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PubMed1980

Rarity of gene transfer between animal and human isolates of Staphylococcus aureus in vitro.

Antibiotic-resistant Staphylococcus aureus strains of animal origin were studied for transfer of resistance to human strains in vitro, with special reference to tylosin, an antibiotic which is used only in animals. Resistance to tylosin in animal and human strains was part of a constitutive resistance to all macrolide antibiotics. Resistance to tylosin could not be transferred from animal to human strains in vitro. Transfer of other resistances occurred between few strains and at low frequency. Resistance determinants from only seven animal cultures (out of 196 tested) could donate resistance to human strains in mixed cultures. The pattern of metal ion resistance was markedly different in animal and human strains: this supports the conclusion that spontaneous transfer between them is rare in nature.

Animals↗
PubMed1986

The mitogenic properties of lipoteichoic acid from Staphylococcus aureus.

Lipoteichoic acid (LTA) isolated from Staphylococcus aureus Cowan I induced an in vitro blastogenic response in isolated mononuclear cells (MNC). Seventeen of 20 normal donors responded strongly, with peak response after 3-5 days of incubation. Significant stimulation was also obtained with human cord blood MNC from 3 donors, further indicating that the stimulation was due to a general mitogenic effect. The mitogenicity of deacylated LTA (dLTA) was similar to that of LTA. Binding of LTA to isolated MNC was demonstrated by an indirect immunofluorescent technique staining with specific rabbit anti-LTA antibodies and by rosette inhibition experiments. Results obtained in cell fraction experiments indicated that LTA had a monocyte dependent mitogenic effect on T lymphocytes.

Antilymphocyte Serum↗
PubMed1997

Gene of LukF-PV-like component of Panton-Valentine leukocidin in Staphylococcus aureus P83 is linked with lukM.

Staphylococcus aureus P83 (ATCC 31890) produces five components, I to V for synergistic toxins, leukocidin and gamma-hemolysin [Sudo et al., Biosci. Biotech. Biochem., 56, 1786-1789 (1995)]. We report here the identification of component II, which is designated LukF-PV(P83) and its gene (lukF-PV(P83)). The lukF-PV(P83) gene was found to be one base downstream of the stop codon of the lukM gene. The deduced amino acid sequence of LukF-PV(P83) showed 78.4% identity with that of LukF-PV. The lukM and lukF-PV(P83) genes were encoded as one operon like that of Panton-Valentine leukocidin.

Amino Acid Sequence↗
PubMed1986

[Nucleotide sequence and physical map of kanamycin-resistant plasmid pUB110 from Staphylococcus aureus].

The complete nucleotide sequence of Staphylococcus aureus plasmid pUB10 was determined. The sequence consists of 4545 b.p. and contains 64% A-T and 36% G-C pairs. pUB110 was found to contain four open reading frames, capable of coding for polypeptides having more than 80 amino acids. All the putative polypeptides are coded for by one DNA strand. The molecular weights of four putative polypeptides are (in kilodaltons): A-49.5; B-38.8; C-28.8 and D-9.5. Polypeptide C is involved in kanamycin resistance. Polypeptide B is, possibly, involved in pUB110 replication. No role has yet been established for polypeptides A and D, since deletions in their coding sequences have no detectable effect on any properties of pUB110 plasmid.

Base Sequence↗
PubMed1982

Bacteriophage-mediated acquisition of antibiotic resistance by Staphylococcus aureus type 88.

Antibiotic-resistant Staphylococcus aureus strains of phage type 88, lysogenic for phage 188, when grown in mixed culture with a nonlysogenic novobiocin-resistant strain, acquired novobiocin resistance at a high rate from the nonlysogenic strain. With most strains of phage type 88, there was no detectable transfer of resistance from lysogenic to nonlysogenic cells. Lysogenization with phage 188 of phage-sensitive strains conferred on the lysogenized cells the ability to acquire chromosome and plasmid resistance markers. The acquisition of novobiocin resistance in liquid cultures depended on the aeration of the culture, cell density, and the presence of Ca2+. Pronase, and to a lesser degree other proteinases, increased the rate of acquisition of chromosome- and plasmid-determined resistance markers by cells lysogenic for phage 188.

Anti-Bacterial Agents↗
PubMed1983

Bacteria-immune system interactions. IX. Modulation of human and murine cytotoxic reactions by crude lipoteichoic acid extracted from Staphylococcus aureus.

