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PubMed2005

Effects of growth in the presence of subinhibitory concentrations of dicloxacillin on Staphylococcus epidermidis and Staphylococcus haemolyticus biofilms.

Low concentrations of antibiotics can inhibit microbial adherence to medical device surfaces. However, little is known about the changes that occur in the physiology of bacteria within biofilms formed in the presence of subinhibitory (sub-MIC) concentrations of antibiotics. In this study, the densities and matrix compositions of biofilms formed by two coagulase-negative Staphylococcus species in the absence and in the presence of sub-MIC concentrations of dicloxacillin were evaluated. Biofilms formed in the presence of sub-MIC concentrations of dicloxacillin contained less biomass, and there were notable changes in the composition of the biofilm matrix. Changes in the spatial structure were also verified by confocal scanning laser microscopy, indicating that biofilms grown in the presence of sub-MIC concentrations of dicloxicilln had a lower cell density. Physiological alterations in the bacteria within biofilms grown in the presence of subinhibitory concentrations of the antibiotic were also evaluated. The results showed that there were differences in bacterial surface characteristics when cultures were grown in the presence of sub-MIC concentrations of dicloxacillin, including decreased hydrophobicity and decreased expression of the exopolysaccharide poly-N-acetylglucosamine. The elemental composition of the cell surface was also analyzed, and whereas in Staphylococcus epidermidis there were decreases in the oxygen and nitrogen contents, in Staphylococcus haemolyticus there were increases in these two parameters. Additionally, increases in resistance to several antibiotics were observed for the cells within biofilms formed in the presence of dicloxacillin.

Biofilms↗
PubMed1998

Receptor-mediated recognition and uptake of iron from human transferrin by Staphylococcus aureus and Staphylococcus epidermidis.

Staphylococcus aureus and Staphylococcus epidermidis both recognize and bind the human iron-transporting glycoprotein, transferrin, via a 42-kDa cell surface protein receptor. In an iron-deficient medium, staphylococcal growth can be promoted by the addition of human diferric transferrin but not human apotransferrin. To determine whether the staphylococcal transferrin receptor is involved in the removal of iron from transferrin, we employed 6 M urea-polyacrylamide gel electrophoresis, which separates human transferrin into four forms (diferric, monoferric N-lobe, and monoferric C-lobe transferrin and apotransferrin). S. aureus and S. epidermidis but not Staphylococcus saprophyticus (which lacks the transferrin receptor) converted diferric human transferrin into its apotransferrin form within 30 min. During conversion, iron was removed sequentially from the N lobe and then from the C lobe. Metabolic poisons such as sodium azide and nigericin inhibited the release of iron from human transferrin, indicating that it is an energy-requiring process. To demonstrate that this process is receptor rather than siderophore mediated, we incubated (i) washed staphylococcal cells and (ii) the staphylococcal siderophore, staphyloferrin A, with porcine transferrin, a transferrin species which does not bind to the staphylococcal receptor. While staphyloferrin A removed iron from both human and porcine transferrins, neither S. aureus nor S. epidermidis cells could promote the release of iron from porcine transferrin. In competition binding assays, both native and recombinant N-lobe fragments of human transferrin as well as a naturally occurring human transferrin variant with a mutation in the C-lobe blocked binding of 125I-labelled transferrin. Furthermore, the staphylococci removed iron efficiently from the iron-loaded N-lobe fragment of human transferrin. These data demonstrate that the staphylococci efficiently remove iron from transferrin via a receptor-mediated process and provide evidence to suggest that there is a primary receptor recognition site on the N-lobe of human transferrin.

Animals↗
PubMed1963

ABSCESS-FORMING FACTOR(S) PRODUCED BY STAPHYLOCOCCUS AUREUS. II. ABSCESS FORMATION AND IMMUNITY BY A STAPHYLOCOCCUS AND ITS MUTANTS.

