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PubMedDate not supplied

Molecular epidemiology of methicillin-resistant Staphylococcus aureus.

Subtyping methicillin- resistant Staphylococcus aureus (MRSA) isolates and tracking nosocomial infections have evolved from phenotypic to genotypic approaches; most laboratories now depend on pulsed-field gel electrophoresis (PFGE). We discuss the limitations of current image-based genotyping methods, including PFGE, and the advantages (including ease of entering data into a database) of using DNA sequence analysis to control MRSA infections in health-care facilities.

Bacterial Typing Techniques↗

PubMed1998

Identification and characterization of the PutP proline permease that contributes to in vivo survival of Staphylococcus aureus in animal models.

Staphylococcus aureus is an important pathogen of humans and other animals, causing bacteremia, abscesses, endocarditis, and other infectious syndromes. A signature-tagged mutagenesis (STM) system was adapted for use in studying the genes required for in vivo survival of S. aureus. An STM library was ultimately created in S. aureus RN6390, with Tn917 being used to create the transposon mutations. Pools of S. aureus RN6390 mutants were screened in mouse abscess, bacteremia, and wound infection models for growth attenuation after in vivo passage. One of the mutants that was identified displayed marked attenuation following large-pool screening in all three animal models, which was confirmed in bacteremia and endocarditis models of infection with a smaller pool of mutants. Sequence analysis of the entire open reading frame showed a 99% identity to the high-affinity proline permease (putP) gene characterized in another strain of S. aureus. In wound and murine abscess infection models, the putP mutant was approximately 10-fold more attenuated than was wild-type strain RN6390. Another S. aureus strain transduced with the putP mutation also displayed an attenuated phenotype after passage in the wound model. A [3H]proline uptake assay showed that less proline was specifically transported into the putP mutant than into strain RN6390. The reduced viability of the bacteria possessing the mutation in the S. aureus high-affinity proline permease suggests that proline scavenging by the bacteria is important for in vivo growth and proliferation and that analogs of proline may serve as potential antistaphylococcal therapeutic agents.

Amino Acid Transport Systems, Neutral↗

PubMed1992

[A study of nasal carriage of methicillin-resistant Staphylococcus aureus].

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important microorganisms in nosocomial infection. The Hospital staff working in MRSA endemic wards are known to have MRSA in their nasal cavity. The nasal carriage of MRSA was detected in staff members and patients of two hospitals. In Niigata University Hospital, 10 out of 109 nurses and 8 out of 142 doctors were found to be MRSA carriers. On the other hand, in Nagaoka Red Cross Hospital, 25 out of 448 nurses were found to be MRSA carriers, however, no carrier was found in 23 doctors. These strains were also resistant to MCIPC, IPM, TFLX and OFLX, whereas they remained sensitive to VCM. The coagulase types of MRSA isolated from the hospital staff and patients were II, IV and VII, although those of Methicillin-sensitive S. aureus (MSSA) consisted of all types. Elimination of nasal MRSA from the carriers was considered for avoiding hospital outbreaks caused by this potential pathogen. Forty hospital staff and 19 patients, in who's MRSA was found persisting in their nasal cavity, were treated by povidone iodine and chloramphenicol (CP) MRSA disappeared in 44% and 84% of the nasal carriers by povidone iodine and CP, respectively.

Anti-Bacterial Agents↗

PubMed1996

Epidemiology of Staphylococcus aureus during space flight.

Staphylococcus aureus was isolated over 2 years from Space Shuttle mission crewmembers to determine dissemination and retention of bacteria. Samples before and after each mission were from nasal, throat, urine, and feces and from air and surface sampling of the Space Shuttle. DNA fingerprinting of samples by digestion of DNA with SmaI restriction endonuclease followed by pulsed-field gel electrophoresis showed S. aureus from each crewmember had a unique fingerprint and usually only one strain was carried by an individual. There was only one instance of transfer between crewmembers. Strains from interior surfaces after flight matched those of crewmembers, suggesting microbial fingerprinting may have forensic application.

DNA Fingerprinting↗

PubMed2004

Human-to-dog transmission of methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) was cultured from the nose of a healthy dog whose owner was colonized with MRSA while she worked in a Dutch nursing home. Pulsed-field gel electrophoresis and typing of the staphylococcal chromosome cassette mec (SCCmec) region showed that both MRSA strains were identical.

Adult↗

PubMed2005

A LysR-type regulator, CidR, is required for induction of the Staphylococcus aureus cidABC operon.