Crude lipoteichoic acid extracts of Staphylococcus aureus (SA-LTA) or Bacillus glogigii (Bg-LTA) inhibited cytotoxic reactions when added at day 0 to human or murine mixed lymphocyte reactions (MLR). The inhibition was dose dependent, and at low Sa-LTA concentrations it did not require reduction of thymidine incorporation into effector lymphocytes. In the murine system, Sa-LTA was a much more potent inhibitor than Bg-LTA. LTAs of both origin also could inhibit cytotoxic reactions when bound to stimulator cells. However, the LTA derivatized stimulator cells were much more inhibitory in the human than in the murine MLR. The inhibition of human cytotoxic reaction by Sa-LTA derivatized stimulator was not associated with a significant reduction of thymidine incorporation in effector cells.

Animals↗
PubMed1999

Ciprofloxacin resistanceamong community-derived methicillin-resistant Staphylococcus aureus (MRSA) strains.

Methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as a nosocomial pathogen in Europe and North America for almost 3 decades. More recently it has emerged as a problem in long-term care facilities. However, It has been less frequently considered a pathogen in community-acquired infections, where it is most often seen in intravenous drug users. Consequently there has been very few studies, particularly in Bangladesh, documenting incidence of ciprofloxacin-resistance among MRSA in community patients. We tested clinical isolates from outdoor patients for ciprofloxacin resistance among MRSA strains, using in vitro susceptibility tests by standard disk diffusion technique. Results show significantly high incidence of ciprofloxacin resistance among MRSA isolates in these patients.

Anti-Infective Agents↗
PubMed1983

Evolution of antibiotic resistance genes: the DNA sequence of a kanamycin resistance gene from Staphylococcus aureus.

The kanamycin resistance gene from Staphylococcus aureus has been sequenced and its structure compared with similar genes isolated from Streptomyces fradiae and from two transposons, Tn5 and Tn903, originally isolated from Klebsiella pneumoniae and Salmonella typhimurium, respectively. The genes are all homologous but, since their common ancestor, have undergone extensive divergence, with more than 43% divergence between the closest pair. The phylogeny of the genes cannot be made congruent to the phylogeny of the taxa from which they were isolated without requiring rather improbable differences in rates. One is therefore led to conclude that there have been multiple occurrences of gene transfer between these species. Thus, although they are homologous, they are neither orthologous nor paralogous. It is suggested that homologous genes of this type be called xenologous.

Amino Acid Sequence↗
PubMed1990

Characterization of gentamicin-resistant respiratory-deficient (res-) variant strains of Staphylococcus aureus.

Exposure of sensitive cells of Staphylococcus aureus to concentrations of gentamicin higher than the minimal inhibitory concentration, results in the recovery of low level resistant strains with a greatly altered phenotype (variants). Because the phenotypic alteration in these strains is so great the expected diagnostic characterization of these variants as S. aureus is obscured. Starting with a genetically-marked parent strain, a comprehensive cytological, physiological, morphological, genetic and biochemical analysis of the variants isolated from it was carried out. The genetic lineage of the variants to the parent was also established by DNA/DNA hybridization. Variants result from mutations in the hemin biosynthesis locus, the effect of which is to disrupt the synthesis of components of the electron transport system, lipid synthesis and selected nucleotide synthesis. Thus the strains are defective in aerobic and anaerobic respiration, (res-), in active transport of aminoglycosides (which confers low level resistance), export of characteristic exo-enzymes, and in cell wall composition and structure.

Bacteriophages↗
PubMed2005

Community-associated methicillin-resistant Staphylococcus aureus: a review.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common bacterial pathogen responsible for a variety of infections in both children and adults. Treatment of infections caused by this organism is problematic due to its resistance to many drugs. Recent reports of community-associated MRSA (CA-MRSA) infections in patients with no known risk factors have serious public health implications. Therapeutic options for these infections are untested; therefore, the potential exists for high morbidity and mortality. Recently, clinical definitions have been established, and new molecular approaches have allowed investigators to distinguish CA-MRSA more easily from traditional nosocomial-derived MRSA strains. Identifying potential risk factors for CA-MRSA acquisition and fully characterizing the epidemiologic, clinical, and molecular properties of these strains are necessary to provide effective therapeutic guidelines.

