Bacteriophage Types and Antibiotic Susceptibility of Staphylococcus aureus

In vitro tests of 132 strains of Staphylococcus aureus, among which were 38 (28.7%) heteroresistant strains, were performed with 14 commonly used antibiotics, including gentamicin and vancomycin. Heteroresistant strains were found predominantly, but not only, with group 3 phage-typable strains; no heteroresistant strain was found in out-patients. Gentamicin appeared as a uniformly effective agent at low concentrations against oxacillin-sensitive and -resistant strains. It is suggested that gentamicin should be compared to vancomycin in future clinical therapeutic trials in severe staphylococcal infections, especially in cases due to oxacillin-resistant strains.     

Transfection of Staphylococcus aureus with Bacteriophage Deoxyribonucleic Acid

Staphylococcus aureus cells of strain 8325 (N) are competent for phage deoxyribonucleic acid (DNA) when harvested in the early exponential growth phase. Phenotypic expression of the competence requires divalent cations, and calcium ions are most effective. Treatment of phage DNA with deoxyribonuclease completely destroys infectivity and heat-denaturated DNA is not infectious. The highest frequency of transfection is around 10(4) plaque-forming units per mug of DNA.     

Combined Use of Bacteriophage K and a Novel Bacteriophage To Reduce Staphylococcus aureus Biofilm Formation

Biofilms are major causes of impairment of wound healing and patient morbidity. One of the most common and aggressive wound pathogens is Staphylococcus aureus, displaying a large repertoire of virulence factors and commonly reduced susceptibility to antibiotics, such as the spread of methicillin-resistant S. aureus (MRSA). Bacteriophages are obligate parasites of bacteria. They multiply intracellularly and lyse their bacterial host, releasing their progeny. We isolated a novel phage, DRA88, which has a broad host range among S. aureus bacteria. Morphologically, the phage belongs to the Myoviridae family and comprises a large double-stranded DNA (dsDNA) genome of 141,907 bp. DRA88 was mixed with phage K to produce a high-titer mixture that showed strong lytic activity against a wide range of S. aureus isolates, including representatives of the major international MRSA clones and coagulase-negative Staphylococcus. Its efficacy was assessed both in planktonic cultures and when treating established biofilms produced by three different biofilm-producing S. aureus isolates. A significant reduction of biofilm biomass over 48 h of treatment was recorded in all cases. The phage mixture may form the basis of an effective treatment for infections caused by S. aureus biofilms.     

Complete Genome Sequence of Staphylococcus aureus Bacteriophage GH15

GH15 is a polyvalent phage that shows activity against a wide range of Staphylococcus aureus strains. In this work, the complete genome sequence of GH15 was determined. With a genome size of 139,806 bp (double-stranded DNA), GH15 is the largest staphylococcal phage sequenced to date. The complete genome encodes 214 open reading frames (ORFs) and 4 tRNAs. The closest relatives are the class III staphylococcal myobacteriophages, including K, A5W, ISP, Sb-1, and G1. Interestingly, although corresponding gene sequences demonstrate very high similarity, all the introns and inteins present in the phages listed above are absent in GH15. As such, GH15 can be considered phylogenetically unique among the staphylococcal myobacteriophages, indicating the diversity of this family.     

Mobilization of Genomic Islands of Staphylococcus aureus by Temperate Bacteriophage

The virulence of Staphylococcus aureus, in both human and animal hosts, is largely influenced by the acquisition of mobile genetic elements (MGEs). Most S. aureus strains carry a variety of MGEs, including three genomic islands (νSaα, νSaβ, νSaγ) that are diverse in virulence gene content but conserved within strain lineages. Although the mobilization of pathogenicity islands, phages and plasmids has been well studied, the mobilization of genomic islands is poorly understood. We previously demonstrated the mobilization of νSaβ by the adjacent temperate bacteriophage ϕSaBov from strain RF122. In this study, we demonstrate that ϕSaBov mediates the mobilization of νSaα and νSaγ, which are located remotely from ϕSaBov, mostly to recipient strains belonging to ST151. Phage DNA sequence analysis revealed that chromosomal DNA excision events from RF122 were highly specific to MGEs, suggesting sequence-specific DNA excision and packaging events rather than generalized transduction by a temperate phage. Disruption of the int gene in ϕSaBov did not affect phage DNA excision, packaging, and integration events. However, disruption of the terL gene completely abolished phage DNA packing events, suggesting that the primary function of temperate phage in the transfer of genomic islands is to allow for phage DNA packaging by TerL and that transducing phage particles are the actual vehicle for transfer. These results extend our understanding of the important role of bacteriophage in the horizontal transfer and evolution of genomic islands in S. aureus.     

Prevention of Bacteriophage Adsorption to Staphylococcus aureus by Immunoglobulin G

Normal human and rabbit sera when incubated with Staphylococcus aureus inhibit the adsorption of bacteriophages. The bacteriophage adsorption was also inhibited by separated normal immunoglobulin M (IgM), F(ab')(2), and Fab-fragments of IgG. No inhibition was obtained with myeloma IgG or Fc-fragments of normal human and rabbit IgG. The results indicate that the serum inhibition of bacteriophage adsorption to S. aureus is not due to a binding of IgG to protein A on the surface of S. aureus.     

