Temporal study of the staphylococci and micrococci of normal infant skin

Staphylococcus and Micrococcus populations were collected from the healthy skin of 10 infant subjects. Infants were sampled from 1 day to 32 weeks of age. Species were characterized by approximately 30 different morphological, physiological, and biochemical characters. Staphylococci were the predominant inhabitants of normal skin, whereas micrococci were found only occasionally in this environment. Staphylococcus epidermidid, S. haemolyticus, and S. hominis were the predominant and persistent staphylococci. These species constituted a high percentage of the total aerobic bacterial flora of infant skin. Micrococcus luteus and M. kristinae were the prevalent micrococci found on infant skin. Only limited correlation between Staphyloccus and Micrococcus populations and infant age or body area sampled was indicated by this study.     

Preliminary studies on the characterization and distribution of Staphylococcus and Micrococcus species on animal skin.

A total of 221 strains of staphylococci and 98 strains of micrococci isolated from the skins of Eastern gray squirrels, Southern flying squirrels, raccoons, opossums, squirrel monkeys, swine, sheep, horses, cattle, and dogs were characterized in a preliminary attempt to resolve their natural relationships and distribution in nature. Staphylococci demonstrating the widest host range included Staphylococcus xylosus and unnamed Staphylococcus sp. 3. Unnamed Staphylococcus sp. 2 was isolated only from sheep, Staphylococcus sp. 4 only from opossums, Staphylococcus sp. 5 only from squirrel monkeys, and Staphylococcus sp. 6 only from swine. The predominant species isolated from human skin, including S. epidermidis, S. hominis, S. haemolyticus, and S. capitis, were either not isolated or only rarely isolated from animal skin. Micrococcus varians was the predominant Micrococcus species isolated from animal skin. M. luteus was only occasionally isolated. M. lylae, M. sedentarius, M. roseus, M. kristinae, and M. nishinomiyaensis, species occasionally isolated from human skin, were not isolated from animal skin.     

The Tellurite Reactions of Coagulase Negative Staphylococci and Micrococci

S ummary . Methods for determining the tellurite reactions of coagulase negative staphylococci and micrococci have been applied to strains causing urinary tract infections in human patients. The tellurite positive strains were assigned to Micrococcus subgroup 3 and Staphylococcus subgroup VI of the Baird-Parker (1963) classification.     

Characterization of micrococcaceae isolated from salt used for Spanish dry-cured ham

The microbial flora of salt used in the production of Spanish dry-cured ham was studied. The results indicated that Micrococcaceae constituted the predominant flora. Identification of the 369 isolates belonging to the family Micrococcaceae revealed that 60% belonged to genus Staphylococcus, 25% to Micrococcus, 6% to Kocuria, 5.4% to Dermacoccus and 0.5% to Stomatococcus. The species most often isolated was Staph. xylosus (28.9%), followed by M. lylae (21.4%), Staph. equorum (18.55%) and D. nishinomiyaensis (5.4%). The results indicate that the salt during salting process of dry-cured hams offers an ecosystem suitable for the survival of the staphylococci and micrococci.     

Deoxyribonucleic acid base composition and taxonomy of violet-pigmented cocci

The content of guanine and cytosine in DNA of the violet-pigmented micrococci designated asStaphylococcus flavocyaneus andMicrococcus flavocyaneus varies within the range of 70.8 – 72.0%. These species have similar deoxyribonucleic acid base compositions and do not differ physiologically and morphologically: they both produce yellow and violet pigments, hydrolyse gelatin and casein, reduce nitrates and do not form lipase. Therefore we consider them in accordance with Kocur and Martinec (1962, 1963) identical. They do not, however, seem to be identical withMicrococcus luteus (Schroeter, 1872) Cohn 1872 because the content of guanine and cytosine in DNA of the neotype culture of this species was found to be 66.3%.Micrococcus luteus differs from the violet pigmented micrococci also physiologically. It does not produce violet pigment, does not hydrolyse gelatin and casein and does not produce urease. For the violet pigmented strainMicrococcus cyaneus the use of the original designation is recommended:Micrococcus cyaneus (Schroeter) Cohn 1872, as it differs from the other violet cocci not only physiologically — it does not produce yellow pigment, oxidises mannitol, dulcitol and sorbitol, produces lipase and does not hydrolyse casein — but also in its DNA base composition.     

