Coagulase-positive Strains Research Articles

Virulence Mechanisms Of Staphylococci Grown In Vivo And In Vitro

Summary A coagulase-positive strain of Staphylococcus aureus grown in vitro (strain O) was passaged in rabbits to increase virulence. The passaged organisms grown in vitro (strain P) were used to infect rabbits from which organisms grown in vivo (strain V) were isolated. By LD50 measurement in rabbits, strain V was 25 times more virulent than strain P and 6000 times more virulent than strain O. On incubation in rabbit serum, strain V multiplied whilst strains P and O decreased in viable number (strain O the more rapidly) during the first 3 hr, recovering subsequently. In lysates of polymorphonuclear leucocytes, strain V multiplied or was slightly reduced in number; strains P and O decreased in number (strain O the more rapidly). The findings suggest that resistance to serum and polymorph bactericidins is an important attribute of the virulence of staphylococci and that the substances responsible are qualitatively different or quantitatively increased on growth in vivo.

Effect of Borate on the Growth of Coagulase-Positive and Coagulase-Negative Staphylococci

Of 235 strains of coagulase-positive Staphylococcus aureus studied, 221 or 94% were inhibited by 1.5 x 10(-8)m sodium borate, whereas only 6 of 57 (10.5%) coagulase-negative strains were inhibited by the same borate concentration. Four of the six coagulase-negatives were food poisoning strains and one was a hospital pathogen. Borate sensitivity was found to correlate well with lysozyme and alpha-toxin production by coagulase-positive strains.

患者由来表皮ブドウ球菌に関する研究

Fifteen strains of Staphylococcus epidermidis were isolated from the blood of patients of septicemia. They produced white colonies, except two strains, and were negative for both coagulase and egg-yolk tests, indicating that they were of S. epidermidis in its literal meaning. Some of them were positive for both hemolysin and DNase (deoxyribonuclease) formation. When inoculated into mice by the subcutaneous or intraperitoneal route, all of them produced subcutaneous or intraperitoneal abscesses, except 4 strains. When inoculated by the intravenous route, 5 strains caused hemorrhagic or suppurative lesions in the kidneys, but none of the others induced lethal infection, except coagulase-positive strains used as controls.

Biological properties, drug sensitivity and phage types of staphylococci isolated from rats (Rattus norvegicus) and swine

In order to search for the source of staphylococci responsible for food poisoning, studies were made on some properties of staphylococci isolated from rats (Rattus norvegicus) and swine, both of which had close relations with human beings. These staphylococci had been isolated from the nose of swine and the skin of rats. Coagulase-positive staphylococci were derived from 65 (50%) of 130 rats and 58 (85%) of 68 swine. These isolates were proved to have the following biological characters, drug sensitivity, and phage type.1. All the strains of coagulase-positive staphylococci isolated from rats and swine produced DNase, phosphatase and lysozyme, and reduced nitrate.2. Only 34 percent of the coagulase-positive strains isolated from rats showed β hemolysis, while almost all the strains (97%) isolated from swine were β hemolytic.3. The biological properties of the strains of rat origin were not always the same as those of swine origin. There were differences between the two in such respects as colonial color, lipase production, gelatin liquefaction, coagulation and later peptonization of litmus milk, hydrolysis of esculin, and egg reaction.4. Forty percent of the strains of rat origin were relatively resistant to penicillin, showing a susceptibility higher than 25u/ml. Thirty-five percent of the strains of rat origin and 83 percent of those of swine origin were relatively resistant to streptomycin (susceptibility higher than 12.5mcg/ml). Only 13 percent of the strains of swine origin were relatively resistant to tetracycline (higher than 12.5mcg/ml). About 80 percent of the strains isolated from both animal species were resistant to sulfathiazole (higher than 100mcg/ml). All the strains tested, however, were sensitive to chloramphenicol, oleandomycin, and erythromycin (less than 6.3mcg/ml). All the strains that were relatively resistant to penicillin and streptomycin formed yellow colonies on solid medium and were proved to be α hemolytic.5. Typing was carried out on these isolates using the basic set of typing phages which has been selected by the International Committee. Eighty-one percent of 58 strains of swine origin were successfully typed. Three-fourths of the strains which had been typed by this set of phages showed susceptibility to group II, and the rest of them belonged to the mixed group. On the other hand, only 17 percent of the strains of rat origin was found to be typable and belong to group III without exception.6. It can generally be mentioned that the properties of some of the strains of rat origin were closely related to those of the strains isolated from the cases of staphylococcal food poisoning, while the strains isolated from swine were considerably different from those from human beings.From these results, it is quite probable that the rat is playing an important role as a source of contamination in the case of staphylococcal food poisoning.