Morphology and Physical Properties of Staphylococcus Bacteriophage P11-M15

The Group B Staphylococcus phage P11-M15 is shown to be 51% protein and 49% deoxyribonucleic acid (DNA). The intact virion has a molecular weight of 66.7 x 10(6) daltons. The purified viral DNA has a molecular weight of 32.7 x 10(6) daltons. The intact virion is shown to be composed of a polyhedral head which is attached at one of its vertices to a flexible tail having helical symmetry. The tail structure is terminated by a complex baseplate which has sixfold symmetry. The virion contains a single molecule of double-stranded DNA which has no apparent single-strand nicks or single-stranded terminal redundancies.     

Polyfunctional Penicillinase Plasmid in Staphylococcus epidermidis: Bacteriophage Restriction and Modification Mutants

Growth of multiply resistant Staphylococcus epidermidis BV strains at 45 C resulted in the independent elimination of tetracycline resistance, of kanamycin resistance coupled with oxacillin resistance, or of penicillinase activity. The pH optimum for the elimination of kanamycin and oxacillin resistance was 5.6, whereas that for elimination of penicillinase activity was 8.0. The genetic determinant for penicillinase activity was linked with the genetic determinants for the active uptake of mannitol and beta-glucosides, ribose fermentation, and phospho beta-glucosidase activity. The penicillinase linkage group also contained determinants for phage adsorption, restriction, and modification, and for growth factor requirements of still unknown nature. The same linkage group, which is apparently of extrachromosomal nature, was eliminated from several S. epidermidis BV strains. By selection for novobiocin resistance, deletion mutants affecting several loci of the penicillinase plasmid were isolated. The isolation of restriction-negative and modification-negative mutants which retained phage susceptibility allowed the investigation of restriction and modification phenomena. A preliminary deletion map of the polyfunctional penicillinase plasmid is proposed.     

Staphylococcus epidermidis BV: Antibiotic Resistance Patterns, Physiological Characteristics, and Bacteriophage Susceptibility

Staphylococcus epidermidis BV is a group of mannitol-fermenting coagulase-negative staphylococci characterized by multiple antibiotic resistance, very similar biochemical characteristics, and phage susceptibility. Clinical isolates belonging to this group are resistant to most antibiotics tested, including oxacillin, lincomycin, and novobiocin. The only antibiotic to which all tested strains are sensitive is vancomycin. Common biochemical traits of the tested S. epidermidis BV strains include fermentation of trehalose and ribose, phospho-β-glucosidase activity, growth on synthetic medium with amino acids as carbon source, and lack of deoxyribonuclease, phosphatase, lipase, and gelatinase activity. Some of these characteristics appear more frequently in mannitol-positive control strains than in mannitol-negative strains. S. epidermidis BV strains carry lysogenic phages with a host range restricted to this group. These phages allow the differentiation of individual strains.     

Microbiological Activities of Lysostaphin and Penicillins Against Bacteriophage 80/81 Strains of Staphylococcus aureus

Using 20 clinical isolates of S. aureus (all bacteriophage 80/81 type), we found that lysostaphin inhibits the growth of all cultures at concentrations significantly lower than those observed with any of eight penicillins, a penicillin-like compound (cephalothin), or fusidic acid (a steroid antibiotic). All test cultures were shown to be resistant to penicillin G, ampicillin, and propicillin. Of the remaining penicillins (all penicillinase-insensitive), oxacillin, nafcillin, cloxacillin, and cephalothin were approximately equal in antimicrobial activity. Ancillin was slightly less active, and methicillin was even lower in potency. Cultures varied more widely in susceptibility to fusidic acid. None of the clinical isolates tested was found to be resistant to lysostaphin.     

Bacteriophage conversion as a factor modifying the intensity of phagocytosis of Staphylococcus aureus by human leukocytes

Staphylococcus aureus NCTC 8325-4 and its eight variants lysogenized with phages responsible for the synthesis of staphylococcal staphylokinase were used for the study. Influence of phage conversion of S. aureus on its interaction with human leucocytes and influence of prophage on strain susceptibility to intracellular killing by human granulocytes without opsonins were evaluated. It was found that lysogenization of the strain with the bacteriophages decreased in each case reactivity of human leucocytes for staphylococcal strain what was expressed by lower bioluminescence values and by lower percentage of intracellular killing of bacterial cells carrying prophage.     

The Tape Measure Protein of the Staphylococcus aureus Bacteriophage vB_SauS-phiIPLA35 Has an Active Muramidase Domain

Tailed double-stranded DNA (dsDNA) bacteriophages frequently harbor structural proteins displaying peptidoglycan hydrolytic activities. The tape measure protein from Staphylococcus aureus bacteriophage vB_SauS-phiIPLA35 has a lysozyme-like and a peptidase_M23 domain. This report shows that the lysozyme-like domain (TG1) has muramidase activity and exhibits in vitro lytic activity against live S. aureus cells, an activity that could eventually find use in the treatment of infections.