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PubMed1998

Molecular cloning and DNA sequencing of the Staphylococcus aureus UDP-N-acetylmuramyl tripeptide synthetase (murE) gene, essential for the optimal expression of methicillin resistance.

The Tn551 insertion in mutant RUSA235 of a highly methicillin resistant Staphylococcus aureus strain results in drastic reduction in the level of methicillin resistance and abnormalities, both in the composition of the peptidoglycan and of the cell wall precursor pool. Cloning and sequencing of the inactivated gene indicates that it is the murE gene of Staphylococcus aureus.

Amino Acid Sequence↗

PubMed2005

Genetic analysis of mec A homologues in Staphylococcus sciuri strains derived from mastitis in dairy cattle.

Methicillin-resistant Staphylococcus aureus (MRSA) is defined by the presence of the mec A gene, which is considered to have been transferred horizontally from unknown bacterial species to S. aureus. As a candidate of evolutionary precursor of the mec A, the mec A-like gene (mec A homologue), which is ubiquitously present in Staphylococcus sciuri has been proposed. In this study, sequences of the mec A homologue in four S. sciuri strains (SCBM 1-SCBM 4) derived from dairy cows were determined to analyze their genetic characteristics and relatedness to mec A and the mec A homologue reported so far. The mec A-like gene sequences of the four S. sciuri strains were identical with each other and were considered to encode a product comprising 665 amino acids that is one amino acid smaller in size than products of mec A-like gene reported previously for S. sciuri strains K1, K1 1, and K3 (mec A1). The mec A homologue of a representative strain SCBM 1 showed 79.3--79.8% sequence identity to MRSA mec A and 93.4--94.4% identity to mec A homologues reported for the three S. sciuri strains. Between S. sciuri strain SCBM 1 and strains K1, K1 1, or K3, amino acid sequence identities in transpeptidase domain of the mec A-like gene product (98.2--98.5%) were higher than those in the transglycosylase domain (92.1--94.3%). In addition, SCBM 1 showed extremely high sequence identities of hsp 60, sodA, and rpoB genes (more than 98.7%) to S. sciuri strains, while showing 70.3--94.2% identity of these genes to other staphylococcal species. These findings indicated that mec A homologues in S. sciuri may be genetically more divergent than mec A in MRSA and methicillin-resistant coagulase-negative staphylococci.

Amino Acid Sequence↗

PubMed2004

Experimental efficacy study of coated VICRYL plus antibacterial suture in guinea pigs challenged with Staphylococcus aureus.

BACKGROUND: This study evaluated the ability of coated polyglactin 910 suture with triclosan (Coated VICRYL Plus Antibacterial) suture to inhibit the colonization of bacteria on the suture after direct in vivo inoculation challenge with Staphylococcus aureus utilizing a guinea pig model. METHODS: One control suture (4-5 cm) and one test suture (4-5 cm) were implanted subcutaneously in the dorsal-lateral regions (control on the left side, test on the right side, approximately 5 cm apart) in 16 female Hartley guinea pigs (300-400 g) via a 20-gauge catheter. Each implantation site was challenged directly with 2.1 x 10(4) colony forming units (cfu) of Staphylococcus aureus through the indwelling catheter. The test material was coated polyglactin 910 suture with triclosan (2-0, dyed), and the control material was coated polyglactin 910 suture (2-0, undyed). At 48 h, suture articles were explanted and a bacterial enumeration assay was performed. RESULTS: There was a significant difference (p < 0.05) in the number of bacteria recovered between the study groups at 48 h post-implantation. The mean recovery for test sutures was 559 cfu, and the mean recovery for control sutures was 16,831 cfu. Coated polyglactin 910 suture with triclosan provided a 30.5-fold (96.7%) reduction in the number of recovered bacteria compared to standard coated polyglactin 910 suture. CONCLUSIONS: This study demonstrates that coated polyglactin 910 suture with triclosan inhibits bacterial colonization of suture after direct in vivo challenge with S. aureus in a guinea pig model.

Animals↗

PubMed1976

Glomerulonephritis due to Staphylococcus aureus antigen.

Staphylococcus aureus antigen was identified within the glomeruli of a patient with acute bacterial endocarditis and diffuse glomerulonephritis. Routine immunofluorescence had revealed only granular deposits of complement (C3). C3 activator and C4 were not present. Direct immunofluorescence studies with a specific anti-Staphylococcus aureus conjugate were positive. Electron microscopy showed subepithelial and intramembranous electron-dense deposits. Eluates of the kidney did not contain anti-S. aureus antibody. The absence of immunoglobin suggests that the toxic action of S. aureus antigens may activate complement and cause glomerular injury and that immune complexes are not essential for the production of glomerulonephritis in this entity.