Lysozyme production as an aid for identification of potentially pathogenic strains of staphylococci.

Lysozyme production is a frequent property of potentially pathogenic staphylococci. In the present study, 1,186 strains of human origin, 85 strains of animal origin, and 156 strains of Staphylococcus albus (epidermidis) were tested. Of 1,114 coagulase-positive strains of human and animal origin, 1,098 were lysozyme-positive (98.5%). On the other hand, of 157 coagulase-negative strains which, based on further investigations, belong to the potentially pathogenic staphylococci, all were lysozyme-positive. All of the 156 strains (100%) belonging to the species S. albus (epidermidis) were lysozyme-negative. We conclude that lysozyme production is a better index of potentially pathogenic staphylococci than the measurement of free coagulase, especially in cases of strains of animal origin. It is possible that lysozyme production allows a differentiation between pathogenic and nonpathogenic coagulase-negative staphylococci.

Inhibition of fibrinogen reaction by polysaccharide of encapsulated Staphylococcus aureus.

Encapsulated and nonencapsulated strains of Staphylococcus aureus which lack coagulase or clumping factor (bound coagulase), or both, were examined for the antigen associated with the fibrinogen-cell clumping reaction. Extracts of the cells were tested for the ability to react with fibrinogen or to inhibit fibrinogen precipitation. Antisera prepared against encapsulated (coagulase-positive, clumping factor-negative) variants, as well as against nonencapsulated wild-type (coagulase-positive, clumping factor-positive) S. aureus strains, contained high titers of clumping-inhibiting antibody. When coagulase-negative, clumping factor-negative mutants were the immunizing agents, antisera contained no demonstrable clumping-inhibiting antibody. Phenol extracts of all coagulase-positive strains tested precipitated fibrinogen, regardless of the ability of cells to clump in the presence of fibrinogen. Polysaccharide extracts of encapsulated, clumping factor-negative strains inhibited this fibrinogen-precipitating activity, whereas similar extracts of nonencapsulated staphylococci did not inhibit the fibrinogen reaction. From these results, it appeared that the coagulase-positive, encapsulated staphylococci which do not clump in fibrinogen solution possess clumping factor, but that their capsular polysaccharide inhibits clumping activity. These findings suggested a closer association of clumping factor and coagulase than is now recognized.

Susceptibility of coagulase-negative staphylococci to lysostaphin and other antibiotics.

In general, coagulase-negative staphylococci were found to be relatively less susceptible to the lytic action of lysostaphin than coagulase-positive staphylococci. To achieve, arbitrarily, a lysis greater than 75%, it was necessary to use an increased concentration of enzyme or a longer incubation period than that usually required with coagulase-positive strains. For the most part, the cultures studied were sensitive to oxacillin, cloxacillin, dicloxacillin, nafcillin, ancillin, cephalothin, cephaloridine, fusidic acid, lincomycin, novobiocin, and neomycin [median minimal inhibitory concentrations (MIC) of 1.56 mug/ml or less]. Some degree of resistance (median MIC values of 12.5 mug/ml or greater) to benzylpenicillin, ampicillin, methicillin, tetracycline, chloretetracycline, erythromycin, ristocetin, and lysostaphin was found. Ten methicillin-resistant, coagulase-negative staphylococal strains were found to be cross-resistant to all nine of the penicillins tested, but much less resistant to the two cephalosporin analogues. In several instances, some of these strains seemed to be more sensitive to benzylpenicillin and to certain of the semisynthetic penicillins than to methicillin. Of the 18 antibiotics tested with the viable plate count method, the methicillin-resistant strains were found to be the most sensitive to lincomycin and novobiocin.