Novobiocin Resistance and the Classification of Staphylococci and Micrococci

S ummary . Isolates of staphylococci and micrococci, 105 in all, classified according to Baird-Parker's classification (Baird-Parker, 1963,1965) were examined for their sensitivity to novobiocin. All of the staphylococci were sensitive to novobiocin as also were strains of Micrococcus luteus and M. roseus. Almost all strains belonging to Micrococcus subgroups 1–6 were resistant to novobiocin.     

The Genetic Structure of Staphylococcus aureus Populations from the Southwest Pacific

The genetic structure of Staphylococcus aureus populations sampled from diverse regions of the globe have been the subject of numerous investigations. Here we describe the structure of S. aureus populations collected from the Southwest Pacific. Multi-locus sequence typing was performed on 467 isolates obtained from people with nasal colonization or bacteremia in Auckland (NZ), and patients predominantly affected by skin and soft tissue infection in Samoa, Fiji and Tonga. The predominant sequence types (STs) varied between Auckland (ST5), Fiji (ST30), and Samoa (ST1), however, the overall genetic diversity within each region did not differ significantly between locations. Divergent Clonal Complex 75 (CC75) strains were isolated in Auckland and Fiji. When diversity of the Southwest Pacific populations was compared with those previously described from Asia, Europe, North America and Africa no significant differences were detected. With the exception of CC75 strains, the global collection of S. aureus encompasses relatively little diversity, with novel STs arising locally from a small number of widespread lineages.     

A phylogenetic analysis of staphylococci, Peptococcus saccharolyticus and Micrococcus mucilaginosus

The intra- and intergeneric relationships of the genus Staphylococcus, and the phylogenetic position of Peptococcus saccharolyticus and Micrococcus (Staphylococcus salivarius), were investigated by comparative oligonucleotide cataloguing of 16S rRNA. All the staphylococci investigated form a phylogenetically coherent group at the genus level that, in addition, contains the anaerobic species Peptococcus saccharolyticus. The genus Staphylococcus belongs to the broad Bacillus-Lactobacillus-Streptococcus cluster that is defined by Gram-positive bacteria with a low DNA G+C content. Micrococcus mucilaginosus is not a genuine member of the genus Micrococcus. The binary matching coefficients between the 16S rRNA of Micrococcus mucilaginosus and those representatives of the Arthrobacter/Micrococcus group and related genera indicate that Micrococcus mucilaginosus should be regarded as a member of a new genus.     

Amino acid sequence of the murein of Planococcus and other Micrococcaceae

The amino acid composition and amino acid sequence of the murein (peptidoglycan) of 10 strains of planococci were studied. It is shown that the peptide subunit consists of muramyl-l-alanyl-gamma-d-glutamyl-l-lysyl-d -alanine. The cross-linking of two adjacent peptide subunits is mediated by d-glutamic acid which is bound to the epsilon-amino group of lysine by its gamma-carboxyl group and to the carboxyl group of d-alanine of an adjacent peptide subunit by its amino group. About 20 to 25% of the peptide subunits are not cross-linked. The murein structure of the different species and strains of Micrococcus, Staphylococcus, and Sarcina are compared. It is evident that the murein structure is a very good criterion for grouping the micrococci. In addition, some of these groups are fairly well defined by physiological properties as well as by their guanine + cytosine content of the deoxyribonucleic acid e.g., Micrococcus, Staphylococcus, Planococcus, Sarcina ureae. Other groups, represented by a single or a few strains only, such as M. varians NTCC 7281, M. radiodurans, M. freudenreichii ATCC 407, and M. luteus ATCC 398, need further investigation.     

Violagabriellae variant of Staphylococcus epidermidis on normal human skin

Twenty-seven strains of a reddish violet pigment-producing variety of Staphylococcus epidermidis have been recovered from normal human skin. They closely resemble the previously unique Castellani strain, named Micrococcus violagabriellae, which was placed by K. J. Steel in S. epidermidis. These strains are classified as S. epidermidis by using the Baird-Parker schema; however, besides the pigment produced, they also differ from S. epidermidis in proteolytic activity and effect on litmus milk. The variety seems to be part of the normal flora of the human axilla.     