Adult↗

PubMed1976

Epidemiologic application of a typing method for Staphylococcus epidermidis strains by the serum-soft agar technic.

Using the serum-soft agar technic of Staphylococcus epidermidis typing, an epidemiologic study of pollution with S. epidermidis in the tuberculosis and pediatric wards of a hospital was conducted. Specimen samples were taken from 334 locations, including beds, bedspreads, pillows, doors and window knobs, chairs, tables, and incubators of premature infants. These were cultured on Staphylococcus 110 medium and the strains identified as S. epidermidis were obtained. Of the strains from both patients' rooms and the nurses' station in the tuberculosis ward a considerable number were of serotype 53, suggesting an interrelationship of this organism and these locations. In the rooms of newborns and premature infants in the pediatric ward, 55.5% of the strains of S. epidermidis isolated were of the serotype 53/408, indicating a high degree of pollution of these environments with these serotype strains.

Agar↗

PubMed1981

Temperature effect on cephalothin sensitivity of methicillin-resistant Staphylococcus aureus.

Nineteen methicillin-resistant Staphylococcus aureus isolates from clinical specimens were tested for cephalothin sensitivity by disk diffusion and tube-dilution methods using incubation temperatures of 35 C and 30 C. Resistant colonies were observed to grow within the zones of antibiotic inhibition for 17 of the 19 isolates at 30 C but not at 35 C incubation. Twenty control strains known to be methicillin-sensitive did not show these resistant colonies at 30 C. Five of the methicillin-resistant isolates were sensitive, one of intermediate sensitivity to cephalothin, and the rest were resistent by tube-dilution testing at 35 C. At 30 C, however, two isolates were of intermediate sensitivity, and the rest were resistant to cephalothin by tube-dilution testing. These observations strongly suggest that the 30 C incubation temperature is more reliable in detecting in-vitro resistance of methicillin-resistant strains of Staphylococcus aureus to cephalothin in agar as well as in liquid media.

Cephalothin↗

PubMed1982

Urinary tract infection due to coagulase-negative staphylococcus.

One hundred and fifty-six urine specimens with a pure culture of coagulase-negative Staphylococcus were studied. One hundred and eighteen charts were reviewed for clinical evidence of urinary tract infections. Twenty-four cases of urinary tract infection were found. The younger females in the study tended to have infection due to novobiocin resistant Staphylococcus in contrast to males and older females.

Adolescent↗

PubMed1993

Endocarditis due to Staphylococcus lugdunensis: report of 11 cases and review.

Staphylococcus lugdunensis is a recently described coagulase-negative staphylococcus that has been associated with human infections, including nine reported cases of infective endocarditis. The present study describes 11 other cases of infective endocarditis caused by this organism. The infection occurred in patients whose mean age was 61 years and was community-acquired in most cases. A preexisting cardiac abnormality was present in eight patients. Three of the 11 infections involved prosthetic valves. Ten strains were susceptible to penicillin. The destructive course of the infection, the need for valve replacement, and the high mortality suggest that S. lugdunensis causes a virulent form of endocarditis.

Adult↗

PubMed1984

Problems of venereal disease in Nigeria. 2. Staphylococcus aureus as a possible cause of non-gonococcal urethritis.

The incidence of non-gonococcal urethritis has increased more than four-fold in the last decade and is now one of the most common of the sexually transmitted diseases. In a study of 429 cases of male urethritis presenting to a health centre in Nigeria, 202 (41%) of the cases had Gram-positive cocci present. Culture grew Staphylococcus aureus in 178 (53.7%) of the cases. The sensitivity of the organisms to antibiotics was tested, enabling effective antibiotics to be identified. It is suggested that Staphylococcus aureus may be a major cause of non-gonococcal urethritis.

Adult↗

PubMed1975

New bacteriophages of Staphylococcus epidermidis.

Fifty-six phages designated the U-series and 34 phages designated the Ph-series were carefully examined. The spectrum of activity was established for 183 strains of Staphylococcus epidermidis from different countries and for 258 strains of Staphylococcus aureus. All 90 phages were active against strains of both species, but some differences in sensitivity were noted. Sixteen of the 90 phages were selected for phage typing of S. epidermidis. With use of a routine test dilution of phage (the highest dilution that yields confluent lysis of the propagation strain), 71.6% of 183 coagulase-negative staphylococci tested were sensitive to the phages; 42 phage patterns were observed. The results indicate that phage typing of S. epidermidis can be recommended for epidemiological and ecological purposes.

Humans↗

PubMed1978

Solid-phase radioimmunoassay for detection of staphylococcal antigen in serum of rabbits with endocraditis due to Staphylococcus aureus.

