A DNA-probe for the detection of the species Staphylococcus haemolyticus.

A 1.3-kb DNA fragment isolated from Staphylococcus haemolyticus strain DSM 20264 can be used as a specific probe for this species. The probe hybridized with 39 clinical isolates of S. haemolyticus but not with any of the 121 isolates representative of the other 25 species of staphylococci described to date.

Comparative analysis of a biofilm-forming Staphylococcus epidermidis strain and its adhesion-positive, accumulation-negative mutant M7.

We have isolated a stable slime-negative mutant, M7, from the wild-type Staphylococcus epidermidis RP62A by mitomycin mutagenesis. Besides its inability to produce slime in the test tube this mutant differed also in two other properties from its parent strain: it lacked the ability to accumulate on a surface, and it did not produce a 115 kDa and a 18 kDa extracellular protein. In all other tested properties such as initial adherence, growth rate, cell-wall composition, surface characteristics, DNA restriction profile, the presence of a 29 kb antibiotic resistance plasmid, and antimicrobial susceptibility profile, M7 was indistinguishable from its wild-type. The mutant is an important basis for further study of the pathogenesis of polymer-associated S. epidermidis infections.

Lack of evidence for increased adherent growth in broth or human serum of clinically significant coagulase-negative staphylococci.

The relevance of adherent growth of coagulase-negative staphylococci (CNS) in vitro to their clinical significance is controversial. We have investigated the accumulation on polymer surfaces of clinically significant CNS strains, isolated from blood cultures and intravascular catheter tips, compared with controls. The adherent growth of significant CNS isolates in a microtitre tray assay was not greater than controls, and this finding was repeated when different combinations of target polymer surface, culture medium and incubation atmosphere type were investigated. The surface accumulation of CNS cultured in pooled human serum was poor compared with culture in broth. Whole cell and surface protein profiles of serum grown Staphylococcus epidermidis differed markedly from broth cultured cells. We recommend the use of human body fluids, such as serum, as useful culture media to assess whether potential virulence determinants are likely to be expressed in vivo. The microtitre tray assay of adherent growth is not helpful in determining the virulence of individual CNS isolates.

Late onset endophthalmitis associated with intraocular lens: a case of molecularly proved S. epidermidis aetiology.

A case of severe endophthalmitis after cataract extraction followed by posterior chamber lens implantation is reported. Microbiological cultures from a tap of the patient's aqueous humour prior to lens explantation as well as from the explanted lens and aqueous and vitreous humour during operation yielded Staphylococcus epidermidis sensu stricto. Scanning electron microscopy showed massive colonisation of the lens loop by staphylococci. Clonal identity of all isolates was demonstrated by plasmid DNA analysis and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of extra-cellular products. This is strongly suggestive of the aetiological role of S. epidermidis in this case of late onset endophthalmitis.

Cell surface hydrophobicity of Klebsiella strains.

On 14 encapsulated Klebsiella strains with different K-antigens and their non-encapsulated mutants the type of fimbriae present and the grade of hydrophobicity of their cell surface (expressed as SAT-value) were investigated. It could be demonstrated that clear correlations exist between the fimbriation of Klebsiella bacteria and their cell surface hydrophobicity. On the other hand, the presence of capsules and the type of K-antigen showed no influence on the degree of hydrophobicity.

New aspects in the pathogenesis and prevention of polymer-associated foreign-body infections caused by coagulase-negative staphylococci.

The significance of polymer-associated infections caused by coagulase-negative staphylococci is discussed. The aspects of bacterial adhesion to polymeric materials as the first important pathogenetic step in the development of such infections are treated. The role of extracellular slime substance (ESS) produced by the bacteria in the pathogenesis is elucidated and newer results concerning the interference of ESS with host defense mechanisms and antibiotic therapy are presented. As an approach to the prevention of polymer-associated foreign-body infections, the modification of the polymeric materials is introduced. Results of recent studies to achieve antiadhesive materials by radiation modification of polymers as well as the development of antimicrobial surfaces by incorporating or bonding antibiotics to polymers are presented.

Inhibition by immunoglobulins of Staphylococcus aureus adherence to fibronectin-coated foreign surfaces.