Anti-Bacterial Agents↗
PubMed1998

Identification of a gene essential for O-acetylation of the Staphylococcus aureus type 5 capsular polysaccharide.

The Staphylococcus aureus serotype 5 capsular polysaccharide (CP5) has a trisaccharide repeating unit of (-->4)-3-O-Ac-beta-D-ManNAcAp-(1-->4)-alpha-L-FucNAcp-(1-->3 )-beta-D-FucNAcp-(1-->). Tn918 mutagenesis of strain Reynolds yielded a mutant that produced wild-type levels of O-deacetylated CP5. The site and orientation of the single transposon insertion in mutant JL232 were determined by analysis of Southern blots and amplification of DNA flanking the transposon. DNA sequencing revealed that Tn918 was inserted within an open reading frame of 627 bp. The predicted amino acid sequence encodes a protein of approximately 26 kDa with homology to members of the NodL-LacA-CysE family of bacterial acetyltransferases. Southern blot analysis showed that genes similar to cap5H were present only in strains of S. aureus belonging to capsular serotypes 2, 4 and 5. In an in vitro assay, the parental strain was more resistant to opsonophagocytic killing than the mutant strain. In a mouse model of staphylococcal infection, the parental strain was able to seed the bloodstream from the peritoneal cavity and colonize the kidneys more efficiently than the O-deacetylated mutant. When cap5H was provided to the mutant in trans, it fully restored CP5 O-acetylation. The virulence of the complemented mutant strain closely approximated that of the parental strain.

Abscess↗
PubMed2004

Identification and biological evaluation of grapefruit oil components as potential novel efflux pump modulators in methicillin-resistant Staphylococcus aureus bacterial strains.

Methicillin-resistant Staphylococcus aureus (MRSA) and MSSA strains were treated with: (a) grapefruit oil (GFO) components, isolated by chromatography and characterised by NMR and mass spectroscopy; (b) antimicrobial agents, or (c) a combination of both to evaluate (MIC determination) intrinsic antibacterial activity and to determine whether GFO components could modulate bacterial sensitivity to the anti-bacterial agents. Preliminary data suggested that the grapefruit component 4-[[(E)-5-(3,3-dimethyl-2-oxiranyl)-3-methyl-2-pentenyl]oxy]-7H-furo[3,2-g]chromen-7-one (2) enhances the susceptibility of test MRSA strains to agents, e.g., ethidium bromide and norfloxacin, to which these micro-organisms are normally resistant.

Anti-Bacterial Agents↗
PubMed2001

Crystallization and preliminary X-ray diffraction studies of glycerol 3-phosphate cytidylyltransferase from Staphylococcus aureus.

Glycerol 3-phosphate cytidylyltransferase from Staphylococcus aureus (TarD(Sa)) has been expressed in Escherichia coli, purified to homogeneity and crystallized. The strategy used for determining crystallization conditions employed hanging-drop sparse-matrix screens and required a combination of three different optimization approaches. Specifically, the presence or absence of cofactors needed to be surveyed, the effects of small-molecule additives required exploration and the rate of vapour-diffusion had to be varied in order to obtain crystals of TarD(Sa) suitable for diffraction studies. Crystals thus obtained belong to the space group P3(1)21, with unit-cell parameters a = b = 92.2, c = 156.1 A, and contain four TarD(Sa) molecules per asymmetric unit. The resolution limit observed for these crystals using synchrotron radiation is 3.0 A.

Cloning, Molecular↗
PubMed1993

The use of monoclonal antibodies for studying the biological properties of Staphylococcus aureus endo-beta-N-acetylglucosaminidase.

Staphylococcus aureus endo-beta-N-acetylglucosaminidase (SaG) has been suggested to function as a virulence determinant which interferes with the host cellular immune response. To further characterize the biological properties of SaG, monoclonal antibodies (mAbs) were raised against purified SaG. Four IgG1 subclass mAbs were obtained, none of which reacted with the reduced, sodium dodecyl sulphate pretreated or boiled enzyme. The ability of the mAbs to react with the enzymes present in supernatants obtained from 197 S. aureus strains indicated that they recognized epitopes which are highly conserved; bacteriolytic enzymes produced by staphylococci other than S. aureus did not show any cross-reactivity. After pretreatment of SaG with mAbs (mAb-SaG molar ratios varying from 1 to 20), it was shown that all selected mAbs caused, at a mAb:SaG molar ratio of 10, a 90% inhibition of SaG bacteriolytic activity and a statistically significant reduction of its ability to interfere with phagocytosis by human polymorphonuclear leukocytes. All selected mAbs reacted with several commercially available exo-beta-N-acetylglucosaminidases; mAb C1/10-11 also reacted with chicken and turkey egg muramidases and, at a mAb:SaG molar ratio of 10, inhibited their bacteriolytic activity by 97%. This suggests that one or more epitopes present in the above exo-glucosaminidases and muramidases share some degree of homology with others present in SaG.