Lam, Gow T. (Jefferson Medical College, Philadelphia, Pa.), Francis J. Sweeney, Jr., Charlotte M. Witmer, and Robert I. Wise. Abscess-forming factor(s) produced by Staphylococcus aureus. II. Abscess formation and immunity by a Staphylococcus and its mutants. J. Bacteriol. 86:87-91. 1963.-Three mutants were derived from a virulent parent strain of Staphylococcus aureus by ultraviolet irradiation. One mutant retained coagulase but lost its hemolytic activity; a second had no coagulase but retained its hemolysin; and a third contained hemolysin and bound coagulase but no free coagulase. The parent strain was coagulase-positive, hemolysin-positive, and possessed all the known extracellular products. All four strains were compared by bacteriophage typing, mannitol utilization, and antibiotic sensitivity tests. The four isolates were studied for their pathogenicity in Swiss albino mice and four strains of inbred mice. Their immunological characteristics as studied by repeated subcutaneous injections are reported. The importance of hemolysin and the coagulase in abscess formation is discussed. Local immunity was produced only by the parent strain, but abscesses were produced by all the strains containing coagulase.

Abscess↗
PubMed1990

Protective effect of Staphylococcus chromogenes infection against Staphylococcus aureus infection in the lactating bovine mammary gland.

The susceptibility of uninfected or Staphylococcus chromogenes-infected quarters to challenge with Staphylococcus aureus was measured. Seventeen S. chromogenes-infected quarters were challenged by infusion of S. aureus into the teat sinus; 47% (8 of 17) became infected and all 18 uninfected quarters challenged similarly with S. aureus became infected. No differences in daily milk yield were seen between uninfected quarters and S. chromogenes-infected quarters prior to S. aureus infusion. Postinfusion, milk yield for S. aureus-infected, S. chromogenes-infected, and S. chromogenes- and S. aureus-infected quarters differed. Somatic cell counts were elevated in S. chromogenes-infected quarters compared with uninfected quarters prior to S. aureus infusion. Somatic cell counts were not different between S. aureus- and S. chromogenes- and S. aureus-infected quarters postinfusion, but were different for S. chromogenes-infected quarters. Chloride concentrations in S. chromogenes- and S. aureus-infected quarters were different from either S. aureus-infected or S. chromogenes-infected quarters. Staphylococcus aureus colony forming units in quarters with preexisting S. chromogenes infections were lower than S. aureus colony-forming units in previously uninfected quarters. Possible protective mechanisms induced by S. chromogenes against superinfection by S. aureus are discussed.

Animals↗
PubMed2004

Development of a PCR test to differentiate between Staphylococcus aureus and Staphylococcus intermedius.

The presence of Staphylococcus intermedius in food remains unclear because routine laboratory analysis does not discriminate between S. intermedius and Staphylococcus aureus, a major cause of food poisoning. Both species share many phenotypic characteristics, including coagulase and thermonuclease production. In both species, some strains can produce enterotoxin and therefore can be the cause of food poisoning outbreaks. Although the ID32 Staph System (bioMérieux, SA, Marcy l'Etoile, France), based on a miniaturized phenotypic characterization, gives satisfactory results for discriminating between these two species, some rapid molecular PCR-based methods have been developed to identify S. aureus specifically, but they do not identify S. intermedius. Here, we developed a rapid, accurate, and discriminative multiplex PCR method that targets species-specific sequences in the nuc gene, which encodes thermonuclease in the two species. The test includes an internal positive control that targets a highly conserved region of 16S ribosomal RNA gene (rDNA). A total of 116 strains were used to validate our test. The test gave no signal on the following Staphylococcus species: S. epidermidis, S. chromogenes, S. hyicus, S. warneri, S. xylosus, S. lentus, and S. sciuri. It allowed a 100% successful discrimination between S. aureus (44 strains tested) and S. intermedius (57 strains) isolated from different origins.

Animals↗
PubMed2005

[In vitro activity of linezolid, moxifloxacin, levofloxacin, clindamycin and rifampin, alone and in combination, against Staphylococcus aureus and Staphylococcus epidermidis].