Recent data suggest that fibronectin may favor Staphylococcus aureus infection by promoting attachment to either injured tissues or implanted foreign bodies. Using a previously described in vitro assay, we show that promotion of S. aureus adherence by surface-bound fibronectin, adsorbed on polymethylmethacrylate (PMMA) coverslips, is antagonized by antistaphylococcal antibodies present in immunoglobulin G (IgG) purified from human plasma. Among the different organisms tested, the protein A-deficient strain Wood 46 of S. aureus was the most strongly inhibited by purified IgG or whole serum dose-dependently. Bacterial adherence was not influenced by preincubating fibronectin-coated PMMA with either purified IgG or whole serum. However, inhibition of bacterial adherence was directly related to the extent of IgG binding to S. aureus Wood 46. When F(ab')2 fragments of purified IgG were tested in the adherence assay, they could also reduce the interaction between S. aureus Wood 46 and fibronectin-coated PMMA. Two other staphylococcal strains were also tested in the adherence inhibition assay: Whereas the protein A-rich strain Cowan I of S. aureus was moderately inhibited by purified IgG or whole serum, S. epidermidis KH 11 was not at all inhibited by IgG which bound poorly to the bacterial cells. This study has demonstrated that bacterial coating by humoral factors, and specifically IgG, may influence significantly subsequent adherence of S. aureus to surface-bound fibronectin.

Antimicrobial activity of polymers coated with iodine-complexed polyvinylpyrrolidone.

Polymer-associated infection is a problem of increasing importance in modern medicine. In a new approach to prevent such infections we have modified polyvinylfluoride (TEDLAR) films by graft copolymerization with N-vinylpyrrolidone to which iodine can be complexed. Grafting reaction was performed by the preirradiation technique using an electron accelerator. Grafted films were then treated in Lugol's solution for at least 24 h. Release of free iodine from the films was determined either by titration or using the agar disc diffusion test, showing an iodine release for up to 4-5 days. The antimicrobial activity of the films was tested in bacterial adhesion measurements. Bacterial and fungal cells in the range of 10(3) to 10(6) cfu/cm2 polymer were found on control samples without iodine, whereas on iodine-complexed films no viable cells could be detected at least for 5 days or even longer. Thus, microbial adhesion and growth can be inhibited by iodine-containing polymers.

[A molecular biology approach to the species identification of coagulase-negative staphylococci]. / Molekuliarno-biologicheskii podkhod k vidovoi identifikatsii koagulazo-otritsatel'nykh stafilokokkov.

A 1.3 DNA fragment isolated from Staphylococcus haemolyticus strain DSM 20264 can be used as a specific probe for this species. 28 collection strains including type strains of 26 Staphylococcus species, as well as 135 clinical isolates representing 8 species, have been studied with this probe by the dot hybridization method. The probe has been found to hybridize with all 42 S. haemolyticus strains, but with none of 121 strains belonging to other Staphylococcus species.

In-vitro activity of three fluoroquinolones, cefotaxime and clindamycin against staphylococci.

The in-vitro activity of three fluoroquinolones (ciprofloxacin, ofloxacin, temafloxacin) against 200 well-defined clinical isolates of staphylococci was investigated. The in-vitro activity of the fluoroquinolones tested was equal, with a strong indication of cross resistance. A clear distribution over two populations of different quinolone susceptibility--"naturally susceptible" and "naturally resistant" strains--could be found in penicillin-resistant, methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus haemolyticus.

Typing of coagulase-negative staphylococci isolated from foreign body infections.

Twenty-six coagulase-negative staphylococci isolated from patients with various foreign body infections were characterised using different typing systems. Staphylococcus epidermidis was the most predominant species found. Phage typability was below 50% in all strains. The strains showed differences in surface properties--relative hydrophobicity or hydrophilicity--and ability to adhere to polystyrene with subsequent slime production (adherence tube test). Protein and polypeptide profiles as well as plasmid profiles demonstrated the heterogeneity of the strains. Thus, this preliminary study indicates that all coagulase-negative staphylococci of human origin may become involved in foreign body infections.

The role of capsule as a barrier to bacteriophage adsorption in an encapsulated Staphylococcus simulans strain.

The polyvalent staphylococcal bacteriophage U16 failed to adsorb to an encapsulated Staphylococcus simulans strain. Partially purified cell wall and teichoic acid of this strain could, however, inactivate bacteriophage U16 to a great extent, indicating the presence of the phage receptor. It is concluded that the capsule of Staphylococcus simulans acts as a barrier for the interaction of the phage with its receptor in the bacterial cell wall.

Cell wall structure of coagulase-negative staphylococci and its relation to adsorption of phages.

The coagulase-negative staphylococcal species S. xylosus and S. saprophyticus are able to inactivate phages of the International Basic Set for S. aureus. The cell wall teichoic acids of these species contained two polyols: glycerol and ribitol. Removal of ribitol teichoic acid resulted in a parallel decrease in the ability of the cell walls to inactivate the phages.

The phage adsorption test: a simple method for differentiation between staphylococci and micrococci.

A simple phage adsorption test is recommended for differentiation between staphylococci and micrococci. All 132 strains of Staphylococcus tested inactivated phage U16 significantly, whereas of 123 strains of Micrococcus tested, only three strains of Micrococcus candicans were able to adsorb this staphylococcal phage. There are special problems in the taxonomy of M. candicans.

Evidence for degradation of synthetic polyurethanes by Staphylococcus epidermidis.

