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Staphylococcus aureus strain S-6, which produces enterotoxin type B (SEB), and strain 10-275, a high toxin-producing mutant derived from S-6, display pronounced differences in dye sensitivity, osmotic stability, and bacitracin sensitivity. Such characteristics are consistent with the concept that strain 10-275 is a membrane mutant of strain S-6. Some membrane mutants of S. aureus strain 14458 exhibit about two- to three-fold increases in SEB production whereas other membrane mutants show about twofold increases in alpha-hemolysin production. It is suggested that specific and independent membrane mutations control the secretory processes resulting in the extracellular elaboration of these exoproteins. more...

Microorganisms were absent in the remaining pulp stumps of twenty teeth which had been exposed to caries and contaminated at the pulpal chamber level. We have demonstrated that microorganisms are not carried to the deepest areas of the pulp when the basic procedure is strict antisepsis applied to the living pulp stump. A sterile and living pulp stump wound contributes to an adequate biologic sealing of the apical foramen. Of all the isolated microorganisms, the alpha hemolytic Streptococcus was most frequently found in all examined cases, in pure or mixed cultures, demonstrating once again he prodominance of that type of microorganism when pulpal injury occurs. more...

Novel bacterial structures have been demonstrated in lysed blood filtrates placed in special culture media from patients with idiopathic hematuria. These structures converted rapidly to gram-positive coccal (streptococcal and staphylococcal-like) coccobacillary and filamentous, bacterial forms in vitro from 96 per cent of the patients studied. Blood cultured conventionally yielded negative findings. Although structures (dense bodies) were demonstrated in normal control blood specimens (albeit in lesser numbers) few converted to classical bacteria in vitro (7 per cent). Erythromycin therapy appeared to correlate with disappearance of hematuria and inability to revert rapidly the variant froms to classical bacteria in vitro. It is suggested that continual bombardment of the blood by bacteria entering from the mouth or other sites may lead to the development of variant bacterial parasitism. In an effort to survive the deleterious host effects the organisms may convert to persisting osmotically stable variant bacterial forms (dense bodies). Development of a disease state may be conditioned by some existing or developing abnormality in the host (immunologic, physiologic and/or biochemical). Furthermore, changes (genetic?) that might take place in the organisms per se during their transition to variant forms and adaptation to life in vivo may not allow certain host environments to adapt to these new forms, possibly leading to a pathogenetic role in renal diseases whose etiologies have long been enigmas. more...

The cell wall of Staphylococcus aureus was shown to undergo turnover during exponential growth. The rate of turnover, about 15% per generation, was identical for both cell wall polymers, peptidoglycan and teichoic acid. Both the old and newly synthesized wall material appeared to undergo turnover at similar rates. The rate of turnover followed first-order kinetics until more than 90% of the original wall was lost. Cell wall turnover was completely blocked under conditions of unbalanced synthesis known to inhibit cellular autolysis, e.g., addition of chloramphenicol. Cell wall turnover was shown to occur in a number of different strains of S. aureus and appears to be widely distributed in this species. more...

The hydrophobicity-hydrophilicity of various strains of Staphylococcus has been studied by a technique involving partitioning of the cells between aqueous and hydrocarbon phases. S. aureus was typically hydrophobic, and to a greater degree in stationary- than in exponential-phase cultures. Mutants that lacked teichoic acid, protein A or coagulase production were hydrophobic, indicating that none of these factors was responsible for hydrophobicity. The presence of a capsule rendered strains hydrophilic. Thus, determination of hydrophobicity may be a useful additional test for capsulation. However, a non-capsulate S. aureus strain was hydrophilic. Trypsin treatment converted strains from hydrophobic to hydrophilic. Isolated bacterial cell wall preparation, either crude or purified, and peptidoglycan were hydrophilic. These results indicate that the determinant of hydrophobicity is a protein or protein-associated molecule localised at the cell surface of the organism, i.e., a component of either the cell wall, cell membrane, or both. Twenty-five strains of twelve coagulase-negative species were examined and most (18) were hydrophobic, again indicating that protein A is not a major determinant of hydrophobicity in these staphylococci. Four of seven hydrophilic strains were capsulate; three strains of S. sciuri were hydrophilic but non-capsulate. more...

An encapsulated strain of Staphylococcus simulans (strain 76) isolated from a clinical case of bovine mastitis was demonstrated by the India ink technique, using both a light microscope and an electron microscope. The strain failed to kill mice after intraperitoneal inoculation but resisted ingestion by peritoneal phagocytic cells. The behavior of the strain helps to delineate the antiphagocytic role of the capsule. more...

The effect of highly purified staphylococcal alpha-toxin on HEp-2 neoplastic cells growing in culture was studied by electron microscopy. In addition to some nuclear modifications, the most significant morphological changes were in mitochondrial structure, alpha-toxin seems to induce a defined sequence of changes in mitochondrial configuration which can be summarized as an earlier phase of 'condensation' of mitochondrial structure and a later phase of mitochondrial swelling with an intermediate 'transitional' configuration. The significance of these findings is discussed in the light of the present state of knowledge of the biological characteristics of staphylococcal alpha-toxin. more...