Information about the in vitro effect of combinations of anti-staphylococcal agents on staphylococci is scarce. The aim of the study was to evaluate the in vitro activity of linezolid, moxifloxacin, levofloxacin, clindamycin and rifampin, alone or in combination, against Staphylococcus spp. Two Staphylococcus aureus and two Staphylococcus epidermidis strains isolated from blood cultures were studied using the killing curve method. The combinations analyzed were linezolid+moxifloxacin, linezolid+levofloxacin, linezolid+clindamycin, linezolid+rifampin, moxifloxacin+rifampin, moxifloxacin+clindamycin, levofloxacin+rifampin and levofloxacin+clindamycin. The following concentrations (mg/l) were used: 8 and 16 for linezolid, 2 for moxifloxacin, 3 for levofloxacin, 2 for clindamycin and 2 and 5 for rifampin. The activity was considered synergistic when a reduction in growth of at least 2 log(10) was produced with the combination in comparison to the most active antibiotic alone; antagonistic when a growth of at least 2 log(10) was produced with the combination in comparison to the most active antibiotic alone; and indifferent if the variation was less than 1 log(10). Linezolid and clindamycin were bacteriostatic, while moxifloxacin and levofloxacin were bactericidal. Rifampin was bacteriostatic against S. aureus and bactericidal against S. epidermidis. Linezolid and clindamycin reduced the bactericidal activity of levofloxacin and moxifloxacin, however an antagonistic effect was only observed against S. aureus. Other combinations of linezolid, rifampin, clindamycin, levofloxacin or moxifloxacin were indifferent. Linezolid and clindamycin antagonize the bactericidal activity of fluorquinolones against staphylococci. There was no difference between any other combinations against either S. aureus or S. epidermidis.

Acetamides↗
PubMed1985

Resistance plasmids for inducible macrolide-lincosamide resistance in Staphylococcus simulans and Staphylococcus epidermidis.

Localization and genetic nature of inducible macrolide resistance determinants in some coagulase negative staphylococci (CNS) were studied and compared with those in Staphylococcus aureus. An 1.7-megadalton R-plasmid, pEI 1107, mediating inducible resistance to macrolides and lincosamides was present in part of Staphylococcus simulans and Staphylococcus epidermidis strains isolated in the Central Hospital for Infectious Diseases. Two other plasmids were harboured by S. simulans LK 6108 strain. One of these plasmids, pEI 6108 (molecular mass 5.2 Md) was encoded for inducible macrolide-lincosamide resistance, and the second one, pE 6108 (molecular mass 4.9 Md) for constitutive marcolide resistance. The similarity in size and phenotype of small plasmids in CNS and S. aureus suggest a common origin of these resistance determinants.

DNA, Bacterial↗
PubMed1995

The effect of ethanol ingestion on killing of Streptococcus pneumoniae, Staphylococcus aureus and Staphylococcus epidermidis by rat neutrophils.

The precise effects of chronic ethanol ingestion on the role of neutrophil function in pneumococcal pneumonia have not been fully delineated. In this study, the bactericidal capacity of polymorphonuclear leucocytes (PMNL) from rats pair-fed an ethanol-containing liquid diet or a liquid control diet was compared both in vitro and in vivo. The PMNL were allowed to phagocytose several bacterial species in vitro, and intracellular killing after 1h was determined by plate counts. There was no significant difference in killing of Streptococcus pneumoniae types 6B or 37, Staphylococcus aureus or Staphylococcus epidermidis by PMNL from ethanol-fed and pair-fed rats (E-PMNL and P-PMNL, respectively). However, E-PMNL killed significantly less of Streptococcus pneumoniae types 10A, 14 and 19F. To corroborate these results in vivo, rats were infected transtracheally, and quantitative lung counts were performed 1 week post infection. Streptococcus pneumoniae types 6B and 37, as well as Staphylococcus aureus, were effectively cleared from the lungs of both groups of rats. Streptococcus pneumoniae types 10A, 14 and 19F, however, were cleared well from the lungs of pair-fed but not ethanol-fed animals. These data suggest that chronic ethanol ingestion induces a strain-specific deficit in neutrophil bactericidal activity against certain S. pneumoniae which does not extend to commonly encountered staphylococci.

Alcoholism↗
PubMed1995

Comparative biochemical and molecular analysis of the Staphylococcus hyicus, Staphylococcus aureus and a hybrid lipase. Indication for a C-terminal phospholipase domain.