Susceptibility of Coagulase-negative Staphylococci to Lysostaphin and Other Antibiotics

In general, coagulase-negative staphylococci were found to be relatively less susceptible to the lytic action of lysostaphin than coagulase-positive staphylococci. To achieve, arbitrarily, a lysis greater than 75%, it was necessary to use an increased concentration of enzyme or a longer incubation period than that usually required with coagulase-positive strains. For the most part, the cultures studied were sensitive to oxacillin, cloxacillin, dicloxacillin, nafcillin, ancillin, cephalothin, cephaloridine, fusidic acid, lincomycin, novobiocin, and neomycin [median minimal inhibitory concentrations (MIC) of 1.56 mug/ml or less]. Some degree of resistance (median MIC values of 12.5 mug/ml or greater) to benzylpenicillin, ampicillin, methicillin, tetracycline, chloretetracycline, erythromycin, ristocetin, and lysostaphin was found. Ten methicillin-resistant, coagulase-negative staphylococal strains were found to be cross-resistant to all nine of the penicillins tested, but much less resistant to the two cephalosporin analogues. In several instances, some of these strains seemed to be more sensitive to benzylpenicillin and to certain of the semisynthetic penicillins than to methicillin. Of the 18 antibiotics tested with the viable plate count method, the methicillin-resistant strains were found to be the most sensitive to lincomycin and novobiocin.

ブドウ球菌の菌体外酵素に関する研究

The authors determined the optimal conditions for the lysozyme activity test to identify pathogenic staphylococci from various points of view. Besides, in an attempt to apply this test as a routine method, the usefulness of a modification of this test was checked as to a number of staphylococcal strains freshly isolated from human clinical materials. These strains were for interrelationships among coagulase, deoxyribonuclease, and other biological attributes. The results obtained are summarized as follows.1) The optimal conditions were determined for checking the lysozyme activity of staphylococci by means of the agar plate method. For this purpose was used a plate of ca. 15ml of “lysozyme agar”, which consisted of heart-infusion agar (Eiken), 40g; acetone-dried cells of the Miccrococcus lysodeikticus ATCC 4698 strain, 1g; and distilled water, 1, 000ml, and which had been adjusted to pH 7.1±0.1. It was streaked, ca. 1cm long, with one loopful of the test organisms and incubated overnight at 37°C. After an incubation at 37°C for 24 hours was made the judgment. When a transparent zone was observed obviously around the colony formed, the test was regarded as positive, or the test strain was regarded as a lysozyme-producer. It was confirmed that under such conditions the zone was the clearest and widest.2) By using this method, 509 strains isolated freshly were examined for lysozyme activity. As a result, a considerably good correlation was seen with coagulase production. Of 313 coagulase-positive strains, 349 were lysozyme-positive (98.9%). Of 153 coagulase-negative strains, 34 were lysozyme-positive (21.8%). This result was almost the same as that given by the phenolphthalein phosphatase test. It was a little inferior to that given by the DNase test, which showed such a close correlation as that obtained in the preceding investigation. The gelatin liquefaction, mannitol fermentation, and egg-yolk test were, however, considerably low in correlation with the coagulase test. This was especially the case with the coagulase-negative strains.3) The grades of enzyme activity of the test strains were measured by the turbidity method and expressed in terms of lytic index. Fifty strains each of Staphylococcus aureus and S. epidermidis were selected arbitrarily from the above strains. All the coagulase-positive strains were over 30 in lytic index. All the coagulase-negative strains were less than 20, except 3 strains which were a little higher.Thus, it may be concluded that the lysozyme activity test is useful, as a routine method, for identification of pathogenic staphylococci, especially when carried out in combination with the coagulase and DNase test.

Effects of exogenous purines on growth rates and other properties of Staphyloccus aureus strains including a pyrimidineless mutant of the Wood 46 strain.

Growth inhibition by adenine or adenosine and its reversal by other purines were quantitatively different in the four Staphylococcus aureus strains we have studied. After 11 hours, 0.25 μmole/ml adenine or adenosine reduced growth by 6 and 4%, respectively, in the coagulase-negative SA-13 strain, by 35 and 35% in the tryptophan-dependent Smith strain, by 68 and 98% in a Wood 46 thymineless mutant strain, and by 40 and 37% in the parent Wood 46 strain. Normal growth in the presence of adenine or adenosine was restored in most cases by guanine, guanosine, hypoxanthine, inosine, and inosinic acid. However, for the thymineless mutant strain, guanine and inosine were much less effective in this respect in the presence of adenine, and none of these purines could reverse the inhibitory effect of adenosine. Purine analogs were mostly ineffective in inhibiting or in restoring growth. Our observations indicate that some patterns of purine biosynthesis and utilization in Staphylococcus aureus are different from those already known in other bacterial species. Adenine or adenosine had a greater inhibitory effect on the growth of coagulase-positive strains than on that of the coagulase-negative strain.