The specific antigenicity of pentaglycine bridges in cell walls of S. aureus was investigated. The antistaphylococcal sera (against 11 Oeding strains of S. aureus) were found to contain antibodies of two different specificities against polyglycyl peptides; one type reacted with polyglycyl peptides with a free amino terminus and the other with polyglycyl peptides with a free carboxyl terminus. These antibodies were assayed by passive hemagglutination with tanned sheep red cells sensitized with N-polyglycyl-BSA (containing polyglycyl peptides with a free amino terminus) or with C-poe antibodies against N-polyglycyl peptides were absorbed by S. aureus strains and by S. epidermidis. Heterologous bacterial species failed to absorb antibodies of either specificity. Antibodies against polyglycyl peptides were used to confirm the mechanism of action of penicillin on S. aureus cell wall. more...

The process of cell separation and arrangement of Staphylococcus was investigated using a scanning electron microscope. After two cycles of cell division, the Staphylococcal cells cultured on an agar medium were generally observed to be arranged in three morphological types: linear, square, and crooked arrangements. Results of the examination of cell surface structure revealed that separations had occurred in these clustered cells following two patterns. One type of second separation occurred parallel to the transversal axis of the preceding pair of the parental cells (X-type) and the other occurred tangential to it (Y-type). In the former type, the four daughter cells were usually arranged tetragonally after the separations, and in the latter type they were arranged either linearly or crookedly depending on the direction of the second separation. The final pattern of the cell arrangement was thus determined by the type of septal wall formation and the direction of cell separation. After several cycles of cell divisions, the cells were finally arranged in an irregular grape-like cluster, even though the cross walls were formed regularly at the rectangular face of the preceding cross walls. more...

A strain of Staphylococcus aureus was planted on filter membranes placed on Trypticase soy agar (BBL). After incubation, the membranes with growing staphylococci were transferred to Trypticase soy agar containing a subinhibitory concentration of penicillin (one-third minimal inhibitory concentration) and again incubated. The membranes were then returned to drug-free agar and incubated once more. Counts of the colony-forming units and electron microscopy were carried out at several time intervals. When grown on agar containing penicillin, the staphylococci formed what appeared to be abnormally large cells with multiple and unusually thick septa. Examination of a number of sections showed that these large cells were in reality clusters of staphylococci that had divided but failed to separate. When these large cells were subsequently grown on drug-free agar, smaller cells and normal staphylococci emerged. Subinhibitory concentrations of penicillin do not kill staphylococci; they seem to inhibit lysis of cross walls, preventing the separation of otherwise divided cells. more...

The nature and extent of the immune dysfunctions in 20 immunodeficient patients, as well as the immunocompetence of 22 control subjects, were verified by cell-mediated responsiveness and immunoglobulin quantitations. Comparisons of the microbial composition of supragingival plaque between the two populations showed that a greater number of immunodeficient than control subjects harbored Candida sp. and Staphylococcus sp. Conversely, a lower number of immunodeficient than control subjects harbored Streptococcus mutans. Also, patients with immune dysfunctions had a lower dental caries experience than their immunocompetent counterparts. more...

The laboratory conditions for reproducible routine determination of staphylococcal cell-surface hydrophobicity by the salt aggregation test were standardized. Fresh bacterial suspensions standardized to 5 x 10(9) cfu/ml gave the most reproducible results with both Staphylococcus aureus and coagulase-negative staphylococci. For relatively hydrophobic strains a 5-min reading time was necessary to detect bacterial aggregation in ammonium sulphate solutions ranging from 0.1 M to 1.5 M, pH 6.8. A x 10 hand lens facilitated reading aggregations. Overnight storage of bacterial suspensions at 20 degrees C reduced cell-surface hydrophobicity of all species, while storage at 4 degrees C reduced the hydrophobic nature of Staph. aureus strains. The hydrophobicity of coagulase-negative staphylococci rarely changed at 4 degrees C. A 10-fold dilution of fresh, standardized bacterial suspensions made it impossible to detect bacterial aggregation in ammonium sulphate solutions even with a hand lens. Under standardized conditions three types of staphylococcal cell aggregations were observed. The first looked like the slide agglutination for O antigens of Enterobacteriaceae, the second resembled H-agglutination, while the third had a filamentous appearance. These patterns indicated that more than one component might contribute to cell-surface hydrophobicity of both Staph. aureus and coagulase-negative staphylococci, or the same component might have different position on the cell surface. more...

Small-cell formation of Staphylococcus aureus by subinhibitory concentration of nitrofuran derivatives was examined by scanning and transparent electron microscopy.