The lipase gene, geh, from Staphylococcus aureus NCTC8530 was cloned in Staphylococcus carnosus. DNA sequencing revealed an open reading frame (ORF) of 2046 nucleotides encoding a 682-amino-acid protein with a molecular mass of 76900 Da. Determination of the transcriptional start site revealed a 203-nucleotide mRNA leader. Expression of geh in the protease-negative S. carnosus (pT181copSA22) resulted in overexpression of a 83-kDa lipase found in the culture supernatant. N-terminal protein sequencing and sequence comparison with three other staphylococcal lipases suggest that this lipase is organised as a pre-pro-enzyme. The substrate specificity of this lipase is different from the Staphylococcus hyicus lipase. The S. hyicus lipase expressed both a high Ca(2+)-dependent phospholipase and lipase activity while the S. aureus lipase lacked this phospholipase activity and its activity with tributyrylglycerol or p-nitrophenyl octanoate is hardly stimulated by Ca2+ ions. A hybrid protein was constructed in which the C-terminal 146 residues of the S. hyicus lipase were substituted by 145 residues of the C-terminal of the S. aureus lipase, which contains the proposed active-site amino acids Asp602 and His641. The hybrid enzyme was still active and revealed an intermediary enzymic activity. The most striking effect was that it had lost the S. hyicus-specific phospholipase activity and that, in contrast to the two parental enzymes, its activity with p-nitrophenyl octanoate became highly sensitive to the presence of Ca2+. These observations suggest that the C-terminal domain of the S. hyicus lipase strongly contributes to the binding pocket of the polar headgroup of phospholipids. The Ca(2+)-binding site seems to be located in the N-terminal fragment of the S. hyicus lipase. The fact that two closely related enzymes differ in the need for Ca2+ underscores the notion that it plays a structural rather than a catalytic role.

Amino Acid Sequence↗
PubMed2003

Staphylococcus lugdunensis endocarditis--the hidden peril of coagulase-negative staphylococcus in blood cultures.

Reported here is a successfully treated case of native mitral valve endocarditis caused by Staphylococcus lugdunensis and a review of 47 similar cases reported in the English literature. In the literature review, perineal skin flora appeared to be the source of the organism in patients with endocarditis. Staphylococcus lugdunensis is generally susceptible in vitro to beta-lactam agents. If speciation is not performed, these bacteria might be mistaken for Staphylococcus epidermidis, a relatively avirulent bacterium that is a common contaminant of cultures. Prompt speciation can lead to earlier recognition of endocarditis and possibly enable earlier surgical intervention with improved outcome for this high-mortality infection. Multiple positive blood cultures yielding coagulase-negative staphylococci should be identified to the species level; endocarditis or another intravascular source of infection should be sought.

Adult↗
PubMed2005

Successful oral pristinamycin therapy for osteoarticular infections due to methicillin-resistant Staphylococcus aureus (MRSA) and other Staphylococcus spp.

OBJECTIVES: Oral treatment regimens for multiresistant methicillin-resistant Staphylococcus aureus (MRSA) infections are limited. In Australia, rifampicin plus fusidic acid is the usual treatment regimen following glycopeptide therapy but many patients are intolerant of this; some isolates are resistant; new oxazolidinones are expensive for routine use. Pristinamycin is a possible alternative and we report our experience with this agent. METHODS: The Department of Microbiology and Infectious Diseases, South Western Area Pathology Service treats patients drawn from the South Western Sydney Area Health Service that houses approximately 800,000 people and contains approximately 2000 acute care public hospital beds. Patients prescribed pristinamycin between 1 September 2000 and 31 January 2000 were identified from hospital pharmacy records. A retrospective chart review was performed. Accepted clinical definitions of osteomyelitis and septic arthritis were used. RESULTS: Twenty-seven patients were identified with osteoarticular infections. Twenty-four cases involved Staphylococcus aureus (multiresistant MRSA in 21 cases); three involved Staphylococcus epidermidis sensu stricto; four cases involved multiple organisms. Nineteen cases received pristinamycin monotherapy; the others received various combinations (fusidic acid with five; other antibiotics with three). Therapy was generally well tolerated; no haematological or biochemical toxicity was detected. Seven patients had minor gastrointestinal disturbance; and one developed rash. Four patients required dose reduction. Only four patients ceased pristinamycin due to intolerance. Treatment outcome was evaluated in 23 cases; cure was effected in 16 cases, five were successfully suppressed and two failed. There were no deaths. CONCLUSIONS: Oral pristinamycin is well tolerated and an important additional agent to treat osteoarticular infections with multiresistant MRSA and other staphylococci.