The survival of Staphylococcus epidermidis strain KH 11 in the presence of synthetic high molecular polyurethanes was prolonged in comparison to control experiments performed in the absence of any nutrients. Investigations of the bacteria after contact with the polymers revealed changes in their surface properties and metabolism, in particular a marked induction of urease activity. ESCA (Electron Spectroscopy for Chemical Analysis) measurements detected a decrease in elementary nitrogen in the polyurethane surfaces after incubation with the bacteria. The alterations observed indicate an urease-induced degradation of synthetic polymers by Staphylococcus epidermidis KH 11.

[Infections caused by coagulase-negative Staphylococci in immunocompromised patients]. / Infektionen durch koagulasenegative Staphylokokken bei abwehrgeschwächten Patienten.

Coagulase-negative staphylococci are important members of the normal aerobic microflora of human skin and mucous membranes. Normally they are not pathogenic for men. But the increase in patients with implanted plastic foreign bodies or intravascular catheters had led to a dramatic change. In these patients, coagulase-negative staphylococci are the predominant organisms causing septicemia. Special pathomechanisms are involved in the colonization of polymers by staphylococci leading to a "plastic infection". Intravascular catheters are also important factors in the origin of septicemia in premature neonates and in patients with malignant diseases, especially under cytostatic therapy. Premature or suppressed opsonophagocytosis mechanisms are responsible for the origin and maintainance of septicemia.

Detection of staphylococcal enterotoxin B and toxic shock syndrome toxin: PCR versus conventional methods.

An equal accuracy of commercially available kits, i.e., the reverse passive latex agglutination test (RPLA-Oxoid) and the Enzyme-Linked Immunosorbent Assay (SET-EIA Riedel Haen, Germany) to identify the presence of the staphylococcal enterotoxin B and the toxic shock syndrome toxin TSST-1 as well as the PCR-technique to detect the presence of the seb and tst-genes was demonstrated in 18 Staphylococcus aureus isolates. Selection of a primer pair from the etb gene sequence allowing simultaneously detection of the etb and tst-genes in S. aureus using a rapid DNA extraction method is emphasized.

Susceptibility of staphylococci and enterococci to glycopeptides comparison of 3 test methods.

The significance of grampositive bacteria, especially staphylococci and enterococci, as nosocomial pathogens has increased in the last decade. Furthermore, resistance to commonly used antibiotics like beta-lactams has also become more common and even resistance to glycopeptides has been observed. We evaluated the susceptibility of 150 staphylococcal clinical isolates (52 S. epidermidis, 52 S. haemolyticus, 10 S. saprophyticus, 10 S. hominis, 4 S. warneri, 4 S. simulans, 4 S. capitis and 14 S. aureus) and of 50 enterococci (49 E. faecalis, 1 E. faecium) to the glycopeptides, vancomycin and teicoplanin. The data from the agar dilution test used as reference method were compared with the results from the E test and the agar disk diffusion test. Concerning vancomycin, no resistance among all the staphylococcal isolates was observed whereas one single enterococcal strain (E. faecium) proved to be resistant. The overall resistance of staphylococcal isolates against teicoplanin was about 10.7% (15 S. haemolyticus, 1 S. epidermidis) being mainly due to the high proportion of S. haemolyticus strains (52 out of 150) among the staphylococcal isolates. Teicoplanin resistance among the enterococci was not detected. For vancomycin, a very close correlation between the MICs from the agar dilution test and the E test was noticed. As concerns teicoplanin, the MICs from the E-test were usually somewhat lower than those obtained by the agar dilution test. No correlation was found between the MICs of resistant and intermediate staphylococcal strains and the results from the teicoplanin agar disk diffusion test. For routine teicoplanin susceptibility testing of staphylococci, the determination of the MIC (e.g., by the E test) is much more reliable for detecting resistant strains than the agar disk diffusion test.

[Comparison of activity of fosfomycin, oxacillin and penicillin G against staphylococci and micrococci (author's transl)]. / Vergleich der Staphylokokken- und Mikrokokken-Wirksamkeit von Fosfomycin, Oxacillin und Penicillin G.

The in vitro sensitivity against fosfomycin, oxacillin and penicillin G was tested in 65 Staphylococcus aureus strains, 71 coagulase negative staphylococci and 46 micrococci. Fosfomycin was very effective against staphylococci. Cross resistance with simultaneously tested penicillins could not be demonstrated. Fosfomycin was only partially effective against micrococci for which penicillin G was most effective.

Cell wall analysis and taxonomy of staphylococci.

50 representative staphylococcal strains were selected from 18 clusters of a previous numerical taxonomy study (2). The types of peptidoglycan and teichoic acid were investigated in these strains. The results of this cell wall analysis were compared with the data of the numerical taxonomy study (2) and the Kloos and Schleifer-classification system.