Lysozyme Production as an Aid for Identification of Potentially Pathogenic Strains of Staphylococci

Lysozyme production is a frequent property of potentially pathogenic staphylococci. In the present study, 1,186 strains of human origin, 85 strains of animal origin, and 156 strains of Staphylococcus albus (epidermidis) were tested. Of 1,114 coagulase-positive strains of human and animal origin, 1,098 were lysozyme-positive (98.5%). On the other hand, of 157 coagulase-negative strains which, based on further investigations, belong to the potentially pathogenic staphylococci, all were lysozyme-positive. All of the 156 strains (100%) belonging to the species S. albus (epidermidis) were lysozyme-negative. We conclude that lysozyme production is a better index of potentially pathogenic staphylococci than the measurement of free coagulase, especially in cases of strains of animal origin. It is possible that lysozyme production allows a differentiation between pathogenic and nonpathogenic coagulase-negative staphylococci.

Methicillin-resistant Staphylococcus aureus. Antimicrobial susceptibility.

THE number of patients with infections caused by methicillin-resistant, coagulase-positive strains of Staphylococcus aureus in Europe has increased,1 2 3 and the recent detection of similar strains in Seattle,4 , 5 Chapel Hill, North Carolina, Columbia, South Carolina, Houston, Texas, and New York City indicates that such resistant strains may become as prevalent in this country as they are elsewhere. These strains are usually resistant to penicillin, methicillin, erythromycin, chloramphenicol, tetracycline and kanamycin, and patients infected often die in spite of antibiotic treatment.3 Bulger,5 who found in vitro synergism by kanamycin and cephalothin against 9 strains of Staph. aureus that were resistant to methicillin, . . .

Bacterial Interference: A Warning

Colonization of humans with bacteria of low virulency to protect them against infection by a more virulent strain has occasionally been used in nurseries or to control recurrent disease in families. Therapeutic use of bacterial interference is not always successful, however. Investigators at the Communicable Disease Center, Atlanta, sought to use 502A<i>Staphylococcus</i>, a coagulase-positive strain of low

Production of lysozyme by staphylococci and its correlation with three other extracellular substances.

Jay, James M. (Wayne State University, Detroit, Mich.). Production of lysozyme by staphylococci and its correlation with three other extracellular substances. J. Bacteriol. 91:1804-1810. 1966.-Lysozyme production was determined on plates containing 1 mg/ml of Lysozyme Substrate in Heart Infusion Agar with incubation at 37 C for 48 hr. Its production was compared with that of alpha-hemolysin and sheep hemolysin and egg-yolk precipitation, by use of both coagulase-positive and coagulase-negative strains of staphylococci. Of 126 coagulase-positive strains tested, 120 or 95.2% produced lysozyme, 117 or 92.9% produced alpha-hemolysin, 108 or 85.7% precipitated egg yolk, and 102 or 81% produced sheep hemolysin. Of the 49 coagulase-negative strains (which included 22 pathogens), only 4 or 8.1% produced lysozyme, 14 or 28.6% produced alpha-hemolysin, 13 or 26.5% produced sheep hemolysins, and 5 or 10.2% precipitated egg yolk. Only two of the six coagulase-positive strains which failed to produce lysozyme showed any consistent patterns in relation to the four characteristics determined. The four coagulase-negative strains which produced lysozyme were inconsistent for the other characteristics measured. It is suggested that lysozyme production is more a property of coagulase-positive staphylococci, and therefore a better ancillary test of pathogenicity, than either production of alpha-hemolysin or egg-yolk precipitation, because the incidence of lysozyme producers is higher among this group than among those producing the other substances and because fewer coagulase-negative staphylococci produced lysozyme than hemolysins or egg-yolk precipitation. Of 16 other species of bacteria and yeasts tested, all were found negative except Bacillus subtilis. Lysozyme production by staphylococci in heavily contaminated foods was not inhibited on plates containing sodium azide, whereas media containing 7.5% salt and sorbic acid were unsuitable. The possible relationship of lysozyme production to staphylococcal pathogenicity is discussed.

STAPHYLOCOCCUS AUREUS STRAINS ASSOCIATED WITH THE HEDGEHOG, ERINACEUS EUROPAEUS.