Administration, Oral↗
PubMed2002

Methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus ocular surface infection efficacy of chloramphenicol eye drops.

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MR-CNS) are two major multidrug-resistant pathogens. In this paper we report the prevalence of MRSA and MR-CNS in ocular surface infections. METHODS: We investigated the proportion of MRSA and MR-CNS in bacterial isolates from conjunctiva of elderly patients with and without bacterial conjunctivitis. The relationship between conjunctival MRSA carriers and general background conditions was studied. We evaluated the efficacy of chloramphenicol eye drops in the treatment of MRSA conjunctivitis. We also investigated the presence of MRSA and MR-CNS in lid skin and conjunctiva of patients with atopic dermatitis. RESULTS: In conjunctival bacterial flora of elderly patients the proportion of MRSA in S. aureus was 57%, and the proportion of MR-CNS in coagulase-negative Staphylococcus was 25%. Conjunctival MRSA carriers were more likely to have anemia, malignant tumor, liver dysfunction, and dementia, and to be postoperation and chronically bedridden. The efficacy rate of chloramphenicol eye drops in the treatment of MRSA conjunctivitis was 81%. In conjunctival sacs of patients with atopic dermatitis, S. aureus was the most frequent species (48%), and the proportion of MRSA was 18%. CONCLUSION: Methicillin-resistant S. aureus and MR-CNS are widespread in elderly hospitalized patients and in patients with atopic dermatitis. Chloramphenicol eye drops were useful for the treatment of MRSA ocular surface infections.

Aged↗
PubMed1997

Gene replacement in Staphylococcus carnosus and Staphylococcus xylosus.

A system for high-efficiency gene replacement in Staphylococcus carnosus and Staphylococcus xylosus has been developed, that is based on temperature-sensitive Escherichia coli-Staphylococcus shuttle vectors for fragment delivery and erythromycin resistance cassettes to facilitate selection of genomic copies of disrupted genes. The approach was tested by constructing a phosphotransferase-deficient mutant of S. carnosus and an S. xylosus mutant strain unable to utilize sucrose. Allelic replacements were observed at rather high frequencies, ranging from approximately 10% for the ptsI gene in S. carnosus up to 50% for the scrB gene in S. xylosus. These differences most likely reflect the length of homology rather than strain-specific variations in recombination efficiencies. Apart from the staphylococcal species tested in this study, the system appears to be applicable in other staphylococci.

Alleles↗
PubMed1980

[Staphylococcus aureus infection in chickens in industrialized poultry units. 3. Experimental infection of chickens and comparison of pathogenicity of Staphylococcus aureus of different origin].

Day-old chicks were subcutaneously infected with Staphylococcus aureus strains of site variety gallinae and crystalviolet Type A. The lysis patterns involved were with phages 84 as well as with phages 53, 77, and 84 of the international base scheme for human staphylococci. In fowl with synovitis and arthritis, osteomyelitis, dermatitis, and septicaemia, 52 of 57 tested strains (91.2 per cent) produced on the site of injection pathognomic oedematous-haemorrhagic and necrotising changes of the skin and hypodermis (haemorrhagic dermatitis) in a way which is characteristic also of natural diseases. However, no specific skin changes could be produced by subcutaneous infection of nine strains of site variety hominis or undefinable category with differentiated biochemical properties and lysis patterns. They had been isolated from cases of compound infection, salpingitis and wound infections as well as from one case of arthritis. Fifty-seven strains, obtained from mammals, were tested subcutaneously, on day-old chicks, among them 21 strains of site varieties of bovis, canis, ovis, and hominis. However, only four of those strains, isolated from miscarried pig foetuses and cattle with mastitis, caused, oedematisation and exudation (7.02 per cent), but no haemorrhagia and only minor lysis and necrosis of skin. The minimum dose required to induce haemolytic dermatitis was 11 x 10(3) pathogens, and the lowest lethal dose of six tested strains was between 11 x 10(5) and 26 x 10(7) pathogens. The lowest dose of mammalian strains with lethality to day-old chicks was [10 bis]10(4) times as high as the lowest dose of fowl strains. Subcutaneous infection of day-old chicks has worked well as a high-speed test by which to differentiate between fowl-pathogenic Staphylococcus aureus strains, on the one hand, and mammalian strains, on the other. The need for delimitation of such strains has been confirmed by the above experimental infections. Against the background of the above results, guidelines are proposed for the control of Staphylococcus aureus infection of fowl.