To aid in the rapid diagnosis of staphylococcal infection, a solid-phase radioimmunoassay for Staphylococcus aureus antigen was developed and evaluated in rabbits with staphylococcal endocarditis. Test specimens containing antigen were added to polystyrene tubes coated with antibody to S. aureus. Antigens immobilized on the tube were detected by adding radiolabeled antibody to S. aureus. Sensitivity for antigen was 0.312 microgram/ml in buffer and 1.25 microgram/ml in 50% rabbit serum. Cross-reactions were not observed with antigens extracted from streptococci; however, antigen extracted from Staphylococcus epidermidis (which contained ribitol-teichoic acid) could also be detected at low concentrations. Antigen was detected in each of 12 rabbits with S. aureus endocarditis but not in control rabbits. This assay is sensitive, specific, reproducible, and capable of detecting antigens in the serum of rabbits with endocarditis.

Animals↗

PubMed1985

Conjugative R plasmids in antimicrobial resistance of Staphylococcus aureus causing nosocomial infections.

Increasing resistance to aminoglycoside antimicrobial agents in clinical isolates of Staphylococcus aureus was encountered in one hospital over a three-year period. Eleven of 16 isolates, selected to represent different time periods, transferred gentamicin resistance on filter membranes with transfer properties and restriction-enzyme analyses that were similar to pAM899-1, a self-transferable gentamicin plasmid previously isolated from Staphylococcus epidermidis within the same hospital. Self-transferable gentamicin R plasmids were demonstrated in isolates from six other nosocomial environments as early as 1974 and, though showing different restriction-enzyme digests, were highly related to pAM899-1 on the basis of Southern hybridization. These recently recognized, self-transferable plasmids seem to share a common evolutionary background and are important contributors to the increased resistance encountered in nosocomial staphylococci.

Conjugation, Genetic↗

PubMed1990

Characterization of a neutrophil-inhibitory factor from clinically significant Staphylococcus epidermidis.

Sixteen isolates of Staphylococcus epidermidis recovered from blood cultures of patients were examined for ability to adhere to plastic tubes, for agglutinability with concanavalin A, and for the ability to inhibit the bactericidal activity of neutrophils collected from healthy human volunteers. Neutrophil inhibition was induced by six of nine isolates associated with clinically significant infections but by only one of seven clinically defined as blood contaminants (P = .05). Six of the eight significant bacteremic episodes were associated with neutrophil-inhibitory isolates (P = .03). Neutrophil inhibition was independent of either adherence or ConA agglutination. Neutrophil inhibition may represent an independent virulence factor associated with Staphylococcus epidermidis.

Agglutination Tests↗

PubMed1991

Correlation of in-vitro parameters of antimicrobial activity with prophylactic efficacy in an intradermal model of Staphylococcus aureus infection.

Cephalosporins differ in their ability to prevent staphylococcal wound infection. Although the reasons for the observed differences are not fully understood, the susceptibility of cephalosporins to hydrolysis by staphylococcal beta-lactamase has been correlated with failures of prophylaxis. To investigate the effect of beta-lactamase stability and other in-vitro parameters of the bacterial-antimicrobial interaction on the efficacy of antimicrobial prophylaxis, two beta-lactamase-stable agents, cefuroxime and cefmetazole were compared to cefazolin and cefamandole in an in-vivo model of intradermal infection employing four strains of Staphylococcus aureus. Following intraperitoneal administration of a single dose of cephalosporin or placebo, guinea pigs were inoculated at multiple intradermal sites with 2 x 10(7) cfu of a strain of staphylococcus. For three strains, the area of induration at 24 h following inoculation was significantly smaller in guinea pigs receiving prophylaxis with cephalosporins versus placebo; no cephalosporin was effective against the fourth strain. Differences were also noted among the cephalosporins; prophylaxis with cefuroxime and cefmetazole resulted in smaller lesions than seen in animals given cefazolin or cefamandole. Poor correlation was noted between results of the in-vivo model and in-vitro determinants of the bacterial-antimicrobial interaction which were MIC values, time-kill curves, and the rates of beta-lactamase-mediated cephalosporin hydrolysis by the different strains. The model demonstrated unexplained failures of prophylaxis and unexpected differences in efficacy of various cephalosporins as has been described before. This study highlights the need for an improved animal model of surgical antimicrobial prophylaxis and the identification of in-vitro determinants that predict in-vivo prophylactic efficacy more accurately.

Animals↗

PubMed1994

In-vitro synergy between aminoglycosides deployed against Staphylococcus spp. harbouring a 6'-aminoglycoside acetyltransferase, 2"-aminoglycoside phosphotransferase enzyme.