Acetic, propionic, and oleic acid as the possible factors influencing the predominant residence of some species of Propionibacterium and coagulase-negative Staphylococcus on normal human skin

The minimum inhibitory concentration (MIC) of acetic and propionic acid for resident bacteria on normal human skin, such as Propionibacterium acnes and Staphylococcus epidermidis, was 25 mg/mL or more at any pH tested (pH 5.5-6.8). While the MIC of these acids for most of the transient bacteria was markedly decreased by lowering the pH of the media and at pH 5.5, the mean pH value of the normal human skin, the MIC was 6.25 mg/mL or less. The MIC of oleic acid for some strains of Gram-positive transient bacteria of Streptococcus, Micrococcus, or Bacillus was 100 micrograms/mL or less at all pH's tested. Staphylococcus aureus was resistant to this acid at pH 6.8, but became as sensitive as Streptococcus when the pH was lowered. The growth of P. acnes, the most predominant resident bacterium, was enhanced markedly and reached a maximum level at 6.25 mg/mL of propionic acid, 12.5 mg/mL of acetic acid, and 50-100 micrograms/mL of oleic acid. On the basis of these results, we presumed that acetic, propionic, and oleic acids are factors influencing the predominant residence of some species of Propionibacterium and coagulase-negative Staphylococcus on normal human skin.     

Effects of environmental conditions on microbial proteolysis in a pork myofibril model system

P.M. KENNEALLY, N.G. FRANSEN, H. GRAU, E.E. O'NEILL & E.K. ARENDT.1999.A number of bacterial strains used for meat fermentations were screened for proteolytic activity. A strain of Micrococcus which was found to be proteolytic was evaluated for the effects of environmental conditions on its proteolytic activity against pork myofibrillar proteins using response surface methodology. Three strains of micrococci were also tested for the ability to produce free amino acids from pork myofibrils. Analysis of the effects of environmental conditions showed that proteolytic activity would be minimal under conditions normally found in fermented sausages, thereby suggesting that proteolysis in these products is largely due to endogenous meat enzymes. The three strains of micrococci were shown to produce free amino acids from pork myofibrils, thereby demonstrating the presence of peptidase activity in these strains.     

The occurrence and comparative phenotypic characteristics of Staphylococcus spp. from healthy and diseased, household and shelter dogs, based on routine biochemical diagnostic methods

To determine the staphylococcal colonization pattern in healthy and diseased dogs, living in two particular environments, a number of microbiological samples were taken. Overall, twenty dogs, either healthy or with infected skin lesions, were examined. In each case bacterial swabs were collected from the nasal mucosa, ear, perineum, lumbo-sacralis triangle, and from the infection sites if such were present. A total number of 104 isolates representing different staphylococcal species were isolated and identified using routine biochemical methods applied in diagnostic laboratories. Among 17 isolated staphylococcal species, Staphylococcus intermedius was the most common species isolated from both healthy or diseased dogs living either in animal shelter or household environments. The pattern of Staphylococcus sp. colonization differs considerably for animals living in the two tested habitats. In particular, S. aureus MRSA and MSSA isolates were detected only in infected skin lesion samples from animals that dwelled in the animal shelter. As could be expected, S. intermedius was found to be a predominant causative agent in canine skin infections. In our study, we demonstrated that S. intermedius in its carrier-state, inhabits mainly the mucosal membrane of the nasal vestibule. It was also found in the samples taken from the skin, the lumbo-sacralis triangle and perineum, but was rarely isolated from the ears.     

Use of Antibody to Membrane Adenosine Triphosphatase in the Study of Bacterial Relationships

An antiserum to Ca(2+)-activated adenosine triphosphatase from membranes of Micrococcus lysodeikticus cross-reacted in agar gels with membrane adenosine triphosphatases from other pigmented micrococci and related species. Species of Micrococcus and Sarcina showed different levels of inhibition of adenosine triphosphatase activities in heterologous reactions with antiserum. Inter- and intraspecific relationships based on the inhibition reaction were compared with an independent parameter, namely the quantitative and qualitative composition of the bacterial membrane phospholipids and fatty acids. The guanine plus cytosine contents in the deoxyribonucleic acid of the species studied correlated well with the serological cross-reactivity of adenosine triphosphatases from their membranes. The types of cross-bridges found in the peptidoglycans of these cocci were also compared with the other properties. The results suggest that an antiserum specific for a major membrane protein may be a reliable and most useful adjunct in studying bacterial serotaxonomy.     

Nuclease Production and Lysostaphin Susceptibility of Staphylococcus aureus and Other Catalase-Positive Cocci

Some strains of Staphylococcus epidermidis and Micrococcus sp. produce nucleases. However, thermal stability was shown to be unique to the nucleases of S. aureus. In addition, two micromethods for susceptibility testing to lysostaphin were more precise and convenient than anaerobic glucose fermentation in distinguishing between the genera Staphylococcus and Micrococcus.     