The Staphylococcus aureus cidABC and lrgAB operons have been shown to regulate murein hydrolase activity and affect antibiotic tolerance. The cid operon enhances murein hydrolase activity and antibiotic sensitivity, whereas the lrg operon inhibits these processes. Based on these findings and the structural similarities of the cidA and lrgA gene products to the bacteriophage holin family of proteins, we have proposed that the cid and lrg operons encode holin- and antiholin-like proteins, respectively, that function to control the murein hydrolase activity produced by the bacteria. Analysis of cid operon transcription revealed the presence of two transcripts, one spanning all three cid genes and whose expression is induced by growth in the presence of acetic acid and the other spanning cidB and cidC only that is produced in a sigma B-dependent manner. The cidABC operon lies immediately downstream from the cidR gene, encoding a potential LysR-type transcriptional regulator. In this study, we demonstrate that cidR is involved in the regulation of cidABC expression. Northern blot analyses revealed that the cidR gene product positively regulates cidABC expression by increasing transcription in the presence of acetic acid produced as a result of the metabolism of glucose. As expected for an operon that encodes a positive effector of murein hydrolase activity, the upregulation of cidABC expression resulted in increased murein hydrolase activity produced by these cells. Furthermore, it was demonstrated that antibiotic tolerance and stationary-phase survival of S. aureus are affected by the cidR gene. Taken together, these results demonstrate that the cidR gene product functions as a transcriptional activator of cidABC transcription in response to acetic acid accumulation in the growth medium.

Base Sequence↗

PubMed2005

Receptors for endogenous and heterogenous hydroxamate siderophores in Staphylococcus aureus B 471.

In Staphylococcus aureus B47 grown in iron-restricted medium, six new, iron-regulated proteins occurred in cytoplasmic membrane. Protein of 14kDa has bound two complexes of iron: Fe(III)-staphylobactin and Fe(III)-acinetoferrin. Complexes of Fe(llI)-ferrichrome and Fe(III)-rhodotorulic acid were not bound to any of new membrane protein. Iron of Fe(III)-staphylobactin and Fe(IIl)-acinetoferrin complexes was transported into the cells.

Cell Membrane↗

PubMed1989

[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.

Culture Media↗

PubMed1978

In vitro activity of rifampin alone and in combination with nafcillin and Vancomycin against pathogenic strains of Staphylococcus aureus.

Twenty strains of Staphylococcus aureus isolated from patients with endocarditis were examined in vitro for susceptibility to rifampin, nafcillin, and vancomycin and to combinations of rifampin with nafcillin or vancomycin. Minimum bactericidal concentrations of rifampin ranged from 0.0031 to 0.0125 mug/ml, of nafcillin ranged from 0.078 to 0.312 mug/ml, and of vancomycin ranged from 0.312 to 1.25 mug/ml. The combination of rifampin with nafcillin was synergistic for 12 strains; the combination of rifampin plus vancomycin was synergistic for 5 of the isolates.

Drug Synergism↗

PubMed2002

The prevalence and mechanisms of vancomycin resistance in Staphylococcus aureus.

The emergence of Staphylococcus aureus resistant to vancomycin has caused considerable concern. Such strains are currently rare, although they have been isolated from many areas of the world. Considerable controversy surrounds strains of S. aureus displaying heterogeneous resistance to vancomycin regarding their definition and methods for detection. This has led to considerable variance in estimates of prevalence (0-1.3%-20% in Japan) and has hindered efforts to define the clinical relevance of these strains. The mechanism of resistance involves a complex reorganization of cell wall metabolism, leading to a grossly thickened cell wall with reduced peptidoglycan cross-linking. There may be many different ways in which strains achieve this endpoint. Current knowledge and theories are summarized.

Anti-Bacterial Agents↗

PubMed1988

Pulmonary infection due to methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) are now causing severe clinical infection on a worldwide basis. Pulmonary infection due to MRSA although widely reported is poorly documented. We report the predisposing factors, underlying diseases, treatment and outcome in 4 patients with pneumonia, 3 patients with empyema thoracis, 1 patient with pneumonia and empyema thoracis, 1 patient with pneumonia plus lobectomy wound infection and 2 patients with lung abscess. Vancomycin was highly effective in treatment, a finding compatible with experience treating other severe MRSA infections.

Adolescent↗

PubMed1997

Methicillin resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) has had a major impact on health care causing much anxiety and distress to patients and staff, and resulting in huge financial costs. It has been widely publicised by the media which in some cases has added to people's alarm. The screening, treatment and resultant isolation affects all aspects of the patient's care and will also influence the management of any wounds. MRSA has been isolated in both acute and chronic wounds and so the management of these must be included in any infection control policy.