The composition of the monomeric unit of staphylococcal peptidoglycan has been known since the late 1960s. However, the three-dimensional structure of this macromolecule has been unclear. Staphylococci divide with expansion of a central cross wall into a peripheral hemisphere under conditions that suggest that additional monomers are not introduced, but rather that the shape of existing monomers is changed. The monomeric unit can be divided into a glycan chain piece, a connecting peptide, and a peptide chain piece, which define a solid parallelogram. In the proposed model, appropriate change in the angle of the glycan chain with respect to the peptide chain doubles the surface, as required to deform cross wall into peripheral wall. Furthermore, cross wall peptidoglycan is synthesized in a spiral, which becomes deformed into a spiral to form peripheral wall, and the glycan chain is twisted with two disaccharide units per turn. Insights from the model can be applied to other peptidoglycans and can help explain the mechanism for start of cell division, the functions of various penicillin-binding proteins, the method of resistance to methicillin, and the occurrence of osmotically growth-dependent bacteria. more...

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. more...

The present environment of cost containment frequently forces laboratories to reassess various strategies for the diagnostic work-up of patient specimens. The necessity for the performance of antimicrobial susceptibility testing on all morphologic variants of blood culture isolates was examined in this study. Over a 4-year period, of 143 such organisms that were identified, 56 (39%) exhibited clinically significant differences in antibiogram profiles. Coagulase-negative Staphylococcus represented the largest proportion of isolates (n = 115), 39% of which demonstrated clinically significant differences in antibiograms. The authors conclude that these results justify the current practice in their laboratory of performing separate antimicrobial susceptibility testing on all morphologic variants of isolates. more...

Certain antibiotic compounds including penicillin, cloxacillin and 6-APA caused a prolonged survival of Staph. aureus cells undergoing autolysis in physiologic saline. The retardation of the death rate was dependent upon the type of compound and its concentration. The results suggest that the compounds inhibit the autolytic function of the bacteria. more...

The characteristics of light scattering of cell suspensions in norm (pH 7,2, t=20degreesC) and upon external influences (change of pH and increase of tdegree). The turbidity tauapproximatelylambda-n and n=0,2--0,3 for cells in norm. After cell damage n increases. Dependence of n correlates with the increase of some injured cells determined by eozin test. Alterations of light scattering after cell damage were connected with the increase of deposit of intercellular structure in general scattering. more...

A model was established for the study of adhesiveness and invasiveness of staphylococcal species. Five collection strains from each of the species Staphylococcus aureus, S. epidermidis, and S. saprophyticus and 26 fresh isolates from patients with urinary tract infections were tested for adhesiveness and invasiveness in HEp-2 cell cultures. All the strains of S. saprophyticus were able to invade the cells and localize intracellularly in the cultures, whereas the invasive potential among the strains of S. aureus and S. epidermidis was lower. The number of adhesive bacteria was also highest among the S. saprophyticus strains, whereas S. epidermidis was the least adhesive. The model may be suitable for further study of urinary tract infection strains. more...

1. Ribitol teichoic acids prepared by fractional precipitation of trichloroacetic acid extracts of bacterial cell walls are essentially undegraded and have similar chain length to the teichoic acid originally present in the walls. 2. The chain length of teichoic acid can be determined directly, without prior extraction from the wall. Accurate values have been obtained by measurement of the formaldehyde produced by oxidation of walls with periodate. Less accurate values have been derived from the amount of inorganic phosphate formed by heating walls at pH4. 3. The relative amounts of N-acetylglucosaminylribitol and its mono- and di-phosphates produced by heating walls of Staphylococcus aureus with alkali agree with the amounts calculated for the hydrolysis of teichoic acid having the chain length determined by other methods. 4. Chemical considerations indicate that the linkage between teichoic acid and the wall may involve a phosphoramidate bond between the terminal phosphate of the teichoic acid and one of the amino groups in the glycosaminopeptide. more...

The Smith diffuse variant and the wound mucoid strain of Staphylococcus aureus were shown to exhibit serologically distinct capsules. The Welwood and K-6 strains of S. aureus were tested to determine their capsular types. Both Welwood and K-6 were found to be representative of the Smith capsular type. An additional 13 isolates of S. aureus from mice were tested. Gel double-diffusion tests and immunoelectrophoresis of staphylococcal antigens disclosed the possible existence of at least two additional capsular types. Passive hemagglutination tests carried out with cells sensitized with 1 mg of antigen per ml showed a multiplicity of cross-reacting antigens. However, cells sensitized either with 0.1 or 0.05 mg of antigen per ml and reacted with antisera absorbed with 10 or 1 mug/ml showed the presence of a specific antigen in each strain of S. aureus. Corroborative evidence for a multiplicity of capsular types was obtained by the specific capsular reaction. At least four capsular types of S. aureus were found. The prototypic strains for these antigens are the RLM or wound strain, the Smith diffuse strain, and mouse strains designated 36T and 43R. We propose to designate these types 1, 2, 3, and 4, respectively. more...