Identification of Micrococcaceae in Clinical Bacteriology

The cellular morphology, identifying physiological characteristics, and a key to the human genera of Micrococcaceae are presented with flow charts for identification of aerobic and anaerobic isolates. These flow charts can be amended as desired, depending upon the degree of accuracy desired. Micrococcaceae isolates in a 350-bed private general hospital during a 15-week period are tabulated to show relative numbers of the different genera and species, with their probable relationship to infection or contamination. Only 11 of the 220 Micrococcaceae isolates were not Staphylococcus; no Sarcina or Peptococcus were isolated. Of the Staphylococcus isolates, 61% were S. epidermidis. Almost 18% of the S. aureus isolates were coagulase-negative. Of the S. aureus isolates, 80% of the coagulase-positive isolates were infecting agents, as were 67% of the coagulase-negative S. aureus isolates, compared to only 48% of S. epidermidis isolates. Two of four Gaffkya isolates but only one of seven Micrococcus isolates were infecting agents. If coagulase production is used as the sole criterion for speciation of staphylococci, and Micrococcus is not differentiated from Staphylococcus, the term "coagulase-negative staphylococci" does not differentiate three distinct levels of pathogenicity. Coagulase-negative S. aureus is more virulent than S. epidermidis or Gaffkya, which are more virulent than Micrococcus or Sarcina.     

The fine structure of Micrococcus radiophilus and Micrococcus radioproteolyticus

The radiation resistant bacteria Micrococcus radiophilus and M. radioproteolyticus were studied by thin sectioning and freeze-etching techniques and the two species were found to be similar in the fine structure. The only significant difference was in the appearance of the surfaces of the cell walls in freeze-etched preparations.Since the two species, together with M. radiodurans, possess a unique cell wall structure and a cell wall peptidoglycan, which is different from that of other micrococci and Gram-positive cocci, it is recommended that they be reclassified into a new genus.     

Use of Lysostaphin in the Isolation of Highly Polymerized Deoxyribonucleic Acid and in the Taxonomy of Aerobic Micrococcaceae

By use of the staphylolytic enzyme lysostaphin, a method was devised for isolating and purifying highly polymerized deoxyribonucleic acid (DNA) from lysostaphinsusceptible Micrococcaceae. Staphylococcus aureus DNA isolated by this procedure gave an estimated molecular weight of ca. 2 x 10(8) and a residual protein content of 2.3%. The mole percentage of guanine + cytosine (GC) present in the DNA from 21 strains of aerobic Micrococceae was determined by buoyant density in cesium chloride. DNA from 12 biochemically typical members of the genus Staphylococcus gave a mean GC composition of 35.2 +/- 0.5 mole per cent. Four biochemically atypical Staphylococcus strains and one biochemically typical strain of the genus Micrococcus (M. candicans) were found to be susceptible to lysostaphin and gave typical Staphylococcus spp. GC base ratios. One biochemically atypical member of the genus Micrococcus (M. varians) was not susceptible to lysostaphin and gave a typical Micrococcus spp. GC base ratio. Lysostaphin susceptibility is an easy test to perform, and the results of this test appear to correlate with GC base ratio studies of the genera of Micrococcaceae.     

Science of hemolytic activity of some radiation-resistant micrococci in food.

Micrococci resistant to 1 Mrad of gamma radiation were isolated from irradiated chicken. Three isolates were hemolytic on blood agar plates and were selected for further study. Two other radiation-resistant micrococci, Micrococcus radiodurans and Micrococcus radiophilus, were included in the study because there is only a very limited amount of information regarding hemolytic activity of these organisms and their potential role of public health importance. Tests to determine hemolytic patterns, hemolytic activity of extracellular substances, leukocytic activity, presence of enzymes commonly associated with pathogenicity (coagulase, deoxyribonuclease, phosphatase), and pathogenicity for laboratory animals all suggested that the organisms would not be of public health significance.     

Microbiological examination of sebeel water.

Water samples from clay storage jugs ("zeers") located in homes and at public watering stands ("sebeels") at streets, mosques, and schools were examined. Coliforms, fecal coliforms, and fecal streptococci were detected in 100, 69, 88, and 91.56% of the samples, respectively. The general microbiology of the water and some factors affecting microbial load were studied. The predominant bacterial genera of sebeel water were found to be Staphylococcus. Aerococcus, Micrococcus, Streptococcus, Bacillus, Listeria, Lactobacillus, and Arthrobacter. A simple modification of zeer construction was suggested to help improve sanitation.