Acute Disease↗

PubMed1997

Molecular mechanisms of methicillin resistance in Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) strains are among the most common nosocomial pathogens. The most significant mechanism of resistance to methicillin in this-species is the acquisition of a genetic determinant (mecA gene). However, resistance seems to have a more complex molecular basis, since additional chromosomal material is involved in such resistance. Besides, overproduction of penicillinase and/or alterations in the PBPs can contribute to the formation of resistance phenotypes. Genetic and environmental factors leading to MRSA are reviewed.

Bacterial Proteins↗

PubMed1982

Binding of 3-O-acetyl-4"-O-isovaleryltylosin to ribosomes from a macrolide-resistant strain of Staphylococcus aureus.

The resistance of Staphylococcus aureus MS-9610 to tylosin and 3-O-acetyltylosin was due to the decreased affinity of its ribosome system to these macrolides. However, 3-O-acetyl-4"-O-isovaleryltylosin was found to bind to ribosomes of the strain about three times more than 3-O-acetyltylosin. This binding was not interfered by tylosin and 3-O-acetyltylosin. The 4"-O-acyl group and the mycinose moiety were suggested to have an important role in the binding of tylosin derivatives to ribosomes of resistant strains.

Anti-Bacterial Agents↗

PubMed1986

Sequence of the exfoliative toxin B gene of Staphylococcus aureus.

We sequenced the Staphylococcus aureus exfoliative toxin B gene contained on a 1.7-kilobase HindIII fragment of plasmid pRW001. The gene was located by comparison of the amino acid sequences of open reading frames with the amino-terminal sequence of exfoliative toxin B and the total amino acid composition of the protein (A.D. Johnson, L. Spero, J.S. Cades, and B.T. De Cicco, Infect. Immun. 24:679-684, 1979). The primary translation product consists of 274 amino acids and contains a 31-amino-acid N-terminal peptide presumably necessary for transport.

Amino Acid Sequence↗

PubMed1993

[Hvidovre Hospital. Measures to control the spread of imported multiresistant Staphylococcus aureus].

Methicillin-resistant Staphylococcus aureus (MRSA) are endemic in many hospitals abroad. Patients transferred from these hospitals may give rise to a spread of MRSA in Scandinavian hospitals, where MRSA only occur sporadically. A spread of MRSA may have great therapeutic and economic consequences for the local health care system and should therefore be met by strict hygienic measures. In Hvidovre Hospital patients transferred from or recently admitted to hospitals outside Scandinavia, are screened for MRSA. Patients carrying MRSA are isolated and discharged as soon as possible. Attempts are made to eliminate the carrier state by means of chlorhexidine.

Adult↗

PubMed2002

Methicillin resistance in Staphylococcus aureus: mechanisms and modulation.

Staphylococcus aureus is a major pathogen both within hospitals and in the community. Methicillin, a beta-lactam antibiotic, acts by inhibiting penicillin-binding proteins (PBPs) that are involved in the synthesis of peptidoglycan, an essential mesh-like polymer that surrounds the cell. S. aureus can become resistant to methicillin and other beta-lactam antibiotics through the expression of a foreign PBP, PBP2a, that is resistant to the action of methicillin but which can perform the functions of the host PBPs. Methicillin-resistant S. aureus isolates are often resistant to other classes of antibiotics (through different mechanisms) making treatment options limited, and this has led to the search for new compounds active against these strains. An understanding of the mechanism of methicillin resistance has led to the discovery of accessory factors that influence the level and nature of methicillin resistance. Accessory factors, such as Fem factors, provide possible new targets, while compounds that modulate methicillin resistance such as epicatechin gallate, derived from green tea, and corilagin, provide possible lead compounds for development of inhibitors.

Bacterial Proteins↗

PubMed1977

[Glycine dependence of Staphylococcus aureus strains].

Glycine dependent Staphylococcus aureus var. bovis strains (TSCHAPE and RISCHE 1971) were tested for their ability to grow on glycine containing and glycine deprived media. We observed glycine dependence only in minimal media. In complete media the strains grew in absence of glycine. Testing the ability of some glycine precursors we found that in minimal media glycine could be replaced by threonine and in some cases by serine. One mutant (Gly 100 Glyox.r.) was able to metabolize glyoxylate instead of glycine. Aspartic acid was metabolized in presence of glycine. Using 14C-aspartic acid we detected 14C-glycine and 14C-threonine. Presumably the bacteria metabolize aspartic acid to glycine via threonine.

Aspartic Acid↗