1. Strains ofStaphylococcus aureuswere obtained from the nostrils of twenty-three of fifty-eight hedgehogs; the skin of thirty-eight of fifty-six hedgehogs; the paws of thirty-six of fifty-seven hedgehogs and the anus of six of eleven hedgehogs.2. Of 118 strains, 106 (90%) were typable with human staphylophages. Seventeen were phage group I, three phage group II, twenty-five phage group III, sixty-one were typable but unclassifiable into groups, and twelve were untypable.3. Male hedgehogs were more heavily infected than females, while all ages of hedgehogs appeared equally susceptible to infection.4. Of the 124 coagulase positive strains obtained, 107 (86·3%) were resistant to penicillin. Resistance to other antibiotics—chloramphenicol, streptomycin, tetracycline, erythromycin, celbenin—was not encountered.5. Thirty-three (83%) of forty strains produced β-lysin.6. Mites (Caparinia tripilis) and fungi (Trichophyton mentagrophytesvar.erinacei) did not appear to directly influence the carriage ofStaphylococcus aureuson the hedgehog skin.

COMPARATIVE EVALUATION OF FIVE SELECTIVE AND DIFFERENTIAL MEDIA FOR THE DETECTION AND ENUMERATION OF COAGULASE-POSITIVE STAPHYLOCOCCI IN FOODS.

Five selective media for the detection and enumeration of coagulase-positive staphylococci were evaluated for their efficiency in the recovery of 17 strains of coagulase-positive staphylococci from foods. They were Staphylococcus Medium 110 (SM-110), tellurite-glycine-agar (TGA), egg-tellurite-glycine-pyruvate-agar (ETGPA), tellurite-egg-agar (TEA), and tellurite-polymyxin-egg yolk-agar (TPEY). Statistical analysis by the rank correlation method of the efficiency with which these media recovered staphylococci from pure 24-hr Brain Heart Infusion cultures revealed the following efficiencies in descending order: (i) TPEY, (ii) ETGPA, (iii) TGA, (iv) TEA, (v) SM-110. Growth of 17 strains of coagulase-negative cocci on these media showed the following approximate descending order of inhibition to these organisms: (i) ETGPA, (ii) TEA, (iii) SM-110, (iv) TGA, (v) TPEY. The appearance of colonies of the various coagulase-negative strains on each medium was studied for the degree to which they could be confused with colonies of coagulase-positive strains. Nineteen food contaminants, including Proteus vulgaris, Bacillus sp., Escherichia coli, Erwinia sp., fecal streptococci, and others, were also studied for similarities in appearance to staphylococci and for ability to grow on the selective media. The influence of five sterile food homogenates (frozen chicken and tuna pies, custard, smoked ham, and raw whole egg) on recovery of 1,500 enterotoxigenic staphylococci (three strains) per milliliter was determined by statistical analysis. Three main effects (culture, media, and food) and three interactions (media with food, food with cultures, and media with culture) were found to be significant. Recovery on TPEY was influenced less by food than the other selective media and showed optimal recovery ability from sterile custard, eggs, and ham. TGA recovered well from sterile chicken pie and custard, SM-110 from sterile custard, and TEA from sterile ham. None of the media was outstanding in recovering staphylococci from tuna pie. The ability of the five selective media to recover 1,500 enterotoxigenic staphylococci (three strains) per ml from three sterile foods in the presence of 10 strains of contaminating bacteria added at the 0, 10(5), and 10(6) levels per milliliter was also studied and analyzed statistically. Only three factors were significant under these conditions-cultures, foods, and the interaction of media with the level of added contamination. Efficiency of recovery of TGA, SM-110, and ETGPA was found not to be dependent upon the level of contamination. Recovery on TPEY decreased with increases in the number of contaminants. TEA increased in efficiency at the 10(5) level, but decreased at the 10(6) level. When recovery on Trypticase Soy Agar was considered to be 100%, the average percentage of recovery by each of the selective media under all experimental conditions was determined.

Comparative Evaluation of Five Selective and Differential Media for the Detection and Enumeration of Coagulase-Positive Staphylococci in Foods