In-vitro synergistic effects between commercial aminoglycosides are described for gentamicin resistant Staphylococcus strains harbouring 6'-aminoglycoside acetyltransferase activity. Seventy eight strains were studied using the double-disc test and synergy was observed with combinations in which at least one of the components has a garosamine-like 6'-aminosugar. These results were confirmed in chequerboard titrations (sigma FIC < or = 0.5) carried out on Staphylococcus epidermidis strains RYC13036 and RYC4904. Additionally, a clear reduction in tobramycin acetylating activity was observed in the presence of gentamicin or netilmicin in crude extracts of these strains. These experiments suggest that the observed synergy is due to inhibition of the aminoglycoside-modifying enzyme by aminoglycosides with a garosamine like 6'-aminosugar component.

Acetyltransferases↗

PubMed2002

Emergence of vancomycin-intermediate Staphylococcus aureus in a Belgian hospital: microbiological and clinical features.

In 1999, all clinical Staphylococcus aureus isolates from patients admitted to a Belgian University hospital were tested for decreased vancomycin susceptibility. Three vancomycin-intermediate Staphylococcus aureus (VISA) and four hetero-VISA strains were detected among 2145 isolates tested. They emerged from strains that belonged to locally endemic methicillin-resistant S. aureus (MRSA) genotypes in three patients who had received repeated courses of vancomycin therapy. A cystic fibrosis patient with MRSA/VISA-associated broncho-pulmonary exacerbation was successfully treated by continuous vancomycin infusion plus fusidic acid followed by oral minocycline-fusidic acid. Two other patients had VISA recovered from specimens of undetermined clinical significance. Emergence of VISA variants of endemic MRSA strains in Belgium warrants active microbiological surveillance and careful monitoring of vancomycin therapy. Therapy with high-dose vancomycin administered by continuous infusion in combination with other antimicrobials may be a therapeutic option worth investigating for VISA infection.

Adolescent↗

PubMed2004

Nucleotide sequence and organization of the multiresistance plasmid pSCFS1 from Staphylococcus sciuri.

OBJECTIVES: The multiresistance plasmid pSCFS1 from Staphylococcus sciuri was sequenced completely and analysed with regard to its gene organization and the putative role of a novel ABC transporter in antimicrobial resistance. METHODS: Plasmid pSCFS1 was transformed into Staphylococcus aureus RN4220, overlapping restriction fragments were cloned into Escherichia coli plasmid vectors and sequenced. For further analysis of the ABC transporter, a approximately 3 kb EcoRV-HpaI fragment was cloned into the staphylococcal plasmid pT181MCS and the respective S. aureus RN4220 transformants were subjected to MIC determination. RESULTS: A total of 14 ORFs coding for proteins of >100 amino acids were detected within the 17 108 bp sequence of pSCFS1. Five of them showed similarity to recombination/mobilization genes while another two were similar to plasmid replication genes. In addition to the previously described genes cfr for chloramphenicol/florfenicol resistance and erm(33) for inducible resistance to macrolide-lincosamide-streptogramin B resistance, a Tn554-like spectinomycin resistance gene and Tn554-related transposase genes were identified. Moreover, a novel ABC transporter was detected and shown to mediate low-level lincosamide resistance. CONCLUSION: Plasmid pSCFS1 is composed of various parts which show similarity to sequences known to occur on plasmids or transposons of Gram-positive, but also Gram-negative bacteria. It is likely that pSCFS1 represents the result of inter-plasmid recombination events also involving the truncation of a Tn554-like transposon.

ATP-Binding Cassette Transporters↗

PubMed2005

In vitro resistance to the CSalphabeta-type antimicrobial peptide ASABF-alpha is conferred by overexpression of sigma factor sigB in Staphylococcus aureus.

OBJECTIVES: ASABF (Ascaris suum antibacterial factor) is a CSalphabeta-type antimicrobial peptide isolated from nematodes. ASABF-alpha, a member of ASABF, is particularly effective against the gram-positive pathogen Staphylococcus aureus. In this study, we investigated the role of sigB expression on ASABF-resistance in S. aureus. METHODS: Based on preliminary characterization of the ASABF-resistant strain, Mu50, we speculated that the alternative sigma factor sigB may regulate resistance against antimicrobial peptides. To test this hypothesis, the ASABF susceptibility was compared between NKSB (a sigB-knockout derivative of N315) and its sigB-overexpressing derivative. In addition, similar experiments were carried out for N315ex, a deletion mutant of N315 for SCCmec (Staphylococcus cassette chromosome mec) which contains essential genes for beta-lactam resistance. RESULTS: The sigB-overexpressing NKSB acquired an increased resistance to ASABF-alpha compared with the parent strain. The sigB-induced ASABF-alpha resistance was also observed in N315ex. CONCLUSIONS: The overexpression of sigB confers resistance to the antimicrobial peptide, ASABF-alpha. SCCmec is not essential for this resistance.

Animals↗