CORRELATION OF DNA BASE COMPOSITION AND ACID FORMATION FROM GLUCOSE OF STAPHYLOCOCCI AND MICROCOCCI

Comparison of methods for routine separation of coagulase-negative staphylococci from micrococci isolated from sheep

A total of 176 Gram-positive, catalase positive cocci strains, isolated from sheep were studied by different routine tests for the differentiation of staphylococci and micrococci, comparing their validity and usefulness. By glucose fermentation and growth in the anaerobic portion of thioglycolate 85 and 73.6% respectively of coagulase negative staphylococci were misclassified as Micrococcus spp. Susceptibility to lysostaphin was an adequate test for the differentiation of the strains. Atypical results in the production of acid from glycerol/erythromycin were obtained in 11.8% of the coagulase negative strains and 16.7% of micrococci. The combined use of the selective media furazolidone agar and Schleifer and Krämer medium resulted in a fast and useful separation of ovine staphylococci and micrococci. The bacteriolytic activity misclassified 32.2% of the coagulase negative strains.

Carbohydrate dissimilation tests in the identification of staphylococci

Reproducible and comparable results were obtained in different media containing different nutrients and indicators when representative Staphylococcus strains were tested for acid production from carbohydrates. Only in tests with melezitose, ribose and turanose many discrepant, weak or delayed positive reactions occurred. In tests with other carbohydrates similarly many weak results were visible after 1 day of incubation, but acid reactions were clear and easy to read after 2 days in phenol red broth and Andrade peptone water media, commonly used in the routine identification of other bacterial genera. Important alkalinization effects were observed after prolonged incubation, but not after short periods up to 24 h in peptone-rich test media. Growth was poor and numbers of acid reactions from carbohydrate breakdown detected did not increase when peptone-free media were used.

The identification of staphylococci in clinical and food microbiology laboratories

A comprehensive review of the methods which have been utilized for the identification of staphylococci is presented. Biochemical characteristics which have assisted in the primary isolation of staphylococci, such as pigmentation, hemolytic activity, the egg yolk phenomenon, and deoxyribonuclease and coagulase production, are also analyzed. The potential applicability of advanced techniques to identify staphylococci, such as the detection of enterotoxin production, base ratio analysis, cell wall analysis, phage typing, and serology, is discussed. The following procedures are recommended for routine use: Idnetification of Staphylococcus sp. (clinical laboratories): microscopic observation, catalase activity, coagulase production, lysostaphin sensitivity, and (optional) facultative growth in thioglycolate medium. Identification of Staphylococcus aureus (food laboratories): microscopic observation, catalase activity, coagulase production, thermonuclease production, and (optional) lysostaphin sensitivity.

Characterization of Micrococcaceae from the urinary tract

Two hundred and seven urinary strains of staphylococci and micrococci were classified biochemically according to Baird-Parker (1963) and by means of a simplified schema. One hundred and thirteen strains belonged to Staphylococcus aureus, S. epidermids or S. saprophyticus (64 strains) according to the simplified schema, respectively to Baird-Parker's sub-groups SI, SII or M3. S. saprophyticus was isolated from young, female out-patients, was relatively resistant to novobiocin and contained poly AbetaC (beta-N-acetylglucosaminyl ribitol teichoic acid and beta-N-acetylglucosaminyl glycerol teichoic acid). S. aureus and S. epidermidis were isolated from older, male in-patients, were sensitive to novobiocin and contained poly A (N-acetylglucosaminyl ribitol teichoic acid), respectively poly B (glucosyl glycerol teichoic acid). Ninety-four strains belonging to other Staphylococcus or Micrococcus subgroups could not be classified by the simplified schema. With few exceptions, these strains were sensitive to novobiocin and either gave a precipitin reaction corresponding to poly C or were non-typable with the teichoic acid reference systems used. The simplified schema is recommended for the classification of coagulase-negative strains of Micrococcaceae.

Use of shake cultures in a semisolid thioglycolate medium for differentiating staphylococci from micrococci

The standard diagnostic test for differentiating staphylococci from micrococci is based on the ability of the former to produce acid anaerobically in a glucose-containing growth medium. This test has been modified to provide greater convenience, easier interpretation of results, and better correlation with deoxyribonucleic acid (DNA) base composition. In the modified test, shake cultures in Brewer's fluid thioglycolate medium with 0.3% agar added are observed for growth in the anaerobic zone of the tubes. This test was applied to 125 strains of staphylococci and micrococci, and all except two strains gave results that were consistent with other criteria. Of particular interest were eight strains of Micrococcus saprophyticus and three strains of M. lactis that have a DNA composition of 30 to 37% guanine plus cytosine (GC). All 11 of these cultures produced anaerobic growth and thus would be classified as staphylococci. Strains of M. lactis that have a high GC content in their DNA grew only aerobically. Some cultures of staphylococci produced characteristic band patterns of anaerobic growth and other cultures produced only a few anaerobic colonies from an inoculum of 10(6) to 10(7) cells. These observations suggest some interesting genetic and metabolic capabilities in such cultures.

Neutral lipids in the study of relationships of members of the family micrococcaceae

The organisms studied were those of the family Micrococcaceae which cannot participate in genetic exchange with Micrococcus luteus and those whose biochemical and physiological characteristics appear to bridge the genera Staphylococcus and Micrococcus. The hydrocarbon compositions of M. luteus ATCC 4698 and Micrococcus sp. ATCC 398 were shown to be similar to those previously reported for many M. luteus strains, consisting of isomers of branched monoolefins in the range C25 to C31. However, Micrococcus sp. ATCC 398 differed somewhat by having almost all C29 isomers (approximately 88% of the hydrocarbon composition). Micrococcus spp. ATCC 401 and ATCC 146 and M. roseus strains ATCC 412, ATCC 416, and ATCC 516 contained the same type of hydrocarbon patterns, but the predominant hydrocarbons were within a lower distribution range (C23 to C27), similar to Micrococcus sp. ATCC 533 previously reported. The chromatographic profile and carbon range of the hydrocarbons of an atypical strain designated M. candicans ATCC 8456 differed significantly from the hydrocarbon pattern presented above. The hydrocarbons were identified as branched and normal olefins in the range C16 to C22. Studies of several different strains of staphylococci revealed that these organisms do not contain readily detectable amounts of aliphatic hydrocarbons. The members of the family Micrococcaceae have been divided into two major groups based on the presence or absence of hydrocarbons. With the exception of M. candicans ATCC 8456, this division corresponded to the separation of these organisms according to their deoxyribonucleic acid compositions.