Five selective media for the detection and enumeration of coagulase-positive staphylococci were evaluated for their efficiency in the recovery of 17 strains of coagulase-positive staphylococci from foods. They were Staphylococcus Medium 110 (SM-110), tellurite-glycine-agar (TGA), egg-tellurite-glycine-pyruvate-agar (ETGPA), tellurite-egg-agar (TEA), and tellurite-polymyxin-egg yolk-agar (TPEY). Statistical analysis by the rank correlation method of the efficiency with which these media recovered staphylococci from pure 24-hr Brain Heart Infusion cultures revealed the following efficiencies in descending order: (i) TPEY, (ii) ETGPA, (iii) TGA, (iv) TEA, (v) SM-110. Growth of 17 strains of coagulase-negative cocci on these media showed the following approximate descending order of inhibition to these organisms: (i) ETGPA, (ii) TEA, (iii) SM-110, (iv) TGA, (v) TPEY. The appearance of colonies of the various coagulase-negative strains on each medium was studied for the degree to which they could be confused with colonies of coagulase-positive strains. Nineteen food contaminants, including Proteus vulgaris, Bacillus sp., Escherichia coli, Erwinia sp., fecal streptococci, and others, were also studied for similarities in appearance to staphylococci and for ability to grow on the selective media. The influence of five sterile food homogenates (frozen chicken and tuna pies, custard, smoked ham, and raw whole egg) on recovery of 1,500 enterotoxigenic staphylococci (three strains) per milliliter was determined by statistical analysis. Three main effects (culture, media, and food) and three interactions (media with food, food with cultures, and media with culture) were found to be significant. Recovery on TPEY was influenced less by food than the other selective media and showed optimal recovery ability from sterile custard, eggs, and ham. TGA recovered well from sterile chicken pie and custard, SM-110 from sterile custard, and TEA from sterile ham. None of the media was outstanding in recovering staphylococci from tuna pie. The ability of the five selective media to recover 1,500 enterotoxigenic staphylococci (three strains) per ml from three sterile foods in the presence of 10 strains of contaminating bacteria added at the 0, 10(5), and 10(6) levels per milliliter was also studied and analyzed statistically. Only three factors were significant under these conditions-cultures, foods, and the interaction of media with the level of added contamination. Efficiency of recovery of TGA, SM-110, and ETGPA was found not to be dependent upon the level of contamination. Recovery on TPEY decreased with increases in the number of contaminants. TEA increased in efficiency at the 10(5) level, but decreased at the 10(6) level. When recovery on Trypticase Soy Agar was considered to be 100%, the average percentage of recovery by each of the selective media under all experimental conditions was determined.

SEPTICEMIA IN INFANTS AND CHILDREN

Four thousand twenty-one consecutive blood cultures obtained from infants and children during the period 1956 through 1962 were analyzed. Two hundred eighty-four (7.1%) of these were positive, representing 198 patients with clinical evidence of septicemia. The over-all mortality rate was 30%. Approximately one-fourth of the patients were newborn babies, with 38% mortality rate; while another one-fourth were children with a chronic underlying disease, with 53% mortality rate. Of the microorganisms identified in the blood cultures, staphylococci, the enteric bacteria, D. pneumoniae and H. influenzae were found in greatest numbers. In children with chronic disease, the enteric bacteria (63% mortality rate) and staphylococci (70% mortality rate) were most common. In previously well children, D. pneumoniae (17% mortality rate), H. influenzae (9% mortality rate) and staphylococci (17% mortality rate) were the most frequent. During the first year of life, staphylococci —coagulase-negative as well as coagulasepositive strains—and the enteric bacteria dominated the neonatal period, while D. pneumoniae and H. influenzae were most prominent after the first month. The over-all mortality rate of patients with septicemia rose significantly over the 7 years of this study. The reasons for this are discussed.

Studies of Staphylococci of Canine Origin with Particular Reference to the Nature and Distribution of their Haemolysins

Staphylococci associated with disease conditions of dogs differ from human and other animal strains in that they seldom form aureus pigment or appreciable amounts of α-toxin. The present findings stress the suitability of rabbit plasma for detecting coagulase activity in dog strains and confirm the close relationship between δ-lysin production and pathogenicity. Among pathogenic dog staphylococci the most frequent haemolytic pattern appears to be βδ whereas in human and other animal pathogens the commonest are αδ and aβδ, respectively. Some 15 per cent of coagulase-positive dog strains produce an unusual haemolysin that differs significantly from staphylococcal a,β,γ,δ and e-lysins. Sheep blood-agar plates containing the diffusible products of Corynebacterium ovis or C. haemolyticum are especially useful for distinguishing between the δ-lysin of coagulase-positive staphylococci and the e-lysin of coagulase-negative strains.

IDENTIFICATION OF THE BACTERIOSTATIC COMPONENT OF 'SCOTCH' BRAND OF CELLULOSE ADHESIVE TAPE.

WE have recently shown that the ‘Scotch’ brand of cellulose adhesive tape of the Minnesota Mining and Manufacturing (Australia) Pty., Ltd., contains a volatile component the antibacterial activity of which is virtually restricted to coagulase-positive strains of Staphylococcus aureus1. In view of this unusual specificity it seemed important to identify the active agent.