Acetylglucosaminidase↗
PubMed1997

Variation in the agr-dependent expression of alpha-toxin and protein A among clinical isolates of Staphylococcus aureus from patients with septicaemia.

In Staphylococcus aureus synthesis of many virulence factors is regulated by the agr locus. The regulatory molecule RNAIII, induced by agr, activates transcription of the alpha-toxin gene, hla, while it acts as a repressor of the protein A gene, spa. Forty clinical strains of S. aureus from human blood cultures were analysed for alpha-toxin and protein A production. An inverse correlation between alpha-toxin and protein A production was found in most strains. The levels of alpha-toxin and protein A production varied significantly among strains, which indicates various levels of the regulator, RNAIII. This was confirmed by selecting strains producing different amounts of alpha-toxin, showing that the variations in toxin production are due to the variations of RNAIII transcript. However, in one of the selected strains which produced high levels of alpha-toxin, OR153, although RNAIII is also strongly expressed, the specific hla mRNA was unexpectedly low. One partial explanation for the high alpha-toxin production by this clinical isolate might be its lack of extracellular proteases.

Bacteremia↗
PubMed1994

In vitro development and stability of tolerance to cloxacillin and vancomycin in Staphylococcus aureus.

The stability of tolerance of Staphylococcus aureus during subculturing at 37 degrees C and development of this property after repeated exposure to cloxacillin or vancomycin were investigated in vitro. Four of five tolerant strains lost this property during repeated subculturing at 37 degrees C for 50 days. Conversely, tolerance emerged in two of four nontolerant strains after repeated cycles of exposure to 25 micrograms of cloxacillin/ml or 10 micrograms of vancomycin/ml alternating with growth in antibiotic-free medium. Previous in vivo exposure to cloxacillin did not enhance the development of tolerance in vitro. MICs of both cloxacillin and vancomycin did not change significantly during this procedure. Whether the conversion of nontolerant strains to the tolerant state can also occur during antibiotic exposure in treatment of patients remains to be determined.

Cloxacillin↗
PubMed1995

Labile antibiotic resistance in Staphylococcus aureus.

Twenty-two isolates of Staphylococcus aureus, recovered from patients over a period of about one year, exhibited low level resistance to mupirocin, developed a salmon pink colour on culture and 21 had the same phage-type. However the plasmid profiles and associated antibiotic resistances differed. Digestion of cellular DNA with SmaI showed that two isolates from a single patient had a markedly different pattern to the remainder, and that six others differed by one band, though these formed groups of one and five isolates. This episode apparently represents a small outbreak of colonization or infection, which would have been missed but for the unusual pigmentation of the isolates recovered, and illustrates the difficulties of relying on a single typing system.

Anti-Bacterial Agents↗
PubMed2001

Mupirocin resistance among Malaysian isolates of methicillin-resistant Staphylococcus aureus.

Four hundred methicillin-resistant Staphylococcus aureus strains (MRSA) from different geographical areas in Malaysia were tested for mupirocin susceptibility using minimum inhibitory concentration (MIC) determination. The majority of these strains (98.75%) were susceptible to mupirocin with MICs of < or = 4 mg/l. Fifty-percent of these strains had MICs of 0.125 mg/l or less while 90% of the strains had MICs of 1 mg/l or less. Mupirocin resistance was detected in five strains (1.25%) and one of these (0.25%) had an MIC of 64 mg/l and the other four strains (1%), high-level resistance with MICs > 512 mg/l. Even though the rate of mupirocin resistance in MRSA is still low in Malaysia, its presence calls for a strict policy on mupirocin usage in Malaysian hospitals.

Anti-Bacterial Agents↗