of streptococcal diseases .The results of the present investigation indicate that small amounts of fatty acid moieties that are ester-linked to PGP play a major role in the affinity of streptococcal TA for mammalian cell membranes . Moreover, we present evidence to suggest that a portion of these moieties of TA are exposed on the surface * These studies were conducted

M protein was extracted from type 24, group A streptococci with pepsin at pH 5.8 and was further purified by ammonium sulfate precipitation, ribonuclease digestion, ion-exchange chromatography, and isoelectric focusing. The purified pepsin extract of M (pep M) protein was shown to be free of nontype-specific immunoreactivity in (a) complement fixation tests with heterologous M antiserum, (b) skin tests in normal adult guinea pigs, and (c) passive hemagglutination tests for the presence of lipoteichoic acid sensitizing or antigenic activity. The pep M24 was highly immunogenic; two of three rabbits developed opsonic antibody titers of 1:256 and the third a titer of 1:32 6 wk after a single injection of 100-pg doses of pep M24 emulsified in complete Freund's adjuvant. The antisera lacked nontype-specific antibodies and produced single precipitin lines in agar gel diffusion tests against crude HC1 extracts of the homologous M protein. Thus, the type-specific antigenic determinant(s) of type 24 M protein appears to be separable from immunotoxic, cross-reactive antigens without loss of immunogenicity in rabbits. The mobility of pep M24 upon electrophoresis in 10 percent sodium dodecyl sulfate pelyacrylamide gel was consistent with an average mol wt of 33,500 daltons. Amino acid analysis demonstrated a predominance of alanine, followed by glutamic acid, lysine, leucine, and aspartic acid. Pep M24 contained an estimated six to seven methionine residues and approximately ten phenylalanine residues per molecule. No other aromatic amino acids were detected. Automatic Edman degradation of pep M24 yielded the sequence of the first 29 amino acids (the amino terminal amino acid being valine) of the amino terminal region of the molecule. The detection of only one new amino acid at each step of Edman degradation confirmed the homogeneity of the purified pep M24.