Animals↗
PubMed1995

Multiresistance in Staphylococcus spp. blood isolates in Finland with special reference to the distribution of the mecA gene among the Staphylococcus epidermidis isolates. The Finnish Study Group for Antimicrobial Resistance.

A total of 570 Staphylococcus spp. blood isolates collected in Finland in 1991 were tested for susceptiblity to oxacillin and 19 additional antimicrobial agents. The Staphylococcus epidermidis isolates were also analyzed for the presence of the mecA gene by the polymerase chain reaction (PCR). Of the 238 S. epidermidis, 137 (58%) were in vitro identified as methicillin-resistant and 5 (2%) exhibited oxacillin MICs between 1 and 3 micrograms/ml. All these isolates were positive for the mecA gene in PCR as an indication of genetic resistance to methicillin, while none of the remaining 96 S. epidermidis isolates (oxacillin MICs < or = 0.25 microgram/ml) was positive. Multiresistance was observed in 123 (87%) of the 142 mecA-positive S. epidermidis. Of the 332 Staphylococcus aureus isolates, only one (0.3%) was phenotypically resistant to methicillin; the strain was also resistant to three other unrelated classes of antimicrobials. True methicillin resistance of this strain was manifested by the presence of the mecA gene in PCR. Based on these results, multiresistance was still extremely rate among the S. aureus in our country, whereas among the S. epidermidis as many as half of the blood isolates in central hospitals were multiresistant.

Bacterial Proteins↗
PubMed1963

The vivo interaction between staphylococcus bacteriophage and Staphylococcus aureus.

Staphylococcus bacteriophage 81 is capable of in vivo interaction with Staphylococcus aureus, Type 80/81. This is immediately made evident by increased levels of bacteriophage and concomitant survival of 81 per cent infected mice. The reaction is dependent upon the use of active, type-specific bacteriophage. The maximal protective effect is observed at a bacteriophage to bacteria ratio of 1:2 and decreased quantities of bacteriophage result in decreased protection. Time and sequence of administration are also determining factors. It is evident that bacteriophage administered intravenously is capable of interaction with the infecting bacterial cell at the site of infection. In vivo produced bacteriophage is apparently eliminated or otherwise rendered nondetectable fairly rapidly, occurring within a period of 5 to 10 days. However, it appears that host defense mechanisms are stimulated in the process and actively play a protective role against subsequent challenge inocula administered up to 3 weeks later.

Animals↗
PubMed2006

Applications of LightCycler Staphylococcus M-GRADE assay to detect Staphylococcus aureus and coagulase-negative staphylococci in clinical blood samples and in blood culture bottles.

We evaluated the applicability of the LightCycler Staphylococcus M(GRADE0 assay on artificially infected blood samples from healthy donors and on clinical specimens of 31 hospitalized patients. The sensitivity and specificity of the assay for detecting Staphylococcus aureus was 100% in blood samples, and 100% in blood culture bottles, when data from the BACTEC 9120 blood culture system were taken as gold standard. The same specificity and sensitivity was found during the search for CoNS (Coagulase Negative Staphylococci) in blood culture bottles, whereas a 93.33% sensitivity and 100% specificity was observed for detecting CoNS directly in blood clinical specimens.

Bacteremia↗